1
|
Ahi EP, Singh P. Emerging Orchestrator of Ecological Adaptation: m 6A Regulation of Post-Transcriptional Mechanisms. Mol Ecol 2024:e17545. [PMID: 39367666 DOI: 10.1111/mec.17545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 09/01/2024] [Accepted: 09/19/2024] [Indexed: 10/06/2024]
Abstract
Genetic mechanisms have been at the forefront of our exploration into the substrate of adaptive evolution and phenotypic diversification. However, genetic variation only accounts for a fraction of phenotypic variation. In the last decade, the significance of RNA modification mechanisms has become more apparent in the context of organismal adaptation to rapidly changing environments. RNA m6A methylation, the most abundant form of RNA modification, is emerging as a potentially significant player in various biological processes. Despite its fundamental function to regulate other major post-transcriptional mechanisms such as microRNA and alternative splicing, its role in ecology and evolution has been understudied. This review highlights the potential importance of m6A RNA methylation in ecological adaptation, emphasising the need for further research, especially in natural systems. We focus on how m6A not only affects mRNA fate but also influences miRNA-mediated gene regulation and alternative splicing, potentially contributing to organismal adaptation. The aim of this review is to synthesise key background information to enhance our understanding of m6A mechanisms driving species survival in dynamic environments and motivate future research into the dynamics of adaptive RNA methylation.
Collapse
Affiliation(s)
- Ehsan Pashay Ahi
- Organismal and Evolutionary Biology Research Programme, University of Helsinki, Helsinki, Finland
| | - Pooja Singh
- Institute of Ecology and Evolution, University of Bern, Bern, Switzerland
- Swiss Federal Institute of Aquatic Science and Technology (EAWAG), Kastanienbaum, Switzerland
| |
Collapse
|
2
|
Bénitière F, Duret L, Necsulea A. GTDrift: a resource for exploring the interplay between genetic drift, genomic and transcriptomic characteristics in eukaryotes. NAR Genom Bioinform 2024; 6:lqae064. [PMID: 38867915 PMCID: PMC11167491 DOI: 10.1093/nargab/lqae064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 04/22/2024] [Accepted: 05/27/2024] [Indexed: 06/14/2024] Open
Abstract
We present GTDrift, a comprehensive data resource that enables explorations of genomic and transcriptomic characteristics alongside proxies of the intensity of genetic drift in individual species. This resource encompasses data for 1506 eukaryotic species, including 1413 animals and 93 green plants, and is organized in three components. The first two components contain approximations of the effective population size, which serve as indicators of the extent of random genetic drift within each species. In the first component, we meticulously investigated public databases to assemble data on life history traits such as longevity, adult body length and body mass for a set of 979 species. The second component includes estimations of the ratio between the rate of non-synonymous substitutions and the rate of synonymous substitutions (dN/dS) in protein-coding sequences for 1324 species. This ratio provides an estimate of the efficiency of natural selection in purging deleterious substitutions. Additionally, we present polymorphism-derived N e estimates for 66 species. The third component encompasses various genomic and transcriptomic characteristics. With this component, we aim to facilitate comparative transcriptomics analyses across species, by providing easy-to-use processed data for more than 16 000 RNA-seq samples across 491 species. These data include intron-centered alternative splicing frequencies, gene expression levels and sequencing depth statistics for each species, obtained with a homogeneous analysis protocol. To enable cross-species comparisons, we provide orthology predictions for conserved single-copy genes based on BUSCO gene sets. To illustrate the possible uses of this database, we identify the most frequently used introns for each gene and we assess how the sequencing depth available for each species affects our power to identify major and minor splice variants.
Collapse
Affiliation(s)
- Florian Bénitière
- Laboratoire de Biométrie et Biologie Évolutive, Université Lyon 1, UMR CNRS 5558, Villeurbanne, France
- Laboratoire d’Écologie des Hydrosystèmes Naturels et Anthropisés, Université Lyon 1, UMR CNRS 5023, Villeurbanne, France
| | - Laurent Duret
- Laboratoire de Biométrie et Biologie Évolutive, Université Lyon 1, UMR CNRS 5558, Villeurbanne, France
| | - Anamaria Necsulea
- Laboratoire de Biométrie et Biologie Évolutive, Université Lyon 1, UMR CNRS 5558, Villeurbanne, France
| |
Collapse
|
3
|
Bénitière F, Necsulea A, Duret L. Random genetic drift sets an upper limit on mRNA splicing accuracy in metazoans. eLife 2024; 13:RP93629. [PMID: 38470242 DOI: 10.7554/elife.93629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/13/2024] Open
Abstract
Most eukaryotic genes undergo alternative splicing (AS), but the overall functional significance of this process remains a controversial issue. It has been noticed that the complexity of organisms (assayed by the number of distinct cell types) correlates positively with their genome-wide AS rate. This has been interpreted as evidence that AS plays an important role in adaptive evolution by increasing the functional repertoires of genomes. However, this observation also fits with a totally opposite interpretation: given that 'complex' organisms tend to have small effective population sizes (Ne), they are expected to be more affected by genetic drift, and hence more prone to accumulate deleterious mutations that decrease splicing accuracy. Thus, according to this 'drift barrier' theory, the elevated AS rate in complex organisms might simply result from a higher splicing error rate. To test this hypothesis, we analyzed 3496 transcriptome sequencing samples to quantify AS in 53 metazoan species spanning a wide range of Ne values. Our results show a negative correlation between Ne proxies and the genome-wide AS rates among species, consistent with the drift barrier hypothesis. This pattern is dominated by low abundance isoforms, which represent the vast majority of the splice variant repertoire. We show that these low abundance isoforms are depleted in functional AS events, and most likely correspond to errors. Conversely, the AS rate of abundant isoforms, which are relatively enriched in functional AS events, tends to be lower in more complex species. All these observations are consistent with the hypothesis that variation in AS rates across metazoans reflects the limits set by drift on the capacity of selection to prevent gene expression errors.
Collapse
Affiliation(s)
- Florian Bénitière
- Laboratoire de Biometrie et Biologie Evolutive, CNRS, Universite Lyon 1, Villeurbanne, France
| | - Anamaria Necsulea
- Laboratoire de Biometrie et Biologie Evolutive, CNRS, Universite Lyon 1, Villeurbanne, France
| | - Laurent Duret
- Laboratoire de Biometrie et Biologie Evolutive, CNRS, Universite Lyon 1, Villeurbanne, France
| |
Collapse
|
4
|
Shachar R, Dierks D, Garcia-Campos MA, Uzonyi A, Toth U, Rossmanith W, Schwartz S. Dissecting the sequence and structural determinants guiding m6A deposition and evolution via inter- and intra-species hybrids. Genome Biol 2024; 25:48. [PMID: 38360609 PMCID: PMC10870504 DOI: 10.1186/s13059-024-03182-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 02/04/2024] [Indexed: 02/17/2024] Open
Abstract
BACKGROUND N6-methyladenosine (m6A) is the most abundant mRNA modification, and controls mRNA stability. m6A distribution varies considerably between and within species. Yet, it is unclear to what extent this variability is driven by changes in genetic sequences ('cis') or cellular environments ('trans') and via which mechanisms. RESULTS Here we dissect the determinants governing RNA methylation via interspecies and intraspecies hybrids in yeast and mammalian systems, coupled with massively parallel reporter assays and m6A-QTL reanalysis. We find that m6A evolution and variability is driven primarily in 'cis', via two mechanisms: (1) variations altering m6A consensus motifs, and (2) variation impacting mRNA secondary structure. We establish that mutations impacting RNA structure - even when distant from an m6A consensus motif - causally dictate methylation propensity. Finally, we demonstrate that allele-specific differences in m6A levels lead to allele-specific changes in gene expression. CONCLUSIONS Our findings define the determinants governing m6A evolution and diversity and characterize the consequences thereof on gene expression regulation.
Collapse
Affiliation(s)
- Ran Shachar
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 7630031, Israel
| | - David Dierks
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 7630031, Israel
| | | | - Anna Uzonyi
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 7630031, Israel
| | - Ursula Toth
- Center for Anatomy & Cell Biology, Medical University of Vienna, Vienna, 1090, Austria
| | - Walter Rossmanith
- Center for Anatomy & Cell Biology, Medical University of Vienna, Vienna, 1090, Austria
| | - Schraga Schwartz
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 7630031, Israel.
| |
Collapse
|
5
|
Lewin LE, Daniels KG, Hurst LD. Genes for highly abundant proteins in Escherichia coli avoid 5' codons that promote ribosomal initiation. PLoS Comput Biol 2023; 19:e1011581. [PMID: 37878567 PMCID: PMC10599525 DOI: 10.1371/journal.pcbi.1011581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 10/09/2023] [Indexed: 10/27/2023] Open
Abstract
In many species highly expressed genes (HEGs) over-employ the synonymous codons that match the more abundant iso-acceptor tRNAs. Bacterial transgene codon randomization experiments report, however, that enrichment with such "translationally optimal" codons has little to no effect on the resultant protein level. By contrast, consistent with the view that ribosomal initiation is rate limiting, synonymous codon usage following the 5' ATG greatly influences protein levels, at least in part by modifying RNA stability. For the design of bacterial transgenes, for simple codon based in silico inference of protein levels and for understanding selection on synonymous mutations, it would be valuable to computationally determine initiation optimality (IO) scores for codons for any given species. One attractive approach is to characterize the 5' codon enrichment of HEGs compared with the most lowly expressed genes, just as translational optimality scores of codons have been similarly defined employing the full gene body. Here we determine the viability of this approach employing a unique opportunity: for Escherichia coli there is both the most extensive protein abundance data for native genes and a unique large-scale transgene codon randomization experiment enabling objective definition of the 5' codons that cause, rather than just correlate with, high protein abundance (that we equate with initiation optimality, broadly defined). Surprisingly, the 5' ends of native genes that specify highly abundant proteins avoid such initiation optimal codons. We find that this is probably owing to conflicting selection pressures particular to native HEGs, including selection favouring low initiation rates, this potentially enabling high efficiency of ribosomal usage and low noise. While the classical HEG enrichment approach does not work, rendering simple prediction of native protein abundance from 5' codon content futile, we report evidence that initiation optimality scores derived from the transgene experiment may hold relevance for in silico transgene design for a broad spectrum of bacteria.
