Excitability dysfunction mechanisms underlying the TDP43-dependent ALS and FTD pathogenesis

项目总结/摘要 尽管已经努力确定肌萎缩性侧索硬化症（ALS）和额颞叶萎缩性侧索硬化症的潜在机制， 脑叶变性痴呆（FTLD或FTD）的有效治疗仍然难以捉摸。运动神经元（MN）兴奋性 功能障碍仍然与ALS疾病病理学最紧密相关。许多研究都报道了 MN的兴奋性机制的改变。然而，这些数据经常相互冲突，例如过度兴奋， 低兴奋性和正常兴奋性都在ALS动物模型中观察到。如此不一致的数据 模糊了这些兴奋性变化的作用（即，神经保护性的或有害的）。大多数冲突 在ALS的突变型超氧化物歧化酶（SOD）模型中， ALS模型我们的数据（通过我们的主动资助）来自ALS的侵袭性G93 A SOD小鼠模型， 表明低兴奋性和高兴奋性疾病的变化可能同时发生在患病的 MN。在这里，我们建议检查最近的一种新的rNLS 8小鼠模型，该模型重现了病理学 在>90%的ALS患者的上下MN中观察到反式反应DNA结合蛋白43（TDP 43）包涵体 患者，导致大脑和脊髓中的神经元损失。TDP 43在大多数偶发性 ALS病例;因此，在它们之间，G93 A和rNLS 8模型代表了大多数ALS和FTD病例。 然而，迄今为止，兴奋性失调尚未在该模型中进行检查。因此，我们的目标是 表征ALS的新型rNLS 8 TDP 43小鼠模型，并将该数据与我们现有的G93 A数据进行比较 小鼠这两种模型显示了非常不同的疾病情况和进展，但最终都导致MN 失去和死亡通过比较和对比这些模型之间的兴奋性失调机制， 我们希望通过3个具体目标来解析个体改变在ALS/FTD疾病病理学中所起的作用： 目的1：在rNLS 8模型中确定MN和突触兴奋性。目前尚不清楚， 兴奋性在rNLS 8模型中改变--如在其他ALS模型中一样--以及突触兴奋性功能障碍是否 也参与其中。因此，我们将通过以下方式测量rNLS 8模型中的内在MN和突触兴奋性： 在早期、中期和晚期疾病阶段的电生理记录，然后将它们与G93 A数据进行对比。 目的2：研究离子通道和突触传入在rNLS 8小鼠脊髓神经元死亡中的作用。 我们将测量rNLS 8小鼠脊髓MN中离子通道和突触的表达水平， 和晚期疾病阶段，然后将它们与G93 A数据进行对比。 目的3：确定离子通道和突触输入在rNLS 8皮层神经元死亡中的作用 小鼠rNLS小鼠中皮质神经元的缺失重现了ALS-共病FTD的关键方面。检查是否 参与脊髓MN死亡的兴奋性机制也参与FTD痴呆，我们将测量 在rNLS 8小鼠的皮层/皮层下神经元中，在早期、中期和晚期， 疾病晚期。

Project Summary/Abstract Despite much effort to identify mechanisms underlying amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration dementia (FTLD or FTD), effective treatments remain elusive. Motoneuron (MN) excitability dysfunction remains the most tightly linked to ALS disease pathology. Much research has reported on disease alterations in the excitability mechanisms of MNs. However, these data often conflict, as hyperexcitability, hypoexcitability, and normal excitability have all been seen in animal models of ALS. Such inconsistent data obscure the role of these excitability changes (i.e., neuroprotective or detrimental). Most of these conflicting reports are seen in mutant super-oxide dismutase (SOD) models of ALS, the most commonly studied mouse model of ALS. Our data obtained (via our active grant) from the aggressive G93A SOD mouse model of ALS suggests that both hypo- and hyperexcitability disease changes might take place concurrently within diseased MNs. Here, we propose to examine a recent, novel rNLS8 mouse model that recapitulates pathologic Transactive-response DNA-binding Protein 43 (TDP43) inclusions seen in upper and lower MNs in >90% of ALS patients, leading to neuronal loss in the brain and spinal cord. TDP43 is specifically seen in most sporadic-onset ALS cases; thus, between them, the G93A and rNLS8 models represent most ALS, and also FTD, cases. However, to date, excitability dysregulation has not been examined in this model. Thus, our objective is to characterize the novel rNLS8 TDP43 mouse model of ALS and compare this data to our existing data from G93A mice. Both models demonstrate very different disease scenario and progression, yet ultimately both lead to MN loss and death. By comparing and contrasting mechanisms of excitability dysregulation between these models, we expect to parse the roles that individual alterations play in ALS/FTD disease pathology via 3 Specific Aims: Aim 1: Determine MN and synaptic excitability in the rNLS8 model. It is currently unknown whether MN excitability is altered in the rNLS8 model – as in other ALS models – and whether synaptic excitability dysfunction is also involved. Thus, we will measure intrinsic MN and synaptic excitability in the rNLS8 model via electrophysiology recordings, at early, middle, and late disease stages, then contrast them to G93A data. Aim 2: Determine the roles of ion channels and synaptic inputs in the death of spinal MNs in rNLS8 mice. We will measure expression levels of ion channels and synapses in spinal MNs of rNLS8 mice at early, middle, and late disease stages, then contrast them to G93A data. Aim 3: Determine the roles of ion channels & synaptic inputs in the death of cortical neurons in rNLS8 mice. Loss of cortical neurons in rNLS mice recapitulates key aspects of ALS-comorbid FTD. To examine if excitability mechanisms involved in the death of spinal MNs are also involved in FTD dementia, we will measure expression levels of ion channels and synapses in cortical/subcortical neurons of rNLS8 mice at early, mid, and late disease stages.