Project description:Rnf20 catalyzes lysine 120 mono-ubiquitination of histone H2B (H2Bub1) that has been previously invloved in normal differentiation of embryonic stem (ES) and adult stem cells. However,the mechanims underlying by which Rnf20 is recruited to its target chromosomal loci to generate H2Bub1 is still elusive. Here, we reveal that Fbxl19, a CxxC domain-containing protein, physically interacts with Rnf20, guides it preferentially to CpG island-containing target promoters, and thereby promotes mono-ubiqutination of H2B. We first show that up-regulation of Fbxl19 induces the level of global H2Bub1, while down-regulation of Fbxl19 reduces the level of H2Bub1 in mouse ES cells. Our genome-wide target mapping unveils the preferential occupancy of Fbxl19 on CpG island-containing promoters, and we further show that the binding of Fbxl19 is essential for the recruitment of Rnf20 to its target genes and subsequent H2Bub1. Altogether, our results demonstrate that Fbxl19 plays critical roles in the H2Bub1 pathway by recruiting Rnf20 to CGI target genes specifically and selectively.
Project description:Rnf20 catalyzes lysine 120 mono-ubiquitination of histone H2B (H2Bub1) that has been previously involved in normal differentiation of embryonic stem (ES) and adult stem cells. However, the mechanisms underlying by which Rnf20 is recruited to its target chromosomal loci to generate H2Bub1 are still elusive. Here, we reveal that Fbxl19, a CxxC domain-containing protein, physically interacts with Rnf20, guides it preferentially to CpG island-containing target promoters, and thereby promotes mono-ubiqutination of H2B. We first show that up-regulation of Fbxl19 induces the level of global H2Bub1, while down-regulation of Fbxl19 reduces the level of H2Bub1 in mouse ES cells. Our genome-wide target mapping unveils the preferential occupancy of Fbxl19 on CpG island-containing promoters, and we further show that the binding of Fbxl19 is essential for the recruitment of Rnf20 to its target genes and subsequent H2Bub1. Altogether, our results demonstrate that Fbxl19 plays critical roles in the H2Bub1 pathway by recruiting Rnf20 to CGI target genes specifically and selectively.
Project description:The Mediator complex orchestrates multiple transcription factors with the Pol II apparatus for precise transcriptional control. However, its interplay with the surrounding chromatin remains poorly understood. Here, we analyze differential histone modifications between WT and MED23-/- (KO) cells and identify H2B mono-ubiquitination at lysine 120 (H2Bub) as a MED23-dependent histone modification. Using tandem affinity purification and mass spectrometry, we find that MED23 associates with the RNF20/40 complex, the enzyme for H2Bub, and show that this association is critical for the recruitment of RNF20/40 to chromatin. In a cell-free system, Mediator directly and substantially increases H2Bub on recombinant chromatin through its cooperation with RNF20/40 and the PAF complex. Integrative genome-wide analyses show that MED23 depletion specifically reduces H2Bub on a subset of MED23-contolled genes. Importantly, MED23-coupled H2Bub levels are oppositely regulated during myogenesis and lung carcinogenesis. In sum, these results establish a mechanistic link between the Mediator complex and a critical chromatin modification in coordinating transcription with cell growth and differentiation. To examine the enrichment of H2B ubiquitination, Pol II, H3K4me3, H3K79me3 in WT and KO MED23 MEF cells, we performed H2Bub ChIP-seq, Pol II ChIP-seq, H3K4me3 ChIP-seq and H3K79me3 ChIP-seq assays. 10 high-throughput sequencing data were deposited and WT, KO input data were controls for peak calling.
Project description:Chromatin remodeling plays very important role in cell reprogramming, but its underlying mechanism remains poorly understood. Here, we show that RNF20 is highly expressed at the early stage of reprogramming along with the accumulation of H2B ubiquitination at the same stage, and Rnf20 knockout results in the failure of reprogramming at the initial stage but not the other two stages. RNA-seq showed that Rnf20 knockout mainly affects the early stage of cell reprogramming by impairing the transcription of MET-related genes and early pluripotency genes. Importantly, Rnf20 knockout results in a more compacted chromosomes structure in reprogrammable cells, suppressing the recruitment of reprogramming transcription factors to their proper locations on the chromosomes, and finally resulting in the failure of pluripotent gene network establishment. Our results not only uncover a previously unknown function of RNF20-mediated H2B ubiquitination in cell reprogramming, but also provide mechanistic insights into the epigenetic regulation of reprogrammable cells.
