A model of TRPV4 channelopathy

描述(申请人提供)：周围神经病导致运动和感觉神经纤维轴突变性，导致肌肉无力和感觉丧失。由于对潜在的分子和细胞触发因素的不完全了解，以及缺乏可用药的治疗靶点，有效治疗方法的开发一直受到阻碍。瞬时受体电位香草样物质4(TRPV4)突变导致2C型Charcot-Marie-Tooth病的发现标志着离子通道导致遗传性感觉运动神经病的第一个例子。TRPV4在细胞表膜上表达，目前已开发出几种小分子拮抗剂。为了进一步研究TRPV4诱导神经病变的机制，我们最近建立了一种新的包含内源性小鼠TRPV4基因R269C突变的敲入小鼠模型。我们对敲击小鼠的初步研究表明，它们的周围神经生理异常。利用这个模型，我们建议1)描述TRPV4R269C基因敲入小鼠神经元功能障碍和变性的时空演变；2)验证我们的假设，即R269C突变导致神经元中TRPV4通道活动的增强，而TRPV4拮抗剂可以抑制该通道活动。这些研究将共同确定神经病变相关的TRPV4突变如何改变外周神经元中的TRPV4功能，评估TRPV4拮抗剂可能在多大程度上代表患者的潜在治疗策略，并确定可在未来的机制和治疗研究中利用的TRPV4诱导的小鼠神经变性的结果指标。

DESCRIPTION (provided by applicant): Peripheral neuropathy results in axonal degeneration of motor and sensory nerve fibers causing muscle weakness and sensory loss. Development of effective therapies has been hampered by incomplete understanding of the underlying molecular and cellular triggers and a lack of druggable therapeutic targets. The discovery that mutations of transient receptor potential vanilloid 4 (TRPV4) cause Charcot- Marie-Tooth disease type 2C marks the first example of an ion channel causing inherited sensorimotor neuropathy. TRPV4 is expressed at the cell surface membrane and several small molecule antagonists have already been developed. In order to further investigate mechanisms of TRPV4-induced neuropathy, we recently developed a novel knock-in mouse model containing the R269C mutation in the endogenous mouse TrpV4 gene. Our preliminary studies of young knock-in mice indicate abnormalities of their peripheral nerve physiology. Using this model, we propose 1) to characterize the spatial and temporal evolution of neuronal dysfunction and degeneration in TRPV4R269C knock-in mice and 2) to test our hypothesis that the R269C mutation causes of gain-of-TRPV4 channel activity in neurons that can be suppressed by TRPV4 antagonists. Together these studies will determine how neuropathy-associated TRPV4 mutations alter TRPV4 function in peripheral neurons, assess the extent to which TRPV4 antagonists may represent a potential therapeutic strategy for patients, and define outcome measures of TRPV4-induced neurodegeneration in mice that can be utilized during future mechanistic and treatment studies.