scholarly journals Acute depletion of METTL3 identifies a role for N6-methyladenosine in alternative intron/exon inclusion in the nascent transcriptome

2020 ◽  
Author(s):  
Guifeng Wei ◽  
Mafalda Almeida ◽  
Greta Pintacuda ◽  
Heather Coker ◽  
Joseph S Bowness ◽  
...  

AbstractRNA N6-methyladenosine (m6A) modification plays important roles in multiple aspects of RNA regulation. m6A is installed co-transcriptionally by the METTL3/14 complex, but its direct roles in RNA processing remain unclear. Here we investigate the presence of m6A in nascent RNA of mouse embryonic stem cells (mESCs). We find that around 10% m6A peaks are in introns, often close to 5’-splice sites. RNA m6A peaks significantly overlap with RBM15 RNA binding sites and the histone modification H3K36me3. Interestingly, acute dTAG depletion of METTL3 reveals that inclusion of m6A-bearing alternative introns/exons in the nascent transcriptome is disrupted. For terminal or variable-length exons, m6A peaks are generally located upstream of a repressed 5’-splice site, and downstream of an enhanced 5’-splice site. Intriguingly, genes with the most immediate effects on splicing include several components of the m6A pathway, suggesting an autoregulatory function. Our findings demonstrate a direct crosstalk between m6A machinery and the regulation of RNA processing.

2021 ◽  
Author(s):  
Sungwook Han ◽  
Hosuk Lee ◽  
Andrew J. Lee ◽  
Seung-Kyoon Kim ◽  
Inkyung Jung ◽  
...  

CTCF plays a critical role in the 3D chromatin organization by determining the TAD borders. Although CTCF primarily binds at the TAD borders, there also exist putative CTCF-binding sites within TADs, which are spread throughout the genome by retrotransposition. However, the detailed mechanism responsible for masking these putative CTCF-binding sites remains elusive. Here, we show that the ATP-dependent chromatin remodeler, CHD4, regulates chromatin accessibility to conceal aberrant CTCF-binding sites embedded in H3K9me3-enriched heterochromatic B2 SINEs in mouse embryonic stem cells (mESCs). Upon CHD4 depletion, these aberrant CTCF-binding sites become accessible, and aberrant CTCF recruitment occurs at the TAD interiors, resulting in disorganization of the local TADs. Furthermore, RNA-binding intrinsically disordered domains of CHD4 is required to prevent the aberrant CTCF bindings. Lastly, CHD4 is required for the repression of B2 SINE transcripts. These results highlight the CHD4-mediated mechanism that safeguards the appropriate CTCF bindings and associated TAD organizations in mESCs.


Cell Reports ◽  
2021 ◽  
Vol 35 (9) ◽  
pp. 109198
Author(s):  
Shlomi Dvir ◽  
Amir Argoetti ◽  
Chen Lesnik ◽  
Mark Roytblat ◽  
Kohava Shriki ◽  
...  

2019 ◽  
Author(s):  
Isabelle Leticia Zaboroski Silva ◽  
Anny Waloski Robert ◽  
Guillermo Cabrera Cabo ◽  
Lucia Spangenberg ◽  
Marco Augusto Stimamiglio ◽  
...  

AbstractPosttranscriptional regulation plays a fundamental role in the biology of embryonic stem cells (ESCs). Many studies have demonstrated that multiple mRNAs are coregulated by one or more RNA binding proteins (RBPs) that orchestrate the expression of these molecules. A family of RBPs, known as PUF (Pumilio-FBF), is highly conserved among species and has been associated with the undifferentiated and differentiated states of different cell lines. In humans, two homologs of the PUF family have been found: Pumilio 1 (PUM1) and Pumilio 2 (PUM2). To understand the role of these proteins in human ESCs (hESCs), we first demonstrated the influence of the silencing of PUM1 and PUM2 on pluripotency genes. OCT4 and NANOG mRNA levels decreased significantly with the knockdown of Pumilio, suggesting that PUMILIO proteins play a role in the maintenance of pluripotency in hESCs. Furthermore, we observed that the hESCs silenced for PUM1 and 2 exhibited an improvement in efficiency of in vitro cardiomyogenic differentiation. Using in silico analysis, we identified mRNA targets of PUM1 and PUM2 expressed during cardiomyogenesis. With the reduction of PUM1 and 2, these target mRNAs would be active and could be involved in the progression of cardiomyogenesis.


2018 ◽  
Vol 32 (07) ◽  
pp. 1850075
Author(s):  
Rongsheng Huang ◽  
Jinzhi Lei

Experiments have shown that in embryonic stem cells, the promoters of many lineage-control genes contain “bivalent domains”, within which the nucleosomes possess both active (H3K4me3) and repressive (H3K27me3) marks. Such bivalent modifications play important roles in maintaining pluripotency in embryonic stem cells. Here, to investigate gene expression dynamics when there are regulations in bivalent histone modifications and random partition in cell divisions, we study how positive feedback to histone methylation/demethylation controls the transition dynamics of the histone modification patterns along with cell cycles. We constructed a computational model that includes dynamics of histone marks, three-stage chromatin state transitions, transcription and translation, feedbacks from protein product to enzymes to regulate the addition and removal of histone marks, and the inheritance of nucleosome state between cell cycles. The model reveals how dynamics of both nucleosome state transition and gene expression are dependent on the enzyme activities and feedback regulations. Results show that the combination of stochastic histone modification at each cell division and the deterministic feedback regulation work together to adjust the dynamics of chromatin state transition in stem cell regenerations.


2012 ◽  
Vol 9 (2) ◽  
pp. 88-100 ◽  
Author(s):  
Yuriy Orlov ◽  
Han Xu ◽  
Dmitri Afonnikov ◽  
Bing Lim ◽  
Jian-Chien Heng ◽  
...  

Summary Advances in high throughput sequencing technology have enabled the identification of transcription factor (TF) binding sites in genome scale. TF binding studies are important for medical applications and stem cell research. Somatic cells can be reprogrammed to a pluripotent state by the combined introduction of factors such as Oct4, Sox2, c-Myc, Klf4. These reprogrammed cells share many characteristics with embryonic stem cells (ESCs) and are known as induced pluripotent stem cells (iPSCs). The signaling requirements for maintenance of human and murine embryonic stem cells (ESCs) differ considerably. Genome wide ChIP-seq TF binding maps in mouse stem cells include Oct4, Sox2, Nanog, Tbx3, Smad2 as well as group of other factors. ChIP-seq allows study of new candidate transcription factors for reprogramming. It was shown that Nr5a2 could replace Oct4 for reprogramming. Epigenetic modifications play important role in regulation of gene expression adding additional complexity to transcription network functioning. We have studied associations between different histone modification using published data together with RNA Pol II sites. We found strong associations between activation marks and TF binding sites and present it qualitatively. To meet issues of statistical analysis of genome ChIP-sequencing maps we developed computer program to filter out noise signals and find significant association between binding site affinity and number of sequence reads. The data provide new insights into the function of chromatin organization and regulation in stem cells.


2011 ◽  
Vol 18 (2) ◽  
pp. 237-244 ◽  
Author(s):  
Anthony K L Leung ◽  
Amanda G Young ◽  
Arjun Bhutkar ◽  
Grace X Zheng ◽  
Andrew D Bosson ◽  
...  

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