Regulation of DNA methylation by CK2-mediated phosphorylation of DNMT3A (Beadchip)
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ABSTRACT: DNA methylation is a central epigenetic modification that has essential roles in cellular processes including chromatin structure, gene regulation, development and disease. The de novo DNA methyltransferases are responsible for the generation of genomic methylation patterns, but the underlying mechanisms are still poorly understood. Here, we show that phosphorylation of DNMT3A by the CK2 protein kinase regulates the establishment of DNA methylation patterns. We find that DNMT3A is phosphorylated by CK2 at two key residues located near its PWWP domain. We observed that, through phosphorylation of these residues, CK2 negatively regulates DNMT3A’s ability to methylate DNA and consistent with this, CK2 was found to decrease overall genomic level of 5-methylcytosine. Further, genome-wide DNA methylation analysis in CK2-depleted cells revealed that CK2 affects primarily CpG methylation of several heterochromatin repeats as well as Alu elements. Along these lines, we found that CK2-mediated phosphorylation of DNMT3A was required for its proper heterochromatin localization. Our results define phosphorylation as a new mode of regulation of de novo DNA methyltransferase function. These findings further uncover a previously unrecognized mechanism for the regulation of methylation at repetitive elements. They shed new light into the origin of DNA methylation patterns.
Project description:DNA methylation is a central epigenetic modification that has essential roles in cellular processes including chromatin structure, gene regulation, development and disease. The de novo DNA methyltransferases are responsible for the generation of genomic methylation patterns, but the underlying mechanisms are still poorly understood. Here, we show that phosphorylation of DNMT3A by the CK2 protein kinase regulates the establishment of DNA methylation patterns. We find that DNMT3A is phosphorylated by CK2 at two key residues located near its PWWP domain. We observed that, through phosphorylation of these residues, CK2 negatively regulates DNMT3AM-bM-^@M-^Ys ability to methylate DNA and consistent with this, CK2 was found to decrease overall genomic level of 5-methylcytosine. Further, genome-wide DNA methylation analysis in CK2-depleted cells revealed that CK2 affects primarily CpG methylation of several heterochromatin repeats as well as Alu elements. Along these lines, we found that CK2-mediated phosphorylation of DNMT3A was required for its proper heterochromatin localization. Our results define phosphorylation as a new mode of regulation of de novo DNA methyltransferase function. These findings further uncover a previously unrecognized mechanism for the regulation of methylation at repetitive elements. They shed new light into the origin of DNA methylation patterns. Bisulphite converted DNA from 6 samples were hybridised to the Illumina Infinium 27K Human Methylation Beadchip v1.2
Project description:DNA methylation is a central epigenetic modification that has essential roles in cellular processes including chromatin structure, gene regulation, development and disease. The de novo DNA methyltransferases are responsible for the generation of genomic methylation patterns, but the underlying mechanisms are still poorly understood. Here, we show that phosphorylation of DNMT3A by the CK2 protein kinase regulates the establishment of DNA methylation patterns. We find that DNMT3A is phosphorylated by CK2 at two key residues located near its PWWP domain. We observed that, through phosphorylation of these residues, CK2 negatively regulates DNMT3A’s ability to methylate DNA and consistent with this, CK2 was found to decrease overall genomic level of 5-methylcytosine. Further, genome-wide DNA methylation analysis in CK2-depleted cells revealed that CK2 affects primarily CpG methylation of several heterochromatin repeats as well as Alu elements. Along these lines, we found that CK2-mediated phosphorylation of DNMT3A was required for its proper heterochromatin localization. Our results define phosphorylation as a new mode of regulation of de novo DNA methyltransferase function. These findings further uncover a previously unrecognized mechanism for the regulation of methylation at repetitive elements. They shed new light into the origin of DNA methylation patterns.
Project description:DNA methyltransferase 3A (DNMT3A) plays a critical role in establishing and maintaining DNA methylation patterns. However, the mechanisms underlying DNMT3A recruitment to and function within different chromatin environments remain unclear. Using a combination of biochemical and structural approaches we find that DNMT3A interacts using multiple interfaces with chromatin; directly binding generic nucleosome features as well as site-specific post-translational histone modifications. The N-terminal region, unique to the DNMT3A1 isoform, is essential for these interactions and stabilises H3K36me2-nucleosome recruitment. Intriguingly, in the same region critical for nucleosome binding we also map a ubiquitylation-dependent recruitment motif (UDR). The UDR binds specifically to ubiquitylated H2AK119, explaining the previously observed recruitment to Polycomb-occupied heterochromatin. A cryo-EM structure of DNMT3A1-DNMT3L with a modified nucleosome reveals that the UDR interacts with the nucleosome surface including the acidic patch. Previously unexplained disease-associated mutations are present in the UDR and ablate nucleosome interactions. This leads to an increased understanding of how DNMT3A1 recruitment occurs in the genome and highlights the importance of multivalent binding of DNMT3A to histone modifications and the nucleosome.
