Project description:The SS18-SSX fusion drives oncogenic transformation in synovial sarcoma by bridging SS18, a member of mSWI/SNF complex, to polycomb repressive complex 1 (PRC1) target genes. Here we show that the SSX C-terminus, via its SSXRD domain, directs SS18-SSX chromatin binding independently of SS18. SSXRD specific targeting is mediated by interaction with H2AK119ub1 and histone MacroH2A with which the fusion overlaps genome wide. Variant Polycomb Repressive Complex 1.1 (PRC1.1) acts as the main depositor of H2AK119ub1 and consequently is required for SS18-SSX occupancy. Importantly, SSX C-terminus not only depends on H2AK119ub1 for localization but also further promotes it and consequently, high H2AK119ub1 levels are acquired during synovial sarcoma development. These results reveal an SS18-SSX/PRC1 autoregulatory feedback-loop that enforces fusion binding and could play a role in a wide-range of cancers and physiological settings where SSX proteins are overexpressed.
Project description:The SS18-SSX fusion drives oncogenic transformation in synovial sarcoma by bridging SS18, a member of mSWI/SNF complex, to polycomb repressive complex 1 (PRC1) target genes. Here we show that the SSX C-terminus, via its SSXRD domain, directs SS18-SSX chromatin binding independently of SS18. SSXRD specific targeting is mediated by interaction with H2AK119ub1 and histone MacroH2A with which the fusion overlaps genome wide. Variant Polycomb Repressive Complex 1.1 (PRC1.1) acts as the main depositor of H2AK119ub1 and consequently is required for SS18-SSX occupancy. Importantly, SSX C-terminus not only depends on H2AK119ub1 for localization but also further promotes it and consequently, high H2AK119ub1 levels are acquired during synovial sarcoma development. These results reveal an SS18-SSX/PRC1 autoregulatory feedback-loop that enforces fusion binding and could play a role in a wide-range of cancers and physiological settings where SSX proteins are overexpressed.
Project description:The SS18-SSX fusion drives oncogenic transformation in synovial sarcoma by bridging SS18, a member of the mSWI/SNF (BAF) complex, to Polycomb repressive complex 1 (PRC1) target genes. Here we show that the ability of SS18-SSX to occupy H2AK119ub1-rich regions is an intrinsic property of its SSX C terminus, which can be exploited by fusion to transcriptional regulators beyond SS18. Accordingly, SS18-SSX recruitment occurs in a manner that is independent of the core components and catalytic activity of BAF. Alternative SSX fusions are also recruited to H2AK119ub1-rich chromatin and reproduce the expression signatures of SS18-SSX by engaging with transcriptional activators. Variant Polycomb repressive complex 1.1 (PRC1.1) acts as the main depositor of H2AK119ub1 and is therefore required for SS18-SSX occupancy. Importantly, the SSX C terminus not only depends on H2AK119ub1 for localization, but also further increases it by promoting PRC1.1 complex stability. Consequently, high H2AK119ub1 levels are a feature of murine and human synovial sarcomas. These results uncover a critical role for SSX-C in mediating gene deregulation in synovial sarcoma by providing specificity to chromatin and further enabling oncofusion binding by enhancing PRC1.1 stability and H2AK119ub1 deposition.
Project description:The SS18-SSX fusion drives oncogenic transformation in synovial sarcoma by bridging SS18, a member of the mSWI/SNF (BAF) complex, to Polycomb repressive complex 1 (PRC1) target genes. Here we show that the ability of SS18-SSX to occupy H2AK119ub1-rich regions is an intrinsic property of its SSX C terminus, which can be exploited by fusion to transcriptional regulators beyond SS18. Accordingly, SS18-SSX recruitment occurs in a manner that is independent of the core components and catalytic activity of BAF. Alternative SSX fusions are also recruited to H2AK119ub1-rich chromatin and reproduce the expression signatures of SS18-SSX by engaging with transcriptional activators. Variant Polycomb repressive complex 1.1 (PRC1.1) acts as the main depositor of H2AK119ub1 and is therefore required for SS18-SSX occupancy. Importantly, the SSX C terminus not only depends on H2AK119ub1 for localization, but also further increases it by promoting PRC1.1 complex stability. Consequently, high H2AK119ub1 levels are a feature of murine and human synovial sarcomas. These results uncover a critical role for SSX-C in mediating gene deregulation in synovial sarcoma by providing specificity to chromatin and further enabling oncofusion binding by enhancing PRC1.1 stability and H2AK119ub1 deposition.
