Gagou, M.E., Zuazua-Villar, P. and Meuth, M. (2010) Enhanced H2AX Phosphorylation, DNA Replication Fork Arrest, and Cell Death in the Absence of Chk1. Molecular Biology of the Cell , 21 (5). pp. 739-752. ISSN 1059-1524
Abstract
H2AX phosphorylation at serine 139 (γH2AX) is a sensitive indicator of both DNA damage and DNA replication stress. Here we show that γH2AX formation is greatly enhanced in response to replication inhibitors but not ionizing radiation in HCT116 or SW480 cells depleted of Chk1. Although H2AX phosphorylation precedes the induction of apoptosis in such cells, our results suggest that cells containing γH2AX are not committed to death. γH2AX foci in these cells largely colocalize with RPA foci and their formation is dependent upon the essential replication helicase cofactor Cdc45, suggesting that H2AX phosphorylation occurs at sites of stalled forks. However Chk1-depleted cells released from replication inhibitors retain γH2AX foci and do not appear to resume replicative DNA synthesis. BrdU incorporation only occurs in a minority of Chk1-depleted cells containing γH2AX foci after release from thymidine arrest and, in cells incorporating BrdU, DNA synthesis does not occur at sites of γH2AX foci. Furthermore activated ATM and Chk2 persist in these cells. We propose that the γH2AX foci in Chk1-depleted cells may represent sites of persistent replication fork damage or abandonment that are unable to resume DNA synthesis but do not play a direct role in the Chk1 suppressed death pathway.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2010 by The American Society for Cell Biology. Reproduced in accordance with the publisher's self-archiving policy. |
Keywords: | DOUBLE-STRAND BREAKS; S-PHASE CHECKPOINT; HISTONE H2AX; TOPOISOMERASE-I; GINS COMPLEX; TUMOR-CELLS; SERINE 139; REPAIR; ATR; ACTIVATION |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Medicine, Dentistry and Health (Sheffield) > The Medical School (Sheffield) > Division of Genomic Medicine (Sheffield) > Department of Oncology and Metabolism (Sheffield) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 18 May 2017 09:13 |
Last Modified: | 18 May 2017 09:13 |
Published Version: | https://doi.org/10.1091/mbc.E09-07-0618 |
Status: | Published |
Publisher: | American Society for Cell Biology |
Refereed: | Yes |
Identification Number: | 10.1091/mbc.E09-07-0618 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:115368 |