Regulation of chromatin architecture by the PWWP domain-containing DNA damage-responsive factor EXPAND1/MUM1

Department of Anatomy, The University of Hong Kong, L1, Laboratory Block, 21 Sassoon Road, Hong Kong SAR.
Molecular cell (Impact Factor: 14.02). 03/2010; 37(6):854-64. DOI: 10.1016/j.molcel.2009.12.040
Source: PubMed


Dynamic changes of chromatin structure facilitate diverse biological events, including DNA replication, repair, recombination, and gene transcription. Recent evidence revealed that DNA damage elicits alterations to the chromatin to facilitate proper checkpoint activation and DNA repair. Here we report the identification of the PWWP domain-containing protein EXPAND1/MUM1 as an architectural component of the chromatin, which in response to DNA damage serves as an accessory factor to promote cell survival. Depletion of EXPAND1/MUM1 or inactivation of its PWWP domain resulted in chromatin compaction. Upon DNA damage, EXPAND1/MUM1 rapidly concentrates at the vicinity of DNA damage sites via its direct interaction with 53BP1. Ablation of this interaction impaired damage-induced chromatin decondensation, which is accompanied by sustained DNA damage and hypersensitivity to genotoxic stress. Collectively, our study uncovers a chromatin-bound factor that serves an accessory role in coupling damage signaling with chromatin changes in response to DNA damage.

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Available from: Yick-Pang Ching, Dec 19, 2013
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    • "The function of this domain is still not known precisely. Recently, proteins containing PWWP domain such as EXPAND1/MUM1 have been shown to play role as an architectural component of the chromatin, promoting cell survival under stress condition [34]. Our findings of DNA changes due to insertion of Pot3 sequences exclusively in copper exposed samples suggest role of MGG_15537 encoded protein containing tyrosinase copper-binding domain signature and PWWP domains in maintaining genome stability under copper stress conditions. "
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    ABSTRACT: A fundamental problem in fungal pathogenesis is to elucidate the evolutionary forces responsible for genomic rearrangements leading to races with fitter genotypes. Understanding the adaptive evolutionary mechanisms requires identification of genomic components and environmental factors reshaping the genome of fungal pathogens to adapt. Herein, Magnaporthe oryzae, a model fungal plant pathogen is used to demonstrate the impact of environmental cues on transposable elements (TE) based genome dynamics. For heat shock and copper stress exposed samples, eight TEs belonging to class I and II family were employed to obtain DNA profiles. Stress induced mutant bands showed a positive correlation with dose/duration of stress and provided evidences of TEs role in stress adaptiveness. Further, we demonstrate that genome dynamics differ for the type/family of TEs upon stress exposition and previous reports of stress induced MAGGY transposition has underestimated the role of TEs in M. oryzae. Here, we identified Pyret, MAGGY, Pot3, MINE, Mg-SINE, Grasshopper and MGLR3 as contributors of high genomic instability in M. oryzae in respective order. Sequencing of mutated bands led to the identification of LTR-retrotransposon sequences within regulatory regions of psuedogenes. DNA transposon Pot3 was identified in the coding regions of chromatin remodelling protein containing tyrosinase copper-binding and PWWP domains. LTR-retrotransposons Pyret and MAGGY are identified as key components responsible for the high genomic instability and perhaps these TEs are utilized by M. oryzae for its acclimatization to adverse environmental conditions. Our results demonstrate how common field stresses change genome dynamics of pathogen and provide perspective to explore the role of TEs in genome adaptability, signalling network and its impact on the virulence of fungal pathogens.
    PLoS ONE 04/2014; 9(4):e94415. DOI:10.1371/journal.pone.0094415 · 3.23 Impact Factor
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    • "In this last case, LEDGF could be involved in DNA repair occurring just after the integration step, through its interaction with TOX4. Interestingly, other PWWP domain proteins, like Msh6 and MUM1/EXPAND, are involved in DNA repair [12], [107], [108] but the role of TOX4 and LEDGF in these repair pathways is not known. "
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    ABSTRACT: PWWP domains are involved in the chromatin attachment of several proteins. They bind to both DNA and proteins and their interaction with specific histone methylation marks define them as a new class of histone code readers. The lens epithelium derived growth factor (LEDGF/p75) contains an N-terminal PWWP domain necessary for its interaction with chromatin but also a C-terminal domain which interacts with several proteins, such as lentiviral integrases. These two domains confer a chromatin-tethering function to LEDGF/p75 and in the case of lentiviral integrases, this tethering participates in the efficiency and site selectivity of integration. Although proteins interacting with LEDGF/p75 C-terminal domain have been extensively studied, no data exist about partners of its PWWP domain regulating its interaction with chromatin. In this study, we report the identification by yeast-two-hybrid of thirteen potential partners of the LEDGF PWWP domain. Five of these interactions were confirmed in mammalian cells, using both a protein complementation assay and co-immunoprecipitation approaches. Three of these partners interact with full length LEDGF/p75, they are specific for PWWP domains of the HDGF family and they require PWWP amino acids essential for the interaction with chromatin. Among them, the transcription activator TOX4 and the splicing cofactor NOVA1 were selected for a more extensive study. These two proteins or their PWWP interacting regions (PIR) colocalize with LEDGF/p75 in Hela cells and interact in vitro in the presence of DNA. Finally, single round VSV-G pseudotyped HIV-1 but not MLV infection is inhibited in cells overexpressing these two PIRs. The observed inhibition of infection can be attributed to a defect in the integration step. Our data suggest that a regulation of LEDGF interaction with chromatin by cellular partners of its PWWP domain could be involved in several processes linked to LEDGF tethering properties, such as lentiviral integration, DNA repair or transcriptional regulation.
    PLoS ONE 11/2013; 8(11):e81217. DOI:10.1371/journal.pone.0081217 · 3.23 Impact Factor
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    • "Antibodies against γH2AX, 53BP1, BRCA1, EXPAND1/MUM1, CtIP, MDC1, RAP80, RAD18, RNF8 and RNF168 were previously described (17–21). Conjugated ubiquitin was detected by anti-FK2 (Upstate). "
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    ABSTRACT: Ubiquitylation plays key roles in DNA damage signal transduction. The current model envisions that lysine63-linked ubiquitin chains, via the concerted action of E3 ubiquitin ligases RNF8-RNF168, are built at DNA double-strand breaks (DSBs) to effectively assemble DNA damage-repair factors for proper checkpoint control and DNA repair. We found that RNF168 is a short-lived protein that is stabilized by the deubiquitylating enzyme USP34 in response to DNA damage. In the absence of USP34, RNF168 is rapidly degraded, resulting in attenuated DSB-associated ubiquitylation, defective recruitment of BRCA1 and 53BP1 and compromised cell survival after ionizing radiation. We propose that USP34 promotes a feed-forward loop to enforce ubiquitin signaling at DSBs and highlight critical roles of ubiquitin dynamics in genome stability maintenance.
    Nucleic Acids Research 07/2013; 41(18). DOI:10.1093/nar/gkt622 · 9.11 Impact Factor
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