Titin is a target of matrix metalloproteinase-2: implications in myocardial ischemia/reperfusion injury.
Titin is a target of matrix metalloproteinase-2: implications in myocardial ischemia/reperfusion injury.
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DOI：
10.1161/circulationaha.109.930222
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发表时间：
2010-11-16
期刊：
影响因子：
37.8
通讯作者：
Schulz R
中科院分区：
文献类型：
--
作者：
Ali MA;Cho WJ;Hudson B;Kassiri Z;Granzier H;Schulz R
肌动蛋白是最大的哺乳动物(∼3000-4000 kDa)和肌丝蛋白，它在心肌肌节中起着分子弹簧的作用，决定着心脏的收缩和舒缩功能。肌动蛋白在缺血心脏中的丢失已有报道，但肌动蛋白降解的机制尚不清楚。基质金属蛋白酶-2(MMP2)定位于心肌肌节，在缺血/再灌注损伤中被激活后，蛋白分解特定的肌丝蛋白。在这里，我们确定肌动蛋白是否是基质金属蛋白酶-2的细胞内底物，以及它在缺血/再灌注期间的降解是否导致心脏收缩功能障碍。免疫组织化学和共聚焦显微镜显示，在大鼠和人心脏中，基质金属蛋白酶-2和肌动蛋白在肌动蛋白的Z盘区有离散的共定位，并且主要定位于靠近心肌肌节Z盘区的肌动蛋白。当与基质金属蛋白酶-2孵育时，提纯的肌动蛋白或肌动蛋白均被浓度依赖的方式分解，而这种作用可被基质金属蛋白酶抑制剂所阻止。大鼠心肌缺血再灌注损伤后，凝胶电泳法显示心肌提取液中有肌动蛋白的裂解，组织切片中肌动蛋白免疫染色减弱。用ONO-4817抑制基质金属蛋白酶活性可阻止缺血/再灌流引起的肌动蛋白降解，并促进心肌收缩功能的恢复。与野生型对照相比，体内经历了缺血/再灌流的基质金属蛋白酶-2基因敲除小鼠的心脏肌动蛋白降解也减少了。基质金属蛋白酶-2定位于心肌肌节Z盘区的肌动蛋白，在心肌缺血/再灌注损伤中参与肌动蛋白的降解。
Titin is the largest mammalian (∼3000-4000 kDa) and myofilament protein which acts as a molecular spring in the cardiac sarcomere and determines systolic and diastolic function. Loss of titin in ischemic hearts has been reported, but the mechanism of titin degradation is not well understood. Matrix metalloproteinase-2 (MMP-2) is localized to the cardiac sarcomere and upon activation in ischemia/reperfusion injury proteolyzes specific myofilament proteins. Here we determine whether titin is an intracellular substrate for MMP-2 and if its degradation during ischemia/reperfusion contributes to cardiac contractile dysfunction. Immunohistochemistry and confocal microscopy in rat and human hearts showed discrete co-localization between MMP-2 and titin in the Z-disc region of titin and that MMP-2 is mainly localized to titin near the Z-disc of the cardiac sarcomere. Both purified titin or titin in skinned cardiomyocytes were proteolyzed when incubated with MMP-2 in a concentration-dependent manner and this was prevented by MMP inhibitors. Isolated rat hearts subjected to ischemia/reperfusion injury showed cleavage of titin in ventricular extracts by gel electrophoresis which was confirmed by reduced titin immunostaining in tissue sections. Inhibition of MMP activity with ONO-4817 prevented ischemia/reperfusion-induced titin degradation and improved the recovery of myocardial contractile function. Titin degradation was also reduced in hearts from MMP-2 knockout mice subjected to ischemia/reperfusion in vivo, compared to wild type controls. MMP-2 localizes to titin at the Z-disc region of the cardiac sarcomere and contributes to titin degradation in myocardial ischemia/reperfusion injury.