scholarly journals Autophosphorylation at serine 1981 stabilizes ATM at DNA damage sites

2009 ◽  
Vol 187 (7) ◽  
pp. 977-990 ◽  
Author(s):  
Sairei So ◽  
Anthony J. Davis ◽  
David J. Chen
Keyword(s):  
Dna Damage ◽  
Cellular Response ◽  
Kinase Activity ◽  
Critical Role ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Ataxia Telangiectasia Mutated ◽  
Atm Kinase ◽  
Strand Breaks ◽  
Damage Response

Ataxia telangiectasia mutated (ATM) plays a critical role in the cellular response to DNA damage. In response to DNA double-strand breaks (DSBs), ATM is autophosphorylated at serine 1981. Although this autophosphorylation is widely considered a sign of ATM activation, it is still not clear if autophosphorylation is required for ATM functions including localization to DSBs and activation of ATM kinase activity. In this study, we show that localization of ATM to DSBs is differentially regulated with the initial localization requiring the MRE11–RAD50–NBS1 complex and sustained retention requiring autophosphorylation of ATM at serine 1981. Autophosphorylated ATM interacts with MDC1 and the latter is required for the prolonged association of ATM to DSBs. Ablation of ATM autophosphorylation or knock-down of MDC1 protein affects the ability of ATM to phosphorylate downstream substrates and confer radioresistance. Together, these data suggest that autophosphorylation at serine 1981 stabilizes ATM at the sites of DSBs, and this is required for a proper DNA damage response.

scholarly journals The ATM protein: The importance of being active

2012 ◽  
Vol 198 (3) ◽  
pp. 273-275 ◽  
Author(s):  
Yosef Shiloh ◽  
Yael Ziv
Keyword(s):  
Cellular Response ◽  
Cancer Therapeutics ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Ataxia Telangiectasia Mutated ◽  
Strand Breaks ◽  
Cell Biol ◽  
Response Network ◽  
Damage Response ◽  
Atm Protein

The ataxia telangiectasia mutated (ATM) protein kinase regulates the cellular response to deoxyribonucleic acid (DNA) double-strand breaks by phosphorylating numerous players in the extensive DNA damage response network. Two papers in this issue (Daniel et al. 2012. J. Cell Biol. http://dx.doi.org/10.1083/jcb201204035; Yamamoto et al. 2012. J. Cell Biol. http://dx.doi.org/10.1083/jcb201204098) strikingly show that, in mice, the presence of a catalytically inactive version of ATM is embryonically lethal. This is surprising because mice completely lacking ATM have a much more moderate phenotype. The findings impact on basic cancer research and cancer therapeutics.

Heterochromatin and the DNA damage response: the need to relaxThis paper is one of a selection of papers in a Special Issue entitled 31st Annual International Asilomar Chromatin and Chromosomes Conference, and has undergone the Journal’s usual peer review process.

2011 ◽  
Vol 89 (1) ◽  
pp. 45-60 ◽  
Author(s):  
Kendra L. Cann ◽  
Graham Dellaire
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Chromatin Structure ◽  
Peer Review Process ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Atm Kinase ◽  
Strand Breaks ◽  
Damage Response ◽  
Chromosomal Mutations

Higher order chromatin structure has an impact on all nuclear functions, including the DNA damage response. Over the past several years, it has become increasingly clear that heterochromatin and euchromatin represent separate entities with respect to both damage sensitivity and repair. The chromatin compaction present in heterochromatin helps to protect this DNA from damage; however, when lesions do occur, the compaction restricts the ability of DNA damage response proteins to access the site, as evidenced by its ability to block the expansion of H2AX phosphorylation. As such, DNA damage in heterochromatin is refractory to repair, which requires the surrounding chromatin structure to be decondensed. In the case of DNA double-strand breaks, this relaxation is at least partially mediated by the ATM kinase phosphorylating and inhibiting the function of the transcriptional repressor KAP1. This review will focus on the functions of KAP1 and other proteins involved in the maintenance or restriction of heterochromatin, including HP1 and TIP60, in the DNA damage response. As heterochromatin is important for maintaining genomic stability, cells must maintain a delicate balance between allowing repair factors access to these regions and ensuring that these regions retain their organization to prevent increased DNA damage and chromosomal mutations.