Collapse
Affiliation(s)
- Loveday E. Lewin
- The Milner Centre for Evolution, Department of Life Sciences, University of Bath, Bath, United Kingdom
| | - Kate G. Daniels
- The Milner Centre for Evolution, Department of Life Sciences, University of Bath, Bath, United Kingdom
| | - Laurence D. Hurst
- The Milner Centre for Evolution, Department of Life Sciences, University of Bath, Bath, United Kingdom
| |
Collapse
|
6
|
Zhang J, Xu C. Gene product diversity: adaptive or not? Trends Genet 2022; 38:1112-1122. [PMID: 35641344 PMCID: PMC9560964 DOI: 10.1016/j.tig.2022.05.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 04/30/2022] [Accepted: 05/03/2022] [Indexed: 01/24/2023]
Abstract
One gene does not equal one RNA or protein. The genomic revolution has revealed numerous different RNA and protein molecules that can be produced from one gene, such as circular RNAs generated by back-splicing, proteins with residues mismatching the genomic encoding because of RNA editing, and proteins extended in the C terminus via stop codon readthrough in translation. Are these diverse products results of exquisite gene regulations or imprecise biological processes? While there are cases where the gene product diversity appears beneficial, genome-scale patterns suggest that much of this diversity arises from nonadaptive, molecular errors. This finding has important implications for studying the functions of diverse gene products and for understanding the fundamental properties and evolution of cellular life.
Collapse
Affiliation(s)
- Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA.
| | - Chuan Xu
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Shanghai Jiao Tong University, Shanghai 200240, China
| |
Collapse
|
7
|
Lv J, Song Q, Bai K, Han J, Yu H, Li K, Zhuang J, Yang X, Yang H, Lu Q. N6-methyladenosine-related single-nucleotide polymorphism analyses identify oncogene RNFT2 in bladder cancer. Cancer Cell Int 2022; 22:301. [PMID: 36199110 PMCID: PMC9535860 DOI: 10.1186/s12935-022-02701-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 09/03/2022] [Indexed: 12/24/2022] Open
Abstract
Background Single-nucleotide polymorphisms (SNPs) in N6-methyladenosine (m6A) related genetic locus play significant roles in tumorigenesis and development. The expression level of many oncogenes and tumour suppressor genes changed because of m6A-associated SNPs. In addition, the relationship between m6A-SNP and bladder cancer (BCa) has not been well studied. Methods We screened m6A-SNPs in BCa by combining m6A-SNPs data and GWAS-SNPs data. Expression quantitative trait loci (eQTL) and differential expression gene (DEGs) analyses were performed. In ring finger protein, transmembrane 2 (RNFT2), rs3088107 (C > G) was found to have significant eQTL signals and make RNFT2 gene differentially-regulated mostly in BCa. We validated the expression level of RNFT2 in 32 pairs of BCa tissues and eight BCa cell lines by quantitative real-time PCR (qRT-PCR). Functional assays were performed to investigate the role of rs3088107 and RNFT2 in BCa in vitro. Results We identified 673 m6A-SNPs, which were associated with BCa. Of these m6A-SNPs, 221 showed eQTL signals, amongst which, rs3088107 in RNFT2 showed significant eQTL signals. Results of bioinformatic analyses showed that 11 genes with m6A-SNPs had a differential expression level in BCa. RNFT2 was predicted to be significantly up-regulated in BCa. The qRT-PCR results validated that RNFT2 was highly expressed in our own BCa tissues and cell lines. High expression of RNFT2 also indicated a worse overall survival. We also revealed that rs3088107 (C > G) could inhibit the expression and m6A modification of RNFT2 by qRT-PCR, western-blot and m6A-RIP assays. Moreover, the results of functional assays indicated that RNFT2 promoted BCa cell proliferation and migration. Conclusion This research found that m6A-SNPs were associated with oncogene RNFT2 in BCa. Furthermore, m6A-SNPs showed great application potential as a new BCa diagnostic biomarker and prognostic indicator. Supplementary Information The online version contains supplementary material available at 10.1186/s12935-022-02701-z.
Collapse
Affiliation(s)
- Jiancheng Lv
- Department of Urology, The First Affiliated Hospital of Nanjing Medical University, No. 300 Guangzhou Road, Nanjing, 210029, China
| | - Qiang Song
- Department of Urology, The First Affiliated Hospital of Nanjing Medical University, No. 300 Guangzhou Road, Nanjing, 210029, China
| | - Kexin Bai
- Department of Urology, The First Affiliated Hospital of Nanjing Medical University, No. 300 Guangzhou Road, Nanjing, 210029, China
| | - Jie Han
- Department of Urology, The First Affiliated Hospital of Nanjing Medical University, No. 300 Guangzhou Road, Nanjing, 210029, China
| | - Hao Yu
- Department of Urology, The First Affiliated Hospital of Nanjing Medical University, No. 300 Guangzhou Road, Nanjing, 210029, China
| | - Kai Li
- Department of Urology, The First Affiliated Hospital of Nanjing Medical University, No. 300 Guangzhou Road, Nanjing, 210029, China
| | - Juntao Zhuang
- Department of Urology, The First Affiliated Hospital of Nanjing Medical University, No. 300 Guangzhou Road, Nanjing, 210029, China
| | - Xiao Yang
- Department of Urology, The First Affiliated Hospital of Nanjing Medical University, No. 300 Guangzhou Road, Nanjing, 210029, China.
| | - Haiwei Yang
- Department of Urology, The First Affiliated Hospital of Nanjing Medical University, No. 300 Guangzhou Road, Nanjing, 210029, China.
| | - Qiang Lu
- Department of Urology, The First Affiliated Hospital of Nanjing Medical University, No. 300 Guangzhou Road, Nanjing, 210029, China.
| |
Collapse
|
8
|
Sikorski V, Vento A, Kankuri E. Emerging roles of the RNA modifications N6-methyladenosine and adenosine-to-inosine in cardiovascular diseases. MOLECULAR THERAPY. NUCLEIC ACIDS 2022; 29:426-461. [PMID: 35991314 PMCID: PMC9366019 DOI: 10.1016/j.omtn.2022.07.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Cardiovascular diseases lead the mortality and morbidity disease metrics worldwide. A multitude of chemical base modifications in ribonucleic acids (RNAs) have been linked with key events of cardiovascular diseases and metabolic disorders. Named either RNA epigenetics or epitranscriptomics, the post-transcriptional RNA modifications, their regulatory pathways, components, and downstream effects substantially contribute to the ways our genetic code is interpreted. Here we review the accumulated discoveries to date regarding the roles of the two most common epitranscriptomic modifications, N6-methyl-adenosine (m6A) and adenosine-to-inosine (A-to-I) editing, in cardiovascular disease.
Collapse
Affiliation(s)
- Vilbert Sikorski
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, 00014 Helsinki, Finland
| | - Antti Vento
- Heart and Lung Center, Helsinki University Hospital, 00029 Helsinki, Finland
| | - Esko Kankuri
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, 00014 Helsinki, Finland
| | - IHD-EPITRAN Consortium
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, 00014 Helsinki, Finland
- Heart and Lung Center, Helsinki University Hospital, 00029 Helsinki, Finland
| |
Collapse
|
9
|
Role of Epitranscriptomic and Epigenetic Modifications during the Lytic and Latent Phases of Herpesvirus Infections. Microorganisms 2022; 10:microorganisms10091754. [PMID: 36144356 PMCID: PMC9503318 DOI: 10.3390/microorganisms10091754] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 08/27/2022] [Accepted: 08/27/2022] [Indexed: 11/24/2022] Open
Abstract
Herpesviruses are double-stranded DNA viruses occurring at a high prevalence in the human population and are responsible for a wide array of clinical manifestations and diseases, from mild to severe. These viruses are classified in three subfamilies (Alpha-, Beta- and Gammaherpesvirinae), with eight members currently known to infect humans. Importantly, all herpesviruses can establish lifelong latent infections with symptomatic or asymptomatic lytic reactivations. Accumulating evidence suggest that chemical modifications of viral RNA and DNA during the lytic and latent phases of the infections caused by these viruses, are likely to play relevant roles in key aspects of the life cycle of these viruses by modulating and regulating their replication, establishment of latency and evasion of the host antiviral response. Here, we review and discuss current evidence regarding epitranscriptomic and epigenetic modifications of herpesviruses and how these can influence their life cycles. While epitranscriptomic modifications such as m6A are the most studied to date and relate to positive effects over the replication of herpesviruses, epigenetic modifications of the viral genome are generally associated with defense mechanisms of the host cells to suppress viral gene transcription. However, herpesviruses can modulate these modifications to their own benefit to persist in the host, undergo latency and sporadically reactivate.
Collapse
|
10
|
Zhou S, Sun Y, Xing Y, Wang Z, Wan S, Yao X, Hua Q, Meng X, Cheng J, Zhong M, Lv K, Kong X. Exenatide ameliorates hydrogen peroxide-induced pancreatic β-cell apoptosis through regulation of METTL3-mediated m 6A methylation. Eur J Pharmacol 2022; 924:174960. [PMID: 35436474 DOI: 10.1016/j.ejphar.2022.174960] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 04/09/2022] [Accepted: 04/12/2022] [Indexed: 01/05/2023]
Abstract
Exenatide, a glucagon-like peptide-1 (GLP-1) receptor agonist, is a commonly used hypoglycemic agent in clinical practice; it inhibits reactive oxygen species-induced pancreatic β-cell apoptosis. N6-methyladenosine (m6A) is produced by the methylation of RNA N6 residues and has recently been shown to play a crucial role in the regulation of islet β-cell growth and development. However, the involvement of m6A methylation in the β-cell protective effects of exenatide has not been clarified. In this study, the m6A-methylated RNA content and methyltransferase-like 3 (METTL3) expression levels in NIT-1 cells and primary mouse islets were found to significantly decrease following treatment with hydrogen peroxide (H2O2). Treatment with exenatide induced an increase in m6A content and METTL3 expression in the H2O2-treated NIT-1 cells and islets. Moreover, METTL3 silencing resulted in NIT-1 cell apoptosis under normal culture conditions. METTL3 upregulation significantly ameliorated H2O2-induced apoptosis in NIT-1 cells and primary islets. Furthermore, the anti-apoptotic effects of exenatide were obviously reversed by METTL3 knockdown. In conclusion, these findings suggest that exenatide elicits its anti-apoptotic effects in pancreatic β-cells by promoting m6A methylation through the upregulation METTL3 expression.
