Lipidomics, Lipid Signaling, and Vasculotoxicity Laboratory, Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Internal Medicine, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University College of Medicine, 473 W. 12th Avenue, Columbus, OH, 43210, USA.
Cell Biochem Biophys. 2013 Nov;67(2):317-29. doi: 10.1007/s12013-011-9304-3.
Mercury, especially methylmercury (MeHg), is implicated in the etiology of cardiovascular diseases. Earlier, we have reported that MeHg induces phospholipase D (PLD) activation through oxidative stress and thiol-redox alteration. Hence, we investigated the mechanism of the MeHg-induced PLD activation through the upstream regulation by phospholipase A2 (PLA2) and lipid oxygenases such as cyclooxygenase (COX) and lipoxygenase (LOX) in the bovine pulmonary artery endothelial cells (BPAECs). Our results showed that MeHg significantly activated both PLA2 (release of [(3)H]arachidonic acid, AA) and PLD (formation of [(32)P]phosphatidylbutanol) in BPAECs in dose- (0-10 μM) and time-dependent (0-60 min) fashion. The cPLA2-specific inhibitor, arachidonyl trifluoromethyl ketone (AACOCF3), significantly attenuated the MeHg-induced [(3)H]AA release in ECs. MeHg-induced PLD activation was also inhibited by AACOCF3 and the COX- and LOX-specific inhibitors. MeHg also induced the formation of COX- and LOX-catalyzed eicosanoids in ECs. MeHg-induced cytotoxicity (based on lactate dehydrogenase release) was protected by PLA2-, COX-, and LOX-specific inhibitors and 1-butanol, the PLD-generated PA quencher. For the first time, our studies showed that MeHg activated PLD in vascular ECs through the upstream action of cPLA2 and the COX- and LOX-generated eicosanoids. These results offered insights into the mechanism(s) of the MeHg-mediated vascular endothelial cell lipid signaling as an underlying cause of mercury-induced cardiovascular diseases.
汞，特别是甲基汞（MeHg），被认为与心血管疾病的病因有关。我们之前的研究报告表明，MeHg 通过氧化应激和巯基氧化还原改变诱导磷脂酶 D（PLD）的激活。因此，我们研究了在牛肺动脉内皮细胞（BPAEC）中，通过磷脂酶 A2（PLA2）和脂质氧化酶（如环氧化酶（COX）和脂氧合酶（LOX）的上游调节，MeHg 诱导 PLD 激活的机制。结果表明，MeHg 以剂量（0-10 μM）和时间（0-60 分钟）依赖性方式显著激活了 BPAEC 中的 PLA2（[3H]花生四烯酸，AA 的释放）和 PLD（[32P]磷脂酰丁醇的形成）。cPLA2 特异性抑制剂，花生四烯酸三氟甲基酮（AACOCF3）显著减弱了 MeHg 诱导的 ECs 中[3H]AA 的释放。MeHg 诱导的 PLD 激活也被 AACOCF3 和 COX 和 LOX 特异性抑制剂抑制。MeHg 还诱导了 ECs 中 COX 和 LOX 催化的类二十烷酸的形成。PLA2、COX 和 LOX 特异性抑制剂以及 PLD 生成的 PA 猝灭剂 1-丁醇保护 MeHg 诱导的细胞毒性（基于乳酸脱氢酶释放）。我们的研究首次表明，MeHg 通过 cPLA2 的上游作用和 COX 和 LOX 生成的类二十烷酸激活血管内皮细胞中的 PLD。这些结果提供了对 MeHg 介导的血管内皮细胞脂质信号机制的深入了解，作为汞诱导心血管疾病的潜在原因。
