Webster C R, Anwer M S
Department of Clinical Sciences, Tufts University School of Veterinary Medicine, North Grafton, MA 01536, USA.
Hepatology. 2001 Mar;33(3):608-15. doi: 10.1053/jhep.2001.22756.
We have previously shown that cAMP protects against hydrophobic bile acid-induced apoptosis in cultured rat hepatocytes through pathways dependent on activation of phosphoinositide 3-kinase and inhibition of mitogen activated protein kinase. Hepatocyte growth factor protects epithelial cells against apoptosis and activates both of these kinases in hepatocytes. We studied the effect of hepatocyte growth factor on glycochenodeoxycholate-induced apoptosis to determine whether hepatocyte growth factor protects hepatocytes against bile acid-induced apoptosis and whether the protective effect is mediated via phosphoinositide 3-kinase and/or mitogen-activated protein kinase pathways. Two-hour exposure of cultured rat hepatocytes to glycochenodeoxycholate resulted in apoptosis in 12.5 +/- 0.49% of the cells. Pretreatment with hepatocyte growth factor (50 ng/mL) decreased apoptosis by 50% to 70%. Hepatocyte growth factor cytoprotection was prevented by pretreatment with the phosphoinositide 3-kinase inhibitors, wortmannin (50 nmol/L) or Ly 294002 (40 micromol/L). Hepatocyte growth factor activated phosphoinositide 3-kinase dependent protein kinase B and mitogen-activated protein kinase. Pretreatment of hepatocytes with a mitogen-activated protein kinase inhibitor, U0126 (40 micromol/L) or an inhibitor of pp70(s6) kinase, rapamycin (100 nmol/L), had no effect on the growth factor's anti-apopotic effect. Treatment with hepatocyte growth factor resulted in mitogen-activated protein kinase-dependent phosphorylation of BAD on serine(112). In summary, hepatocyte growth factor protection against bile acid-induced apoptosis occurs via a phosphoinositide 3-kinase pathway and is not dependent on the mitogen-activated protein kinase pathway, phosphorylation of BAD on serine(112), or activation of p70(S6) kinase.
我们之前已经表明，环磷酸腺苷（cAMP）通过依赖磷脂酰肌醇3激酶激活和丝裂原活化蛋白激酶抑制的途径，保护培养的大鼠肝细胞免受疏水性胆汁酸诱导的凋亡。肝细胞生长因子保护上皮细胞免受凋亡，并在肝细胞中激活这两种激酶。我们研究了肝细胞生长因子对甘氨鹅脱氧胆酸盐诱导的凋亡的影响，以确定肝细胞生长因子是否保护肝细胞免受胆汁酸诱导的凋亡，以及这种保护作用是否通过磷脂酰肌醇3激酶和/或丝裂原活化蛋白激酶途径介导。将培养的大鼠肝细胞暴露于甘氨鹅脱氧胆酸盐两小时，导致12.5±0.49%的细胞发生凋亡。用肝细胞生长因子（50 ng/mL）预处理可使凋亡减少50%至70%。用磷脂酰肌醇3激酶抑制剂渥曼青霉素（50 nmol/L）或LY294002（40 μmol/L）预处理可阻止肝细胞生长因子的细胞保护作用。肝细胞生长因子激活了依赖磷脂酰肌醇3激酶的蛋白激酶B和丝裂原活化蛋白激酶。用丝裂原活化蛋白激酶抑制剂U0126（40 μmol/L）或pp70（s6）激酶抑制剂雷帕霉素（100 nmol/L）预处理肝细胞，对生长因子的抗凋亡作用没有影响。用肝细胞生长因子处理导致BAD在丝氨酸（112）上发生丝裂原活化蛋白激酶依赖性磷酸化。总之，肝细胞生长因子对胆汁酸诱导的凋亡的保护作用通过磷脂酰肌醇3激酶途径发生，不依赖于丝裂原活化蛋白激酶途径、BAD在丝氨酸（112）上的磷酸化或p70（S6）激酶的激活。