Collapse
Affiliation(s)
- Simin Zhou
- Department of Endocrinology, The First Affiliated Hospital of Wannan Medical College, Yijishan Hospital, Wuhu, 241001, China; Key Laboratory of Non-coding RNA Transformation Research of Anhui Higher Education Institution, Wannan Medical College, Wuhu, 241002, China
| | - Yue Sun
- Department of Endocrinology, The First Affiliated Hospital of Wannan Medical College, Yijishan Hospital, Wuhu, 241001, China; Key Laboratory of Non-coding RNA Transformation Research of Anhui Higher Education Institution, Wannan Medical College, Wuhu, 241002, China
| | - Yujie Xing
- Department of Endocrinology, The First Affiliated Hospital of Wannan Medical College, Yijishan Hospital, Wuhu, 241001, China; Key Laboratory of Non-coding RNA Transformation Research of Anhui Higher Education Institution, Wannan Medical College, Wuhu, 241002, China
| | - Zhi Wang
- Key Laboratory of Non-coding RNA Transformation Research of Anhui Higher Education Institution, Wannan Medical College, Wuhu, 241002, China; Department of Cardiology, The First Affiliated Hospital of Wannan Medical College, Yijishan Hospital, Wuhu, 241001, China
| | - Shujun Wan
- Key Laboratory of Non-coding RNA Transformation Research of Anhui Higher Education Institution, Wannan Medical College, Wuhu, 241002, China; Central Laboratory of Yijishan Hospital, Wuhu, 241001, China
| | - Xinming Yao
- Department of Endocrinology, The First Affiliated Hospital of Wannan Medical College, Yijishan Hospital, Wuhu, 241001, China
| | - Qiang Hua
- Department of Endocrinology, The First Affiliated Hospital of Wannan Medical College, Yijishan Hospital, Wuhu, 241001, China
| | - Xiangjian Meng
- Department of Endocrinology, The First Affiliated Hospital of Wannan Medical College, Yijishan Hospital, Wuhu, 241001, China
| | - Jinhan Cheng
- Department of Endocrinology, The First Affiliated Hospital of Wannan Medical College, Yijishan Hospital, Wuhu, 241001, China
| | - Min Zhong
- Key Laboratory of Non-coding RNA Transformation Research of Anhui Higher Education Institution, Wannan Medical College, Wuhu, 241002, China; Central Laboratory of Yijishan Hospital, Wuhu, 241001, China; Clinical Research Center for Critical Respiratory Medicine of Anhui Province, Wannan Medical College, Wuhu, 241002, China
| | - Kun Lv
- Key Laboratory of Non-coding RNA Transformation Research of Anhui Higher Education Institution, Wannan Medical College, Wuhu, 241002, China; Central Laboratory of Yijishan Hospital, Wuhu, 241001, China; Clinical Research Center for Critical Respiratory Medicine of Anhui Province, Wannan Medical College, Wuhu, 241002, China.
| | - Xiang Kong
- Department of Endocrinology, The First Affiliated Hospital of Wannan Medical College, Yijishan Hospital, Wuhu, 241001, China; Key Laboratory of Non-coding RNA Transformation Research of Anhui Higher Education Institution, Wannan Medical College, Wuhu, 241002, China; Central Laboratory of Yijishan Hospital, Wuhu, 241001, China; Clinical Research Center for Critical Respiratory Medicine of Anhui Province, Wannan Medical College, Wuhu, 241002, China.
| |
Collapse
|
11
|
Chen J, Lu T, Zhong F, Lv Q, Fang M, Tu Z, Ji Y, Li J, Gong X. A Signature of N 6-methyladenosine Regulator-Related Genes Predicts Prognoses and Immune Responses for Head and Neck Squamous Cell Carcinoma. Front Immunol 2022; 13:809872. [PMID: 35185897 PMCID: PMC8851317 DOI: 10.3389/fimmu.2022.809872] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 01/14/2022] [Indexed: 01/22/2023] Open
Abstract
This study aimed to construct a signature of N6-methyladenosine (m6A) regulator-related genes that could be used for the prognosis of head and neck squamous cell carcinoma (HNSCC) and to clarify the molecular and immune characteristics and benefits of immune checkpoint inhibitor (ICI) therapy using the prognostic signature to define the subgroups of HNSCC. This study showed that eighteen m6A regulators were abnormally expressed in the Cancer Genome Atlas (TCGA) HNSCC tissues compared with those in normal tissues. We constructed a signature of 12 m6A regulator-related genes using the Cox risk model, combined with the least absolute shrinkage and selection operator (Lasso) variable screening algorithm. Based on the median of the signature risk score, the patients were divided into high- and low-risk groups. The Kaplan-Meier survival analyses showed that patients with high-risk scores demonstrated poorer overall survival (OS) than those with low-risk scores based on TCGA-HNSCC data (p <0.001). The OS of high-risk patients was significantly worse than that of low-risk patients in the GSE65858 (p <0.001) and International Cancer Genome Consortium (ICGC) oral cancer cohorts (p = 0.0089). Furthermore, immune infiltration analyses showed that 8 types of immune cell infiltration showed highly significant differences between the two risk groups (p <0.001). In the Imvigor210CoreBiologies dataset of patients who received ICIs, the objective response rate (ORR) of the low-risk group (32%) was significantly higher than that of the high-risk group (13%). Additionally, patients in the high-risk group presented with a more significant adverse OS than that of the low-risk group (p = 0.00032). GSE78220 also showed that the ORR of the low-risk group (64%) was higher than that of the high-risk group (43%) and the OS of low-risk patients was better than that of high-risk patients (p = 0.0064). The constructed prognostic signature, based on m6A regulator-related genes, could be used to effectively distinguish between prognoses for HNSCC patients. The prognostic signature was found to be related to the immune cell infiltration of HNSCC; it might help predict the responses and prognoses of ICIs during treatment.
Collapse
Affiliation(s)
- Junjun Chen
- National Health Commission (NHC), Key Laboratory of Personalized Diagnosis and Treatment of Nasopharyngeal Carcinoma, Jiangxi Cancer Hospital of Nanchang University, Nanchang, China.,Department of Science and Education, Jiangxi Key Laboratory of Translational Cancer Research, Jiangxi Cancer Hospital of Nanchang University, Nanchang, China
| | - Tianzhu Lu
- National Health Commission (NHC), Key Laboratory of Personalized Diagnosis and Treatment of Nasopharyngeal Carcinoma, Jiangxi Cancer Hospital of Nanchang University, Nanchang, China.,Department of Science and Education, Jiangxi Key Laboratory of Translational Cancer Research, Jiangxi Cancer Hospital of Nanchang University, Nanchang, China.,Department of Radiation Oncology, Jiangxi Cancer Hospital of Nanchang University, Nanchang, China
| | - Fangyan Zhong
- National Health Commission (NHC), Key Laboratory of Personalized Diagnosis and Treatment of Nasopharyngeal Carcinoma, Jiangxi Cancer Hospital of Nanchang University, Nanchang, China.,Department of Radiation Oncology, Jiangxi Cancer Hospital of Nanchang University, Nanchang, China
| | - Qiaoli Lv
- National Health Commission (NHC), Key Laboratory of Personalized Diagnosis and Treatment of Nasopharyngeal Carcinoma, Jiangxi Cancer Hospital of Nanchang University, Nanchang, China.,Department of Science and Education, Jiangxi Key Laboratory of Translational Cancer Research, Jiangxi Cancer Hospital of Nanchang University, Nanchang, China
| | - Min Fang
- National Health Commission (NHC), Key Laboratory of Personalized Diagnosis and Treatment of Nasopharyngeal Carcinoma, Jiangxi Cancer Hospital of Nanchang University, Nanchang, China.,Department of Radiation Oncology, Jiangxi Cancer Hospital of Nanchang University, Nanchang, China
| | - Ziwei Tu
- National Health Commission (NHC), Key Laboratory of Personalized Diagnosis and Treatment of Nasopharyngeal Carcinoma, Jiangxi Cancer Hospital of Nanchang University, Nanchang, China.,Department of Science and Education, Jiangxi Key Laboratory of Translational Cancer Research, Jiangxi Cancer Hospital of Nanchang University, Nanchang, China.,Department of Radiation Oncology, Jiangxi Cancer Hospital of Nanchang University, Nanchang, China
| | - Yulong Ji
- National Health Commission (NHC), Key Laboratory of Personalized Diagnosis and Treatment of Nasopharyngeal Carcinoma, Jiangxi Cancer Hospital of Nanchang University, Nanchang, China.,Department of Science and Education, Jiangxi Key Laboratory of Translational Cancer Research, Jiangxi Cancer Hospital of Nanchang University, Nanchang, China
| | - Jingao Li
- National Health Commission (NHC), Key Laboratory of Personalized Diagnosis and Treatment of Nasopharyngeal Carcinoma, Jiangxi Cancer Hospital of Nanchang University, Nanchang, China.,Department of Science and Education, Jiangxi Key Laboratory of Translational Cancer Research, Jiangxi Cancer Hospital of Nanchang University, Nanchang, China.,Department of Radiation Oncology, Jiangxi Cancer Hospital of Nanchang University, Nanchang, China
| | - Xiaochang Gong
- National Health Commission (NHC), Key Laboratory of Personalized Diagnosis and Treatment of Nasopharyngeal Carcinoma, Jiangxi Cancer Hospital of Nanchang University, Nanchang, China.,Department of Science and Education, Jiangxi Key Laboratory of Translational Cancer Research, Jiangxi Cancer Hospital of Nanchang University, Nanchang, China.,Department of Radiation Oncology, Jiangxi Cancer Hospital of Nanchang University, Nanchang, China
| |
Collapse
|
12
|
Palazzo AF, Kejiou NS. Non-Darwinian Molecular Biology. Front Genet 2022; 13:831068. [PMID: 35251134 PMCID: PMC8888898 DOI: 10.3389/fgene.2022.831068] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 01/24/2022] [Indexed: 12/14/2022] Open
Abstract
With the discovery of the double helical structure of DNA, a shift occurred in how biologists investigated questions surrounding cellular processes, such as protein synthesis. Instead of viewing biological activity through the lens of chemical reactions, this new field used biological information to gain a new profound view of how biological systems work. Molecular biologists asked new types of questions that would have been inconceivable to the older generation of researchers, such as how cellular machineries convert inherited biological information into functional molecules like proteins. This new focus on biological information also gave molecular biologists a way to link their findings to concepts developed by genetics and the modern synthesis. However, by the late 1960s this all changed. Elevated rates of mutation, unsustainable genetic loads, and high levels of variation in populations, challenged Darwinian evolution, a central tenant of the modern synthesis, where adaptation was the main driver of evolutionary change. Building on these findings, Motoo Kimura advanced the neutral theory of molecular evolution, which advocates that selection in multicellular eukaryotes is weak and that most genomic changes are neutral and due to random drift. This was further elaborated by Jack King and Thomas Jukes, in their paper “Non-Darwinian Evolution”, where they pointed out that the observed changes seen in proteins and the types of polymorphisms observed in populations only become understandable when we take into account biochemistry and Kimura’s new theory. Fifty years later, most molecular biologists remain unaware of these fundamental advances. Their adaptionist viewpoint fails to explain data collected from new powerful technologies which can detect exceedingly rare biochemical events. For example, high throughput sequencing routinely detects RNA transcripts being produced from almost the entire genome yet are present less than one copy per thousand cells and appear to lack any function. Molecular biologists must now reincorporate ideas from classical biochemistry and absorb modern concepts from molecular evolution, to craft a new lens through which they can evaluate the functionality of transcriptional units, and make sense of our messy, intricate, and complicated genome.
