蛋白激酶C及转化生长因子β1信号通路对肝星状细胞激活的影响

目的探讨蛋白激酶C（PKC）活性改变对HSC表达TGF β1的影响及在HSC激活中的作用。方法将肝星状细胞系rHSC-99分为3组：对照组（A组），PKC激动剂佛波酯0．5μmol／L组（B组），PKC抑制剂Calphostin C 100nmol／L组（C组）。加药后0、3、6、12h和24h分别检测各组细胞PKC活性的变化；作用24h后，采用Western blot和RT—PCR方法检测各组细胞TGF β1，Smad 4，Ⅰ、Ⅲ型胶原和α-平滑肌肌动蛋白的表达；采用MTT法检测细胞的增殖情况。结果 佛波酯作用后PKC的活性显著增强，而Calphostin C则抑制PKC的活性。PKC活性增强后，与对照组相比TGF β1及其下游信号分子Smad 4的表达分别升高了4．8倍和13．1倍（P〈0．01）；HSC的Ⅰ、Ⅲ型胶原和α-平滑肌肌动蛋白的表达分别升高了2．4倍、1．8倍和1．3倍（P〈0．01），并促进HSC的增殖；PKC活性被抑制后则能抑制以上作用。结论PKC活性的改变能调控HSC中TGF β1的表达，在HSC的激活中发挥调节作用。

Effect of protein kinase C/transforming growth factor beta 1 pathway on activation of hepatic stellate cells

OBJECTIVE: To investigate the effect of protein kinase C (PKC)/transforming growth factor beta 1 (TGF beta1) pathway on activation of hepatic stellate cells (HSC). METHODS: HSC rHSC-99 cell line was used in three groups in this study. Group A served as a control. In group B the HSC were incubated with PKC agonist PMA (0.5 micromol/L), and in group C the cells were incubated with PKC inhibitor calphostin C (100 nmol/L). The PKC activities were detected at different incubation time points (0, 3, 6, 12 and 24 h). Western blot and RT-PCR were used to detect the expression of TGF beta1, Smad 4, collagen type I, III and alpha-smooth muscle actin (alpha-SMA) at the 24 h point. Cell proliferation was assessed by MTT colorimetric assay. RESULTS: PMA increased the activity of PKC significantly, whereas calphostin C inhibited the activity of PKC. The increased activity of PKC promoted the HSC to express TGF beta1, Smad 4, collagen type I, III and alpha-SMA. In comparison with the controls, the expressions of TGF beta1, Smad 4, collagen type I, III and alpha-SMA increased 4.8, 13.1, 2.4, 1.8 and 1.3 fold respectively (P < 0.01). PKC promoted the proliferation of HSC. The above effects were inhibited by the inhibition of PKC activity. CONCLUSION: Changing of PKC activity can regulate and control the expression of TGF beta1, which may play a role in regulating the activation of HSC.