The cell cycle in ototoxin induced hair cell death.

描述（由申请方提供）：该提案基于新观察结果，即抗生素给药后毛细胞中的细胞周期机制被激活。我们推测，这种细胞周期折返密切参与调节随后的毛细胞死亡。细胞周期机制在应激反应和细胞死亡中的重要性已得到充分证实。我们早期的工作表明，细胞周期机制，特别是细胞周期蛋白依赖性激酶（CDK）抑制剂p19lnk4d，在维持毛细胞的非分裂状态，从而在调节耳毒性应激和随后的死亡的敏感性的作用。本提案中提出的初步结果证实了这一建议。响应于新霉素，观察到细胞周期的激活。此外，细胞周期机制的抑制剂显示在施用氨基糖苷类抗生素后阻断细胞死亡。 为了追求这些观察结果，我们提出了三个具体的目标，结合药理学和遗传学的方法。在特异性目的1中，将检测阻断特异性细胞周期蛋白依赖性激酶（CDK）活性对耳毒素应答的影响。在具体目标2中，我们将重点关注毛细胞对耳毒素的反应，并试图在分子水平上将这种反应与细胞周期的激活联系起来。最后，在具体目标3中，我们提出了实验来验证这一假设，即在重新进入细胞周期时，毛细胞激活“下游”DNA损伤检查点，这是细胞死亡机制的近端诱导物。 感觉毛细胞的丧失是人类耳聋的主要原因。成熟的哺乳动物耳蜗不能再生其感觉毛细胞的补充，因此目前，由于感觉毛细胞损失而导致的耳聋的唯一治疗方法是使用假体，例如助听器和耳蜗植入物。保护毛细胞免受耳毒素诱导的细胞死亡的策略将允许更积极地使用化疗剂和抗生素治疗感染，这些感染现在受到它们已知的耳毒性副作用的限制。

DESCRIPTION (provided by applicant): This proposal is based on the novel observation that the cell cycle machinery in hair cells is activated following antibiotic administration. We hypothesize that this cell cycle reentry is intimately involved in regulating the subsequent cell death of hair cells. The importance of the cell cycle machinery in stress responses and cell death is well established. Our earlier work suggested a role for the cell cycle machinery, in particular the cyclin-dependent kinase (CDK) inhibitor p19lnk4d, in maintaining the non-dividing state of hair cells and thus in regulating the sensitivity to ototoxic stress and subsequent death. Preliminary results presented in this proposal confirm this suggestion. In response to neomycin, activation of the cell cycle is observed. In addition, inhibitors of the cell cycle machinery are shown to block cell death following administration of aminoglycoside antibiotics. To pursue these observations, we propose three specific aims incorporating a combined pharmacological and genetic approach. In Specific Aim 1, the effect of blocking specific cyclin-dependent kinase (CDK) activity on response to ototoxin will be tested. In Specific Aim 2, we will focus on the response of hair cells to ototoxins and attempt to tie this response to the activation of the cell cycle at the molecular level. Finally, in Specific Aim 3 we propose experiments to test the hypothesis that upon reentry into the cell cycle, hair cells activate the 'downstream' DNA damage checkpoint and that this is the, proximal inducer of the cell death machinery... Loss of sensory hair cells is the leading cause of deafness in humans. The mature mammalian cochlea cannot regenerate its complement of sensory hair cells and thus at present, the only treatment for deafness due to sensory hair cell loss is the use of prosthetics such as hearing aids and cochlear implants. Strategies to protect hair cells from ototoxin induced cell death would allow more aggressive use of chemotherapy agents and antibiotic treatment of infections that are now limited'by -their known ototoxic side effects.