Collapse
|
13
|
Xu C, Zhang J. Mammalian circular RNAs result largely from splicing errors. Cell Rep 2021; 36:109439. [PMID: 34320353 PMCID: PMC8365531 DOI: 10.1016/j.celrep.2021.109439] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 04/13/2021] [Accepted: 07/02/2021] [Indexed: 12/20/2022] Open
Abstract
Ubiquitous in eukaryotes, circular RNAs (circRNAs) comprise a large class of mostly non-coding RNAs produced by back-splicing. Although some circRNAs have demonstrated biochemical activities, whether most circRNAs are functional is unknown. Here, we test the hypothesis that circRNA production primarily results from splicing error and so is deleterious instead of beneficial. In support of the error hypothesis, our analysis of RNA sequencing data from 11 shared tissues of humans, macaques, and mice finds that (1) back-splicing is much rarer than linear-splicing, (2) the rate of back-splicing diminishes with the splicing amount, (3) the overall prevalence of back-splicing in a species declines with its effective population size, and (4) circRNAs are overall evolutionarily unconserved. We estimate that more than 97% of the observed circRNA production is deleterious. We identify a small number of functional circRNA candidates, and the genome-wide trend strongly suggests that circRNAs are largely non-functional products of splicing errors.
Collapse
Affiliation(s)
- Chuan Xu
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders of Ministry of Education, Shanghai Jiao Tong University, Shanghai 200240, China; Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan 48109, USA.
| |
Collapse
|
14
|
Zhao H, Jiang J, Wang M, Xuan Z. Genome-Wide Identification of m6A-Associated Single-Nucleotide Polymorphisms in Colorectal Cancer. PHARMACOGENOMICS & PERSONALIZED MEDICINE 2021; 14:887-892. [PMID: 34305406 PMCID: PMC8297552 DOI: 10.2147/pgpm.s314373] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 06/30/2021] [Indexed: 12/15/2022]
Abstract
Background N6-methyladenosine (m6A)-associated single-nucleotide polymorphisms (SNPs) play important roles in cancers, with previous research suggesting potential associations between m6A-SNPs and cancer. However, the relationship between the genetic determinants of m6A modification and colorectal cancer (CRC) remains unclear. Methods An integrative method combining raw data and summary statistics of genome-wide association studies with expression quantitative trait loci (eQTL) and differential expression data was applied to screen potential candidate CRC-associated m6A-SNPs. Results A total of 402 m6A-SNPs were identified as being associated with CRC (p < 0.001), with 98 showing eQTL signals. In particular, three genes were found to harbor CRC-associated m6A-SNPs: rs178184 in NOVA1, rs35782901 in HTR4, and rs60571683 in SLCO1B3. These genes were differentially expressed in at least one publicly available dataset (p < 0.05), with NOVA1 (p = 3.41×10-11) and HTR4 (p = 5.56×10-7) being significantly downregulated in CRC (dataset: GSE89076), and SLCO1B3 was significantly overexpressed (datasets: GSE32323 [p = 3.27×10-5], GSE21510 [p = 1.09×10-6], and GSE89076 [p = 7.63×10-6]). Conclusion This study identified three m6A-SNPs (rs178184, rs35782901, and rs60571683) that may be associated with CRC. However, the lack of analysis of primary CRC samples in order to further elucidate the underlying pathogenesis is a major limitation of this study. Future investigations are needed to validate these CRC-associated m6A-SNPs and explore the m6A-mediated pathogenic mechanism in CRC.
Collapse
Affiliation(s)
- Hongying Zhao
- Clinical Pharmacy Center, Department of Pharmacy, Zhejiang Provincial People's Hospital, Affiliated People's Hospital, Hangzhou Medical College, Hangzhou, Zhejiang, People's Republic of China
| | - Jinying Jiang
- Clinical Pharmacy Center, Department of Pharmacy, Zhejiang Provincial People's Hospital, Affiliated People's Hospital, Hangzhou Medical College, Hangzhou, Zhejiang, People's Republic of China
| | - Mingshan Wang
- Departments of Infection Diseases, Zhejiang Provincial People's Hospital, Affiliated People's Hospital, Hangzhou Medical College, Hangzhou, Zhejiang, People's Republic of China
| | - Zixue Xuan
- Clinical Pharmacy Center, Department of Pharmacy, Zhejiang Provincial People's Hospital, Affiliated People's Hospital, Hangzhou Medical College, Hangzhou, Zhejiang, People's Republic of China.,Key Laboratory of Endocrine Gland Diseases of Zhejiang Province, Zhejiang Provincial People's Hospital, Affiliated People's Hospital, Hangzhou Medical College, Hangzhou, Zhejiang, People's Republic of China
| |
Collapse
|
15
|
Ho AT, Hurst LD. Effective Population Size Predicts Local Rates but Not Local Mitigation of Read-through Errors. Mol Biol Evol 2021; 38:244-262. [PMID: 32797190 PMCID: PMC7783166 DOI: 10.1093/molbev/msaa210] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
In correctly predicting that selection efficiency is positively correlated with the effective population size (Ne), the nearly neutral theory provides a coherent understanding of between-species variation in numerous genomic parameters, including heritable error (germline mutation) rates. Does the same theory also explain variation in phenotypic error rates and in abundance of error mitigation mechanisms? Translational read-through provides a model to investigate both issues as it is common, mostly nonadaptive, and has good proxy for rate (TAA being the least leaky stop codon) and potential error mitigation via "fail-safe" 3' additional stop codons (ASCs). Prior theory of translational read-through has suggested that when population sizes are high, weak selection for local mitigation can be effective thus predicting a positive correlation between ASC enrichment and Ne. Contra to prediction, we find that ASC enrichment is not correlated with Ne. ASC enrichment, although highly phylogenetically patchy, is, however, more common both in unicellular species and in genes expressed in unicellular modes in multicellular species. By contrast, Ne does positively correlate with TAA enrichment. These results imply that local phenotypic error rates, not local mitigation rates, are consistent with a drift barrier/nearly neutral model.
Collapse
Affiliation(s)
- Alexander T Ho
- Milner Centre for Evolution, University of Bath, Bath, United Kingdom
- Corresponding author: E-mail:
| | - Laurence D Hurst
- Milner Centre for Evolution, University of Bath, Bath, United Kingdom
| |
Collapse
|
16
|
Tan L, Cheng W, Liu F, Wang DO, Wu L, Cao N, Wang J. Positive natural selection of N6-methyladenosine on the RNAs of processed pseudogenes. Genome Biol 2021; 22:180. [PMID: 34120636 PMCID: PMC8201931 DOI: 10.1186/s13059-021-02402-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 06/04/2021] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Canonical nonsense-mediated decay (NMD) is an important splicing-dependent process for mRNA surveillance in mammals. However, processed pseudogenes are not able to trigger NMD due to their lack of introns. It is largely unknown whether they have evolved other surveillance mechanisms. RESULTS Here, we find that the RNAs of pseudogenes, especially processed pseudogenes, have dramatically higher m6A levels than their cognate protein-coding genes, associated with de novo m6A peaks and motifs in human cells. Furthermore, pseudogenes have rapidly accumulated m6A motifs during evolution. The m6A sites of pseudogenes are evolutionarily younger than neutral sites and their m6A levels are increasing, supporting the idea that m6A on the RNAs of pseudogenes is under positive selection. We then find that the m6A RNA modification of processed, rather than unprocessed, pseudogenes promotes cytosolic RNA degradation and attenuates interference with the RNAs of their cognate protein-coding genes. We experimentally validate the m6A RNA modification of two processed pseudogenes, DSTNP2 and NAP1L4P1, which promotes the RNA degradation of both pseudogenes and their cognate protein-coding genes DSTN and NAP1L4. In addition, the m6A of DSTNP2 regulation of DSTN is partially dependent on the miRNA miR-362-5p. CONCLUSIONS Our discovery reveals a novel evolutionary role of m6A RNA modification in cleaning up the unnecessary processed pseudogene transcripts to attenuate their interference with the regulatory network of protein-coding genes.
Collapse
Affiliation(s)
- Liqiang Tan
- Department of Medical Informatics, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
- Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080, China
| | - Weisheng Cheng
- Department of Medical Informatics, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
- Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080, China
| | - Fang Liu
- Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080, China
| | - Dan Ohtan Wang
- Center for Biosystems Dynamics Research, RIKEN, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo, 650-0047, Japan
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, 110016, China
| | - Linwei Wu
- Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080, China
| | - Nan Cao
- Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080, China
| | - Jinkai Wang
- Department of Medical Informatics, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China.
- Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080, China.
- RNA Biomedical Institute, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, 510120, China.
| |
Collapse
|
17
|
Song B, Chen K, Tang Y, Wei Z, Su J, de Magalhães JP, Rigden DJ, Meng J. ConsRM: collection and large-scale prediction of the evolutionarily conserved RNA methylation sites, with implications for the functional epitranscriptome. Brief Bioinform 2021; 22:6276017. [PMID: 33993206 DOI: 10.1093/bib/bbab088] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 02/04/2021] [Accepted: 02/24/2021] [Indexed: 12/15/2022] Open
Abstract
Motivation N6-methyladenosine (m6A) is the most prevalent RNA modification on mRNAs and lncRNAs. Evidence increasingly demonstrates its crucial importance in essential molecular mechanisms and various diseases. With recent advances in sequencing techniques, tens of thousands of m6A sites are identified in a typical high-throughput experiment, posing a key challenge to distinguish the functional m6A sites from the remaining 'passenger' (or 'silent') sites. Results: We performed a comparative conservation analysis of the human and mouse m6A epitranscriptomes at single site resolution. A novel scoring framework, ConsRM, was devised to quantitatively measure the degree of conservation of individual m6A sites. ConsRM integrates multiple information sources and a positive-unlabeled learning framework, which integrated genomic and sequence features to trace subtle hints of epitranscriptome layer conservation. With a series validation experiments in mouse, fly and zebrafish, we showed that ConsRM outperformed well-adopted conservation scores (phastCons and phyloP) in distinguishing the conserved and unconserved m6A sites. Additionally, the m6A sites with a higher ConsRM score are more likely to be functionally important. An online database was developed containing the conservation metrics of 177 998 distinct human m6A sites to support conservation analysis and functional prioritization of individual m6A sites. And it is freely accessible at: https://www.xjtlu.edu.cn/biologicalsciences/con.