Project description:Chromatin remodeling plays very important role in cell reprogramming, but its underlying mechanism remains poorly understood. Here, we show that RNF20 is highly expressed at the early stage of reprogramming along with the accumulation of H2B ubiquitination at the same stage, and Rnf20 knockout results in the failure of reprogramming at the initial stage but not the other two stages. RNA-seq showed that Rnf20 knockout mainly affects the early stage of cell reprogramming by impairing the transcription of MET-related genes and early pluripotency genes. Importantly, Rnf20 knockout results in a more compacted chromosomes structure in reprogrammable cells, suppressing the recruitment of reprogramming transcription factors to their proper locations on the chromosomes, and finally resulting in the failure of pluripotent gene network establishment. Our results not only uncover a previously unknown function of RNF20- mediated H2B ubiquitination in cell reprogramming, but also provide mechanistic insights into the epigenetic regulation of reprogrammable cells.
Project description:Regulatory elements called CpG islands (CGIs) are associated with the majority of mammalian gene promoters and have been proposed to play an important role in gene expression. The regulatory capacity of CGIs is thought to rely upon a family of proteins that recognise CGIs through their ZF-CxxC DNA binding domains to recruit chromatin-modifying activities to gene promoters. Through studying FBXL19, a poorly characterized ZF-CxxC domain-containing protein, we have discovered that it specifically interacts with the CDK8-Mediator complex in mouse embryonic stem cells (ESCs). Intriguingly, FBXl19 recruits CDK8-Mediator to a subset of CGI-associated promoters of repressed developmental genes in ESCs. We show that FBXL19-dependent recruitment of CDK8 in ESCs is required for the proper induction of the associated genes during ESC differentiation. This is consistent with early embryonic lethality of in FBXl19 deficient mice. Together, our observations highlight a novel role for FBXL19 in priming developmental gene expression, via recruitment of CDK8 to their CGI promoters, in order to support normal gene induction during differentiation and development.
Project description:Regulatory elements called CpG islands (CGIs) are associated with the majority of mammalian gene promoters and have been proposed to play an important role in gene expression. The regulatory capacity of CGIs is thought to rely upon a family of proteins that recognise CGIs through their ZF-CxxC DNA binding domains to recruit chromatin-modifying activities to gene promoters. Through studying FBXL19, a poorly characterized ZF-CxxC domain-containing protein, we have discovered that it specifically interacts with the CDK8-Mediator complex in mouse embryonic stem cells (ESCs). Intriguingly, FBXl19 recruits CDK8-Mediator to a subset of CGI-associated promoters of repressed developmental genes in ESCs. We show that FBXL19-dependent recruitment of CDK8 in ESCs is required for the proper induction of the associated genes during ESC differentiation. This is consistent with early embryonic lethality of in FBXl19 deficient mice. Together, our observations highlight a novel role for FBXL19 in priming developmental gene expression, via recruitment of CDK8 to their CGI promoters, in order to support normal gene induction during differentiation and development.
Project description:Regulatory elements called CpG islands (CGIs) are associated with the majority of mammalian gene promoters and have been proposed to play an important role in gene expression. The regulatory capacity of CGIs is thought to rely upon a family of proteins that recognise CGIs through their ZF-CxxC DNA binding domains to recruit chromatin-modifying activities to gene promoters. Through studying FBXL19, a poorly characterized ZF-CxxC domain-containing protein, we have discovered that it specifically interacts with the CDK8-Mediator complex in mouse embryonic stem cells (ESCs). Intriguingly, FBXl19 recruits CDK8-Mediator to a subset of CGI-associated promoters of repressed developmental genes in ESCs. We show that FBXL19-dependent recruitment of CDK8 in ESCs is required for the proper induction of the associated genes during ESC differentiation. This is consistent with early embryonic lethality of in FBXl19 deficient mice. Together, our observations highlight a novel role for FBXL19 in priming developmental gene expression, via recruitment of CDK8 to their CGI promoters, in order to support normal gene induction during differentiation and development.