Voltage-gated calcium channels are abnormal in cultured spinal motoneurons in the G93A-SOD1 transgenic mouse model of ALS.
Voltage-gated calcium channels are abnormal in cultured spinal motoneurons in the G93A-SOD1 transgenic mouse model of ALS.
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DOI：
10.1016/j.nbd.2016.04.009
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发表时间：
2016-09
影响因子：
6.1
通讯作者：
Martin LJ
中科院分区：
文献类型：
--
作者：
Chang Q;Martin LJ
肌萎缩侧索硬化症（amyotrophiclateralsclerosis，ALS）是一种以运动神经元进行性缺失为特征的神经退行性疾病。过度兴奋和兴奋毒性与ALS的早期发病机制有关。针对兴奋性毒性运动神经元死亡和细胞内Ca 2+超载的研究主要集中在通过AMPA谷氨酸受体的Ca 2+内流。然而，运动神经元通过电压门控离子通道的内在兴奋性也可能在神经退行性变中起作用。在这项研究中，我们研究了培养的脊髓运动神经元中电压门控性钙通道的功能和定位，这些运动神经元来自表达Gly 93 →Ala取代的人超氧化物歧化酶-1突变体（G93 A-SOD 1）的小鼠。使用全细胞膜片钳记录，我们发现，高电压激活（HVA）的Ca 2+电流增加G93 A-SOD 1运动神经元，但低电压激活的Ca 2+电流不受影响。G93 A-SOD 1运动神经元也具有改变的由L型Ca 2+通道介导的持续性Ca 2+电流。定量单细胞RT-PCR显示G93 A-SOD 1运动神经元Ca 1a、Ca 1b、Ca 1c和Ca 1 e亚基mRNA表达增加，提示HVA钙电流增加可能与运动神经元Ca 2+通道mRNA表达上调有关。用免疫细胞化学和共聚焦显微镜观察运动神经元Ca 1B N型和Ca 1D L型钙通道的分布。G93 A-SOD 1可使索马和树突质膜上的Ca ~（1+）B通道增加。G93 A-SOD 1运动神经元索马胞体质膜上的Ca ~（1+）D通道相似，树突质膜上的Ca ~（1+）D通道较低。我们的研究表明，电压门控性钙通道在ALS小鼠运动神经元中具有异常的功能和定位。HVA Ca ~（2+）电流和PCCa电流的增加可能参与ALS的早期发病。
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive loss of motoneurons. Hyperexcitability and excitotoxicity have been implicated in the early pathogenesis of ALS. Studies addressing excitotoxic motoneuron death and intracellular Ca2+ overload have mostly focused on Ca2+ influx through AMPA glutamate receptors. However, intrinsic excitability of motoneurons through voltage-gated ion channels may also have a role in the neurodegeneration. In this study we examined the function and localization of voltage-gated Ca2+ channels in cultured spinal cord motoneurons from mice expressing a mutant form of human superoxide dismutase-1 with a Gly93→Ala substitution (G93A-SOD1). Using whole-cell patch-clamp recordings, we showed that high voltage activated (HVA) Ca2+ currents are increased in G93A-SOD1 motoneurons, but low voltage activated Ca2+ currents are not affected. G93A-SOD1 motoneurons also have altered persistent Ca2+ current mediated by L-type Ca2+ channels. Quantitative single-cell RT-PCR revealed higher levels of Ca1a, Ca1b, Ca1c, and Ca1e subunit mRNA expression in G93A-SOD1 motoneurons, indicating that the increase of HVA Ca2+ currents may result from upregulation of Ca2+ channel mRNA expression in motoneurons. The localizations of the Ca1B N-type and Ca1D L-type Ca2+ channels in motoneurons were examined by immunocytochemistry and confocal microscopy. G93A-SOD1 motoneurons had increased Ca1B channels on the plasma membrane of soma and dendrites. Ca1D channels are similar on the plasma membrane of soma and lower on the plasma membrane of dendrites of G93A-SOD1 motoneurons. Our study demonstrates that voltage-gated Ca2+ channels have aberrant functions and localizations in ALS mouse motoneurons. The increased HVA Ca2+ currents and PCCa current could contribute to early pathogenesis of ALS.