Auditory Neurogenetics

描述（由申请人提供）：听力损失是使人衰弱和永久性的，影响< 66%的70岁以上的人口（Cruickshanks等人，Am. J. Epidemiol.，1998年），造成人际孤立，并有重大的财务影响。 在上一个资助期，我们使用定位克隆技术分别鉴定了小鼠突变体的Atp 2b 2和Spnb 4的突变（Streetea，1998; Parkinson ea，2001）。对于每个基因座，我们确定了多个等位基因与不同程度的功能障碍。对于Waddler，dfw等位基因是功能降低至30%的亚型（Penheiter ea），而dfw 2 J和dfvv 3 J是明显的无效等位基因，具有移码突变，不产生可检测的蛋白质。我们发现所有等位基因的纯合突变体都是耳聋的（Konrad-Martin，2001 ; Mccullough and Tempel，submitted）。进一步的研究表明，在纯合缺失小鼠（dfw 2 J/dfw 2 J）中，内淋巴钙浓度从对照的23 μ/M下降到6 μ/M（Wood等人，2004年）。内淋巴钙的这种显著下降可能与深度耳聋、耳石变性和丧失有因果关系（Fonseca-Burke et al.，在编写中），以及毛细胞损失（Pujol等人，2001）在纯合的无效Waddler等位基因中。在杂合子中，未观察到毛细胞损失，但听力损失发生频率较高（Konrad-Martin，2001; McCullough和Tempel，已提交）。 这些数据表明，钙在内耳中受到严格调节，PMCA 2（Atp 2b 2基因座的蛋白质产物）是维持钙平衡的关键因素。在这里，我们建议扩展我们的研究，通过检查其对年龄相关性听力损失（阿勒）和噪声性听力损失（NIHL）的小鼠Atp 2b 2表达的分级降低的贡献。为了建立比较人与小鼠的基本原理，我们将检查PMCA 2在人颞骨中的分布，并询问携带ATP 2B 2位点缺失的患者是否表现出听力损失。为了确定预防听力损失的药理学策略，我们将研究Atp 2b 2基因调控的分子基础，并询问Atp 2b 2表达水平的增加是否可以预防小鼠阿勒并保护其免受NIHL。

DESCRIPTION (provided by applicant): Hearing loss is debilitating and permanent, affecting < 66% of the population over age 70 (Cruickshanks et al., Am. J. Epidemiol., 1998), causing interpersonal isolation and having significant financial impact. During the previous funding period, we used positional cloning techniques to identify mutations in Atp2b2 and Spnb4 in the mouse mutant's deafwaddler and quivering, respectively (Street ea, 1998; Parkinson ea, 2001). For each locus we identified multiple alleles with different degrees of functional impairment. For deafwaddler, the dfw allele is a hypomorph with function reduced to 30% (Penheiter ea) while dfw 2J and dfvv 3J are apparent null alleles with frameshift mutations yielding no detectable protein. We have found that homozygous mutants of all alleles are deaf (Konrad-Martin, 2001 ; Mccullough and Tempel, submitted). Further studies have shown that in homozygous null mice (dfw2J/dfw 2J) endolymphatic calcium concentration drops from 23 mu/M in control to 6 mu/M (Wood et al., 2004). This significant drop in endolyphatic calcium may be causally related to profound deafness, to the degeneration and loss of otoconia (Fonseca-Burke et al., in prep.), as well as to hair cell loss (Pujol et al., 2001) in homozygous null deafwaddler alleles. In heterozygotes no hair cell loss is seen yet hearing loss occurs at high frequencies (Konrad-Martin, 2001; McCullough and Tempel, submitted). These data suggest that calcium is tightly regulated in the inner ear and that PMCA2 (the protein product of the Atp2b2 locus) is a critical player in maintaining calcium balance. Here we propose to extend our studies on deafwaddler by examining its contribution to age-related hearing loss (AHL) and noise-induced hearing loss (NIHL) in mice with graded reductions in Atp2b2 expression. To establish a rationale for comparing man with mouse, we will examine the distribution of PMCA2 in human temporal bone and ask whether patients carrying a deletion of the ATP2B2 locus show hearing loss. Toward identifying pharmacological strategies for preventing hearing loss, we will examine the molecular basis of Atp2b2 gene regulation and ask whether increased levels of expression of Atp2b2 can prevent AHL in mice and protect them from NIHL.