Project description:Chromatin insulators are functionally conserved DNA-protein complexes that are situated throughout the genome and organize independent transcriptional domains. Previous work implicated RNA as an important cofactor in chromatin insulator activity, although the mechanisms by which RNA affects insulator activity are not yet understood. Here we identify the exosome, the highly conserved major cellular 3’ to 5’ RNA degradation machinery, as a physical interactor of CP190-dependent chromatin insulator complexes in Drosophila. High resolution genome-wide profiling of exosome by ChIP-seq in two different embryonic cell lines reveals extensive and specific overlap with the CP190, BEAF-32, and CTCF insulator proteins. Colocalization occurs mainly at promoters but also well-characterized boundary elements, such as scs, scs’, Mcp, and Fab-8. Surprisingly, exosome associates primarily with promoters but not gene bodies, arguing against simple cotranscriptional recruitment to RNA substrates. We find that exosome is recruited to chromatin in a transcription dependent manner, preferentially to highly transcribed genes. Similar to insulator proteins, exosome is also significantly enriched at divergently transcribed promoters. Directed ChIP of exosome in cell lines depleted of insulator proteins shows that CTCF is specifically required for exosome association at Mcp and Fab-8 but not other sites, suggesting that alternate mechanisms must also contribute to exosome chromatin recruitment. Taken together, our results reveal a novel relationship between exosome and chromatin insulators throughout the genome. ChIP-seq of exosome components. RNA-seq after control and exosome subunit knockdown in Drosophila cell lines.
Project description:Nude mice harboring HCC-PDX were subjected to treatment with either vehicle or SP2509, followed by analysis of tumor samples using CUT&Tag-seq assays.
Project description:We attempted to development prediction methods for hepatocellular carcinoma (HCC) in chronic hepatitis C patients who have been successfully treated by anti-viral therapy. 2565 miRNAs in 139 exosome specimens were analyzed.
Project description:Cryptic unstable transcripts (CUTs) are rapidly degraded by the nuclear exosome, however, the way they are recognized and targeted to the exosome is not fully understood. The recently identified Schizosaccharomyces pombe MTREC complex has been shown to promote degradation of meiotic mRNAs and regulatory ncRNAs. Here, we report that the MTREC complex is also the major nuclear exosome targeting complex for CUTs and unspliced mRNAs. MTREC complex specifically binds to CUTs, meiotic mRNAs and unspliced mRNA transcripts and targets these RNAs for degradation by the nuclear exosome, while the TRAMP complex has only a minor role in this process. The MTREC complex physically interacts with the nuclear exosome and with various RNA-binding and -processing complexes, coupling RNA processing to the RNA degradation machinery. Our study reveals the central role of the evolutionarily conserved MTREC complex in RNA quality control, and in the recognition and elimination of aberrant, cryptic transcripts. Genome-wide expression analysis of MTREC, Nuclear Exosome, TRAMP, Nrd complex members All experiments were performed twice in biological replicates, except that rmn1Δ and mmi1Δ mei4-P572 were perfomed once.
Project description:Cryptic unstable transcripts (CUTs) are rapidly degraded by the nuclear exosome, however, the way they are recognized and targeted to the exosome is not fully understood. The recently identified Schizosaccharomyces pombe MTREC complex has been shown to promote degradation of meiotic mRNAs and regulatory ncRNAs. Here, we report that the MTREC complex is also the major nuclear exosome targeting complex for CUTs and unspliced mRNAs. MTREC complex specifically binds to CUTs, meiotic mRNAs and unspliced mRNA transcripts and targets these RNAs for degradation by the nuclear exosome, while the TRAMP complex has only a minor role in this process. The MTREC complex physically interacts with the nuclear exosome and with various RNA-binding and -processing complexes, coupling RNA processing to the RNA degradation machinery. Our study reveals the central role of the evolutionarily conserved MTREC complex in RNA quality control, and in the recognition and elimination of aberrant, cryptic transcripts. All experiments were performed twice in biological replicates.
