Guanosine triphosphate cyclohydrolase I expression and enzymatic activity are present in caveolae of endothelial cells.
Guanosine triphosphate cyclohydrolase I expression and enzymatic activity are present in caveolae of endothelial cells.
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三磷酸鸟苷环水解酶 I 表达和酶活性存在于内皮细胞的小窝中。
DOI：
10.1161/hypertensionaha.108.115709
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
Katusic,ZvonimirS
中科院分区：
文献类型：
--
作者：
Peterson,TimothyE;d'Uscio,LiviusV;Cao,Sheng;Wang,Xiao-Li;Katusic,ZvonimirS
四氢生物蝶呤是NO合成所必需的辅因子。GTP环化水解酶I（GTPCH I）是内皮细胞中四氢生物蝶呤产生的限速酶，但对该酶的亚细胞定位知之甚少。在这项研究中，我们证明，GTPCH I是本地化的小窝膜微区沿着与小窝蛋白-1和内皮NO合酶。GTPCH I活性检测分离的小窝膜从培养的内皮细胞。共聚焦和电子显微镜分析证实GTPCH I与小窝蛋白-1共定位。与体外研究一致，GTPCH I活性在来自野生型小鼠肺匀浆的分离的小窝微区中是明显的。重要的是，在小窝蛋白-1缺陷小鼠的睾丸中检测到GTPCH I活性增加2倍，表明小窝蛋白-1可能参与GTPCH I酶活性的控制。实际上，小窝蛋白-1的过表达抑制GTPCH I活性，并且四氢生物蝶呤生物合成通过小窝结构的破坏而被激活。这些研究表明，GTPCH I靶向血管内皮细胞中的小窝微结构域，四氢生物蝶呤的产生发生在内皮NO合酶附近。此外，我们的研究结果提供了新的见解GTPCH I活性的小窝外壳蛋白，小窝蛋白-1的调节。
Tetrahydrobiopterin is an essential cofactor required for the synthesis of NO. GTP cyclohydrolase I (GTPCH I) is the rate-limiting enzyme for tetrahydrobiopterin production in endothelial cells, yet little is known about the subcellular localization of this enzyme. In this study, we demonstrated that GTPCH I is localized to caveolar membrane microdomains along with caveolin-1 and endothelial NO synthase. GTPCH I activity was detected in isolated caveolar membranes from cultured endothelial cells. Confocal and electron microscopy analyses confirmed GTPCH I colocalization with caveolin-1. Consistent with in vitro studies, GTPCH I activity was evident in isolated caveolar microdomains from lung homogenates of wild-type mice. Importantly, a 2-fold increase in GTPCH I activity was detected in the aortas of caveolin-1–deficient mice, suggesting that caveolin-1 may be involved in the control of GTPCH I enzymatic activity. Indeed, overexpression of caveolin-1 inhibits GTPCH I activity, and tetrahydrobiopterin biosynthesis is activated by the disruption of caveolae structure. These studies demonstrate that GTPCH I is targeted to caveolae microdomains in vascular endothelial cells, and tetrahydrobiopterin production occurs in close proximity to endothelial NO synthase. In addition, our findings provide new insights into the regulation of GTPCH I activity by the caveolar coat protein, caveolin-1.