Project description:INO80 is an evolutionary conserved nucleosome remodelling complex that acts in transcription, replication and genome stability. It is required for resistance against genotoxic agents and involved in the repair of DNA double-strand breaks (DSB) by homologous recombination (HR). However, causes underlying the HR defect of INO80-C mutant cells have been controversially discussed. We here unite previous findings using a high-resolution system to study HR in the yeast Saccharomyces cerevisiae. We find that INO80-C has at least two distinct functions during HR, which promote DNA end resection and presynaptic filament formation, respectively. Importantly, specifically the second function is linked to the histone variant H2A.Z. In the absence of H2A.Z, presynaptic filament formation and HR are restored in INO80-C-deficient mutants, suggesting that presynaptic filament formation is the crucial INO80-C function during HR.
Project description:Global warming imposes a major threat to plant growth and crop production. In some plants including Arabidopsis thaliana, elevated temperatures induce a series of morphological and developmental adjustments, termed thermomorphogenesis to facilitate plant cooling under high-temperature conditions. Plant thermal response is suppressed by histone variant H2A.Z. At warm temperatures, H2A.Z is evicted from nucleosomes at thermo-responsive genes, resulting in their activation. However, the mechanisms that regulate H2A.Z eviction and subsequent transcription activation are largely unknown. Here, we show that the ino80 chromatin-remodeling complex (ino80-C) promotes thermomorphogenesis and activates the expression of thermo-responsive and auxin-related genes. ino80-C associates with PHYTOCHROME-INTERACTING FACTOR 4 (PIF4), a potent regulator in thermomorphogenesis, and mediates temperature-induced H2A.Z eviction at PIF4 targets. Moreover, ino80-C directly interacts with COMPASS-like and transcription elongation factors to promote active histone modification Histone H3 lysine 4 trimethylation (H3K4me3) and RNA Polymerase II (RNA Pol II) elongation, leading to the thermal induction of transcription. Notably, transcription elongation factors are required for the eviction of H2A.Z at PIF4 targets, suggesting the cooperation of ino80-C and transcription elongation in H2A.Z removal. Our results demonstrate that the (PIF4)-(ino80-C)-(COMPASS-like)-(transcription elongator) module controls plant thermal response, and establish a link between H2A.Z eviction and active transcription.
Project description:Global warming imposes a major threat to plant growth and crop production. In some plants including Arabidopsis thaliana, elevated temperatures induce a series of morphological and developmental adjustments, termed thermomorphogenesis to facilitate plant cooling under high-temperature conditions. Plant thermal response is suppressed by histone variant H2A.Z. At warm temperatures, H2A.Z is evicted from nucleosomes at thermo-responsive genes, resulting in their activation. However, the mechanisms that regulate H2A.Z eviction and subsequent transcription activation are largely unknown. Here, we show that the ino80 chromatin-remodeling complex (ino80-C) promotes thermomorphogenesis and activates the expression of thermo-responsive and auxin-related genes. ino80-C associates with PHYTOCHROME-INTERACTING FACTOR 4 (PIF4), a potent regulator in thermomorphogenesis, and mediates temperature-induced H2A.Z eviction at PIF4 targets. Moreover, ino80-C directly interacts with COMPASS-like and transcription elongation factors to promote active histone modification Histone H3 lysine 4 trimethylation (H3K4me3) and RNA Polymerase II (RNA Pol II) elongation, leading to the thermal induction of transcription. Notably, transcription elongation factors are required for the eviction of H2A.Z at PIF4 targets, suggesting the cooperation of ino80-C and transcription elongation in H2A.Z removal. Our results demonstrate that the (PIF4)-(ino80-C)-(COMPASS-like)-(transcription elongator) module controls plant thermal response, and establish a link between H2A.Z eviction and active transcription.
Project description:Meiotic homologous recombination is a critical DNA-templated event for sexually-reproducing organisms. It is initiated by a programmed formation of DNA double strand breaks (DSBs), mainly formed at recombination hotspots, and is, like all other DNA-related processes, under great influence of chromatin structure. For example, local chromatin around hotspots directly impacts DSB formation. In addition, DSB is proposed to occur in a higher-order chromatin architecture termed “axis-loop”, in which many loops protrude from proteinaceous axis. Despite many recent insightful studies, still much remains unknown about how meiotic DSBs are generated in chromatin structure. Here, we show that the highly conserved histone H2A variant H2A.Z promotes meiotic DSB formation in fission yeast. Subsequent investigation revealed that H2A.Z is neither enriched around hotspots nor axis sites, and that transcript levels of DSB-promoting factors were maintained in the absence of H2A.Z. Instead, we found that H2A.Z facilitates chromatin binding of various proteins required for DSB formation. Strikingly, artificial tethering of one of such proteins, Rec10, to chromatin partially restored DSB reduction in H2A.Z-lacking cells. Based on these, we conclude that fission yeast H2A.Z promotes initiation of meiotic recombination partly through delivering DSB-related proteins onto chromatin.
