Calpain mediates excitotoxic DNA fragmentation via mitochondrial pathways in adult brains - Evidence from calpastatin mutant mice
Calpain mediates excitotoxic DNA fragmentation via mitochondrial pathways in adult brains - Evidence from calpastatin mutant mice
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DOI：
10.1074/jbc.m414552200
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发表时间：
2005-04-22
影响因子：
4.8
通讯作者：
Saido, TC
中科院分区：
文献类型：
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作者：
Takano, J;Tomioka, M;Saido, TC
钙蛋白酶与兴奋毒性神经变性有关，但其作用机制，特别是在成人大脑中的作用机制仍不清楚。我们产生了缺乏或过度表达钙蛋白酶抑制蛋白的突变小鼠，钙蛋白酶抑制蛋白是唯一被鉴定或合成的钙蛋白酶特异性抑制剂。在正常条件下，钙蛋白酶抑制蛋白表达的调节在小鼠中没有引起缺陷，表明钙蛋白酶抑制蛋白仅在病理条件下作为钙蛋白酶的负调节剂起作用。红藻氨酸诱发的兴奋性毒性在海马导致蛋白水解激活的促凋亡Bcl-2亚家族成员（Bid），核转位的海马衍生的DNA片段化因子（凋亡诱导因子和核酸内切酶G），DNA片段化，并在锥体神经元核凝聚。这些凋亡反应显着增强钙蛋白酶抑制蛋白缺乏。钙蛋白酶抑制蛋白过度表达抑制了它们。未检测到半胱天冬酶-3活化的证据。我们的研究结果表明，钙蛋白酶介导的兴奋性毒性信号，通过动员促凋亡因子在半胱天冬酶的独立方式。这些突变小鼠将成为研究钙蛋白酶参与各种疾病的有用工具。
Calpain has been implicated in excitotoxic neurodegeneration, but its mechanism of action particularly in adult brains remains unclear. We generated mutant mice lacking or overexpressing calpastatin, the only solely calpain-specific inhibitor ever identified or synthesized. Modulation of calpastatin expression caused no defect in the mice under normal conditions, indicating that calpastatin functions as a negative regulator of calpain only under pathological conditions. Kainate-evoked excitotoxicity in hippocampus resulted in proteolytic activation of a proapoptotic Bcl-2 subfamily member ( Bid), nuclear translocation of mitochondria-derived DNA fragmentation factors (apoptosis-inducing factor and endonuclease G), DNA fragmentation, and nuclear condensation in pyramidal neurons. These apoptotic responses were significantly augmented by calpastatin deficiency. Consistently calpastatin overexpression suppressed them. No evidence of caspase-3 activation was detected. Our results demonstrated that calpain mediates excitotoxic signals through mobilization of proapoptotic factors in a caspase-independent manner. These mutant mice will serve as useful tools for investigating calpain involvement in various diseases.