RNA modifications and their role in gene expression regulation and cellular
function
Introduction
Beyond its central roles encoding genetic information and serving as an intermediary between
DNA and protein synthesis, RNA itself represents a sophisticated regulatory network
controlling gene expression through extensive post-transcriptional modifications impacting
stability, localization and translation. Over 160 distinct chemical modifications fine-tune
ribosomal, transfer, messenger and non-coding RNA functionality across all domains of life.
These modifications, occurring through enzymes recognizing specific sequence/structural
motifs, influence molecular interactions determining developmental processes, signal
transduction, stress responses and disease states in ways recently coming into focus.
Nuanced roles of RNA modifications emerged through innovative strategies enabling high-
throughput mapping, as technologies advanced from two-dimensional gel electrophoresis
through mass spectrometry and deep sequencing. New methods delineate modification-
guided regulons determining molecular phenotypes. Key recent insights reveal how
combinatorial RNA modifications influence alternative splicing, RNA stability, targeting
pathways governing biological complexity, health and disease at the interface between
epigenetics and genomics. Their deregulation associates with developmental defects and
cancer etiology.
This review surveys major classes and regulators of RNA modifications across coding and
non-coding transcripts, their expanding functional landscape contributing to post-
transcriptional gene regulation, as well as exciting frontiers promising to clarify diverse
physiological roles and disease implications while inspiring novel therapeutic intervention
strategies. A deeper mechanistic understanding promises impacting scientific domains from
developmental biology to Precision Medicine through decoding long-overlooked layers of
complex regulatory programs.
RNA Modification Classes and their Distribution
Detected through mass spectrometry, bioinformatics and emergent high-throughput mapping,
major RNA modification classes regulate molecular behaviors:
Methylation
- N6-methyladenosine (m6A), most abundant mammalian modification guiding mRNA fate.
- 2’-O-methylations stabilizing rRNAs, stabilizing cap structures.
Pseudouridylations
- Ψ modifications distributed across rRNAs, tRNAs, snoRNAs stabilizing secondary
structures.
Other Base Modifications
- Inosine (I), queuosine (Q), 5-methylcytidine regulating tRNAs, rRNAs.
Isopentenyladenosine (i6A)
- Modification guiding tRNA stability, structure in all domains of life.
Acetylation
- N6-acetyladenosine emerging as dynamic mRNA modification signal.
Besides endogenous modifications, external modifications introduced by toxins or UV
damage regulate stress responses. Overall, combinatorial RNA ‘epitranscriptomics’ through
widespread base and ribose modifications pervasively influence molecular functions.
RNA Modification Enzymes and their Mechanisms
Diverse enzyme classes install RNA modifications through sequence/structure-specific
recognition:
Methyltransferases
- S-adenosylmethionine-dependent enzymes mediate m6A, Ψ methylations and others.
Pseudouridine Synthases
- TRU/TruB family enzymes isomerize uridines to pseudouridines in tRNAs, rRNAs.
RNA Editases
- ADAR family deaminases mediating A-to-I editing in coding/non-coding RNAs.
Methylcytosine Dimethyltransferases
- Regulate m5C modifications guiding rRNA maturation, tRNA stability.
Ribose Methyltransferases
- Install 2’-O-methylations displaying broad phyletic conservation.
Acetyltransferases
- Writers mediate dynamic, regulated N6-acetyladenosine signaling.
Overall, diverse classes of RNA modification enzymes precisely tailor molecular functions
through recognition of sequence/structure contexts, advancing post-transcriptional regulatory
complexity across all domains. Their study promises novel insight across biology.
Roles of RNA Modifications in Gene Regulation
Combinatorial RNA modifications govern molecular processes through distinct mechanisms:
Alternative Splicing Regulation
- m6A recruits splicing factors guiding cotranscriptional intron removal decisions.
RNA Localization and Targeting
- m6A, Ψ guide transcripts to subcellular destinations like stress granules.
RNA Translation
- m6A near start/stop codons enhances translation. Pseudouridines stabilize tRNA structures.
RNA Stability
- 2’-O-methylations protect mRNA 5’/3’ ends from cleavage. Pseudouridines stabilize
tRNAs, rRNAs.
RNA Structuring
- Pseudouridines, isopentenyladenosine rigidify tRNA conformations guiding
aminoacylation.
Non-coding RNA Function
- m6A regulates lncRNA stability/processing. Pseudouridines stabilize sno/snRNAs guides.
Oxidative Stress Response
- N6-acetyladenosine dynamically regulates heat shock response transcripts.
Through combinatorial crosstalk between writer/reader/eraser proteins mediating installations
and interpretations, modifications add layers integrating RNA functionality with
environmental sensing and physiological signaling at whole-cell and organismal levels. The
discovery potential through epitranscriptomics remains exponential.
Roles in Development and Disease
RNA modification deregulation associates with developmental defects and disease through
impacts on molecular pathways:
- NSun2-mediated m5C deficiency impairs ribosome maturation and causes growth defects.
- FTO demethylase links obesity to dynamic m6A-dependent adipogenesis.
- ADAR1 deficiency causes A-to-I editing defects lethal to mice through innate immunity
failings.
- Virus hijacking/ inhibition of host m6A writers aids evasion of antiviral defenses.
- FTO, ALKBH5 dysregulation links m6A erasure defects to cancers through sustained
oncogene translation.
- TRNA modifications maintain proteostasis; defects influence neurological disorders and
METTL3 links m6A-dependent transcript stability to metastasis.
Overall, numerous genetic disorders emerge from unbalanced RNA modification
homeostasis. Deregulated epitranscriptome profiles arise across disease states, promising
novel diagnostic/prognostic biomarkers or therapeutic intervention strategies if regulatory
roles are clarified. Combinatorial “epitranscriptomic therapies” targeting RNA modifications
represent an emerging Precision Medicine frontier if impacts are deciphered.
High-Throughput Modification Mapping
Technological advances now globally map and quantify RNA modifications at single-
nucleotide resolution through:
- m6A-Seq and its variants couple anti-m6A antibody IP with deep sequencing.
- Pseudo-Seq couples anti-Ψ antibody with sequencing.
- MeRIP-Seq couples anti-methylated ribose IP with sequencing.
- RAM (RNA annotation and mapping) couples mass spectrometry with sequencing.
- CLIP-based methods map protein-RNA interactions.
- Ribosome profiling delineates modified transcript subsets.
- Multiomics integration clarifies regulatory interplay across molecules.
Overall, innovations delineate comprehensive landscape of RNA modifications influencing
transcriptome-wide gene expression, alternative splicing, localization and translation on a
system-wide scale in health and disease. The next wave involves functional validation
through epigenetic perturbations.
Frontiers and Future Directions
As technological and computational capabilities exponentially advance resolution into
regulatory RNA epitranscriptomes, frontiers emerge across diverse fields impacting Precision
Medicine and synthetic biology:
- Delineating tissue- and condition-specific epitranscriptomic maps guides biomarker,
therapeutic target discovery.
- Determining ‘writers’, ‘erasers’, ‘readers’ mediating RNA-protein interaction networks
governing development.
- Elucidating mechanisms precisely linking epitranscriptomic alterations to disease
pathogenesis and progression.
- Designing small molecule or CRISPR-based epitranscriptomic modulators precisely
targeting modifier enzymes.
- Applying targeted RNA modification patterning or temporal control of their dynamic
regulation.
- Synthesizing minimal genomes with non-natural modification incorporation capabilities.
- Combining modifications, alternative polyadenylation, editing in synthetic genetic circuits
with emergent behaviors.
- Characterizing intergenerational epitranscriptomic inheritance and non-Mendelian
transgenerational effects.
Progress depends upon accessible public databases, open science practices transparently
sharing resources unlocking complex regulatory mechanisms central to molecular, cellular
and system-wide understanding. Overall, epitranscriptomics represents a burgeoning ‘third
layer’ of regulatory complexity connecting gene expression control to environmental sensing,
development and programmed cellular states through nuanced combinatorial RNA post-
transcriptional programs.
Beyond its central roles encoding genetic information and serving as an intermediary between
DNA and protein synthesis, RNA itself represents a sophisticated regulatory network
controlling gene expression through extensive post-transcriptional modifications impacting
stability, localization and translation. Over 160 distinct chemical modifications fine-tune
ribosomal, transfer, messenger and non-coding RNA functionality across all domains of life.
These modifications, occurring through enzymes recognizing specific sequence/structural
motifs, influence molecular interactions determining developmental processes, signal
transduction, stress responses and disease states in ways recently coming into focus.
Nuanced roles of RNA modifications emerged through innovative strategies enabling high-
throughput mapping, as technologies advanced from two-dimensional gel electrophoresis
through mass spectrometry and deep sequencing. New methods delineate modification-
guided regulons determining molecular phenotypes. Key recent insights reveal how
combinatorial RNA modifications influence alternative splicing, RNA stability, targeting
pathways governing biological complexity, health and disease at the interface between
epigenetics and genomics. Their deregulation associates with developmental defects and
cancer etiology.
This review surveys major classes and regulators of RNA modifications across coding and
non-coding transcripts, their expanding functional landscape contributing to post-
transcriptional gene regulation, as well as exciting frontiers promising to clarify diverse
physiological roles and disease implications while inspiring novel therapeutic intervention
strategies. A deeper mechanistic understanding promises impacting scientific domains from
developmental biology to Precision Medicine through decoding long-overlooked layers of
complex regulatory programs.
RNA Modification Classes and their Distribution
Detected through mass spectrometry, bioinformatics and emergent high-throughput mapping,
major RNA modification classes regulate molecular behaviors:
Methylation
- N6-methyladenosine (m6A), most abundant mammalian modification guiding mRNA fate.
- 2’-O-methylations stabilizing rRNAs, stabilizing cap structures.
Pseudouridylations
- Ψ modifications distributed across rRNAs, tRNAs, snoRNAs stabilizing secondary
structures.
Other Base Modifications
- Inosine (I), queuosine (Q), 5-methylcytidine regulating tRNAs, rRNAs.
Isopentenyladenosine (i6A)
- Modification guiding tRNA stability, structure in all domains of life.
Acetylation
- N6-acetyladenosine emerging as dynamic mRNA modification signal.
Besides endogenous modifications, external modifications introduced by toxins or UV
damage regulate stress responses. Overall, combinatorial RNA ‘epitranscriptomics’ through
widespread base and ribose modifications pervasively influence molecular functions.
RNA Modification Enzymes and their Mechanisms
Diverse enzyme classes install RNA modifications through sequence/structure-specific
recognition:
Methyltransferases
- S-adenosylmethionine-dependent enzymes mediate m6A, Ψ methylations and others.
Pseudouridine Synthases
- TRU/TruB family enzymes isomerize uridines to pseudouridines in tRNAs, rRNAs.
RNA Editases
- ADAR family deaminases mediating A-to-I editing in coding/non-coding RNAs.
Methylcytosine Dimethyltransferases
- Regulate m5C modifications guiding rRNA maturation, tRNA stability.
Ribose Methyltransferases
- Install 2’-O-methylations displaying broad phyletic conservation.
Acetyltransferases
- Writers mediate dynamic, regulated N6-acetyladenosine signaling.
Overall, diverse classes of RNA modification enzymes precisely tailor molecular functions
through recognition of sequence/structure contexts, advancing post-transcriptional regulatory
complexity across all domains. Their study promises novel insight across biology.
Roles of RNA Modifications in Gene Regulation
Combinatorial RNA modifications govern molecular processes through distinct mechanisms:
Alternative Splicing Regulation
- m6A recruits splicing factors guiding cotranscriptional intron removal decisions.
RNA Localization and Targeting
- m6A, Ψ guide transcripts to subcellular destinations like stress granules.
RNA Translation
- m6A near start/stop codons enhances translation. Pseudouridines stabilize tRNA structures.
