N6-Methyladenosine

{{short description|Modification in mRNA, DNA}} {{DISPLAYTITLE:''N''⁶-Methyladenosine}} {{Chembox | Name = ''N''⁶-Methyladenosine | ImageFile = N6-Methyladenosine.svg | ImageSize = 150px | IUPACName = ''N''⁶-Methyladenosine | SystematicName = (2''R'',3''S'',4''R'',5''R'')-2-(Hydroxymethyl)-5-[6-(methylamino)-9''H''-purin-9-yl]oxolane-2,3-diol | OtherNames = m⁶A, 6mA |Section1={{Chembox Identifiers | CASNo = 1867-73-8 | CASNo_Ref = {{cascite|correct|CAS}} | UNII_Ref = {{fdacite|correct|FDA}} | UNII = CLE6G00625 | PubChem = 102175 | ChEBI = 21891 | ChemSpiderID = 92307 | SMILES = n2c1c(ncnc1NC)n(c2)[C@@H]3O[C@@H]([C@@H](O)[C@H]3O)CO | StdInChI = 1S/C11H15N5O4/c1-12-9-6-10(14-3-13-9)16(4-15-6)11-8(19)7(18)5(2-17)20-11/h3-5,7-8,11,17-19H,2H2,1H3,(H,12,13,14)/t5-,7-,8-,11-/m1/s1 | StdInChIKey = VQAYFKKCNSOZKM-IOSLPCCCSA-N }} |Section2={{Chembox Properties | C=11 | H=15 | N=5 | O=4 | Appearance = | Density = | MeltingPt = | BoilingPt = | Solubility = }} |Section3={{Chembox Hazards | MainHazards = | FlashPt = | AutoignitionPt = }} }} '''''N''⁶-Methyladenosine''' ('''m⁶A''') was originally identified and partially characterised in the 1970s,<ref name="pmid1128665" /><ref name="pmid4372599" /><ref name="pmid232187" /><ref name="pmid196091" /> and is an abundant modification in mRNA and DNA.<ref>{{cite journal | vauthors = Ji P, Wang X, Xie N, Li Y | title = N6-Methyladenosine in RNA and DNA: An Epitranscriptomic and Epigenetic Player Implicated in Determination of Stem Cell Fate | journal = Stem Cells International | volume = 2018 | article-number = 3256524 | year = 2018 | pmid = 30405719 | pmc = 6199872 | doi = 10.1155/2018/3256524 | doi-access = free }}</ref> It is found within some viruses,<ref name="pmid196091">{{cite journal | vauthors = Beemon K, Keith J | title = Localization of N6-methyladenosine in the Rous sarcoma virus genome | journal = Journal of Molecular Biology | volume = 113 | issue = 1 | pages = 165–179 | date = June 1977 | pmid = 196091 | doi = 10.1016/0022-2836(77)90047-X }}</ref><ref name="pmid232187">{{cite journal | vauthors = Aloni Y, Dhar R, Khoury G | title = Methylation of nuclear simian virus 40 RNAs | journal = Journal of Virology | volume = 32 | issue = 1 | pages = 52–60 | date = October 1979 | pmid = 232187 | pmc = 353526 | doi = 10.1128/JVI.32.1.52-60.1979 }}</ref><ref>{{cite journal | vauthors = Courtney DG, Kennedy EM, Dumm RE, Bogerd HP, Tsai K, Heaton NS, Cullen BR | title = Epitranscriptomic Enhancement of Influenza A Virus Gene Expression and Replication | journal = Cell Host & Microbe | volume = 22 | issue = 3 | pages = 377–386.e5 | date = September 2017 | pmid = 28910636 | doi = 10.1016/j.chom.2017.08.004 | pmc = 5615858 }}</ref><ref>{{cite journal | vauthors = Gokhale NS, McIntyre AB, McFadden MJ, Roder AE, Kennedy EM, Gandara JA, Hopcraft SE, Quicke KM, Vazquez C, Willer J, Ilkayeva OR, Law BA, Holley CL, Garcia-Blanco MA, Evans MJ, Suthar MS, Bradrick SS, Mason CE, Horner SM | display-authors = 6 | title = N6-Methyladenosine in Flaviviridae Viral RNA Genomes Regulates Infection | language = English | journal = Cell Host & Microbe | volume = 20 | issue = 5 | pages = 654–665 | date = November 2016 | pmid = 27773535 | pmc = 5123813 | doi = 10.1016/j.chom.2016.09.015 }}</ref> and most eukaryotes including mammals,<ref name="pmid4372599">{{cite journal | vauthors = Desrosiers R, Friderici K, Rottman F | title = Identification of methylated nucleosides in messenger RNA from Novikoff hepatoma cells | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 71 | issue = 10 | pages = 3971–3975 | date = October 1974 | pmid = 4372599 | pmc = 434308 | doi = 10.1073/pnas.71.10.3971 | doi-access = free | bibcode = 1974PNAS...71.3971D }}</ref><ref name="pmid1128665">{{cite journal | vauthors = Adams JM, Cory S | title = Modified nucleosides and bizarre 5'-termini in mouse myeloma mRNA | journal = Nature | volume = 255 | issue = 5503 | pages = 28–33 | date = May 1975 | pmid = 1128665 | doi = 10.1038/255028a0 | s2cid = 4199864 | doi-access = free | bibcode = 1975Natur.255...28A }}</ref><ref name="pmid174715">{{cite journal | vauthors = Wei CM, Gershowitz A, Moss B | title = 5'-Terminal and internal methylated nucleotide sequences in HeLa cell mRNA | journal = Biochemistry | volume = 15 | issue = 2 | pages = 397–401 | date = January 1976 | pmid = 174715 | doi = 10.1021/bi00647a024 }}</ref><ref name="pmid1168101">{{cite journal | vauthors = Perry RP, Kelley DE, Friderici K, Rottman F | title = The methylated constituents of L cell messenger RNA: evidence for an unusual cluster at the 5' terminus | journal = Cell | volume = 4 | issue = 4 | pages = 387–394 | date = April 1975 | pmid = 1168101 | doi = 10.1016/0092-8674(75)90159-2 | doi-access = free }}</ref> insects,<ref name="pmid418182">{{cite journal | vauthors = Levis R, Penman S | title = 5'-terminal structures of poly(A)+ cytoplasmic messenger RNA and of poly(A)+ and poly(A)- heterogeneous nuclear RNA of cells of the dipteran Drosophila melanogaster | journal = Journal of Molecular Biology | volume = 120 | issue = 4 | pages = 487–515 | date = April 1978 | pmid = 418182 | doi = 10.1016/0022-2836(78)90350-9 }}</ref> plants<ref name=Nich1>{{cite journal | vauthors =Nichols JL | title = In maize poly(A)-containing RNA | year = 1979 | journal = Plant Science Letters | volume = 15 | issue = 4 | pages = 357–361 | doi = 10.1016/0304-4211(79)90141-X }}</ref><ref name="pmid476526">{{cite journal | vauthors = Kennedy TD, Lane BG | title = Wheat embryo ribonucleates. XIII. Methyl-substituted nucleoside constituents and 5'-terminal dinucleotide sequences in bulk poly(AR)-rich RNA from imbibing wheat embryos | journal = Canadian Journal of Biochemistry | volume = 57 | issue = 6 | pages = 927–931 | date = June 1979 | pmid = 476526 | doi = 10.1139/o79-112 }}</ref><ref name="pmid18505803">{{cite journal | vauthors = Zhong S, Li H, Bodi Z, Button J, Vespa L, Herzog M, Fray RG | title = MTA is an Arabidopsis messenger RNA adenosine methylase and interacts with a homolog of a sex-specific splicing factor | journal = The Plant Cell | volume = 20 | issue = 5 | pages = 1278–1288 | date = May 2008 | pmid = 18505803 | pmc = 2438467 | doi = 10.1105/tpc.108.058883 }}</ref> and yeast.<ref name="Clancy_2002">{{cite journal | vauthors = Clancy MJ, Shambaugh ME, Timpte CS, Bokar JA | title = Induction of sporulation in Saccharomyces cerevisiae leads to the formation of N6-methyladenosine in mRNA: a potential mechanism for the activity of the IME4 gene | journal = Nucleic Acids Research | volume = 30 | issue = 20 | pages = 4509–4518 | date = October 2002 | pmid = 12384598 | pmc = 137137 | doi = 10.1093/nar/gkf573 }}</ref><ref name="Bodi_2010">{{cite journal | vauthors = Bodi Z, Button JD, Grierson D, Fray RG | title = Yeast targets for mRNA methylation | journal = Nucleic Acids Research | volume = 38 | issue = 16 | pages = 5327–5335 | date = September 2010 | pmid = 20421205 | pmc = 2938207 | doi = 10.1093/nar/gkq266 }}</ref> It is also found in tRNA, rRNA, and small nuclear RNA (snRNA) as well as several long non-coding RNA, such as ''Xist''.<ref name="Meyer_2012">{{cite journal | vauthors = Meyer KD, Saletore Y, Zumbo P, Elemento O, Mason CE, Jaffrey SR | title = Comprehensive analysis of mRNA methylation reveals enrichment in 3' UTRs and near stop codons | journal = Cell | volume = 149 | issue = 7 | pages = 1635–1646 | date = June 2012 | pmid = 22608085 | pmc = 3383396 | doi = 10.1016/j.cell.2012.05.003 }}</ref><ref name="Dominissini_2012">{{cite journal | vauthors = Dominissini D, Moshitch-Moshkovitz S, Schwartz S, Salmon-Divon M, Ungar L, Osenberg S, Cesarkas K, Jacob-Hirsch J, Amariglio N, Kupiec M, Sorek R, Rechavi G | display-authors = 6 | title = Topology of the human and mouse m6A RNA methylomes revealed by m6A-seq | journal = Nature | volume = 485 | issue = 7397 | pages = 201–206 | date = April 2012 | pmid = 22575960 | doi = 10.1038/nature11112 | s2cid = 3517716 | bibcode = 2012Natur.485..201D }}</ref>

