Dominant Connexin Mutations and Hearing Loss

描述（由申请人提供）：发现三种基因（GJB 2、GJB 3、GJB 6）编码间隙连接蛋白（分别为连接蛋白26（Cx 26）、（Cx 30）和（Cx 31）），可导致显性和/或隐性听力损失。这些突变如何导致听力损失仍然未知。虽然隐性突变体和显性突变体都有功能受损，但显性突变体可能对野生型对应物具有额外的显性负效应，甚至相互之间具有反式显性抑制效应，因为Cx 26，Cx 30和Cx 31都在耳蜗中表达。耳蜗细胞缝隙连接耦联的丧失可能影响内耳钾离子的稳态，导致听力障碍。为了检验这些假设，将产生细胞和动物模型以分析显性GJB 2/Cx 26、GJB 6/Cx 30和GJB 3/Cx 31突变的影响，具有以下三个具体目的：1）确定显性GJB 2/Cx 26、GJB 6/Cx 30和GJB 3/Cx 31突变对其同源突变蛋白在间隙连接缺陷型HeLa细胞中的组装、运输和功能的影响; 2）确定显性GJB 2/Cx 26、GJB 6/Cx 30和GJB 3/Cx 31突变对表达野生型人Cx 26、Cx 30和Cx 31的HeLa细胞的影响; 3）通过在耳蜗的间充质细胞中表达这些突变体来产生和分析所选显性GJB 2/Cx 26突变的动物模型。细胞和动物模型的运输和功能结果将阐明显性GJB 2/Cx 26、GJB 6/Cx 30和GJB 3/Cx 31突变的基本细胞和分子机制，并且选定突变的动物模型将作为进一步研究这些遗传性耳聋原因和治疗的基本资源。主要研究者提出了这五年的监督研究经验和教学培训，作为从临床医生到临床科学家的过渡期。谢勒博士曾对GJB 1/Cx 32突变的影响进行过类似的分析，她将与神经生物学和听觉生物学领域的知名研究者克伦肖博士一起沿着指导她的科学发展。这项工作将得到桑德斯博士的合作支持，桑德斯博士是听觉神经生物学和生理学方面的知名研究者。一个由连接蛋白和听觉生物学方面备受尊敬的专家组成的外部咨询委员会将提供额外的支持和建议。我的目标是成为一名训练有素的生物医学独立调查员。宾夕法尼亚大学优秀的学术环境和巨大的资源，以及她所在研究所的承诺将最大限度地发挥她的成功潜力。

DESCRIPTION (provided by applicant): Three genes (GJB2, GJB3, GJB6) encode for gap junction proteins (connexin 26 (Cx26), (Cx30) and (Cx31) respectively), are found to cause dominant and/or recessive hearing loss. How these mutations cause hearing loss remains unknown. While both recessive and dominant mutants have impaired function, the dominant mutants might have additional dominant negative effects on the wild type counterparts or even trans-dominant inhibition effects on each other, as Cx26, Cx30 and Cx31 are all expressed in the cochlea. The loss of gap junction coupling in cochlear cells may affect the homeostasis of potassium ions in the inner ear and cause hearing impairment. To test these hypotheses, cellular and animal models will be generated to analyze the effects of dominant GJB2/Cx26, GJB6/Cx30, and GJB3/Cx31 mutations, with the following three Specific Aims: 1) to determine the effects of dominant GJB2/Cx26, GJB6/Cx30, and GJB3/Cx31 mutations on the assembly, trafficking and function of their cognate mutant protein in gap junction-deficient HeLa cells; 2) to determine the effects of dominant GJB2/Cx26, GJB6/Cx30, and GJB3/Cx31 mutations on HeLa cells that express wild-type human Cx26, Cx30 and Cx31; 3) to generate and analyze animal models of selected dominant GJB2/Cx26 mutations, by expressing these mutants in the mesenchymal cells of the cochlea. The trafficking and functional results of the cellular and animal models will elucidate the fundamental cellular and molecular mechanism of dominant GJB2/Cx26, GJB6/Cx30, and GJB3/Cx31 mutations, and the animal models of selected mutations will serve as a fundamental resource for further study of the causes and treatments of these inherited causes of deafness. The principle investigator proposed this five year supervised research experience and didactic training to serve as a transitional period from a clinician to a clinician scientist. Dr. Scherer, who has performed similar analyses on the effects of GJB1/Cx32 mutations, will mentor her scientific development, along with Dr. Crenshaw, an established investigator in neurobiology and auditory biology. The work will be supported by the collaboration of Dr. Saunders, an established investigator in the neurobiology and physiology of hearing. An external advisory committee of highly regarded expert in connexin and auditory biology will provide additional support and advice. My goal is to become a well trained independent investigator in biomedicine. The excellent academic environment and the tremendous resource at the University of Pennsylvania, as well as the commitment of her institute will maximize her potential to succeed.