Hypersensitivity of ataxia telangiectasia fibroblasts to ionizing radiation is associated with a repair deficiency of DNA double-strand breaks

The histone variant H2AX is rapidly phosphorylated at the sites of DNA double-strand breaks (DSBs). This phosphorylated H2AX (γ-H2AX) is involved in the retention of repair and signaling factor complexes at sites of DNA damage. The dependency of this phosphorylation on the various PI3K-related protein kinases (in mammals, ataxia telangiectasia mutated and Rad3-related [ATR], ataxia telangiectasia mutated [ATM], and DNA-PKCs) has been a subject of debate; it has been suggested that ATM is required for the induction of foci at DSBs, whereas ATR is involved in the recognition of stalled replication forks. In this study, using Arabidopsis as a model system, we investigated the ATR and ATM dependency of the formation of γ-H2AX foci in M-phase cells exposed to ionizing radiation (IR). We find that although the majority of these foci are ATM-dependent, ∼10% of IR-induced γ-H2AX foci require, instead, functional ATR. This indicates that even in the absence of DNA replication, a distinct subset of IR-induced damage is recognized by ATR. In addition, we find that in plants, γ-H2AX foci are induced at only one-third the rate observed in yeasts and mammals. This result may partly account for the relatively high radioresistance of plants versus yeast and mammals.

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Effects of melatonin on repair of DNA double strand breaks caused by ionizing radiation in rat peripheral blood

Bioscience Biotechnology Research Communications ◽

10.21786/bbrc/9.4/36 ◽

2016 ◽

Vol 9 (4) ◽

pp. 821-827 ◽

Cited By ~ 4

Author(s):

Majid Valizadeh ◽

Alireza Shirazi ◽

Pantea Izadi ◽

Javad Tavakkoli Bazzaz ◽

Hamed Rezaeejam ◽

...

Keyword(s):

Ionizing Radiation ◽

Peripheral Blood ◽

Double Strand Breaks ◽

Dna Double Strand Breaks ◽

Strand Breaks

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Requirement of ATM in Phosphorylation of the Human p53 Protein at Serine 15 following DNA Double-Strand Breaks

Molecular and Cellular Biology ◽

10.1128/mcb.19.4.2828 ◽

1999 ◽

Vol 19 (4) ◽

pp. 2828-2834 ◽

Cited By ~ 82

Author(s):

Kazumi Nakagawa ◽

Yoichi Taya ◽

Katsuyuki Tamai ◽

Masaru Yamaizumi

Keyword(s):

Heat Shock ◽

Ataxia Telangiectasia ◽

Xeroderma Pigmentosum ◽

P53 Protein ◽

Double Strand Breaks ◽

Nuclear Accumulation ◽

Dna Double Strand Breaks ◽

Strand Breaks ◽

Absolute Requirement ◽

Primary Fibroblasts

ABSTRACT Microinjection of the restriction endonuclease HaeIII, which causes DNA double-strand breaks with blunt ends, induces nuclear accumulation of p53 protein in normal and xeroderma pigmentosum (XP) primary fibroblasts. In contrast, this induction of p53 accumulation is not observed in ataxia telangiectasia (AT) fibroblasts. HaeIII-induced p53 protein in normal fibroblasts is phosphorylated at serine 15, as determined by immunostaining with an antibody specific for phosphorylated serine 15 of p53. This phosphorylation correlates well with p53 accumulation. Treatment with lactacystin (an inhibitor of the proteasome) or heat shock leads to similar levels of p53 accumulation in normal and AT fibroblasts, but the p53 protein lacks a phosphorylated serine 15. Following microinjection of HaeIII into lactacystin-treated normal fibroblasts, lactacystin-induced p53 protein is phosphorylated at serine 15 and stabilized even in the presence of cycloheximide. However, neither stabilization nor phosphorylation at serine 15 is observed in AT fibroblasts under the same conditions. These results indicate the significance of serine 15 phosphorylation for p53 stabilization after DNA double-strand breaks and an absolute requirement for ATM in this phosphorylation process.

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Recognition, signaling, and repair of DNA double-strand breaks produced by ionizing radiation in mammalian cells: The molecular choreography

Mutation Research/Reviews in Mutation Research ◽

10.1016/j.mrrev.2012.06.002 ◽

2012 ◽

Vol 751 (2) ◽

pp. 158-246 ◽

Cited By ~ 227

Author(s):

Larry H. Thompson

Keyword(s):

Ionizing Radiation ◽

Mammalian Cells ◽

Double Strand Breaks ◽

Dna Double Strand Breaks ◽

Strand Breaks

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

Genes ◽

10.3390/genes12091370 ◽

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.

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βarrestin-1 regulates DNA repair by acting as an E3-ubiquitin ligase adaptor for 53BP1

Cell Death and Differentiation ◽

10.1038/s41418-019-0406-6 ◽

2019 ◽

Vol 27 (4) ◽

pp. 1200-1213 ◽

Cited By ~ 1

Author(s):

Ainhoa Nieto ◽

Makoto R. Hara ◽

Victor Quereda ◽

Wayne Grant ◽

Vanessa Saunders ◽

...

Keyword(s):

Dna Damage ◽

Ionizing Radiation ◽

Ubiquitin Ligase ◽

E3 Ubiquitin Ligase ◽

Strand Break ◽

Double Strand Breaks ◽

Dna Double Strand Breaks ◽

Molecular Scaffold ◽

Strand Breaks

Abstract Cellular DNA is constantly under threat from internal and external insults, consequently multiple pathways have evolved to maintain chromosomal fidelity. Our previous studies revealed that chronic stress, mediated by continuous stimulation of the β2-adrenergic-βarrestin-1 signaling axis suppresses activity of the tumor suppressor p53 and impairs genomic integrity. In this pathway, βarrestin-1 (βarr1) acts as a molecular scaffold to promote the binding and degradation of p53 by the E3-ubiquitin ligase, MDM2. We sought to determine whether βarr1 plays additional roles in the repair of DNA damage. Here we demonstrate that in mice βarr1 interacts with p53-binding protein 1 (53BP1) with major consequences for the repair of DNA double-strand breaks. 53BP1 is a principle component of the DNA damage response, and when recruited to the site of double-strand breaks in DNA, 53BP1 plays an important role coordinating repair of these toxic lesions. Here, we report that βarr1 directs 53BP1 degradation by acting as a scaffold for the E3-ubiquitin ligase Rad18. Consequently, knockdown of βarr1 stabilizes 53BP1 augmenting the number of 53BP1 DNA damage repair foci following exposure to ionizing radiation. Accordingly, βarr1 loss leads to a marked increase in irradiation resistance both in cells and in vivo. Thus, βarr1 is an important regulator of double strand break repair, and disruption of the βarr1/53BP1 interaction offers an attractive strategy to protect cells against high levels of exposure to ionizing radiation.

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