Hwang Hye Mi, Lee Jeong Hyung, Min Byung Sun, Jeon Byeong Hwa, Hoe Kwang Lae, Kim Young Myeong, Ryoo Sungwoo
Departments of Biological Sciences (H.M.H., S.R.) and Biochemistry (J.H.L.), College of Natural Sciences, and Departments of Molecular and Cellular Biochemistry (Y.M.K.), School of Medicine, Kangwon National University, Chuncheon, Gangwon-do; College of Pharmacy, Catholic University, Daegu (B.S.M.); Infectious Signaling Network Research Center, Department of Physiology, School of Medicine, (B.H.J.) and Department of New Drug Discovery and Development (K.L.H.), Chungnam National University, Daejeon, South Korea.
Departments of Biological Sciences (H.M.H., S.R.) and Biochemistry (J.H.L.), College of Natural Sciences, and Departments of Molecular and Cellular Biochemistry (Y.M.K.), School of Medicine, Kangwon National University, Chuncheon, Gangwon-do; College of Pharmacy, Catholic University, Daegu (B.S.M.); Infectious Signaling Network Research Center, Department of Physiology, School of Medicine, (B.H.J.) and Department of New Drug Discovery and Development (K.L.H.), Chungnam National University, Daejeon, South Korea
J Pharmacol Exp Ther. 2015 Oct;355(1):57-65. doi: 10.1124/jpet.115.224592. Epub 2015 Aug 11.
Elevated endothelial arginase activity decreases nitric oxide (NO) production by competing with the substrate l-arginine, previously reported, and reciprocally regulating endothelial nitric oxide synthase (eNOS) activity. Thus, arginase inhibitors may help treat vascular diseases associated with endothelial dysfunction. A screening of metabolites from medicinal plants revealed that (2S)-5,2',5'-trihydroxy-7,8-dimethoxy flavanone (TDF) was a noncompetitive inhibitor of arginase. We investigated whether TDF reciprocally regulated endothelial NO production and its possible mechanism. TDF noncompetitively inhibited arginase I and II activity in a dose-dependent manner. TDF incubation decreased arginase activity and increased NO production in human umbilical vein endothelial cells and isolated mouse aortic vessels and reduced reactive oxygen species (ROS) generation in the endothelium of the latter. These TDF-mediated effects were associated with increased eNOS phosphorylation and dimerization but not with changes in protein content. Endothelium-dependent vasorelaxant responses to acetylcholine (Ach) were significantly increased in TDF-incubated aortic rings and attenuated by incubation with soluble guanylyl cyclase inhibitor. Phenylephrine-induced vasoconstrictor responses were markedly attenuated in TDF-treated vessels from wild-type mice. In atherogenic-prone ApoE(-/-) mice, TDF attenuated the high-cholesterol diet (HCD)-induced increase in arginase activity, which was accompanied by restoration of NO production and reduction of ROS generation. TDF incubation induced eNOS dimerization and phosphorylation at Ser1177. In addition, TDF improved Ach-dependent vasorelaxation responses and attenuated U46619-dependent contractile responses but did not change sodium nitroprusside-induced vasorelaxation or N-NAME-induced vasoconstriction. The findings suggest that TDF may help treat cardiovascular diseases by reducing pathophysiology derived from HCD-mediated endothelial dysfunction.
先前有报道称，内皮细胞中升高的精氨酸酶活性会通过与底物L-精氨酸竞争，从而降低一氧化氮（NO）的生成，并相互调节内皮型一氧化氮合酶（eNOS）的活性。因此，精氨酸酶抑制剂可能有助于治疗与内皮功能障碍相关的血管疾病。对药用植物代谢产物的筛选显示，（2S）-5,2',5'-三羟基-7,8-二甲氧基黄酮（TDF）是一种精氨酸酶的非竞争性抑制剂。我们研究了TDF是否会相互调节内皮NO的生成及其可能的机制。TDF以剂量依赖的方式非竞争性抑制精氨酸酶I和II的活性。在人脐静脉内皮细胞和分离的小鼠主动脉血管中，TDF孵育可降低精氨酸酶活性并增加NO生成，同时减少后者内皮中的活性氧（ROS）生成。这些TDF介导的作用与eNOS磷酸化和二聚化增加有关，但与蛋白质含量的变化无关。在TDF孵育的主动脉环中，对乙酰胆碱（Ach）的内皮依赖性血管舒张反应显著增加，并被可溶性鸟苷酸环化酶抑制剂孵育所减弱。在TDF处理的野生型小鼠血管中，去氧肾上腺素诱导的血管收缩反应明显减弱。在易患动脉粥样硬化的载脂蛋白E基因敲除（ApoE(-/-)）小鼠中，TDF减弱了高胆固醇饮食（HCD）诱导的精氨酸酶活性增加，同时伴随着NO生成的恢复和ROS生成的减少。TDF孵育可诱导eNOS在Ser1177位点的二聚化和磷酸化。此外，TDF改善了Ach依赖性血管舒张反应并减弱了U46619依赖性收缩反应，但不改变硝普钠诱导的血管舒张或N-硝基-L-精氨酸甲酯（L-NAME）诱导的血管收缩。这些发现表明，TDF可能通过减轻HCD介导的内皮功能障碍所导致的病理生理过程，从而有助于治疗心血管疾病。
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