Molecular and Cellular Biological Study on the Actions of Intracellular Calcium Ion in Cultured Cells

神经冲动、各种神经递质和生长激素通过提高细胞内钙离子浓度发挥作用。钙离子参与多种类型的神经功能，包括神经递质的生物合成、神经递质和激素的刺激-分泌偶联、微管组装-分解周期、突触可塑性、基因表达和许多代谢反应。这些事件包括关于时间进程的短期事件和长期事件。尽管调节大脑中钙离子作用的确切分子机制各不相同，但越来越多的证据表明，钙离子的作用是通过钙离子结合蛋白来调节的。此外，许多功能最终是由蛋白激酶和蛋白磷酸酶以钙依赖的方式进行的。为了通过钙信号通路阐明中枢神经系统的功能，我们检测了神经元、神经胶质细胞原代培养和已建立的细胞系统中钙调素依赖的蛋白激酶II(CaM Kinase II)的激活动态。我们发现，CaM激酶II是通过细胞内Ca~(2+)升高来响应细胞外刺激而激活的。此外，伴随着酶的激活，内源底物的磷酸化，酶的激活和长时程增强。

Nerve impulses, various neurotransmitters, and growth hormones exert their effects through elevation of the intracellular concentration of calcium ion (Ca^<2+>). Ca^<2+> is involved in several types of neuronal functions including biosynthesis of neurotransmitters, stimulus-secretion coupling of neurotransmitters and hormones, microtubule assembly-diassembly cycle, synaptic plasticity, gene expression and many metabolic reactions. These include the short-term and long-term events with respect to time course. Although the precise molecular mechanisms mediating the actions of Ca^<2+> in the brain diverse, accumulating evidence suggests the effects of Ca^<2+> are mediated through Ca^<2+>-binding proteins. Furthermore, many of the functions are ultimately conducted by protein kinases and protein phosphatases in a Ca^<2+>-dependent manner. In an attempt to elucidate the functions in the central nervous system through calcium signaling pathways, we have been examining the dynamic state of activation of Ca^<2+>/calmodulin-dependent protein kinase II (CaM kinase II) in primary cultures of neurons and glias and established cell systems. We found that CaM kinase II is activated through elevation of intracellular Ca^<2+> in response to the extracellular stimuli. Firthermore, with concomitant activation of the enzyme, phosphorylation of endogenous substrates, activation of the enzyme and long-term potentiation were observed.