Proteomic analysis of mycophenolic acid-induced apoptotic mechanisms in rat insulinoma cell line (RIN-5F)

Abstract

[한글]

[영문]Mycophenolic acid (MPA) is an immunosuppressive drug that has been widely used after transplantation. MPA have deleterious effects on B-cell function in vitro. Despite of B-cell toxicity of MPA, it has a critical role to prevent the islet graft rejection. The purposes of this study were to identify significant proteins associated with MPA-induces apoptosis and to evaluate the correlation between RhoGDI-a expression and activation of JNK during MPA-induced apoptosis in the insulin-secreting cell line, RIN-5F (rat insulinoma cell line) using a proteomics approach. MPA induced RIN-5F apoptosis which recovered by exogenous guanosine or GTP. 32 proteins spots with alteration more than 1.5-fold were detected in 2-dimensional gel electrophoresis in RIN-5F treated with MPA. Among those protein spots, RhoGDI-a tends to be decreased by time-dependent manner. The degenerated level of RhoGDI-a on cell death pathway induced by MPA stimulation was recovered by pre-treatment of GTP or guanosine. However, RhoGDI-a expression was not affected by pre-treatment of anti-oxidant NAC or caspase inhibitor z-VAD fmk. During cell death after treatment of MPA, the activations of MKK 4/7 and JNK were increased. JNK inhibitor (SP600125) reversed cell death ratio and prevent the reduction of RhoGDI-a expression caused by MPA. Overexpression of RhoGDI-a in RIN-5F cells by gene transfection led to significantly reduced cell apoptosis. In contrast, knock-down expression level of RhoGDI-a using siRNA accelerated MPA induced cell death. In conclusion, MPA induced apoptosis in insulin-secreting cells via down-regulation of RhoGDI-a and activation of JNK. This RhoGDI-a/JNK pathway might be the focus of therapeutic target in prevention of MPA-induced islet apoptosis.