Project description:In mammals, the acquisition of the germline from the soma provides the germline with an essential challenge, the necessity to erase and reset genomic methylation. In the male germline RNA-directed DNA methylation silences young active transposable elements (TEs). The PIWI protein MIWI2 (PIWIL4) and its associated PIWI-interacting RNAs (piRNAs) are proposed to tether MIWI2 to nascent TE transcripts and instruct DNA methylation. The mechanism by which MIWI2 directs de novo TE methylation is poorly understood but central to the immortality of the germline. Here, we define the interactome of MIWI2 in foetal gonocytes that are undergoing de novo genome methylation and identify a novel MIWI2-associated factor, SPOCD1, that is essential for young TE methylation and silencing. The loss of Spocd1 in mice results in male specific infertility and does not impact on piRNA biogenesis nor localization of MIWI2 to the nucleus. SPOCD1 is a nuclear protein and its expression is restricted to the period of de novo genome methylation. We found SPOCD1 co-purified in vivo with DNMT3L and DNMT3A, components of the de novo methylation machinery as well as constituents of the NURD and BAF chromatin remodelling complexes. We propose a model whereby tethering of MIWI2 to a nascent TE transcript recruits repressive chromatin remodelling activities and the de novo methylation apparatus through its association with SPOCD1. In summary, we have identified a novel and essential executor of mammalian piRNA-directed DNA methylation.
Project description:In mammals, the acquisition of the germline from the soma provides the germline with an essential challenge, the necessity to erase and reset genomic methylation. In the male germline RNA-directed DNA methylation silences young active transposable elements (TEs). The PIWI protein MIWI2 (PIWIL4) and its associated PIWI-interacting RNAs (piRNAs) are proposed to tether MIWI2 to nascent TE transcripts and instruct DNA methylation. The mechanism by which MIWI2 directs de novo TE methylation is poorly understood but central to the immortality of the germline. Here, we define the interactome of MIWI2 in foetal gonocytes that are undergoing de novo genome methylation and identify a novel MIWI2-associated factor, SPOCD1, that is essential for young TE methylation and silencing. The loss of Spocd1 in mice results in male specific infertility and does not impact on piRNA biogenesis nor localization of MIWI2 to the nucleus. SPOCD1 is a nuclear protein and its expression is restricted to the period of de novo genome methylation. We found SPOCD1 co-purified in vivo with DNMT3L and DNMT3A, components of the de novo methylation machinery as well as constituents of the NURD and BAF chromatin remodelling complexes. We propose a model whereby tethering of MIWI2 to a nascent TE transcript recruits repressive chromatin remodelling activities and the de novo methylation apparatus through its association with SPOCD1. In summary, we have identified a novel and essential executor of mammalian piRNA-directed DNA methylation.
Project description:Oocyte acquires developmental competence during its maturation. This stage is accompanied with large-scale alteration in transcription, and series of genome-wide epigenetic reprogramming, including de novo establishment of DNA methylation. However, our understanding of mechanisms regulating this process is limited. To investigate the role of Stella (Dppa3) in de novo methylation during mouse oogenesis, here we measured DNA methylation by RRBS and expression profiles by RNA-seq in PGCs and oocytes at serveral development stages, including genotypes of both Stella (Dppa3) +/- and Stella -/-.
Project description:Post-mitotic neurons exhibit DNA methylation changes, contrary to the longstanding belief that the epigenetic pattern in terminally differentiated cells is essentially unchanging. While the mechanism and physiological significance of DNA demethylation in neurons have been extensively elucidated, occurrence of de novo DNA methylation and its impacts have been much less investigated. Here we show that neuronal activation induces global de novo DNA methylation at enhancer regions that can repress target genes in primary cultured hippocampal neurons. The functional significance of this de novo DNA methylation was underpinned by the demonstration that inhibition of DNA methyltransferase (DNMT) activity decreased neuronal activity-induced excitatory synaptogenesis. Overexpression of WW and C2 Domain containing 1 (Wwc1), a representative target gene of de novo DNA methylation, could phenocopy this DNMT inhibition-induced decrease in the synaptogenesis. We found that both DNMT1 and DNMT3a were required for the neuronal activity-induced de novo DNA methylation of Wwc1 enhancer. Taking these findings altogether, we concluded that activity-induced de novo DNA methylation affecting gene expression has impacts on neuronal physiology comparable to those of DNA demethylation.
