Genome-wide Reinforcement of Cohesin Binding at Pre-existing Cohesin Sites in Response to Ionizing Radiation in Human Cells

Kim, Beom-Jun; Li, Yehua; Zhang, Jinglan; Xi, Yuanxin; Li, Yumei; Yang, Tao; Jung, Sung Yun; Pan, Xuewen; Chen, Rui; Li, Wei; Wang, Yi; Qin, Jun

doi:10.1074/jbc.m110.134577

Cited by 62 publications

(65 citation statements)

References 45 publications

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“…Cohesin-SA1 participates in the intra-S checkpoint without significantly clustering at damage sites, raising the possibility that it functions in this checkpoint pathway at its preexisting binding sites in the genome. In fact, reinforcement of cohesin binding at preexisting binding sites, rather than redistribution to a new location, was observed by ChIP-seq analysis in response to irradiation (58). Importantly, this enhancement of cohesin binding requires SMC phosphorylation by ATM, which is critical for the intra-S checkpoint (58).…”

Section: Discussionmentioning

confidence: 98%

“…In fact, reinforcement of cohesin binding at preexisting binding sites, rather than redistribution to a new location, was observed by ChIP-seq analysis in response to irradiation (58). Importantly, this enhancement of cohesin binding requires SMC phosphorylation by ATM, which is critical for the intra-S checkpoint (58). Interestingly, the increase of cohesin binding at AsiSI-cut sites detected by ChIP analysis (48) coincides with the preexisting cohesin binding sites, suggesting that the observed enhancement of cohesin binding may reflect the reinforcement of cohesin binding related to checkpoint signaling.…”

Section: Discussionmentioning

confidence: 99%

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Distinct Functions of Human Cohesin-SA1 and Cohesin-SA2 in Double-Strand Break Repair

Kong

Ball

Pham

et al. 2014

Molecular and Cellular Biology

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Cohesin is an essential multiprotein complex that mediates sister chromatid cohesion critical for proper segregation of chromosomes during cell division. Cohesin is also involved in DNA double-strand break (DSB) repair. In mammalian cells, cohesin is involved in both DSB repair and the damage checkpoint response, although the relationship between these two functions is unclear. Two cohesins differing by one subunit (SA1 or SA2) are present in somatic cells, but their functional specificities with regard to DNA repair remain enigmatic. We found that cohesin-SA2 is the main complex corecruited with the cohesin-loading factor NIPBL to DNA damage sites in an S/G 2 -phase-specific manner. Replacing the diverged C-terminal region of SA1 with the corresponding region of SA2 confers this activity on SA1. Depletion of SA2 but not SA1 decreased sister chromatid homologous recombination repair and affected repair pathway choice, indicating that DNA repair activity is specifically associated with cohesin recruited to damage sites. In contrast, both cohesin complexes function in the intra-S checkpoint, indicating that cell cyclespecific damage site accumulation is not a prerequisite for cohesin's intra-S checkpoint function. Our findings reveal the unique ways in which cohesin-SA1 and cohesin-SA2 participate in the DNA damage response, coordinately protecting genome integrity in human cells. DNA double-strand breaks (DSBs) are deleterious to genome integrity and can result in chromosomal breakage or translocations and cell death. The two major mechanisms to repair DSBs are the error-prone nonhomologous end joining (NHEJ) and the error-free homologous-recombination (HR) pathways, which involve distinct sets of repair proteins (1). While NHEJ operates throughout the cell cycle, HR utilizes an intact sister chromatid as a repair template and thus is restricted to S/G 2 phase in mammalian cells. Although the two pathways complement one another, the error-free HR pathway is particularly important for accurate damage repair. DSBs also evoke DNA damage checkpoint responses that are mediated by ATM (and the related ATR) (1-3). The G 1 /S and G 2 /M checkpoints, which inhibit cell cycle progression, and the intra-S checkpoint, which inhibits DNA replication, together provide adequate time for DNA repair. Both the checkpoint and the repair functions coordinately maintain genome integrity and stability.The primary function of cohesin is to mediate genome-wide sister chromatid cohesion in a cell cycle-regulated manner to ensure proper segregation of chromosomes in mitosis (4-8). Cohesin contains two SMC proteins (SMC1 and SMC3) and the two non-SMC subunits Rad21 (Scc1) and SA (Scc3 or STAG). Whereas a single Scc3 is present in yeast, two SA proteins, SA1 and SA2, are found in higher eukaryotes that form two distinct cohesin complexes in somatic cells: cohesin-SA1 and cohesin-SA2 (9, 10). Both cohesin-SA1 and cohesin-SA2 contribute to genome-wide sister chromatid cohesion, although SA1 is particularly important for telomeric sister chrom...

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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Distinct Functions of Human Cohesin-SA1 and Cohesin-SA2 in Double-Strand Break Repair

Kong

Ball

Pham

et al. 2014

Molecular and Cellular Biology

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“…Although the acetylation sites of yeast Scc1 are not conserved in human Scc1, and previous mass spectrometry analysis failed to uncover acetylation sites in human Scc1 (Kim et al 2010), it remained formally possible that in addition to abolishing Mms21-dependent sumoylation, Scc1 15KR also eliminated yet unidentified acetylation sites on Scc1. We immunoprecipitated Myc-Scc1 wild type and 15KR from lysates of HeLa Tet-On cells with or without IR treatment and blotted the immunoprecipitations with the antibody against several pan-specific acetyl-lysine antibodies.…”

Section: Expression Of the Smc3 Acetylation-mimicking Mutant Fails Tomentioning

confidence: 99%

Scc1 sumoylation by Mms21 promotes sister chromatid recombination through counteracting Wapl

Kong

et al. 2012

Genes Dev.

