Basic Mechanisms in Hearing Loss of Cochlear Origin

描述(由申请人提供)： 目的：感音神经性听力损失(SNHL)与包括冲击伤在内的兵役多方面因素密切相关。这项提案的目的是改善退伍军人SNHL的预防和治疗。研究设计：为了更好地理解毛细胞(HC)损伤和丢失背后的细胞过程，将通过测定分子异构体的表达和评估基因敲除小鼠的HC丢失来评估分子异构体在已知的HC损伤和生存途径中的作用。为了改善SNHL的预防，还将确定能够保护耳蜗HCS免受损害的药物。为了改进SNHL的治疗，将识别能够增强Atoh1诱导哺乳动物耳蜗非感觉细胞转化为HCS的转录因子。此外，还将研究对基因沉默机制的修改，以确定无感觉内耳细胞采用HC表型特征的表观遗传学限制。方法：使用体外培养的内耳感觉上皮细胞进行研究，并在体内研究噪声对耳蜗组织的损伤。为了鉴定HC保护剂和转录因子，创新的高通量方法已经被开发出来，以允许快速但有针对性地筛选药物和诱导哺乳动物耳蜗上皮细胞中的基因表达。在过去的资助期取得的进展：已经确定了耳毒素进入HC的机制；已经确定了进入HC的细胞模式；已经确定了保护HC的两条新的细胞内途径；已经确定了三种导致耳聋的基因突变；已经确定了HC发育的一个关键期，在这个关键期中，已经确定了两种可以促进无感觉耳蜗细胞向HC转化的新的转录因子；已经进行了对耳蜗感觉上皮的表观遗传操作，以增强由病毒载体诱导的基因表达。临床关系：SNHL的预防和治疗对退伍军人和退伍军人非常重要。SNHL对退伍军人生活质量的影响是巨大的。在退伍军人中，SNHL和耳鸣也比其他任何疾病占更多的残疾补偿，而且康复费用很高。拟议的研究旨在开发新的和改进的疗法来预防和治疗这一重要的健康问题。

DESCRIPTION (provided by applicant): Objectives: Sensorineural hearing loss (SNHL) is strongly associated with many aspects of military service including blast injury. The objectives of this proposal are to improve the prevention and treatment of SNHL in veterans. Research Design: To improve our understanding of cellular processes underlying hair cell (HC) damage and loss, the contributions of molecular isoforms within known HC damage and survival pathways will be evaluated by determining their expression, and by evaluating HC loss in gene knockout mice. To improve SNHL prevention, pharmaceutical agents that can protect cochlear HCs from damage will also be identified. To improve treatment for SNHL, transcription factors that enhance the ability of Atoh1 to induce the conversion of mammalian cochlear non-sensory cells into HCs will be identified. In addition, modifications to mechanisms of gene silencing will be studied to identify epigenetic limitations on the ability of nonsensory inner ear cells to adopt features of the HC phenotype. Methodology: Studies will be performed using in vitro cultures of inner ear sensory epithelia, and in vivo studies of noise damage to the cochlea. For identification of HC protectants and transcription factors, innovative high-throughput methods have been developed to permit rapid, but targeted, screening of pharmaceuticals and induced gene expression in mammalian cochlear epithelia. Progress over the past period of funding: Mechanisms of ototoxin entry into HCs have been identified; cellular patterns of reactive oxygen species accumulation into HCs have been determined and antioxidant treatments evaluated; two novel intracellular pathways of HC protection have been defined; three gene mutations that lead to deafness have been identified; a critical period of HC development in which transplantation is possible has been determined; two novel transcription factors that enhance the conversion of nonsensory cochlear cells into HCs have been identified, and epigenetic manipulation of the cochlear sensory epithelium to enhance gene expression induced by a viral vector has been performed. Clinical Relationship: The prevention and treatment of SNHL is of great importance to veterans and to the VA. The effects of SNHL on veterans' quality of life are substantial. SNHL and tinnitus also account for more disability compensation in the VA than any other disorder, and rehabilitation costs are high. The proposed research is targeted at developing new and improved therapies for prevention and treatment of this important health problem.