RIP-seq for SCML2 and SCML2 mutants in 293T-REx and K562 cells
ABSTRACT: Polycomb repressive complex-1 (PRC1) is essential for the epigenetic regulation of gene expression. SCML2 is a mammalian homolog of Drosophila SCM, a Polycomb-group protein that associates with PRC1. Here, we show that SCML2A, an SCML2 isoform tightly associated to chromatin, contributes to PRC1 localization and also directly enforces repression of certain Polycomb target genes. SCML2A binds to PRC1 via its SPM domain and interacts with ncRNAs through a novel RNA-binding region (RBR). Targeting of SCML2A to chromatin involves the coordinated action of the MBT domains, RNA binding, and interaction with PRC1 through the SPM domain. Deletion of the RBR reduces the occupancy of SCML2A at target genes and overexpression of a mutant SCML2A lacking the RBR causes defects in PRC1 recruitment. These observations point to a role for ncRNAs in regulating SCML2 function and suggest that SCML2 participates in the epigenetic control of transcription directly and in cooperation with PRC1. This is the RIP-seq part of the study
Project description:Polycomb repressive complex-1 (PRC1) is essential for the epigenetic regulation of gene expression. SCML2 is a mammalian homolog of Drosophila SCM, a Polycomb-group protein that associates with PRC1. Here, we show that SCML2A, an SCML2 isoform tightly associated to chromatin, contributes to PRC1 localization and also directly enforces repression of certain Polycomb target genes. SCML2A binds to PRC1 via its SPM domain and interacts with ncRNAs through a novel RNA-binding region (RBR). Targeting of SCML2A to chromatin involves the coordinated action of the MBT domains, RNA binding, and interaction with PRC1 through the SPM domain. Deletion of the RBR reduces the occupancy of SCML2A at target genes and overexpression of a mutant SCML2A lacking the RBR causes defects in PRC1 recruitment. These observations point to a role for ncRNAs in regulating SCML2 function and suggest that SCML2 participates in the epigenetic control of transcription directly and in cooperation with PRC1. This is the ChIP-seq part of the study
Project description:Naturally occurring variations of Polycomb Repressive Complex 1 (PRC1) comprise a core assembly of Polycomb group proteins and additional factors that include, surprisingly, Autism Susceptibility Candidate 2 (AUTS2). While AUTS2 is often disrupted in patients with neuronal disorders, the underlying mechanism is unclear. We investigated the role of AUTS2 as part of a previously identified PRC1 complex (PRC1-AUTS2), and in the context of neurodevelopment. In contrast to the canonical role of PRC1 in gene repression, PRC1-AUTS2 activates transcription. Biochemical studies demonstrate that the CK2 component of PRC1-AUTS2 thwarts PRC1 repressive activity and AUTS2-mediated recruitment of P300 leads to gene activation. ChIP-seq of AUTS2 shows that it regulates neuronal gene expression through promoter association. Conditional CNS targeting of Auts2 in a mouse model leads to various developmental defects. These findings reveal a natural means of subverting PRC1 activity, linking key epigenetic modulators with neuronal functions and diseases. ChIP-seq experiments of PRC1 components, PolII as well as histone modifications were performed either in mouse whole brain or in human 293T-REx lines expressing FLAG/HA-tagged subunits. RNA-seq was performed to analyze the expression profile of mouse whole brain.
Project description:The chromatin modifying activities inherent to polycomb repressive complexes PRC1 and PRC2 play an essential role in gene regulation, cellular differentiation, and development. However, the mechanisms by which these complexes recognize their target sites and function together to form repressive chromatin domains remain poorly understood. Recruitment of PRC1 to target sites has been proposed to occur through a hierarchical process, dependent on the prior nucleation of PRC2 and placement of H3K27me3. Here, using a de novo targeting assay in mouse embryonic stem cells we unexpectedly discover that PRC1-dependent H2AK119ub1 leads to the recruitment of PRC2 and H3K27me3 to effectively initiate a polycomb domain. Genetic ablation of catalytic subunit of the PRC1 complex (RINGA/B) and ChIP-seq analysis of PRC1 and PRC2 components confirmed genome-wide decreases in PRC2 occupancy and H3K27me3 levels at PRC target sites. This activity is restricted to variant PRC1 complexes and genetic ablation experiments reveal that targeting of the variant PCGF1/PRC1 complex by KDM2B to CpG islands is required for polycomb domain formation and normal development. Together these observations provide a surprising new PRC1-dependent logic for PRC2 occupancy and polycomb domain formation. RING1A-/-;RING1Bfl/fl ES cells were treated with 800µM tamoxifen for 48hours and compared to untreated control cells by ChIP-seq for RING1B, SUZ12, EZH2 and H3K27me3.
