P37 Role of endoplasmic reticulum stress in the regulation endogenous hydrogen sulfide for hepatocyte apoptosis induced by LPS

Abstract

The study was carried out to investigate the role of endoplasmic reticulum stress (ERS) in regulation of endogenous hydrogen sulfide (H2S) for hepatocyte apoptosis induced by lipopolysaccharide (LPS). The cultured rat hepatocyte line BRL cells were treated with LPS and ERS inducer thapsigargin (TG), ERS inhibitor 4-phenylbutyric acid (4-PBA) respectively or in a different combination manner. RNA interference technique was used to silence the expression of CBS and CSE. H2S level, cell viability and apoptosis rate were measured. The expressions of CBS and CSE mRNA and protein, GRP78,CHOP, caspase-12 and caspase-3 were detected with RT-PCR and Western blotting. Compared with vehicle, LPS caused a decrease in cell viability, an increase in apoptosis rate and significantly increased expression of GRP78 protein in a dose- and time-dependent manner. Almost similar increases were observed in expression of CHOP,caspase-12 and caspase-3 proteins. TG led to a marked decrease in cell viability and an increase in apoptosis rate. Furthermore, TG exacerbated while 4-PBA alleviated LPS-induced hepatocyte injuries. LPS induced a up-regulation of CBS-H2S and CSE-H2S systems. Both of CBS siRNA and CSE siRNA reversed the increased endogenous H2S formation and up-regulation of CBS and CSE expressions, inhibited the decreased cell viability and increased apoptosis rate and obviously decreased expressions of GRP78, CHOP, caspase-12, caspase-3 induced by LPS. Results showed that endogenous H2S can aggravate LPS-induced hepatocyte apoptosis through enhancement of ERS.