Suzuki Hiroyuki, Eguchi Kunie, Ohtsu Haruhiko, Higuchi Sadaharu, Dhobale Sudhir, Frank Gerald D, Motley Evangeline D, Eguchi Satoru
Cardiovascular Research Center and Department of Physiology, Temple University School of Medicine, 3420 North Broad Street, Philadelphia, Pennsylvania 19140, USA.
Endocrinology. 2006 Dec;147(12):5914-20. doi: 10.1210/en.2006-0834. Epub 2006 Sep 15.
Enhanced angiotensin II (AngII) action has been implicated in endothelial dysfunction that is characterized as decreased nitric oxide availability. Although endothelial cells have been reported to express AngII type 1 (AT1) receptors, the exact role of AT1 in regulating endothelial NO synthase (eNOS) activity remains unclear. We investigated the possible regulation of eNOS through AT1 in bovine aortic endothelial cells (BAECs) and its functional significance in rat aortic vascular smooth muscle cells (VSMCs). In BAECs infected with adenovirus encoding AT1 and in VSMCs infected with adenovirus encoding eNOS, AngII rapidly stimulated phosphorylation of eNOS at Ser1179. This was accompanied with increased cGMP production. These effects were blocked by an AT1 antagonist. The cGMP production was abolished by a NOS inhibitor as well. To explore the importance of eNOS phosphorylation, VSMCs were also infected with adenovirus encoding S1179A-eNOS. AngII did not stimulate cGMP production in VSMCs expressing S1179A. However, S1179A was able to enhance basal NO production as confirmed with cGMP production and enhanced vasodilator-stimulated phosphoprotein phosphorylation. Interestingly, S1179A prevented the hypertrophic response similar to wild type in VSMCs. From these data, we conclude that the AngII/AT1 system positively couples to eNOS via Ser1179 phosphorylation in ECs and VSMCs if eNOS and AT1 coexist. However, basal level NO production may be sufficient for prevention of AngII-induced hypertrophy by eNOS expression. These data demonstrate a novel molecular mechanism of eNOS regulation and function and thus provide useful information for eNOS gene therapy under endothelial dysfunction.
增强的血管紧张素II（AngII）作用与以一氧化氮可用性降低为特征的内皮功能障碍有关。尽管有报道称内皮细胞表达血管紧张素II 1型（AT1）受体，但AT1在调节内皮型一氧化氮合酶（eNOS）活性中的确切作用仍不清楚。我们研究了在牛主动脉内皮细胞（BAECs）中通过AT1对eNOS的可能调节及其在大鼠主动脉血管平滑肌细胞（VSMCs）中的功能意义。在感染了编码AT1的腺病毒的BAECs和感染了编码eNOS的腺病毒的VSMCs中，AngII迅速刺激eNOS在Ser1179处的磷酸化。这伴随着cGMP生成的增加。这些作用被AT1拮抗剂阻断。cGMP生成也被一氧化氮合酶抑制剂消除。为了探究eNOS磷酸化的重要性，VSMCs也感染了编码S1179A-eNOS的腺病毒。AngII在表达S1179A的VSMCs中不刺激cGMP生成。然而，如cGMP生成和增强的血管舒张刺激磷蛋白磷酸化所证实的，S1179A能够增强基础一氧化氮生成。有趣的是S1179A在VSMCs中预防了类似于野生型的肥大反应。从这些数据中，我们得出结论，如果eNOS和AT1共存，AngII/AT1系统通过ECs和VSMCs中Ser1179的磷酸化与eNOS正向偶联。然而，基础水平的一氧化氮生成可能足以通过eNOS表达预防AngII诱导的肥大。这些数据证明了eNOS调节和功能的一种新分子机制，从而为内皮功能障碍下的eNOS基因治疗提供了有用信息。
