Role of Conventional Myosin MYH9 in Hearing

描述（由申请人提供）：通过候选基因方法，我们已经确定MYH 9为DFNA 17（一种常染色体显性遗传性非综合征型遗传性听力障碍）的致病基因。MYH 9是一种传统的非肌肉肌球蛋白，它加入了越来越多的与听力损失相关的肌球蛋白名单。在DFNA 17家族中，在高度保守的SHI接头区域内，核苷酸2114处的G至A转换将密码子705从不变的精氨酸（R）改变为组氨酸（H），R705 H。突变MYH 9与非综合征性听力障碍的共分离说明了MYH 9在听力中的生物学重要作用和与突变等位基因相关的器官特异性病理学。该研究的目的是了解MYH 9及其突变等位基因MYH 9 R7 O 5 H在听力及其功能障碍中的作用。我们将检验MYH 9对正常听力至关重要，突变等位基因MYH 9 R7 O 5 H导致肌球蛋白功能障碍和听力障碍的假设。首先，我们将评估MYH 9对人类听力的重要性。将对遗传病因不明的听力损失患者进行MYH 9基因突变筛查，以确定MYH 9突变在非综合征性听力障碍中的作用。额外突变的发现将促进基因型-表型相关性，并确定MYH 9对听力损失的贡献。其次，我们将评估MYH 9在内耳发育和听力中的作用。这将通过表征Myh 9在发育和成年小鼠内耳中的表达模式并确定其缺失的影响来进行。我们将使用携带标记基因插入其Myh 9等位基因的XA 1 36 ES细胞系来产生Myh 9无效等位基因的转基因小鼠。第三，我们将评估MYH 9 R7 O 5 H突变对体外和体内肌球蛋白功能的影响。将在体外表征MYH 9 R7 O 5 H的ATP酶活性、肌动蛋白依赖性运动性及其在已确定MYH 9生物学作用的培养细胞系中表达的影响。通过Myh 9 R705 H等位基因的靶向或随机种系引入产生DFNA 17的小鼠模型将评估MYH 9 R705 H在体内的作用。总之，拟议的研究将有助于阐明MYH 9在听力和耳聋中的作用。

DESCRIPTION (provided by applicant): Through the candidate gene approach, we have identified MYH9 as the causative gene responsible for DFNA17, an autosomal dominant nonsyndromic form of hereditary hearing impairment. MYH9, a conventional nonmuscle myosin, joins the growing list of myosins associated with hearing loss. In the DFNA17 family, a G to A transition at nucleotide 2114 changes codon 705 from an invariant arginine (R) to histidine (H), R705H, within a highly conserved SHI linker region. The co-segregation of the mutant MYH9 with nonsyndromic hearing impairment illustrates a biologically significant role for MYH9 in hearing and an organ-specific pathology associated with the mutant allele.The objective of the proposed research is to understand the role of MYH9 and its mutant allele MYH9R7O5H in hearing and its dysfunction. We will test the hypothesis that MYH9 is essential for normal hearing and that the mutant allele MYH9R7O5H leads to myosin dysfunction and auditory impairment. Initially, we will assess the importance of MYH9 to hearing in humans. Individuals with hearing loss of unknown genetic etiology will be screened for alterations in the MYH9 gene to determine the contribution of MYH9 mutations in nonsyndromic hearing impairment. The discovery of additional mutations will facilitate genotype-phenotype correlation and determining the contribution of MYH9 to hearing loss in general. Secondly, we will assess the role of MYH9 in inner ear development and hearing. This will be carried out by characterizing the expression pattern of Myh9 in the developing and an adult mouse inner ear and determining the effects of its absence. We will use the XA1 36 ES cell line carrying a marker gene insertion into its Myh9 allele to generate mice transgenic for the Myh9 null allele. Thirdly, we will assess the effect of the MYH9R7O5H mutation on myosin function in vitro and in vivo. MYH9R7O5H will be characterized in vitro for its ATPase activity, actin-dependent motility and the effect of its expression in cultured cell lines in which biological role of MYH9 has been established. Generating a mouse model of DFNA1 7 through targeted or random germline introduction of Myh9R7O5H allele will assess the effect of MYH9R7O5H in vivo. In summary, the proposed research will lead to elucidation of the role of MYH9 in hearing and deafness.