Project description:ATP-dependent chromatin remodeling complexes have been shown to participate in DNA replication in addition to transcription and DNA repair. However, the mechanisms of their involvement in DNA replication remain unclear. Here, we reveal a specific function of the yeast INO80 chromatin remodeling complex in the DNA damage tolerance pathways. Whereas INO80 is necessary for the resumption of replication at forks stalled by methyl methane sulfonate (MMS), it is not required for replication fork collapse after treatment with hydroxyurea (HU). Mechanistically, INO80 regulates DNA damage tolerance during replication through modulation of PCNA (proliferating cell nuclear antigen) ubiquitination and Rad51-mediated processing of recombination intermediates at impeded replication forks. Our findings establish a mechanistic link between INO80 and DNA damage tolerance pathways, indicating that chromatin remodeling is important for accurate DNA replication. INO80 distribution in WT cells was measured.
Project description:Embryonic stem cell (ESC) self-renewal and pluripotency is controlled by the coordinated action of transcription factors and chromatin regulators. Compared to the pluripotency transcription factors, the function of the chromatin regulators, especially the ATP-dependent chromatin remodelers, remains poorly understood in ESCs. Here, we show that INO80, a SWI/SNF family chromatin remodeling complex, is essential for ESC self-renewal, pluripotency, somatic cell reprogramming, and embryonic development. Ino80, the ATPase of the complex, forms an auto-regulatory loop with the ESC master transcription factors Oct4, Nanog, and Sox2. More importantly, it co-occupies the enhancer regions of most key pluripotency genes with the master transcription factors, and positively regulates their expression by maintaining an open chromatin structure. Our data suggests that INO80 is an integral component of the pluripotency transcription network, and plays a critical role in both the maintenance and establishment of pluripotency Identification of Ino80 localization in mouse embryonic stem cells
Project description:INO80 complex is an ATPase-dependent chormatin remodeling complex, which regulates various DNA metabolic processes such as DNA replication and repair. Additionally, INO80 complex also contributes to the regulation of gene expression in sterss response and development. In order to investigate the function of INO80 complex in rhabdomyosarcoma, we examined the knockdown of subunits of INO80 complex Actr5, Ies6, and Ino80 in human rhabdomyosarcoma RD cells. As a result, it was found that INO80 complex is involved in the sarcomagenicity and the disregulation of myogenic properties of rhabdomyosarcoma cells.
Project description:During transcription, nucleosomes are evicted from regulatory and coding regions yet chromatin structure is stable. Restoration of chromatin structure involves concerted action of chromatin modifying activities. Our analysis demonstrates a genome wide function of the INO80 remodeling complex for stable repositioning of the nucleosome immediately proximal to the transcription initiation site. INO80 dependent remodeling of the promoter proximal nucleosomes has a global repressive role. Recruitment of INO80 to proximal nucleosomes overlaps with the elongating Polymerase II complex assembly. The amount of associated Polymerase II at start sites correlates with INO80 recruitment for inducible and constantly transcribed genes. Furthermore, at highly inducible promoters INO80 is required for repression of bidirectional transcription. Therefore, we suggest a function for INO80 after transcription initiation to achieve Polymerase II dependent reassembly of promoter proximal nucleosomes.
Project description:Purpose: Endothelial cell-specific knockout of the INO80 chromatin-remodeling complex in developing mouse embryos results in defective coronary angiogenesis. Transcriptome analysis on whole hearts was performed to understand how Ino80 regulates the genome to influence angiogenesis. Methods: mRNA was extracted from whole hearts after surgical removal from embryonic day 13.5 mice, either WT or Tie2-Ino80 KO, and prepped for Illumina sequencing using the NEBNext Ultra RNA Library Prep kit. Results: Deletion of Ino80 in the two major coronary progenetiors results in intermediate non-compaction phenotypes and an increase in E2F-mediated gene expression and cellular proliferation. Conclusions: Ino80 normally functions to suppress E2F-mediated proliferation in cardiac endothelial cells in order to promote productive angiogenesis and prevent underdevelopment of the myocardium heart muscle. Loss of this critical chromatin-remodeling function results in human disease phenotypes.
