Project description:This study aims to investigate whether the passage of human chromosome 21 through the mouse male germline results in changes in the transcriptional deployment of the exogenous chromosome in the offspring generation. We used the Tc1 mouse model that stably carries almost an entire copy of human chromosome 21 and profiled the genome-wide pattern of non-methylated DNA using BioCAP-sequencing (doi: 10.1093/nar/gkr1207) in the livers of male- and female-germline derived Tc1 mice. This dataset contains only the samples for male-germline derived animals, BioCAP-Seq data for female-germline derived animals have already been deposited in Gene Expression Omnibus with the accession number GSE72208.
Project description:It has widely accepted that 5-methylcytosine is the only form of DNA methylation in mammalian genomes, whereas the other forms, such as N6-methyladenine, primarily exist in prokaryotes and only a few eukaryotes. Herein, we demonstrated the surprising presence of N6-methyladenine in mammalian genomes, especially, mouse embryonic stem cells. This modification is enriched at histone variant H2A.X-deposited genomic regions in wild type embryonic stem cells. Our work also showed that a previously unknown DNA demethylase, Alkbh1, is the major demethylase for N6-methyladenine in embryonic stem cells. Increase of N6-methyladenine levels in Alkbh1 deficient cells leads to silencing of genes that regulate embryonic development. Surprisingly, genes located on the X-chromosome, but not the Y-chromosome or autosomes are preferentially silenced by N6-methyladenine. Strikingly, N6-methyladenine in Alkbh1 deficient cells are specifically deposition at young, full-length subfamilies of LINE1 transposons that are strongly enriched on the X chromosome. Furthermore, N6-methyladenine deposition on LINE1s pattern is inversely correlated with their evolutionary age. The deposition of N6-methyladenine results in epigenetic silencing of such L1s, which are otherwise actively transcribed in wild type embryonic stem cells, and the neighboring enhancers and genes. Furthermore, N6-methyladenine induced-silencing resists gene activation signals during embryonic stem cell differentiation. Thus, N6-methyladenine adopts a new function in epigenetic silencing in evolution, distinct from its role in gene activation in other organisms. In summary, our results demonstrate that N6-methyladenine unexpectedly constitutes a crucial component of the epigenetic regulation repertoire in mammalian genomes. First, we used different histone antibodies to enrich for DNA molecules with histone modification or specific variant in mouse ESCs as previously described Native-ChIP methods. Then, co-purified DNA molecules from WT or KO ESCs were subject to HiSeq2000 sequencing and data analysis for histone modification or variant peaks. Native ChIP coupling with HiSeq sequencing
Project description:SNP arrays was combined with next generation sequencing (NGS) to identify an LOH in 16q together with an unreported CTCF missense variant in its zinc finger domain. CTCF is within 16q LOH. We found that germline heterozygous variant I446K became homozygous in the tumor due to a loss of heterozygosity rearrangement affecting the whole q arm on chromosome 16. Based on CTCF role in regulating the epigenetic architechture of the genome, our findings reveal CTCF variant I446K as a link between MRD21 and Wilms tumor predisposition.
Project description:Microarray analysis was performed on in vitro and in vivo-derived RNA from the well characterized S. pyogenes strain 5448 WT and animal-passage variant
Project description:Histone variants are key components of the epigenetic code and evolved to perform specific functions in transcriptional regulation, DNA repair, chromosome segregation and other fundamental processes. H2B.Z is a rare, apicomplexan-specific variant of histone H2B. Here we show that in Plasmodium falciparum H2B.Z localises to euchromatic intergenic regions throughout intraerythrocytic development and together with H2A.Z forms a double-variant nucleosomes subtype. These nucleosomes are enriched in promoters over 3’ intergenic regions and their occupancy generally correlates with the strength of the promoter, but not with its temporal activity. Remarkably, H2B.Z occupancy levels exhibit a clear correlation with the base-composition of the underlying DNA, raising the intriguing possibility that the extreme AT-content of the intergenic regions within the Plasmodium genome might be instructive for histone variant deposition. In summary, our data shows that the H2A.Z/H2B.Z double-variant nucleosome demarcates putative regulatory regions of the P. falciparum epigenome and likely provides a scaffold for dynamic regulation of gene expression in this deadly human pathogen. Genome-wide localization of H2B.Z has been studied at three stages of intraerythrocytic development by Illumina sequencing of chromatin-immunoprecipitated and input DNA.