The effects of selenium and the GPx-1 selenoprotein on the phosphorylation of H2AX

• Published in: Biochimica et biophysica acta Vol. 1830; no. 6; pp. 3399 - 3406
• Main Authors: Jerome-Morais, A., Bera, S., Rachidi, W., Gann, P.H., Diamond, A.M.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-06-2013
• Subjects: Antibiotics, Antineoplastic - pharmacology; Bleomycin - pharmacology; Cell Line, Tumor; cell viability; Checkpoint Kinase 1; Checkpoint Kinase 2; DNA Damage; DNA repair; DNA Repair - drug effects; DNA Repair - radiation effects; etiology; flow cytometry; genotoxicity; Glutathione peroxidase; Glutathione Peroxidase - genetics; Glutathione Peroxidase - metabolism; Glutathione Peroxidase GPX1; Histone H2AX; histones; Histones - genetics; Histones - metabolism; human cell lines; Humans; ionizing radiation; phosphorylation; Phosphorylation - drug effects; Phosphorylation - radiation effects; Protein Kinases - genetics; Protein Kinases - metabolism; Protein Serine-Threonine Kinases - genetics; Protein Serine-Threonine Kinases - metabolism; Radiation, Ionizing; Selenium; Selenium - metabolism; selenoproteins; Selenoproteins - genetics; Selenoproteins - metabolism; Western blotting; Glutathione peroxidase; Selenium; Histone H2AX; DNA repair
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/j.bbagen.2013.03.010

Significant data supports the health benefits of selenium although supplementation trials have yielded mixed results. GPx-1, whose levels are responsive to selenium availability, is implicated in cancer etiology by human genetic data. Selenium's ability to alter the phosphorylation of the H2AX, a histone protein that functions in the reduction of DNA damage by recruiting repair proteins to the damage site, following exposure to ionizing radiation and bleomycin was investigated.
Human cell lines that were either exposed to selenium or were transfected with a GPx-1 expression construct were exposed to ionizing radiation or bleomycin. Phosphorylation of histone H2AX was quantified by flow cytometry and survival by the MTT assay. Phosphorylation of the Chk1 and Chk2 checkpoint proteins was quantified by western blotting.
In colon-derived cells, selenium increases GPx-1 and attenuated H2AX phosphorylation following genotoxic exposures while the viability of these cells was unaffected. MCF-7 cells and transfectants that express high GPx-1 levels were exposed to ionizing radiation and bleomycin, and H2AX phosphorylation and cell viability were assessed. GPx-1 increased H2AX phosphorylation and viability following the induction of DNA damage while enhancing the levels of activated Chk1 and Chk2.
Exposure of mammalian cells to selenium can alter the DNA damage response and do so by mechanisms that are dependent and independent of its effect on GPx-1.
Selenium and GPx-1 may stimulate the repair of genotoxic DNA damage and this may account for some of the benefits attributed to selenium intake and elevated GPx-1 activity.
•Phospho-H2AX was used to assess how selenium and selenoproteins may impact DNA damage repair•GPx-1 null and expressing cells were used to evaluate effects of selenium and GPx-1 independently•Both H2AX phosphorylation and cell survival were evaluated•GPx-1 effects on the Chk1 and Chk2 DNA damage repair proteins were observed