Genome-Wide Analysis of Ion Channels Required For Mechanosensation

描述（由申请人提供）：大量证据表明，离子通道在机械转导系统中充当力传感器。在果蝇中，无机械感受器电位-C（Nomp-C）通道已被认为是检测刚毛偏转的神经元中的力转导通道。In C.在elegans中，Deg/ENaC家族的机械转导通道已被明确地鉴定为触觉神经元中的力传感器。Mec 10/Mec 4通道是也涉及细胞外基质蛋白的转导复合物的中心组分。在细菌中，一种更简单的机械转导形式涉及大电导率的机械敏感通道（MscL）和另一种较小电导率的机械敏感通道（MscS）。这些细菌力感应通道检测由渗透压触发的膜拉伸，并通过允许渗透剂的紧急喷射来保护细胞免于破裂。尽管在识别这些重要的通道方面取得了进展，但脊椎动物神经元中的机械转导通道的身份仍然难以捉摸。例如，尚未在哺乳动物中发现Nomp-C和Msc通道的直系同源物，并且支持Deg/ENaC在哺乳动物机械转导中的作用的证据有限。由于它是可能的，机械转导的分子机制是古老的，并在进化上保守的，我们假设，额外的机械转导通道尚未被确定。这个建议的目标是确定这些进化上保守的机械转导通道的候选人。为此，我们将：1）通过在机械感觉神经元中进行离子通道RNA的组织特异性RNAi敲低来测试预测的果蝇基因组的离子通道亚基在机械转导中起作用的假设。2)使用光遗传学技术将可能在转导步骤起作用的通道与在转导下游起作用的通道分开。3)开始对我们在前两个目标中确定的机械感觉离子通道进行详细的遗传分析。鉴定新的机械传导通道及其脊椎动物同源物可能会增加对从耳聋到疼痛的人类疾病的理解。 公共卫生相关性：鉴定新的机械传导通道及其脊椎动物同源物可能会增加对从耳聋到疼痛的人类疾病的理解。

DESCRIPTION (provided by applicant): A large body of evidence suggests that ion channels act as force sensors in mechanotransduction systems. In flies, the No mechanoreceptor potential-C (Nomp-C) channel has been suggested to be a force transduction channel in neurons that detect bristle deflection. In C. elegans, mechanotransduction channels of the Deg/ENaC family have been unambiguously identified as force sensors in touch neurons. The Mec10/Mec4 channel is the central component of a transduction complex that also involves extracellular matrix proteins. In bacteria, a simpler form of mechanotransduction involves a mechanosensitive channel of large conductance (MscL) and another of smaller conductance (MscS). These bacterial force-sensing channels detect membrane stretch triggered by osmotic pressure and protect the cell from rupture by allowing emergency ejection of osmolytes. Despite progress in identifying these important channels, the identities of mechanotransduction channels in vertebrate neurons remain elusive. For example, orthologs of Nomp-C and Msc channels have not been found in mammals and there is limited evidence supporting a role for Deg/ENaC's in mammalian mechanotransduction. Since it is likely that molecular mechanisms of mechanotransduction are ancient, and evolutionarily conserved, we hypothesize that additional mechanotransduction channels have yet to be identified. The goal of this proposal is to identify candidates for these evolutionarily conserved mechanotransduction channels. To achieve this we will: 1) Test the hypothesis that predicted ion channel subunits of the Drosophila genome function in mechanotransduction by performing tissue-specific RNAi knock down of the ion channel RNAs in mechanosensory neurons. 2) Use optogenetic techniques to separate channels that are likely to act at the transduction step from those that function downstream of transduction. 3) Begin detailed genetic analysis of the mechanosensory ion channels that we have identified in the first two aims. Identifying the novel mechanotransduction channels and their vertebrate homologues may lead to an increased understanding of human diseases ranging from deafness to pain. PUBLIC HEALTH RELEVANCE: Identifying the novel mechanotransduction channels and their vertebrate homologues may lead to an increased understanding of human diseases ranging from deafness to pain.