The methylation of adenosine (on RNA) is directed by a large m⁶A methyltransferase complex containing METTL3, which is the subunit that binds ''S''-adenosyl-<small>L</small>-methionine (SAM).<ref name="pmid9409616">{{cite journal | vauthors = Bokar JA, Shambaugh ME, Polayes D, Matera AG, Rottman FM | title = Purification and cDNA cloning of the AdoMet-binding subunit of the human mRNA (N6-adenosine)-methyltransferase | journal = RNA | volume = 3 | issue = 11 | pages = 1233–1247 | date = November 1997 | pmid = 9409616 | pmc = 1369564 }}</ref> ''In vitro'', this methyltransferase complex preferentially methylates RNA oligonucleotides containing GGACU<ref name="pmid2216767">{{cite journal | vauthors = Harper JE, Miceli SM, Roberts RJ, Manley JL | title = Sequence specificity of the human mRNA N6-adenosine methylase in vitro | journal = Nucleic Acids Research | volume = 18 | issue = 19 | pages = 5735–5741 | date = October 1990 | pmid = 2216767 | pmc = 332308 | doi = 10.1093/nar/18.19.5735 }}</ref> and a similar preference was identified ''in vivo'' in mapped m⁶A sites in Rous sarcoma virus genomic RNA<ref name="pmid3016525">{{cite journal | vauthors = Kane SE, Beemon K | title = Precise localization of m6A in Rous sarcoma virus RNA reveals clustering of methylation sites: implications for RNA processing | journal = Molecular and Cellular Biology | volume = 5 | issue = 9 | pages = 2298–2306 | date = September 1985 | pmid = 3016525 | pmc = 366956 | doi = 10.1128/mcb.5.9.2298 }}</ref> and in bovine prolactin mRNA.<ref name="pmid6592581">{{cite journal | vauthors = Horowitz S, Horowitz A, Nilsen TW, Munns TW, Rottman FM | title = Mapping of N6-methyladenosine residues in bovine prolactin mRNA | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 81 | issue = 18 | pages = 5667–5671 | date = September 1984 | pmid = 6592581 | pmc = 391771 | doi = 10.1073/pnas.81.18.5667 | doi-access = free | bibcode = 1984PNAS...81.5667H }}</ref> More recent studies have characterized other key components of the m⁶A methyltransferase complex in mammals, including METTL14,<ref name=":0">{{cite journal | vauthors = Liu J, Yue Y, Han D, Wang X, Fu Y, Zhang L, Jia G, Yu M, Lu Z, Deng X, Dai Q, Chen W, He C | display-authors = 6 | title = A METTL3-METTL14 complex mediates mammalian nuclear RNA N6-adenosine methylation | journal = Nature Chemical Biology | volume = 10 | issue = 2 | pages = 93–95 | date = February 2014 | pmid = 24316715 | pmc = 3911877 | doi = 10.1038/nchembio.1432 }}</ref><ref>{{cite journal | vauthors = Wang Y, Li Y, Toth JI, Petroski MD, Zhang Z, Zhao JC | title = N6-methyladenosine modification destabilizes developmental regulators in embryonic stem cells | journal = Nature Cell Biology | volume = 16 | issue = 2 | pages = 191–198 | date = February 2014 | pmid = 24394384 | pmc = 4640932 | doi = 10.1038/ncb2902 }}</ref> Wilms tumor 1 associated protein (WTAP),<ref name=":0" /><ref>{{cite journal | vauthors = Ping XL, Sun BF, Wang L, Xiao W, Yang X, Wang WJ, Adhikari S, Shi Y, Lv Y, Chen YS, Zhao X, Li A, Yang Y, Dahal U, Lou XM, Liu X, Huang J, Yuan WP, Zhu XF, Cheng T, Zhao YL, Wang X, Rendtlew Danielsen JM, Liu F, Yang YG | display-authors = 6 | title = Mammalian WTAP is a regulatory subunit of the RNA N6-methyladenosine methyltransferase | journal = Cell Research | volume = 24 | issue = 2 | pages = 177–189 | date = February 2014 | pmid = 24407421 | pmc = 3915904 | doi = 10.1038/cr.2014.3 }}</ref> VIRMA<!-- former name KIAA1429 --><ref>{{cite journal | vauthors = Schwartz S, Mumbach MR, Jovanovic M, Wang T, Maciag K, Bushkin GG, Mertins P, Ter-Ovanesyan D, Habib N, Cacchiarelli D, Sanjana NE, Freinkman E, Pacold ME, Satija R, Mikkelsen TS, Hacohen N, Zhang F, Carr SA, Lander ES, Regev A | display-authors = 6 | title = Perturbation of m6A writers reveals two distinct classes of mRNA methylation at internal and 5' sites | journal = Cell Reports | volume = 8 | issue = 1 | pages = 284–296 | date = July 2014 | pmid = 24981863 | pmc = 4142486 | doi = 10.1016/j.celrep.2014.05.048 }}</ref> and METTL5.<ref>{{cite journal | vauthors = van Tran N, Ernst FG, Hawley BR, Zorbas C, Ulryck N, Hackert P, Bohnsack KE, Bohnsack MT, Jaffrey SR, Graille M, Lafontaine DL | display-authors = 6 | title = The human 18S rRNA m6A methyltransferase METTL5 is stabilized by TRMT112 | journal = Nucleic Acids Research | volume = 47 | issue = 15 | pages = 7719–7733 | date = September 2019 | pmid = 31328227 | pmc = 6735865 | doi = 10.1093/nar/gkz619 }}</ref> Following a 2010 speculation of m⁶A in mRNA being dynamic and reversible,<ref>{{cite journal | vauthors = He C | title = Grand challenge commentary: RNA epigenetics? | journal = Nature Chemical Biology | volume = 6 | issue = 12 | pages = 863–865 | date = December 2010 | pmid = 21079590 | doi = 10.1038/nchembio.482 }}</ref> the discovery of the first m⁶A demethylase, fat mass and obesity-associated protein (FTO) in 2011<ref>{{cite journal | vauthors = Jia G, Fu Y, Zhao X, Dai Q, Zheng G, Yang Y, Yi C, Lindahl T, Pan T, Yang YG, He C | display-authors = 6 | title = N6-methyladenosine in nuclear RNA is a major substrate of the obesity-associated FTO | journal = Nature Chemical Biology | volume = 7 | issue = 12 | pages = 885–887 | date = October 2011 | pmid = 22002720 | pmc = 3218240 | doi = 10.1038/nchembio.687 }}</ref> confirmed this hypothesis and revitalized the interests in the study of m⁶A. A second m⁶A demethylase alkB homolog 5 (ALKBH5) was later discovered as well.<ref>{{cite journal | vauthors = Zheng G, Dahl JA, Niu Y, Fedorcsak P, Huang CM, Li CJ, Vågbø CB, Shi Y, Wang WL, Song SH, Lu Z, Bosmans RP, Dai Q, Hao YJ, Yang X, Zhao WM, Tong WM, Wang XJ, Bogdan F, Furu K, Fu Y, Jia G, Zhao X, Liu J, Krokan HE, Klungland A, Yang YG, He C | display-authors = 6 | title = ALKBH5 is a mammalian RNA demethylase that impacts RNA metabolism and mouse fertility | journal = Molecular Cell | volume = 49 | issue = 1 | pages = 18–29 | date = January 2013 | pmid = 23177736 | pmc = 3646334 | doi = 10.1016/j.molcel.2012.10.015 }}</ref>