RNA Stability
- 2’-O-methylations protect mRNA 5’/3’ ends from cleavage. Pseudouridines stabilize
tRNAs, rRNAs.
RNA Structuring
- Pseudouridines, isopentenyladenosine rigidify tRNA conformations guiding
aminoacylation.
Non-coding RNA Function
- m6A regulates lncRNA stability/processing. Pseudouridines stabilize sno/snRNAs guides.
Oxidative Stress Response
- N6-acetyladenosine dynamically regulates heat shock response transcripts.
Through combinatorial crosstalk between writer/reader/eraser proteins mediating installations
and interpretations, modifications add layers integrating RNA functionality with
environmental sensing and physiological signaling at whole-cell and organismal levels. The
discovery potential through epitranscriptomics remains exponential.
Roles in Development and Disease
RNA modification deregulation associates with developmental defects and disease through
impacts on molecular pathways:
- NSun2-mediated m5C deficiency impairs ribosome maturation and causes growth defects.
- FTO demethylase links obesity to dynamic m6A-dependent adipogenesis.
- ADAR1 deficiency causes A-to-I editing defects lethal to mice through innate immunity
failings.
- Virus hijacking/ inhibition of host m6A writers aids evasion of antiviral defenses.
- FTO, ALKBH5 dysregulation links m6A erasure defects to cancers through sustained
oncogene translation.
- TRNA modifications maintain proteostasis; defects influence neurological disorders and
METTL3 links m6A-dependent transcript stability to metastasis.
Overall, numerous genetic disorders emerge from unbalanced RNA modification
homeostasis. Deregulated epitranscriptome profiles arise across disease states, promising
novel diagnostic/prognostic biomarkers or therapeutic intervention strategies if regulatory
roles are clarified. Combinatorial “epitranscriptomic therapies” targeting RNA modifications
represent an emerging Precision Medicine frontier if impacts are deciphered.
High-Throughput Modification Mapping
Technological advances now globally map and quantify RNA modifications at single-
nucleotide resolution through:
- m6A-Seq and its variants couple anti-m6A antibody IP with deep sequencing.
- Pseudo-Seq couples anti-Ψ antibody with sequencing.
- MeRIP-Seq couples anti-methylated ribose IP with sequencing.
- RAM (RNA annotation and mapping) couples mass spectrometry with sequencing.
- CLIP-based methods map protein-RNA interactions.
- Ribosome profiling delineates modified transcript subsets.
- Multiomics integration clarifies regulatory interplay across molecules.
Overall, innovations delineate comprehensive landscape of RNA modifications influencing
transcriptome-wide gene expression, alternative splicing, localization and translation on a
system-wide scale in health and disease. The next wave involves functional validation
through epigenetic perturbations.
Frontiers and Future Directions
As technological and computational capabilities exponentially advance resolution into
regulatory RNA epitranscriptomes, frontiers emerge across diverse fields impacting Precision
Medicine and synthetic biology:
- Delineating tissue- and condition-specific epitranscriptomic maps guides biomarker,
therapeutic target discovery.
- Determining ‘writers’, ‘erasers’, ‘readers’ mediating RNA-protein interaction networks
governing development.
- Elucidating mechanisms precisely linking epitranscriptomic alterations to disease
pathogenesis and progression.
- Designing small molecule or CRISPR-based epitranscriptomic modulators precisely
targeting modifier enzymes.
- Applying targeted RNA modification patterning or temporal control of their dynamic
regulation.
- Synthesizing minimal genomes with non-natural modification incorporation capabilities.
- Combining modifications, alternative polyadenylation, editing in synthetic genetic circuits
with emergent behaviors.
- Characterizing intergenerational epitranscriptomic inheritance and non-Mendelian
transgenerational effects.
Progress depends upon accessible public databases, open science practices transparently
sharing resources unlocking complex regulatory mechanisms central to molecular, cellular
and system-wide understanding. Overall, epitranscriptomics represents a burgeoning ‘third
layer’ of regulatory complexity connecting gene expression control to environmental sensing,
development and programmed cellular states through nuanced combinatorial RNA post-
transcriptional programs.
Beyond its central roles encoding genetic information and serving as an intermediary between
DNA and protein synthesis, RNA itself represents a sophisticated regulatory network
controlling gene expression through extensive post-transcriptional modifications impacting
stability, localization and translation. Over 160 distinct chemical modifications fine-tune
ribosomal, transfer, messenger and non-coding RNA functionality across all domains of life.
These modifications, occurring through enzymes recognizing specific sequence/structural
motifs, influence molecular interactions determining developmental processes, signal
transduction, stress responses and disease states in ways recently coming into focus.
Nuanced roles of RNA modifications emerged through innovative strategies enabling high-
throughput mapping, as technologies advanced from two-dimensional gel electrophoresis
through mass spectrometry and deep sequencing. New methods delineate modification-
guided regulons determining molecular phenotypes. Key recent insights reveal how
combinatorial RNA modifications influence alternative splicing, RNA stability, targeting
pathways governing biological complexity, health and disease at the interface between
epigenetics and genomics. Their deregulation associates with developmental defects and
cancer etiology.
This review surveys major classes and regulators of RNA modifications across coding and
non-coding transcripts, their expanding functional landscape contributing to post-
transcriptional gene regulation, as well as exciting frontiers promising to clarify diverse
physiological roles and disease implications while inspiring novel therapeutic intervention
strategies. A deeper mechanistic understanding promises impacting scientific domains from
developmental biology to Precision Medicine through decoding long-overlooked layers of
complex regulatory programs.
RNA Modification Classes and their Distribution
Detected through mass spectrometry, bioinformatics and emergent high-throughput mapping,
major RNA modification classes regulate molecular behaviors:
Methylation
- N6-methyladenosine (m6A), most abundant mammalian modification guiding mRNA fate.
- 2’-O-methylations stabilizing rRNAs, stabilizing cap structures.
Pseudouridylations
- Ψ modifications distributed across rRNAs, tRNAs, snoRNAs stabilizing secondary
structures.
Other Base Modifications
- Inosine (I), queuosine (Q), 5-methylcytidine regulating tRNAs, rRNAs.
Isopentenyladenosine (i6A)
- Modification guiding tRNA stability, structure in all domains of life.
Acetylation
- N6-acetyladenosine emerging as dynamic mRNA modification signal.
Besides endogenous modifications, external modifications introduced by toxins or UV
damage regulate stress responses. Overall, combinatorial RNA ‘epitranscriptomics’ through
widespread base and ribose modifications pervasively influence molecular functions.
RNA Modification Enzymes and their Mechanisms
Diverse enzyme classes install RNA modifications through sequence/structure-specific
recognition:
Methyltransferases
- S-adenosylmethionine-dependent enzymes mediate m6A, Ψ methylations and others.
Pseudouridine Synthases
- TRU/TruB family enzymes isomerize uridines to pseudouridines in tRNAs, rRNAs.
RNA Editases
- ADAR family deaminases mediating A-to-I editing in coding/non-coding RNAs.
Methylcytosine Dimethyltransferases
- Regulate m5C modifications guiding rRNA maturation, tRNA stability.
Ribose Methyltransferases
- Install 2’-O-methylations displaying broad phyletic conservation.
Acetyltransferases
- Writers mediate dynamic, regulated N6-acetyladenosine signaling.
Overall, diverse classes of RNA modification enzymes precisely tailor molecular functions
through recognition of sequence/structure contexts, advancing post-transcriptional regulatory
complexity across all domains. Their study promises novel insight across biology.
Roles of RNA Modifications in Gene Regulation
Combinatorial RNA modifications govern molecular processes through distinct mechanisms:
Alternative Splicing Regulation
- m6A recruits splicing factors guiding cotranscriptional intron removal decisions.
RNA Localization and Targeting
- m6A, Ψ guide transcripts to subcellular destinations like stress granules.
RNA Translation
- m6A near start/stop codons enhances translation. Pseudouridines stabilize tRNA structures.
RNA Stability
- 2’-O-methylations protect mRNA 5’/3’ ends from cleavage. Pseudouridines stabilize
tRNAs, rRNAs.
RNA Structuring
- Pseudouridines, isopentenyladenosine rigidify tRNA conformations guiding
aminoacylation.
Non-coding RNA Function
- m6A regulates lncRNA stability/processing. Pseudouridines stabilize sno/snRNAs guides.
Oxidative Stress Response
- N6-acetyladenosine dynamically regulates heat shock response transcripts.
Through combinatorial crosstalk between writer/reader/eraser proteins mediating installations
and interpretations, modifications add layers integrating RNA functionality with
environmental sensing and physiological signaling at whole-cell and organismal levels. The
discovery potential through epitranscriptomics remains exponential.
Roles in Development and Disease
RNA modification deregulation associates with developmental defects and disease through
impacts on molecular pathways:
- NSun2-mediated m5C deficiency impairs ribosome maturation and causes growth defects.
- FTO demethylase links obesity to dynamic m6A-dependent adipogenesis.
- ADAR1 deficiency causes A-to-I editing defects lethal to mice through innate immunity
failings.
- Virus hijacking/ inhibition of host m6A writers aids evasion of antiviral defenses.
- FTO, ALKBH5 dysregulation links m6A erasure defects to cancers through sustained
oncogene translation.
- TRNA modifications maintain proteostasis; defects influence neurological disorders and
METTL3 links m6A-dependent transcript stability to metastasis.
Overall, numerous genetic disorders emerge from unbalanced RNA modification
homeostasis. Deregulated epitranscriptome profiles arise across disease states, promising
novel diagnostic/prognostic biomarkers or therapeutic intervention strategies if regulatory
roles are clarified. Combinatorial “epitranscriptomic therapies” targeting RNA modifications
represent an emerging Precision Medicine frontier if impacts are deciphered.
High-Throughput Modification Mapping
Technological advances now globally map and quantify RNA modifications at single-
nucleotide resolution through:
- m6A-Seq and its variants couple anti-m6A antibody IP with deep sequencing.
- Pseudo-Seq couples anti-Ψ antibody with sequencing.
- MeRIP-Seq couples anti-methylated ribose IP with sequencing.
- RAM (RNA annotation and mapping) couples mass spectrometry with sequencing.
- CLIP-based methods map protein-RNA interactions.
- Ribosome profiling delineates modified transcript subsets.
- Multiomics integration clarifies regulatory interplay across molecules.
Overall, innovations delineate comprehensive landscape of RNA modifications influencing
transcriptome-wide gene expression, alternative splicing, localization and translation on a
system-wide scale in health and disease. The next wave involves functional validation
through epigenetic perturbations.
Frontiers and Future Directions
As technological and computational capabilities exponentially advance resolution into
regulatory RNA epitranscriptomes, frontiers emerge across diverse fields impacting Precision
Medicine and synthetic biology:
- Delineating tissue- and condition-specific epitranscriptomic maps guides biomarker,
therapeutic target discovery.
- Determining ‘writers’, ‘erasers’, ‘readers’ mediating RNA-protein interaction networks
governing development.
- Elucidating mechanisms precisely linking epitranscriptomic alterations to disease
pathogenesis and progression.
- Designing small molecule or CRISPR-based epitranscriptomic modulators precisely
targeting modifier enzymes.
- Applying targeted RNA modification patterning or temporal control of their dynamic
regulation.
- Synthesizing minimal genomes with non-natural modification incorporation capabilities.
- Combining modifications, alternative polyadenylation, editing in synthetic genetic circuits
with emergent behaviors.
- Characterizing intergenerational epitranscriptomic inheritance and non-Mendelian
transgenerational effects.
Progress depends upon accessible public databases, open science practices transparently
sharing resources unlocking complex regulatory mechanisms central to molecular, cellular
and system-wide understanding. Overall, epitranscriptomics represents a burgeoning ‘third
layer’ of regulatory complexity connecting gene expression control to environmental sensing,
development and programmed cellular states through nuanced combinatorial RNA post-
transcriptional programs.
