scholarly journals Brc1 Promotes the Focal Accumulation and SUMO Ligase Activity of Smc5-Smc6 during Replication Stress

2018 ◽  
Vol 39 (2) ◽  
Author(s):  
Martina Oravcová ◽  
Mariana C. Gadaleta ◽  
Minghua Nie ◽  
Michael C. Reubens ◽  
Oliver Limbo ◽  
...  
Keyword(s):  
Dna Damage Response ◽  
Genetic Instability ◽  
Genome Stability ◽  
Replication Stress ◽  
Dna Lesions ◽  
Replication Forks ◽  
Response Factors ◽  
Sumo Ligase ◽  
Damage Response ◽  
Key Factor

ABSTRACT As genetic instability drives disease or loss of cell fitness, cellular safeguards have evolved to protect the genome, especially during sensitive cell cycle phases, such as DNA replication. Fission yeast Brc1 has emerged as a key factor in promoting cell survival when replication forks are stalled or collapsed. Brc1 is a multi-BRCT protein that is structurally related to the budding yeast Rtt107 and human PTIP DNA damage response factors, but functional similarities appear limited. Brc1 is a dosage suppressor of a mutation in the essential Smc5-Smc6 genome stability complex and is thought to act in a bypass pathway. In this study, we reveal an unexpectedly intimate connection between Brc1 and Smc5-Smc6 function. Brc1 is required for the accumulation of the Smc5-Smc6 genome stability complex in foci during replication stress and for activation of the intrinsic SUMO ligase activity of the complex by collapsed replication forks. Moreover, we show that the chromatin association and SUMO ligase activity of Smc5-Smc6 require the Nse5-Nse6 heterodimer, explaining how this nonessential cofactor critically supports the DNA repair roles of Smc5-Smc6. We also found that Brc1 interacts with Nse5-Nse6, as well as gamma-H2A, so it can tether Smc5-Smc6 at replicative DNA lesions to promote survival.

scholarly journals Multi-BRCT Domain Protein Brc1 Links Rhp18/Rad18 and γH2A To Maintain Genome Stability during S Phase

2017 ◽  
Vol 37 (22) ◽  
Author(s):  
Michael C. Reubens ◽  
Sophie Rozenzhak ◽  
Paul Russell
Keyword(s):  
Genome Stability ◽  
Genome Instability ◽  
Replication Stress ◽  
S Phase ◽  
Dna Lesions ◽  
Brct Domain ◽  
Replication Forks ◽  
Content Type ◽  
Domain Protein ◽  
Chromosome Integrity

ABSTRACT DNA replication involves the inherent risk of genome instability, since replisomes invariably encounter DNA lesions or other structures that stall or collapse replication forks during the S phase. In the fission yeast Schizosaccharomyces pombe, the multi-BRCT domain protein Brc1, which is related to budding yeast Rtt107 and mammalian PTIP, plays an important role in maintaining genome integrity and cell viability when cells experience replication stress. The C-terminal pair of BRCT domains in Brc1 were previously shown to bind phosphohistone H2A (γH2A) formed by Rad3/ATR checkpoint kinase at DNA lesions; however, the putative scaffold interactions involving the N-terminal BRCT domains 1 to 4 of Brc1 have remained obscure. Here, we show that these domains bind Rhp18/Rad18, which is an E3 ubiquitin protein ligase that has crucial functions in postreplication repair. A missense allele in BRCT domain 4 of Brc1 disrupts binding to Rhp18 and causes sensitivity to replication stress. Brc1 binding to Rhp18 and γH2A are required for the Brc1 overexpression suppression of smc6-74, a mutation that impairs the Smc5/6 structural maintenance of chromosomes complex required for chromosome integrity and repair of collapsed replication forks. From these findings, we propose that Brc1 provides scaffolding functions linking γH2A, Rhp18, and Smc5/6 complex at damaged replication forks.

scholarly journals Multi-BRCT domain protein Brc1 links Rhp18/Rad18 and γH2A to maintain genome stability during S-phase

2017 ◽  
Author(s):  
Michael C. Reubens ◽  
Sophie Rozenzhak ◽  
Paul Russell
Keyword(s):  
Genome Stability ◽  
Genome Instability ◽  
Replication Stress ◽  
S Phase ◽  
Dna Lesions ◽  
Brct Domain ◽  
Replication Forks ◽  
Histone H2a ◽  
Domain Protein ◽  
Chromosome Integrity