The biological functions of m⁶A are mediated through a group of RNA binding proteins that specifically recognize the methylated adenosine on RNA. These binding proteins are named m⁶A readers. The YT521-B homology (YTH) domain family of proteins (YTHDF1, YTHDF2, YTHDF3 and YTHDC1) have been characterized as direct m⁶A readers and have a conserved m⁶A-binding pocket.<ref name="Dominissini_2012" /><ref>{{cite journal | vauthors = Wang X, Lu Z, Gomez A, Hon GC, Yue Y, Han D, Fu Y, Parisien M, Dai Q, Jia G, Ren B, Pan T, He C | display-authors = 6 | title = N6-methyladenosine-dependent regulation of messenger RNA stability | journal = Nature | volume = 505 | issue = 7481 | pages = 117–120 | date = January 2014 | pmid = 24284625 | pmc = 3877715 | doi = 10.1038/nature12730 | bibcode = 2014Natur.505..117W }}</ref><ref>{{cite journal | vauthors = Wang X, Zhao BS, Roundtree IA, Lu Z, Han D, Ma H, Weng X, Chen K, Shi H, He C | display-authors = 6 | title = N(6)-methyladenosine Modulates Messenger RNA Translation Efficiency | journal = Cell | volume = 161 | issue = 6 | pages = 1388–1399 | date = June 2015 | pmid = 26046440 | pmc = 4825696 | doi = 10.1016/j.cell.2015.05.014 }}</ref><ref>{{cite journal | vauthors = Xu C, Wang X, Liu K, Roundtree IA, Tempel W, Li Y, Lu Z, He C, Min J | display-authors = 6 | title = Structural basis for selective binding of m6A RNA by the YTHDC1 YTH domain | journal = Nature Chemical Biology | volume = 10 | issue = 11 | pages = 927–929 | date = November 2014 | pmid = 25242552 | doi = 10.1038/nchembio.1654 }}</ref><ref>{{cite journal | vauthors = Xiao W, Adhikari S, Dahal U, Chen YS, Hao YJ, Sun BF, Sun HY, Li A, Ping XL, Lai WY, Wang X, Ma HL, Huang CM, Yang Y, Huang N, Jiang GB, Wang HL, Zhou Q, Wang XJ, Zhao YL, Yang YG | display-authors = 6 | title = Nuclear m(6)A Reader YTHDC1 Regulates mRNA Splicing | journal = Molecular Cell | volume = 61 | issue = 4 | pages = 507–519 | date = February 2016 | pmid = 26876937 | doi = 10.1016/j.molcel.2016.01.012 | doi-access = free }}</ref> Insulin-like growth factor-2 mRNA-binding proteins 1, 2, and 3 (IGF2BP1–3) are reported as a novel class of m⁶A readers.<ref name = "Huang_2018">{{cite journal | vauthors = Huang H, Weng H, Sun W, Qin X, Shi H, Wu H, Zhao BS, Mesquita A, Liu C, Yuan CL, Hu YC, Hüttelmaier S, Skibbe JR, Su R, Deng X, Dong L, Sun M, Li C, Nachtergaele S, Wang Y, Hu C, Ferchen K, Greis KD, Jiang X, Wei M, Qu L, Guan JL, He C, Yang J, Chen J | display-authors = 6 | title = Recognition of RNA N⁶-methyladenosine by IGF2BP proteins enhances mRNA stability and translation | journal = Nature Cell Biology | volume = 20 | issue = 3 | pages = 285–295 | date = March 2018 | pmid = 29476152 | pmc = 5826585 | doi = 10.1038/s41556-018-0045-z }}</ref> IGF2BPs use K homology (KH) domains to selectively recognize m6A-containing RNAs and promote their translation and stability.<ref name = "Huang_2018" /> These m⁶A readers, together with m⁶A methyltransferases (writers) and demethylases (erasers), establish a complex mechanism of m⁶A regulation in which writers and erasers determine the distributions of m⁶A on RNA, whereas readers mediate m⁶A-dependent functions. m⁶A has also been shown to mediate a structural switch termed m⁶A switch.<ref>{{cite journal | vauthors = Liu N, Dai Q, Zheng G, He C, Parisien M, Pan T | title = N(6)-methyladenosine-dependent RNA structural switches regulate RNA-protein interactions | journal = Nature | volume = 518 | issue = 7540 | pages = 560–564 | date = February 2015 | pmid = 25719671 | pmc = 4355918 | doi = 10.1038/nature14234 | bibcode = 2015Natur.518..560L }}</ref>

The specificity of m⁶A installation on mRNA is controlled by exon architecture and exon junction complexes. Exon junction complexes suppress m⁶A methylation near exon-exon junctions by packaging nearby RNA and protecting it from methylation by the m⁶A methyltransferase complex. m⁶A regions in long internal and terminal exons, away from exon-exon junctions and exon junction complexes, escape suppression and can be methylated by the methyltransferase complex.<ref name="He et al Science">{{cite journal | vauthors = He PC, Wei J, Dou X, Harada BT, Zhang Z, Ge R, Liu C, Zhang LS, Yu X, Wang S, Lyu R, Zou Z, Chen M, He C | display-authors = 6 | title = Exon architecture controls mRNA m⁶A suppression and gene expression | journal = Science | volume = 379 | issue = 6633 | pages = 677–682 | date = February 2023 | pmid = 36705538 | doi = 10.1126/science.abj9090 | pmc = 9990141 | bibcode = 2023Sci...379..677H }}</ref>

In eukaryotes, m⁶dA (DNA) is enriched in transcriptionally permissive regions, colocalizing with H3K4me3 nucleosomes. Production of m⁶dA is mediated by AMT1 (MTA1) and AMT6/7 (MTA9), which are distantly related to the RNA-methylating enzymes. The two form a complex and are inferred to exist in the common ancestor of extant eukaryotes, but have been lost in many lineages including animals and plants.<ref>{{cite journal |last1=Romero Charria |first1=Pedro |last2=Navarrete |first2=Cristina |last3=Ovchinnikov |first3=Vladimir |last4=Xu |first4=Lan |last5=Sarre |first5=Luke A. |last6=Shabardina |first6=Victoria |last7=Ksiezopolska |first7=Ewa |last8=Casacuberta |first8=Elena |last9=Lara-Astiaso |first9=David |last10=Sebé-Pedrós |first10=Arnau |last11=de Mendoza |first11=Alex |title=Adenine DNA methylation associated with transcriptionally permissive chromatin is widespread across eukaryotes |journal=Nature Genetics |date=18 November 2025 |doi=10.1038/s41588-025-02409-6 |doi-access=free|hdl=10261/423887 |hdl-access=free }}</ref>

