转录因子AP-2a在AMPK所介导的抗动脉粥样硬化中的作用及机制研究

Inflammation in vascular wall is crucial for atherosclerosis formation and advanced plaque rapture. We have previously obsevered that gene knockout of AMP-activated kinase (AMPK) α2 via upregulation of IkBα-mediated inflamatory signallings accelerated atherosclerotic formation in mice. However, the molecular mechanism by which AMPK regulates IkBα remain poorly understood. We also observed that activated AMPKα2 enhanced the transcriptional activity of activator protein 2α (AP-2α). Our exciting preliminary data reveal that AP-2α may bind to IkBα gene promoter. The central hypothesisof the current application is that activation of AP-2α upregulates IkBα gene transcription and mediates the anti-inflammatory and anti-atheroslcerotic effects by AMPKα2 activation. Comprehensive experimental approaches including pharmacological and genetic means will be used (1) to identity if AP-2α is the transcriptional factor of IkBα; (2) to investigate whether AP-2α-dependent upregulation of IkBα gene transcription mediates the suppressive effect of AMPKα2 activation on inflammation in cultured vascular cells, and to elucidate, and (3) to define the role AP-2α on the anti-atherosclerotic formation by AMPKa2 activation in mice. This powerful combination of in vitro and in vivo techniques and gain/loss-of-function approaches will yield important insights into how AMPKα2 activation via AP-2α prevents from atherosclerosis formation.

血管壁的慢性炎症是动脉粥样硬化（AS）斑块形成及易损破裂的关键。申请者发现敲除小鼠AMP活化的蛋白激酶a2（AMPKα2）基因通过减少IkBα的蛋白含量而加重了血管的炎症反应，但AMPKa2调节IkBα的机制不明。我们还发现AMPKα2活化能上调转录因子AP-2α的活性，预实验亦发现AP-2α蛋白能与IkBα的基因启动子结合。据此我们设想AMPKα2活化通过上调AP-2α依赖的IkBα基因转录而产生抗炎及抗AS作用。本课题拟运用多种实验方法，体外与体内研究相结合，鉴定AP-2α是IkBα的转录因子；探讨AP-2α依赖的IkBα基因转录在AMPKα2活化抗血管炎症反应中的作用；明确AP-2α是否介导了二甲双胍等AMPK激动药物的抗AS作用。通过研究AP-2α是否调节IkBα的基因表达，旨在阐明AS炎症反应及AMPKα2活化抗AS作用的分子机制。本研究将为寻找抗AS药物的新靶点提供科学依据。

长期以来公认为血管壁的慢性炎症是动脉粥样硬化斑块形成及易损破裂的关键，是临床急性冠脉综合症的罪魁祸首，但如何预防动脉粥样硬化斑块的破裂是当前学术界亟待解决的关键科学问题。我们在既往的工作中发现敲除小鼠AMP活化的蛋白激酶a2（AMPKα2）基因能减少IkBα的蛋白含量，激活NF-kB，引起血管壁的炎症反应，加速动脉粥样硬化斑块形成。通过该课题，我们进一步发激活AMPKα2后，其能从细胞浆转入细胞核，直接磷酸化转录因子AP-2α，上调IkBα的基因表达，进而抑制动脉粥样斑块内的炎症反应，不仅抑制动脉粥样斑块的形成，也促进了动脉粥样斑块的稳定性。沉默AMPK及AP-2α显著促进了高脂所喂养的Apoe-/-小鼠动脉粥样硬化斑块的形成并促进易损斑块的形成。临床常用的药物，如阿司匹林、二甲双胍、他汀等药物均能激活AMPK和AP-2α，抑制血管壁和动脉粥样硬化斑块内的炎症反应，降低急慢性心血管事件。在人动脉粥样硬化患者的冠状动脉，IkBα表达减少和氧化应激增加与动脉粥样硬化病变进展有关，而AMPK和AP-2α的磷酸化水平显著降低。我们的结果表明动脉粥样硬化患者除了正常降脂、抗血栓等治疗外，加用二甲双胍等能激活AMPK的药物有望预防心血管疾病的发生，降低心肌梗死的死亡率，改善预后，提高生活质量。