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: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:Histone H2B lysine 120 mono-ubiquitination (H2Bub1) catalyzed by Rnf20 has been implicated in normal differentiation of embryonic stem (ES) and adult stem cells. However, it remains unknown how Rnf20 is recruited to its specific target chromosomal loci for the establishment of H2Bub1. Here, we reveal that Fbxl19, a CxxC domain-containing protein, promotes H2Bub1 at the promoters of CpG island-containing genes by interacting with Rnf20. We show that up-regulation of Fbxl19 increases the level of global H2Bub1 in mouse ES cells, while down-regulation of Fbxl19 reduces the level of H2Bub1. Our genome-wide target mapping unveils the preferential occupancy of Fbxl19 on CpG island-containing promoters, and we further discover that chromosomal binding of Fbxl19 is required for H2Bub1 of its targets. Moreover, we reveal that Fbxl19 is critical for proper differentiation of ES cells in collaboration with Rnf20. Altogether, our results demonstrate that Fbxl19 recruitment to CpG islands is required for Rnf20-mediated H2B mono-ubiquitination.
Project description:CpG islands are gene regulatory elements associated with the majority of mammalian promoters, yet how they regulate gene expression remains poorly understood. Here, we identify FBXL19 as a CpG island-binding protein in mouse embryonic stem (ES) cells and show that it associates with the CDK-Mediator complex. We discover that FBXL19 recruits CDK-Mediator to CpG island-associated promoters of non-transcribed developmental genes to prime these genes for activation during cell lineage commitment. We further show that recognition of CpG islands by FBXL19 is essential for mouse development. Together this reveals a new CpG island-centric mechanism for CDK-Mediator recruitment to developmental gene promoters in ES cells and a requirement for CDK-Mediator in priming these developmental genes for activation during cell lineage commitment.
Project description:Histone H2B ubiquitination plays an important role in regulating chromatin organization during gene transcription. It has been shown that RNF20/40 regulates H2B ubiquitination. Here, using protein affinity purification, we have identified WAC as a functional partner of RNF20/40. Depletion of WAC abolishes H2B ubiquitination. WAC interacts with RNF20/40 through its C-terminal coiled-coil region and promotes RNF20/40 s E3 ligase activity for H2B ubiquitination. The N-terminal WW domain of WAC recognizes RNA polymerase II. During gene transcription, WAC targets RNF20/40 to associate with RNA polymerase II complex for H2B ubiquitination at active transcription sites, which regulates transcription. Moreover, WAC-dependent transcription is important for cell-cycle checkpoint activation in response to genotoxic stress. Taken together, our results demonstrate an important regulator for transcription-coupled histone H2B ubiquitination.
Project description:BackgroundSpermatogenesis depends on the supporting of the Sertoli cells and their communications with germ cells. However, the regulation of crosstalk between the Sertoli cells and germ cells remains unclear.ResultsIn this report, we used conditional knockout technology to generate the Sertoli cells-specific knockout of Rnf20 in mice. The Amh-Rnf20-/- male mice were infertile owing to spermatogenic failure that mimic the Sertoli cell-only syndrome (SCOS) in humans. Knockout of Rnf20 resulted in the H2BK120ub loss in the Sertoli cells and impaired the transcription elongation of the Cldn11, a gene encoding a component of tight junction. Notably, RNF20 deficiency disrupted the cell adhesion, caused disorganization of the seminiferous tubules, and led to the apoptotic cell death of both spermatogonia and spermatocytes in the seminiferous tubules.ConclusionsThis study describes a Rnf20 knockout mouse model that recapitulates the Sertoli cell-only syndrome in humans and demonstrates that RNF20 is required for male fertility through regulation of H2B ubiquitination in the Sertoli cells.
Project description:Histone H2B mono-ubiquitination at lysine 120 (ubH2B) has been found to regulate transcriptional elongation by collaborating with the histone chaperone FACT (Facilitates Chromatin Transcription) and plays essential roles in chromatin-based transcriptional processes. However, the mechanism of how ubH2B directly collaborates with FACT at the nucleosome level still remains elusive. In this study, we demonstrate that ubH2B impairs the mechanical stability of the nucleosome and helps to recruit FACT by enhancing the binding of FACT on the nucleosome. FACT prefers to bind and deposit H2A-ubH2B dimers to form an intact nucleosome. Strikingly, the preferable binding of FACT on ubH2B-nucleosome greatly enhances nucleosome stability and maintains its integrity. The stable altered nucleosome state obtained by ubH2B and FACT provides a key platform for gene transcription, as revealed by genome-wide and time-course ChIP-qPCR analyses. Our findings provide mechanistic insights of how ubH2B directly collaborates with FACT to regulate nucleosome dynamics for gene transcription.
Project description:The histone methyltransferase Dot1 is conserved from yeast to human and methylates lysine 79 of histone H3 (H3K79) on the core of the nucleosome. H3K79 methylation by Dot1 affects gene expression and the response to DNA damage, and is enhanced by monoubiquitination of the C-terminus of histone H2B (H2Bub1). To gain more insight into the functions of Dot1, we generated genetic interaction maps of increased-dosage alleles of DOT1. We identified a functional relationship between increased Dot1 dosage and loss of the DUB module of the SAGA co-activator complex, which deubiquitinates H2Bub1 and thereby negatively regulates H3K79 methylation. Increased Dot1 dosage was found to promote H2Bub1 in a dose-dependent manner and this was exacerbated by the loss of SAGA-DUB activity, which also caused a negative genetic interaction. The stimulatory effect on H2B ubiquitination was mediated by the N-terminus of Dot1, independent of methyltransferase activity. Our findings show that Dot1 and H2Bub1 are subject to bi-directional crosstalk and that Dot1 possesses chromatin regulatory functions that are independent of its methyltransferase activity.