== In eukaryotes ==

=== Yeast ===

In budding yeast (''Saccharomyces cerevisiae''), the expression of the homologue of METTL3, IME4, is induced in diploid cells in response to nitrogen and fermentable carbon source starvation and is required for mRNA methylation and the initiation of correct meiosis and sporulation.<ref name="Clancy_2002"/><ref name="Bodi_2010"/> mRNAs of IME1 and IME2, key early regulators of meiosis, are known to be targets for methylation, as are transcripts of IME4 itself.<ref name="Bodi_2010"/>

=== Plants ===

In plants, the majority of the m⁶A is found within 150 nucleotides before the start of the poly(A) tail.<ref name="Bodi_2012">{{cite journal | vauthors = Bodi Z, Zhong S, Mehra S, Song J, Graham N, Li H, May S, Fray RG | display-authors = 6 | title = Adenosine Methylation in Arabidopsis mRNA is Associated with the 3' End and Reduced Levels Cause Developmental Defects | journal = Frontiers in Plant Science | volume = 3 | page = 48 | year = 2012 | pmid = 22639649 | pmc = 3355605 | doi = 10.3389/fpls.2012.00048 | doi-access = free }}</ref>

Mutations of MTA, the ''Arabidopsis thaliana'' homologue of METTL3, results in embryo arrest at the globular stage. A >90% reduction of m⁶A levels in mature plants leads to dramatically altered growth patterns and floral homeotic abnormalities.<ref name="Bodi_2012"/>

=== Mammals ===

Mapping of m⁶A in human and mouse RNA has identified over 18,000 m⁶A sites in the transcripts of more than 7,000 human genes with a consensus sequence of [G/A/U][G>A]m⁶AC[U>A/C]<ref name="Meyer_2012"/><ref name="Dominissini_2012"/><ref name="Sun_2016">{{cite journal | vauthors = Sun WJ, Li JH, Liu S, Wu J, Zhou H, Qu LH, Yang JH | title = RMBase: a resource for decoding the landscape of RNA modifications from high-throughput sequencing data | journal = Nucleic Acids Research | volume = 44 | issue = D1 | pages = D259–D265 | date = January 2016 | pmid = 26464443 | pmc = 4702777 | doi = 10.1093/nar/gkv1036 }}</ref> consistent with the previously identified motif. The localization of individual m⁶A sites in many mRNAs is highly similar between human and mouse,<ref name="Meyer_2012"/><ref name="Dominissini_2012"/> and transcriptome-wide analysis reveals that m⁶A is found in regions of high evolutionary conservation.<ref name="Meyer_2012"/> m⁶A is found within long internal exons and is preferentially enriched within 3' UTRs and around stop codons. m⁶A within 3' UTRs is also associated with the presence of microRNA binding sites; roughly 2/3 of the mRNAs which contain an m⁶A site within their 3' UTR also have at least one microRNA binding site.<ref name="Meyer_2012"/> By integrating all m⁶A sequencing data, a novel database called RMBase has identified and provided ~200,000 sites in the human and mouse genomes corresponding to N6-Methyladenosines (m⁶A) in RNA.<ref name="Sun_2016"/>

Precise m6A mapping by m6A-CLIP/IP <ref name="ke2015">{{cite journal | vauthors = Ke S, Alemu EA, Mertens C, Gantman EC, Fak JJ, Mele A, Haripal B, Zucker-Scharff I, Moore MJ, Park CY, Vågbø CB, Kusśnierczyk A, Klungland A, Darnell JE, Darnell RB | display-authors = 6 | title = A majority of m6A residues are in the last exons, allowing the potential for 3' UTR regulation | journal = Genes & Development | volume = 29 | issue = 19 | pages = 2037–2053 | date = October 2015 | pmid = 26404942 | pmc = 4604345 | doi = 10.1101/gad.269415.115 }}</ref> (briefly m6A-CLIP) revealed that a majority of m6A locates in the last exon of mRNAs in multiple tissues/cultured cells of mouse and human,<ref name="ke2015"/> and the m6A enrichment around stop codons is a coincidence that many stop codons locate round the start of last exons where m6A is truly enriched.<ref name="ke2015"/> The major presence of m6A in last exon (>=70%) allows the potential for 3'UTR regulation, including alternative polyadenylation.<ref name="ke2015"/> The study combining m6A-CLIP with rigorous cell fractionation biochemistry reveals that m6A mRNA modifications are deposited in nascent pre-mRNA and are not required for splicing but do specify cytoplasmic turnover.<ref name="ke2017">{{cite journal | vauthors = Ke S, Pandya-Jones A, Saito Y, Fak JJ, Vågbø CB, Geula S, Hanna JH, Black DL, Darnell JE, Darnell RB | display-authors = 6 | title = m⁶A mRNA modifications are deposited in nascent pre-mRNA and are not required for splicing but do specify cytoplasmic turnover | journal = Genes & Development | volume = 31 | issue = 10 | pages = 990–1006 | date = May 2017 | pmid = 28637692 | pmc = 5495127 | doi = 10.1101/gad.301036.117 }}</ref><ref name="Rosa-Mercado2017">{{cite journal | vauthors = Rosa-Mercado NA, Withers JB, Steitz JA | title = Settling the m⁶A debate: methylation of mature mRNA is not dynamic but accelerates turnover | journal = Genes & Development | volume = 31 | issue = 10 | pages = 957–958 | date = May 2017 | pmid = 28637691 | pmc = 5495124 | doi = 10.1101/gad.302695.117 }}</ref>

m⁶A is susceptible to dynamic regulation both throughout development and in response to cellular stimuli. Analysis of m⁶A in mouse brain RNA reveals that m⁶A levels are low during embryonic development and increase dramatically by adulthood.<ref name="Meyer_2012"/> In mESCs and during mouse development, FTO has been shown to mediated LINE1 RNA m⁶A demethylation and consequently affect local chromatin state and nearby gene transcription.<ref>{{cite journal | vauthors = Wei J, Yu X, Yang L, Liu X, Gao B, Huang B, Dou X, Liu J, Zou Z, Cui XL, Zhang LS, Zhao X, Liu Q, He PC, Sepich-Poore C, Zhong N, Liu W, Li Y, Kou X, Zhao Y, Wu Y, Cheng X, Chen C, An Y, Dong X, Wang H, Shu Q, Hao Z, Duan T, He YY, Li X, Gao S, Gao Y, He C | display-authors = 6 | title = FTO mediates LINE1 m⁶A demethylation and chromatin regulation in mESCs and mouse development | journal = Science | volume = 376 | issue = 6596 | pages = 968–973 | date = May 2022 | pmid = 35511947 | pmc = 9746489 | doi = 10.1126/science.abe9582 | bibcode = 2022Sci...376..968W }}</ref> Additionally, silencing the m⁶A methyltransferase significantly affects gene expression and alternative RNA splicing patterns, resulting in modulation of the p53 (also known as TP53) signalling pathway and apoptosis.<ref name="Dominissini_2012"/>

m⁶A is also found on the RNA components of R-loops in human and plant cells, where it is involved in regulation of stability of RNA:DNA hybrids. It has been reported to modulate R-loop levels with different outcomes (R-loop resolution and stabilization).<ref>{{cite journal | vauthors = Abakir A, Giles TC, Cristini A, Foster JM, Dai N, Starczak M, Rubio-Roldan A, Li M, Eleftheriou M, Crutchley J, Flatt L, Young L, Gaffney DJ, Denning C, Dalhus B, Emes RD, Gackowski D, Corrêa IR, Garcia-Perez JL, Klungland A, Gromak N, Ruzov A | display-authors = 6 | title = N⁶-methyladenosine regulates the stability of RNA:DNA hybrids in human cells | journal = Nature Genetics | volume = 52 | issue = 1 | pages = 48–55 | date = January 2020 | pmid = 31844323 | pmc = 6974403 | doi = 10.1038/s41588-019-0549-x }}</ref><ref>Abakir, A., Ruzov, A. A model for a dual function of N6-methyladenosine in R-loop regulation. Nat Genet (2024). https://doi.org/10.1038/s41588-024-01905-5</ref>