Project description:Meiotic homologous recombination is a critical DNA-templated event for sexually-reproducing organisms. It is initiated by a programmed formation of DNA double strand breaks (DSBs), mainly formed at recombination hotspots, and is, like all other DNA-related processes, under great influence of chromatin structure. For example, local chromatin around hotspots directly impacts DSB formation. In addition, DSB is proposed to occur in a higher-order chromatin architecture termed “axis-loop”, in which many loops protrude from proteinaceous axis. Despite many recent insightful studies, still much remains unknown about how meiotic DSBs are generated in chromatin structure. Here, we show that the highly conserved histone H2A variant H2A.Z promotes meiotic DSB formation in fission yeast. Subsequent investigation revealed that H2A.Z is neither enriched around hotspots nor axis sites, and that transcript levels of DSB-promoting factors were maintained in the absence of H2A.Z. Instead, we found that H2A.Z facilitates chromatin binding of various proteins required for DSB formation. Strikingly, artificial tethering of one of such proteins, Rec10, to chromatin partially restored DSB reduction in H2A.Z-lacking cells. Based on these, we conclude that fission yeast H2A.Z promotes initiation of meiotic recombination partly through delivering DSB-related proteins onto chromatin.
Project description:INO80 is involved in many chromatin-dependent functions. However, its role in pluripotency has not been fully defined. We examined the impact of Ino80 deletion in the naïve and primed pluripotent stem cells. We found that Ino80 deletion had minimal effect on self-renewal and gene expression in the naïve state, but led to cellular differentiation and de-repression of developmental genes in the primed state. Mechanistically, INO80 co-occupied gene promoters that were bivalently marked by H3K4me3 and H3K27me3. Further, its occupancy was required for H3K27me3 installation and maintenance, as well as downstream gene repression. Finally, INO80 promoted H2A.Z occupancy at the bivalent domains, which in turn facilitated the polycomb repressive complex 2 (PRC2) recruitment. Together, our results identified the INO80-H2A.Z axis as an essential step for bivalent chromatin and poised gene expression and uncovered an epigenetic mechanism by which chromatin remodeling, histone variant, and histone modification coordinately control cell fate.
Project description:INO80 is involved in many chromatin-dependent functions. However, its role in pluripotency has not been fully defined. We examined the impact of Ino80 deletion in the naïve and primed pluripotent stem cells. We found that Ino80 deletion had minimal effect on self-renewal and gene expression in the naïve state, but led to cellular differentiation and de-repression of developmental genes in the primed state. Mechanistically, INO80 co-occupied gene promoters that were bivalently marked by H3K4me3 and H3K27me3. Further, its occupancy was required for H3K27me3 installation and maintenance, as well as downstream gene repression. Finally, INO80 promoted H2A.Z occupancy at the bivalent domains, which in turn facilitated the polycomb repressive complex 2 (PRC2) recruitment. Together, our results identified the INO80-H2A.Z axis as an essential step for bivalent chromatin and poised gene expression and uncovered an epigenetic mechanism by which chromatin remodeling, histone variant, and histone modification coordinately control cell fate.
Project description:INO80 is involved in many chromatin-dependent functions. However, its role in pluripotency has not been fully defined. We examined the impact of Ino80 deletion in the naïve and primed pluripotent stem cells. We found that Ino80 deletion had minimal effect on self-renewal and gene expression in the naïve state, but led to cellular differentiation and de-repression of developmental genes in the primed state. Mechanistically, INO80 co-occupied gene promoters that were bivalently marked by H3K4me3 and H3K27me3. Further, its occupancy was required for H3K27me3 installation and maintenance, as well as downstream gene repression. Finally, INO80 promoted H2A.Z occupancy at the bivalent domains, which in turn facilitated the polycomb repressive complex 2 (PRC2) recruitment. Together, our results identified the INO80-H2A.Z axis as an essential step for bivalent chromatin and poised gene expression and uncovered an epigenetic mechanism by which chromatin remodeling, histone variant, and histone modification coordinately control cell fate.
Project description:INO80 is involved in many chromatin-dependent functions. However, its role in pluripotency has not been fully defined. We examined the impact of Ino80 deletion in the naïve and primed pluripotent stem cells. We found that Ino80 deletion had minimal effect on self-renewal and gene expression in the naïve state, but led to cellular differentiation and de-repression of developmental genes in the primed state. Mechanistically, INO80 co-occupied gene promoters that were bivalently marked by H3K4me3 and H3K27me3. Further, its occupancy was required for H3K27me3 installation and maintenance, as well as downstream gene repression. Finally, INO80 promoted H2A.Z occupancy at the bivalent domains, which in turn facilitated the polycomb repressive complex 2 (PRC2) recruitment. Together, our results identified the INO80-H2A.Z axis as an essential step for bivalent chromatin and poised gene expression and uncovered an epigenetic mechanism by which chromatin remodeling, histone variant, and histone modification coordinately control cell fate.
Project description:HS-10502 is a Poly(ADP-ribose) polymerase 1 (PARP1)-specific selective inhibitor. The purpose if this study is to assess the safety, tolerability, pharmacokinetics (PK), and efficacy of HS-10502 in subjects with homologous recombination repair (HRR) gene mutant or homologous recombination deficiency (HRD) positive advanced solid tumors.