scholarly journals Differential Roles of ATM- and Chk2-Mediated Phosphorylations of Hdmx in Response to DNA Damage

2006 ◽  
Vol 26 (18) ◽  
pp. 6819-6831 ◽  
Author(s):  
Yaron Pereg ◽  
Suzanne Lam ◽  
Amina Teunisse ◽  
Sharon Biton ◽  
Erik Meulmeester ◽  
...  
Keyword(s):  
Dna Damage ◽  
Protein Kinase ◽  
Posttranslational Modifications ◽  
Genomic Stability ◽  
Double Strand Breaks ◽  
Nuclear Accumulation ◽  
Strand Breaks ◽  
Damage Response ◽  
Subsequent Degradation ◽  
Atm Protein

ABSTRACT The p53 tumor suppressor plays a major role in maintaining genomic stability. Its activation and stabilization in response to double strand breaks (DSBs) in DNA are regulated primarily by the ATM protein kinase. ATM mediates several posttranslational modifications on p53 itself, as well as phosphorylation of p53's essential inhibitors, Hdm2 and Hdmx. Recently we showed that ATM- and Hdm2-dependent ubiquitination and subsequent degradation of Hdmx following DSB induction are mediated by phosphorylation of Hdmx on S403, S367, and S342, with S403 being targeted directly by ATM. Here we show that S367 phosphorylation is mediated by the Chk2 protein kinase, a downstream kinase of ATM. This phosphorylation, which is important for subsequent Hdmx ubiquitination and degradation, creates a binding site for 14-3-3 proteins which controls nuclear accumulation of Hdmx following DSBs. Phosphorylation of S342 also contributed to optimal 14-3-3 interaction and nuclear accumulation of Hdmx, but phosphorylation of S403 did not. Our data indicate that binding of a 14-3-3 dimer and subsequent nuclear accumulation are essential steps toward degradation of p53's inhibitor, Hdmx, in response to DNA damage. These results demonstrate a sophisticated control by ATM of a target protein, Hdmx, which itself is one of several ATM targets in the ATM-p53 axis of the DNA damage response.

scholarly journals Phosphorylation of Histone H2B at DNA Double-Strand Breaks

2004 ◽  
Vol 199 (12) ◽  
pp. 1671-1677 ◽  
Author(s):  
Oscar Fernandez-Capetillo ◽  
C. David Allis ◽  
André Nussenzweig
Keyword(s):  
Dna Damage ◽  
Posttranslational Modifications ◽  
Double Strand Breaks ◽  
Late Time ◽  
Dna Double Strand Breaks ◽  
Histone Tails ◽  
Histone H2b ◽  
Strand Breaks ◽  
Phosphorylated Form ◽  
Damage Response

Posttranslational modifications of histone tails regulate numerous biological processes including transcription, DNA repair, and apoptosis. Although recent studies suggest that structural alterations in chromatin are critical for triggering the DNA damage response, very little is known about the nature of DNA damage-induced chromatin perturbations. Here we show that the serine 14 residue in the NH2-terminal tail of histone H2B is rapidly phosphorylated at sites of DNA double-strand breaks. At late time points after irradiation, the phosphorylated form of H2B, H2B-Ser14P, accumulates into irradiation-induced foci. H2B-Ser14P foci formation is not associated with the apoptotic phosphorylation of H2B but is strictly dependent on the phosphorylated isoform of H2AX. Our results broaden the spectrum of histone modifications that constitute the DNA damage “histone code” and suggest a model for the underlying chromatin structure within damage-induced foci.

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 Live-cell chromosome dynamics in Arabidopsis thaliana reveals increased chromatin mobility in response to DNA damage

2021 ◽  
Author(s):  
Anis Meschichi ◽  
Adrien Sicard ◽  
Frédéric Pontvianne ◽  
Svenja Reeck ◽  
Stefanie Rosa
Keyword(s):  
Dna Damage ◽  
Arabidopsis Thaliana ◽  
Genome Instability ◽  
High Mobility ◽  
Double Strand Breaks ◽  
Nuclear Space ◽  
Strand Breaks ◽  
Homologous Sequences ◽  
Damage Response ◽  
Repair Mechanisms

