Project description:DNA methylation generally functions as a repressive transcriptional signal, but it is also known to activate gene expression. In either case, the downstream factors remain largely unknown. By using comparative interactomics, we isolated proteins in Arabidopsis thaliana that associate with methylated DNA. Two SU(VAR)3-9 homologs, the transcriptional antisilencing factor SUVH1, and SUVH3, were among the methyl reader candidates. SUVH1 and SUVH3 bound methylated DNA in vitro, were associated with euchromatic methylation in vivo, and formed a complex with two DNAJ domain-containing homologs, DNAJ1 and DNAJ2. Ectopic recruitment of DNAJ1 enhanced gene transcription in plants, yeast, and mammals. Thus, the SUVH proteins bind to methylated DNA and recruit the DNAJ proteins to enhance proximal gene expression, thereby counteracting the repressive effects of transposon insertion near genes.
Project description:BRD4 functions as an epigenetic reader and plays a crucial role in regulating transcription and genome stability. Dysregulation of BRD4 is frequently observed in various human cancers. However, the molecular details of BRD4 regulation remain largely unknown. Here, we report that PRMT2- and PRMT4-mediated arginine methylation is pivotal for BRD4-dependent transcription, DNA repair, and tumor growth. Specifically, PRMT2/4 interact with and methylates BRD4 at R179, R181, and R183. This arginine methylation selectively controls a transcriptional program by promoting BRD4 enrichment at the hyper-acetylated chromatin regions. Moreover, BRD4 arginine methylation is induced by DNA damage and thereby promotes its binding to chromatin for DNA repair. Deficiency in BRD4 arginine methylation significantly suppresses tumor growth and sensitizes cells to BET inhibitors and DNA damaging agents. Therefore, our findings reveal an arginine methylation-dependent regulatory mechanism of BRD4 function and highlight targeting PRMT2/4 for better anti-tumor effect of BET inhibitors and DNA damaging agents.
Project description:The N6-methyladenosine (m6A) is the most abundant internal modification in almost all eukaryotic messenger RNAs, and is dynamically regulated. Therefore, identification of m6A readers is especially important in determining the cellular function of m6A. YTHDF2 has recently been characterized as the first m6A reader that regulates the cytoplasmic stability of methylated RNA. Here we show that YTHDC1 is a nuclear m6A reader and report the crystal structure of the YTH domain of YTHDC1 bound to m6A-containing RNA. We further determined the structure of another YTH domain, YTHDF1, and found that the YTH domain utilizes a conserved aromatic cage to specifically recognize the methyl group of m6A. Our structural characterizations of the YTHDC1-m6A RNA complex also shed light on the molecular basis for the preferential binding of the GG(m6A)C sequence by YTHDC1 and confirm the YTH domain as a specific m6A RNA reader. PAR-CLIP (Photoactivatable-Ribonucleoside-Enhanced Crosslinking and Immunoprecipitation) was applied to human YTHDC1 protein to identify its binding sites.
Project description:Mammalian DNA (cytosine-5) methyltransferase 1 (DNMT1) is essential for maintenance methylation. Phosphorylation of Ser143 (pSer143) stabilizes DNMT1 during DNA replication. Here, we show 14-3-3 is a reader protein of DNMT1pSer143. In mammalian cells 14-3-3 colocalizes and binds DNMT1pSer143 post-DNA replication. The level of DNMT1pSer143 increased with overexpression of 14-3-3 and decreased by its depletion. Binding of 14-3-3 proteins with DNMT1pSer143 resulted in inhibition of DNA methylation activity in vitro. In addition, overexpression of 14-3-3 in NIH3T3 cells led to decrease in DNMT1 specific activity and was rescued by transfection of DNMT1. Decrease in DNMT1 specific activity led to hypomethylation of the genome. Genes representing cell migration, mobility, proliferation and focal adhesion pathway were hypomethylated and overexpressed. Furthermore, 14-3-3 overexpression also resulted in enhanced cell invasion. Therefore, we suggest that 14-3-3 is a crucial reader of DNMT1pSer143 that regulates DNMT1 level, DNA methylation and altered gene expression that contributes to cell invasion. Examine of the DNA methylation and RNA expression profiles of stable NIH3T3 clones overexressing the 14-3-3ε homologue
Project description:We report a DNA templated chemistry and photo-crosslinking based method to detect the readers of mRNA modification. By use of N6-methyladenosine (m6A), we illustrated that this method can be successfully utilized for labelling and enriching the readers of mRNA modification, as well as for the discovery of new partners. Thus we applied this strategy to a new modification 2'-O-methyladenosine. As a result, DDX1 was identified and verified as a potential reader by in vitro and in vivo experiments. Our study therefore provides a powerful chemical proteomics tool for identifying the readers of mRNA modification and reveals the underlying function of mRNA modification.
Project description:In this study, we investigated the dynamics during differentiation of the in vivo binding sites of ZBTB2, a putative reader for unmethylated DNA. We performed DNA pull-downs followed by mass spectrometry, using a genomic sequence containing either unmethylated or methylated CpGs, to study the influence of DNA methylation on ZBTB2 binding. Additionally, we performed interaction proteomics to identify ZBTB2 interaction partners. We found that ZBTB2 recruits a zinc finger module of three proteins to unmethylated DNA.