Beyond its central roles encoding genetic information and serving as an intermediary between
DNA and protein synthesis, RNA itself represents a sophisticated regulatory network
controlling gene expression through extensive post-transcriptional modifications impacting
stability, localization and translation. Over 160 distinct chemical modifications fine-tune
ribosomal, transfer, messenger and non-coding RNA functionality across all domains of life.
These modifications, occurring through enzymes recognizing specific sequence/structural
motifs, influence molecular interactions determining developmental processes, signal
transduction, stress responses and disease states in ways recently coming into focus.
Nuanced roles of RNA modifications emerged through innovative strategies enabling high-
throughput mapping, as technologies advanced from two-dimensional gel electrophoresis
through mass spectrometry and deep sequencing. New methods delineate modification-
guided regulons determining molecular phenotypes. Key recent insights reveal how
combinatorial RNA modifications influence alternative splicing, RNA stability, targeting
pathways governing biological complexity, health and disease at the interface between
epigenetics and genomics. Their deregulation associates with developmental defects and
cancer etiology.
This review surveys major classes and regulators of RNA modifications across coding and
non-coding transcripts, their expanding functional landscape contributing to post-
transcriptional gene regulation, as well as exciting frontiers promising to clarify diverse
physiological roles and disease implications while inspiring novel therapeutic intervention
strategies. A deeper mechanistic understanding promises impacting scientific domains from
developmental biology to Precision Medicine through decoding long-overlooked layers of
complex regulatory programs.
RNA Modification Classes and their Distribution
Detected through mass spectrometry, bioinformatics and emergent high-throughput mapping,
major RNA modification classes regulate molecular behaviors:
Methylation
- N6-methyladenosine (m6A), most abundant mammalian modification guiding mRNA fate.
- 2’-O-methylations stabilizing rRNAs, stabilizing cap structures.
Pseudouridylations
- Ψ modifications distributed across rRNAs, tRNAs, snoRNAs stabilizing secondary
structures.
Other Base Modifications
- Inosine (I), queuosine (Q), 5-methylcytidine regulating tRNAs, rRNAs.
Isopentenyladenosine (i6A)
- Modification guiding tRNA stability, structure in all domains of life.
Acetylation
- N6-acetyladenosine emerging as dynamic mRNA modification signal.
Besides endogenous modifications, external modifications introduced by toxins or UV
damage regulate stress responses. Overall, combinatorial RNA ‘epitranscriptomics’ through
widespread base and ribose modifications pervasively influence molecular functions.
RNA Modification Enzymes and their Mechanisms
Diverse enzyme classes install RNA modifications through sequence/structure-specific
recognition:
Methyltransferases
- S-adenosylmethionine-dependent enzymes mediate m6A, Ψ methylations and others.
Pseudouridine Synthases
- TRU/TruB family enzymes isomerize uridines to pseudouridines in tRNAs, rRNAs.
RNA Editases
- ADAR family deaminases mediating A-to-I editing in coding/non-coding RNAs.
Methylcytosine Dimethyltransferases
- Regulate m5C modifications guiding rRNA maturation, tRNA stability.
Ribose Methyltransferases
- Install 2’-O-methylations displaying broad phyletic conservation.
Acetyltransferases
- Writers mediate dynamic, regulated N6-acetyladenosine signaling.
Overall, diverse classes of RNA modification enzymes precisely tailor molecular functions
through recognition of sequence/structure contexts, advancing post-transcriptional regulatory
complexity across all domains. Their study promises novel insight across biology.
Roles of RNA Modifications in Gene Regulation
Combinatorial RNA modifications govern molecular processes through distinct mechanisms:
Alternative Splicing Regulation
- m6A recruits splicing factors guiding cotranscriptional intron removal decisions.
RNA Localization and Targeting
- m6A, Ψ guide transcripts to subcellular destinations like stress granules.
RNA Translation
- m6A near start/stop codons enhances translation. Pseudouridines stabilize tRNA structures.
RNA Stability
- 2’-O-methylations protect mRNA 5’/3’ ends from cleavage. Pseudouridines stabilize
tRNAs, rRNAs.
RNA Structuring
- Pseudouridines, isopentenyladenosine rigidify tRNA conformations guiding
aminoacylation.
Non-coding RNA Function
- m6A regulates lncRNA stability/processing. Pseudouridines stabilize sno/snRNAs guides.
Oxidative Stress Response
- N6-acetyladenosine dynamically regulates heat shock response transcripts.
Through combinatorial crosstalk between writer/reader/eraser proteins mediating installations
and interpretations, modifications add layers integrating RNA functionality with
environmental sensing and physiological signaling at whole-cell and organismal levels. The
discovery potential through epitranscriptomics remains exponential.
Roles in Development and Disease
RNA modification deregulation associates with developmental defects and disease through
impacts on molecular pathways:
- NSun2-mediated m5C deficiency impairs ribosome maturation and causes growth defects.
- FTO demethylase links obesity to dynamic m6A-dependent adipogenesis.
- ADAR1 deficiency causes A-to-I editing defects lethal to mice through innate immunity
failings.
- Virus hijacking/ inhibition of host m6A writers aids evasion of antiviral defenses.
- FTO, ALKBH5 dysregulation links m6A erasure defects to cancers through sustained
oncogene translation.
- TRNA modifications maintain proteostasis; defects influence neurological disorders and
METTL3 links m6A-dependent transcript stability to metastasis.
Overall, numerous genetic disorders emerge from unbalanced RNA modification
homeostasis. Deregulated epitranscriptome profiles arise across disease states, promising
novel diagnostic/prognostic biomarkers or therapeutic intervention strategies if regulatory
roles are clarified. Combinatorial “epitranscriptomic therapies” targeting RNA modifications
represent an emerging Precision Medicine frontier if impacts are deciphered.
High-Throughput Modification Mapping
Technological advances now globally map and quantify RNA modifications at single-
nucleotide resolution through:
- m6A-Seq and its variants couple anti-m6A antibody IP with deep sequencing.
- Pseudo-Seq couples anti-Ψ antibody with sequencing.
- MeRIP-Seq couples anti-methylated ribose IP with sequencing.
- RAM (RNA annotation and mapping) couples mass spectrometry with sequencing.
- CLIP-based methods map protein-RNA interactions.
- Ribosome profiling delineates modified transcript subsets.
- Multiomics integration clarifies regulatory interplay across molecules.
Overall, innovations delineate comprehensive landscape of RNA modifications influencing
transcriptome-wide gene expression, alternative splicing, localization and translation on a
system-wide scale in health and disease. The next wave involves functional validation
through epigenetic perturbations.
Frontiers and Future Directions
As technological and computational capabilities exponentially advance resolution into
regulatory RNA epitranscriptomes, frontiers emerge across diverse fields impacting Precision
Medicine and synthetic biology:
- Delineating tissue- and condition-specific epitranscriptomic maps guides biomarker,
therapeutic target discovery.
- Determining ‘writers’, ‘erasers’, ‘readers’ mediating RNA-protein interaction networks
governing development.
- Elucidating mechanisms precisely linking epitranscriptomic alterations to disease
pathogenesis and progression.
- Designing small molecule or CRISPR-based epitranscriptomic modulators precisely
targeting modifier enzymes.
- Applying targeted RNA modification patterning or temporal control of their dynamic
regulation.
- Synthesizing minimal genomes with non-natural modification incorporation capabilities.
- Combining modifications, alternative polyadenylation, editing in synthetic genetic circuits
with emergent behaviors.
- Characterizing intergenerational epitranscriptomic inheritance and non-Mendelian
transgenerational effects.
Progress depends upon accessible public databases, open science practices transparently
sharing resources unlocking complex regulatory mechanisms central to molecular, cellular
and system-wide understanding. Overall, epitranscriptomics represents a burgeoning ‘third
layer’ of regulatory complexity connecting gene expression control to environmental sensing,
development and programmed cellular states through nuanced combinatorial RNA post-
transcriptional programs.
Beyond its central roles encoding genetic information and serving as an intermediary between
DNA and protein synthesis, RNA itself represents a sophisticated regulatory network
controlling gene expression through extensive post-transcriptional modifications impacting
stability, localization and translation. Over 160 distinct chemical modifications fine-tune
ribosomal, transfer, messenger and non-coding RNA functionality across all domains of life.
These modifications, occurring through enzymes recognizing specific sequence/structural
motifs, influence molecular interactions determining developmental processes, signal
transduction, stress responses and disease states in ways recently coming into focus.
Nuanced roles of RNA modifications emerged through innovative strategies enabling high-
throughput mapping, as technologies advanced from two-dimensional gel electrophoresis
through mass spectrometry and deep sequencing. New methods delineate modification-
guided regulons determining molecular phenotypes. Key recent insights reveal how
combinatorial RNA modifications influence alternative splicing, RNA stability, targeting
pathways governing biological complexity, health and disease at the interface between
epigenetics and genomics. Their deregulation associates with developmental defects and
cancer etiology.
This review surveys major classes and regulators of RNA modifications across coding and
non-coding transcripts, their expanding functional landscape contributing to post-
transcriptional gene regulation, as well as exciting frontiers promising to clarify diverse
physiological roles and disease implications while inspiring novel therapeutic intervention
strategies. A deeper mechanistic understanding promises impacting scientific domains from
developmental biology to Precision Medicine through decoding long-overlooked layers of
complex regulatory programs.
RNA Modification Classes and their Distribution
Detected through mass spectrometry, bioinformatics and emergent high-throughput mapping,
major RNA modification classes regulate molecular behaviors:
Methylation
- N6-methyladenosine (m6A), most abundant mammalian modification guiding mRNA fate.
- 2’-O-methylations stabilizing rRNAs, stabilizing cap structures.
Pseudouridylations
- Ψ modifications distributed across rRNAs, tRNAs, snoRNAs stabilizing secondary
structures.
Other Base Modifications
- Inosine (I), queuosine (Q), 5-methylcytidine regulating tRNAs, rRNAs.
Isopentenyladenosine (i6A)
- Modification guiding tRNA stability, structure in all domains of life.
Acetylation
- N6-acetyladenosine emerging as dynamic mRNA modification signal.
Besides endogenous modifications, external modifications introduced by toxins or UV
damage regulate stress responses. Overall, combinatorial RNA ‘epitranscriptomics’ through
widespread base and ribose modifications pervasively influence molecular functions.
RNA Modification Enzymes and their Mechanisms
Diverse enzyme classes install RNA modifications through sequence/structure-specific
recognition:
Methyltransferases
- S-adenosylmethionine-dependent enzymes mediate m6A, Ψ methylations and others.
Pseudouridine Synthases
- TRU/TruB family enzymes isomerize uridines to pseudouridines in tRNAs, rRNAs.
RNA Editases
- ADAR family deaminases mediating A-to-I editing in coding/non-coding RNAs.
Methylcytosine Dimethyltransferases
- Regulate m5C modifications guiding rRNA maturation, tRNA stability.
Ribose Methyltransferases
- Install 2’-O-methylations displaying broad phyletic conservation.
Acetyltransferases
- Writers mediate dynamic, regulated N6-acetyladenosine signaling.
Overall, diverse classes of RNA modification enzymes precisely tailor molecular functions
through recognition of sequence/structure contexts, advancing post-transcriptional regulatory
complexity across all domains. Their study promises novel insight across biology.
Roles of RNA Modifications in Gene Regulation
Combinatorial RNA modifications govern molecular processes through distinct mechanisms:
Alternative Splicing Regulation
- m6A recruits splicing factors guiding cotranscriptional intron removal decisions.
RNA Localization and Targeting
- m6A, Ψ guide transcripts to subcellular destinations like stress granules.
RNA Translation
- m6A near start/stop codons enhances translation. Pseudouridines stabilize tRNA structures.
