INNER EAR GAP JUNCTIONS FOR HEARING

该项目的长期目标是研究Corti器官中的间隙连接耦合如何对正常听力做出贡献。耳蜗非感觉细胞间广泛存在间隙连接偶联。感觉细胞（内毛细胞和外毛细胞）之间或感觉细胞和支持细胞之间没有间隙连接偶联。内耳间隙连接的紊乱与非综合征性耳聋的高发有关。耳蜗间隙连接的假设功能可能涉及营养、离子和小分子的通道以及维持耳蜗内电化学梯度。缝隙连接通道由连接蛋白组成；每个细胞侧有6个连接蛋白亚基。在耳蜗中已鉴定出5种以上的连接蛋白基因。宏观电流（包含多个通道）的记录表明，支持细胞中的间隙结耦合具有跨结电压（Vj）依赖性和膜电位（Vm）依赖性。这表明通道结构复杂。本研究的具体目的是通过单通道记录来识别耳蜗支持细胞中间隙连接通道的类型。双电压钳技术将用于记录单通道活动。跨结电流将在弱耦合的细胞对上测量，或使用解偶联剂，如CO2和辛醇，以减少细胞耦合。单通道电导，动力学和电压依赖于任何一方的电池将检查，以确定通道配置。乙酰胆碱（Ach）和环核苷酸将应用于细胞以测试可能的门控调节。这些研究结果可能为内耳间隙连接通路的功能提供线索，并提高我们对其对正常哺乳动物听力的贡献的理解。这一信息可能对医生治疗由连接蛋白突变引起的耳聋患者具有临床意义。

The long-term goal of this project is to investigate how gap junctional coupling in the organ of Corti contributes to normal hearing. Gap junctional coupling is extensive between the cochlear non-sensory cells. There is no gap junctional coupling between sensory cells (inner and outer hair cells) or between sensory cells and supporting cells. Disturbances of inner ear gap junctions are known to be associated with a high incidence of non-syndromic deafness. Hypothetical functions of gap junctions in the cochlea may involve nutrition, passage of ions and small molecules, and maintaining intracochlear electrochemical gradients. A gap junction channel is composed of connexin proteins; each cell side has 6 connexin subunits. More than 5 connexin genes have been identified in the cochlea. Recording of macroscopic current (containing many channels) has demonstrated that gap junctional coupling in supporting cells has variables transjunctional voltage (Vj) dependence and membrane potential (Vm) dependence. This indicates complex channel constitutions. The specific objective in this proposal is to identify types of gap junctional channels in the cochlear supporting cells by single channel recording. A double voltage clamp technique will be used to record the single channel activity. Transjunctional current will be measured on weakly coupled cell pairs or using uncoupling agents, such as CO2 and octanol, to diminish the cell coupling. Single channel conductance, kinetics and voltage dependence on either cell side will be examined to identify the channel configuration. Acetylcholine (Ach) and cyclic nucleotide will be applied to cells to test the possible gating regulation. The results of these studies may provide clues as to functional gap junctional pathways in the inner ear, and improve our understanding of their contributions to normal mammalian hearing. This information may be clinically relevant for physicians treating patients with deafness induced by connexin mutations.