Myosin 15 Genetics, Pathology and Therapeutic Potential

遗传性内耳疾病很普遍，对生活质量有重大影响。目前临床上还没有治疗遗传性内耳疾病的方法。小鼠是了解遗传性内耳疾病和开发治疗措施的理想哺乳动物模型。小鼠模型促进了人类遗传疾病基因的发现，使研究这些基因在内耳发育和功能中的作用成为可能，并为开发遗传性内耳疾病的治疗方法提供了很大的希望。这项资助申请建立在我们的发现之上，即非常规肌球蛋白基因Myo15的突变导致了患有DFNB3的人类和两种患有严重隐性耳聋的小鼠自发性突变体shaker 2和shaker 2J的深度先天性耳聋。我们拟利用这两种DFNB3小鼠模型来建立这种大肌球蛋白的结构和功能特性、在子宫和产后早期生活中的表达需求以及患病个体的病理发育基础。随着这些目标的实现，我们将更接近儿童先天性耳聋基因治疗的最终目标，并扩大我们对基本听力过程的分子理解。在第一个目标中，我们将严格测试通过与BAC转基因互补完成的摇锤2小鼠耳聋表型纠正的长期功能和结构结果。第二个目的是验证MYOSIN xv缺陷毛细胞在发育过程中不能脱离基底膜，从而导致细胞病理的假设。第三个目的是检查Myo15功能的丧失是否部分由其他肌凝蛋白的功能补偿。第四个目的是用转基因小鼠检测MYOXV蛋白异常的n端3对功能是否重要。最后，我们将利用Myo15转基因在幼龄、产后摇鼠2中诱导表达的方法来评估DFNB3基因治疗新生儿或幼儿的可行性。我们的研究团队拥有跨学科合作的成果记录，其中包括耳鼻喉科和形态学的专业知识以及分子和发育遗传学的专业知识。我们的跨学科方法对于充分利用动物模型至关重要，这将是开发和测试遗传性内耳疾病治疗的基础。

Hereditary inner ear disease is prevalent and has significant implications for quality of life. There is currently no available clinical cure for hereditary inner ear disease. The mouse serves as an ideal mammalian model for understanding genetic inner ear disease and for developing therapeutic measures. Mouse models have facilitated the discovery of genes that underlie hereditary disease in humans, have made it possible to study the role of these genes in inner ear development and function, and hold great promise as models for developing treatments for hereditary inner ear disease. This grant application builds on our discovery that mutations in the unconventional myosin gene, Myo15, are responsible for profound congenital deafness in humans with DFNB3 and in two spontaneous mouse mutants with profound recessive deafness, shaker 2 and shaker 2J. We propose to use these two mouse models of DFNB3 to establish the structure and functional properties of this large myosin, the requirement for expression in utero and early postnatal life, and the developmental basis for pathology in affected individuals. As each of these goals are accomplished we will move closer toward the ultimate objective of gene therapy for congenital deafness in children and expand our molecular understanding of the basic hearing process. In the first aim, we will rigorously test the long-term functional and structural outcome of the phenotypic correction of deafness in shaker 2 mice that we accomplished by complementation with a BAC transgene. The second aim tests the hypothesis that MYOSIN XV-deficient hair cells fail to detach from the basement membrane during development, leading to cellular pathology. The third aim examines whether loss of Myo15 function is partially compensated by the function of other myosins. The fourth aim tests whether the unusual N-terminal third of the MYOXV protein is important for function using transgenic mice. Finally the feasibility of gene therapy for DFNB3 in newborns or young children will be assessed in the last aim using inducible expression of Myo15 transgenes in young, postnatal shaker 2 mice. Our investigative team has a track record for accomplishments resulting from cross disciplinary collaboration, which has brought expertise in otolaryngology and morphology together with expertise in molecular and developmental genetics. Our interdisciplinary approach is essential to fully exploit the animal models that will be the basis for developing and testing therapy for hereditary inner ear disease.