Lovastatin 및 Isoprenylation 억제제에 의한 배양한 백서 사구체 혈관간세포의 사멸과 세포골격 변형

Abstract

Products of mevalonate pathway, such as farnesyl pyrophosphate(FPP) and geranylgeranyl pyrophospha- te(GGPP) play a critical role in protein isoprenylation. Lovastatin, which blocks mevalonate production is an isoprenylation inhibitor reported to alter cytoskeletal architecture and induce apoptosis in a variety of cell lines. Exogenous isoprenoids reversed the effects of lovastatin, suggesting the importance of isop- renoid products for cytoskeletal organization and apoptosis. The aim of this study was to define the effects of lovastatin and isoprenylation inhibitors on induction of apoptosis and cytoskeletal changes in cultured rat glomerular mesangial cells. In addition, GGPP and FPP were added exogenously with lovastatin to determine which metabolite played a more important role in apoptosis and cytoskeletal changes, respectively. Lovastatin and GGTI-286 induced changes in the degree of RhoA isoprenylation was assessed to further support the role of protein isoprenylation in apoptosis and cytoskeletal changes. The results obtained were as follows; 1) Lovastatin induced apoptosis of cultured glomerular mesangial cells in a time and dose-dependent manner independent of bcl-2. The GGPP completely reversed the proapoptotic effects of lovastatin, while FPP partially reversed it. 2) GGTI-286, a specific inhibitor of protein geranylgeranyltransferase, induced apoptosis of cultured glomerular mesangial cells in a time and dose-dependent manner similar to lovastatin. But L-744,832, a specific inhibitor of protein farnesyltransferase, did not induce apoptosis compared to control group. 3) Lovastatin and GGTI-286 induced actin stress fiber disruption, but L-744,832 failed to induce actin stress fiber disruption in cultured glomerular mesangial cells. Both GGPP and FPP completely reversed the cytoskeletal changes induced by lovastatin. 4) Cultured glomerular mesangial cells treated with lovastatin or GGTI-286 were associated with decreased isoprenylation of RhoA, a protein reported to be involved in actin cytoskeletal organization and cell survival. Such finding further supports the role of protein isoprenylation inhibition in mesangial cell apoptosis and cytoskeletal change induced by isoprenylation inhibitors. In conclusion, lovastatin and GGTI-286 induced apoptosis in cultured glomerular mesangial cells. The effect of lovastatin was completely reversed by addition of GGPP and only partially by FPP, suggesting a critical role for geranylgeranylated proteins in cultured glomerular mesangial cell apoptosis. The actin cytoskeletal change induced by lovastatin was completely reversed by addition of GGPP or FPP, sug- gesting both geranylgeranylated and farnesylated proteins are involved in actin cytoskeletal change.