Lim Hyun Kyo, Lim Hyun Kyoung, Ryoo Sungwoo, Benjo Alex, Shuleri Karl, Miriel Victor, Baraban Ezra, Camara Andre, Soucy Kevin, Nyhan Daniel, Shoukas Artin, Berkowitz Dan E
Department of Anesthesiology, Johns Hopkins Hospital, The Johns Hopkins Medical Institutions, 600 N. Wolfe St., Baltimore, MD 21287, USA.
Am J Physiol Heart Circ Physiol. 2007 Dec;293(6):H3317-24. doi: 10.1152/ajpheart.00700.2007. Epub 2007 Sep 7.
Emerging evidence supports the idea that arginase, expressed in the vascular endothelial cells of humans and other species, modulates endothelial nitric oxide (NO) synthase-3 (NOS-3) activity by regulating intracellular L-arginine bioavailability. Arginase II is thought to be expressed in the mitochondria of a variety of nonendothelial cells, whereas arginase I is known to be confined to the cytosol of hepatic and other cells. The isoforms that regulate NOS-3 and their subcellular distribution, however, remain incompletely characterized. We therefore tested the hypothesis that arginase II is confined to the mitochondria and that mitochondrial arginase II reciprocally regulates vascular endothelial NO production. Western blot analysis, immunocytochemistry with MitoTracker, and immunoelectron microscopy confirmed that arginase II is confined predominantly but not exclusively to the mitochondria. Arginase activity was significantly decreased, whereas NO production was significantly increased in the aorta and isolated endothelial cells from arginase II knockout (ArgII(-/-)) mice compared with wild-type (WT) mice. The vasorelaxation response to acetylcholine (ACh) was markedly enhanced and the vasoconstrictor response to phenylephrine (PE) attenuated in ArgII(-/-) in pressurized mouse carotid arteries. Furthermore, inhibition of NOS-3 by N(G)-nitro-L-arginine methyl ester (L-NAME) impaired ACh response and restored the PE response to that observed in WT vessels. Vascular stiffness, as assessed by pulse wave velocity (PWV), was significantly decreased in ArgII(-/-) compared with WT mice. On the other hand, 14 days of oral L-NAME treatment significantly increased PWV in both WT and ArgII(-/-) mice, such that they were not significantly different from one another. These data suggest that arginase II is predominantly confined to the mitochondria and that this mitochondrial arginase II regulates NO production, vascular endothelial function, and vascular stiffness by modulating NOS-3 activity.
新出现的证据支持这样一种观点，即人类和其他物种的血管内皮细胞中表达的精氨酸酶通过调节细胞内L-精氨酸的生物利用度来调节内皮型一氧化氮（NO）合酶-3（NOS-3）的活性。精氨酸酶II被认为在多种非内皮细胞的线粒体中表达，而精氨酸酶I已知局限于肝脏和其他细胞的胞质溶胶中。然而，调节NOS-3的同工型及其亚细胞分布仍未完全明确。因此，我们检验了以下假设：精氨酸酶II局限于线粒体，并且线粒体精氨酸酶II相互调节血管内皮NO的产生。蛋白质印迹分析、用MitoTracker进行的免疫细胞化学以及免疫电子显微镜证实，精氨酸酶II主要但并非唯一局限于线粒体。与野生型（WT）小鼠相比，精氨酸酶II基因敲除（ArgII(-/-)）小鼠的主动脉和分离的内皮细胞中，精氨酸酶活性显著降低，而NO产生显著增加。在加压的小鼠颈动脉中，ArgII(-/-)小鼠对乙酰胆碱（ACh）的血管舒张反应明显增强，而对去氧肾上腺素（PE）的血管收缩反应减弱。此外，N(G)-硝基-L-精氨酸甲酯（L-NAME）对NOS-3的抑制损害了ACh反应，并使PE反应恢复到WT血管中观察到的水平。与WT小鼠相比，通过脉搏波速度（PWV）评估的血管僵硬度在ArgII(-/-)小鼠中显著降低。另一方面，口服L-NAME 14天显著增加了WT和ArgII(-/-)小鼠的PWV，使得它们彼此之间没有显著差异。这些数据表明，精氨酸酶II主要局限于线粒体，并且这种线粒体精氨酸酶II通过调节NOS-3活性来调节NO产生、血管内皮功能和血管僵硬度。