Collapse
Affiliation(s)
- Bowen Song
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, L7 8TX, Liverpool, United Kingdom
| | - Kunqi Chen
- Key Laboratory of Ministry of Education of Gastrointestinal Cancer, School of Basic Medical Science, Fujian Medical University, Fuzhou, China
| | - Yujiao Tang
- Xi'an Jiaotong-Liverpool University, L7 8TX, Liverpool, United Kingdom
| | - Zhen Wei
- Department of Biological Science, Xi'an Jiaotong-Liverpool University, L7 8TX, Liverpool, United Kingdom
| | - Jionglong Su
- Department of Mathematical Sciences, Xi'an Jiaotong-Liverpool University, L7 8TX, Liverpool, United Kingdom
| | - João Pedro de Magalhães
- Institute of Ageing & Chronic Disease, University of Liverpool, L7 8TX, Liverpool, United Kingdom
| | - Daniel J Rigden
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, L7 8TX, Liverpool, United Kingdom
| | - Jia Meng
- Department of Biological Sciences, Xi'an Jiaotong-Liverpool University, L7 8TX, Liverpool, United Kingdom
| |
Collapse
|
18
|
Jungreis I, Sealfon R, Kellis M. SARS-CoV-2 gene content and COVID-19 mutation impact by comparing 44 Sarbecovirus genomes. Nat Commun 2021; 12:2642. [PMID: 33976134 PMCID: PMC8113528 DOI: 10.1038/s41467-021-22905-7] [Citation(s) in RCA: 110] [Impact Index Per Article: 36.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 03/28/2021] [Indexed: 02/03/2023] Open
Abstract
Despite its clinical importance, the SARS-CoV-2 gene set remains unresolved, hindering dissection of COVID-19 biology. We use comparative genomics to provide a high-confidence protein-coding gene set, characterize evolutionary constraint, and prioritize functional mutations. We select 44 Sarbecovirus genomes at ideally-suited evolutionary distances, and quantify protein-coding evolutionary signatures and overlapping constraint. We find strong protein-coding signatures for ORFs 3a, 6, 7a, 7b, 8, 9b, and a novel alternate-frame gene, ORF3c, whereas ORFs 2b, 3d/3d-2, 3b, 9c, and 10 lack protein-coding signatures or convincing experimental evidence of protein-coding function. Furthermore, we show no other conserved protein-coding genes remain to be discovered. Mutation analysis suggests ORF8 contributes to within-individual fitness but not person-to-person transmission. Cross-strain and within-strain evolutionary pressures agree, except for fewer-than-expected within-strain mutations in nsp3 and S1, and more-than-expected in nucleocapsid, which shows a cluster of mutations in a predicted B-cell epitope, suggesting immune-avoidance selection. Evolutionary histories of residues disrupted by spike-protein substitutions D614G, N501Y, E484K, and K417N/T provide clues about their biology, and we catalog likely-functional co-inherited mutations. Previously reported RNA-modification sites show no enrichment for conservation. Here we report a high-confidence gene set and evolutionary-history annotations providing valuable resources and insights on SARS-CoV-2 biology, mutations, and evolution.
Collapse
Affiliation(s)
- Irwin Jungreis
- MIT Computer Science and Artificial Intelligence Laboratory, Cambridge, MA, USA.
- Broad Institute of MIT and Harvard, Cambridge, MA, USA.
| | - Rachel Sealfon
- Center for Computational Biology, Flatiron Institute, Simons Foundation, New York, NY, USA
| | - Manolis Kellis
- MIT Computer Science and Artificial Intelligence Laboratory, Cambridge, MA, USA.
- Broad Institute of MIT and Harvard, Cambridge, MA, USA.
| |
Collapse
|
19
|
Kosinski LJ, Masel J. Readthrough Errors Purge Deleterious Cryptic Sequences, Facilitating the Birth of Coding Sequences. Mol Biol Evol 2021; 37:1761-1774. [PMID: 32101291 DOI: 10.1093/molbev/msaa046] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
De novo protein-coding innovations sometimes emerge from ancestrally noncoding DNA, despite the expectation that translating random sequences is overwhelmingly likely to be deleterious. The "preadapting selection" hypothesis claims that emergence is facilitated by prior, low-level translation of noncoding sequences via molecular errors. It predicts that selection on polypeptides translated only in error is strong enough to matter and is strongest when erroneous expression is high. To test this hypothesis, we examined noncoding sequences located downstream of stop codons (i.e., those potentially translated by readthrough errors) in Saccharomyces cerevisiae genes. We identified a class of "fragile" proteins under strong selection to reduce readthrough, which are unlikely substrates for co-option. Among the remainder, sequences showing evidence of readthrough translation, as assessed by ribosome profiling, encoded C-terminal extensions with higher intrinsic structural disorder, supporting the preadapting selection hypothesis. The cryptic sequences beyond the stop codon, rather than spillover effects from the regular C-termini, are primarily responsible for the higher disorder. Results are robust to controlling for the fact that stronger selection also reduces the length of C-terminal extensions. These findings indicate that selection acts on 3' UTRs in Saccharomyces cerevisiae to purge potentially deleterious variants of cryptic polypeptides, acting more strongly in genes that experience more readthrough errors.
Collapse
Affiliation(s)
- Luke J Kosinski
- Molecular and Cellular Biology, University of Arizona, Tucson, AZ
| | - Joanna Masel
- Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ
| |
Collapse
|
20
|
Xu C, Zhang J. Mammalian Alternative Translation Initiation Is Mostly Nonadaptive. Mol Biol Evol 2021; 37:2015-2028. [PMID: 32145028 DOI: 10.1093/molbev/msaa063] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Alternative translation initiation (ATLI) refers to the existence of multiple translation initiation sites per gene and is a widespread phenomenon in eukaryotes. ATLI is commonly assumed to be advantageous through creating proteome diversity or regulating protein synthesis. We here propose an alternative hypothesis that ATLI arises primarily from nonadaptive initiation errors presumably due to the limited ability of ribosomes to distinguish sequence motifs truly signaling translation initiation from similar sequences. Our hypothesis, but not the adaptive hypothesis, predicts a series of global patterns of ATLI, all of which are confirmed at the genomic scale by quantitative translation initiation sequencing in multiple human and mouse cell lines and tissues. Similarly, although many codons differing from AUG by one nucleotide can serve as start codons, our analysis suggests that using non-AUG start codons is mostly disadvantageous. These and other findings strongly suggest that ATLI predominantly results from molecular error, requiring a major revision of our understanding of the precision and regulation of translation initiation.
Collapse
Affiliation(s)
- Chuan Xu
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI
| |
Collapse
|
21
|
Hia F, Takeuchi O. The effects of codon bias and optimality on mRNA and protein regulation. Cell Mol Life Sci 2021; 78:1909-1928. [PMID: 33128106 PMCID: PMC11072601 DOI: 10.1007/s00018-020-03685-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 10/05/2020] [Accepted: 10/12/2020] [Indexed: 12/25/2022]
Abstract
The central dogma of molecular biology entails that genetic information is transferred from nucleic acid to proteins. Notwithstanding retro-transcribing genetic elements, DNA is transcribed to RNA which in turn is translated into proteins. Recent advancements have shown that each stage is regulated to control protein abundances for a variety of essential physiological processes. In this regard, mRNA regulation is essential in fine-tuning or calibrating protein abundances. In this review, we would like to discuss one of several mRNA-intrinsic features of mRNA regulation that has been gaining traction of recent-codon bias and optimality. Specifically, we address the effects of codon bias with regard to codon optimality in several biological processes centred on translation, such as mRNA stability and protein folding among others. Finally, we examine how different organisms or cell types, through this system, are able to coordinate physiological pathways to respond to a variety of stress or growth conditions.
Collapse
Affiliation(s)
- Fabian Hia
- Department of Medical Chemistry, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Osamu Takeuchi
- Department of Medical Chemistry, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
| |
Collapse
|
22
|
Specificity of RNA Folding and Its Association with Evolutionarily Adaptive mRNA Secondary Structures. GENOMICS PROTEOMICS & BIOINFORMATICS 2021; 19:882-900. [PMID: 33607297 PMCID: PMC9403030 DOI: 10.1016/j.gpb.2019.11.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 08/03/2019] [Accepted: 11/08/2019] [Indexed: 11/23/2022]
Abstract
The secondary structure is a fundamental feature of both noncoding and messenger RNAs. However, our understanding of the secondary structure of mRNA, especially that of the coding regions, remains elusive, likely due to translation and the lack of RNA-binding proteins that sustain the consensus structure, such as those that bind to noncoding RNA. Indeed, mRNA has recently been found to adopt diverse alternative structures, the overall functional significance of which remains untested. We hereby approached this problem by estimating the folding specificity, i.e., the probability that a fragment of RNA folds back to the same partner once refolded. We showed that the folding specificity of mRNA is lower than that of noncoding RNA and exhibits moderate evolutionary conservation. Notably, we found that specific rather than alternative folding is likely evolutionarily adaptive since specific folding is frequently associated with functionally important genes or sites within a gene. Additional analysis in combination with ribosome density suggests the ability to modulate ribosome movement as one potential functional advantage provided by specific folding. Our findings revealed a novel facet of the RNA structurome with important functional and evolutionary implications and indicated a potential method for distinguishing the mRNA secondary structures maintained by natural selection from molecular noise.
Collapse
|
23
|
Tang Y, Chen K, Song B, Ma J, Wu X, Xu Q, Wei Z, Su J, Liu G, Rong R, Lu Z, de Magalhães J, Rigden DJ, Meng J. m6A-Atlas: a comprehensive knowledgebase for unraveling the N6-methyladenosine (m6A) epitranscriptome. Nucleic Acids Res 2021; 49:D134-D143. [PMID: 32821938 PMCID: PMC7779050 DOI: 10.1093/nar/gkaa692] [Citation(s) in RCA: 189] [Impact Index Per Article: 63.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 08/05/2020] [Accepted: 08/09/2020] [Indexed: 12/25/2022] Open
Abstract
N 6-Methyladenosine (m6A) is the most prevalent RNA modification on mRNAs and lncRNAs. It plays a pivotal role during various biological processes and disease pathogenesis. We present here a comprehensive knowledgebase, m6A-Atlas, for unraveling the m6A epitranscriptome. Compared to existing databases, m6A-Atlas features a high-confidence collection of 442 162 reliable m6A sites identified from seven base-resolution technologies and the quantitative (rather than binary) epitranscriptome profiles estimated from 1363 high-throughput sequencing samples. It also offers novel features, such as; the conservation of m6A sites among seven vertebrate species (including human, mouse and chimp), the m6A epitranscriptomes of 10 virus species (including HIV, KSHV and DENV), the putative biological functions of individual m6A sites predicted from epitranscriptome data, and the potential pathogenesis of m6A sites inferred from disease-associated genetic mutations that can directly destroy m6A directing sequence motifs. A user-friendly graphical user interface was constructed to support the query, visualization and sharing of the m6A epitranscriptomes annotated with sites specifying their interaction with post-transcriptional machinery (RBP-binding, microRNA interaction and splicing sites) and interactively display the landscape of multiple RNA modifications. These resources provide fresh opportunities for unraveling the m6A epitranscriptomes. m6A-Atlas is freely accessible at: www.xjtlu.edu.cn/biologicalsciences/atlas.
