Project description:Here we determine the map of RNA methylation (m6A) in mouse embrionic stem cells, and Mettl3 knock out cells Examination of m6A modification sites on the transcriptome of mouse Embryonic stem cells and Embryonic Mettl3 knock out cells, using a m6A specific antibody.
Project description:N6-methyladenosine (m6A) is the most prevalent internal modification found in mammalian messenger and non-coding RNAs. The discoveries of functionally significant demethylases that reverse this methylation as well as the recently revealed m6A distributions in mammalian transcriptomes strongly indicate regulatory functions of this modification. Here we report the identification and characterization of the mammalian nuclear RNA N6-adenosine methyltransferase core (RNMTC) complex. Besides METTL3, a methyltransferase which was the only known component of RNMTC in the past, we discovered that a previously uncharacterized methyltransferase, METTL14, exhibits a N6-adenosine methyltransferase activity higher than METTL3. Together with WTAP, the third component that dramatically affects the cellular m6A level, these three proteins form the core complex that orchestrates m6A deposition on mammalian nuclear RNA. Biochemistry assays, imaging experiments, as well as transcriptome-wide analyses of the binding sites and their effects on m6A methylation support methylation function and reveal new insights of RNMTC. PAR-CLIP and m6A-seq in HeLa cells
Project description:N6-methyl-adenosine (m6A) is the most abundant modification on messenger RNAs and is linked to human diseases, but its functions in mammalian development are poorly understood. Here we reveal the evolutionary conservation and function of m6A by mapping the m6A methylome in mouse and human embryonic stem cells. Thousands of messenger and long noncoding RNAs show conserved m6A modification, including transcripts encoding core pluripotency transcription factors. m6A is enriched over 3M-bM-^@M-^Y untranslated regions at defined sequence motifs, and marks unstable transcripts, including transcripts turned over upon differentiation. Genetic inactivation or depletion of mouse and human Mettl3, one of the m6A methylases, led to m6A erasure on select target genes, prolonged Nanog expression upon differentiation, and impaired ESCM-bM-^@M-^Ys exit from self-renewal towards differentiation into several lineages in vitro and in vivo. Thus, m6A is a mark of transcriptome flexibility required for stem cells to differentiate to specific lineages. Examing m6A modification differences in two different cell types
Project description:Recent methylome studies have located N6-methyladenosine (m6A) RNA modification on thousands of mammalian transcripts. However, its functional mechanism remains unclear. In this study, we examined the role of m6A methylation in mouse embryonic stem cells. To gain an understanding of dynamic changes in cells depleted with (proposed) methyltranferases at molecular level, we examined the time-series gene expression pattern in mESC lines using microarray analysis.
Project description:Stem cells balance cellular fates through asymmetric and symmetric divisions in order to self-renew or to generate downstream progenitors. Symmetric commitment divisions in stem cells are required for rapid regeneration during tissue damage and stress. The control of symmetric commitment remains poorly defined. N6-methyladenosine (m6A), the most abundant posttranscriptional mRNA modification controls cellular states and its abundance is dysregulated in cancer. Here we show that mRNA methylation controls symmetric commitment and cell identity of hematopoietic stem cells (HSCs). Using single-cell RNA sequencing (scRNA-seq) in combination with transcriptomic profiling of HSPCs (hematopoietic stem and progenitor cells) from control and m6A methyltransferase Mettl3 conditional knockout mice, we found that m6A-deficient HSC fail to symmetrically differentiate. Dividing HSCs are expanded and are blocked in an intermediate state that molecularly and functionally resembles multipotent progenitors. Mechanistically, RNA methylation controls Myc mRNA abundance in differentiating HSCs. Importantly, we identified MYC as a new marker for HSC asymmetric and symmetric commitment. Furthermore, forced expression of MYC rescued m6A’s requirement for engraftment indicating its importance in the early stage of HSC cellular fate. Overall our results indicate that RNA methylation is critical for normal blood homeostasis and may provide a general mechanism for how stem cells regulate differentiation fate choice.
Project description:m6A is the most abundant modification of mRNA in mammals and plays an important role in human development and disease. METTL14 is a key component of m6A methyltransferase complex. The project showed that its post-translational arginine methylation can regulate the generation of m6A and the endoderm differentiation of mouse embryonic stem cells, indicating its essential function in the normal development of embryos.
Project description:Recent methylome studies have located N6-methyladenosine (m6A) RNA modification on thousands of mammalian transcripts. However, its functional mechanism remains unclear. In this study, we examined the role of m6A methylation in mouse embryonic stem cells. To gain an understanding of dynamic changes in cells depleted with (proposed) methyltranferases at molecular level, we examined the time-series gene expression pattern in mESC lines using microarray analysis. After 0, 4 and 8 h incubation with scramble, shRNA for Mettl3 or Mettl14, mESC cells were collected and RNAs were isolated for microarray analysis using Affymetrix Genechip Mouse Gene 2.0 ST array. After 0 h incubation with scramble, shRNA for Mettl3 or Mettl14, mESC cells were collected and RNAs were isolated for microarray analysis using Affymetrix Genechip Mouse Gene 2.0 ST array.