The importance of m⁶A methylation for physiological processes was recently demonstrated. Inhibition of m⁶A methylation via pharmacological inhibition of cellular methylations or more specifically by siRNA-mediated silencing of the m⁶A methylase ''Mettl3'' led to the elongation of the circadian period. In contrast, overexpression of ''Mettl3'' led to a shorter period. The mammalian circadian clock, composed of a transcription feedback loop tightly regulated to oscillate with a period of about 24 hours, is therefore extremely sensitive to perturbations in m⁶A-dependent RNA processing, likely due to the presence of m⁶A sites within clock gene transcripts.<ref name="Fustin">{{cite journal | vauthors = Fustin JM, Doi M, Yamaguchi Y, Hida H, Nishimura S, Yoshida M, Isagawa T, Morioka MS, Kakeya H, Manabe I, Okamura H | display-authors = 6 | title = RNA-methylation-dependent RNA processing controls the speed of the circadian clock | journal = Cell | volume = 155 | issue = 4 | pages = 793–806 | date = November 2013 | pmid = 24209618 | doi = 10.1016/j.cell.2013.10.026 | doi-access = free }}</ref><ref name="Hastings">{{cite journal | vauthors = Hastings MH | title = m(6)A mRNA methylation: a new circadian pacesetter | journal = Cell | volume = 155 | issue = 4 | pages = 740–741 | date = November 2013 | pmid = 24209613 | doi = 10.1016/j.cell.2013.10.028 | doi-access = free }}</ref> The effects of global methylation inhibition on the circadian period in mouse cells can be prevented by ectopic expression of an enzyme from the bacterial methyl metabolism. Mouse cells expressing this bacterial protein were resistant to pharmacological inhibition of methyl metabolism, showing no decrease in mRNA m⁶A methylation or protein methylation.<ref name=Fustin2>{{cite journal | vauthors = Fustin JM, Ye S, Rakers C, Kaneko K, Fukumoto K, Yamano M, Versteven M, Grünewald E, Cargill SJ, Tamai TK, Xu Y, Jabbur ML, Kojima R, Lamberti ML, Yoshioka-Kobayashi K, Whitmore D, Tammam S, Howell PL, Kageyama R, Matsuo T, Stanewsky R, Golombek DA, Johnson CH, Kakeya H, van Ooijen G, Okamura H | display-authors = 6 | title = Methylation deficiency disrupts biological rhythms from bacteria to humans | journal = Communications Biology | volume = 3 | issue = 1 | page = 211 | date = May 2020 | pmid = 32376902 | pmc = 7203018 | doi = 10.1038/s42003-020-0942-0 | doi-access = free }}</ref>

==== In development ==== m⁶A modifications, along with other epigenetic changes, have been shown to play important roles during eukaryotic development. Hematopoietic Stem Cells (HSCs), Neuronal Stem Cells (NSCs) and Primordial Germ Cells (PCGs) have all been shown to undergo m⁶A modifications during growth and differentiation. Depending on the stage of development, modifications to HSCs can either promote or inhibit stem cell differentiation by affecting the epithelial-to-hemopoietic transition via METTL3 inhibition or depletion. m⁶A modifications to NSCs can causes changes in brain size, neuron formation, long-term memory, and learning ability. These changes are often caused by inhibition of either METTL or YTHDF readers and writers. In the reproductive system, m⁶A modifications have been shown to disrupt the maternal-to-zygotic mRNA transition and negatively affect both gamete formation and fertility. Similar to NSCs, inhibition of the METTL and YTHDF families of proteins is often a catalyst for these changes.<ref>{{Cite journal |last1=Jiang |first1=Xiulin |last2=Liu |first2=Baiyang |last3=Nie |first3=Zhi |last4=Duan |first4=Lincan |last5=Xiong |first5=Qiuxia |last6=Jin |first6=Zhixian |last7=Yang |first7=Cuiping |last8=Chen |first8=Yongbin |date=2021-02-21 |title=The role of m6A modification in the biological functions and diseases |journal=Signal Transduction and Targeted Therapy |volume=6 |issue=1 |page=74 |doi=10.1038/s41392-020-00450-x |issn=2059-3635 |pmc=7897327 |pmid=33611339}}</ref> m⁶A is also required for proper axonal development by regulating the transport and local translation of actin mRNAs in neurons, and its disruption leads to impaired axon growth.<ref>{{cite journal |last1=Shohayeb |first1=B. |last2=Sempert |first2=K. |last3=Lanoue |first3=V. |last4=O’Brien |first4=E.A. |last5=Flores |first5=C. |last6=Cooper |first6=H.M. |title=m6A-dependent regulation of actin mRNA transport controls axonal development |journal=Cell Reports |year=2025 |volume= |issue= |pages= |doi= |url=https://www.cell.com/cell-reports/fulltext/S2211-1247(25)00498-X }}</ref>

