Connexin Mutations in Deafness

描述(申请人提供)：人类连接蛋白26基因突变 (Cx26或GJB2)是美国非综合征性耳聋的主要原因 各州。另外两个连接蛋白基因Cx30(GJB6)和Cx3l(GJ63)的突变， 在人类身上也会造成听力损失。虽然这说明了一个关键的功能 对于耳蜗缝隙连接，尚不清楚常见的病理是如何发生的 来自不同连接蛋白基因的突变，这些基因具有重叠 内耳的表达模式，如Cx26、Cx30和Cx31的情况。 人类的感觉毛细胞之间没有缝隙连接； 相反，它们在耳蜗的支持细胞中表达。海流 假说是这些连接在血液循环中起作用 内淋巴和外淋巴之间的钾离子。很难调和 该模型与现有的钾在缝隙结中的渗透数据相结合 通道，因为所有的连接蛋白都很容易被这种阳离子渗透和丢失 一个单一的耳蜗连接蛋白仍将留下两个功能连接蛋白 来执行这项任务。缝隙连接蛋白确实表现出对广泛的 一系列其他小分子和第二信使，我们假设 这些通透性差异对耳蜗功能至关重要，甚至更多 难以补偿三人中的一人的功能丧失 可用通道子单元。此应用程序的目标是准确地 确定Cx26的哪些渗透特性是正常听觉所必需的 在人类身上起作用。为了实现这一目标，我们首先提出了筛选突变体Cx26 非洲爪哇卵母细胞配对分析中的功能活性等位基因。Cx26突变体 然后将保留通道功能的基因导入哺乳动物细胞系， 并用双膜片钳方法分析了它们的渗透选择性特性。 比较野生型和致病型的渗透性差异 Cx26的变体不仅将提供对听力损失的机械性洞察， 但也将为连接蛋白多样性的需要提供一个通用的模型 人类疾病由连接蛋白基因突变引起的其他组织。

DESCRIPTION (provided by applicant): Mutations in the human connexin 26 gene (Cx26, or GJB2) are the leading cause of nonsyndromic deafness in the United States. Mutations in two additional connexin genes, Cx30 (GJB6) and Cx3l (GJ63), also produce hearing loss in humans. While this illuminates a critical function for cochlear gap junctions, it is not clear how a common pathology can arise from mutations within different connexin genes that have an overlapping expression pattern in the inner ear, as is the case for Cx26, Cx30 and Cx3l. There are no gap junctions present between the sensory hair cells in humans; rather they are expressed in the supporting cells of the cochlea. The current hypothesis is that these junctions play a role in the re-circulation of potassium ions between the endolymph and perilymph. It is difficult to reconcile this model with the available data on potassium permeation through gap junction channels, as all connexins are readily permeated by this cation and the loss of a single cochlear connexin would still leave two functional connexins available to perform this task. Connexins do show differential permeability to a wide range of other small molecules and second messengers, and we hypothesize that these permeation differences are critical for cochlear function, and more difficult to compensate for following the functional loss of one of the three available channel subunits. The objective of this application is to precisely define which permeation properties of Cx26 are necessary for normal auditory function in humans. To achieve this goal, we first propose to screen mutant Cx26 alleles for functional activity in the paired Xenopus oocyte assay. Cx26 mutants that retain channel function will then be transfected into mammalian cell lines, and have their permselectivity properties analyzed by dual patch clamp methods. Contrasting the differences in permeation between wildtype and disease causing variants of Cx26 will not only provide mechanistic insight into hearing loss, but will also provide a general model for the need for connexin diversity in other tissues where human disease results from mutations in connexin genes.