Collapse
Affiliation(s)
- Yujiao Tang
- Department of Biological Sciences, Xi’an Jiaotong-Liverpool University, Suzhou, Jiangsu 215123, China
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, L7 8TX Liverpool, UK
| | - Kunqi Chen
- Department of Biological Sciences, Xi’an Jiaotong-Liverpool University, Suzhou, Jiangsu 215123, China
- Institute of Ageing & Chronic Disease, University of Liverpool, L7 8TX Liverpool, UK
| | - Bowen Song
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, L7 8TX Liverpool, UK
- Department of Mathematical Sciences, Xi’an Jiaotong-Liverpool University, Suzhou, Jiangsu 215123, China
| | - Jiongming Ma
- Department of Biological Sciences, Xi’an Jiaotong-Liverpool University, Suzhou, Jiangsu 215123, China
| | - Xiangyu Wu
- Department of Biological Sciences, Xi’an Jiaotong-Liverpool University, Suzhou, Jiangsu 215123, China
- Institute of Ageing & Chronic Disease, University of Liverpool, L7 8TX Liverpool, UK
| | - Qingru Xu
- Department of Biological Sciences, Xi’an Jiaotong-Liverpool University, Suzhou, Jiangsu 215123, China
| | - Zhen Wei
- Department of Biological Sciences, Xi’an Jiaotong-Liverpool University, Suzhou, Jiangsu 215123, China
| | - Jionglong Su
- Department of Mathematical Sciences, Xi’an Jiaotong-Liverpool University, Suzhou, Jiangsu 215123, China
| | - Gang Liu
- Department of Mathematical Sciences, Xi’an Jiaotong-Liverpool University, Suzhou, Jiangsu 215123, China
| | - Rong Rong
- Department of Biological Sciences, Xi’an Jiaotong-Liverpool University, Suzhou, Jiangsu 215123, China
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, L7 8TX Liverpool, UK
| | - Zhiliang Lu
- Department of Biological Sciences, Xi’an Jiaotong-Liverpool University, Suzhou, Jiangsu 215123, China
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, L7 8TX Liverpool, UK
| | | | - Daniel J Rigden
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, L7 8TX Liverpool, UK
| | - Jia Meng
- Department of Biological Sciences, Xi’an Jiaotong-Liverpool University, Suzhou, Jiangsu 215123, China
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, L7 8TX Liverpool, UK
- AI University Research Centre, Xi’an Jiaotong-Liverpool University, Suzhou, Jiangsu 215123, China
| |
Collapse
|
24
|
Zhang H, Shi X, Huang T, Zhao X, Chen W, Gu N, Zhang R. Dynamic landscape and evolution of m6A methylation in human. Nucleic Acids Res 2020; 48:6251-6264. [PMID: 32406913 PMCID: PMC7293016 DOI: 10.1093/nar/gkaa347] [Citation(s) in RCA: 181] [Impact Index Per Article: 45.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 04/23/2020] [Accepted: 04/24/2020] [Indexed: 01/03/2023] Open
Abstract
m6A is a prevalent internal modification in mRNAs and has been linked to the diverse effects on mRNA fate. To explore the landscape and evolution of human m6A, we generated 27 m6A methylomes across major adult tissues. These data reveal dynamic m6A methylation across tissue types, uncover both broadly or tissue-specifically methylated sites, and identify an unexpected enrichment of m6A methylation at non-canonical cleavage sites. A comparison of fetal and adult m6A methylomes reveals that m6A preferentially occupies CDS regions in fetal tissues. Moreover, the m6A sub-motifs vary between fetal and adult tissues or across tissue types. From the evolutionary perspective, we uncover that the selection pressure on m6A sites varies and depends on their genic locations. Unexpectedly, we found that ∼40% of the 3′UTR m6A sites are under negative selection, which is higher than the evolutionary constraint on miRNA binding sites, and much higher than that on A-to-I RNA modification. Moreover, the recently gained m6A sites in human populations are clearly under positive selection and associated with traits or diseases. Our work provides a resource of human m6A profile for future studies of m6A functions, and suggests a role of m6A modification in human evolutionary adaptation and disease susceptibility.
Collapse
Affiliation(s)
- Hui Zhang
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, PR China
| | - Xinrui Shi
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, PR China
| | - Tao Huang
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, PR China
| | - Xueni Zhao
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, PR China
| | - Wanying Chen
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, PR China
| | - Nannan Gu
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, PR China
| | - Rui Zhang
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, PR China.,RNA Biomedical Institute, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, PR China
| |
Collapse
|
25
|
An M, Wang H, Zhu Y. Mutations in m6A consensus motifs are suppressed in the m6A modified genes in human cancer cells. PLoS One 2020; 15:e0236882. [PMID: 32790688 PMCID: PMC7425885 DOI: 10.1371/journal.pone.0236882] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Accepted: 07/15/2020] [Indexed: 01/22/2023] Open
Abstract
N6-methyladenosine (m6A) is the most prevalent type of RNA modification. METTL3 in the methyltransferase complex is the core enzyme responsible for methylation. METTL3 selectively catalyzes the adenosines centered in the RRAC motif. Functional studies established that m6A could enhance the translation efficiency (TE) of modified genes by recruiting reader protein YTHDF1 and other initiation factors. We downloaded the m6A peaks in HeLa cells from a previous study and defined the m6A modified genes and sites. Ancestral mutations in the genic region fixed in the HeLa cell samples were defined using their mRNA-Seq data and the alignment between human and mouse genomes. Furthermore, in the small interfering (si)-METTL3 sample, the calculated TE foldchange of all genes was compared to that in the negative control. The TE of m6A genes was globally down-regulated in si-METTL3 versus control compared to the non-m6A genes. In m6A modified genes, RRAC motif mutations were suppressed compared to mutations in non-motif regions or non-m6A genes. Among the m6A genes, a fraction RRAC motif mutations negatively correlated with the TE foldchange (si-METTL3 versus control). The TE of m6A modified genes was enhanced in HeLa cells. RRAC motif mutations could potentially prevent methylation of adenosines and consequently abolish the enhanced translation. Such mutations in the RRAC motif might be deleterious. Accordingly, we observed lower fractions of mutations in RRAC motifs than in other regions. This prevention of mutations in the RRAC motif could be a strategy adopted by cancer cells to maintain the elevated translation of particular genes.
Collapse
Affiliation(s)
- Mingzi An
- Department of Gynaecology, Chengyang People's Hospital, Qingdao, Shandong, China
| | - Huiyun Wang
- Department of Oncology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
| | - Yingqian Zhu
- Department of Oncology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
- * E-mail:
| |
Collapse
|
26
|
Meer KM, Nelson PG, Xiong K, Masel J. High Transcriptional Error Rates Vary as a Function of Gene Expression Level. Genome Biol Evol 2020; 12:3754-3761. [PMID: 31841128 PMCID: PMC6988749 DOI: 10.1093/gbe/evz275] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/12/2019] [Indexed: 02/06/2023] Open
Abstract
Errors in gene transcription can be costly, and organisms have evolved to prevent their occurrence or mitigate their costs. The simplest interpretation of the drift barrier hypothesis suggests that species with larger population sizes would have lower transcriptional error rates. However, Escherichia coli seems to have a higher transcriptional error rate than species with lower effective population sizes, for example Saccharomyces cerevisiae. This could be explained if selection in E. coli were strong enough to maintain adaptations that mitigate the consequences of transcriptional errors through robustness, on a gene by gene basis, obviating the need for low transcriptional error rates and associated costs of global proofreading. Here, we note that if selection is powerful enough to evolve local robustness, selection should also be powerful enough to locally reduce error rates. We therefore predict that transcriptional error rates will be lower in highly abundant proteins on which selection is strongest. However, we only expect this result when error rates are high enough to significantly impact fitness. As expected, we find such a relationship between expression and transcriptional error rate for non-C→U errors in E. coli (especially G→A), but not in S. cerevisiae. We do not find this pattern for C→U changes in E. coli, presumably because most deamination events occurred during sample preparation, but do for C→U changes in S. cerevisiae, supporting the interpretation that C→U error rates estimated with an improved protocol, and which occur at rates comparable with E. coli non-C→U errors, are biological.
Collapse
Affiliation(s)
- Kendra M Meer
- Department of Ecology & Evolutionary Biology, University of Arizona.,Computational Bioscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Paul G Nelson
- Department of Ecology & Evolutionary Biology, University of Arizona
| | - Kun Xiong
- Department of Molecular & Cellular Biology, University of Arizona.,Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT
| | - Joanna Masel
- Department of Ecology & Evolutionary Biology, University of Arizona
| |
Collapse
|
27
|
Wang K, Jiang L, Zhang Y, Chen C. Progression of Thyroid Carcinoma Is Promoted by the m6A Methyltransferase METTL3 Through Regulating m 6A Methylation on TCF1. Onco Targets Ther 2020; 13:1605-1612. [PMID: 32158230 PMCID: PMC7044742 DOI: 10.2147/ott.s234751] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 02/04/2020] [Indexed: 12/17/2022] Open
Abstract
Objective This study aims to uncover the progression of thyroid carcinoma influenced by the m6A methyltransferase METTL3 through regulating m6A methylation on TCF1 mRNA and the activated Wnt pathway. Methods Thyroid carcinoma tissues and paracancerous ones were collected for detecting levels of METTL3 and TCF1. Potential correlation between levels of METTL3 and TCF1 was analyzed by Pearson analysis. Survival of thyroid carcinoma patients influenced by METTL3 level was assessed by Kaplan–Meier method. Regulatory effect of METTL3 on migratory ability in TPC-1 cells was examined by wound healing assay. The interaction between METTL3 with TCF1 and IGF2BP2 was verified by RNA-Binding Protein Immunoprecipitation (RIP) assay. Meanwhile, the activity of the Wnt pathway was reflected by TOP/FOP-Flash. At last, rescue experiments were conducted to clarify the involvement of TCF1 in phenotype changes of thyroid carcinoma cells that were regulated by METTL3. Results METTL3 and TCF1 were upregulated in thyroid carcinoma. Similarly, METTL3 was highly expressed in thyroid carcinoma cells as well. Kaplan–Meier method uncovered poor prognosis in thyroid carcinoma patients expressing a high level of METTL3. Silence of METTL3 inhibited migratory ability and Wnt activity in TPC-1 cells. RIP assay confirmed the interaction between TCF1 and METTL3 or IGF2BP2. Moreover, METTL3 positively regulated the enrichment abundance of TCF1 in anti-IGF2BP2. Rescue experiments demonstrated that TCF1 was responsible for METTL3-regulated thyroid carcinoma progression via the m6A methylation. Conclusion Upregulated m6A methyltransferase METTL3 promotes the progression of thyroid carcinoma through m6A methylation on TCF1.
