JAK2条件性基因敲除小鼠中髙糖刺激内皮细胞凋亡与血管内皮功能障碍的研究

Endothelial apoptosis may be a major determinant of endothelial dysfunction. Endothelial dysfunction has long been realized to be a pivotal factor contributing to the pathogenesis of diabetic cardiovascular complications, but the underlying moelcular mechanisms are yet to be fully addressed,the relationship between endothelial apoptosis and dysfunction is not clear. Our preliminary studies now provided evidence supporting that ednothelial cells (ECs) show enhanced JAK/STAT signaling after high glucose stimulation and ECs apoptosis. We therefore hypothesize that hyperglycemic stimulation induce excessive production of reactive oxygen species (ROS) and oxidative stress, which then activate JAK/STAT signaling, predisposing endothelial cells to undergoing apoptosis and functional impairment. To test the above hypothesis, We will use diabetic animals to establish that altered activation of JAK/STAT signaling acts as a key factor for induction of endothelial apoptosis and functional impairment. Then, we will assess the feasibility of blockade of JAK2 signaling for prevention and treatment of diabetic endothelial dysfunction by employing endothelial specific JAK2 and APOE deficient mice. Completion of these studies will not only provide novel insight into the understanding of the mechanisms underlying diabetic endothelial dysfunction, but also have the potential for developing effective therapeutic strategies for prevention and treatment of diabetic cardiovascular complications.

内皮细胞(ECs)凋亡引起许多危险因素导致血管内皮功能障碍，血管内皮功能障碍是导致糖尿病心血管并发症的关键因素，但其病理机制至今尚不明了，在糖尿病中，内皮细胞凋亡与血管内皮功能障碍关系仍知之甚少。申请者的前期研究揭示高糖(HG)刺激JAK/STAT信号通路活化，ECs发生凋亡。故申报者提出如下假设：HG引起内皮细胞产生过量ROS诱发氧化应激，激活JAK/STAT信号通路，导致ECs凋亡，进而导致血管内皮功能障碍。为了验证这一假说，拟在原代培养内皮细胞和JAK2条件基因敲除小鼠及JAK2/APOE双基因敲除小鼠，研究HG导致的ECs凋亡及血管内皮功能障碍的关系，阐明HG所致血管内皮损伤的分子机制，研究调控JAK/STAT信号通路对预防和治疗糖尿病诱导的ECs凋亡和内皮功能损伤的可行性。该研究不仅为解析糖尿病血管内皮损伤的分子机制提供新思路，还能为开发糖尿病心血管并发症的治疗策略提供理论基础。

糖尿病心血管并发症严重危害患者健康，糖尿病患者的早期临床检查发现其血管内皮功能障碍，但其病理机制至今尚不明了。内皮细胞(ECs)凋亡引起许多危险因素，可能导致血管内皮功能障碍。本研究发现在链脲佐菌素(STZ)处理后，内皮细胞特异性JAK2条件基因敲除小鼠（Tie2-Cre/Jak2flox）较对照组（Jak2flox）小鼠血管ECs凋亡显著减少；在苯肾上腺素刺激下的血管收缩能力检测发现，Tie2-Cre/Jak2flox小鼠较Jak2flox小鼠血管收缩显著减弱；在硝普酸钠刺激的血管舒张检查中显示，Tie2-Cre/Jak2flox小鼠较JAK2flox小鼠血管舒张能力增强。体外细胞学实验证明Jak2抑制剂能增加血管ECs抗凋亡蛋白Bcl-2的表达。为了检测JAK2在血管动脉粥样硬化中的作用，本课题组繁育获得JAK2野生型/ApoE基因敲除小鼠(JAKflox/apoE-/-)和JAK2条件/ApoE双基因敲除小鼠(Tie2-Cre/JAK2flox/apoE-/-)，在STZ注射28周后，Tie2-Cre/JAK2flox/apoE-/-较JAK2flox/apoE-/-小鼠主动脉血管斑块面积显著增加，体外实验证明抑制JAK2降低内皮粘附分子ICAM的表达，从而导致斑块形成增加。本研究提出高糖刺激血管内皮损伤继而导致内皮功能障碍，为糖尿病心血管并发症的可能分子机制，Jak2可作为糖尿病心血管并发症早期治疗的靶点。

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