Calpain and mitochondria in ischemia/reperfusion injury
Calpain and mitochondria in ischemia/reperfusion injury
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DOI：
10.1074/jbc.m204951200
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发表时间：
2002-08-09
影响因子：
4.8
通讯作者：
Gottlieb, RA
中科院分区：
文献类型：
--
作者：
Chen, M;Won, DJ;Gottlieb, RA
缺血/再灌注（I/R）损伤和预处理的研究表明，离子稳态，特别是钙稳态，是限制组织损伤的关键。然而，离子稳态和特定的细胞死亡途径之间的关系尚未在I/R的背景下进行研究。以前我们报道过钙蛋白酶在没有可检测到的半胱天冬酶激活的情况下切割Bid（1）。在这项研究中，我们已经表明，抑制剂的钠/氢交换防止钙蛋白酶激活后LIR。钙蛋白酶抑制剂阻止Bid的裂解以及细胞死亡的下游指标，包括DNA链断裂、肌酸激酶（CK）释放和通过氯化三苯基四唑（TTC）染色测量的梗死。相反，广谱半胱天冬酶抑制剂IDN 6734在该模型中没有保护作用。为了确定这些事件下游的线粒体功能障碍是否是必需的步骤，我们利用了与HIV达特的蛋白转导结构域（TAT-BH 4）缀合的对应于Bcl-x（L）的残基4-23的肽，其已显示出保护线粒体免受Ca 2+诱导的DeltaPsi（m）损失（2）。TAT-BH 4减弱了CK释放和TTC染色的丧失，证明了线粒体和促凋亡Bcl-2家族成员在导致细胞死亡的过程中的作用。我们提出以下途径。(i)再灌注导致钠内流，随后是钙积累。(ii)这导致钙蛋白酶激活，进而导致Bid裂解。(iii)Bid靶向线粒体，引起功能障碍和促凋亡因子的释放，导致DNA片段化和细胞死亡。缺血/再灌注启动细胞死亡途径，这是独立的半胱天冬酶，但需要钙蛋白酶和线粒体功能障碍。
Studies of ischemia/reperfusion (I/R) injury and preconditioning have shown that ion homeostasis, particularly calcium homeostasis, is critical to limiting tissue damage. However, the relationship between ion homeostasis and specific cell death pathways has not been investigated in the context of I/R. Previously we reported that calpain cleaved Bid in the absence of detectable caspase activation (1). In this study, we have shown that an inhibitor of the sodium/hydrogen exchanger prevented calpain activation after LIR. Calpain inhibitors prevented cleavage of Bid as well as the downstream indices of cell death, including DNA strand breaks, creatine kinase (CK) release, and infarction measured by triphenyl tetrazolium chloride (TTC) staining. In contrast, the broad spectrum caspase inhibitor IDN6734 was not protective in this model. To ascertain whether mitochondrial dysfunction downstream of these events was a required step, we utilized a peptide corresponding to residues 4-23 of Bcl-x(L) conjugated to the protein transduction domain of HIV TAT (TAT-BH4), which has been shown to protect mitochondria against Ca2+-induced DeltaPsi(m) loss (2). TAT-BH4 attenuated CK release and loss of TTC staining, demonstrating the role of mitochondria and a pro-apoptotic Bcl-2 family member in the process leading to cell death. We propose the following pathway. (i) Reperfusion results in sodium influx followed by calcium accumulation. (ii) This leads to calpain activation, which in turn leads to Bid cleavage. (iii) Bid targets the mitochondria, causing dysfunction and release of pro-apoptotic factors, resulting in DNA fragmentation and death of the cell. Ischemia/reperfusion initiates a cell death pathway that is independent of caspases but requires calpain and mitochondrial dysfunction.