Homozygous mutation of MTPAP causes cellular radiosensitivity and persistent DNA double-strand breaks.
Homozygous mutation of MTPAP causes cellular radiosensitivity and persistent DNA double-strand breaks.
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DOI：
10.1038/cddis.2014.99
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发表时间：
2014-03-20
影响因子：
9
通讯作者：
中科院分区：
文献类型：
--
作者：
对以放射敏感性为特征的罕见人类综合征的研究有助于识别与电离辐射 DNA 损伤反应有关的新型蛋白质和途径。在本研究中，通过外显子组测序鉴定出线粒体多聚腺苷酸聚合酶（MTPAP）中的突变，该突变以前未被认识到其在 DNA 损伤反应中的作用，并随后与细胞放射敏感性相关。来自两名具有纯合 MTPAP 错义突变的患者的细胞系对放射敏感，并且可以通过将野生型 mtPAP cDNA 转染到 mtPAP 缺陷细胞系中来消除这种放射敏感性。对细胞表型的进一步分析揭示了 DNA 修复延迟、DNA 双链断裂水平增加、活性氧 (ROS) 增加以及辐射 (IR) 后细胞死亡增加。用强效抗氧化剂 α-硫辛酸和 n-乙酰半胱氨酸对细胞进行预红外处理，足以消除 DNA 修复和克隆存活缺陷。我们的结果证实，MTPAP 基因的突变会导致细胞表型增加 DNA 损伤、减少修复动力学、增加细胞凋亡死亡以及暴露于电离辐射后克隆存活率降低，这表明发病机制涉及 ROS 稳态的破坏。
The study of rare human syndromes characterized by radiosensitivity has been instrumental in identifying novel proteins and pathways involved in DNA damage responses to ionizing radiation. In the present study, a mutation in mitochondrial poly-A-polymerase (MTPAP), not previously recognized for its role in the DNA damage response, was identified by exome sequencing and subsequently associated with cellular radiosensitivity. Cell lines derived from two patients with the homozygous MTPAP missense mutation were radiosensitive, and this radiosensitivity could be abrogated by transfection of wild-type mtPAP cDNA into mtPAP-deficient cell lines. Further analysis of the cellular phenotype revealed delayed DNA repair, increased levels of DNA double-strand breaks, increased reactive oxygen species (ROS), and increased cell death after irradiation (IR). Pre-IR treatment of cells with the potent anti-oxidants, α-lipoic acid and n-acetylcysteine, was sufficient to abrogate the DNA repair and clonogenic survival defects. Our results firmly establish that mutation of the MTPAP gene results in a cellular phenotype of increased DNA damage, reduced repair kinetics, increased cell death by apoptosis, and reduced clonogenic survival after exposure to ionizing radiation, suggesting a pathogenesis that involves the disruption of ROS homeostasis.
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影响因子：
7.4
作者：
Gerencser, Akos A.;Neilson, Andy;Choi, Sung W.;Edman, Ursula;Yadava, Nagendra;Oh, Richard J.;Ferrick, David A.;Nicholls, David G.;Brand, Martin D.
通讯作者：
Brand, Martin D.
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作者：
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作者：
Chapman, J. Ross;Sossick, Alex J.;Jackson, Stephen P.
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影响因子：
10.5
作者：
Kitagawa, R;Bakkenist, CJ;Kastan, MB
通讯作者：
Kastan, MB
影响因子：
3.1
作者：
Gatti, RA
通讯作者：
Gatti, RA