scholarly journals No Overt Nucleosome Eviction at Deprotected Telomeres

2008 ◽  
Vol 28 (18) ◽  
pp. 5724-5735 ◽  
Author(s):  
Peng Wu ◽  
Titia de Lange
Keyword(s):  
Cellular Response ◽  
Double Strand Breaks ◽  
Nonhomologous End Joining ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Atm Kinase ◽  
Strand Breaks ◽  
Damage Response ◽  
Atr Kinase ◽  
Atm Signaling

ABSTRACT Dysfunctional telomeres elicit the canonical DNA damage response, which includes the activation of the ATM or ATR kinase signaling pathways and end processing by nonhomologous end joining (NHEJ) or homologous recombination (HR). The cellular response to DNA double-strand breaks has been proposed to involve chromatin remodeling and nucleosome eviction, but whether dysfunctional telomeres undergo chromatin reorganization is not known. Here, we report on the nucleosomal organization of telomeres that have become deprotected through the deletion of the shelterin components TRF2 or POT1. We found no evidence of changes in the nucleosomal organization of the telomeric chromatin or nucleosome eviction near the telomere terminus. An unaltered chromatin structure was observed at telomeres lacking TRF2, which activate the ATM kinase and are a substrate for NHEJ. Similarly, telomeres lacking POT1a and POT1b, which activate the ATR kinase, showed no overt nucleosome eviction. Finally, telomeres lacking TRF2 and Ku70, which are processed by HR, appeared to maintain their original nucleosomal organization. We conclude that ATM signaling, ATR signaling, NHEJ, and HR at deprotected telomeres can take place in the absence of overt nucleosome eviction.

scholarly journals Distinct versus overlapping functions of MDC1 and 53BP1 in DNA damage response and tumorigenesis

2008 ◽  
Vol 181 (5) ◽  
pp. 727-735 ◽  
Author(s):  
Katherine Minter-Dykhouse ◽  
Irene Ward ◽  
Michael S.Y. Huen ◽  
Junjie Chen ◽  
Zhenkun Lou
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Tumor Suppression ◽  
Cellular Response ◽  
Dna Double Strand Breaks ◽  
Ataxia Telangiectasia Mutated ◽  
Strand Breaks ◽  
Upstream Regulator ◽  
Damage Response ◽  
Atm Signaling

The importance of the DNA damage response (DDR) pathway in development, genomic stability, and tumor suppression is well recognized. Although 53BP1 and MDC1 have been recently identified as critical upstream mediators in the cellular response to DNA double-strand breaks, their relative hierarchy in the ataxia telangiectasia mutated (ATM) signaling cascade remains controversial. To investigate the divergent and potentially overlapping functions of MDC1 and 53BP1 in the ATM response pathway, we generated mice deficient for both genes. Unexpectedly, the loss of both MDC1 and 53BP1 neither significantly increases the severity of defects in DDR nor increases tumor incidence compared with the loss of MDC1 alone. We additionally show that MDC1 regulates 53BP1 foci formation and phosphorylation in response to DNA damage. These results suggest that MDC1 functions as an upstream regulator of 53BP1 in the DDR pathway and in tumor suppression.

scholarly journals RepID-deficient cancer cells are sensitized to a drug targeting p97/VCP segregase

2021 ◽  
Author(s):  
Sang-Min Jang ◽  
Christophe E. Redon ◽  
Haiqing Fu ◽  
Fred E. Indig ◽  
Mirit I. Aladjem
Keyword(s):  
Dna Damage ◽  
Cancer Cells ◽  
Cell Sorting ◽  
Clonogenic Survival ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Ubiquitinated Proteins ◽  
Damage Response ◽  
Survival Assay

