Accumulating evidence suggests that autophagy dysfunction plays a critical role in myocardial ischemia/reperfusion (I/R) injury. However, the underling mechanism of malfunctional autophagy in the cardiomyocytes subjected to I/R has not been well defined. As a result, there is no effective therapeutic option by targeting autophagy to prevent myocardial I/R injury. Here, we used both an in vitro and an in vivo I/R model to monitor autophagic flux in the cardiomyocytes, by exposing neonatal rat ventricular myocytes to hypoxia/reoxygenation and by subjecting mice to I/R, respectively. We observed that the autophagic flux in the cardiomyocytes subjected to I/R was blocked in both in vitro and in vivo models. Down-regulating a lysosomal cationic channel, TRPML1, markedly restored the blocked myocardial autophagic flux induced by I/R, demonstrating that TRPML1 directly contributes to the blocked autophagic flux in the cardiomyocytes subjected to I/R. Mechanistically, TRPML1 is activated secondary to ROS elevation following ischemia/reperfusion, which in turn induces the release of lysosomal zinc into the cytosol and ultimately blocks the autophagic flux in cardiomyocytes, presumably by disrupting the fusion between autophagosomes and lysosomes. As a result, the inhibited myocardial autophagic flux induced by TRPML1 disrupted mitochondria turnover and resulted in mass accumulation of damaged mitochondria and further ROS release, which directly led to cardiomyocyte death. More importantly, pharmacological and genetic inhibition of TRPML1 channels greatly reduced infarct size and rescued heart function in mice subjected to I/R in vivo by restoring impaired myocardial autophagy. In summary, our study demonstrates that secondary to ROS elevation, activation of TRPML1 results in autophagy inhibition in the cardiomyocytes subjected to I/R, which directly leads to cardiomyocyte death by disrupting mitochondria turnover. Therefore, targeting TRPML1 represents a novel therapeutic strategy to protect against myocardial I/R injury.

越来越多的证据表明，自噬功能障碍在心肌缺血/再灌注 (I/R) 损伤中起着关键作用。然而，经受 I/R 的心肌细胞自噬功能障碍的潜在机制尚未明确。因此，目前还没有通过靶向自噬来预防心肌 I/R 损伤的有效治疗选择。在这里，我们使用体外和体内 I/R 模型来监测心肌细胞中的自噬通量，方法是分别将新生大鼠心室肌细胞暴露于缺氧/复氧和使小鼠接受 I/R。我们观察到受 I/R 影响的心肌细胞的自噬通量在体外和体内模型中均被阻断。下调溶酶体阳离子通道 TRPML1 可显着恢复 I/R 诱导的受阻心肌自噬通量，表明 TRPML1 直接导致受 I/R 影响的心肌细胞自噬通量受阻。从机制上讲，TRPML1 在缺血/再灌注后继发于 ROS 升高而被激活，这反过来会诱导溶酶体锌释放到细胞质中并最终阻断心肌细胞中的自噬通量，这可能是通过破坏自噬体和溶酶体之间的融合。因此，TRPML1 诱导的抑制心肌自噬通量破坏了线粒体更新并导致受损线粒体的大量积累和进一步的 ROS 释放，这直接导致心肌细胞死亡。更重要的是，TRPML1 通道的药理学和遗传抑制通过恢复受损的心肌自噬大大减少了梗死面积，并在体内经受 I/R 的小鼠中挽救了心脏功能。总之，我们的研究表明继发于 ROS 升高，TRPML1 的激活导致受到 I/R 的心肌细胞的自噬抑制，这通过破坏线粒体更新直接导致心肌细胞死亡。因此，靶向 TRPML1 代表了一种防止心肌 I/R 损伤的新型治疗策略。