scholarly journals Spatial organization of the mammalian genome surveillance machinery in response to DNA strand breaks

2006 ◽  
Vol 173 (2) ◽  
pp. 195-206 ◽  
Author(s):  
Simon Bekker-Jensen ◽  
Claudia Lukas ◽  
Risa Kitagawa ◽  
Fredrik Melander ◽  
Michael B. Kastan ◽  
...  
Keyword(s):  
Spatial Organization ◽  
Protein A ◽  
Dna Strand Breaks ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Ataxia Telangiectasia Mutated ◽  
Interacting Protein ◽  
Atm Kinase ◽  
Strand Breaks ◽  
Dna Strand

We show that DNA double-strand breaks (DSBs) induce complex subcompartmentalization of genome surveillance regulators. Chromatin marked by γ-H2AX is occupied by ataxia telangiectasia–mutated (ATM) kinase, Mdc1, and 53BP1. In contrast, repair factors (Rad51, Rad52, BRCA2, and FANCD2), ATM and Rad-3–related (ATR) cascade (ATR, ATR interacting protein, and replication protein A), and the DNA clamp (Rad17 and -9) accumulate in subchromatin microcompartments delineated by single-stranded DNA (ssDNA). BRCA1 and the Mre11–Rad50–Nbs1 complex interact with both of these compartments. Importantly, some core DSB regulators do not form cytologically discernible foci. These are further subclassified to proteins that connect DSBs with the rest of the nucleus (Chk1 and -2), that assemble at unprocessed DSBs (DNA-PK/Ku70), and that exist on chromatin as preassembled complexes but become locally modified after DNA damage (Smc1/Smc3). Finally, checkpoint effectors such as p53 and Cdc25A do not accumulate at DSBs at all. We propose that subclassification of DSB regulators according to their residence sites provides a useful framework for understanding their involvement in diverse processes of genome surveillance.

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 ATM’s Role in the Repair of DNA Double-Strand Breaks

Genes ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1370
Author(s):  
Atsushi Shibata ◽  
Penny A. Jeggo
Keyword(s):  
Stress Responses ◽  
Ataxia Telangiectasia ◽  
Cell Cycle Checkpoint ◽  
Double Strand Breaks ◽  
Multiple Roles ◽  
Dna Double Strand Breaks ◽  
Ataxia Telangiectasia Mutated ◽  
Dsb Repair ◽  
Strand Breaks ◽  
Cycle Checkpoint

Ataxia telangiectasia mutated (ATM) is a central kinase that activates an extensive network of responses to cellular stress via a signaling role. ATM is activated by DNA double strand breaks (DSBs) and by oxidative stress, subsequently phosphorylating a plethora of target proteins. In the last several decades, newly developed molecular biological techniques have uncovered multiple roles of ATM in response to DNA damage—e.g., DSB repair, cell cycle checkpoint arrest, apoptosis, and transcription arrest. Combinational dysfunction of these stress responses impairs the accuracy of repair, consequently leading to dramatic sensitivity to ionizing radiation (IR) in ataxia telangiectasia (A-T) cells. In this review, we summarize the roles of ATM that focus on DSB 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 The Karyopherin Kap142p/Msn5p Mediates Nuclear Import and Nuclear Export of Different Cargo Proteins

2001 ◽  
Vol 152 (4) ◽  
pp. 729-740 ◽  
Author(s):  
Kimihisa Yoshida ◽  
Günter Blobel
Keyword(s):  
Nuclear Import ◽  
Nuclear Export ◽  
Protein Import ◽  
Protein A ◽  
Double Strand Breaks ◽  
Wild Type ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Highly Sensitive ◽  
Cargo Proteins