RNA Stability
- 2’-O-methylations protect mRNA 5’/3’ ends from cleavage. Pseudouridines stabilize
tRNAs, rRNAs.
RNA Structuring
- Pseudouridines, isopentenyladenosine rigidify tRNA conformations guiding
aminoacylation.
Non-coding RNA Function
- m6A regulates lncRNA stability/processing. Pseudouridines stabilize sno/snRNAs guides.
Oxidative Stress Response
- N6-acetyladenosine dynamically regulates heat shock response transcripts.
Through combinatorial crosstalk between writer/reader/eraser proteins mediating installations
and interpretations, modifications add layers integrating RNA functionality with
environmental sensing and physiological signaling at whole-cell and organismal levels. The
discovery potential through epitranscriptomics remains exponential.
Roles in Development and Disease
RNA modification deregulation associates with developmental defects and disease through
impacts on molecular pathways:
- NSun2-mediated m5C deficiency impairs ribosome maturation and causes growth defects.
- FTO demethylase links obesity to dynamic m6A-dependent adipogenesis.
- ADAR1 deficiency causes A-to-I editing defects lethal to mice through innate immunity
failings.
- Virus hijacking/ inhibition of host m6A writers aids evasion of antiviral defenses.
- FTO, ALKBH5 dysregulation links m6A erasure defects to cancers through sustained
oncogene translation.
- TRNA modifications maintain proteostasis; defects influence neurological disorders and
METTL3 links m6A-dependent transcript stability to metastasis.
Overall, numerous genetic disorders emerge from unbalanced RNA modification
homeostasis. Deregulated epitranscriptome profiles arise across disease states, promising
novel diagnostic/prognostic biomarkers or therapeutic intervention strategies if regulatory
roles are clarified. Combinatorial “epitranscriptomic therapies” targeting RNA modifications
represent an emerging Precision Medicine frontier if impacts are deciphered.
High-Throughput Modification Mapping
Technological advances now globally map and quantify RNA modifications at single-
nucleotide resolution through:
- m6A-Seq and its variants couple anti-m6A antibody IP with deep sequencing.
- Pseudo-Seq couples anti-Ψ antibody with sequencing.
- MeRIP-Seq couples anti-methylated ribose IP with sequencing.
- RAM (RNA annotation and mapping) couples mass spectrometry with sequencing.
- CLIP-based methods map protein-RNA interactions.
- Ribosome profiling delineates modified transcript subsets.
- Multiomics integration clarifies regulatory interplay across molecules.
Overall, innovations delineate comprehensive landscape of RNA modifications influencing
transcriptome-wide gene expression, alternative splicing, localization and translation on a
system-wide scale in health and disease. The next wave involves functional validation
through epigenetic perturbations.
Frontiers and Future Directions
As technological and computational capabilities exponentially advance resolution into
regulatory RNA epitranscriptomes, frontiers emerge across diverse fields impacting Precision
Medicine and synthetic biology:
- Delineating tissue- and condition-specific epitranscriptomic maps guides biomarker,
therapeutic target discovery.
- Determining ‘writers’, ‘erasers’, ‘readers’ mediating RNA-protein interaction networks
governing development.
- Elucidating mechanisms precisely linking epitranscriptomic alterations to disease
pathogenesis and progression.
- Designing small molecule or CRISPR-based epitranscriptomic modulators precisely
targeting modifier enzymes.
- Applying targeted RNA modification patterning or temporal control of their dynamic
regulation.
- Synthesizing minimal genomes with non-natural modification incorporation capabilities.
- Combining modifications, alternative polyadenylation, editing in synthetic genetic circuits
with emergent behaviors.
- Characterizing intergenerational epitranscriptomic inheritance and non-Mendelian
transgenerational effects.
Progress depends upon accessible public databases, open science practices transparently
sharing resources unlocking complex regulatory mechanisms central to molecular, cellular
and system-wide understanding. Overall, epitranscriptomics represents a burgeoning ‘third
layer’ of regulatory complexity connecting gene expression control to environmental sensing,
development and programmed cellular states through nuanced combinatorial RNA post-
transcriptional programs.
Beyond its central roles encoding genetic information and serving as an intermediary between
DNA and protein synthesis, RNA itself represents a sophisticated regulatory network
controlling gene expression through extensive post-transcriptional modifications impacting
stability, localization and translation. Over 160 distinct chemical modifications fine-tune
ribosomal, transfer, messenger and non-coding RNA functionality across all domains of life.
These modifications, occurring through enzymes recognizing specific sequence/structural
motifs, influence molecular interactions determining developmental processes, signal
transduction, stress responses and disease states in ways recently coming into focus.
Nuanced roles of RNA modifications emerged through innovative strategies enabling high-
throughput mapping, as technologies advanced from two-dimensional gel electrophoresis
through mass spectrometry and deep sequencing. New methods delineate modification-
guided regulons determining molecular phenotypes. Key recent insights reveal how
combinatorial RNA modifications influence alternative splicing, RNA stability, targeting
pathways governing biological complexity, health and disease at the interface between
epigenetics and genomics. Their deregulation associates with developmental defects and
cancer etiology.
This review surveys major classes and regulators of RNA modifications across coding and
non-coding transcripts, their expanding functional landscape contributing to post-
transcriptional gene regulation, as well as exciting frontiers promising to clarify diverse
physiological roles and disease implications while inspiring novel therapeutic intervention
strategies. A deeper mechanistic understanding promises impacting scientific domains from
developmental biology to Precision Medicine through decoding long-overlooked layers of
complex regulatory programs.
RNA Modification Classes and their Distribution
Detected through mass spectrometry, bioinformatics and emergent high-throughput mapping,
major RNA modification classes regulate molecular behaviors:
Methylation
- N6-methyladenosine (m6A), most abundant mammalian modification guiding mRNA fate.
- 2’-O-methylations stabilizing rRNAs, stabilizing cap structures.
Pseudouridylations
- Ψ modifications distributed across rRNAs, tRNAs, snoRNAs stabilizing secondary
structures.
Other Base Modifications
- Inosine (I), queuosine (Q), 5-methylcytidine regulating tRNAs, rRNAs.
Isopentenyladenosine (i6A)
- Modification guiding tRNA stability, structure in all domains of life.
Acetylation
- N6-acetyladenosine emerging as dynamic mRNA modification signal.
Besides endogenous modifications, external modifications introduced by toxins or UV
damage regulate stress responses. Overall, combinatorial RNA ‘epitranscriptomics’ through
widespread base and ribose modifications pervasively influence molecular functions.
RNA Modification Enzymes and their Mechanisms
Diverse enzyme classes install RNA modifications through sequence/structure-specific
recognition:
Methyltransferases
- S-adenosylmethionine-dependent enzymes mediate m6A, Ψ methylations and others.
Pseudouridine Synthases
- TRU/TruB family enzymes isomerize uridines to pseudouridines in tRNAs, rRNAs.
RNA Editases
- ADAR family deaminases mediating A-to-I editing in coding/non-coding RNAs.
Methylcytosine Dimethyltransferases
- Regulate m5C modifications guiding rRNA maturation, tRNA stability.
Ribose Methyltransferases
- Install 2’-O-methylations displaying broad phyletic conservation.
Acetyltransferases
- Writers mediate dynamic, regulated N6-acetyladenosine signaling.
Overall, diverse classes of RNA modification enzymes precisely tailor molecular functions
through recognition of sequence/structure contexts, advancing post-transcriptional regulatory
complexity across all domains. Their study promises novel insight across biology.
Roles of RNA Modifications in Gene Regulation
Combinatorial RNA modifications govern molecular processes through distinct mechanisms:
Alternative Splicing Regulation
- m6A recruits splicing factors guiding cotranscriptional intron removal decisions.
RNA Localization and Targeting
- m6A, Ψ guide transcripts to subcellular destinations like stress granules.
RNA Translation
- m6A near start/stop codons enhances translation. Pseudouridines stabilize tRNA structures.
RNA Stability
- 2’-O-methylations protect mRNA 5’/3’ ends from cleavage. Pseudouridines stabilize
tRNAs, rRNAs.
RNA Structuring
- Pseudouridines, isopentenyladenosine rigidify tRNA conformations guiding
aminoacylation.
Non-coding RNA Function
- m6A regulates lncRNA stability/processing. Pseudouridines stabilize sno/snRNAs guides.
Oxidative Stress Response
- N6-acetyladenosine dynamically regulates heat shock response transcripts.
Through combinatorial crosstalk between writer/reader/eraser proteins mediating installations
and interpretations, modifications add layers integrating RNA functionality with
environmental sensing and physiological signaling at whole-cell and organismal levels. The
discovery potential through epitranscriptomics remains exponential.
Roles in Development and Disease
RNA modification deregulation associates with developmental defects and disease through
impacts on molecular pathways:
- NSun2-mediated m5C deficiency impairs ribosome maturation and causes growth defects.
- FTO demethylase links obesity to dynamic m6A-dependent adipogenesis.
- ADAR1 deficiency causes A-to-I editing defects lethal to mice through innate immunity
failings.
- Virus hijacking/ inhibition of host m6A writers aids evasion of antiviral defenses.
- FTO, ALKBH5 dysregulation links m6A erasure defects to cancers through sustained
oncogene translation.
- TRNA modifications maintain proteostasis; defects influence neurological disorders and
METTL3 links m6A-dependent transcript stability to metastasis.
Overall, numerous genetic disorders emerge from unbalanced RNA modification
homeostasis. Deregulated epitranscriptome profiles arise across disease states, promising
novel diagnostic/prognostic biomarkers or therapeutic intervention strategies if regulatory
roles are clarified. Combinatorial “epitranscriptomic therapies” targeting RNA modifications
represent an emerging Precision Medicine frontier if impacts are deciphered.
High-Throughput Modification Mapping
Technological advances now globally map and quantify RNA modifications at single-
nucleotide resolution through:
- m6A-Seq and its variants couple anti-m6A antibody IP with deep sequencing.
- Pseudo-Seq couples anti-Ψ antibody with sequencing.
- MeRIP-Seq couples anti-methylated ribose IP with sequencing.
- RAM (RNA annotation and mapping) couples mass spectrometry with sequencing.
- CLIP-based methods map protein-RNA interactions.
- Ribosome profiling delineates modified transcript subsets.
- Multiomics integration clarifies regulatory interplay across molecules.
Overall, innovations delineate comprehensive landscape of RNA modifications influencing
transcriptome-wide gene expression, alternative splicing, localization and translation on a
system-wide scale in health and disease. The next wave involves functional validation
through epigenetic perturbations.
Frontiers and Future Directions
As technological and computational capabilities exponentially advance resolution into
regulatory RNA epitranscriptomes, frontiers emerge across diverse fields impacting Precision
Medicine and synthetic biology:
- Delineating tissue- and condition-specific epitranscriptomic maps guides biomarker,
therapeutic target discovery.
- Determining ‘writers’, ‘erasers’, ‘readers’ mediating RNA-protein interaction networks
governing development.
- Elucidating mechanisms precisely linking epitranscriptomic alterations to disease
pathogenesis and progression.
- Designing small molecule or CRISPR-based epitranscriptomic modulators precisely
targeting modifier enzymes.
- Applying targeted RNA modification patterning or temporal control of their dynamic
regulation.
- Synthesizing minimal genomes with non-natural modification incorporation capabilities.
- Combining modifications, alternative polyadenylation, editing in synthetic genetic circuits
with emergent behaviors.
- Characterizing intergenerational epitranscriptomic inheritance and non-Mendelian
transgenerational effects.
Progress depends upon accessible public databases, open science practices transparently
sharing resources unlocking complex regulatory mechanisms central to molecular, cellular
and system-wide understanding. Overall, epitranscriptomics represents a burgeoning ‘third
layer’ of regulatory complexity connecting gene expression control to environmental sensing,
development and programmed cellular states through nuanced combinatorial RNA post-
transcriptional programs.
