Hepatocyte growth factor promotes renal epithelial cell survival by dual mechanisms
Hepatocyte growth factor promotes renal epithelial cell survival by dual mechanisms
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DOI：
10.1152/ajprenal.1999.277.4.f624
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发表时间：
1999-10-01
影响因子：
4.2
通讯作者：
Liu, YH
中科院分区：
文献类型：
--
作者：
Liu, YH
肝细胞生长因子（HGF）具有保护肾上皮细胞免于凋亡的作用。为了明确HGF抑制细胞凋亡的机制，我们研究了HGF对Bcl-2家族蛋白磷酸化和表达的影响。以人近端小管上皮细胞（HKC）系为模型，我们证明了HGF的组成性表达对血清戒断诱导的凋亡性死亡具有明显的抗性。HGF诱导HKC细胞中Akt的快速磷酸化，紧接着是Bcl-2家族中促凋亡成员Bad的磷酸化和失活。10 nM wortmannin预处理HKC细胞完全消除hgf诱导的Akt和Bad磷酸化，提示该途径依赖于磷酸肌苷（PT） 3-激酶。Bad的过表达增加了野生型hc细胞的凋亡死亡，而在产生hgf的H4细胞中没有。免疫印迹证实，在H4细胞中过表达的Bad蛋白在Ser（112）和Ser（136）位点被完全磷酸化。与HGF长期孵育的HKC细胞也显著诱导Bcl-xL的表达，Bcl-xL是Bcl-2家族的抗凋亡成员。这些结果表明，HGF在肾上皮细胞中的抗凋亡作用是通过两种不同的Bcl-2家族蛋白的双重机制介导的。HGF通过PI 3-激酶/Akt通路触发Bad磷酸化，从而使该促凋亡蛋白失活，同时诱导抗凋亡Bcl-xL的表达。
Hepatocyte growth factor (HGF) has been shown to protect renal epithelial cells against apoptosis. To define the mechanism by which HGF inhibits apoptosis, we investigated the effect of HGF on the phosphorylation and expression of the Bcl-2 family proteins. Using a human proximal tubular epithelial cell (HKC) line as a model, ave demonstrated that constitutive expression of HGF conveyed marked resistance to apoptotic death induced by serum withdrawal. HGF induced rapid phosphorylation of Akt in HKC cells, which was immediately followed by phosphorylation and resultant inactivation of Bad, a pro-apoptotic member of the Bcl-2 family. Pretreatment of the HKC cells with 10 nM wortmannin completely abolished HGF-induced phosphorylation of Akt and Bad, suggesting that this pathway is dependent on phosphoinositide (PT) 3-kinase. Overexpression of Bad increased apoptotic death in wild-type HKC cells but not in HGF-producing H4 cells. Immunoblotting confirmed that the Bad protein overexpressed in H4 cells was fully phosphorylated at both Ser(112) and Ser(136) sites. Prolonged incubation of HKC cells with HGF also dramatically induced expression of Bcl-xL, an anti-apoptotic member of the Bcl-2 family. These results suggest that the anti-apoptotic effect of HGF in renal epithelial cells is mediated by dual mechanisms involving two distinct Bcl-2 family proteins. HGF triggers Bad phosphorylation via the PI 3-kinase/Akt pathway, thereby inactivating this pro-apoptotic protein, while simultaneously inducing expression of anti-apoptotic Bcl-xL.