Project description:Reconstruction of ancient epigenomes by DNA methylation (DNAm) can shed light into the composition of cell types, disease states, and age at death. However, such analysis is hampered by impaired DNA quality and little is known how decomposition affects DNAm. In this study, we determined if EPIC Illumina BeadChip technology is applicable for specimen from mummies of the 18th century CE. Overall, the signal intensity on the microarray was extremely low, but for one of two samples we detected characteristic DNAm signals in a subset of CG dinucleotides (CpGs), which were selected with a stringent processing pipeline. Using only these CpGs we could train epigenetic signatures with reference DNAm profiles of multiple tissues and our predictions were in line with the fact that the specimen was lung tissue of a female 28-year-old donor. Thus, we provide proof of principle that Illumina BeadChips are applicable for DNAm profiling in ancient samples.
Project description:Reconstruction of ancient epigenomes by DNA methylation (DNAm) can shed light into the composition of cell types, disease states, and age at death. However, such analysis is hampered by impaired DNA quality and little is known how decomposition affects DNAm. In this study, we determined if EPIC Illumina BeadChip technology is applicable for specimens from mummies of the eighteenth century CE. Overall, the signal intensity on the microarray was extremely low, but for one of two samples we were able to detect characteristic DNAm signals in a subset of CG dinucleotides (CpGs), which were selected with a stringent processing pipeline. Using only these CpGs we could train epigenetic signatures with reference DNAm profiles of multiple tissues and our predictions matched the fact that the specimen was lung tissue from a 28-year-old woman. Thus, we provide proof of principle that Illumina BeadChips are applicable for DNAm profiling in ancient samples.
Project description:We previously reported that gut microbiota induce de novo DNA methylation of the TLR4 gene in intestinal epithelial cells. Since DNA methyltransferase (DNMT) 3 mediates the transfer of methyl groups to any gene undergoing de novo methylation, the question of how gut microbiota induce the recruitment of DNMT3 to specific genes, including TLR4, remains to be addressed. In this study, we tried to identify an adaptor molecule that recruits DNMT3b to the TLR4 gene by comparing expression of DNMT3-interacting proteins between IEC lines with hypermethylated and hypomethylated TLR4 gene.
Project description:DNA methylation is a heritable chromatin modification essential to mammalian development that functions with histone post-translational modifications to regulate chromatin structure and gene expression programs. The epigenetic inheritance of DNA methylation requires the combined actions of DNMT1 and UHRF1, a histone- and DNA-binding RING E3 ubiquitin ligase that facilitates DNMT1 recruitment to sites of newly replicated DNA through the ubiquitylation of histone H3. UHRF1 binds DNA with modest selectivity towards hemi-methylated CpG dinucleotides (HeDNA); however, the contribution of HeDNA sensing to UHRF1 function remains elusive. Here, we reveal that the interaction of UHRF1 with HeDNA is required for DNA methylation inheritance but is dispensable for chromatin interaction, which is governed by reciprocal positive cooperativity between the UHRF1 histone- and DNA-binding domains. We further show that HeDNA functions as an allosteric regulator of UHRF1 ubiquitin ligase activity, directing ubiquitylation towards multiple lysines on the H3 tail adjacent to the UHRF1 histone-binding site. Collectively, our studies define a highly orchestrated epigenetic control mechanism involving modifications both to histones and DNA that facilitate UHRF1 chromatin targeting, H3 ubiquitylation, and DNA methylation inheritance.
Project description:In the male mouse germline, PIWI-interacting RNAs (piRNAs), bound by the PIWI protein MIWI2 (PIWIL4), guide DNA methylation of young active transposons through SPOCD1. However, the underlying mechanisms of SPOCD1-mediated piRNA-directed transposon methylation and whether this pathway functions to protect the human germline remains unknown. We identified loss-of-function variants in human SPOCD1 that cause defective transposon silencing and male infertility. Through the analysis of one of these pathogenic alleles, we discovered that the uncharacterised protein C19ORF84 interacts with SPOCD1. DNMT3C, the DNA methyltransferase responsible for transposon methylation, associates with SPOCD1 and C19ORF84 in foetal gonocytes. Furthermore, C19ORF84 is essential for piRNA-directed DNA methylation and male mouse fertility. Finally, C19ORF84 mediates the in vivo association of SPOCD1 with the de novo methylation machinery. In summary, we have discovered a conserved role for the human piRNA pathway in transposon silencing and C19ORF84, an uncharacterised protein essential for orchestrating piRNA-directed DNA methylation.