Beyond its central roles encoding genetic information and serving as an intermediary between
DNA and protein synthesis, RNA itself represents a sophisticated regulatory network
controlling gene expression through extensive post-transcriptional modifications impacting
stability, localization and translation. Over 160 distinct chemical modifications fine-tune
ribosomal, transfer, messenger and non-coding RNA functionality across all domains of life.
These modifications, occurring through enzymes recognizing specific sequence/structural
motifs, influence molecular interactions determining developmental processes, signal
transduction, stress responses and disease states in ways recently coming into focus.
Nuanced roles of RNA modifications emerged through innovative strategies enabling high-
throughput mapping, as technologies advanced from two-dimensional gel electrophoresis
through mass spectrometry and deep sequencing. New methods delineate modification-
guided regulons determining molecular phenotypes. Key recent insights reveal how
combinatorial RNA modifications influence alternative splicing, RNA stability, targeting
pathways governing biological complexity, health and disease at the interface between
epigenetics and genomics. Their deregulation associates with developmental defects and
cancer etiology.
This review surveys major classes and regulators of RNA modifications across coding and
non-coding transcripts, their expanding functional landscape contributing to post-
transcriptional gene regulation, as well as exciting frontiers promising to clarify diverse
physiological roles and disease implications while inspiring novel therapeutic intervention
strategies. A deeper mechanistic understanding promises impacting scientific domains from
developmental biology to Precision Medicine through decoding long-overlooked layers of
complex regulatory programs.
RNA Modification Classes and their Distribution
Detected through mass spectrometry, bioinformatics and emergent high-throughput mapping,
major RNA modification classes regulate molecular behaviors:
Methylation
- N6-methyladenosine (m6A), most abundant mammalian modification guiding mRNA fate.
- 2’-O-methylations stabilizing rRNAs, stabilizing cap structures.
Pseudouridylations
- Ψ modifications distributed across rRNAs, tRNAs, snoRNAs stabilizing secondary
structures.
Other Base Modifications
- Inosine (I), queuosine (Q), 5-methylcytidine regulating tRNAs, rRNAs.
Isopentenyladenosine (i6A)
- Modification guiding tRNA stability, structure in all domains of life.
Acetylation
- N6-acetyladenosine emerging as dynamic mRNA modification signal.
Besides endogenous modifications, external modifications introduced by toxins or UV
damage regulate stress responses. Overall, combinatorial RNA ‘epitranscriptomics’ through
widespread base and ribose modifications pervasively influence molecular functions.
RNA Modification Enzymes and their Mechanisms
Diverse enzyme classes install RNA modifications through sequence/structure-specific
recognition:
Methyltransferases
- S-adenosylmethionine-dependent enzymes mediate m6A, Ψ methylations and others.
Pseudouridine Synthases
- TRU/TruB family enzymes isomerize uridines to pseudouridines in tRNAs, rRNAs.
RNA Editases
- ADAR family deaminases mediating A-to-I editing in coding/non-coding RNAs.
Methylcytosine Dimethyltransferases
- Regulate m5C modifications guiding rRNA maturation, tRNA stability.
Ribose Methyltransferases
- Install 2’-O-methylations displaying broad phyletic conservation.
Acetyltransferases
- Writers mediate dynamic, regulated N6-acetyladenosine signaling.
Overall, diverse classes of RNA modification enzymes precisely tailor molecular functions
through recognition of sequence/structure contexts, advancing post-transcriptional regulatory
complexity across all domains. Their study promises novel insight across biology.
Roles of RNA Modifications in Gene Regulation
Combinatorial RNA modifications govern molecular processes through distinct mechanisms:
Alternative Splicing Regulation
- m6A recruits splicing factors guiding cotranscriptional intron removal decisions.
RNA Localization and Targeting
- m6A, Ψ guide transcripts to subcellular destinations like stress granules.
RNA Translation
- m6A near start/stop codons enhances translation. Pseudouridines stabilize tRNA structures.
RNA Stability
- 2’-O-methylations protect mRNA 5’/3’ ends from cleavage. Pseudouridines stabilize
tRNAs, rRNAs.
RNA Structuring
- Pseudouridines, isopentenyladenosine rigidify tRNA conformations guiding
aminoacylation.
Non-coding RNA Function
- m6A regulates lncRNA stability/processing. Pseudouridines stabilize sno/snRNAs guides.
Oxidative Stress Response
- N6-acetyladenosine dynamically regulates heat shock response transcripts.
Through combinatorial crosstalk between writer/reader/eraser proteins mediating installations
and interpretations, modifications add layers integrating RNA functionality with
environmental sensing and physiological signaling at whole-cell and organismal levels. The
discovery potential through epitranscriptomics remains exponential.
Roles in Development and Disease
RNA modification deregulation associates with developmental defects and disease through
impacts on molecular pathways:
- NSun2-mediated m5C deficiency impairs ribosome maturation and causes growth defects.
- FTO demethylase links obesity to dynamic m6A-dependent adipogenesis.
- ADAR1 deficiency causes A-to-I editing defects lethal to mice through innate immunity
failings.
- Virus hijacking/ inhibition of host m6A writers aids evasion of antiviral defenses.
- FTO, ALKBH5 dysregulation links m6A erasure defects to cancers through sustained
oncogene translation.
- TRNA modifications maintain proteostasis; defects influence neurological disorders and
METTL3 links m6A-dependent transcript stability to metastasis.
Overall, numerous genetic disorders emerge from unbalanced RNA modification
homeostasis. Deregulated epitranscriptome profiles arise across disease states, promising
novel diagnostic/prognostic biomarkers or therapeutic intervention strategies if regulatory
roles are clarified. Combinatorial “epitranscriptomic therapies” targeting RNA modifications
represent an emerging Precision Medicine frontier if impacts are deciphered.
High-Throughput Modification Mapping
Technological advances now globally map and quantify RNA modifications at single-
nucleotide resolution through:
- m6A-Seq and its variants couple anti-m6A antibody IP with deep sequencing.
- Pseudo-Seq couples anti-Ψ antibody with sequencing.
- MeRIP-Seq couples anti-methylated ribose IP with sequencing.
- RAM (RNA annotation and mapping) couples mass spectrometry with sequencing.
- CLIP-based methods map protein-RNA interactions.
- Ribosome profiling delineates modified transcript subsets.
- Multiomics integration clarifies regulatory interplay across molecules.
Overall, innovations delineate comprehensive landscape of RNA modifications influencing
transcriptome-wide gene expression, alternative splicing, localization and translation on a
system-wide scale in health and disease. The next wave involves functional validation
through epigenetic perturbations.
Frontiers and Future Directions
As technological and computational capabilities exponentially advance resolution into
regulatory RNA epitranscriptomes, frontiers emerge across diverse fields impacting Precision
Medicine and synthetic biology:
- Delineating tissue- and condition-specific epitranscriptomic maps guides biomarker,
therapeutic target discovery.
- Determining ‘writers’, ‘erasers’, ‘readers’ mediating RNA-protein interaction networks
governing development.
- Elucidating mechanisms precisely linking epitranscriptomic alterations to disease
pathogenesis and progression.
- Designing small molecule or CRISPR-based epitranscriptomic modulators precisely
targeting modifier enzymes.
- Applying targeted RNA modification patterning or temporal control of their dynamic
regulation.
- Synthesizing minimal genomes with non-natural modification incorporation capabilities.
- Combining modifications, alternative polyadenylation, editing in synthetic genetic circuits
with emergent behaviors.
- Characterizing intergenerational epitranscriptomic inheritance and non-Mendelian
transgenerational effects.
Progress depends upon accessible public databases, open science practices transparently
sharing resources unlocking complex regulatory mechanisms central to molecular, cellular
and system-wide understanding. Overall, epitranscriptomics represents a burgeoning ‘third
layer’ of regulatory complexity connecting gene expression control to environmental sensing,
development and programmed cellular states through nuanced combinatorial RNA post-
transcriptional programs.
Beyond its central roles encoding genetic information and serving as an intermediary between
DNA and protein synthesis, RNA itself represents a sophisticated regulatory network
controlling gene expression through extensive post-transcriptional modifications impacting
stability, localization and translation. Over 160 distinct chemical modifications fine-tune
ribosomal, transfer, messenger and non-coding RNA functionality across all domains of life.
These modifications, occurring through enzymes recognizing specific sequence/structural
motifs, influence molecular interactions determining developmental processes, signal
transduction, stress responses and disease states in ways recently coming into focus.
Nuanced roles of RNA modifications emerged through innovative strategies enabling high-
throughput mapping, as technologies advanced from two-dimensional gel electrophoresis
through mass spectrometry and deep sequencing. New methods delineate modification-
guided regulons determining molecular phenotypes. Key recent insights reveal how
combinatorial RNA modifications influence alternative splicing, RNA stability, targeting
pathways governing biological complexity, health and disease at the interface between
epigenetics and genomics. Their deregulation associates with developmental defects and
cancer etiology.
This review surveys major classes and regulators of RNA modifications across coding and
non-coding transcripts, their expanding functional landscape contributing to post-
transcriptional gene regulation, as well as exciting frontiers promising to clarify diverse
physiological roles and disease implications while inspiring novel therapeutic intervention
strategies. A deeper mechanistic understanding promises impacting scientific domains from
developmental biology to Precision Medicine through decoding long-overlooked layers of
complex regulatory programs.
RNA Modification Classes and their Distribution
Detected through mass spectrometry, bioinformatics and emergent high-throughput mapping,
major RNA modification classes regulate molecular behaviors:
Methylation
- N6-methyladenosine (m6A), most abundant mammalian modification guiding mRNA fate.
- 2’-O-methylations stabilizing rRNAs, stabilizing cap structures.
Pseudouridylations
- Ψ modifications distributed across rRNAs, tRNAs, snoRNAs stabilizing secondary
structures.
Other Base Modifications
- Inosine (I), queuosine (Q), 5-methylcytidine regulating tRNAs, rRNAs.
Isopentenyladenosine (i6A)
- Modification guiding tRNA stability, structure in all domains of life.
Acetylation
- N6-acetyladenosine emerging as dynamic mRNA modification signal.
Besides endogenous modifications, external modifications introduced by toxins or UV
damage regulate stress responses. Overall, combinatorial RNA ‘epitranscriptomics’ through
widespread base and ribose modifications pervasively influence molecular functions.
RNA Modification Enzymes and their Mechanisms
Diverse enzyme classes install RNA modifications through sequence/structure-specific
recognition:
Methyltransferases
- S-adenosylmethionine-dependent enzymes mediate m6A, Ψ methylations and others.
Pseudouridine Synthases
- TRU/TruB family enzymes isomerize uridines to pseudouridines in tRNAs, rRNAs.
RNA Editases
- ADAR family deaminases mediating A-to-I editing in coding/non-coding RNAs.
Methylcytosine Dimethyltransferases
- Regulate m5C modifications guiding rRNA maturation, tRNA stability.
Ribose Methyltransferases
- Install 2’-O-methylations displaying broad phyletic conservation.
Acetyltransferases
- Writers mediate dynamic, regulated N6-acetyladenosine signaling.
Overall, diverse classes of RNA modification enzymes precisely tailor molecular functions
through recognition of sequence/structure contexts, advancing post-transcriptional regulatory
complexity across all domains. Their study promises novel insight across biology.
Roles of RNA Modifications in Gene Regulation
Combinatorial RNA modifications govern molecular processes through distinct mechanisms:
Alternative Splicing Regulation
- m6A recruits splicing factors guiding cotranscriptional intron removal decisions.
RNA Localization and Targeting
- m6A, Ψ guide transcripts to subcellular destinations like stress granules.
RNA Translation
- m6A near start/stop codons enhances translation. Pseudouridines stabilize tRNA structures.
