Department of Neuroscience, University of Rome Tor Vergata, Via Montpellier, 1, 00133 Rome, Italy.
Exp Neurol. 2013 Sep;247:349-58. doi: 10.1016/j.expneurol.2012.11.002. Epub 2012 Nov 8.
Voltage-gated Ca(2+) channels (VGCCs) mediate calcium entry into neuronal cells in response to membrane depolarisation and play an essential role in a variety of physiological processes. In Amyotrophic Lateral Sclerosis (ALS), a fatal neurodegenerative disease caused by motor neuron degeneration in the brain and spinal cord, intracellular calcium dysregulation has been shown, while no studies have been carried out on VGCCs. Here we show that the subtype N-type Ca(2+) channels are over expressed in G93A cultured cortical neurons and in motor cortex of G93A mice compared to Controls. In fact, by western blotting, immunocytochemical and electrophysiological experiments, we observe higher membrane expression of N-type Ca(2+) channels in G93A neurons compared to Controls. G93A cortical neurons filled with calcium-sensitive dye Fura-2, show a net calcium entry during membrane depolarization that is significantly higher compared to Control. Analysis of neuronal vitality following the exposure of neurons to a high K(+) concentration (25 mM, 5h), shows a significant reduction of G93A cellular survival compared to Controls. N-type channels are involved in the G93A higher mortality because ω-conotoxin GVIA (1 μM), which selectively blocks these channels, is able to abolish the higher G93A mortality when added to the external medium. These data provide robust evidence for an excess of N-type Ca(2+) expression in G93A cortical neurons which induces a higher mortality following membrane depolarization. These results may be central to the understanding of pathogenic pathways in ALS and provide novel molecular targets for the design of rational therapies for the ALS disorder.
电压门控钙通道(VGCCs)介导钙离子内流进入神经元细胞,响应膜去极化,并在各种生理过程中发挥重要作用。在肌萎缩侧索硬化症(ALS)中,一种由大脑和脊髓运动神经元变性引起的致命神经退行性疾病,已经显示出细胞内钙调节异常,而尚未对 VGCCs 进行研究。在这里,我们发现 N 型钙通道亚型在 G93A 培养的皮质神经元和 G93A 小鼠的运动皮层中过度表达,与对照组相比。事实上,通过 Western blot、免疫细胞化学和电生理实验,我们观察到 G93A 神经元中 N 型钙通道的膜表达明显高于对照组。用钙敏染料 Fura-2 填充的 G93A 皮质神经元在膜去极化期间显示出净钙内流,与对照组相比显著增加。用高钾浓度(25 mM,5 小时)暴露神经元后分析神经元活力,与对照组相比,G93A 细胞存活率显著降低。N 型通道参与 G93A 更高的死亡率,因为 ω-芋螺毒素 GVIA(1 μM),选择性阻断这些通道,当添加到外液中时,能够消除 G93A 更高的死亡率。这些数据为 G93A 皮质神经元中 N 型钙表达增加导致膜去极化后死亡率增加提供了有力证据。这些结果可能是理解 ALS 发病机制的核心,并为 ALS 疾病的合理治疗设计提供新的分子靶点。
Front Cell Neurosci. 2016-9-20
J Biol Phys. 2016-6