Mattson M P, Engle M G, Rychlik B
Sanders-Brown Research Center on Aging, University of Kentucky Medical Center, Lexington 40536-0230.
Mol Chem Neuropathol. 1991 Oct;15(2):117-42. doi: 10.1007/BF03159951.
Considerable evidence suggests that altered neuronal calcium homeostasis plays a role in the neuronal degeneration that occurs in an array of neurological disorders. A reduction in microtubules, the accumulation of 8-15 nm straight filaments, and altered antigenicity toward antibodies to the microtubule-associated protein tau and ubiquitin, as well as granulovacuolar degeneration, are observed in many human neurodegenerative disorders. Progress toward understanding how and why human neurons degenerate has been hindered by the inability to examine living human neurons under controlled conditions. We used cultured human fetal cerebral cortical neurons to examine ultrastructural and antigenic changes resulting from elevations in intracellular calcium levels. Elevation of intracellular calcium by exposure to a calcium ionophore or a reduced level of extracellular Na+ for periods of hours to days caused a loss of microtubules, an increase in 8-15 nm straight filaments, and increased immunostaining with Alz-50 and 5E2 (tau antibodies) and ubiquitin antibodies. Granulovacuolar degeneration was also observed. Antigenic changes in tau were sensitive to phosphatases, and the electrophoretic mobility of tau was altered in cells exposed to calcium ionophore, indicating that tau was excessively phosphorylated as the result of elevated intracellular calcium levels. Colchicine also caused an accumulation of straight filaments and altered tau immunoreactivity, suggesting that a disruption of microtubules secondary to altered calcium homeostasis may be a key event leading to altered tau disposition and neuronal degeneration. These data demonstrate that aberrant rises in intraneuronal calcium levels can result in changes in the neuronal cytoskeleton similar to those seen in neurodegenerative disorders, and suggest that this experimental system will be useful in furthering our understanding of the cellular and molecular mechanisms of human neurological disorders.
大量证据表明，神经元钙稳态的改变在一系列神经疾病中发生的神经元变性中起作用。在许多人类神经退行性疾病中观察到微管减少、8 - 15纳米直丝的积累、对微管相关蛋白tau和泛素抗体的抗原性改变以及颗粒空泡变性。由于无法在受控条件下检查活的人类神经元，阻碍了我们对人类神经元如何以及为何发生变性的理解。我们使用培养的人类胎儿大脑皮质神经元来检查细胞内钙水平升高导致的超微结构和抗原变化。通过暴露于钙离子载体或降低细胞外钠离子水平数小时至数天来升高细胞内钙，导致微管丢失、8 - 15纳米直丝增加，以及用Alz - 50和5E2（tau抗体）和泛素抗体的免疫染色增加。还观察到颗粒空泡变性。tau的抗原变化对磷酸酶敏感，并且在暴露于钙离子载体的细胞中tau的电泳迁移率发生改变，表明由于细胞内钙水平升高tau被过度磷酸化。秋水仙碱也导致直丝积累并改变tau免疫反应性，表明钙稳态改变继发的微管破坏可能是导致tau分布改变和神经元变性的关键事件。这些数据表明，神经元内钙水平的异常升高可导致类似于神经退行性疾病中所见的神经元细胞骨架变化，并表明该实验系统将有助于进一步了解人类神经疾病的细胞和分子机制。
