腺苷受体A2/cAMP-PKA信号通路调控自噬流保护心肌再灌注损伤机制研究

Acute myocardial infarction (AMI) is a kind of severe heart disease with high morbidity and mortality，while reperfusion therapy is a main therapy. However, the major adverse effect of reperfusion therapy is myocardial reperfusion injury, which seriously affects the prognosis of patients. Therefore, preventing myocardial reperfusion injury is an important way to improve the survival rate of patients with myocardial infarction. Autophagy flux contains the process of formation and clearance of autophagysome. Our previous studies have found that adenosine receptor A2 can down -regulate autophagy and activate autophagy flux, protecting the myocardium from injury. It was found that adenosine receptor A2 activates cAMP-PKA signaling pathway, and cAMP-PKA signaling pathway is an important signaling pathway for regulating autophagy. We hypothesize that adenosine receptor A2 activates cAMP-PKA signaling pathway, on the one hand able to regulate mTORC1, ULK2, Foxo1 affecting autophagosome formation of key molecules Atg13, LC3-II, p62, on the other hand to regulate SNARE protein family members syntaxin-17, VAMP8, Snap-29 affecting of autophagosome clearance, then reduce the accumulation of autophagosomes, ROS, myocardial cell death, and myocardial reperfusion injury. This study will provide a theoretical basis for adenosine receptor A2 agonists treatment for myocardial reperfusion injury.

急性心肌梗死病人的再灌注治疗中防止心肌再灌注损伤是提高患者存活率的重要途径。我们前期研究发现自噬流能够调控心肌再灌注损伤，缺血期主要起保护作用，再灌注期自噬却会对心肌细胞造成损害，腺苷受体A2能够下调心肌再灌注过程中的心肌细胞的自噬，但具体机制尚有待进一步研究。我们推测腺苷受体A2可激活cAMP-PKA信号通路，一方面能够调节mTORC1影响自噬体形成关键分子Atg13，另一方面调节SNARE蛋白家族成员影响自噬体清除，活化自噬流，减少心肌细胞的死亡，降低心肌再灌注损伤。为了验证这一假说，课题首先建立野生型和A2基因敲除C57BL/6小鼠心肌细胞系，研究ARA2受体通过cAMP-PKA信号通路调节自噬流进而影响心肌再灌注损伤的作用，然后采用CRISPR技术构建PKA敲除的突变体，进一步研究其在这一信号通路调控自噬流的机制，本研究将为腺苷受体A2激动剂治疗心肌再灌注损伤提供理论依据。

急性心肌梗死是致死率高、致残率高的心血管疾病之一，及时的血管再通是最重要的治疗方案。然而，心肌缺血再灌注后会导致一系列严重的并发症，影响心梗病人的预后。因此，再灌注治疗中防止心肌再灌注损伤是提高患者存活率的重要途径。我们前期研究发现再灌注期间自噬过度激活会对心肌细胞造成损害，腺苷A2受体能够下调心肌再灌注过程中的心肌细胞的自噬，但具体机制尚有待进一步研究。我们通过建立体内、体外心肌缺血再灌注损伤模型，通过给予腺苷A2A、A2B受体的激动剂和抑制剂，观察到激活腺苷A2受体对心肌组织和细胞起到保护作用，而抑制腺苷A2受体可加重再灌注损伤。再灌注期间自噬的过度增强、自噬小体清除障碍可被激活的腺苷A2受体抑制，这种作用可被PKA抑制剂H89所逆转，证明cAMP-PKA信号通路参与了腺苷A2受体对自噬的调控从而发挥心肌保护作用。我们的研究为腺苷A2受体激动剂治疗心肌再灌注损伤提供理论依据。