Collapse
Affiliation(s)
- Kejin Wang
- Department of Head and Neck Surgery, Cancer Hospital of University of Chinese Academy of Sciences, Key Laboratory of Head & Neck Cancer Translational Research of Zhejiang Province, Hangzhou, People's Republic of China
| | - Lin Jiang
- Department of Head and Neck Surgery, Cancer Hospital of University of Chinese Academy of Sciences, Key Laboratory of Head & Neck Cancer Translational Research of Zhejiang Province, Hangzhou, People's Republic of China
| | - Yan Zhang
- Department of Head and Neck Surgery, Cancer Hospital of University of Chinese Academy of Sciences, Key Laboratory of Head & Neck Cancer Translational Research of Zhejiang Province, Hangzhou, People's Republic of China
| | - Chao Chen
- Department of Head and Neck Surgery, Cancer Hospital of University of Chinese Academy of Sciences, Key Laboratory of Head & Neck Cancer Translational Research of Zhejiang Province, Hangzhou, People's Republic of China
| |
Collapse
|
28
|
Jiang D, Zhang J. The preponderance of nonsynonymous A-to-I RNA editing in coleoids is nonadaptive. Nat Commun 2019; 10:5411. [PMID: 31776345 PMCID: PMC6881472 DOI: 10.1038/s41467-019-13275-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 10/31/2019] [Indexed: 01/24/2023] Open
Abstract
A-to-I editing enzymatically converts the base adenosine (A) in RNA molecules to inosine (I), which is recognized as guanine (G) in translation. Exceptionally abundant A-to-I editing was recently discovered in the neural tissues of coleoids (octopuses, squids, and cuttlefishes), with a greater fraction of nonsynonymous sites than synonymous sites subject to high levels of editing. Although this phenomenon is thought to indicate widespread adaptive editing, its potential advantage is unknown. Here we propose an alternative, nonadaptive explanation. Specifically, increasing the cellular editing activity permits some otherwise harmful G-to-A nonsynonymous substitutions, because the As are edited to Is at sufficiently high levels. These high editing levels are constrained upon substitutions, resulting in the predominance of nonsynonymous editing at highly edited sites. Our evidence for this explanation suggests that the prevalent nonsynonymous editing in coleoids is generally nonadaptive, as in species with much lower editing activities. The neural tissues of coleoids have a greater fraction of nonsynonymous sites than synonymous sites subject to high levels of A-to-I RNA editing, a pattern thought to indicate widespread adaptive editing. Here the authors propose and provide evidence for an alternative, nonadaptive explanation.
Collapse
Affiliation(s)
- Daohan Jiang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, USA.
| |
Collapse
|
29
|
Ho AT, Hurst LD. In eubacteria, unlike eukaryotes, there is no evidence for selection favouring fail-safe 3' additional stop codons. PLoS Genet 2019; 15:e1008386. [PMID: 31527909 PMCID: PMC6764699 DOI: 10.1371/journal.pgen.1008386] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 09/27/2019] [Accepted: 08/27/2019] [Indexed: 12/23/2022] Open
Abstract
Errors throughout gene expression are likely deleterious, hence genomes are under selection to ameliorate their consequences. Additional stop codons (ASCs) are in-frame nonsense ‘codons’ downstream of the primary stop which may be read by translational machinery should the primary stop have been accidentally read through. Prior evidence in several eukaryotes suggests that ASCs are selected to prevent potentially-deleterious consequences of read-through. We extend this evidence showing that enrichment of ASCs is common but not universal for single cell eukaryotes. By contrast, there is limited evidence as to whether the same is true in other taxa. Here, we provide the first systematic test of the hypothesis that ASCs act as a fail-safe mechanism in eubacteria, a group with high read-through rates. Contra to the predictions of the hypothesis we find: there is paucity, not enrichment, of ASCs downstream; substitutions that degrade stops are more frequent in-frame than out-of-frame in 3’ sequence; highly expressed genes are no more likely to have ASCs than lowly expressed genes; usage of the leakiest primary stop (TGA) in highly expressed genes does not predict ASC enrichment even compared to usage of non-leaky stops (TAA) in lowly expressed genes, beyond downstream codon +1. Any effect at the codon immediately proximal to the primary stop can be accounted for by a preference for a T/U residue immediately following the stop, although if anything, TT- and TC- starting codons are preferred. We conclude that there is no compelling evidence for ASC selection in eubacteria. This presents an unusual case in which the same error could be solved by the same mechanism in eukaryotes and prokaryotes but is not. We discuss two possible explanations: that, owing to the absence of nonsense mediated decay, bacteria may solve read-through via gene truncation and in eukaryotes certain prion states cause raised read-through rates. In all organisms, gene expression is error-prone. One such error, translational read-through, occurs where the primary stop codon of an expressed gene is missed by the translational machinery. Failure to terminate is likely to be costly, hence genomes are under selection to prevent this from happening. One proposed error-proofing strategy involves in-frame proximal additional stop codons (ASCs) which may act as a ‘fail-safe’ mechanism by providing another opportunity for translation to terminate. There is evidence for ASC enrichment in several eukaryotes. We extend this evidence showing it to be common but not universal in single celled eukaryotes. However, the situation in bacteria is poorly understood, despite bacteria having high read-through rates. Here, we test the fail-safe hypothesis within a broad range of bacteria. To our surprise, we find that not only are ASCs not enriched, but they may even be selected against. This provides evidence for an unusual circumstance where eukaryotes and prokaryotes could solve the same problem the same way but don’t. What are we to make of this? We suggest that if read-through is the problem, ASCs are not necessarily the expected solution. Owing to the absence of nonsense-mediated decay, a process that makes gene truncation in eukaryotes less viable, we propose bacteria may rescue a leaky stop by mutation that creates a new stop upstream. Alternatively, raised read-through rates in some particular conditions in eukaryotes might explain the difference.
Collapse
Affiliation(s)
- Alexander T. Ho
- Milner Centre for Evolution, University of Bath, Bath, United Kingdom
- * E-mail:
| | - Laurence D. Hurst
- Milner Centre for Evolution, University of Bath, Bath, United Kingdom
| |
Collapse
|
30
|
Zhang Z, Chen LQ, Zhao YL, Yang CG, Roundtree IA, Zhang Z, Ren J, Xie W, He C, Luo GZ. Single-base mapping of m 6A by an antibody-independent method. SCIENCE ADVANCES 2019; 5:eaax0250. [PMID: 31281898 PMCID: PMC6609220 DOI: 10.1126/sciadv.aax0250] [Citation(s) in RCA: 230] [Impact Index Per Article: 46.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 05/30/2019] [Indexed: 05/12/2023]
Abstract
N 6-methyladenosine (m6A) is one of the most abundant messenger RNA modifications in eukaryotes involved in various pivotal processes of RNA metabolism. The most popular high-throughput m6A identification method depends on the anti-m6A antibody but suffers from poor reproducibility and limited resolution. Exact location information is of great value for understanding the dynamics, machinery, and functions of m6A. Here, we developed a precise and high-throughput antibody-independent m6A identification method based on the m6A-sensitive RNA endoribonuclease recognizing ACA motif (m6A-sensitive RNA-Endoribonuclease-Facilitated sequencing or m6A-REF-seq). Whole-transcriptomic, single-base m6A maps generated by m6A-REF-seq quantitatively displayed an explicit distribution pattern with enrichment near stop codons. We used independent methods to validate methylation status and abundance of individual m6A sites, confirming the high reliability and accuracy of m6A-REF-seq. We applied this method on five tissues from human, mouse, and rat, showing that m6A sites are conserved with single-nucleotide specificity and tend to cluster among species.
Collapse
Affiliation(s)
- Zhang Zhang
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Li-Qian Chen
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Yu-Li Zhao
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Cai-Guang Yang
- Laboratory of Chemical Biology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Ian A. Roundtree
- Department of Chemistry and Department of Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, Howard Hughes Medical Institute, University of Chicago, Chicago, IL, USA
| | - Zijie Zhang
- Department of Chemistry and Department of Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, Howard Hughes Medical Institute, University of Chicago, Chicago, IL, USA
| | - Jian Ren
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Wei Xie
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Chuan He
- Department of Chemistry and Department of Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, Howard Hughes Medical Institute, University of Chicago, Chicago, IL, USA
| | - Guan-Zheng Luo
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
- Corresponding author.
| |
Collapse
|
31
|
Li C, Zhang J. Stop-codon read-through arises largely from molecular errors and is generally nonadaptive. PLoS Genet 2019; 15:e1008141. [PMID: 31120886 PMCID: PMC6550407 DOI: 10.1371/journal.pgen.1008141] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 06/05/2019] [Accepted: 04/16/2019] [Indexed: 12/02/2022] Open
Abstract
Stop-codon read-through refers to the phenomenon that a ribosome goes past the stop codon and continues translating into the otherwise untranslated region (UTR) of a transcript. Recent ribosome-profiling experiments in eukaryotes uncovered widespread stop-codon read-through that also varies among tissues, prompting the adaptive hypothesis that stop-codon read-through is an important, regulated mechanism for generating proteome diversity. Here we propose and test a competing hypothesis that stop-codon read-through arises mostly from molecular errors and is largely nonadaptive. The error hypothesis makes distinct predictions about the probability of read-through, frequency of sequence motifs for read-through, and conservation of the read-through region, each of which is supported by genome-scale data from yeasts and fruit flies. Thus, except for the few cases with demonstrated functions, stop-codon read-through is generally nonadaptive. This finding, along with other molecular errors recently quantified, reveals a much less precise or orderly cellular life than is commonly thought.