Project description:Numerous adult diseases involving tissues that consist primarily of non-dividing cells are associated with changes in DNA methylation. It suggests a role for de novo methylation or demethylation of DNA, which is catalyzed by DNA methyltransferase 3 (Dnmt3) and ten-eleven translocases (Tet). However, the contribution of DNA de novo (de)methylation to these diseases remains nearly completely unproven. Broad changes in DNA methylation occurred within days in the renal outer medulla of Dahl SS rats fed a high-salt diet, a classic model of hypertension. Intra-renal administration of anti-Dnmt3a/Tet3 GapmeR’s attenuated high salt-induced hypertension in SS rats. The high salt diet induced differential expression of 1,712 genes in the renal outer medulla. Remarkably, the differential expression of 76% of these genes were prevented by anti-Dnmt3a/Tet3 GapmeR’s. The genes differentially expressed in response to the GapmeR’s were involved in the regulation of metabolism and inflammation and were significantly enriched for genes showing differential methylation in response to the GapmeR’s. These data indicate DNA de novo (de)methylation in the kidney contributes to the development of hypertension in SS rats. The findings should help to shift the paradigm of DNA methylation research in diseases involving non-dividing cells from correlative analysis to functional and mechanistic studies.
Project description:Numerous adult diseases involving tissues that consist primarily of non-dividing cells are associated with changes in DNA methylation. It suggests a role for de novo methylation or demethylation of DNA, which is catalyzed by DNA methyltransferase 3 (Dnmt3) and ten-eleven translocases (Tet). However, the contribution of DNA de novo (de)methylation to these diseases remains nearly completely unproven. Broad changes in DNA methylation occurred within days in the renal outer medulla of Dahl SS rats fed a high-salt diet, a classic model of hypertension. Intra-renal administration of anti-Dnmt3a/Tet3 GapmeR’s attenuated high salt-induced hypertension in SS rats. The high salt diet induced differential expression of 1,712 genes in the renal outer medulla. Remarkably, the differential expression of 76% of these genes were prevented by anti-Dnmt3a/Tet3 GapmeR’s. The genes differentially expressed in response to the GapmeR’s were involved in the regulation of metabolism and inflammation and were significantly enriched for genes showing differential methylation in response to the GapmeR’s. These data indicate DNA de novo (de)methylation in the kidney contributes to the development of hypertension in SS rats. The findings should help to shift the paradigm of DNA methylation research in diseases involving non-dividing cells from correlative analysis to functional and mechanistic studies.
Project description:Mammalian de novo DNA methyltransferases (DNMT) are responsible for the establishment of cell-type-specific DNA methylation in healthy and diseased tissues. Through genome-wide analysis of de novo methylation activity in murine stem cells we uncover that DNMT3A prefers to methylate CpGs followed by cytosines or thymines, while DNMT3B predominantly methylates CpGs followed by guanines or adenines. These signatures are further observed at non-CpG sites, resembling methylation context observed in specialised cell types, including neurons and oocytes. We further show that these preferences result from structural differences in the catalytic domains of the two de novo DNMTs and are not a consequence of differential recruitment to the genome. Molecular dynamics simulations suggest that, in case of human DNMT3A, the preference is due to favourable polar interactions between the flexible Arg836 side chain and the guanine that base-pairs with the cytosine following the CpG. By exchanging arginine to a lysine, the corresponding sidechain in DNMT3B, the sequence preference is reversed, confirming the requirement for arginine at this position. This context-dependent de novo DNA methylation by DNMT3A and DNMT3B, provides additional insights into the complex regulation of methylation patterns.
Project description:An increasing body of work reveals aberrant hypermethylation of genes occurring in and potentially contributing to the pathogenesis of myeloid malignancies. Several of these diseases, such as myelodysplastic syndromes (MDS), are responsive to DNA methyltransferase inhibitors. In order to determine the extent of promoter hypermethylation in such tumors we compared the distribution of DNA methylation of 14,000 promoters in MDS and secondary AML patients enrolled in a phase I trial of 5-azacytidine and the histone deacetylase inhibitor entinostat against de novo AML patients and normal CD34+ bone marrow cells. The MDS and secondary AML patients displayed more extensive aberrant DNA methylation involving thousands of genes than did the normal CD34+ bone marrow cells or de novo AML blasts. Aberrant methylation in MDS and secondary AML tended to affect particular chromosomal regions, occurred more frequently in Alu poor genes, and included prominent involvement of genes involved in the WNT and MAPK signaling pathways. DNA methylation was also measured at days 15 and 29 after the first treatment cycle. DNA methylation was reversed at day 15 in a uniform manner throughout the genome, and this effect persisted through day 29, even without continuous administration of the study drugs. Keywords: DNA methylation profiling Direct comparison of DNA methylation in bone marrow samples from patients with Myelodysplastic syndrome or secondary Acute Myeloid Leukemia (AML) at baseline and after in vivo treatment with 5-azacytidine + etinostat. A comparison to de novo normal karyotype AML was also performed. Two control groups were included: one consisting of 8 CD34+ bone marrow samples from healthy donors and a second one consisting of matched CD34+ and CD34- fractions from the bone marrows of 4 healthy donors.