RNA Stability
- 2’-O-methylations protect mRNA 5’/3’ ends from cleavage. Pseudouridines stabilize
tRNAs, rRNAs.
RNA Structuring
- Pseudouridines, isopentenyladenosine rigidify tRNA conformations guiding
aminoacylation.
Non-coding RNA Function
- m6A regulates lncRNA stability/processing. Pseudouridines stabilize sno/snRNAs guides.
Oxidative Stress Response
- N6-acetyladenosine dynamically regulates heat shock response transcripts.
Through combinatorial crosstalk between writer/reader/eraser proteins mediating installations
and interpretations, modifications add layers integrating RNA functionality with
environmental sensing and physiological signaling at whole-cell and organismal levels. The
discovery potential through epitranscriptomics remains exponential.
Roles in Development and Disease
RNA modification deregulation associates with developmental defects and disease through
impacts on molecular pathways:
- NSun2-mediated m5C deficiency impairs ribosome maturation and causes growth defects.
- FTO demethylase links obesity to dynamic m6A-dependent adipogenesis.
- ADAR1 deficiency causes A-to-I editing defects lethal to mice through innate immunity
failings.
- Virus hijacking/ inhibition of host m6A writers aids evasion of antiviral defenses.
- FTO, ALKBH5 dysregulation links m6A erasure defects to cancers through sustained
oncogene translation.
- TRNA modifications maintain proteostasis; defects influence neurological disorders and
METTL3 links m6A-dependent transcript stability to metastasis.
Overall, numerous genetic disorders emerge from unbalanced RNA modification
homeostasis. Deregulated epitranscriptome profiles arise across disease states, promising
novel diagnostic/prognostic biomarkers or therapeutic intervention strategies if regulatory
roles are clarified. Combinatorial “epitranscriptomic therapies” targeting RNA modifications
represent an emerging Precision Medicine frontier if impacts are deciphered.
High-Throughput Modification Mapping
Technological advances now globally map and quantify RNA modifications at single-
nucleotide resolution through:
- m6A-Seq and its variants couple anti-m6A antibody IP with deep sequencing.
- Pseudo-Seq couples anti-Ψ antibody with sequencing.
- MeRIP-Seq couples anti-methylated ribose IP with sequencing.
- RAM (RNA annotation and mapping) couples mass spectrometry with sequencing.
- CLIP-based methods map protein-RNA interactions.
- Ribosome profiling delineates modified transcript subsets.
- Multiomics integration clarifies regulatory interplay across molecules.
Overall, innovations delineate comprehensive landscape of RNA modifications influencing
transcriptome-wide gene expression, alternative splicing, localization and translation on a
system-wide scale in health and disease. The next wave involves functional validation
through epigenetic perturbations.
Frontiers and Future Directions
As technological and computational capabilities exponentially advance resolution into
regulatory RNA epitranscriptomes, frontiers emerge across diverse fields impacting Precision
Medicine and synthetic biology:
- Delineating tissue- and condition-specific epitranscriptomic maps guides biomarker,
therapeutic target discovery.
- Determining ‘writers’, ‘erasers’, ‘readers’ mediating RNA-protein interaction networks
governing development.
- Elucidating mechanisms precisely linking epitranscriptomic alterations to disease
pathogenesis and progression.
- Designing small molecule or CRISPR-based epitranscriptomic modulators precisely
targeting modifier enzymes.
- Applying targeted RNA modification patterning or temporal control of their dynamic
regulation.
- Synthesizing minimal genomes with non-natural modification incorporation capabilities.
- Combining modifications, alternative polyadenylation, editing in synthetic genetic circuits
with emergent behaviors.
- Characterizing intergenerational epitranscriptomic inheritance and non-Mendelian
transgenerational effects.
Progress depends upon accessible public databases, open science practices transparently
sharing resources unlocking complex regulatory mechanisms central to molecular, cellular
and system-wide understanding. Overall, epitranscriptomics represents a burgeoning ‘third
layer’ of regulatory complexity connecting gene expression control to environmental sensing,
development and programmed cellular states through nuanced combinatorial RNA post-
transcriptional programs.
Beyond its central roles encoding genetic information and serving as an intermediary between
DNA and protein synthesis, RNA itself represents a sophisticated regulatory network
controlling gene expression through extensive post-transcriptional modifications impacting
stability, localization and translation. Over 160 distinct chemical modifications fine-tune
ribosomal, transfer, messenger and non-coding RNA functionality across all domains of life.
These modifications, occurring through enzymes recognizing specific sequence/structural
motifs, influence molecular interactions determining developmental processes, signal
transduction, stress responses and disease states in ways recently coming into focus.
Nuanced roles of RNA modifications emerged through innovative strategies enabling high-
throughput mapping, as technologies advanced from two-dimensional gel electrophoresis
through mass spectrometry and deep sequencing. New methods delineate modification-
guided regulons determining molecular phenotypes. Key recent insights reveal how
combinatorial RNA modifications influence alternative splicing, RNA stability, targeting
pathways governing biological complexity, health and disease at the interface between
epigenetics and genomics. Their deregulation associates with developmental defects and
cancer etiology.
This review surveys major classes and regulators of RNA modifications across coding and
non-coding transcripts, their expanding functional landscape contributing to post-
transcriptional gene regulation, as well as exciting frontiers promising to clarify diverse
physiological roles and disease implications while inspiring novel therapeutic intervention
strategies. A deeper mechanistic understanding promises impacting scientific domains from
developmental biology to Precision Medicine through decoding long-overlooked layers of
complex regulatory programs.
RNA Modification Classes and their Distribution
Detected through mass spectrometry, bioinformatics and emergent high-throughput mapping,
major RNA modification classes regulate molecular behaviors:
Methylation
- N6-methyladenosine (m6A), most abundant mammalian modification guiding mRNA fate.
- 2’-O-methylations stabilizing rRNAs, stabilizing cap structures.
Pseudouridylations
- Ψ modifications distributed across rRNAs, tRNAs, snoRNAs stabilizing secondary
structures.
Other Base Modifications
- Inosine (I), queuosine (Q), 5-methylcytidine regulating tRNAs, rRNAs.
Isopentenyladenosine (i6A)
- Modification guiding tRNA stability, structure in all domains of life.
Acetylation
- N6-acetyladenosine emerging as dynamic mRNA modification signal.
Besides endogenous modifications, external modifications introduced by toxins or UV
damage regulate stress responses. Overall, combinatorial RNA ‘epitranscriptomics’ through
widespread base and ribose modifications pervasively influence molecular functions.
RNA Modification Enzymes and their Mechanisms
Diverse enzyme classes install RNA modifications through sequence/structure-specific
recognition:
Methyltransferases
- S-adenosylmethionine-dependent enzymes mediate m6A, Ψ methylations and others.
Pseudouridine Synthases
- TRU/TruB family enzymes isomerize uridines to pseudouridines in tRNAs, rRNAs.
RNA Editases
- ADAR family deaminases mediating A-to-I editing in coding/non-coding RNAs.
Methylcytosine Dimethyltransferases
- Regulate m5C modifications guiding rRNA maturation, tRNA stability.
Ribose Methyltransferases
- Install 2’-O-methylations displaying broad phyletic conservation.
Acetyltransferases
- Writers mediate dynamic, regulated N6-acetyladenosine signaling.
Overall, diverse classes of RNA modification enzymes precisely tailor molecular functions
through recognition of sequence/structure contexts, advancing post-transcriptional regulatory
complexity across all domains. Their study promises novel insight across biology.
Roles of RNA Modifications in Gene Regulation
Combinatorial RNA modifications govern molecular processes through distinct mechanisms:
Alternative Splicing Regulation
- m6A recruits splicing factors guiding cotranscriptional intron removal decisions.
RNA Localization and Targeting
- m6A, Ψ guide transcripts to subcellular destinations like stress granules.
RNA Translation
- m6A near start/stop codons enhances translation. Pseudouridines stabilize tRNA structures.
RNA Stability
- 2’-O-methylations protect mRNA 5’/3’ ends from cleavage. Pseudouridines stabilize
tRNAs, rRNAs.
RNA Structuring
- Pseudouridines, isopentenyladenosine rigidify tRNA conformations guiding
aminoacylation.
Non-coding RNA Function
- m6A regulates lncRNA stability/processing. Pseudouridines stabilize sno/snRNAs guides.
Oxidative Stress Response
- N6-acetyladenosine dynamically regulates heat shock response transcripts.
Through combinatorial crosstalk between writer/reader/eraser proteins mediating installations
and interpretations, modifications add layers integrating RNA functionality with
environmental sensing and physiological signaling at whole-cell and organismal levels. The
discovery potential through epitranscriptomics remains exponential.
Roles in Development and Disease
RNA modification deregulation associates with developmental defects and disease through
impacts on molecular pathways:
- NSun2-mediated m5C deficiency impairs ribosome maturation and causes growth defects.
- FTO demethylase links obesity to dynamic m6A-dependent adipogenesis.
- ADAR1 deficiency causes A-to-I editing defects lethal to mice through innate immunity
failings.
- Virus hijacking/ inhibition of host m6A writers aids evasion of antiviral defenses.
- FTO, ALKBH5 dysregulation links m6A erasure defects to cancers through sustained
oncogene translation.
- TRNA modifications maintain proteostasis; defects influence neurological disorders and
METTL3 links m6A-dependent transcript stability to metastasis.
Overall, numerous genetic disorders emerge from unbalanced RNA modification
homeostasis. Deregulated epitranscriptome profiles arise across disease states, promising
novel diagnostic/prognostic biomarkers or therapeutic intervention strategies if regulatory
roles are clarified. Combinatorial “epitranscriptomic therapies” targeting RNA modifications
represent an emerging Precision Medicine frontier if impacts are deciphered.
High-Throughput Modification Mapping
Technological advances now globally map and quantify RNA modifications at single-
nucleotide resolution through:
- m6A-Seq and its variants couple anti-m6A antibody IP with deep sequencing.
- Pseudo-Seq couples anti-Ψ antibody with sequencing.
- MeRIP-Seq couples anti-methylated ribose IP with sequencing.
- RAM (RNA annotation and mapping) couples mass spectrometry with sequencing.
- CLIP-based methods map protein-RNA interactions.
- Ribosome profiling delineates modified transcript subsets.
- Multiomics integration clarifies regulatory interplay across molecules.
Overall, innovations delineate comprehensive landscape of RNA modifications influencing
transcriptome-wide gene expression, alternative splicing, localization and translation on a
system-wide scale in health and disease. The next wave involves functional validation
through epigenetic perturbations.
Frontiers and Future Directions
As technological and computational capabilities exponentially advance resolution into
regulatory RNA epitranscriptomes, frontiers emerge across diverse fields impacting Precision
Medicine and synthetic biology:
- Delineating tissue- and condition-specific epitranscriptomic maps guides biomarker,
therapeutic target discovery.
- Determining ‘writers’, ‘erasers’, ‘readers’ mediating RNA-protein interaction networks
governing development.
- Elucidating mechanisms precisely linking epitranscriptomic alterations to disease
pathogenesis and progression.
- Designing small molecule or CRISPR-based epitranscriptomic modulators precisely
targeting modifier enzymes.
- Applying targeted RNA modification patterning or temporal control of their dynamic
regulation.
- Synthesizing minimal genomes with non-natural modification incorporation capabilities.
- Combining modifications, alternative polyadenylation, editing in synthetic genetic circuits
with emergent behaviors.
- Characterizing intergenerational epitranscriptomic inheritance and non-Mendelian
transgenerational effects.
Progress depends upon accessible public databases, open science practices transparently
sharing resources unlocking complex regulatory mechanisms central to molecular, cellular
and system-wide understanding. Overall, epitranscriptomics represents a burgeoning ‘third
layer’ of regulatory complexity connecting gene expression control to environmental sensing,
development and programmed cellular states through nuanced combinatorial RNA post-
transcriptional programs.
