电针通过SIRT1/HIF-1通路促进缺血脑组织VEGF表达及血管新生的机制研究

Acupuncture is a effective approach promoting the recovery of neural dysfunction in patients with cerebral infarction, but the underlying mechanisms are unclear. Our previous studies found that electroacupuncture stimulated angiogenesis and the expression of angiogenic factors such as VEGF in ischemic cerebral tissue. Recently, we found that electroacupuncture upregulated the level of SIRT1, and treatment with the SIRT1 inhibitor blocked the stimulatory effects of electroacupuncture on VEGF expression. SIRT1 catalyzes the deacetylation of HIF-1α and modulates the activity of HIF-1, which is the key transcription factor regulating the expression of VEGF. Therefore, we speculate that electroacupuncture might modulate the acetylation of HIF-1α, enhance the activity of HIF-1 and upregulate VEGF expression via SIRT1, which might be a novel mechanism underlying the beneficial effects of electroacupuncture on angiogenesis. To prove our hypothesis, we plan to confirm whether electroacupuncture regulates the activity of HIF-1 and promotes the expression of VEGF via SIRT1 at the first step. In the second step, we plan to reveal the pivotal roles of HIF-1 in the beneficial effects of electroacupuncture on angiogenesis. And finally, we plan to obtain the molecular evidence in endothelial cells cultured in low glucose medium under hypoxia circumstance via overexpression or knockdown of SIRT1 and HIF-1α. The aims of this project include investigating the novel mechanism underlying the promotive effects of electroacupuncture on angiogenesis and providing new experimental data to explain the mechanisms of acupuncture.

针刺对脑梗死后神经功能恢复有显著疗效，但机制尚不明确。我们前期发现电针可促进脑缺血后的血管新生及VEGF等促血管新生因子的表达，近期又发现电针可上调SIRT1水平、SIRT1抑制剂可阻断电针对VEGF表达的促进效应。由于SIRT1可催化HIF-1α去乙酰化并影响HIF-1的活性、而HIF-1是调控VEGF表达的关键转录因子，我们推测电针通过SIRT1调节HIF-1α的乙酰化、增强HIF-1活性并上调VEGF表达，这可能是电针促血管新生的新机制。为证实该假说，本项目拟在MCAO大鼠模型中，首先证实电针通过SIRT1调节HIF-1活性并促进VEGF表达；随后证实HIF-1在电针促血管新生中发挥重要作用；最后在缺氧低糖培养的内皮细胞中，采用过表达或干扰SIRT1、HIF-1α等手段进一步获取相关分子生物学依据。本项目旨在揭示电针促进缺血脑组织血管新生的新机制，为解释针刺疗法分子机理提供新的资料。

SIRT1是细胞的关键代谢感受器。针刺对脑缺血后神经功能恢复有显著促进作用。由于针刺对代谢的调节效应也已被长期临床实践所证实，我们从代谢感受器SIRT1探讨了针刺促进脑缺血后神经功能恢复的分子机制，发现电针刺激部分恢复了缺血引起的脑组织内SIRT1表达及活性的下调。采用SIRT1激活剂处理可有效减轻神经功能障碍，减轻缺血再灌注诱导的氧化应激，抑制缺血脑组织中的炎症反应，调节促凋亡因子Bax与抗凋亡因子Bcl-2的平衡，说明SIRT1下调在脑缺血再灌注损伤的发生发展中发挥了重要作用。SIRT1激活剂处理也可上调VEGF表达、提升HIF-1α蛋白水平；细胞水平的实验也发现SIRT1激活剂通过SIRT1-HIF-1α通路发挥上调VEGF表达、促进血管内皮细胞增殖的生物学效应。采用工具药抑制SIRT1的活性后，电针刺激诱导的HIF-1α的蛋白含量上调、VEGF的mRNA水平提升、神经功能改善等效应显著受抑，电针刺激可能通过上调SIRT1、HIF-1α提升促进VEGF的表达。因而，电针刺激可部分恢复缺血再灌注诱导的SIRT1下调，这是电针发挥促血管新生、促神经功能恢复的重要途径。