胞浆型肌酸激酶cDNA的克隆及其对兴奋毒性神经细胞钙超载的保护作用

Cloning of Cytosolic Creatine Kinase's c DNA and Its Protective Effects Against Excitotoxic Calcium Overload in Neural Cells

钙离子超载是介导兴奋性神经毒性和多种神经退行性病变的重要细胞机制,胞内能量耗竭是钙超载所致神经细胞死亡的重要原因。脑源胞浆型肌酸激酶(cytosolic creatine kinase,CKBB)能通过催化生成磷酸肌酸来存储能量,提高细胞的荷能状态,对钙超载引发的细胞毒性可能具有调控作用。作者克隆了小鼠CKBB的c DNA,发现过表达CKBB能有效缓解A23187刺激引起的SH-SY5Y细胞内ATP排空,降低能量"感受器"—AMP激活的蛋白激酶(AMP-activated protein kinase,AMPK)—的磷酸化程度,并显著提高细胞存活率。在谷氨酸诱导的原代小脑颗粒神经元的钙超载体系中也证明了CKBB的保护作用。此外,还发现肌酸结合CKBB的双因素保护方案比单独的CKBB干预效果更好,该结果对于肌酸和肌酸激酶的临床应用具有一定的借鉴意义。

Intracellular calcium overload is a key mediator of neural excitotoxicity, which leads to various neurodegenerative diseases. A neural cell dies from cytosolic energy depletion when subjected to calcium overload. Cytosolic creatine kinase （CKBB） can improve the cellular energy state by storing high-energy phosphate bonds in the form of phosporylated creatine; hence, it may regulate the cytotoxicity induced by calcium overload. In this study, the authors cloned the mouse cDNA of CKBB and found that the overexpression of CKBB could effectively alleviate ATP depletion in A23187-stimulated SH-SY5Y cells, and therefore, afforded protection against calcium imbalance. CKBB also reduced Thr172 phosphorylation of AMPK, which is an indicator of the cellular energy state. The protective effect of CKBB was also confirmed using the calcium overload model of primary cerebellar granule neurons that was induced using glutamate. In addition, the results of this study showed that creatine combined with CKBB provided an enhanced neuroprotective effect than CKBB alone. These results suggest the potential of CKBB and creatine to be applied in clinical use for the treatment of neurodegenerative diseases.