Elucidation of Under-Investigated Biological Mechanisms of Age-Related Hearing Loss

摘要 这项提案将建立一个关于自噬和年龄相关性听力损失(ARHL)的概念验证； 是一种在我们日益增长的老龄化人口中非常普遍的沟通和神经感觉障碍，影响 全球数亿美元，每年在管理和干预方面花费数十亿美元。 临床干预在许多方面都特别具有挑战性，因为急性淋巴细胞性白血病的机制并不是 安全。这一提议具有很高的创新性，因为它旨在对新的 突破性策略，基于年龄相关的听觉系统自噬变化和 急性淋巴细胞性白血病的进展。在正在进行的实验中，我们发现了与年龄相关的自噬积累 哺乳动物耳蜗中的标记，如Lc3和P62。我们的体内周转实验表明， 自溶体形成过程中可能存在自噬通量胁迫。我们还发现，抑制自噬 通透性降低膜上Na，K-ATPase(NKA)和氯化钠的表达 共转运蛋白(NKCC1)在SV细胞系(SV-K1)中。这是两个关键的离子通道，维持 正常听力的耳蜗电(EP)。鉴于我们的新发现，我们假设衰老可能会影响 与年龄相关的自噬应激对耳蜗感觉神经和新陈代谢的影响。因此，我们 建议进行循序渐进的细胞机制研究，以全面了解 老年耳蜗内的自噬现象。这项建议的目的有三个：第一，我们将确定 自噬应激是否是听力损失的一般特征。几种自噬抑制剂将被用来 对幼年CBA/CAJ小鼠进行处理，检测其听力和生物标志物的变化。第二, 自噬通量应激在耳蜗中的功能作用，包括年龄相关的细胞凋亡和SV相关的离子 将对渠道活动进行调查。第三，我们将确定目标步骤(S)在自噬通量上的老化 对耳蜗产生影响，为未来ARHL的干预探索原创、可行的方法。这 预计该项目将为ARHL的生物学机制的未知领域提供新的见解，以及 解开许多谜团，不仅有助于更好地了解耳蜗老化过程，而且还将 促进制定更复杂和有效的急性淋巴细胞性白血病的预防和治疗方案。

ABSTRACT This proposal will establish a proof-of-concept relating autophagy and age-related hearing loss (ARHL); which is a highly-prevalent communication and neurosensory disorder of our expanding aging population, affecting hundreds of millions worldwide, and costing billions of dollars annually for management and interventions. Clinical interventions are particularly challenging in many ways, because the mechanisms of ARHL are not clear. This proposal is highly innovative because it aims to carry out translational research for new breakthrough strategies, based upon links between age-related autophagy changes in the auditory system and the progression of ARHL. In ongoing experiments, we have found age-related accumulations of autophagy markers such as LC3 and p62 in the mammalian cochlea. Our in vivo turnover experiments showed that an autophagic flux stress may exist in autolysosomal formation steps. We also found that inhibition of autophagy flux decreased the membrane expressions of Na,K-ATPase (NKA) and sodium potassium chloride cotransporter (NKCC1) in the SV-cell line (SV-K1). These are the two key ion channels that maintain the endocochlear potential (EP) for normal hearing. Given our new findings, we hypothesis that aging may affect sensory, neural and metabolic aspects of the cochlea through age-related autophagic stress. Therefore, we propose to carry out step-by-step cellular mechanism studies to yield a comprehensive view of the role of autophagy in the aged cochlea. The aims of this proposal are threefold: First, we are going to determine whether autophagy stress is a general feature of hearing loss. Several autophagy inhibitors will be used to treat young adult CBA/CaJ mice and their hearing abilities and biomarker changes will be measured. Second, the functional roles of autophagy flux stress in the cochlea, including age-related apoptosis and SV-related ion channel activity will be investigated. Third, we will identify target step(s) in autophagic flux on which aging exerts influences in the cochlea, and explore original, feasible ways for future interventions for ARHL. This project is expected to provide novel insights into unknown areas of the biological mechanisms of ARHL, and resolve many of the mysteries that will not only fuel a better understanding of cochlear aging process, but will facilitate the development of more sophisticated and effective prevention and treatment options for ARHL.