ABSTRACT: Identification of the all RNA species coding and non-coding in total RNA Relationship between DNMT1-RNA interactions, DNA methylation and gene expression
Project description:The nuclear receptor HNF4A regulates embryonic and post-natal hepatocyte gene expression. Using hepatocyte-specific inactivation in mice, we show that the TAF4 subunit of TFIID acts as a cofactor for HNF4A in vivo and that HNF4A interacts directly with the TAF4-TAF12 heterodimer in vitro. In vivo, TAF4 is required to maintain HNF4A-directed embryonic gene expression at post-natal stages and for HNF4A-directed activation of post-natal gene expression. TAF4 promotes HNF4A occupancy of functional cis-regulatory elements located adjacent to the transcription start sites of post-natal expressed genes and for pre-initiation complex formation required for their expression. Promoter-proximal HNF4A-TFIID interactions are therefore required for pre-initiation complex formation and stable HNF4A occupancy of regulatory elements as two concomitant mutually dependent processes. RNA profiles in wild-type and Taf4-/- livers by deep sequencing
Project description:The RNA interactomes of HeLa and HEK293 cells jointly comprise 1106 RNA-binding proteins (RBPs), with almost half of these lacking well-defined RNA-binding domains (RBDs), suggesting the existence of numerous unknown RNA-binding architectures. Here, we report on “RBDmap”, a new method built on interactome capture, to comprehensively identify the RBDs of native RBPs in HeLa cells. Making use of in vivo UV-crosslinking of RBPs to polyadenylated RNAs, capture on oligo(dT) magnetic beads, sequential proteolytic digestion and LC-MS/MS combined with a sophisticated scoring algorithm, RBDmap “re-discoveres” many known RNA-binding sites (e.g. RRM, KH) of numerous well characterized RBPs and suggests novel RBDs.
Project description:Microphthalmia-associated transcription factor (MITF) is the master regulator of the melanocyte lineage. By tandem affinity purification and mass spectrometry, we present a comprehensive characterisation of the MITF interactome comprising multiple novel cofactors involved in transcription, DNA replication and repair and chromatin organisation, including a BRG1 chromatin remodelling complex comprising CHD7. BRG1 is essential for melanoma cell proliferation in vitro and for normal melanocyte development in vivo. MITF and SOX10 actively recruit BRG1 to a set of MITF-associated regulatory elements (MAREs) at active enhancers. MITF, SOX10 and YY1 bind between two BRG1-occupied nucleosomes thus defining both a combinatorial signature of transcription factors essential for the melanocyte lineage and a specific chromatin organisation of MAREs. Nevertheless, BRG1 silencing enhances MITF occupancy at MAREs showing that BRG1 acts to promote dynamic MITF interactions with chromatin. 19 samples corresponding to mRNA profiles of 501Mel and Hermes3A after MITF, BRG1 or control shRNA-mediated knockdown were generated by deep sequencing in triplicate (in duplicate for 501_shMITF and corresponding control 501_shSCR2), using HiSeq2500.
Project description:TRIM24 and TRIM33 interact to form a corepressor complex that suppresses murine hepatocellular carcinoma (HCC). TRIM24 and TRIM33 cooperatively repress retinoic acid receptor dependent activity of VL30 retro-transposons in hepatocytes in vivo. In TRIM24 knockout hepatocytes, VL30 long terminal repeats (LTRs) generate enhancer (e)RNAs and act as surrogate promoter and enhancer elements deregulating expression of neighbouring genes. We show that a VL30 LTR-derived eRNA is essential to activate the lipocalin 13 gene in hepatocytes in vivo. A further consequence of VL30 de-repression is the accumulation of retro-transcribed VL30 DNA in the cytoplasm of TRIM24-mutant hepatocytes and activation of the viral defence/interferon response. VL30 activation therefore modulates gene expression via the enhancer activity of the LTRs and by activation of the interferon response. Both of these processes are genetically linked to HCC development suggesting that VL30 repression by TRIM24 plays an important role in tumour suppression. RNA profiles in liver of wild type (WT) and Trim24-/- mice by deep sequencing using Illumina GAIIx.
Project description:24 nucleotide siRNAs are central players in RNA-directed DNA methylation (RdDM), a process that establishes DNA methylation at transposable elements to ensure genome stability. The plant-specific RNA polymerase IV (Pol IV) is required for siRNA biogenesis and is thought to transcribe RdDM loci to produce primary transcripts that serve as precursors to siRNAs. Yet, no such transcripts have ever been reported. Here, through RNA sequencing and double-stranded RNA sequencing in genotypes that compromise the dicing of siRNA precursors, we were able to identify Pol IV-dependent transcripts from tens of thousands of loci. We show that Pol IV-dependent transcripts correspond to both DNA strands, while the Pol II-dependent transcripts produced upon de-repression of the loci are derived from primarily one strand. We show that Pol IV-dependent transcripts have a 5â monophosphate, lack a polyA tail at the 3â end, and contain no introns; these features distinguish them from Pol II-dependent transcripts. Moreover, RDR2 is shown to play similar roles with Pol IV in both the abundance of siRNA precursors and siRNAs as well as the CHH DNA methylation. The decreased CHH methylation at dcl234 can inhibit the transcription of Pol IV at DRM2-target sites. Finally, the regulations of siRNA biogenesis were explored. To detect siRNA precursors transcribed by RNA polymerase IV, the genome wide profiling of RNA were carried out at dcl234 and dcl234 nrpd1. Different types of RNA (including Total RNA, polyA+ RNA, polyA- RNA, double stranded RNA) libraries were built to detect different transcripts. RDR2 is a RNA-dependent RNA polymerase in Pol IV complex, so the RNA-seq libraries with the mutation of RDR2 were also built. In addition, smRNA libraries with mutations blocking siRNA biogenesis were also built
Project description:We report the differential roles of an HDAC inhibitor-TSA during hESC nerual commitment. In the initiation of hESC differentiation, TSA could inhibit the downregulation of pluripotency genes to maintain pluripotency, whereas in the neural commitment stage, TSA could promote neural gene expression to assist hESC nerual determination. Examination of gene expression patterns in hESCs, day 4 or day 8 differentiated cells without or with TSA treatment
Project description:Adult-onset diseases can be associated with in utero events, but mechanisms for this remain unknown. The polycomb histone methyltransferase, Ezh2, stabilizes transcription by depositing repressive marks during development that persist into adulthood, but its function in postnatal organ homeostasis is unknown. We show that Ezh2 stabilizes cardiac gene expression and prevents cardiac pathology by repressing the homeodomain transcription factor Six1, which functions in cardiac progenitors but is stably silenced upon cardiac differentiation. Ezh2 deletion in cardiac progenitors caused postnatal myocardial pathology and destabilized cardiac gene expression with activation of Six1-dependent skeletal muscle genes. Six1 induced cardiomyocyte hypertrophy and skeletal muscle gene expression. Furthermore, genetically reducing Six1 levels rescued the pathology of Ezh2-deficient hearts. Thus, Ezh2-mediated repression of Six1 in differentiating cardiac progenitors is essential for stable postnatal heart gene expression and homeostasis. Our results suggest that epigenetic dysregulation in embryonic progenitor cells predisposes to adult disease and dysregulated stress responses. Four samples were analyzed. RNA was obtained from ventricles from two wild type and two Ezh2-deficient hearts.