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Influence of reduced glutathione on end-joining of DNA double-strand breaks: Cytogenetical and molecular approach

Ghoshal, Nitin and Sharma, Sheetal and Banerjee, Atanu and Kurkalang, Sillarine and Raghavan, Sathees C and Chatterjee, Anupam (2017) Influence of reduced glutathione on end-joining of DNA double-strand breaks: Cytogenetical and molecular approach. In: MUTATION RESEARCH-FUNDAMENTAL AND MOLECULAR MECHANISMS OF MUTAGENESIS, 795 . pp. 1-9.

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Official URL: http://dx.doi.org/10.1016/j.mrfmmm.2016.10.005


Radiation induced DNA double-strand breaks (DSB) are the major initial lesions whose misrejoining may lead to exchange aberrations. However, the role of glutathione (GSH), a major cellular thiol, in regulating cell's sensitivity to DNA damaging agents is not well understood. Influence of endogenous GSH on the efficiency of X-rays and bleomycin (Blem) induced DNA DSBs end joining has been tested here cytogenetically, in human lymphocytes and Hct116 cells. In another approach, oligomeric DNA (75 bp) containing 5'-compatible and non-compatible overhangs mimicking the endogenous DSB were for rejoining in presence of cell-free extracts from cells having different endogenous GSH levels. Frequency of aberrations, particularly exchange aberrations, was significantly increased when Blem was combined with radiation. The exchange aberration frequency was further enhanced when combined treatment was given at 4 degrees C since DNA lesions are poorly repaired at 4 degrees C so that a higher number of DNA breaks persist and interact when shifted from 4 degrees C to 37 degrees C. The exchange aberrations increased further when the combined treatment was given to Glutathione-ester (GE) pre-treated cells, indicating more frequent rejoining of DNA lesions in presence of higher cellular GSH. This is further supported by the drastic reduction in frequency of exchange aberrations but significant increase in incidences of deletions when combined treatment was given to GSH-depleted cells. End-joining efficiency of DNA DSBs with compatible ends was better than for non-compatible ends. End-joining efficiency of testicular and MCF7 cell extracts was better than that of lungs and Hct116 cells. Cell extract made from GE-treated MCF-7 cells provided more efficient end-joining than from untreated and GSH-depleted cells. However, direct addition of GSH to the cell-free extracts showed considerable reduction in end joining efficiency. Present data indicate that higher endogenous GSH favours rejoining of DNA DSBs (both restitution and illegitimate reunion) which in turn produce more exchange aberrations. (C) 2016 Elsevier B.V. All rights reserved.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the ELSEVIER SCIENCE BV, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS
Department/Centre: Division of Biological Sciences > Biochemistry
Date Deposited: 03 Apr 2017 04:50
Last Modified: 03 Apr 2017 04:50
URI: http://eprints.iisc.ac.in/id/eprint/56456

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