Abstract Background The p97/valosin-containing protein (VCP) complex is a crucial factor for the segregation of ubiquitinated proteins in the DNA damage response and repair pathway. Objective We investigated whether blocking the p97/VCP function can inhibit the proliferation of RepID-deficient cancer cells using immunofluorescence, clonogenic survival assay, fluorescence-activated cell sorting, and immunoblotting. Result p97/VCP was recruited to chromatin and colocalized with DNA double-strand breaks in RepID-deficient cancer cells that undergo spontaneous DNA damage. Inhibition of p97/VCP induced death of RepID-depleted cancer cells. This study highlights the potential of targeting p97/VCP complex as an anticancer therapeutic approach. Conclusion Our results show that RepID is required to prevent excessive DNA damage at the endogenous levels. Localization of p97/VCP to DSB sites was induced based on spontaneous DNA damage in RepID-depleted cancer cells. Anticancer drugs targeting p97/VCP may be highly potent in RepID-deficient cells. Therefore, we suggest that p97/VCP inhibitors synergize with RepID depletion to kill cancer cells.

scholarly journals Sae2 antagonizes Rad9 accumulation at DNA double-strand breaks to attenuate checkpoint signaling and facilitate end resection

2018 ◽  
Vol 115 (51) ◽  
pp. E11961-E11969 ◽  
Author(s):  
Tai-Yuan Yu ◽  
Michael T. Kimble ◽  
Lorraine S. Symington
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Inhibitory Effects ◽  
Checkpoint Signaling ◽  
Synthetic Lethal ◽  
Strand Breaks ◽  
Damage Response ◽  
End Resection

The Mre11-Rad50-Xrs2NBS1 complex plays important roles in the DNA damage response by activating the Tel1ATM kinase and catalyzing 5′–3′ resection at DNA double-strand breaks (DSBs). To initiate resection, Mre11 endonuclease nicks the 5′ strands at DSB ends in a reaction stimulated by Sae2CtIP. Accordingly, Mre11-nuclease deficient (mre11-nd) and sae2Δ mutants are expected to exhibit similar phenotypes; however, we found several notable differences. First, sae2Δ cells exhibit greater sensitivity to genotoxins than mre11-nd cells. Second, sae2Δ is synthetic lethal with sgs1Δ, whereas the mre11-nd sgs1Δ mutant is viable. Third, Sae2 attenuates the Tel1-Rad53CHK2 checkpoint and antagonizes Rad953BP1 accumulation at DSBs independent of Mre11 nuclease. We show that Sae2 competes with other Tel1 substrates, thus reducing Rad9 binding to chromatin and to Rad53. We suggest that persistent Sae2 binding at DSBs in the mre11-nd mutant counteracts the inhibitory effects of Rad9 and Rad53 on Exo1 and Dna2-Sgs1–mediated resection, accounting for the different phenotypes conferred by mre11-nd and sae2Δ mutations. Collectively, these data show a resection initiation independent role for Sae2 at DSBs by modulating the DNA damage checkpoint.

scholarly journals Recent advances in the nucleolar responses to DNA double-strand breaks

2020 ◽  
Vol 48 (17) ◽  
pp. 9449-9461
Author(s):  
Lea Milling Korsholm ◽  
Zita Gál ◽  
Blanca Nieto ◽  
Oliver Quevedo ◽  
Stavroula Boukoura ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Dna Damage Response ◽  
Ribosomal Dna ◽  
Repetitive Sequences ◽  
Dna Lesions ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Damage Response

Abstract DNA damage poses a serious threat to human health and cells therefore continuously monitor and repair DNA lesions across the genome. Ribosomal DNA is a genomic domain that represents a particular challenge due to repetitive sequences, high transcriptional activity and its localization in the nucleolus, where the accessibility of DNA repair factors is limited. Recent discoveries have significantly extended our understanding of how cells respond to DNA double-strand breaks (DSBs) in the nucleolus, and new kinases and multiple down-stream targets have been identified. Restructuring of the nucleolus can occur as a consequence of DSBs and new data point to an active regulation of this process, challenging previous views. Furthermore, new insights into coordination of cell cycle phases and ribosomal DNA repair argue against existing concepts. In addition, the importance of nucleolar-DNA damage response (n-DDR) mechanisms for maintenance of genome stability and the potential of such factors as anti-cancer targets is becoming apparent. This review will provide a detailed discussion of recent findings and their implications for our understanding of the n-DDR. The n-DDR shares features with the DNA damage response (DDR) elsewhere in the genome but is also emerging as an independent response unique to ribosomal DNA and the nucleolus.