Project description:While prior work has established that articular cartilage arises from Prg4-expressing perichondrial cells, it is not clear how this process is specifically restricted to the perichondrium of synovial joints. We document that the transcription factor Creb5 is necessary to initiate the expression of signaling molecules that both direct the formation of synovial joints and guide perichondrial tissue to form articular cartilage instead of bone. Creb5 promotes the generation of articular chondrocytes from perichondrial precursors in part by inducing expression of Wif1, which blocks a Wnt5a autoregulatory loop in the perichondrium. Postnatal deletion of Creb5 in the articular cartilage leads to loss of both flat superficial zone articular chondrocytes coupled with a loss of both Prg4 and Wif1 expression; and a non-cell autonomous up-regulation of Ctgf. Our findings indicate that Creb5 promotes both joint formation and the subsequent development of articular chondrocytes by disrupting a Wnt5a positive-feedback loop in the perichondrium.
Project description:Estrogen receptor alpha (ERα) is a nuclear receptor linked to progression of the majority of human breast cancers. Following activation ERα regulates the transcription of target genes via DNA binding. Through a genome wide approach we have identified a subset of microRNAs (miRNAs or miRs) modulated by ERα. Among them, miRNAs encoded from 2 paralogous clusters, miR-17-92 and miR-106a-363, were up-regulated. In addition, increased expression of miR-424, miR-542-3p and miR-450, located within the same genomic region and down-regulation of miR-181 family members were observed during the estrogenic response. We observed that ERα alone is sufficient for sustained transcription of miR-17-92 and we show that levels of this cluster increase earlier than miRNAs encoded by it, implicating post-transcriptional regulation. Since miR-17-92 a pri-miRNA, is immediately cleaved by DROSHA to pre-miR-18a, this regulation occurs during the formation of the mature molecule from the precursor. Moreover, pre-miR-18a was significantly up-regulated in ERα-positive breast cancers compared to ERα-negative breast cancers. We also demonstrate that the miRNAs belonging to these paralogous clusters target and down-regulate ERα, while a subset of cluster-derived miRNAs inhibit protein translation of its major oncogenic transcriptional p160 co-activator by targeting AIB1 revealing a negative autoregulatory feedback loop. This pathway adds to the highly regulated cellular response to estrogen that fine tunes ERα transcriptional activity and cell proliferation. 4 time points (0hr,3hr,6hr,12hr) and 4 treatments (TO,JP,TO+TET,JP13+TET) x 3 biological replicates of each condition = 24 arrays
Project description:in this study, we performed the SILAC-MS to identify H2AK119ub1 specific binding proteins.Samples were analyzed on a Q Exactive equipped with an Easy n-LC 1000 HPLC system (Thermo Scientific)
Project description:Estrogen receptor alpha (ERα) is a nuclear receptor linked to progression of the majority of human breast cancers. Following activation ERα regulates the transcription of target genes via DNA binding. Through a genome wide approach we have identified a subset of microRNAs (miRNAs or miRs) modulated by ERα. Among them, miRNAs encoded from 2 paralogous clusters, miR-17-92 and miR-106a-363, were up-regulated. In addition, increased expression of miR-424, miR-542-3p and miR-450, located within the same genomic region and down-regulation of miR-181 family members were observed during the estrogenic response. We observed that ERα alone is sufficient for sustained transcription of miR-17-92 and we show that levels of this cluster increase earlier than miRNAs encoded by it, implicating post-transcriptional regulation. Since miR-17-92 a pri-miRNA, is immediately cleaved by DROSHA to pre-miR-18a, this regulation occurs during the formation of the mature molecule from the precursor. Moreover, pre-miR-18a was significantly up-regulated in ERα-positive breast cancers compared to ERα-negative breast cancers. We also demonstrate that the miRNAs belonging to these paralogous clusters target and down-regulate ERα, while a subset of cluster-derived miRNAs inhibit protein translation of its major oncogenic transcriptional p160 co-activator by targeting AIB1 revealing a negative autoregulatory feedback loop. This pathway adds to the highly regulated cellular response to estrogen that fine tunes ERα transcriptional activity and cell proliferation.