Project description:Protein Ser/Thr kinase CK2 is involved in a myriad of cellular processes including cell growth and proliferation by phosphorylating hundreds of substrates, yet the regulation process of CK2 function is poorly understood. The CK2 catalytic subunit, CK2α, is phosphorylated at Thr344 and phosphorylation on the C-terminal tail of CK2α is required for interaction with Pin1 protein. The substrate selectivity for protein kinase CK2α was examined by performing kinase assays on protein microarrays spotted with 17,000 human proteins. Semisynthetic CK2α proteins were prepared to contain an unmodified C-terminal tail or phospho-Thr (pThr) at T344. These semisynthetic proteins were used to determine if the phosphorylation-dependent interaction of CK2α with Pin1 can modulate the substrate selectivity for CK2. The different semisynthetic CK2α proteins (unmodified and pThr344) were tested alone and in the presence of the recombinant Pin1 protein. Pin1 has been shown to interaction with CK2α only when CK2α is phoshorylated on its C-terminal site (including Thr344).
Project description:Protein Ser/Thr kinase CK2 is involved in a myriad of cellular processes including cell growth and proliferation by phosphorylating hundreds of substrates, yet the regulation process of CK2 function is poorly understood. The CK2 catalytic subunit, CK2α, is phosphorylated at Thr344 and phosphorylation on the C-terminal tail of CK2α is required for interaction with Pin1 protein. The substrate selectivity for protein kinase CK2α was examined by performing kinase assays on protein microarrays spotted with 17,000 human proteins. Semisynthetic CK2α proteins were prepared to contain an unmodified C-terminal tail or phospho-Thr (pThr) at T344. These semisynthetic proteins were used to determine if the phosphorylation-dependent interaction of CK2α with Pin1 can modulate the substrate selectivity for CK2. The different semisynthetic CK2α proteins (unmodified and pThr344) were tested alone and in the presence of the recombinant Pin1 protein. Pin1 has been shown to interaction with CK2α only when CK2α is phoshorylated on its C-terminal site (including Thr344). In the study presented here, kinase assays were performed using two different semisynthetic CK2α proteins: unmodified C-terminal tail and phospho-Thr (pThr) at 344. The semisynthetic proteins were each tested alone and in the presence of the recombinant Pin1 protein. There were four different kinase conditions and each condition was performed in duplicate.
Project description:We investigated influence of CMTR1 phosphorylation by CK2 on RNA expression. In this experiment, we added wild-type and phosphorylation deficient mutant of CMTR1 and knocked out the endogenous CMTR1. We demonstrated that lack of phosphorylation of CMTR1 affects only small but specific group of genes.
Project description:mRNA translation plays a major role in homeostasis, whereas its dysregulation underpins a variety of pathological states including cancer, metabolic syndrome and neurological disorders. Ternary complex (TC) and eIF4F complex assembly are two major rate-limiting steps in translation initiation that are thought to be regulated by eIF2α phosphorylation, and the mTOR/4E-BP pathway, respectively2. However, how TC and eIF4F assembly are coordinated remains largely unknown. Using polysome-profiling, we show that on a genome-wide scale mTOR suppresses translation of mRNAs, which are translationally activated under short-term ER stress when TC recycling is attenuated by eIF2α phosphorylation. During acute nutrient or growth factor stimulation, mTORC1 induces eIF2β phosphorylation, which increases recruitment of NCK1 to eIF2, decreases eIF2α phosphorylation and bolsters TC recycling. Accordingly, eIF2β appears to act as a previously unidentified mediator of mTORC1 on protein synthesis and proliferation. In addition, we demonstrate a formerly undocumented role for CK2 in regulation of translation initiation, whereby CK2 stimulates phosphorylation of eIF2β and simultaneously bolsters eIF4F complex assembly via the mTORC1/4E-BP pathway. These findings imply a previously unrecognized mode of translation regulation whereby mTORC1 and CK2 coordinate TC and eIF4F complex assembly to stimulate cell proliferation.
Project description:The DNA methylation program is at the bottom layer of the epigenetic regulatory cascade of vertebrate development. While the methylation at C-5 position of the cytosine (C) residues on the vertebrate genomes is achieved through the catalytic activities of the DNA methyltransferases (DNMTs), the conversion of the methylated cytosine (5mC) could be accomplished by the combined actions of the TET enzyme and DNA repair. Interestingly, it has been found recently that the mouse and human DNMTs also possess active DNA demethylation activity in vitro in a Ca2+- and redox condition-dependent manner. We report here the study of tracking down the fate of the methyl group removed from 5mC on DNA during in vitro demethylation reaction by mouse de novo DNMTs, i.e. DNMT3A and DNMT3B. Remarkably, the methyl group becomes covalently linked to the catalytic cysteines utilized by the two de novo DNMTs in their DNA methylation reactions. Thus, the forward and reverse reactions of DNA methylations by the DNMTs may utilize the same cysteine residue(s) as the active site despite of their distinctive pathways. Secondly, we demonstrate that active DNA demethylation of a heavily methylated GFP reporter plasmid by ectopically expressed DNMT3A or DNMT3B occurs in vivo in transfected human HEK 293 cells in culture. Furthermore, the extent of DNA demethylation by the DNMTs in this cell-based system is affected by Ca2+ homeostasis as well as by mutation of their putative active cysteines. These findings substantiate the roles of the vertebrate DNMTs as double-edged swords in DNA methylation-demethylation in vitro as well as in a cellular context.