Implication of MAPK in sodium salicylate-induced heat shock protein 27 expression in human lens eplthelial Cells in vitro

Abstract

Background Heat shock proteins (HSPs) are highly conserved proteins that are induced in cells when confronted with a wide variety of proteotoxic stresses.HSP27 has a high degree of similarity with α-crystallin protein.The abnormality of HSP27 structure and expression are closely related to the formation of cataracts.Our previous study showed sodium salieylate has the protective effect on H2O2-induced lens damage.Objective This study was to investigate the roles of MAPK signal pathway in sodium salicylate-induced the expression of HSP27 in human lens epithelial cells (LECs) in vitro.Methods Human LECs were incubated in the fresh media containing sodium salicylate at different concentrations (0-55 mmol/L) for different times (1-5 hours) and allowed to be recovered in fresh medium without sodium salicylate for 1-24 hours with or without pretreatment with P38MAPK inhibitor (SB203580), ERK1/2 inhibitor (PD98059) and JNK/SAPK inhibitor ( SP600125). The expressions of P38MAPK, EBK1/2, JNK/SAPK, phosphorylated P38MAPK, phosphorylated ERK1/2, phosphorylated JNK/SAPK and HSP27 were detected by Western blot. HSP27 mRNA was detected by RT-PCR. The expression of HSP27 was also detected by immunohistochemistry. Results There was only weak expression of HSP27 in normal human LECs.After stimulation of 35-55 mmol/L sodium salicylate was removed and human LECs were cultured again for 6 hours,the expression of HSP27 in LECs were significantly increased ( F= 509. 953,P<0. 01). HSP27 was absent expressed in human LECs in 55 mmol/L sodium salicylate stimulation for 1-5 hours groups, but LECs were re-cultured for 3,6 hours after removed the stimulation, the expression of HSP27 was elevated (F = 452. 534, P<0. 01). Activation of P38 M APK occurred after sodium salicylate stimulation 30 minutes and 1 hour ( F = 865.68, P<0. 01). However, ERK 1/2 was expressed after sodium salicylate was eliminated for 1-6 hours ( F = 388.84, P<0. 01). JNK/SAPK was inactived by sodium salicylate. The expression of HSP27 could be down-regulated with the pretreatment of SB203580 and PD98059. Conclusion Sodium salicylatc can induce the expression of HSP27 in human (LECs) . The effects are mediated,at least in part ,through the activation of P38MAPK and ERK1/2 signaling pathway . Key words: Sodium salicylate; Human lens epithelial cells; Mitogen-activated protein kinase; Heat shock proteins