Cross-talk between the calpain and caspase-3 proteolytic systems in the diaphragm during prolonged mechanical ventilation.
Cross-talk between the calpain and caspase-3 proteolytic systems in the diaphragm during prolonged mechanical ventilation.
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DOI：
10.1097/ccm.0b013e318246bb5d
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发表时间：
2012-06
影响因子：
8.8
通讯作者：
Powers SK
中科院分区：
文献类型：
--
作者：
Nelson WB;Smuder AJ;Hudson MB;Talbert EE;Powers SK
由于萎缩和收缩功能障碍引起的膈肌无力是长期机械通气（MV）后的一种有据可查的反应。有证据表明，蛋白酶钙蛋白酶和半胱天冬酶-3的活化是MV诱导的神经衰弱发生所必需的。我们测试了这一假设，即在长时间的MV中，膈肌中钙蛋白酶和半胱天冬酶-3之间存在调节性串扰。为了验证这一预测，我们确定了选择性药理学抑制钙蛋白酶是否会阻止半胱天冬酶-3的激活，反之，选择性抑制半胱天冬酶-3是否会减弱钙蛋白酶的激活。动物实验。将动物随机分成对照组或三个12小时MV组之一，所述MV组用/不用选择性药理学蛋白酶抑制剂处理：1）对照; 2）MV; 3）用选择性半胱天冬酶-3抑制剂的MV;和4）用选择性钙蛋白酶抑制剂的MV。与对照组相比，MV导致I型、IIa型和IIx/IIb型纤维萎缩的膈肌中钙蛋白酶和半胱天冬酶-3活化。钙蛋白酶或半胱天冬酶-3的独立抑制防止这种MV诱导的萎缩。钙蛋白酶的药理学抑制防止MV诱导的细胞内半胱天冬酶-3的活化，并且半胱天冬酶-3的抑制防止细胞内钙蛋白酶的活化。此外，钙蛋白酶抑制还阻止了半胱天冬酶-9和半胱天冬酶-12的活化，沿着Bid裂解为tBid，所有这些都是半胱天冬酶-3活化的上游信号。最后，半胱天冬酶-3抑制防止MV诱导的内源性钙蛋白酶抑制剂，钙蛋白酶抑制素的降解。总的来说，这些结果表明MV诱导的脑萎缩依赖于钙蛋白酶和半胱天冬酶-3的激活。重要的是，这些发现提供了第一个实验证据，在膈肌中，钙蛋白酶抑制防止激活的半胱天冬酶-3，反之亦然，半胱天冬酶-3抑制防止激活的钙蛋白酶。这些研究结果支持我们的假设，即调节钙蛋白酶/caspase-3的串扰存在，从而钙蛋白酶可以促进caspase-3的激活和活性caspase-3可以增强钙蛋白酶活性在膈肌在延长MV。
Diaphragmatic weakness, due to both atrophy and contractile dysfunction, is a well-documented response following prolonged mechanical ventilation (MV). Evidence indicates that activation of the proteases calpain and caspase-3 are essential for MV-induced diaphragmatic weakness to occur. We tested the hypothesis that a regulatory cross-talk exists between calpain and caspase-3 in the diaphragm during prolonged MV. To test this prediction, we determined if selective pharmacological inhibition of calpain would prevent activation of caspase-3 and conversely, if selective inhibition of caspase-3 would abate calpain activation. Animal study. University Research Laboratory Female Sprague-Dawley rats Animals were randomly divided into a control or one of three 12 hour MV groups that were treated with/without a selective pharmacological protease inhibitor: 1) control; 2) MV; 3) MV with a selective caspase-3 inhibitor; and 4) MV with a selective calpain inhibitor. Compared to control, MV resulted in calpain and caspase-3 activation in the diaphragm accompanied by atrophy of type I, type IIa, and type IIx/IIb fibers. Independent inhibition of either calpain or caspase-3 prevented this MV-induced atrophy. Pharmacological inhibition of calpain prevented MV-induced activation of diaphragmatic caspase-3 and inhibition of caspase-3 prevented activation of diaphragmatic calpain. Further, calpain inhibition also prevented the activation of caspase-9 and caspase-12, along with the cleavage of Bid to tBid, all upstream signals for caspase-3 activation. Lastly, caspase-3 inhibition prevented the MV-induced degradation of the endogenous calpain inhibitor, calpastatin. Collectively, these results indicate that MV-induced diaphragmatic atrophy is dependent upon the activation of both calpain and caspase-3. Importantly, these findings provide the first experimental evidence in diaphragm muscle that calpain inhibition prevents the activation of caspase-3 and vice versa, caspase-3 inhibition prevents the activation of calpain. These findings support our hypothesis that a regulatory calpain/caspase-3 cross-talk exists whereby calpain can promote caspase-3 activation and active caspase-3 can enhance calpain activity in diaphragm muscle during prolonged MV.