Project description:Background: Chromatin remodeling complexes facilitate the access of enzymes that mediate transcription, replication or repair of DNA by modulating nucleosome position and/or composition. Ino80 is the DNA-dependent Snf2-like ATPase subunit of a complex whose nucleosome remodeling activity requires actin-related proteins, Arp4, Arp5 and Arp8, as well as two RuvB-like DNA helicase subunits. Budding yeast mutants deficient for Ino80 function are not only hypersensitive to reagents that induce DNA double strand breaks, but also to those that impair replication fork progression. Results: To understand why ino80 mutants are sensitive to agents that perturb DNA replication, we used chromatin immunoprecipitation to map the binding sites of the Ino80 chromatin remodeling complex on four budding yeast chromosomes. We found that Ino80 and Arp5 binding sites coincide with origins of DNA replication and tRNA genes. In addition, Ino80 was bound at 67% of the promoters of genes that are sensitive to ino80 mutation. When replication forks were arrested near origins in the presence of hydroxyurea (HU), the presence of the Ino80 complex at stalled forks and at unfired origins increased dramatically. Importantly, the resumption of DNA replication after release from a HU block was impaired in the absence of Ino80 activity. Mutant cells accumulated double-strand breaks as they attempted to restart replication. Consistently, ino80-deficient cells, although proficient for checkpoint activation, delay recovery from the checkpoint response. Conclusions: The Ino80 chromatin remodeling complex is enriched at stalled replication forks where it promotes the resumption of replication upon recovery from fork arrest. Keywords: ChIP-chip • The goal of the experiment Genome-wide localization of Ino80 on chromosome in Saccharomyces cerevisiae • Keywords DNA replication, Saccharomyces cerevisiae, Genome tilling array (chromosome III, IV, V, VI) • Experimental factor Distribution of Ino80 in random culture Distribution of Ino80 in G1 phase Distribution of Ino80 in early S phase • Experimental design ChIP analyses: W303 background cells expressing Myc-tagged Ino80 were used for the ChIP using anti-Myc monoclonal antibody (9E11). ChIP-chip analyses: In all cases, hybridization data for ChIP fraction was compared with WCE (whole cell extract) fraction. Saccharomyces cerevisiae affymetrix genome tiling array (SC3456a520015F for chromosome III, IV, V, VI) was used. • Quality control steps taken Confirmation of several loci by quantitative real time PCR.
Project description:Epigenetic regulators are attractive targets for the development of new cancer therapies. Among them, the ATP-dependent chromatin remodeling complexes control the chromatin architecture and play important roles in gene regulation. They are often found to be mutated and de-regulated in cancers, but how they influence the cancer gene expression program during cancer initiation and progression is not fully understood. Here we show that the INO80 chromatin remodeling complex is required for oncogenic transcription and tumor growth in non-small cell lung cancer (NSCLC). Ino80, the SWI/SNF ATPase in the complex, is highly expressed in NSCLC cells compared to normal lung epithelia cells. Further, its expression, as well as that of another subunit Ino80b, negatively correlates with disease prognosis in lung cancer patients. Functionally, Ino80 silencing inhibits NSCLC cell proliferation and anchorage-independent growth in vitro and tumor formation in mouse xenografts. It occupies enhancer regions near lung cancer-associated genes, and its occupancy correlates with increased genome accessibility and enhanced expression of downstream genes. Together, our study defines a critical role of INO80 in promoting oncogenic transcription and NSCLC tumorigenesis, and reveals a potential treatment strategy for inhibiting the cancer transcription network by targeting the INO80 chromatin remodeling complex. Human lung cancer cell line A549 cells were infected with shNT or shIno80, and total RNA was extracted 4 days after infection. The RNA was submitted to RNA-Seq subsequently. For ChIP-Seq, A549 infected with shNT or shIno80, was used for ChIP-Seq for corresponding factors.