scholarly journals DNA double-strand breaks in the Toxoplasma gondii-infected cells by the action of reactive oxygen species

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Haohan Zhuang ◽  
Chaoqun Yao ◽  
Xianfeng Zhao ◽  
Xueqiu Chen ◽  
Yimin Yang ◽  
...  
Keyword(s):  
Dna Damage ◽  
Toxoplasma Gondii ◽  
Double Strand Breaks ◽  
Host Cells ◽  
Oxygen Species ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Damage Response ◽  
Infected Cells

Abstract Background Toxoplasma gondii is an obligate parasite of all warm-blooded animals around the globe. Once infecting a cell, it manipulates the host’s DNA damage response that is yet to be elucidated. The objectives of the present study were three-fold: (i) to assess DNA damages in T. gondii-infected cells in vitro; (ii) to ascertain causes of DNA damage in T. gondii-infected cells; and (iii) to investigate activation of DNA damage responses during T. gondii infection. Methods HeLa, Vero and HEK293 cells were infected with T. gondii at a multiplicity of infection (MOI) of 10:1. Infected cells were analyzed for a biomarker of DNA double-strand breaks (DSBs) γH2AX at 10 h, 20 h or 30 h post-infection using both western blot and immunofluorescence assay. Reactive oxygen species (ROS) levels were measured using 2′,7′-dichlorodihydrofluorescein diacetate (H2DCFDA), and ROS-induced DNA damage was inhibited by a ROS inhibitor N-acetylcysteine (NAC). Lastly, DNA damage responses were evaluated by detecting the active form of ataxia telangiectasia mutated/checkpoint kinase 2 (ATM/CHK2) by western blot. Results γH2AX levels in the infected HeLa cells were significantly increased over time during T. gondii infection compared to uninfected cells. NAC treatment greatly reduced ROS and concomitantly diminished γH2AX in host cells. The phosphorylated ATM/CHK2 were elevated in T. gondii-infected cells. Conclusions Toxoplasma gondii infection triggered DNA DSBs with ROS as a major player in host cells in vitro. It also activated DNA damage response pathway ATM/CHK2. Toxoplasma gondii manages to keep a balance between survival and apoptosis of its host cells for the benefit of its own survival.

scholarly journals Ubiquitylation, neddylation and the DNA damage response

Open Biology ◽  
2015 ◽  
Vol 5 (4) ◽  
pp. 150018 ◽  
Author(s):  
Jessica S. Brown ◽  
Stephen P. Jackson
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Cellular Response ◽  
Dna Double Strand Breaks ◽  
Post Translational Modification ◽  
Strand Breaks ◽  
Damage Sensing ◽  
Damage Response ◽  
Repair Mechanisms ◽  
And Function

Failure of accurate DNA damage sensing and repair mechanisms manifests as a variety of human diseases, including neurodegenerative disorders, immunodeficiency, infertility and cancer. The accuracy and efficiency of DNA damage detection and repair, collectively termed the DNA damage response (DDR), requires the recruitment and subsequent post-translational modification (PTM) of a complex network of proteins. Ubiquitin and the ubiquitin-like protein (UBL) SUMO have established roles in regulating the cellular response to DNA double-strand breaks (DSBs). A role for other UBLs, such as NEDD8, is also now emerging. This article provides an overview of the DDR, discusses our current understanding of the process and function of PTM by ubiquitin and NEDD8, and reviews the literature surrounding the role of ubiquitylation and neddylation in DNA repair processes, focusing particularly on DNA DSB repair.

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