Project description:Heterochromatin plays essential roles in repressing retrotransposons, e.g. endogenous retroviruses (ERVs) during mammalian development, but the contribution of retrotransposition to lethality observed in embryonic cells deficient for heterochromatin-mediated ERV repression is poorly understood. Here we report that selective degradation of the TRIM28 heterochromatin adapter protein leads to reduced association of transcriptional condensates with loci encoding super-enhancer -driven pluripotency genes in embryonic stem cells, a collapse of the pluripotency transcriptional circuit, and a pre-lethal restriction of pluripotent lineages in mouse embryos. De-repressed ERVs recruit transcriptional condensates in the absence of TRIM28, and ERV RNA facilitates condensation of RNA Polymerase II in vitro. We propose that retrotransposons contribute to the genomic distribution of nuclear condensates, and that RNA species may facilitate “hijacking” of transcriptional condensates in various developmental and disease contexts.
Project description:Histone 3 Lysine 9 (H3K9) methylation is known to be associated with pericentric heterochromatin and important in genomic stability. In this study, we show that trimethylation at H3K9 (H3K9me3) is enriched in an adult neural stem cell niche- the subventricular zone (SVZ) on the walls of the lateral ventricle in both rodent and non-human primate baboon brain. Previous studies have shown that there is significant correlation between baboon and human regarding genomic similarity and brain structure, suggesting that findings in baboon are relevant to human. To understand the function of H3K9me3 in this adult neurogenic niche, we performed genome-wide analyses using ChIP-Seq (chromatin immunoprecipitation and deep-sequencing) and RNA-Seq for in vivo SVZ cells purified from baboon brain. Through integrated analyses of ChIP-Seq and RNA-Seq, we found that H3K9me3-enriched genes associated with cellular maintenance, post-transcriptional and translational modifications, signaling pathways, and DNA replication are expressed, while genes involved in axon/neuron, hepatic stellate cell, or immune-response activation are not expressed. As neurogenesis progresses in the adult SVZ, cell fate restriction is essential to direct proper lineage commitment. Our findings highlight that H3K9me3 repression in undifferentiated SVZ cells is engaged in the maintenance of cell type integrity, implicating a role for H3K9me3 as an epigenetic mechanism to control cell fate transition within this adult germinal niche. SVZ H3K9me3 ChIP-seq profile of an adult baboon subventricular zone was generated by deep sequencing with Illumina HiSeq2000
Project description:Polycomb Repressive Complexes 1 and 2 (PRC1 and PRC2) are histone-modifying and -binding complexes that mediate the formation of facultative heterochromatin and are required for silencing of developmental genes and maintenance of cell fate. Multiple pathways of RNA decay work together to establish and maintain heterochromatin in fission yeast, including a recently identified role for a conserved RNA degradation complex called the rixosome or RIX1 complex. Whether RNA degradation also plays a role in the stability of mammalian heterochromatin remains unknown. Here we show that the rixosome contributes to silencing of many Polycomb targets in human cells. The rixosome associates with human PRC complexes and is enriched at promoters of Polycomb target genes. Importantly, depletion of either the rixosome or Polycomb results in accumulation of paused and elongating RNA polymerase at Polycomb-target genes. We identify point mutations in the RING1B subunit of PRC1 that disrupt the interaction between PRC1 and the rixosome and result in diminished silencing, suggesting that direct recruitment of the rixosome to chromatin is required for silencing. Finally, we show that the RNA kinase activity of the rixosome and the XRN2 exoribonuclease, which degrades RNAs with 5’ mono-phosphate groups generated by the rixosome, are required for silencing. Our findings suggest that rixosome-mediated degradation of nascent RNA is conserved from fission yeast to human, although in human cells the rixosome degrades RNA in facultative rather than constitutive heterochromatin.
Project description:Polycomb Repressive Complexes 1 and 2 (PRC1 and PRC2) are histone-modifying and -binding complexes that mediate the formation of facultative heterochromatin and are required for silencing of developmental genes and maintenance of cell fate. Multiple pathways of RNA decay work together to establish and maintain heterochromatin in fission yeast, including a recently identified role for a conserved RNA degradation complex called the rixosome or RIX1 complex. Whether RNA degradation also plays a role in the stability of mammalian heterochromatin remains unknown. Here we show that the rixosome contributes to silencing of many Polycomb targets in human cells. The rixosome associates with human PRC complexes and is enriched at promoters of Polycomb target genes. Importantly, depletion of either the rixosome or Polycomb results in accumulation of paused and elongating RNA polymerase at Polycomb-target genes. We identify point mutations in the RING1B subunit of PRC1 that disrupt the interaction between PRC1 and the rixosome and result in diminished silencing, suggesting that direct recruitment of the rixosome to chromatin is required for silencing. Finally, we show that the RNA kinase activity of the rixosome and the XRN2 exoribonuclease, which degrades RNAs with 5’ mono-phosphate groups generated by the rixosome, are required for silencing. Our findings suggest that rixosome-mediated degradation of nascent RNA is conserved from fission yeast to human, although in human cells the rixosome degrades RNA in facultative rather than constitutive heterochromatin.
Project description:Histone 3 Lysine 9 (H3K9) methylation is known to be associated with pericentric heterochromatin and important in genomic stability. In this study, we show that trimethylation at H3K9 (H3K9me3) is enriched in an adult neural stem cell niche- the subventricular zone (SVZ) on the walls of the lateral ventricle in both rodent and non-human primate baboon brain. Previous studies have shown that there is significant correlation between baboon and human regarding genomic similarity and brain structure, suggesting that findings in baboon are relevant to human. To understand the function of H3K9me3 in this adult neurogenic niche, we performed genome-wide analyses using ChIP-Seq (chromatin immunoprecipitation and deep-sequencing) and RNA-Seq for in vivo SVZ cells purified from baboon brain. Through integrated analyses of ChIP-Seq and RNA-Seq, we found that H3K9me3-enriched genes associated with cellular maintenance, post-transcriptional and translational modifications, signaling pathways, and DNA replication are expressed, while genes involved in axon/neuron, hepatic stellate cell, or immune-response activation are not expressed. As neurogenesis progresses in the adult SVZ, cell fate restriction is essential to direct proper lineage commitment. Our findings highlight that H3K9me3 repression in undifferentiated SVZ cells is engaged in the maintenance of cell type integrity, implicating a role for H3K9me3 as an epigenetic mechanism to control cell fate transition within this adult germinal niche.
Project description:MS/MS dataset for proteogenomics study of Toxoplasma gondii. The dataset was searched against the official v9 gene model from ToxoDB, and the alternate panels of proteins predicted from RNA-SEQ evidences.
Project description:MS/MS dataset for proteogenomics study of Neospora Caninum. The dataset was searched against the official v10 gene model from ToxoDB, and the alternate panels of proteins predicted from RNA-SEQ evidences.
Project description:Study purpose: to explore the entire spectrum of proteomic and genomic changes (amongst others) involved in diseases and in healthy/control populations. The Study is designed to discover biomarkers, develop and validate diagnostic assays, instruments and therapeutics as well as other medical research. Specifically, researchers may analyze proteins, RNA, DNA copy number changes, including large and small (1,000-100,000 kb) scale rearrangements, transcription profiles, epigenetic modifications, sequence variation, and sequence in both diseased tissue and case-matched germline DNA from Subjects.