Adachi T, Nakashima S, Saji S, Nakamura T, Nozawa Y
Second Department of Surgery, Gifu University School of Medicine, Japan.
Hepatology. 1996 Nov;24(5):1274-81. doi: 10.1053/jhep.1996.v24.pm0008903410.
Hepatocyte growth factor (HGF) activated phospholipase D (PLD) in primary-cultured rat hepatocytes, as assessed by the formation of phosphatidylbutanol (PBut), a specific and stable product of PLD activity in the presence of 0.3% butanol. PLD hydrolyzes phosphatidylcholine to choline and phosphatidic acid (PA), which is further metabolized to diacylglycerol (DG) by PA phosphohydrolase (PAP). In HGF-stimulated hepatocytes, butanol prevented the formation of PA and DG. A PAP inhibitor, propranolol, inhibited DG production with a reciprocal increase of PA, implying that PLD played a role in the formation of not only PA but DG. Inhibitors for protein kinase C (PKC), Ro31-8425, H-7, and calphostin C, reduced HGF-induced PLD activation. A protein tyrosine kinase (PTK) inhibitor, genistein but not its inactive analogue daidzein, inhibited PLD activation by HGF. Moreover, depletion of extracellular Ca2+ by omission of Ca2+ or by chelating residual Ca2+ with ethyleneglycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) abolished HGF-induced PLD activation. HGF, phorbol myristate acetate (PMA) and a DG analog, oleylacetylglycerol (OAG), activated the expression of c-jun and c-fos messenger RNAs (mRNAs). Ro31-8425, calphostin C, and genistein, which prevented HGF-induced PLD activation, inhibited induction of these immediate early genes. Butanol and propranolol at concentrations which effectively inhibited the formation of DG, suppressed HGF-induced expression of c-jun and c-fos mRNAs. However, HGF-induced mitogen-activated protein kinase (MAPK) activation was not affected by both butanol and propranolol. These results suggest that PTK, PKC, and Ca2+ regulate HGF-induced PLD activation, and that DG produced by PLD pathway may play a role in the induction of immediate early genes, which is activated in MAPK-independent manner, in rat hepatocytes.
肝细胞生长因子（HGF）可激活原代培养大鼠肝细胞中的磷脂酶D（PLD），这是通过磷脂丁醇（PBut）的形成来评估的，PBut是在0.3%丁醇存在下PLD活性的一种特异性且稳定的产物。PLD将磷脂酰胆碱水解为胆碱和磷脂酸（PA），PA再由PA磷酸水解酶（PAP）进一步代谢为二酰基甘油（DG）。在HGF刺激的肝细胞中，丁醇可阻止PA和DG的形成。一种PAP抑制剂普萘洛尔可抑制DG的产生，同时PA会相应增加，这意味着PLD不仅在PA的形成中起作用，在DG的形成中也起作用。蛋白激酶C（PKC）抑制剂Ro31 - 8425、H - 7和钙泊三醇C可降低HGF诱导的PLD激活。一种蛋白酪氨酸激酶（PTK）抑制剂染料木黄酮可抑制HGF诱导的PLD激活，而其无活性类似物大豆苷元则无此作用。此外，通过省略Ca2+或用乙二醇双（β - 氨基乙基醚）- N，N，N'，N'-四乙酸（EGTA）螯合残留的Ca2+来耗尽细胞外Ca2+，可消除HGF诱导的PLD激活。HGF、佛波酯（PMA）和一种DG类似物油酰乙酰甘油（OAG）可激活c - jun和c - fos信使核糖核酸（mRNA）的表达。Ro31 - 8425、钙泊三醇C和染料木黄酮可阻止HGF诱导的PLD激活，它们也抑制这些即刻早期基因的诱导。丁醇和普萘洛尔在有效抑制DG形成的浓度下，可抑制HGF诱导的c - jun和c - fos mRNA的表达。然而，HGF诱导的丝裂原活化蛋白激酶（MAPK）激活不受丁醇和普萘洛尔的影响。这些结果表明，PTK、PKC和Ca2+调节HGF诱导的PLD激活，并且PLD途径产生 的DG可能在即刻早期基因的诱导中起作用，在大鼠肝细胞中，这种诱导是以不依赖MAPK的方式激活的。
