Nsun2 Mediates M5c Rna Methylation To Control Gene Regulatory Functions For Maintaining The Self-renewal Of Murine Embryonic Stem Cells State
NSUN2 mediates m5C RNA methylation to control gene regulatory functions for maintaining the self-renewal of murine embryonic stem cells state Michael Bullen, Yogesh Kumar, Pratibha Tripathi and Partha Das Epitranscriptomic or RNA epigenetic modifications take place at the post-transcriptional level in transcribed RNAs without altering any RNA sequences. Over 150 different types of RNA modifications have been identified in diverse classes of RNA in various organisms. However, recent advancement in high throughput sequencing technology has been able to map a few of these modifications, including 5-methylcytosine (m5C) transcriptome-wide, enabling the understanding of the molecular and biological functions of these RNA modifications. The m5C RNA methylation is catalysed by m5C-writers/methyltransferases (TRDMT1 and NSUN1-7) in various types of RNA, mostly in tRNA, rRNA and mitochondrial RNA, and a small number of mRNA. Putative m5C-erasers/demethylases (TETs) reverses this modification, while ALYREF is the only m5C-reader discovered so far that recognises m5C. To date, no studies have reported the roles of m5C in embryonic stem cells (ESCs). Thus, in my PhD study, I focus on investigating the roles of NSUN2 (the best-studied m5C methyltransferase) in murine ESCs (mESCs). To analyse the functions of NSUN2-mediated m5C RNA methylation in mESCs, we generated Nsun2 KO mESCs, which displayed a self-renewal defect. Subsequent molecular analyses determined NSUN2 mediates m5C RNA methylation predominantly in tRNA and mRNA, including several critical mESC-specific transcripts. Moreover, we demonstrated that NSUN2 regulates the deposition of m5C in mRNAs co-transcriptionally. The current investigation is underway to examine whether and how m5C RNA methylation controls tRNA and mRNA fates to define the self-renewal defects in Nsun2 KO. I anticipate this study will dissect the detailed molecular functions of NSUN2-mediated m5C RNA methylation in gene regulatory functions that are critical for maintaining the mESC state for the first time.