[The role of FAK-ERK signal transduction pathway in apoptosis of hepatic stellate cell].

OBJECTIVES

To investigate the effects of FAK-related non-kinase (FRNK) on the apoptosis of hepatic stellate cells (HSC) in vitro and on the extracellular signal-regulated kinase (ERK) signal transduction pathway.

METHODS

HSC were stimulated by fibronectin (FN), and then they were transfected with FAK-related non-kinase (FRNK) plasmids mediated by cationic liposome. The apoptosis of FRNK-induced HSC was examined by annexin-V/propidium iodide double-labeled flow cytometry (FCM), gel electrophoresis and transmission electron microscopy. Levels of FRNK, FAK, p-FAK (Tyr397), ERK1 and p-ERK in HSC were assayed by Western blot on the protein level, and by RT-PCR on the mRNA level.

RESULTS

The expression of FRNK was enhanced after FRNK plasmids were transiently transfected into the HSC. The apoptotic rate of the HSC exposed to FRNK plasmids for 48 h was higher than that in the non-FRNK plasmid group (25.37%+/-1.92% vs 9.28%+/-1.05%, P less than 0.01), and was accompanied by a significantly higher activity of caspase-3 both in the protein and in the mRNA levels [(264.17+/-12.60 vs 185.82+/-9.69), P less than 0.01; (4.19+/-0.48 vs 1.07+/-0.27), P less than 0.01]. After exposure of HSC to FRNK plasmids, compared with the non-FRNK plasmid group, the expressions of p-FAK, ERK1 and p-ERK in protein and mRNA levels were lower; on the contrary, compared with the control group, the expressions of p-FAK, ERK1 and p-ERK in the FN group were higher.

CONCLUSION

The expression of FRNK was enhanced and the phosphorylation of FAK was inhibited after FRNK was transiently transfected into HSC in vitro. FRNK induces apoptosis of HSC. FAK-ERK signal transduction pathway perhaps is involved in the process.