== Clinical significance ==

Considering the versatile functions of m⁶A in various physiological processes, it is thus not surprising to find links between m⁶A and numerous human diseases; many originated from mutations or single nucleotide polymorphisms (SNPs) of cognate factors of m⁶A. The linkages between m⁶A and numerous cancer types have been indicated in reports that include stomach cancer, prostate cancer, breast cancer, pancreatic cancer, kidney cancer, mesothelioma, sarcoma, and leukaemia.<ref>{{cite journal | vauthors = Akilzhanova A, Nurkina Z, Momynaliev K, Ramanculov E, Zhumadilov Z, Rakhypbekov T, Hayashida N, Nakashima M, Takamura N | display-authors = 6 | title = Genetic profile and determinants of homocysteine levels in Kazakhstan patients with breast cancer | journal = Anticancer Research | volume = 33 | issue = 9 | pages = 4049–4059 | date = September 2013 | pmid = 24023349 }}</ref><ref>{{cite journal | vauthors = Reddy SM, Sadim M, Li J, Yi N, Agarwal S, Mantzoros CS, Kaklamani VG | title = Clinical and genetic predictors of weight gain in patients diagnosed with breast cancer | journal = British Journal of Cancer | volume = 109 | issue = 4 | pages = 872–881 | date = August 2013 | pmid = 23922112 | pmc = 3749587 | doi = 10.1038/bjc.2013.441 }}</ref><ref>{{cite journal | vauthors = Heiliger KJ, Hess J, Vitagliano D, Salerno P, Braselmann H, Salvatore G, Ugolini C, Summerer I, Bogdanova T, Unger K, Thomas G, Santoro M, Zitzelsberger H | display-authors = 6 | title = Novel candidate genes of thyroid tumourigenesis identified in Trk-T1 transgenic mice | journal = Endocrine-Related Cancer | volume = 19 | issue = 3 | pages = 409–421 | date = June 2012 | pmid = 22454401 | doi = 10.1530/ERC-11-0387 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Ortega A, Niksic M, Bachi A, Wilm M, Sánchez L, Hastie N, Valcárcel J | title = Biochemical function of female-lethal (2)D/Wilms' tumor suppressor-1-associated proteins in alternative pre-mRNA splicing | journal = The Journal of Biological Chemistry | volume = 278 | issue = 5 | pages = 3040–3047 | date = January 2003 | pmid = 12444081 | doi = 10.1074/jbc.M210737200 | doi-access = free | hdl = 10261/162976 | hdl-access = free }}</ref><ref>{{cite journal | vauthors = Jin DI, Lee SW, Han ME, Kim HJ, Seo SA, Hur GY, Jung S, Kim BS, Oh SO | display-authors = 6 | title = Expression and roles of Wilms' tumor 1-associating protein in glioblastoma | journal = Cancer Science | volume = 103 | issue = 12 | pages = 2102–2109 | date = December 2012 | pmid = 22957919 | pmc = 7659328 | doi = 10.1111/cas.12022 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Lin Y, Ueda J, Yagyu K, Ishii H, Ueno M, Egawa N, Nakao H, Mori M, Matsuo K, Kikuchi S | display-authors = 6 | title = Association between variations in the fat mass and obesity-associated gene and pancreatic cancer risk: a case-control study in Japan | journal = BMC Cancer | volume = 13 | page = 337 | date = July 2013 | pmid = 23835106 | pmc = 3716552 | doi = 10.1186/1471-2407-13-337 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Casalegno-Garduño R, Schmitt A, Wang X, Xu X, Schmitt M | title = Wilms' tumor 1 as a novel target for immunotherapy of leukemia | journal = Transplantation Proceedings | volume = 42 | issue = 8 | pages = 3309–3311 | date = October 2010 | pmid = 20970678 | doi = 10.1016/j.transproceed.2010.07.034 }}</ref><ref>{{cite journal | vauthors = Linnebacher M, Wienck A, Boeck I, Klar E | title = Identification of an MSI-H tumor-specific cytotoxic T cell epitope generated by the (-1) frame of U79260(FTO) | journal = Journal of Biomedicine & Biotechnology | volume = 2010 | article-number = 841451 | date = 2010-03-18 | pmid = 20339516 | pmc = 2842904 | doi = 10.1155/2010/841451 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Machiela MJ, Lindström S, Allen NE, Haiman CA, Albanes D, Barricarte A, Berndt SI, Bueno-de-Mesquita HB, Chanock S, Gaziano JM, Gapstur SM, Giovannucci E, Henderson BE, Jacobs EJ, Kolonel LN, Krogh V, Ma J, Stampfer MJ, Stevens VL, Stram DO, Tjønneland A, Travis R, Willett WC, Hunter DJ, Le Marchand L, Kraft P | display-authors = 6 | title = Association of type 2 diabetes susceptibility variants with advanced prostate cancer risk in the Breast and Prostate Cancer Cohort Consortium | journal = American Journal of Epidemiology | volume = 176 | issue = 12 | pages = 1121–1129 | date = December 2012 | pmid = 23193118 | pmc = 3571230 | doi = 10.1093/aje/kws191 }}</ref><ref>{{cite journal | vauthors = Long J, Zhang B, Signorello LB, Cai Q, Deming-Halverson S, Shrubsole MJ, Sanderson M, Dennis J, Michailidou K, Easton DF, Shu XO, Blot WJ, Zheng W | display-authors = 6 | title = Evaluating genome-wide association study-identified breast cancer risk variants in African-American women | journal = PLOS ONE | volume = 8 | issue = 4 | article-number = e58350 | date = 2013-04-08 | pmid = 23593120 | pmc = 3620157 | doi = 10.1371/journal.pone.0058350 | doi-access = free | bibcode = 2013PLoSO...858350L }}</ref><ref>{{cite journal | vauthors = Kaklamani V, Yi N, Sadim M, Siziopikou K, Zhang K, Xu Y, Tofilon S, Agarwal S, Pasche B, Mantzoros C | display-authors = 6 | title = The role of the fat mass and obesity associated gene (FTO) in breast cancer risk | journal = BMC Medical Genetics | volume = 12 | page = 52 | date = April 2011 | pmid = 21489227 | pmc = 3089782 | doi = 10.1186/1471-2350-12-52 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Pierce BL, Austin MA, Ahsan H | title = Association study of type 2 diabetes genetic susceptibility variants and risk of pancreatic cancer: an analysis of PanScan-I data | journal = Cancer Causes & Control | volume = 22 | issue = 6 | pages = 877–883 | date = June 2011 | pmid = 21445555 | pmc = 7043136 | doi = 10.1007/s10552-011-9760-5 }}</ref> The impacts of m⁶A on cancer cell proliferation might be much more profound with more data emerging. The depletion of METTL3 is known to cause apoptosis of cancer cells and reduce invasiveness of cancer cells,<ref>{{Cite book|title=Fine-Tuning of RNA Functions by Modification and Editing|volume = 12| vauthors = Bokar JA |date=2005-01-01|publisher=Springer Berlin Heidelberg|isbn=978-3-540-24495-0| veditors = Grosjean H |series=Topics in Current Genetics|pages=141–177 |doi=10.1007/b106365|chapter = The biosynthesis and functional roles of methylated nucleosides in eukaryotic mRNA}}</ref><ref>{{cite journal | vauthors = Lin S, Choe J, Du P, Triboulet R, Gregory RI | title = The m(6)A Methyltransferase METTL3 Promotes Translation in Human Cancer Cells | journal = Molecular Cell | volume = 62 | issue = 3 | pages = 335–345 | date = May 2016 | pmid = 27117702 | pmc = 4860043 | doi = 10.1016/j.molcel.2016.03.021 }}</ref> while the activation of ALKBH5 by hypoxia was shown to cause cancer stem cell enrichment.<ref>{{cite journal | vauthors = Zhang C, Samanta D, Lu H, Bullen JW, Zhang H, Chen I, He X, Semenza GL | display-authors = 6 | title = Hypoxia induces the breast cancer stem cell phenotype by HIF-dependent and ALKBH5-mediated m⁶A-demethylation of NANOG mRNA | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 113 | issue = 14 | pages = E2047–E2056 | date = April 2016 | pmid = 27001847 | pmc = 4833258 | doi = 10.1073/pnas.1602883113 | doi-access = free | bibcode = 2016PNAS..113E2047Z }}</ref> m⁶A has also been indicated in the regulation of energy homeostasis and obesity, as FTO is a key regulatory gene for energy metabolism and obesity. SNPs of ''FTO'' have been shown to associate with body mass index in human populations and occurrence of obesity and diabetes.<ref>{{cite journal | vauthors = Loos RJ, Yeo GS | title = The bigger picture of FTO: the first GWAS-identified obesity gene | journal = Nature Reviews. Endocrinology | volume = 10 | issue = 1 | pages = 51–61 | date = January 2014 | pmid = 24247219 | pmc = 4188449 | doi = 10.1038/nrendo.2013.227 }}</ref><ref>{{cite journal | vauthors = Frayling TM, Timpson NJ, Weedon MN, Zeggini E, Freathy RM, Lindgren CM, Perry JR, Elliott KS, Lango H, Rayner NW, Shields B, Harries LW, Barrett JC, Ellard S, Groves CJ, Knight B, Patch AM, Ness AR, Ebrahim S, Lawlor DA, Ring SM, Ben-Shlomo Y, Jarvelin MR, Sovio U, Bennett AJ, Melzer D, Ferrucci L, Loos RJ, Barroso I, Wareham NJ, Karpe F, Owen KR, Cardon LR, Walker M, Hitman GA, Palmer CN, Doney AS, Morris AD, Smith GD, Hattersley AT, McCarthy MI | display-authors = 6 | title = A common variant in the FTO gene is associated with body mass index and predisposes to childhood and adult obesity | journal = Science | volume = 316 | issue = 5826 | pages = 889–894 | date = May 2007 | pmid = 17434869 | pmc = 2646098 | doi = 10.1126/science.1141634 | bibcode = 2007Sci...316..889F }}</ref><ref>{{cite journal | vauthors = Wang L, Yu Q, Xiong Y, Liu L, Zhang X, Zhang Z, Wu J, Wang B | display-authors = 6 | title = Variant rs1421085 in the FTO gene contribute childhood obesity in Chinese children aged 3-6 years | journal = Obesity Research & Clinical Practice | volume = 7 | issue = 1 | pages = e14–e22 | year = 2013 | pmid = 24331679 | doi = 10.1016/j.orcp.2011.12.007 }}</ref><ref>{{cite journal | vauthors = Kalnina I, Zaharenko L, Vaivade I, Rovite V, Nikitina-Zake L, Peculis R, Fridmanis D, Geldnere K, Jacobsson JA, Almen MS, Pirags V, Schiöth HB, Klovins J | display-authors = 6 | title = Polymorphisms in FTO and near TMEM18 associate with type 2 diabetes and predispose to younger age at diagnosis of diabetes | journal = Gene | volume = 527 | issue = 2 | pages = 462–468 | date = September 2013 | pmid = 23860325 | doi = 10.1016/j.gene.2013.06.079 }}</ref><ref>{{cite journal | vauthors = Karra E, O'Daly OG, Choudhury AI, Yousseif A, Millership S, Neary MT, Scott WR, Chandarana K, Manning S, Hess ME, Iwakura H, Akamizu T, Millet Q, Gelegen C, Drew ME, Rahman S, Emmanuel JJ, Williams SC, Rüther UU, Brüning JC, Withers DJ, Zelaya FO, Batterham RL | display-authors = 6 | title = A link between FTO, ghrelin, and impaired brain food-cue responsivity | journal = The Journal of Clinical Investigation | volume = 123 | issue = 8 | pages = 3539–3551 | date = August 2013 | pmid = 23867619 | pmc = 3726147 | doi = 10.1172/jci44403 }}</ref> The influence of FTO on pre-adipocyte differentiation has been suggested.<ref>{{cite journal | vauthors = Zhao X, Yang Y, Sun BF, Shi Y, Yang X, Xiao W, Hao YJ, Ping XL, Chen YS, Wang WJ, Jin KX, Wang X, Huang CM, Fu Y, Ge XM, Song SH, Jeong HS, Yanagisawa H, Niu Y, Jia GF, Wu W, Tong WM, Okamoto A, He C, Rendtlew Danielsen JM, Wang XJ, Yang YG | display-authors = 6 | title = FTO-dependent demethylation of N6-methyladenosine regulates mRNA splicing and is required for adipogenesis | journal = Cell Research | volume = 24 | issue = 12 | pages = 1403–1419 | date = December 2014 | pmid = 25412662 | pmc = 4260349 | doi = 10.1038/cr.2014.151 }}</ref><ref>{{cite journal | vauthors = Merkestein M, Laber S, McMurray F, Andrew D, Sachse G, Sanderson J, Li M, Usher S, Sellayah D, Ashcroft FM, Cox RD | display-authors = 6 | title = FTO influences adipogenesis by regulating mitotic clonal expansion | journal = Nature Communications | volume = 6 | page = 6792 | date = April 2015 | pmid = 25881961 | pmc = 4410642 | doi = 10.1038/ncomms7792 | bibcode = 2015NatCo...6.6792M }}</ref><ref>{{cite journal | vauthors = Zhang M, Zhang Y, Ma J, Guo F, Cao Q, Zhang Y, Zhou B, Chai J, Zhao W, Zhao R | display-authors = 6 | title = The Demethylase Activity of FTO (Fat Mass and Obesity Associated Protein) Is Required for Preadipocyte Differentiation | journal = PLOS ONE | volume = 10 | issue = 7 | article-number = e0133788 | date = 2015-07-28 | pmid = 26218273 | pmc = 4517749 | doi = 10.1371/journal.pone.0133788 | doi-access = free | bibcode = 2015PLoSO..1033788Z }}</ref> The connection between m⁶A and neuronal disorders has also been studied. For instance, neurodegenerative diseases may be affected by m⁶A as the cognate dopamine signalling was shown to be dependent on FTO and correct m⁶A methylation on key signalling transcripts.<ref>{{cite journal | vauthors = Hess ME, Hess S, Meyer KD, Verhagen LA, Koch L, Brönneke HS, Dietrich MO, Jordan SD, Saletore Y, Elemento O, Belgardt BF, Franz T, Horvath TL, Rüther U, Jaffrey SR, Kloppenburg P, Brüning JC | display-authors = 6 | title = The fat mass and obesity associated gene (Fto) regulates activity of the dopaminergic midbrain circuitry | journal = Nature Neuroscience | volume = 16 | issue = 8 | pages = 1042–1048 | date = August 2013 | pmid = 23817550 | doi = 10.1038/nn.3449 | s2cid = 11452560 }}</ref> The mutations in HNRNPA2B1, a potential reader of m⁶A, have been known to cause neurodegeneration.<ref>{{cite journal | vauthors = Kim HJ, Kim NC, Wang YD, Scarborough EA, Moore J, Diaz Z, MacLea KS, Freibaum B, Li S, Molliex A, Kanagaraj AP, Carter R, Boylan KB, Wojtas AM, Rademakers R, Pinkus JL, Greenberg SA, Trojanowski JQ, Traynor BJ, Smith BN, Topp S, Gkazi AS, Miller J, Shaw CE, Kottlors M, Kirschner J, Pestronk A, Li YR, Ford AF, Gitler AD, Benatar M, King OD, Kimonis VE, Ross ED, Weihl CC, Shorter J, Taylor JP | display-authors = 6 | title = Mutations in prion-like domains in hnRNPA2B1 and hnRNPA1 cause multisystem proteinopathy and ALS | journal = Nature | volume = 495 | issue = 7442 | pages = 467–473 | date = March 2013 | pmid = 23455423 | pmc = 3756911 | doi = 10.1038/nature11922 | bibcode = 2013Natur.495..467K }}</ref> The IGF2BP1–3, a novel class of m⁶A reader, has oncogenic functions. IGF2BP1–3 knockdown or knockout decreased MYC protein expression, cell proliferation and colony formation in human cancer cell lines.<ref name = "Huang_2018" /> The ZC3H13, a member of the m6A methyltransferase complex, markedly inhibited colorectal cancer cells growth when knocked down.<ref>{{cite journal | vauthors = Wang ZL, Li B, Luo YX, Lin Q, Liu SR, Zhang XQ, Zhou H, Yang JH, Qu LH | display-authors = 6 | title = Comprehensive Genomic Characterization of RNA-Binding Proteins across Human Cancers | journal = Cell Reports | volume = 22 | issue = 1 | pages = 286–298 | date = January 2018 | pmid = 29298429 | doi = 10.1016/j.celrep.2017.12.035 | doi-access = free }}</ref>

