Experimental Study Of C-Jun N-terminal Kinase Signaling Pathway On The Proliferation And Apoptosis Of Rat Hepatic Stellate Cells Stimulated By Acetaldehyde

Background and aimHepatic stellate cells (HSC) have been considered as the unequivocal source of extracellular matrix in liver fibrosis. In recent years, how the signal transduction in HSC regulate has been still remained in radical debate. It was found in the research on alcoholic liver diseaes that acetaldehyde has regulating effect on HSC proliferation as a kind of stimulating signal, which is the key molecule in the pathogenesis of alcoholic liver disease. c-Jun N-terminal kinase(JNK)pathway is involves in multiple physiological processes, such as cell growth, development and function synchronization among the cells , and apoptosis. Our previous research has known ERK (extracellular signal-regulated kinase) signaling pathway play an important role in proliferation of HSC stimulated by acetaldehyde, however, the molecular mechanism which JNK regulates HSC proliferation and apoptosis has not been well known. The effect of JNK pathway in liver fibrosis reported was very little: Now severy researching showed that hepatic cells proliferation and type I collagen synthesis of HSCs is related to JNK signal transduction pathway, we sought to investigate the effect of SP600125 on phosphorylated-JNK (p-JNK), cell proliferation, and apoptosis in rat hepatic stellate cells stimulated by acetaldehyde, so that the theoretical and experimental data can be offered for clinical therapy of liver fibrosis. Materials and MethodsRat hepatic stellate cells was cultured in vitro. HSC, pre-disposed in different dose SP600125 (20,60,100ng/ml), then stimulated by acetaldehyde, were collected for detection of the level of the p-JNK, the changes of the proliferation, cell cycle, and apoptosis by means of western blot, MTT, immunohistochemistry stain, agarose gel eletrophoresis of DNA fragmentationand flow cytometry.. Main Results(1) The cells proliferation, p-JNK level, were enhanced apparently after HSC were stimulated by acetaldehyde. GO/G1-S phase transition was also accelerated in HSC stimulated by acetaldehyde. The difference has statistical significant between experimental group and control group (P<0.05).(2) The SP600125 with the concentration of 20, 60ng/ml and 100ng/ml could significantly inhibit p-JNK level in HSC and HSC proliferation stimulated by acetaldehyde (P<0.05). The inhibition of SP600125 with the concentration of 20 ng/ml on the HSC proliferation were not significant (P>0.05). The SP600125 with the concentration of 60 ng/ml and 100 ng/ml could significantly inhibit GO/G1-S phase transition of the HSC stimulated by acetaldehyde(P<0.05).(3) The SP600125 with the concentration of 60,100ng/ml show DNA ladder on agarose gel eletrophoresis of DNA fragmentation; the SP600125 at different concentration (20,60,100ng/ml) could increase apoptosis of HSC, The difference has statistical significant between experimental group and control group (P<0.05).Main Conclusions(1) JNK could be activated significantly after HSC were stimulated by acetaldehyde.(2) HSC proliferation stimulated by acetaldehyde is related to JNK signal transduction pathway.(3) The inhibitory effect on JNK binding activity might be part of the cellular mechanism of apoptosis of HSC.