Project description:Introduction: microRNAs are promising candidate breast cancer biomarkers due to their cancer-specific expression profiles. However, efforts to develop circulating breast cancer biomarkers are challenged by the heterogeneity of microRNAs in the blood. To overcome this challenge, we aimed to develop a molecular profile of microRNAs specifically secreted from breast cancer cells. Our first step towards this direction relates to capturing and analyzing the contents of exosomes, which are small secretory vesicles that selectively encapsulate microRNAs indicative of their cell of origin. To our knowledge, circulating exosome microRNAs have not been well evaluated as biomarkers for breast cancer diagnosis or monitoring. Methods: Exosomes were collected from the conditioned media of human breast cancer cell lines, mouse plasma of patient-derived orthotopic xenograft models (PDX), and human plasma samples. Exosomes were verified by electron microscopy, nanoparticle tracking analysis, and western blot. Cellular and exosome microRNAs from breast cancer cell lines were profiled by next-generation small RNA sequencing. Plasma exosome microRNA expression was analyzed by qRT-PCR analysis. Results: Small RNA sequencing and qRT-PCR analysis showed that several microRNAs are selectively encapsulated or highly enriched in breast cancer exosomes. Importantly, the selectively enriched exosome microRNA, human miR-1246, was detected at significantly higher levels in exosomes isolated from PDX mouse plasma, indicating that tumor exosome microRNAs are released into the circulation and can serve as plasma biomarkers for breast cancer. This observation was extended to human plasma samples where miR-1246 and miR-21 were detected at significantly higher levels in the plasma exosomes of 16 breast cancer patients as compared to the plasma exosomes of healthy control subjects. Receiver Operating Characteristic (ROC) curve analysis indicated that the combination of plasma exosome miR-1246 and miR-21 levels is a better indicator of breast cancer than their individual levels. Conclusions: Our results demonstrate that certain microRNA species, such as miR-21 and miR-1246, are selectively enriched in human breast cancer exosomes and significantly elevated in the plasma of breast cancer patients. These findings indicate a potential new strategy to selectively analyze plasma breast cancer microRNAs indicative of the presence of breast cancer.
Project description:Cryptic unstable transcripts (CUTs) are rapidly degraded by the nuclear exosome, however, the way they are recognized and targeted to the exosome is not fully understood. The recently identified Schizosaccharomyces pombe MTREC complex has been shown to promote degradation of meiotic mRNAs and regulatory ncRNAs. Here, we report that the MTREC complex is also the major nuclear exosome targeting complex for CUTs and unspliced mRNAs. MTREC complex specifically binds to CUTs, meiotic mRNAs and unspliced mRNA transcripts and targets these RNAs for degradation by the nuclear exosome, while the TRAMP complex has only a minor role in this process. The MTREC complex physically interacts with the nuclear exosome and with various RNA-binding and -processing complexes, coupling RNA processing to the RNA degradation machinery. Our study reveals the central role of the evolutionarily conserved MTREC complex in RNA quality control, and in the recognition and elimination of aberrant, cryptic transcripts. RNA sequencing of WT and mutant S.pombe strains, processed data is normalized to median non-intron containing gene-expression, no replicates
Project description:The ability to sequence genomes has far outstripped approaches for deciphering the information they encode. Here we present a suite of techniques, based on ribosome profiling (the deep-sequencing of ribosome-protected mRNA fragments), to provide genome-wide maps of protein synthesis as well as a pulse-chase strategy for determining rates of translation elongation. We exploit the propensity of harringtonine to cause ribosomes to accumulate at sites of translation initiation together with a machine learning algorithm to define protein products systematically. Analysis of translation in mouse embryonic stem cells reveals thousands of strong pause sites and novel translation products. These include amino-terminal extensions and truncations and upstream open reading frames with regulatory potential, initiated at both AUG and non-AUG codons, whose translation changes after differentiation. We also define a new class of short, polycistronic ribosome-associated coding RNAs (sprcRNAs) that encode small proteins. Our studies reveal an unanticipated complexity to mammalian proteomes. Examination of translation in mouse embryonic stem cells and during differentiation into embryoid bodies