Effects of the overexpression of the small heat shock protein, HSP27, on the sensitivity of human fibroblast cells exposed to oxidative stress.
The role of the human small heat shock protein (HSP27) in oxidative stress was examined using stable transformants of an immortalized human fibroblast cell line (KMST-6) isolated by transfection of HSP27 expression vectors. Several stable transformants that expressed high or low levels of HSP27 protein were obtained. Clones expressing high levels of HSP27 were more sensitive to growth inhibition by a low dose of hydrogen peroxide (0.1 mM) than those expressing low levels. Clones expressing high levels of HSP27 did not acquire obvious resistance to hyperthermy and cytotoxic agents, except for one (#13), in which resistance to cytotoxic agents was increased. The level of phosphorylated HSP27 in clones expressing high levels of this protein increased at 30 min and was sustained even 4 hours after exposing the cells to 0.1 mM of hydrogen peroxide. On the other hand, the levels in clones expressing low levels of HSP27 were reduced within 4 hours after exposure to hydrogen peroxide. Furthermore, overexpression of nonphosphorylatable mutant HSP27 did not affect sensitivity to oxidative stress. These results suggested that constitutively high expression of HSP27 in KMST-6 cells make them susceptible to oxidative stress resulting in growth arrest, and this mechanism could involve the phosphorylation of HSP27.
Arata
S
S
Department of Microbiology, School of Pharmaceutical Sciences, Showa University, Tokyo, Japan.
Hamaguchi
S
S
Nose
K
K
D002461:Cell Line, Transformed; D003609:Dactinomycin / Q000494:pharmacology; D004317:Doxorubicin / Q000494:pharmacology; D004351:Drug Resistance; D005347:Fibroblasts / Q000187:drug effects / Q000502:physiology*; D006360:Heat-Shock Proteins / Q000378:metabolism*; D006358:Hot Temperature; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D018384:Oxidative Stress; D010766:Phosphorylation; D013234:Stem Cells / Q000187:drug effects; D014162:Transfection
D006360:Heat-Shock Proteins; D003609:Dactinomycin; D004317:Doxorubicin; D006861:Hydrogen Peroxide