Double-strand breaks (DSBs) are a particularly deleterious type of DNA damage potentially leading to translocations and genome instability. Homologous recombination (HR) is a conservative repair pathway in which intact homologous sequences are used as a template for repair. How damaged DNA molecules search for homologous sequences in the crowded space of the cell nucleus is, however, still poorly understood, especially in plants. Here, we measured global chromosome and DSB site mobility, in Arabidopsis thaliana, by tracking the motion of specific loci using the lacO/LacI tagging system and two GFP-tagged HR regulators, RAD51 and RAD54. We observed an increase in chromatin mobility upon the induction of DNA damage, specifically at the S/G2 phases of the cell cycle. Importantly, this increase in mobility was lost on sog1-1 mutant, a central transcription factor of the DNA damage response (DDR), indicating that repair mechanisms actively regulate chromatin mobility upon DNA damage. Interestingly, we observed that DSB sites show remarkably high mobility levels at the early HR stage. Subsequently, a drastic decrease of DSB mobility is observed, which seems to be associated to the relocation of DSBs to the nucleus periphery. Altogether, our data suggest that changes in chromatin mobility are triggered in response to DNA damage, and that this may act as a mechanism to enhance the physical search within the nuclear space to locate a homologous template during homology-directed DNA repair.

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 Feedback regulation of methyl methanesulfonate and ultraviolet-sensitive gene clone 81 via ATM/Chk2 pathway contributes to the resistance of MCF-7 breast cancer cells to cisplatin

Tumor Biology ◽  
2017 ◽  
Vol 39 (3) ◽  
pp. 101042831769430 ◽  
Author(s):  
Juan Lv ◽  
Ying Qian ◽  
Xiaoyan Ni ◽  
Xiuping Xu ◽  
Xuejun Dong
Keyword(s):  
Dna Damage ◽  
Cancer Cells ◽  
Feedback Regulation ◽  
Double Strand Breaks ◽  
Gene Clone ◽  
Methyl Methanesulfonate ◽  
Strand Breaks ◽  
Damage Response ◽  
Dna Replication And Repair ◽  
Mcf 7

The methyl methanesulfonate and ultraviolet-sensitive gene clone 81 protein is a structure-specific nuclease that plays important roles in DNA replication and repair. Knockdown of methyl methanesulfonate and ultraviolet-sensitive gene clone 81 has been found to sensitize cancer cells to chemotherapy. However, the underlying molecular mechanism is not well understood. We found that methyl methanesulfonate and ultraviolet-sensitive gene clone 81 was upregulated and the ATM/Chk2 pathway was activated at the same time when MCF-7 cells were treated with cisplatin. By using lentivirus targeting methyl methanesulfonate and ultraviolet-sensitive gene clone 81 gene, we showed that knockdown of methyl methanesulfonate and ultraviolet-sensitive gene clone 81 enhanced cell apoptosis and inhibited cell proliferation in MCF-7 cells under cisplatin treatment. Abrogation of ATM/Chk2 pathway inhibited cell viability in MCF-7 cells in response to cisplatin. Importantly, we revealed that ATM/Chk2 was required for the upregulation of methyl methanesulfonate and ultraviolet-sensitive gene clone 81, and knockdown of methyl methanesulfonate and ultraviolet-sensitive gene clone 81 resulted in inactivation of ATM/Chk2 pathway in response to cisplatin. Meanwhile, knockdown of methyl methanesulfonate and ultraviolet-sensitive gene clone 81 activated the p53/Bcl-2 pathway in response to cisplatin. These data suggest that the ATM/Chk2 may promote the repair of DNA damage caused by cisplatin by sustaining methyl methanesulfonate and ultraviolet-sensitive gene clone 81, and the double-strand breaks generated by methyl methanesulfonate and ultraviolet-sensitive gene clone 81 may activate the ATM/Chk2 pathway in turn, which provide a novel mechanism of how methyl methanesulfonate and ultraviolet-sensitive gene clone 81 modulates DNA damage response and repair.

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.

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 Damage-induced lncRNAs control the DNA damage response through interaction with DDRNAs at individual double-strand breaks

2017 ◽  
Vol 19 (12) ◽  
pp. 1400-1411 ◽  
Author(s):  
Flavia Michelini ◽  
Sethuramasundaram Pitchiaya ◽  
Valerio Vitelli ◽  
Sheetal Sharma ◽  
Ubaldo Gioia ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Double Strand Breaks ◽  
Strand Breaks ◽  
Damage Response

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.

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