ABSTRACTDNA replication involves the inherent risk of genome instability, as replisomes invariably encounter DNA lesions or other structures that stall or collapse replication forks during S-phase. In the fission yeast Schizosaccharomyces pombe, the multi-BRCT domain protein Brc1, which is related to budding yeast Rtt107 and mammalian PTIP, plays an important role in maintaining genome integrity and cell viability when cells experience replication stress. The C-terminal pair of BRCT domains in Brc1 were previously shown to bind phospho-histone H2A (γH2A) formed by Rad3/ATR checkpoint kinase at DNA lesions; however, the putative scaffold interactions involving the N-terminal BRCT domains 1-4 of Brc1 have remained obscure. Here we show that these domains bind Rhp18/Rad18, which is an E3 ubiquitin protein ligase that has crucial functions in postreplication repair. A missense allele in BRCT domain 4 of Brc1 disrupts binding to Rhp18 and causes sensitivity to replication stress. Brc1 binding to Rhp18 and γH2A are required for the Brc1-overexpression suppression of smc6-74, which impairs the Smc5/6 structural maintenance of chromosomes complex required for chromosome integrity and repair of collapsed replication forks. From these findings we propose that Brc1 provides scaffolding functions linking γH2A, Rhp18, and Smc5/6 complex at damaged replication forks.

scholarly journals AURKB/Ipl1 restarts replication forks to recover from replication stress.

2021 ◽  
Author(s):  
Erin Moran ◽  
Katherine E Pfister ◽  
Kizhakke Mattada Sathyan ◽  
Brianne Vignero ◽  
Daniel J Burke ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Dna Damage Response ◽  
Chromosome Instability ◽  
Replication Stress ◽  
Aurora Kinase ◽  
S Phase ◽  
Replication Forks ◽  
Aurora Kinase B ◽  
Dna Damaging Agents ◽  
Damage Response

Aurora kinase B (AURKB in human, Ipl1 in S. cerevisiae) is a master regulator of mitosis and its dysregulation has been implicated in chromosome instability. AURKB accumulates in the nucleus in S-phase and is regulated by CHK1 but has not been implicated in in the DNA Damage Response (DDR). Here we show that AURKB has a conserved role to recover from replication stress and restart replication forks. Active AURKB is localized to replication forks after a prolonged arrest. CHK1 phosphorylation of AURKB induces activating phosphorylation of PLK1 and both Aurora and Plk1 are required to deactivate the DDR. Clinical trials with AURKB inhibitors are designed to target established roles for AURKB in mitosis. Our data suggest combinations of AURKB inhibitors and DNA damaging agents could be of therapeutic importance.

scholarly journals MOF Suppresses Replication Stress and Contributes to Resolution of Stalled Replication Forks

2018 ◽  
Vol 38 (6) ◽  
Author(s):  
Dharmendra Kumar Singh ◽  
Raj K. Pandita ◽  
Mayank Singh ◽  
Sharmistha Chakraborty ◽  
Shashank Hambarde ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Replication Stress ◽  
Replication Forks ◽  
Loop Formation ◽  
Origin Firing ◽  
Damage Site ◽  
Replicative Stress ◽  
Damage Response ◽  
Stalled Replication Forks

ABSTRACT The human MOF (hMOF) protein belongs to the MYST family of histone acetyltransferases and plays a critical role in transcription and the DNA damage response. MOF is essential for cell proliferation; however, its role during replication and replicative stress is unknown. Here we demonstrate that cells depleted of MOF and under replicative stress induced by cisplatin, hydroxyurea, or camptothecin have reduced survival, a higher frequency of S-phase-specific chromosome damage, and increased R-loop formation. MOF depletion decreased replication fork speed and, when combined with replicative stress, also increased stalled replication forks as well as new origin firing. MOF interacted with PCNA, a key coordinator of replication and repair machinery at replication forks, and affected its ubiquitination and recruitment to the DNA damage site. Depletion of MOF, therefore, compromised the DNA damage repair response as evidenced by decreased Mre11, RPA70, Rad51, and PCNA focus formation, reduced DNA end resection, and decreased CHK1 phosphorylation in cells after exposure to hydroxyurea or cisplatin. These results support the argument that MOF plays an important role in suppressing replication stress induced by genotoxic agents at several stages during the DNA damage response.

scholarly journals DNA Damage Response in Multiple Myeloma: The Role of the Tumor Microenvironment

