科研之友
微信
新浪微博
Facebook
分享链接
摘要
Induction of the heat shock response (HSR), determined by hsp70-luciferase reporter and HSP70 protein expression, is attenuated as a function of age of the IMR-90 human diploid fibroblasts. To better understand the underlying mechanism, we evaluated changes in the regulation and function of the HSF1 transcription factor. We show that the activation of HSF1 both in vivo and in vitro was decreased as a function of age, and this was attributable to a change in the regulation of HSF1;is the abundance of HSF1 protein and mRNA was unaffected. HSF1 was primarily cytosolic in young cells maintained at 37 degrees C, and heat shock promoted its quantitative nuclear translocation and trimerization. In old cells, some HSF1 was nuclear sequestered at 37 degrees C, and heat shock failed to promote the quantitative trimerization of HSF1. These changes in HSF1 could be reproduced by treating young cells with H(2)O(2) to stunt them into premature senescence. Flow cytometry measurement of peroxide content showed higher levels in old cells and H(2)O(2)-induced premature senescent cells as compared to young cells. Experiments using isoelectric focusing and Western blot showed age-dependent changes in the mobility of HSF1 in a pattern consistent with its S-glutathiolation and S-nitrosylation; these changes could be mimicked by treating young cells with H(2)O(2). Our results demonstrated dynamic age-dependent changes in the regulation but not the amount of HSF1. These changes are likely mediated by oxidative events that promote reversible and irreversible modification of HSF1 including S-glutathiolation and S-nitrosylation. J. Cell. Biochem. 106: 267-278, 2009.
- 出版日期2009-2-1