Additionally, m⁶A has been reported to impact viral infections. Many RNA viruses including SV40, adenovirus, herpes virus, Rous sarcoma virus, and influenza virus have been known to contain internal m⁶A methylation on virus genomic RNA.<ref name="pmid1315118">{{cite book | vauthors = Narayan P, Rottman FM | title = Advances in Enzymology and Related Areas of Molecular Biology | chapter = Methylation of mRNA | series = Advances in Enzymology - and Related Areas of Molecular Biology | volume = 65 | pages = 255–285 | date = 1992 | pmid = 1315118 | doi = 10.1002/9780470123119.ch7 | isbn = 978-0-470-12311-9 | veditors = Nord FF }}</ref> Several more recent studies have revealed that m⁶A regulators govern the efficiency of infection, replication, translation and transport of RNA viruses such as human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV), and Zika virus (ZIKV).<ref>{{cite journal | vauthors = Kennedy EM, Bogerd HP, Kornepati AV, Kang D, Ghoshal D, Marshall JB, Poling BC, Tsai K, Gokhale NS, Horner SM, Cullen BR | display-authors = 6 | title = Posttranscriptional m(6)A Editing of HIV-1 mRNAs Enhances Viral Gene Expression | journal = Cell Host & Microbe | volume = 19 | issue = 5 | pages = 675–685 | date = May 2016 | pmid = 27117054 | pmc = 4867121 | doi = 10.1016/j.chom.2016.04.002 }}</ref><ref>{{cite journal | vauthors = Tirumuru N, Zhao BS, Lu W, Lu Z, He C, Wu L | title = N(6)-methyladenosine of HIV-1 RNA regulates viral infection and HIV-1 Gag protein expression | journal = eLife | volume = 5 | date = July 2016 | pmid = 27371828 | pmc = 4961459 | doi = 10.7554/eLife.15528 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Lichinchi G, Gao S, Saletore Y, Gonzalez GM, Bansal V, Wang Y, Mason CE, Rana TM | display-authors = 6 | title = Dynamics of the human and viral m(6)A RNA methylomes during HIV-1 infection of T cells | journal = Nature Microbiology | volume = 1 | issue = 4 | page = 16011 | date = February 2016 | pmid = 27572442 | pmc = 6053355 | doi = 10.1038/nmicrobiol.2016.11 }}</ref><ref>{{cite journal | vauthors = Lichinchi G, Zhao BS, Wu Y, Lu Z, Qin Y, He C, Rana TM | title = Dynamics of Human and Viral RNA Methylation during Zika Virus Infection | journal = Cell Host & Microbe | volume = 20 | issue = 5 | pages = 666–673 | date = November 2016 | pmid = 27773536 | pmc = 5155635 | doi = 10.1016/j.chom.2016.10.002 }}</ref><ref>{{cite journal | vauthors = Gokhale NS, McIntyre AB, McFadden MJ, Roder AE, Kennedy EM, Gandara JA, Hopcraft SE, Quicke KM, Vazquez C, Willer J, Ilkayeva OR, Law BA, Holley CL, Garcia-Blanco MA, Evans MJ, Suthar MS, Bradrick SS, Mason CE, Horner SM | display-authors = 6 | title = N6-Methyladenosine in Flaviviridae Viral RNA Genomes Regulates Infection | journal = Cell Host & Microbe | volume = 20 | issue = 5 | pages = 654–665 | date = November 2016 | pmid = 27773535 | pmc = 5123813 | doi = 10.1016/j.chom.2016.09.015 }}</ref><ref name=":1">{{Cite journal |last1=Moon |first1=Jae-Su |last2=Lee |first2=Wooseong |last3=Cho |first3=Yong-Hee |last4=Kim |first4=Yonghyo |last5=Kim |first5=Geon-Woo |date=2024-02-28 |title=The Significance of N6-Methyladenosine RNA Methylation in Regulating the Hepatitis B Virus Life Cycle |journal=Journal of Microbiology and Biotechnology |volume=34 |issue=2 |pages=233–239 |doi=10.4014/jmb.2309.09013 |issn=1738-8872 |pmid=37942519|pmc=10940779 }}</ref> These results suggest m⁶A and its cognate factors play crucial roles in regulating virus life cycles and host-viral interactions.

