Mechanisms of Sensory Hair Cell Death and Survival

描述（由申请人提供）：感觉毛细胞对噪声、衰老和某些治疗药物诱导的死亡过敏。两大类耳毒性药物是氨基糖苷类抗生素和顺铂。我们计划利用一种独特的成年小鼠椭圆囊的体外制备，使我们能够在分子水平上研究耳毒性毛细胞死亡和存活的机制。了解这些细胞机制对于设计旨在预防或逆转听力损失的疗法至关重要。热休克蛋白（Heat Shock Proteins，HSPs）是细胞应激反应中普遍存在的一种高度保守的反应，在某些系统中可显著抑制细胞凋亡。热休克蛋白的诱导发生在毛细胞响应于各种刺激。然而，目前还没有研究热休克蛋白对耳毒性药物诱导的毛细胞死亡的影响。更重要的是，目前还没有关于毛细胞中热休克蛋白和凋亡蛋白在任何刺激下的细胞相互作用的数据。我们的初步数据表明，在体外热休克处理抑制毛细胞死亡的新霉素和顺铂暴露。本实验旨在验证热休克对耳毒性药物诱导的毛细胞死亡的保护作用是HSP介导的特异性凋亡信号通路抑制的结果这一假设。提出了四组实验：1）。研究介导顺铂与氨基糖苷类药物诱导毛细胞死亡的分子机制之间的相似性和差异。2）。确定热休克处理是否足以诱导耳毒性药物浓度和毛细胞存活之间的剂量-反应关系发生变化。3）。目的：探讨热休克对耳毒性毛细胞凋亡的保护作用是否需要诱导HSP-70的表达。4）。探讨耳毒性药物暴露后毛细胞中热休克蛋白与凋亡蛋白的相互作用。

DESCRIPTION (provided by applicant): Sensory hair cells are hypersensitive to death induced by noise, aging, and some therapeutic drugs. Two major classes of ototoxic drugs are the aminoglycoside antibiotics and the antineoplastic agent cisplatin. We plan to take advantage of a unique in vitro preparation of the adult mouse utricle that allows us to examine the rrechanisms underlying ototoxic hair cell death and survival at the molecular level. Understanding these cellular mechanisms will be critical for the design of therapies aimed at preventing or reversing hearing loss. The induction of heat shock proteins (HSPs) in response to cellular stress is a ubiquitous and highlyconserved response that can significantly inhibit apoptosis in some systems. Induction of HSPs occurs in hair cells in response to a variety of stimuli. However, there are no studies on the effects of HSPs on ototoxic drug-induced hair cell death. More importantly, there are no data available regarding the cellular interactions between HSPs and apoptotic proteins in hair cells in response to any stimulus. Our preliminary data demonstrate that in vitro heat shock treatment inhibits hair cell death in response to both neomycin and cisplatin exposure. The experiments in this proposal are designed to test the hypothesis that the protective effect of heat shock against ototoxic drug-induced hair cell death is the result of HSP-mediated inhibition of specific apoptotic signaling pathways. Four groups of experiments are proposed: 1). To examine the similarities and differences between the molecular mechanisms mediating cisplatin- vs. aminoglycoside-induced hair cell death. 2). To determine whether heat shock treatment is sufficient to induce a shift in the dose-response relationship between ototcxic drug concentration and hair cell survival. 3). To determine whether induction of HSP-70 is necessary and sufficient for the protective effect of heat shock against ototoxic hair cell apoptosis. 4). To investigate the interactions between HSPs and apoptotic proteins in hair cells exposed to ototoxic drugs.