Department of Pharmacology, School of Pharmaceutical Sciences, Central South University, Hunan, PR China.
Atherosclerosis. 2010 Mar;209(1):66-73. doi: 10.1016/j.atherosclerosis.2009.08.035. Epub 2009 Aug 28.
Elevated level of asymmetric dimethylarginine (ADMA) is an independent risk factor for endothelial dysfunction. Dimethylarginine dimethylaminohydrolase (DDAH) is the key enzyme responsible for the degradation of endogenous ADMA. The purposes of this study were to determine whether suppressed DDAH2 expression would implicate in endothelial dysfunction associated with diabetes mellitus and further to investigate whether adenovirus-mediated DDAH2 gene overexpression could improve the hyperglycemia-induced endothelial dysfunction.
Diabetic model was induced by intraperitoneal injection of streptozotocin to male Sprague-Dawley rats. Recombinant adenoviral vector encoding human DDAH2 gene driven by a cytomegalovirus promoter was constructed to overexpress hDDAH2 gene in isolated rat aortas and endothelial cells. Changes in DDHA/ADMA/nitric oxide (NO) pathway in diabetic rats and high glucose-treated endothelial cells were examined.
DDAH2 expression was distinctly suppressed, which was accompanied by inhibited DDAH activity and impaired endothelium-dependent relaxation in aortas, and elevated ADMA concentrations in serum of diabetic rats compared to control rats. Suppressions of DDAH2 expression and DDAH activity, accumulation of ADMA, and inhibition of NO synthesis were observed in high glucose-treated endothelial cells. DDAH2 overexpression not only improved endothelial dysfunction in diabetic aortas but also attenuated hyperglycemia-induced changes in DDAH/ADMA//NO pathway in endothelial cells.
These results indicate that suppression of DDAH2 expression contributes to hyperglycemia-induced endothelial dysfunction, which can be improved by DDAH2 overexpression. This study suggests that targeted modulation of DDAH2 gene in vascular endothelium may be a novel approach for the treatment of endothelial dysfunction in diabetes mellitus.
不对称二甲基精氨酸（ADMA）水平升高是内皮功能障碍的独立危险因素。二甲基精氨酸二甲氨基水解酶（DDAH）是负责内源性 ADMA 降解的关键酶。本研究旨在确定抑制 DDAH2 表达是否与糖尿病相关的内皮功能障碍有关，并进一步研究腺病毒介导的 DDAH2 基因过表达是否可以改善高血糖诱导的内皮功能障碍。
通过腹腔注射链脲佐菌素诱导雄性 Sprague-Dawley 大鼠建立糖尿病模型。构建了由巨细胞病毒启动子驱动的编码人 DDAH2 基因的重组腺病毒载体，以在分离的大鼠主动脉和内皮细胞中过表达 hDDAH2 基因。检测糖尿病大鼠和高糖处理的内皮细胞中 DDHA/ADMA/一氧化氮（NO）通路的变化。
与对照组大鼠相比，糖尿病大鼠主动脉中 DDAH2 表达明显受到抑制，伴随 DDAH 活性降低和内皮依赖性松弛功能受损，血清中 ADMA 浓度升高。高糖处理的内皮细胞中观察到 DDAH2 表达和 DDAH 活性抑制、ADMA 积累和 NO 合成抑制。DDAH2 过表达不仅改善了糖尿病大鼠主动脉内皮功能障碍，还减轻了高血糖诱导的内皮细胞中 DDAH/ADMA//NO 通路的变化。
这些结果表明，DDAH2 表达的抑制导致高血糖诱导的内皮功能障碍，DDAH2 过表达可以改善这种功能障碍。本研究表明，靶向调节血管内皮细胞中的 DDAH2 基因可能是治疗糖尿病内皮功能障碍的新方法。