Aside from affecting viruses themselves, m⁶A modifications can also disrupt the innate immune response. For example, in HBV, m⁶A modifications were shown to disrupt the recognition of viruses by RIG-1, a pattern recognition receptor in the immune system. Modifications can also disrupt downstream signaling pathways via mechanisms including ubiquitination and changes in the levels of protein expression.<ref name=":1" />

== In bacteria == M6A methylation is also widespread in bacteria, influencing functions such as DNA replication, repair, and gene expression, and prokaryotic defense.

In replication, M6A modifications mark DNA regions where the initiation stage takes place as well as regulates precise timing via the Dam methyltransferase in E. coli.<ref>{{Citation |last1=O'Brown |first1=Zach Klapholz |title=N6-Methyladenine: A Conserved and Dynamic DNA Mark |date=2016 |work=DNA Methyltransferases - Role and Function |pages=213–246 |editor-last=Jeltsch |editor-first=Albert |place=Cham |publisher=Springer International Publishing |language=en |doi=10.1007/978-3-319-43624-1_10 |isbn=978-3-319-43624-1 |pmc=5291743 |pmid=27826841 |last2=Greer |first2=Eric Lieberman |volume=945 |editor2-last=Jurkowska |editor2-first=Renata Z.}}</ref><ref>{{Cite journal |last1=Balzarolo |first1=Melania |last2=Engels |first2=Sander |last3=de Jong |first3=Anja J. |last4=Franke |first4=Katka |last5=van den Berg |first5=Timo K. |last6=Gulen |first6=Muhammet F. |last7=Ablasser |first7=Andrea |last8=Janssen |first8=Edith M. |last9=van Steensel |first9=Bas |last10=Wolkers |first10=Monika C. |date=March 2021 |title=m6A methylation potentiates cytosolic dsDNA recognition in a sequence-specific manner |journal=Open Biology |language=en |volume=11 |issue=3 |doi=10.1098/rsob.210030 |doi-access=free|issn=2046-2441 |pmc=8101014 |pmid=33715389}}</ref> Another enzyme, Dam DNA methylase regulates mismatch repair using M6A modifications which influence other repair proteins by recognizing specific mismatches.<ref>{{Cite journal |url=https://academic.oup.com/nar/article/47/11/5698/5430841 |access-date=2024-04-07 |doi=10.1093/nar/gkz242 |pmc=6582345 |pmid=30957852 |title=A new role for Escherichia coli Dam DNA methylase in prevention of aberrant chromosomal replication |date=2019 |last1=Raghunathan |first1=Nalini |last2=Goswami |first2=Sayantan |last3=Leela |first3=Jakku K. |last4=Pandiyan |first4=Apuratha |last5=Gowrishankar |first5=Jayaraman |journal=Nucleic Acids Research |volume=47 |issue=11 |pages=5698–5711 }}</ref>

In some cases of DNA protection, M6A methylations (along with M4C modifications) play a role in the protection of bacterial DNA by influencing certain endonucleases via the restriction-modification system, decreasing the influence of bacteriophages. One such role is introducing a methyltransferase which recognizes the same target site that restriction enzymes (Type 1 restriction enzymes) attack and modifying it in order to stop such enzymes from attacking bacteria DNA.<ref>{{Cite journal |last1=Blow |first1=Matthew J. |last2=Clark |first2=Tyson A. |last3=Daum |first3=Chris G. |last4=Deutschbauer |first4=Adam M. |last5=Fomenkov |first5=Alexey |last6=Fries |first6=Roxanne |last7=Froula |first7=Jeff |last8=Kang |first8=Dongwan D. |last9=Malmstrom |first9=Rex R. |last10=Morgan |first10=Richard D. |last11=Posfai |first11=Janos |last12=Singh |first12=Kanwar |last13=Visel |first13=Axel |last14=Wetmore |first14=Kelly |last15=Zhao |first15=Zhiying |date=2016-02-12 |title=The Epigenomic Landscape of Prokaryotes |journal=PLOS Genetics |language=en |volume=12 |issue=2 |article-number=e1005854 |doi=10.1371/journal.pgen.1005854 |doi-access=free |issn=1553-7404 |pmc=4752239 |pmid=26870957}}</ref><ref>{{Cite journal |last1=Loenen |first1=W. A. M. |last2=Dryden |first2=D. T. F. |last3=Raleigh |first3=E. A. |last4=Wilson |first4=G. G. |date=2014-01-01 |title=Type I restriction enzymes and their relatives |journal=Nucleic Acids Research |language=en |volume=42 |issue=1 |pages=20–44 |doi=10.1093/nar/gkt847 |issn=0305-1048 |pmc=3874165 |pmid=24068554}}</ref>

== References == {{Reflist|33em}} {{Nucleobases, nucleosides, and nucleotides}}

{{DEFAULTSORT:Methyladenosine, N6-}} Category:Nucleosides Category:Purines Category:Hydroxymethyl compounds