Junctophilin-2 is a target of matrix metalloproteinase-2 in myocardial ischemia-reperfusion injury
Junctophilin-2 is a target of matrix metalloproteinase-2 in myocardial ischemia-reperfusion injury
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DOI：
10.1007/s00395-019-0749-7
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发表时间：
2019-11-01
影响因子：
9.5
通讯作者：
Schulz, Richard
中科院分区：
文献类型：
--
作者：
Chan, Brandon Y. H.;Roczkowsky, Andrej;Schulz, Richard
Junctophlin-2是一种结构膜蛋白，它将T管连接到肌浆网，以允许在心肌细胞中协调钙诱导的钙释放。心肌缺血再灌注损伤的兴奋收缩偶联缺陷与连接素-2蛋白降解有关。然而，目前尚不清楚预防连接素-2蛋白降解是否能促进IR损伤后心脏收缩功能障碍的恢复。基质金属蛋白酶-2(MMP2)是一种锌和钙依赖的蛋白酶，在心肌IR损伤中被氧化应激激活并裂解细胞内和细胞外底物。为了确定连接蛋白-2是否是基质金属蛋白酶-2的靶点，分离的大鼠心脏在有氧工作模式下进行有氧灌流，或用选择性的基质金属蛋白酶抑制剂ARP-100进行IR损伤。IR损伤损害了心脏收缩功能的恢复，其机制与连接素-2降解增加和心脏二联体受损有关。在IR心脏中，ARP-100可促进心脏收缩功能的恢复，减弱连接蛋白-2的蛋白分解，并防止超微结构对二聚体的损伤。免疫沉淀法和免疫组织化学方法检测到基质金属蛋白酶-2和连接素-2在有氧和IR心脏中的共同定位。原位酶谱显示，在有氧心脏中，基质金属蛋白酶活性定位于Z盘和肌节，而在IR心脏中，基质金属蛋白酶活性聚集在JPH-2纹状染色受损的部位。体外蛋白分解分析表明Junctophlin-2对MMP2的蛋白水解性很敏感，并且在计算机分析中预测在Junctophlin-2的膜占据和识别连接重复序列之间以及在Junctophlin-2的分歧区内有多个MMP2裂解位点。连接蛋白-2被基质金属蛋白酶-2降解是心肌缺血再灌注损伤的早期后果，这可能引发一系列后遗症，导致收缩功能受损。
Junctophilin-2 is a structural membrane protein that tethers T-tubules to the sarcoplasmic reticulum to allow for coordinated calcium-induced calcium release in cardiomyocytes. Defective excitation-contraction coupling in myocardial ischemia-reperfusion (IR) injury is associated with junctophilin-2 proteolysis. However, it remains unclear whether preventing junctophilin-2 proteolysis improves the recovery of cardiac contractile dysfunction in IR injury. Matrix metalloproteinase-2 (MMP-2) is a zinc and calcium-dependent protease that is activated by oxidative stress in myocardial IR injury and cleaves both intracellular and extracellular substrates. To determine whether junctophilin-2 is targeted by MMP-2, isolated rat hearts were perfused in working mode aerobically or subjected to IR injury with the selective MMP inhibitor ARP-100. IR injury impaired the recovery of cardiac contractile function which was associated with increased degradation of junctophilin-2 and damaged cardiac dyads. In IR hearts, ARP-100 improved the recovery of cardiac contractile function, attenuated junctophilin-2 proteolysis, and prevented ultrastructural damage to the dyad. MMP-2 was co-localized with junctophilin-2 in aerobic and IR hearts by immunoprecipitation and immunohistochemistry. In situ zymography showed that MMP activity was localized to the Z-disc and sarcomere in aerobic hearts and accumulated at sites where the striated JPH-2 staining was disrupted in IR hearts. In vitro proteolysis assays determined that junctophilin-2 is susceptible to proteolysis by MMP-2 and in silico analysis predicted multiple MMP-2 cleavage sites between the membrane occupation and recognition nexus repeats and within the divergent region of junctophilin-2. Degradation of junctophilin-2 by MMP-2 is an early consequence of myocardial IR injury which may initiate a cascade of sequelae leading to impaired contractile function.