Cancers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 504
Author(s):  
Takayuki Saitoh ◽  
Tsukasa Oda
Keyword(s):  
Multiple Myeloma ◽  
Dna Damage ◽  
Dna Repair ◽  
Tumor Microenvironment ◽  
Dna Damage Response ◽  
Genetic Instability ◽  
Dna Repair Mechanisms ◽  
Damage Response ◽  
Repair Mechanisms

Multiple myeloma (MM) is an incurable plasma cell malignancy characterized by genomic instability. MM cells present various forms of genetic instability, including chromosomal instability, microsatellite instability, and base-pair alterations, as well as changes in chromosome number. The tumor microenvironment and an abnormal DNA repair function affect genetic instability in this disease. In addition, states of the tumor microenvironment itself, such as inflammation and hypoxia, influence the DNA damage response, which includes DNA repair mechanisms, cell cycle checkpoints, and apoptotic pathways. Unrepaired DNA damage in tumor cells has been shown to exacerbate genomic instability and aberrant features that enable MM progression and drug resistance. This review provides an overview of the DNA repair pathways, with a special focus on their function in MM, and discusses the role of the tumor microenvironment in governing DNA repair mechanisms.

scholarly journals The Intra- and Extra-Telomeric Role of TRF2 in the DNA Damage Response

2021 ◽  
Vol 22 (18) ◽  
pp. 9900
Author(s):  
Siti A. M. Imran ◽  
Muhammad Dain Yazid ◽  
Wei Cui ◽  
Yogeswaran Lokanathan
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Response Factors ◽  
Telomere Repeat ◽  
Protection Mechanism ◽  
Dna Instability ◽  
Binding Factor ◽  
Damage Response ◽  
Dna Break

Telomere repeat binding factor 2 (TRF2) has a well-known function at the telomeres, which acts to protect the telomere end from being recognized as a DNA break or from unwanted recombination. This protection mechanism prevents DNA instability from mutation and subsequent severe diseases caused by the changes in DNA, such as cancer. Since TRF2 actively inhibits the DNA damage response factors from recognizing the telomere end as a DNA break, many more studies have also shown its interactions outside of the telomeres. However, very little has been discovered on the mechanisms involved in these interactions. This review aims to discuss the known function of TRF2 and its interaction with the DNA damage response (DDR) factors at both telomeric and non-telomeric regions. In this review, we will summarize recent progress and findings on the interactions between TRF2 and DDR factors at telomeres and outside of telomeres.

scholarly journals MORC2 regulates DNA damage response through a PARP1-dependent pathway

2019 ◽  
Vol 47 (16) ◽  
pp. 8502-8520 ◽  
Author(s):  
Lin Zhang ◽  
Da-Qiang Li
Keyword(s):  
Dna Damage ◽  
Zinc Finger ◽  
Chromatin Remodeling ◽  
Dna Damage Response ◽  
Mammalian Cells ◽  
Cellular Response ◽  
Genotoxic Stress ◽  
Underlying Mechanism ◽  
Dna Lesions ◽  
Damage Response

Abstract Microrchidia family CW-type zinc finger 2 (MORC2) is a newly identified chromatin remodeling enzyme with an emerging role in DNA damage response (DDR), but the underlying mechanism remains largely unknown. Here, we show that poly(ADP-ribose) polymerase 1 (PARP1), a key chromatin-associated enzyme responsible for the synthesis of poly(ADP-ribose) (PAR) polymers in mammalian cells, interacts with and PARylates MORC2 at two residues within its conserved CW-type zinc finger domain. Following DNA damage, PARP1 recruits MORC2 to DNA damage sites and catalyzes MORC2 PARylation, which stimulates its ATPase and chromatin remodeling activities. Mutation of PARylation residues in MORC2 results in reduced cell survival after DNA damage. MORC2, in turn, stabilizes PARP1 through enhancing acetyltransferase NAT10-mediated acetylation of PARP1 at lysine 949, which blocks its ubiquitination at the same residue and subsequent degradation by E3 ubiquitin ligase CHFR. Consequently, depletion of MORC2 or expression of an acetylation-defective PARP1 mutant impairs DNA damage-induced PAR production and PAR-dependent recruitment of DNA repair proteins to DNA lesions, leading to enhanced sensitivity to genotoxic stress. Collectively, these findings uncover a previously unrecognized mechanistic link between MORC2 and PARP1 in the regulation of cellular response to DNA damage.

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