Pathogenesis of TRPV4-related peripheral neuropathy

项目摘要/摘要 夏科-玛丽-图斯(Charcot-Marie-Tooth，CMT)病是全世界最常见的遗传性神经系统疾病，由 周围神经变性，导致进行性感觉丧失和肌肉无力。尽管 识别80多个致病基因，CMT由于对疾病的不完全理解而缺乏治疗 机制和缺乏合理的药物靶点。TRPV4(瞬时受体电位香草素)基因突变 钙渗透性非选择性离子通道，导致C型CMT(CMT2C)。TRPV4的独特之处在于它 代表了CMT中唯一的膜表达离子通道，因此是一个潜在的治疗靶点。TRPV4 已知可以调节上皮细胞的细胞骨架变化，但在神经元中还没有类似的作用 已经成立了。由于神经元细胞骨架的变化对神经元的发育和维持至关重要，因此 在钙信号的调控下，明确TRPV4在调节神经元细胞骨架中的作用具有重要意义 CMT2C的发病机制以及其他神经退行性疾病的潜在意义。我们的 在细胞、原代神经元和果蝇中的集体初步研究表明，TRPV4可以促进轴突生长 但这一功能被导致神经病变的突变所破坏。我们还使用了不偏不倚 蛋白质组学鉴定TRPV4相互作用蛋白，包括Syndapin-1和RhoA，它们在 调节神经元的生长。具体目标1将定义WT和突变体TRPV4如何影响Syndapin-1和 RhoA依赖的细胞骨架重塑途径及TRPV4离子通道的相互调节 功能和突变毒性。具体目标2将解决野生型和突变型TRPV4在调节 初级感觉神经元和运动神经元的神经元形态发生。在具体目标3中，我们将使用一只果蝇 TRPV4神经病模型及我们新近培育的TRPV4突变型敲击小鼠的体内研究 神经病突变的影响。我们还将研究RhoA和Syndapin的基因操作或 对TRPV4通道活性的药理学操作可以改变果蝇的神经元表型。这些实验 在这项提案中将定义TRPV4在神经元细胞骨架重塑和 形态发生，研究TRPV4神经病的特定致病机制，并确定 TRPV4可以在体内作为治疗靶点。综上所述，这些研究将为 TRPV4在轴突健康和疾病中的作用，并将为未来开发基于TRPV4的治疗提供信息 治疗CMT2C和其他形式的轴索性神经病的策略。

PROJECT SUMMARY/ABSTRACT Charcot-Marie-Tooth (CMT) disease is the most common inherited neurologic disease worldwide and causes peripheral nerve degeneration with resultant progressive sensory loss and muscle weakness. Despite identification of over 80 causative genes, CMT lacks treatments due to incomplete understanding of disease mechanisms and a lack of rational drug targets. Mutations in TRPV4 (transient receptor potential vanilloid), a calcium-permeable non-selective ion channel, cause CMT type 2C (CMT2C). TRPV4 is unique in that it represents the only membrane-expressed ion channel in CMT and thus a potential therapeutic target. TRPV4 is known to regulate cytoskeletal changes in epithelial cells, but a similar role in neurons has not been established. As neuronal cytoskeletal changes are critical for neuronal development and maintenance and are regulated by calcium signaling, defining the role of TRPV4 in modulating neuronal cytoskeleton has important implications for the pathogenesis of CMT2C and potentially in other neurodegenerative conditions. Our collective preliminary work in cells, primary neurons, and flies suggests that TRPV4 can promote neurite outgrowth, but that this function is disrupted by neuropathy-causing mutations. We have also used unbiased proteomics to identify TRPV4 interacting proteins, including syndapin-1 and RhoA, which have known roles in regulating neuronal outgrowth. Specific Aim 1 will define how WT and mutant TRPV4 influence syndapin-1 and RhoA-dependent cytoskeletal remodeling pathways and examine reciprocal regulation of TRPV4 ion channel function and mutant toxicity. Specific Aim 2 will address the role of wild type and mutant TRPV4 in regulating neuronal morphogenesis in primary sensory and motor neurons. In Specific Aim 3, we will use a Drosophila model of TRPV4 neuropathy and our recently generated TRPV4 mutant knockin mice to interrogate the in vivo effects of neuropathy mutations. We will also examine whether genetic manipulation of RhoA and syndapin or pharmacologic manipulation of TRPV4 channel activity can alter neuronal phenotypes in flies. The experiments in this proposal will define the normal function of TRPV4 in neuronal cytoskeletal remodeling and morphogenesis, investigate specific pathogenetic mechanisms in TRPV4 neuropathy, and determine whether TRPV4 can be therapeutically targeted in vivo. Together, these studies will provide important insights into the role of TRPV4 in axonal health and disease and will inform future efforts to develop TRPV4-based therapeutic strategies for CMT2C and perhaps other forms of axonal neuropathy.