We have identified a novel pathway for protein import into the nucleus. Although the product of Saccharomyces cerevisiae gene MSN5 was previously shown to function as a karyopherin (Kap) for nuclear export of various proteins, we discovered a nuclear import pathway mediated by Msn5p (also referred to as Kap142p). We have purified from yeast cytosol a complex containing Kap142p and the trimeric replication protein A (RPA), which is required for multiple aspects of DNA metabolism, including DNA replication, DNA repair, and recombination. In wild-type cells, RPA was localized primarily to the nucleus but, in a KAP142 deletion strain, RPA was mislocalized to the cytoplasm and the strain was highly sensitive to bleomycin (BLM). BLM causes DNA double-strand breaks and, in S. cerevisiae, the DNA damage is repaired predominantly by RPA-dependent homologous recombination. Therefore, our results indicate that in wild-type cells a critical portion of RPA was imported into the nucleus by Kap142p. Like several other import-related Kap–substrate complexes, the endogenous RPA–Kap142p complex was dissociated by RanGTP, but not by RanGDP. All three RPA genes are essential for viability, whereas KAP142 is not. Perhaps explaining this disparity, we observed an interaction between RPA and Kap95p in a strain lacking Kap142p. This interaction could provide a mechanism for import of RPA into the nucleus and cell viability in the absence of Kap142p. Together with published results (Kaffman, A., N.M. Rank, E.M. O'Neill, L.S. Huang, and E.K. O'Shea. 1998. Nature. 396:482–486; Blondel, M., P.M. Alepuz, L.S. Huang, S. Shaham, G. Ammerer, and M. Peter. 1999. Genes Dev. 13:2284–2300; DeVit, M.J., and M. Johnston. 1999. Curr. Biol. 9:1231–1241; Mahanty, S.K., Y. Wang, F.W. Farley, and E.A. Elion. 1999. Cell. 98:501–512) our data indicate that the karyopherin Kap142p is able to mediate nuclear import of one set of proteins and nuclear export of a different set of proteins.

scholarly journals Hyperthermia Activates a Subset of Ataxia-Telangiectasia Mutated Effectors Independent of DNA Strand Breaks and Heat Shock Protein 70 Status

2007 ◽  
Vol 67 (7) ◽  
pp. 3010-3017 ◽  
Author(s):  
Clayton R. Hunt ◽  
Raj K. Pandita ◽  
Andrei Laszlo ◽  
Ryuji Higashikubo ◽  
Manjula Agarwal ◽  
...  
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Ataxia Telangiectasia ◽  
Heat Shock Protein 70 ◽  
Dna Strand Breaks ◽  
Ataxia Telangiectasia Mutated ◽  
Strand Breaks ◽  
Dna Strand

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.

ATM deficiency disrupts Tcra locus integrity and the maturation of CD4+CD8+ thymocytes

Blood ◽  
2006 ◽  
Vol 109 (5) ◽  
pp. 1887-1896 ◽  
Author(s):  
Irina R. Matei ◽  
Rebecca A. Gladdy ◽  
Lauryl M. J. Nutter ◽  
Angelo Canty ◽  
Cynthia J. Guidos ◽  
...  
Keyword(s):  
T Cell ◽  
Ataxia Telangiectasia ◽  
Cell Receptor ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Ataxia Telangiectasia Mutated ◽  
Apoptotic Pathway ◽  
Strand Breaks ◽  
Striking Contrast

Abstract Mutations in ATM (ataxia-telangiectasia mutated) cause ataxia-telangiectasia (AT), a disease characterized by neurodegeneration, sterility, immunodeficiency, and T-cell leukemia. Defective ATM-mediated DNA damage responses underlie many aspects of the AT syndrome, but the basis for the immune deficiency has not been defined. ATM associates with DNA double-strand breaks (DSBs), and some evidence suggests that ATM may regulate V(D)J recombination. However, it remains unclear how ATM loss compromises lymphocyte development in vivo. Here, we show that T-cell receptor β (TCRβ)–dependent proliferation and production of TCRβlow CD4+CD8+ (DP) thymocytes occurred normally in Atm−/− mice. In striking contrast, the postmitotic maturation of TCRβlow DP precursors into TCRβint DP cells and TCRβhi mature thymocytes was profoundly impaired. Furthermore, Atm−/− thymocytes expressed abnormally low amounts of TCRα mRNA and protein. These defects were not attributable to the induction of a BCL-2–sensitive apoptotic pathway. Rather, they were associated with frequent biallelic loss of distal Va gene segments in DP thymocytes, revealing that ATM maintains Tcra locus integrity as it undergoes V(D)J recombination. Collectively, our data demonstrate that ATM loss increases the frequency of aberrant Tcra deletion events, which compromise DP thymocyte maturation and likely promote the generation of oncogenic TCR translocations.

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