Mechanisms Underlying Excitability Regulation of Motoneuron Types in ALS

 描述(申请人提供)：肌萎缩侧索硬化症(ALS)是一种无法治愈的致命疾病，其特征是快抽动脊髓运动神经元(F-MN)先于慢抽动脊髓运动神经元(S-MNS)选择性死亡，这种退变差异表明S-MN比F-MNS更不容易受到ALS的影响。利鲁唑是唯一一种治疗ALS的药物，只能延长3个月的生命；因此，了解S-MNS延长生命或加速F-MNS死亡的机制可以为更有效的治疗提供靶点。我们以前的工作表明，S-MN和F-MN对SK通道的内在表达是不同的。由于SK电流参与了MN兴奋性的调节，这可能解释了ALS患者S和F-MNS之间的易感性差异。理解肌萎缩侧索硬化症的MN兴奋性失调是具有挑战性的，因为正在进行的疾病和代偿性变化具有相反的正反兴奋性效应，从而维持伪正常的净兴奋性，从而掩盖了疾病的进展。由于多种变化同时发生，而且一些变化不能在实验中直接测量，实验方法需要计算机模拟的支持，这些计算机模拟足够准确地分析单个细胞变化对整体MN兴奋性的影响。因此，为了研究肌萎缩侧索硬化症S-和F-MNS易损性差异的机制，我们将基于体外动物数据开发高保真计算模型。这些模型将被用来检验不同SK通道表达水平在S-和F-MN之间的影响。虽然计算模型是有用的，但它们的预测是需要通过实验工具进行挑战和验证的理论。因此，我们将使用免疫组织化学和电生理学实验来测试转基因小鼠的模型预测。这些实验的数据将被用来在迭代周期中更新计算模型，以产生具有更准确预测的“下一代”计算模型。由此产生的预测将被用于计划更多的实验，以严格测试关于SK通道对S与F-MNS总体疾病进展的贡献的假设。

 DESCRIPTION (provided by applicant): Amyotrophic lateral sclerosis (ALS) is an incurable, fatal disease characterized by selective death of fast- twitch spinal motoneurons (F-MNs) before slow-twitch spinal motoneurons (S-MNs), a degeneration differential which suggests that S-MNs are less vulnerable to ALS than F-MNs. Riluzole, the only ALS treatment, extends life by only 3 months; thus, understanding the mechanisms that prolong life in S-MNs or hasten death in F-MNs could provide targets for more effective treatments. Our previous work has shown that S- and F-MNs differ in their intrinsic expression of SK channels. As SK current contributes to MN excitability regulation, this could potentially explain the vulnerability differential between S- ad F-MNs in ALS. Understanding MN excitability dysregulation in ALS is challenging because ongoing disease and compensatory changes have opposing pro- and anti-excitability effects that maintain a pseudo-normal net excitability which masks disease progression. Because multiple changes take place concurrently, and because some changes cannot be directly measured in experiments, experimental methods require the support of computer simulations that are accurate enough to analyze the effects of individual cellular changes on overall MN excitability. Therefore, to study mechanisms underlying the vulnerability differential between S- and F-MNs in ALS, we will develop high-fidelity computational models based on in-vitro animal data. These models will be used to examine the impact of differing SK channel expression levels between S- and F-MNs. While computational models are useful, their predictions are theories which require challenge and validation by experimental tools. Therefore, we will use immunohistochemistry and electrophysiology experiments to test model predictions in transgenic mice. The data from these experiments will be used to update the computational models, in an iterative cycle, to produce a "next generation" of computational models with even more accurate predictions. Resulting predictions will be used to plan additional experiments to rigorously test hypotheses on the contribution of SK channels to overall disease progression in S- vs. F-MNs.