Project description:we identify Scml2, a subunit of a germ cell-specific polycomb repressive complex 1 (PRC1), as a critical epigenetic modifier that establishes the germline-specific epigenome through two distinct functions. One of these functions is in the stem cell phase of spermatogonia and the other is on meiotic sex chromosomes. During the stem cell phase of spermatogonia, Scml2 establishes Rnf2- dependent ubiquitination of H2A (Rnf2-ubH2A) as an epigenetic memory that subsequently ensures programmed repression of somatic genes during the late stages of spermatogenesis. Additionally, during meiosis, Scml2 interacts with γH2AX and works downstream of the DNA damage response factor Mdc1 on the sex chromosomes and, contrary to autosomes, suppresses Rnf2-ubH2A for proper epigenetic programming of the sex chromosomes. Taken together, Scml2 positively regulates Rnf2-ubH2A on autosomes and negatively regulates Rnf2-ubH2A on the sex chromosomes to establish the germline-specific epigenome in spermatogenesis. Our study reveals a novel layer of epigenetic regulation in the male germline and adds further insight into the functionality of the polycomb proteins. RNA-seq and ChIP-seq analyses using wild-type and Scml2 KO spermatogenic cells
Project description:SFMBT1 is a poorly characterized mammalian MBT domain-containing protein homologous to Drosophila SFMBT, a Polycomb group protein involved in epigenetic regulation of gene expression. Here, we show that SFMBT1 regulates transcription in somatic cells and during spermatogenesis through the formation of a stable complex with LSD1 and CoREST. When bound to its gene targets, SFMBT1 recruits its associated proteins and causes chromatin compaction and transcriptional repression. SFMBT1, LSD1, and CoREST share a large fraction of target genes including those encoding replication-dependent histones. Simultaneous occupancy of histone genes by SFMBT1, LSD1, and CoREST is regulated during the cell cycle and correlates with the loss of RNA polymerase II at these promoters during G2, M, and G1. The interplay between the repressive SFMBT1–LSD1–CoREST complex and RNA polymerase II contributes to the timely transcriptional regulation of histone genes in human cells. SFMBT1, LSD1, and CoREST also form a stable complex in germ cells and their chromatin binding activity is regulated during spermatogenesis. RNA-seq in HeLaS3 cells ctrl compared to triple knockdown for SFMBT1, CoREST, and LSD1
Project description:This SuperSeries is composed of the following subset Series: GSE33653: Direct Recruitment of Polycomb Repressive Complex 1 (PRC1) to Chromatin by Core Binding Transcription Factors (ChIP-Seq) GSE33659: Direct Recruitment of Polycomb Repressive Complex 1 (PRC1) to Chromatin by Core Binding Transcription Factors (microarray) Refer to individual Series
Project description:The heterogeneous nature of mammalian PRC1 complexes has hindered our understanding of their biological functions. Here, we present a comprehensive proteomic and genomic analysis that uncovered six major groups of PRC1 complexes each containing a distinct PCGF subunit, a RING1A/B ubiquitin ligase, and a unique set of associated polypeptides. These PRC1 complexes differ in their genomic localization and only a small subset co-localize with H3K27me3. Further biochemical dissection revealed that the six PCGF–RING1A/B combinations form multiple complexes through association with RYBP or its homolog YAF2, which prevents the incorporation of other canonical PRC1 subunits such as CBX, PHC and SCM. Although both RYBP/YAF2- and CBX/PHC/SCM-containing complexes compact chromatin, only RYBP stimulates the activity of RING1B toward H2AK119ub1, suggesting a central role in PRC1 function. Knockdown of RYBP in ES cells compromised their ability to form embryoid bodies, likely because of defects in cell proliferation and maintenance of H2AK119ub1 level. ChIP-seq experiments of different PRC1 components were performed either on HA-tagged transgenic stable 293T-REx lines or on endogenous subunits using specific antibodies.
Project description:The histone lysine demethylase protein, KDM2B, associates with the PCGF1/PRC1 complex and binds to non-methylated DNA through its ZF-CxxC domain, providing a possible molecular link between CpG island elements and polycomb nucleation (Farcas et al., 2012, Wu et al., 2013). Here, a novel genetic system was designed in which PCGF1/PRC1 targeting could be disrupted in vivo through the ablation of KDM2B-mediated DNA binding. To ablate PCGF1/PRC1 targeting, an exon that encodes most of the KDM2B ZF-CxxC domain and is shared by both the long and short form of the protein was flanked by loxP sites (Kdm2bfl/fl). Homozygous mouse ES cell lines were derived that also stably express a tamoxifen inducible form of CRE-recombinase. CRE induced deletion of the ZF-CxxC domain by the addition of tamoxifen yields KDM2B long and short form proteins that are incapable of binding to CpG island DNA but still remain associated with the PCGF1/PRC1 variant complex. We then assessed genome-wide occupancy of the PRC1 component RING1B and the PRC2 component SUZ12 to examine the impact of losing KDM2B-dependent targeting of polycomb. KDM2Bfl/fl ES cells were treated with 800µM tamoxifen for 72hours and compared to untreated control cells by ChIP-seq for KDM2B, RING1B and SUZ12, and RNA-seq.
Project description:The Polycomb repressive complexes PRC1 and PRC2 play a key role in chromosome silencing by Xist RNA. Previously we have shown that initation of Polycomb recruitment is mediated by the PCGF3/5-PRC1 complex, which catalyses chromosome-wide H2A ubiquitylation (H2AK119u1), signalling recruitment of other PRC1 complexes, and PRC2. However, the molecular basis for PCGF3/5-PRC1 recruitment by Xist RNA remains unknown. Here we define the Xist RNA Polycomb Interaction Domain (XR-PID), a 600 nt element encompassing the Xist B-repeat element. XR-PID is required for Polycomb recruitment by Xist RNA, Xist-mediated chromosome silencing. We identify the RNA-binding protein hnRNPK as the principal XR-PID binding factor required to recruit PCGF3/5-PRC1. Accordingly, synthetically tethering hnRNPK to Xist RNA lacking the B-repeat is sufficient for Xist-dependent Polycomb recruitment. Our findings resolve the molecular mechanism for Polycomb recruitment by Xist RNA, providing key insights into chromatin modification by non-coding RNA. Overall design: Stable cell lines were derived by transfecting the FLXist, XistDXEv or some truncated Xist into P4D7, a Mus domesticus (129S1) x Mus castaneus F1 hybrid mouse embryonic stem cell (mESC) line. Use of a hybrid genetic background facilitated analysis of Xist-mediated silencing. Xist expression was induced upon the Dox treatment. Due to high amount of SNPs located in intronic region, we isolated the nascent transcripts labelled by 4sU, to quantify the silencing efficiency among different Xist constructs.