Collapse
Affiliation(s)
- Chuan Li
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, United States of America
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, United States of America
| |
Collapse
|
32
|
Chu D, Wei L. Human cancer cells compensate the genes unfavorable for translation by N 6-methyladenosine modification and enhance their translation efficiency. Transl Cancer Res 2019; 8:499-508. [PMID: 35116782 PMCID: PMC8797713 DOI: 10.21037/tcr.2019.03.04] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 03/05/2019] [Indexed: 11/06/2022]
Abstract
BACKGROUND N 6-methyladenosine (m6A) is the methylation of RNA adenosines that participates in multiple biological processes, such as facilitating translation of host genes via the reader protein YTHDF1. The core writer protein of m6A in humans is METTL3. METHODS We utilized YTHDF1 target genes and normal or si-METTL3 NGS (next-generation sequencing) data from HeLa cells generated by a previous work and collected known human oncogenes from a website. We evaluated the translation capability of these m6A genes or oncogenes by comparing their mRNA lengths and codon usage bias. Additionally, we calculated the translation efficiency of all genes expressed in the normal or si-METTL3 HeLa cells using NGS data. RESULTS The m6A genes are enriched in oncogenes compared to the non-m6A genes. We observed significantly longer mRNA lengths for the m6A genes, especially for the oncogenes. We also observed stronger codon usage bias for the m6A genes than for the non-m6A genes. We provided evidence that the longer mRNA lengths and stronger codon bias were unfavorable for translation. However, this disadvantage was compensated by m6A modification because the m6A genes but not the non-m6A genes showed higher translation efficiencies in normal cells than in si-METTL3 cells. CONCLUSIONS HeLa cells compensate for genes unfavorable for translation by m6A modification and enhance their translation efficiency. This compensation could originally have been designed for oncogenes, since we observed enrichment of m6A genes in the oncogenes. If oncogenes modified by m6A obtain higher translation efficiencies and eventually facilitate cancer cell proliferation, then this strategy may be used by cancers for rapid cell growth.
Collapse
Affiliation(s)
- Duan Chu
- College of Life Sciences, Beijing Normal University, Beijing 100000, China
| | - Lai Wei
- College of Life Sciences, Beijing Normal University, Beijing 100000, China
| |
Collapse
|
33
|
Abstract
Although the neutral theory of molecular evolution was proposed to explain DNA and protein sequence evolution, in principle it could also explain phenotypic evolution. Nevertheless, overall, phenotypes should be less likely than genotypes to evolve neutrally. I propose that, when phenotypic traits are stratified according to a hierarchy of biological organization, the fraction of evolutionary changes in phenotype that are adaptive rises with the phenotypic level considered. Consistently, molecular traits are frequently found to evolve neutrally whereas a large, random set of organismal traits were recently reported to vary largely adaptively. Many more studies of unbiased samples of phenotypic traits are needed to test the general validity of this hypothesis.
Collapse
Affiliation(s)
- Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI
| |
Collapse
|
34
|
Xu C, Park JK, Zhang J. Evidence that alternative transcriptional initiation is largely nonadaptive. PLoS Biol 2019; 17:e3000197. [PMID: 30883542 PMCID: PMC6438578 DOI: 10.1371/journal.pbio.3000197] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 03/28/2019] [Accepted: 03/12/2019] [Indexed: 12/22/2022] Open
Abstract
Alternative transcriptional initiation (ATI) refers to the frequent observation that one gene has multiple transcription start sites (TSSs). Although this phenomenon is thought to be adaptive, the specific advantage is rarely known. Here, we propose that each gene has one optimal TSS and that ATI arises primarily from imprecise transcriptional initiation that could be deleterious. This error hypothesis predicts that (i) the TSS diversity of a gene reduces with its expression level; (ii) the fractional use of the major TSS increases, but that of each minor TSS decreases, with the gene expression level; and (iii) cis-elements for major TSSs are selectively constrained, while those for minor TSSs are not. By contrast, the adaptive hypothesis does not make these predictions a priori. Our analysis of human and mouse transcriptomes confirms each of the three predictions. These and other findings strongly suggest that ATI predominantly results from molecular errors, requiring a major revision of our understanding of the precision and regulation of transcription. The transcription of a gene may start from one of several transcription start sites, a phenomenon known as alternative transcriptional initiation. Contrary to common belief, this study shows that variation of the transcription start site of a given gene is nonadaptive and is largely attributable to transcriptional initiation error that is typically deleterious. Multiple surveys of transcriptional initiation showed that mammalian genes typically have multiple transcription start sites such that transcription is initiated from any one of these sites. Many researchers believe that this phenomenon is adaptive because it allows production of multiple transcripts, from the same gene, that potentially vary in function or post-transcriptional regulation. Nevertheless, it is also possible that each gene has only one optimal transcription start site and that alternative transcriptional initiation arises primarily from molecular errors that are slightly deleterious. This error hypothesis makes a series of predictions about the amount of transcription start site diversity per gene, relative uses of the various start sites of a gene, among-tissue and across-species differences in start site usage, and the evolutionary conservation of cis-regulatory elements of various start sites, all of which are verified in our analyses of genome-wide transcription start site data from the human and mouse. These findings strongly suggest that alternative transcriptional initiation largely reflects molecular errors instead of molecular adaptations and require a rethink of the precision and regulation of transcription.
Collapse
Affiliation(s)
- Chuan Xu
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Joong-Ki Park
- Division of EcoScience, Ewha Womans University, Seoul, Republic of Korea
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
| |
Collapse
|
35
|
Abstract
C-to-U RNA editing enzymatically converts the base C to U in RNA molecules and could lead to nonsynonymous changes when occurring in coding regions. Hundreds to thousands of coding sites were recently found to be C-to-U edited or editable in humans, but the biological significance of this phenomenon is elusive. Here, we test the prevailing hypothesis that nonsynonymous editing is beneficial because it provides a means for tissue- or time-specific regulation of protein function that may be hard to accomplish by mutations due to pleiotropy. The adaptive hypothesis predicts that the fraction of sites edited and the median proportion of RNA molecules edited (i.e., editing level) are both higher for nonsynonymous than synonymous editing. However, our empirical observations are opposite to these predictions. Furthermore, the frequency of nonsynonymous editing, relative to that of synonymous editing, declines as genes become functionally more important or evolutionarily more constrained, and the nonsynonymous editing level at a site is negatively correlated with the evolutionary conservation of the site. Together, these findings refute the adaptive hypothesis; they instead indicate that the reported C-to-U coding RNA editing is mostly slightly deleterious or neutral, probably resulting from off-target activities of editing enzymes. Along with similar conclusions on the more prevalent A-to-I editing and m6A modification of coding RNAs, our study suggests that, at least in humans, most events of each type of posttranscriptional coding RNA modification likely manifest cellular errors rather than adaptations, demanding a paradigm shift in the research of posttranscriptional modification.
Collapse
Affiliation(s)
- Zhen Liu
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China.,Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI
| |
Collapse
|
36
|
Mettl3 Regulates Osteogenic Differentiation and Alternative Splicing of Vegfa in Bone Marrow Mesenchymal Stem Cells. Int J Mol Sci 2019; 20:ijms20030551. [PMID: 30696066 PMCID: PMC6387109 DOI: 10.3390/ijms20030551] [Citation(s) in RCA: 98] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Revised: 01/20/2019] [Accepted: 01/25/2019] [Indexed: 12/16/2022] Open
Abstract
Bone mesenchymal stem cells (BMSCs) can be a useful cell resource for developing biological treatment strategies for bone repair and regeneration, and their therapeutic applications hinge on an understanding of their physiological characteristics. N6-methyl-adenosine (m6A) is the most prevalent internal chemical modification of mRNAs and has recently been reported to play important roles in cell lineage differentiation and development. However, little is known about the role of m6A modification in the cell differentiation of BMSCs. To address this issue, we investigated the expression of N6-adenosine methyltransferases (Mettl3 and Mettl14) and demethylases (Fto and Alkbh5) and found that Mettl3 was upregulated in BMSCs undergoing osteogenic induction. Furthermore, we knocked down Mettl3 and demonstrated that Mettl3 knockdown decreased the expression of bone formation-related genes, such as Runx2 and Osterix. The alkaline phosphatase (ALP) activity and the formation of mineralized nodules also decreased after Mettl3 knockdown. RNA sequencing analysis revealed that a vast number of genes affected by Mettl3 knockdown were associated with osteogenic differentiation and bone mineralization. Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis revealed that the phosphatidylinositol 3-kinase/AKT (PI3K-Akt) signaling pathway appeared to be one of the most enriched pathways, and Western blotting results showed that Akt phosphorylation was significantly reduced after Mettl3 knockdown. Mettl3 has been reported to play an important role in regulating alternative splicing of mRNA in previous research. In this study, we found that Mettl3 knockdown not only reduced the expression of Vegfa but also decreased the level of its splice variants, vegfa-164 and vegfa-188, in Mettl3-deficient BMSCs. These findings might contribute to novel progress in understanding the role of epitranscriptomic regulation in the osteogenic differentiation of BMSCs and provide a promising perspective for new therapeutic strategies for bone regeneration.
Collapse
|
37
|
Xu C, Zhang J. Alternative Polyadenylation of Mammalian Transcripts Is Generally Deleterious, Not Adaptive. Cell Syst 2018; 6:734-742.e4. [PMID: 29886108 DOI: 10.1016/j.cels.2018.05.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 03/27/2018] [Accepted: 05/09/2018] [Indexed: 01/07/2023]
Abstract
Alternative polyadenylation (APA) produces from the same gene multiple mature RNAs with varying 3' ends. Although APA is commonly believed to generate beneficial functional diversity and be adaptive, we hypothesize that most genes have one optimal polyadenylation site and that APA is caused largely by deleterious polyadenylation errors. The error hypothesis, but not the adaptive hypothesis, predicts that, as the expression level of a gene increases, its polyadenylation diversity declines, relative use of the major (presumably optimal) polyadenylation site increases, and that of each minor (presumably nonoptimal) site decreases. It further predicts that the number of polyadenylation signals per gene is smaller than the random expectation and that polyadenylation signals for major but not minor sites are under purifying selection. All of these predictions are confirmed in mammals, suggesting that numerous defective RNAs are produced in normal cells, many phenotypic variations at the molecular level are nonadaptive, and cellular life is noisier than is appreciated.
Collapse
Affiliation(s)
- Chuan Xu
- College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China; Department of Ecology and Evolutionary Biology, University of Michigan, 4018 Biological Science Building, 1105 North University Avenue, Ann Arbor, MI 48109, USA
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, 4018 Biological Science Building, 1105 North University Avenue, Ann Arbor, MI 48109, USA.
| |
Collapse
|