Meye Constanze, Schumann Joerg, Wagner Andrea, Gross Peter
Division of Nephrology, Department of Internal Medicine III, Technical University of Dresden, Dresden, Germany.
Atherosclerosis. 2007 Feb;190(2):256-63. doi: 10.1016/j.atherosclerosis.2006.03.009. Epub 2006 Apr 17.
One aspect of homocysteine (Hcy) action is the impairment of endothelial cell function due to an impairment of endothelial nitric oxide (NO) production. The activity of the endothelial isoform of NO synthase (eNOS) is regulated by its interaction with caveolin-1 (Cav-1). The aim of this study was to determine whether Hcy may alter the levels of Cav-1 and eNOS in endothelial caveolae. We isolated caveolae-enriched membrane fractions from Hcy-treated human coronary artery endothelial cells. We found that treatment with 500 microM Hcy for 6h significantly reduced the levels of Cav-1 and eNOS in caveolae compared to untreated control by 47+/-7% and by 38+/-14%, respectively. Similarly, long-term incubation (96h) of HCAEC with 100 microM Hcy led to a comparable effect. The decreased Cav-1 abundance in endothelial caveolae in response to Hcy resulted from a decrease in Cav-1 expression at the transcriptional level. The reduced levels of eNOS in caveolae were caused by a translocation of eNOS from the caveolar fractions to noncaveolar fractions. The effects of Hcy were associated with an impairment of stimulated release of NO. These results suggest that Hcy induced impairment of NO production through a modulation of Cav-1 expression associated with a loss of eNOS in caveolae.
同型半胱氨酸（Hcy）作用的一个方面是由于内皮型一氧化氮（NO）生成受损而导致内皮细胞功能受损。NO合酶（eNOS）的内皮亚型的活性通过其与小窝蛋白-1（Cav-1）的相互作用来调节。本研究的目的是确定Hcy是否可能改变内皮小窝中Cav-1和eNOS的水平。我们从经Hcy处理的人冠状动脉内皮细胞中分离出富含小窝的膜组分。我们发现，与未处理的对照相比，用500 microM Hcy处理6小时可使小窝中Cav-1和eNOS的水平分别显著降低47±7%和38±14%。同样，将人冠状动脉内皮细胞（HCAEC）与100 microM Hcy长期孵育（96小时）也产生了类似的效果。Hcy导致内皮小窝中Cav-1丰度降低是由于转录水平上Cav-1表达减少所致。小窝中eNOS水平的降低是由eNOS从小窝组分向非小窝组分的转位引起的。Hcy的这些作用与NO刺激释放受损有关。这些结果表明，Hcy通过调节与小窝中eNOS丢失相关的Cav-1表达，诱导NO生成受损。
