Parmentier J H, Muthalif M M, Nishimoto A T, Malik K U
Department of Pharmacology, College of Medicine, The University of Tennessee Health Science Center, Memphis, Tennessee, USA.
Hypertension. 2001 Feb;37(2 Pt 2):623-9. doi: 10.1161/01.hyp.37.2.623.
Angiotensin II (Ang II) activates cytosolic phospholipase A(2) (cPLA(2)) and phospholipase D (PLD) in rabbit vascular smooth muscle cells (VSMCs). Ang II also activates ras/mitogen-activated protein (MAP) kinase in VSMCs; this activation is mediated by 20-hydroxyeicosatetraenoic acid (HETE) and 12(S)-HETE, which are metabolites of arachidonic acid generated by cytochrome P450 4A and lipoxygenase, respectively, produced on activation of cPLA(2). The purpose of this study was to determine if Ang II-induced PLD activation in VSMCs is mediated through the ras/extracellular signal-regulating kinase (ERK) pathway by arachidonic acid metabolites that are generated consequent to cPLA(2) stimulation. Inhibitors of PLD (C(2) ceramide), phosphatidate phosphohydrolase (propranolol), and diacylglycerol lipase (RHC 80267) attenuated Ang II-induced arachidonic acid release. Ang II-induced PLD activation, as measured by [(3)H]phosphatidylethanol production, was inhibited by C(2) ceramide but not by propranolol or RHC 80267. Ang II-induced PLD activation was decreased by the inhibitor methyl arachidonylfluorophosphate (MAFP) and the antisense oligonucleotide of cPLA(2). Inhibitors of lipoxygenases (baicalein) and cytochrome P450 4A (ODYA) attenuated Ang II-induced PLD activation. 20-HETE and 12(S)-HETE increased PLD activity. Inhibitors of ras farnesyltransferase (FPT III and BMS-191563) and MAP kinase kinase (UO126) attenuated the increase in PLD activity elicited by 20-HETE and Ang II. PLD2 was the main isoform activated by Ang II in VSMCs. These data suggest that the CYP4A metabolite 20-HETE, which is generated from arachidonic acid after cPLA(2) activation by Ang II, stimulates the ras/MAP kinase pathway, which in turn activates PLD2 and releases further arachidonic acid for prostaglandin synthesis through the phosphatidate phosphohydrolase/diacylglycerol lipase pathway.
血管紧张素 II（Ang II）可激活兔血管平滑肌细胞（VSMC）中的胞质磷脂酶 A2（cPLA2）和磷脂酶 D（PLD）。Ang II 还可激活 VSMC 中的 ras/丝裂原活化蛋白（MAP）激酶；这种激活是由 20-羟基二十碳四烯酸（HETE）和 12(S)-HETE 介导的，它们分别是细胞色素 P450 4A 和脂氧合酶产生的花生四烯酸代谢产物，在 cPLA2 激活时生成。本研究的目的是确定 Ang II 诱导的 VSMC 中 PLD 激活是否通过 cPLA2 刺激后产生的花生四烯酸代谢产物经 ras/细胞外信号调节激酶（ERK）途径介导。PLD 抑制剂（C2 神经酰胺）、磷脂酸磷酸水解酶抑制剂（普萘洛尔）和二酰基甘油脂肪酶抑制剂（RHC 8e67）可减弱 Ang II 诱导的花生四烯酸释放。以[3H]磷脂酰乙醇生成量衡量，Ang II 诱导的 PLD 激活被 C2 神经酰胺抑制，但不被普萘洛尔或 RHC 8e67 抑制。Ang II 诱导的 PLD 激活被抑制剂甲基花生四烯酰氟磷酸酯（MAFP）和 cPLA2 的反义寡核苷酸降低。脂氧合酶抑制剂（黄芩苷）和细胞色素 P45o 4A 抑制剂（ODYA）可减弱 Ang II 诱导的 PLD 激活。20-HETE 和 12(S)-HETE 可增加 PLD 活性。ras 法尼基转移酶抑制剂（FPT III 和 BMS-191563）和 MAP 激酶激酶抑制剂（UO126）可减弱 20-HETE 和 Ang II 引起的 PLD 活性增加。PLD2 是 Ang II 在 VSMC 中激活的主要亚型。这些数据表明，Ang II 激活 cPLA2 后从花生四烯酸生成的 CYP4A 代谢产物 20-HETE 刺激 ras/MAP 激酶途径，进而激活 PLD2，并通过磷脂酸磷酸水解酶/二酰基甘油脂肪酶途径释放更多花生四烯酸用于前列腺素合成。