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DNA double-strand breaks (DSBs) fuel cancer-driving chromosome translocations. Two related structural maintenance of chromosomes (Smc) complexes, cohesin and Smc5/6, promote DSB repair through sister chromatid homologous recombination (SCR). Here we show that the Smc5/6 subunit Mms21 sumoylates multiple lysines of the cohesin subunit Scc1. Mms21 promotes cohesin-dependent small ubiquitin-like modifier (SUMO) accumulation at laser-induced DNA damage sites in S/G2 human cells. Cells expressing the nonsumoylatable Scc1 mutant (15KR) maintain sister chromatid cohesion during mitosis but are defective in SCR and sensitive to ionizing radiation (IR). Scc1 15KR is recruited to DNA damage sites. Depletion of Wapl, a negative cohesin regulator, rescues SCR defects of Mms21-deficient or Scc1 15KR-expressing cells. Expression of the acetylationmimicking Smc3 mutant does not bypass the requirement for Mms21 in SCR. We propose that Scc1 sumoylation by Mms21 promotes SCR by antagonizing Wapl at a step after cohesin loading at DSBs and in a way not solely dependent on Smc3 acetylation.

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“…Cohesin components Smc1 and Smc3 are phosphorylated by ATM and ATR kinases in response to DNA damage (19,23). Following a single DSB, cohesin is rapidly recruited to all chromosomes in yeast (38,44), whereas cohesin occupancy at preexisting sites is reinforced in human cells upon exposure to ionizing radiation (18). Cohesin is also implicated in transcriptional regulation (see reference 9 for a review).…”

mentioning

confidence: 99%

Calpain-1 Cleaves Rad21 To Promote Sister Chromatid Separation

Panigrahi

Zhang

Mao

et al. 2011

Molecular and Cellular Biology

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Defining the mechanisms of chromosomal cohesion and dissolution of the cohesin complex from chromatids is important for understanding the chromosomal missegregation seen in many tumor cells. Here we report the identification of a novel cohesin-resolving protease and describe its role in chromosomal segregation. Sister chromatids are held together by cohesin, a multiprotein ring-like complex comprised of Rad21, Smc1, Smc3, and SA2 (or SA1). Cohesin is known to be removed from vertebrate chromosomes by two distinct mechanisms, namely, the prophase and anaphase pathways. First, PLK1-mediated phosphorylation of SA2 in prophase leads to release of cohesin from chromosome arms, leaving behind centromeric cohesins that continue to hold the sisters together. Then, at the onset of anaphase, activated separase cleaves the centromeric cohesin Rad21, thereby opening the cohesin ring and allowing the sister chromatids to separate. We report here that the calcium-dependent cysteine endopeptidase calpain-1 is a Rad21 peptidase and normally localizes to the interphase nuclei and chromatin. Calpain-1 cleaves Rad21 at L192, in a calcium-dependent manner. We further show that Rad21 cleavage by calpain-1 promotes separation of chromosome arms, which coincides with a calcium-induced partial loss of cohesin at several chromosomal loci. Engineered cleavage of Rad21 at the calpain-cleavable site without activation of calpain-1 can lead to a loss of sister chromatid cohesion. Collectively, our work reveals a novel function of calpain-1 and describes an additional pathway for sister chromatid separation in humans.DNA replication in S phase generates two identical molecules of chromosomal DNA, known as sister chromatids, which must equally segregate to the two daughter cells in the subsequent mitosis. Therefore, it is important that the sister chromatids are held together from the S phase until proper kinetochore assembly is complete. Such cohesion of the sisters is mediated by a multiprotein ring-like complex called cohesin, which is conserved from Saccharomyces cerevisiae to humans. Cohesin is comprised of four core proteins, namely, Rad21 (Scc1/Mcd1), Smc1, Smc3, and either SA2/Stag2 or SA1/Stag1 (13,22,25,39; reviewed in reference 28). Cohesin undergoes a series of physical and chemical changes during the course of the cell cycle in order to orchestrate the dynamic cohesion and separation between the sister chromatids that are essential for high-fidelity transmission of the genetic material (32). The cohesin cycle includes loading cohesins onto the chromatin of the unpaired chromosome, forming cohesion between the sister chromatids in S phase, regulated freeing of chromosome arms in early mitosis, separation of sister chromatids to allow segregation to opposite poles, and recycling of cohesin molecules for subsequent usage.Cohesin is loaded onto the chromatin in G 1 phase in yeast (25) and in late telophase in vertebrates (21, 39). Loading of cohesin onto chromatin depends on two proteins, Scc2 and Scc4 (8,46). Once it is loaded onto...

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Genome-wide Reinforcement of Cohesin Binding at Pre-existing Cohesin Sites in Response to Ionizing Radiation in Human Cells

Cited by 62 publications

References 45 publications

Distinct Functions of Human Cohesin-SA1 and Cohesin-SA2 in Double-Strand Break Repair

Distinct Functions of Human Cohesin-SA1 and Cohesin-SA2 in Double-Strand Break Repair

Scc1 sumoylation by Mms21 promotes sister chromatid recombination through counteracting Wapl

Calpain-1 Cleaves Rad21 To Promote Sister Chromatid Separation

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