(2016) m6A potentiates Sxl alternative pre-mRNA splicing for robust Drosophila sex determination. Nature, 540 (7632). pp. 301-304. ISSN 1476-4687 Access from the University of Nottingham repository: http://eprints.nottingham.ac.uk/39448/1/Nature_m6A_2016.pdf Copyright and reuse:The Nottingham ePrints service makes this work by researchers of the University of Nottingham available open access under the following conditions. This article is made available under the University of Nottingham End User licence and may be reused according to the conditions of the licence. For more details see: http://eprints.nottingham.ac.uk/end_user_agreement.pdf A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. sex bias towards maleness. This is because m6A is required for female-specific AS of Sxl, 37 which determines female physiognomy, but also translationally represses male-specific 38 lethal2 (msl-2) to prevent dosage compensation normally occurring in males. We further 39show that the m6A reader protein YT521-B decodes m6A in the sex-specifically spliced 40 intron of Sxl, as its absence phenocopies dIME4 mutants. Loss of m6A also affects AS of 41 additional genes, predominantly in the 5'UTR, and has global impacts on the expression of 42 metabolic genes. Requirement of m6A and its reader YT521-B for female-specific Sxl AS 43 reveal that this hitherto enigmatic mRNA modification constitutes an ancient and specific 44 mechanism to adjust levels of gene expression. 45In mature mRNA the m6A modification is most prevalently found around the stop codon as well 46 as in 5'UTRs and in long exons in mammals, plants and yeast 2,3,6,7,15 . Since methylosome 47 components predominantly localize to the nucleus it has been speculated that m6A localized in 48Haussmann et al.3 pre-mRNA introns could have a role in AS regulation in addition to such a role when present in 49 long exons [9][10][11][12]16 . This prompted us to investigate whether m6A is required for Sxl AS, which 50 determines female sex and prevents dosage compensation in females 13 . We generated a null 51 allele of the Drosophila METTL3 methyltransferase homologue dIME4 by imprecise excision of 52 a P-element inserted in the promoter region. The excision ∆22-3 deletes most of the protein-53 coding region including the catalytic domain and is thus referred to as dIME4 null (Fig 1a). These 54 flies are viable and fertile, but flightless, and this phenotype can be rescued by a genomic 55 construct restoring dIME4 (Fig 1a and b). dIME4 shows increased expression in the brain, and 56 like in mammals and plants 17, localizes to the nucleus (Fig 1c,d). 57Following RNAse T1 digestion and 32 P end-labeling of RNA fragments we detected m6A after G 58 in polyA mRNA of adult flies at relatively low l...

A major constraint on the evolution of large body sizes in animals is an increased risk of developing cancer. There is no correlation, however, between body size and cancer risk. This lack of correlation is often referred to as 'Peto's Paradox'. Here, we show that the elephant genome encodes 20 copies of the tumor suppressor gene TP53 and that the increase in TP53 copy number occurred coincident with the evolution of large body sizes, the evolution of extreme sensitivity to genotoxic stress, and a hyperactive TP53 signaling pathway in the elephant (Proboscidean) lineage. Furthermore, we show that several of the TP53 retrogenes (TP53RTGs) are transcribed and likely translated. While TP53RTGs do not appear to directly function as transcription factors, they do contribute to the enhanced sensitivity of elephant cells to DNA damage and the induction of apoptosis by regulating activity of the TP53 signaling pathway. These results suggest that an increase in the copy number of TP53 may have played a direct role in the evolution of very large body sizes and the resolution of Peto's paradox in Proboscideans.DOI: http://dx.doi.org/10.7554/eLife.11994.001

Coordinated transcription factor networks have emerged as the master regulatory mechanisms of stem cell pluripotency and differentiation. Many stem cell-specifi c transcription factors, including the pluripotency transcription factors, OCT4, NANOG, and SOX2 function in combinatorial complexes to regulate the expression of loci, which are involved in embryonic stem (ES) cell pluripotency and cellular differentiation. This review will address how these pathways form a reciprocal regulatory circuit whereby the equilibrium between stem cell self-renewal, proliferation, and differentiation is in perpetual balance. We will discuss how distinct epigenetic repressive pathways involving polycomb complexes, DNA methylation, and microRNAs cooperate to reduce transcriptional noise and to prevent stochastic and aberrant induction of differentiation. We will provide a brief overview of how these networks cooperate to modulate differentiation along hematopoietic and neuronal lineages. Finally, we will describe how aberrant functioning of components of the stem cell regulatory network may contribute to malignant transformation of adult stem cells and the establishment of a "cancer stem cell" phenotype and thereby underlie multiple types of human malignancies.

Summary N6‐adenosine methylation (m6A) of mRNA is an essential process in most eukaryotes, but its role and the status of factors accompanying this modification are still poorly understood.Using combined methods of genetics, proteomics and RNA biochemistry, we identified a core set of mRNA m6A writer proteins in Arabidopsis thaliana.The components required for m6A in Arabidopsis included MTA, MTB, FIP37, VIRILIZER and the E3 ubiquitin ligase HAKAI. Downregulation of these proteins led to reduced relative m6A levels and shared pleiotropic phenotypes, which included aberrant vascular formation in the root, indicating that correct m6A methylation plays a role in developmental decisions during pattern formation.The conservation of these proteins amongst eukaryotes and the demonstration of a role in writing m6A for the E3 ubiquitin ligase HAKAI is likely to be of considerable relevance beyond the plant sciences.