Beyond its central roles encoding genetic information and serving as an intermediary between
DNA and protein synthesis, RNA itself represents a sophisticated regulatory network
controlling gene expression through extensive post-transcriptional modifications impacting
stability, localization and translation. Over 160 distinct chemical modifications fine-tune
ribosomal, transfer, messenger and non-coding RNA functionality across all domains of life.
These modifications, occurring through enzymes recognizing specific sequence/structural
motifs, influence molecular interactions determining developmental processes, signal
transduction, stress responses and disease states in ways recently coming into focus.
Nuanced roles of RNA modifications emerged through innovative strategies enabling high-
throughput mapping, as technologies advanced from two-dimensional gel electrophoresis
through mass spectrometry and deep sequencing. New methods delineate modification-
guided regulons determining molecular phenotypes. Key recent insights reveal how
combinatorial RNA modifications influence alternative splicing, RNA stability, targeting
pathways governing biological complexity, health and disease at the interface between
epigenetics and genomics. Their deregulation associates with developmental defects and
cancer etiology.
This review surveys major classes and regulators of RNA modifications across coding and
non-coding transcripts, their expanding functional landscape contributing to post-
transcriptional gene regulation, as well as exciting frontiers promising to clarify diverse
physiological roles and disease implications while inspiring novel therapeutic intervention
strategies. A deeper mechanistic understanding promises impacting scientific domains from
developmental biology to Precision Medicine through decoding long-overlooked layers of
complex regulatory programs.
RNA Modification Classes and their Distribution
Detected through mass spectrometry, bioinformatics and emergent high-throughput mapping,
major RNA modification classes regulate molecular behaviors:
Methylation
- N6-methyladenosine (m6A), most abundant mammalian modification guiding mRNA fate.
- 2’-O-methylations stabilizing rRNAs, stabilizing cap structures.
Pseudouridylations
- Ψ modifications distributed across rRNAs, tRNAs, snoRNAs stabilizing secondary
structures.
Other Base Modifications
- Inosine (I), queuosine (Q), 5-methylcytidine regulating tRNAs, rRNAs.
Isopentenyladenosine (i6A)
- Modification guiding tRNA stability, structure in all domains of life.
Acetylation
- N6-acetyladenosine emerging as dynamic mRNA modification signal.
Besides endogenous modifications, external modifications introduced by toxins or UV
damage regulate stress responses. Overall, combinatorial RNA ‘epitranscriptomics’ through
widespread base and ribose modifications pervasively influence molecular functions.
RNA Modification Enzymes and their Mechanisms
Diverse enzyme classes install RNA modifications through sequence/structure-specific
recognition:
Methyltransferases
- S-adenosylmethionine-dependent enzymes mediate m6A, Ψ methylations and others.
Pseudouridine Synthases
- TRU/TruB family enzymes isomerize uridines to pseudouridines in tRNAs, rRNAs.
RNA Editases
- ADAR family deaminases mediating A-to-I editing in coding/non-coding RNAs.
Methylcytosine Dimethyltransferases
- Regulate m5C modifications guiding rRNA maturation, tRNA stability.
Ribose Methyltransferases
- Install 2’-O-methylations displaying broad phyletic conservation.
Acetyltransferases
- Writers mediate dynamic, regulated N6-acetyladenosine signaling.
Overall, diverse classes of RNA modification enzymes precisely tailor molecular functions
through recognition of sequence/structure contexts, advancing post-transcriptional regulatory
complexity across all domains. Their study promises novel insight across biology.
Roles of RNA Modifications in Gene Regulation
Combinatorial RNA modifications govern molecular processes through distinct mechanisms:
Alternative Splicing Regulation
- m6A recruits splicing factors guiding cotranscriptional intron removal decisions.
RNA Localization and Targeting
- m6A, Ψ guide transcripts to subcellular destinations like stress granules.
RNA Translation
- m6A near start/stop codons enhances translation. Pseudouridines stabilize tRNA structures.
RNA Stability
- 2’-O-methylations protect mRNA 5’/3’ ends from cleavage. Pseudouridines stabilize
tRNAs, rRNAs.
RNA Structuring
- Pseudouridines, isopentenyladenosine rigidify tRNA conformations guiding
aminoacylation.
Non-coding RNA Function
- m6A regulates lncRNA stability/processing. Pseudouridines stabilize sno/snRNAs guides.
Oxidative Stress Response
- N6-acetyladenosine dynamically regulates heat shock response transcripts.
Through combinatorial crosstalk between writer/reader/eraser proteins mediating installations
and interpretations, modifications add layers integrating RNA functionality with
environmental sensing and physiological signaling at whole-cell and organismal levels. The
discovery potential through epitranscriptomics remains exponential.
Roles in Development and Disease
RNA modification deregulation associates with developmental defects and disease through
impacts on molecular pathways:
- NSun2-mediated m5C deficiency impairs ribosome maturation and causes growth defects.
- FTO demethylase links obesity to dynamic m6A-dependent adipogenesis.
- ADAR1 deficiency causes A-to-I editing defects lethal to mice through innate immunity
failings.
- Virus hijacking/ inhibition of host m6A writers aids evasion of antiviral defenses.
- FTO, ALKBH5 dysregulation links m6A erasure defects to cancers through sustained
oncogene translation.
- TRNA modifications maintain proteostasis; defects influence neurological disorders and
METTL3 links m6A-dependent transcript stability to metastasis.
Overall, numerous genetic disorders emerge from unbalanced RNA modification
homeostasis. Deregulated epitranscriptome profiles arise across disease states, promising
novel diagnostic/prognostic biomarkers or therapeutic intervention strategies if regulatory
roles are clarified. Combinatorial “epitranscriptomic therapies” targeting RNA modifications
represent an emerging Precision Medicine frontier if impacts are deciphered.
High-Throughput Modification Mapping
Technological advances now globally map and quantify RNA modifications at single-
nucleotide resolution through:
- m6A-Seq and its variants couple anti-m6A antibody IP with deep sequencing.
- Pseudo-Seq couples anti-Ψ antibody with sequencing.
- MeRIP-Seq couples anti-methylated ribose IP with sequencing.
- RAM (RNA annotation and mapping) couples mass spectrometry with sequencing.
- CLIP-based methods map protein-RNA interactions.
- Ribosome profiling delineates modified transcript subsets.
- Multiomics integration clarifies regulatory interplay across molecules.
Overall, innovations delineate comprehensive landscape of RNA modifications influencing
transcriptome-wide gene expression, alternative splicing, localization and translation on a
system-wide scale in health and disease. The next wave involves functional validation
through epigenetic perturbations.
Frontiers and Future Directions
As technological and computational capabilities exponentially advance resolution into
regulatory RNA epitranscriptomes, frontiers emerge across diverse fields impacting Precision
Medicine and synthetic biology:
- Delineating tissue- and condition-specific epitranscriptomic maps guides biomarker,
therapeutic target discovery.
- Determining ‘writers’, ‘erasers’, ‘readers’ mediating RNA-protein interaction networks
governing development.
- Elucidating mechanisms precisely linking epitranscriptomic alterations to disease
pathogenesis and progression.
- Designing small molecule or CRISPR-based epitranscriptomic modulators precisely
targeting modifier enzymes.
- Applying targeted RNA modification patterning or temporal control of their dynamic
regulation.
- Synthesizing minimal genomes with non-natural modification incorporation capabilities.
- Combining modifications, alternative polyadenylation, editing in synthetic genetic circuits
with emergent behaviors.
- Characterizing intergenerational epitranscriptomic inheritance and non-Mendelian
transgenerational effects.
Progress depends upon accessible public databases, open science practices transparently
sharing resources unlocking complex regulatory mechanisms central to molecular, cellular
and system-wide understanding. Overall, epitranscriptomics represents a burgeoning ‘third
layer’ of regulatory complexity connecting gene expression control to environmental sensing,
development and programmed cellular states through nuanced combinatorial RNA post-
transcriptional programs.
Beyond its central roles encoding genetic information and serving as an intermediary between
DNA and protein synthesis, RNA itself represents a sophisticated regulatory network
controlling gene expression through extensive post-transcriptional modifications impacting
stability, localization and translation. Over 160 distinct chemical modifications fine-tune
ribosomal, transfer, messenger and non-coding RNA functionality across all domains of life.
These modifications, occurring through enzymes recognizing specific sequence/structural
motifs, influence molecular interactions determining developmental processes, signal
transduction, stress responses and disease states in ways recently coming into focus.
Nuanced roles of RNA modifications emerged through innovative strategies enabling high-
throughput mapping, as technologies advanced from two-dimensional gel electrophoresis
through mass spectrometry and deep sequencing. New methods delineate modification-
guided regulons determining molecular phenotypes. Key recent insights reveal how
combinatorial RNA modifications influence alternative splicing, RNA stability, targeting
pathways governing biological complexity, health and disease at the interface between
epigenetics and genomics. Their deregulation associates with developmental defects and
cancer etiology.
This review surveys major classes and regulators of RNA modifications across coding and
non-coding transcripts, their expanding functional landscape contributing to post-
transcriptional gene regulation, as well as exciting frontiers promising to clarify diverse
physiological roles and disease implications while inspiring novel therapeutic intervention
strategies. A deeper mechanistic understanding promises impacting scientific domains from
developmental biology to Precision Medicine through decoding long-overlooked layers of
complex regulatory programs.
RNA Modification Classes and their Distribution
Detected through mass spectrometry, bioinformatics and emergent high-throughput mapping,
major RNA modification classes regulate molecular behaviors:
Methylation
- N6-methyladenosine (m6A), most abundant mammalian modification guiding mRNA fate.
- 2’-O-methylations stabilizing rRNAs, stabilizing cap structures.
Pseudouridylations
- Ψ modifications distributed across rRNAs, tRNAs, snoRNAs stabilizing secondary
structures.
Other Base Modifications
- Inosine (I), queuosine (Q), 5-methylcytidine regulating tRNAs, rRNAs.
Isopentenyladenosine (i6A)
- Modification guiding tRNA stability, structure in all domains of life.
Acetylation
- N6-acetyladenosine emerging as dynamic mRNA modification signal.
Besides endogenous modifications, external modifications introduced by toxins or UV
damage regulate stress responses. Overall, combinatorial RNA ‘epitranscriptomics’ through
widespread base and ribose modifications pervasively influence molecular functions.
RNA Modification Enzymes and their Mechanisms
Diverse enzyme classes install RNA modifications through sequence/structure-specific
recognition:
Methyltransferases
- S-adenosylmethionine-dependent enzymes mediate m6A, Ψ methylations and others.
Pseudouridine Synthases
- TRU/TruB family enzymes isomerize uridines to pseudouridines in tRNAs, rRNAs.
RNA Editases
- ADAR family deaminases mediating A-to-I editing in coding/non-coding RNAs.
Methylcytosine Dimethyltransferases
- Regulate m5C modifications guiding rRNA maturation, tRNA stability.
Ribose Methyltransferases
- Install 2’-O-methylations displaying broad phyletic conservation.
Acetyltransferases
- Writers mediate dynamic, regulated N6-acetyladenosine signaling.
Overall, diverse classes of RNA modification enzymes precisely tailor molecular functions
through recognition of sequence/structure contexts, advancing post-transcriptional regulatory
complexity across all domains. Their study promises novel insight across biology.
Roles of RNA Modifications in Gene Regulation
Combinatorial RNA modifications govern molecular processes through distinct mechanisms:
Alternative Splicing Regulation
- m6A recruits splicing factors guiding cotranscriptional intron removal decisions.
RNA Localization and Targeting
- m6A, Ψ guide transcripts to subcellular destinations like stress granules.
RNA Translation
- m6A near start/stop codons enhances translation. Pseudouridines stabilize tRNA structures.
