肝星形细胞中细胞凋亡和存活的信号调控

肝星状细胞(hepatic stellate cells,HSCs)在肝脏纤维化发生过程中起着关键作用.当正常肝脏受到损伤时,HSCs由静息状态转分化为类肌成纤维细胞,并保持这种处于激活状态的表型,它们接收到的凋亡和存活的生物信号将决定激活态HSCs的最终细胞寿命.HSCs凋亡的发生与一系列复杂而又相互关联的生物信号传导和调控有关,HSCs凋亡信号来自于细胞膜受体,如死亡受体、神经生长因子受体和外周型苯甲二氮卓受体(peripheral-type benzodiazepine receptor);以及胞浆蛋白,如Bcl-2家族蛋白和细胞周期蛋白等.HSCs存活信号受到多种激酶和细胞因子的诱导,如金属蛋白酶组织抑制剂-1(tissue jnhibitors of metalloproteinase-1)、Rho/Rho激酶、血小板源生长因子(platelet-derived growth factor)、转化生长因子-β1(transforming growth factor-β1)和胰岛素样生长因子(insulin-like growth factor-1)等.特异性地诱导HSCs发生凋亡是治疗肝脏纤维化的直接和有效手段,虽然目前对HSCs由激活态到静息状态的转归尚需进一步研究,但诱导HSCs凋亡将是治疗肝脏纤维化和肝硬化的研究热点和主要发展方向.

Apoptotic and survival signals in hepatic stellate cells

Hepatic stellate cells (HSCs) play an important role in hepatic fibrogenesis. In response to liver injury, HSCs undergo a process called activation, which involves 2 stepsjinitiation from quiescent phenotype to myofibroblast-like phenotype, and perpetuation that maintains the activated phenotype of HSCs. The fate of the activated HSCs depends on the apoptotic and survival signals that they receive. The apoptosis of HSCs results from a series of complex and interrelated signaling events. Apoptotic signals for the activated HSCs include proteins from membrane receptors, such as death receptors, nerve growth factor receptor and peripheral-type benzodiazepine receptor, as well as proteins from cytoplasm such as Bcl-2 family members. The survival signals for the activated HSCs are induced by some kinases and cytokines including tissue inhibitors of metalloproteinase-1, Rho/Rho kinase, platelet-derived growth factor, transforming growth factor beta-1, and insulin-like growth factor-1. Approaches that specifically initiate HSC apoptosis are promising to be direct and effective strategies to treat liver fibrosis. Although it remains unclear whether the activated HSCs could be reversed back to the quiescent phenotype, the different expression and sensitivity of pro-apoptotic and survival molecules between quiescent and activated HSCs provide a prospect to develop therapeutic approaches that specifically targets apoptosis of the activated HSCs. These therapeutic strategies to induce HSC apoptosis are current research hotspot and the future for the patients with liver fibrosis and cirrhosis.