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目的探讨免疫蛋白酶体亚基β5i特异性抑制剂PR-957在心脏缺血/再灌注(I/R)损伤中的作用及机制。方法 32只雄性C57BL/6J小鼠随机分为四组:假手术组、假手术+PR-957组、缺血/再灌注组和缺血/再灌注+PR-957组。在心肌缺血/再灌注前一天皮下注射β5i特异性抑制剂PR-957(12 mg/kg)一次,然后结扎左心室左前降支30分钟再灌注24小时。小鼠处死后采用2,3,5-氯化三苯基四氮唑(TTC)染色观察心肌梗死面积;TUNEL染色检测心肌细胞凋亡情况;Western blot检测心脏组织中钙调神经磷酸酶A(Calcineurin A)蛋白水平。结果与假手术组相比,缺血/再灌注引起心肌中β5i蛋白水平明显降低;而导致梗死面积增大、细胞凋亡数量增多和钙调神经磷酸酶A蛋白水平增高;应用β5i抑制剂PR-957处理后进一步加重了缺血/再灌注引起的这些改变。结论抑制免疫蛋白酶体亚基β5i活性可加重缺血/再灌注引起的心肌损伤,其机制作用部分是通过减少钙调神经磷酸酶A被蛋白酶体降解。
Objective To investigate the role and mechanism of PR-957, a specific inhibitor of the immune proteasome subunit β5i, in cardiac ischemia / reperfusion (I / R) injury. Methods Thirty-two male C57BL / 6J mice were randomly divided into four groups: sham operation group, sham operation + PR-957 group, ischemia / reperfusion group and ischemia / reperfusion + PR-957 group. The β5i-specific inhibitor PR-957 (12 mg / kg) was injected subcutaneously one day prior to myocardial ischemia / reperfusion and the left anterior descending branch of the left ventricle was ligated for 30 min followed by 24 h reperfusion. The mice were sacrificed and the area of myocardial infarction was observed by TTC staining. TUNEL staining was used to detect the cardiomyocyte apoptosis. Western blot was used to detect the expression of calcineurin A Calcineurin A) protein level. Results Compared with the sham operation group, the level of β5i protein in myocardium was significantly decreased after ischemia / reperfusion, leading to the increase of infarct size, the increase of apoptosis and the increase of calcineurin A protein. The application of β5i inhibitor PR -957 treatment further exacerbated these changes due to ischemia / reperfusion. Conclusion Inhibition of β5i activity in the immune proteasome subunits may aggravate myocardial injury induced by ischemia / reperfusion. The mechanism of action is partly through the degradation of calcineurin A by proteasomes.