RNA Stability
- 2’-O-methylations protect mRNA 5’/3’ ends from cleavage. Pseudouridines stabilize
tRNAs, rRNAs.
RNA Structuring
- Pseudouridines, isopentenyladenosine rigidify tRNA conformations guiding
aminoacylation.
Non-coding RNA Function
- m6A regulates lncRNA stability/processing. Pseudouridines stabilize sno/snRNAs guides.
Oxidative Stress Response
- N6-acetyladenosine dynamically regulates heat shock response transcripts.
Through combinatorial crosstalk between writer/reader/eraser proteins mediating installations
and interpretations, modifications add layers integrating RNA functionality with
environmental sensing and physiological signaling at whole-cell and organismal levels. The
discovery potential through epitranscriptomics remains exponential.
Roles in Development and Disease
RNA modification deregulation associates with developmental defects and disease through
impacts on molecular pathways:
- NSun2-mediated m5C deficiency impairs ribosome maturation and causes growth defects.
- FTO demethylase links obesity to dynamic m6A-dependent adipogenesis.
- ADAR1 deficiency causes A-to-I editing defects lethal to mice through innate immunity
failings.
- Virus hijacking/ inhibition of host m6A writers aids evasion of antiviral defenses.
- FTO, ALKBH5 dysregulation links m6A erasure defects to cancers through sustained
oncogene translation.
- TRNA modifications maintain proteostasis; defects influence neurological disorders and
METTL3 links m6A-dependent transcript stability to metastasis.
Overall, numerous genetic disorders emerge from unbalanced RNA modification
homeostasis. Deregulated epitranscriptome profiles arise across disease states, promising
novel diagnostic/prognostic biomarkers or therapeutic intervention strategies if regulatory
roles are clarified. Combinatorial “epitranscriptomic therapies” targeting RNA modifications
represent an emerging Precision Medicine frontier if impacts are deciphered.
High-Throughput Modification Mapping
Technological advances now globally map and quantify RNA modifications at single-
nucleotide resolution through:
- m6A-Seq and its variants couple anti-m6A antibody IP with deep sequencing.
- Pseudo-Seq couples anti-Ψ antibody with sequencing.
- MeRIP-Seq couples anti-methylated ribose IP with sequencing.
- RAM (RNA annotation and mapping) couples mass spectrometry with sequencing.
- CLIP-based methods map protein-RNA interactions.
- Ribosome profiling delineates modified transcript subsets.
- Multiomics integration clarifies regulatory interplay across molecules.
Overall, innovations delineate comprehensive landscape of RNA modifications influencing
transcriptome-wide gene expression, alternative splicing, localization and translation on a
system-wide scale in health and disease. The next wave involves functional validation
through epigenetic perturbations.
Frontiers and Future Directions
As technological and computational capabilities exponentially advance resolution into
regulatory RNA epitranscriptomes, frontiers emerge across diverse fields impacting Precision
Medicine and synthetic biology:
- Delineating tissue- and condition-specific epitranscriptomic maps guides biomarker,
therapeutic target discovery.
- Determining ‘writers’, ‘erasers’, ‘readers’ mediating RNA-protein interaction networks
governing development.
- Elucidating mechanisms precisely linking epitranscriptomic alterations to disease
pathogenesis and progression.
- Designing small molecule or CRISPR-based epitranscriptomic modulators precisely
targeting modifier enzymes.
- Applying targeted RNA modification patterning or temporal control of their dynamic
regulation.
- Synthesizing minimal genomes with non-natural modification incorporation capabilities.
- Combining modifications, alternative polyadenylation, editing in synthetic genetic circuits
with emergent behaviors.
- Characterizing intergenerational epitranscriptomic inheritance and non-Mendelian
transgenerational effects.
Progress depends upon accessible public databases, open science practices transparently
sharing resources unlocking complex regulatory mechanisms central to molecular, cellular
and system-wide understanding. Overall, epitranscriptomics represents a burgeoning ‘third
layer’ of regulatory complexity connecting gene expression control to environmental sensing,
development and programmed cellular states through nuanced combinatorial RNA post-
transcriptional programs.
Beyond its central roles encoding genetic information and serving as an intermediary between
DNA and protein synthesis, RNA itself represents a sophisticated regulatory network
controlling gene expression through extensive post-transcriptional modifications impacting
stability, localization and translation. Over 160 distinct chemical modifications fine-tune
ribosomal, transfer, messenger and non-coding RNA functionality across all domains of life.
These modifications, occurring through enzymes recognizing specific sequence/structural
motifs, influence molecular interactions determining developmental processes, signal
transduction, stress responses and disease states in ways recently coming into focus.
Nuanced roles of RNA modifications emerged through innovative strategies enabling high-
throughput mapping, as technologies advanced from two-dimensional gel electrophoresis
through mass spectrometry and deep sequencing. New methods delineate modification-
guided regulons determining molecular phenotypes. Key recent insights reveal how
combinatorial RNA modifications influence alternative splicing, RNA stability, targeting
pathways governing biological complexity, health and disease at the interface between
epigenetics and genomics. Their deregulation associates with developmental defects and
cancer etiology.
This review surveys major classes and regulators of RNA modifications across coding and
non-coding transcripts, their expanding functional landscape contributing to post-
transcriptional gene regulation, as well as exciting frontiers promising to clarify diverse
physiological roles and disease implications while inspiring novel therapeutic intervention
strategies. A deeper mechanistic understanding promises impacting scientific domains from
developmental biology to Precision Medicine through decoding long-overlooked layers of
complex regulatory programs.
RNA Modification Classes and their Distribution
Detected through mass spectrometry, bioinformatics and emergent high-throughput mapping,
major RNA modification classes regulate molecular behaviors:
Methylation
- N6-methyladenosine (m6A), most abundant mammalian modification guiding mRNA fate.
- 2’-O-methylations stabilizing rRNAs, stabilizing cap structures.
Pseudouridylations
- Ψ modifications distributed across rRNAs, tRNAs, snoRNAs stabilizing secondary
structures.
Other Base Modifications
- Inosine (I), queuosine (Q), 5-methylcytidine regulating tRNAs, rRNAs.
Isopentenyladenosine (i6A)
- Modification guiding tRNA stability, structure in all domains of life.
Acetylation
- N6-acetyladenosine emerging as dynamic mRNA modification signal.
Besides endogenous modifications, external modifications introduced by toxins or UV
damage regulate stress responses. Overall, combinatorial RNA ‘epitranscriptomics’ through
widespread base and ribose modifications pervasively influence molecular functions.
RNA Modification Enzymes and their Mechanisms
Diverse enzyme classes install RNA modifications through sequence/structure-specific
recognition:
Methyltransferases
- S-adenosylmethionine-dependent enzymes mediate m6A, Ψ methylations and others.
Pseudouridine Synthases
- TRU/TruB family enzymes isomerize uridines to pseudouridines in tRNAs, rRNAs.
RNA Editases
- ADAR family deaminases mediating A-to-I editing in coding/non-coding RNAs.
Methylcytosine Dimethyltransferases
- Regulate m5C modifications guiding rRNA maturation, tRNA stability.
Ribose Methyltransferases
- Install 2’-O-methylations displaying broad phyletic conservation.
Acetyltransferases
- Writers mediate dynamic, regulated N6-acetyladenosine signaling.
Overall, diverse classes of RNA modification enzymes precisely tailor molecular functions
through recognition of sequence/structure contexts, advancing post-transcriptional regulatory
complexity across all domains. Their study promises novel insight across biology.
Roles of RNA Modifications in Gene Regulation
Combinatorial RNA modifications govern molecular processes through distinct mechanisms:
Alternative Splicing Regulation
- m6A recruits splicing factors guiding cotranscriptional intron removal decisions.
RNA Localization and Targeting
- m6A, Ψ guide transcripts to subcellular destinations like stress granules.
RNA Translation
- m6A near start/stop codons enhances translation. Pseudouridines stabilize tRNA structures.
RNA Stability
- 2’-O-methylations protect mRNA 5’/3’ ends from cleavage. Pseudouridines stabilize
tRNAs, rRNAs.
RNA Structuring
- Pseudouridines, isopentenyladenosine rigidify tRNA conformations guiding
aminoacylation.
Non-coding RNA Function
- m6A regulates lncRNA stability/processing. Pseudouridines stabilize sno/snRNAs guides.
Oxidative Stress Response
- N6-acetyladenosine dynamically regulates heat shock response transcripts.
Through combinatorial crosstalk between writer/reader/eraser proteins mediating installations
and interpretations, modifications add layers integrating RNA functionality with
environmental sensing and physiological signaling at whole-cell and organismal levels. The
discovery potential through epitranscriptomics remains exponential.
Roles in Development and Disease
RNA modification deregulation associates with developmental defects and disease through
impacts on molecular pathways:
- NSun2-mediated m5C deficiency impairs ribosome maturation and causes growth defects.
- FTO demethylase links obesity to dynamic m6A-dependent adipogenesis.
- ADAR1 deficiency causes A-to-I editing defects lethal to mice through innate immunity
failings.
- Virus hijacking/ inhibition of host m6A writers aids evasion of antiviral defenses.
- FTO, ALKBH5 dysregulation links m6A erasure defects to cancers through sustained
oncogene translation.
- TRNA modifications maintain proteostasis; defects influence neurological disorders and
METTL3 links m6A-dependent transcript stability to metastasis.
Overall, numerous genetic disorders emerge from unbalanced RNA modification
homeostasis. Deregulated epitranscriptome profiles arise across disease states, promising
novel diagnostic/prognostic biomarkers or therapeutic intervention strategies if regulatory
roles are clarified. Combinatorial “epitranscriptomic therapies” targeting RNA modifications
represent an emerging Precision Medicine frontier if impacts are deciphered.
High-Throughput Modification Mapping
Technological advances now globally map and quantify RNA modifications at single-
nucleotide resolution through:
- m6A-Seq and its variants couple anti-m6A antibody IP with deep sequencing.
- Pseudo-Seq couples anti-Ψ antibody with sequencing.
- MeRIP-Seq couples anti-methylated ribose IP with sequencing.
- RAM (RNA annotation and mapping) couples mass spectrometry with sequencing.
- CLIP-based methods map protein-RNA interactions.
- Ribosome profiling delineates modified transcript subsets.
- Multiomics integration clarifies regulatory interplay across molecules.
Overall, innovations delineate comprehensive landscape of RNA modifications influencing
transcriptome-wide gene expression, alternative splicing, localization and translation on a
system-wide scale in health and disease. The next wave involves functional validation
through epigenetic perturbations.
Frontiers and Future Directions
As technological and computational capabilities exponentially advance resolution into
regulatory RNA epitranscriptomes, frontiers emerge across diverse fields impacting Precision
Medicine and synthetic biology:
- Delineating tissue- and condition-specific epitranscriptomic maps guides biomarker,
therapeutic target discovery.
- Determining ‘writers’, ‘erasers’, ‘readers’ mediating RNA-protein interaction networks
governing development.
- Elucidating mechanisms precisely linking epitranscriptomic alterations to disease
pathogenesis and progression.
- Designing small molecule or CRISPR-based epitranscriptomic modulators precisely
targeting modifier enzymes.
- Applying targeted RNA modification patterning or temporal control of their dynamic
regulation.
- Synthesizing minimal genomes with non-natural modification incorporation capabilities.
- Combining modifications, alternative polyadenylation, editing in synthetic genetic circuits
with emergent behaviors.
- Characterizing intergenerational epitranscriptomic inheritance and non-Mendelian
transgenerational effects.
Progress depends upon accessible public databases, open science practices transparently
sharing resources unlocking complex regulatory mechanisms central to molecular, cellular
and system-wide understanding. Overall, epitranscriptomics represents a burgeoning ‘third
layer’ of regulatory complexity connecting gene expression control to environmental sensing,
development and programmed cellular states through nuanced combinatorial RNA post-
transcriptional programs.
