Document Detail


Constitutive histone H2AX phosphorylation on Ser-139 in cells untreated by genotoxic agents is cell-cycle phase specific and attenuated by scavenging reactive oxygen species.
MedLine Citation:
PMID:  16820894     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
DNA damage, particularly when it involves formation of double-strand breaks (DSBs), triggers phosphorylation of histone H2AX on Ser-139. Phosphorylated H2AX has been named gammaH2AX, and induction of gammaH2AX in cells exposed to genotoxic agents is considered a sensitive and specific reporter of DNA damage. However, in untreated normal cells as well in the cells of various tumor lines cells, a fraction of histone H2AX molecules remain phosphorylated. In the present study, we observed that the extent of this constitutive H2AX phosphorylation varies depending on the cell type (line) and on cell cycle phase and, in most cell types, S and G(2)/M phase cells exhibit greater levels of H2AX phosphorylation than do cells in the G(1) phase. Furthermore, constitutive H2AX phosphorylation in human pulmonary carcinoma A549, lymphoblastoid TK6, and in normal bronchial epithelial cells was reduced following cell exposure to N-acetyl-L-cysteine, a scavenger of reactive oxygen intermediates; the reduction was most pronounced for G(2)M cells. Growth of A549 cells in the presence of buthionine sulfoximine, an inhibitor of glutathione synthetase, amplified the level of constitutive H2AX phosphorylation in A549 cells. The observed constitutive H2AX phosphorylation may be a reflection of the ongoing DNA damage mediated by reactive oxygen species (ROS) generated by metabolic activity during progression through the cell cycle, leading to formation of DSBs during the S phase. Because cumulative DNA damage in proliferating cells mediated by ROS is considered the key mechanism for cell ageing, the present approach to estimate the degree of attenuation of constitutive H2AX phosphorylation by antioxidants may provide a convenient tool to assess the DNA-protective and possible anti-ageing properties of other agents.
Authors:
Xuan Huang; Toshiki Tanaka; Akira Kurose; Frank Traganos; Zbigniew Darzynkiewicz
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural    
Journal Detail:
Title:  International journal of oncology     Volume:  29     ISSN:  1019-6439     ISO Abbreviation:  Int. J. Oncol.     Publication Date:  2006 Aug 
Date Detail:
Created Date:  2006-07-05     Completed Date:  2006-12-14     Revised Date:  2010-12-03    
Medline Journal Info:
Nlm Unique ID:  9306042     Medline TA:  Int J Oncol     Country:  Greece    
Other Details:
Languages:  eng     Pagination:  495-501     Citation Subset:  IM    
Affiliation:
Brander Cancer Research Institute, New York Medical College, Valhalla, NY 10595, USA.
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MeSH Terms
Descriptor/Qualifier:
Antineoplastic Agents / pharmacology
Antioxidants / metabolism
Cell Aging
Cell Cycle
Cell Line, Tumor
Free Radical Scavengers / pharmacology*
Glutathione / chemistry
Histones / chemistry*
Humans
Jurkat Cells
Phosphorylation
Reactive Oxygen Species
Serine / chemistry*
Grant Support
ID/Acronym/Agency:
CA 28704/CA/NCI NIH HHS; R01 CA028704-27/CA/NCI NIH HHS
Chemical
Reg. No./Substance:
0/Antineoplastic Agents; 0/Antioxidants; 0/Free Radical Scavengers; 0/H2AFX protein, human; 0/Histones; 0/Reactive Oxygen Species; 56-45-1/Serine; 70-18-8/Glutathione

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