MYOSIN I BETA AND INNER EAR STRUCTURE/FUNCTION

描述：毛细胞使用一种适应机制，以确保其 转导通道在它们的最佳灵敏度点工作。 确定负责以下的蛋白质的分子身份 适应是重要的，原因有几个：首先，这种识别 应该可以帮助我们发现转导的其他成员 设备. 第二，因为毛细胞是如此稀缺的材料来源， 为了研究，鉴定出负责的基因将使我们能够表达 其蛋白质丰富的生化和生物物理研究。 最后， 人类的适应性是否来自编码适应性的突变基因 马达或相关蛋白质，未来的基因替代疗法采用 功能性基因可能会纠正这种缺陷。 最佳人选 毛细胞的适应马达是肌球蛋白IB，一种非传统的肌球蛋白 在静纤毛顶端发现的同工酶。 因为毛细胞 很少，因为发束位移直接打开转导 通道，证明肌球蛋白IB是适应电机使用生化 方法是非常困难的，如果不是不可能的话，获得。 测试 无论肌球蛋白IB是否真的是适应马达，我们都将排除 它的基因从小鼠的基因组中，并研究其对听觉和 随之而来的前庭功能。 因为完全敲除肌球蛋白IB 基因可能具有广泛的影响，这可能会混淆我们评估其 在特定的适应作用下，我们还将在转基因小鼠中表达突变体 肌球蛋白基因应该对适应有可预测的影响。 这 该提案利用了三个实验室的优势：美世 实验室，在小鼠遗传学和分子生物学方面具有丰富的经验 克隆，以及吉莱斯皮和科里实验室，具有优势，在 生化分析和生理评估的适应， 两栖动物和哺乳动物的毛细胞。 这里提出的实验将 直接测试肌球蛋白IB是否确实是毛细胞的适应马达。

DESCRIPTION: Hair cells use an adaptation mechanism to ensure that their transduction channels operate at their point of optimal sensitivity. Determination of the molecular identity of proteins responsible for adaptation is important for several reasons: First, such identification should assist us in attempts to discover other members of the transduction apparatus. Second, because hair cells are such a scarce source of material to study, identification of the responsible gene will permit us to express its protein in abundance for biochemical and biophysical studies. Finally, should human deafnesses derive from mutated genes encoding the adaptation motor or associated proteins, future gene-replacement therapies employing a functional gene could conceivably correct such deficits. The best candidate for the hair cell's adaptation motor is myosin IB, an unconventional myosin isozyme that is found at stereociliary tips. Because hair cells are so scarce and because hair-bundle displacements directly open transduction channels, proof that myosin IB is the adaptation motor using biochemical methods is extremely difficult, if not impossible, to obtain. To test whether myosin IB is indeed the adaptation motor, we will instead eliminate its gene from the mouse's genome, and study the consequences on auditory and vestibular function that ensue. Because a complete knockout of myosin IB's gene may have broad effects that may confound our ability to assess its specific role in adaptation, we will also express in transgenic mice mutant myosin genes that should have predictable effects on adaptation. This proposal draws on the strengths of three laboratories: the Mercer laboratory, with extensive experience in mouse genetics and molecular cloning, and the Gillespie and Corey laboratories, with strengths in biochemical analysis and physiological assessment of adaptation in both amphibian and mammalian hair cells. The experiments proposed here will directly test whether myosin IB is indeed the hair cell's adaptation motor.