Mechanisms that regulate hair cell survival

调节毛细胞存活的机制

• 批准号: 9026273
• 负责人: Brandon C. Cox
• 金额: $ 31.34万
• 依托单位: SOUTHERN ILLINOIS UNIVERSITY SCH OF MED
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-01 至 2021-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9026273
• 关键词: Accounting; Adolescent; Adult; Age; Aging; American; Apoptosis; Auditory; Cell Death; Cell Survival; Cells; Cochlea; Data; Development; Ectopic Expression; Exposure to; Genes; Hair Cells; Health; Hearing; Human; Inherited; Injury; Inner Hair Cells; Knockout Mice; Link; Longevity; Mammals; Measures; Mus; Mutate; Mutation; Natural regeneration; Neonatal; Noise; Outer Hair Cells; Pathway interactions; Pattern; Pharmaceutical Preparations; Physiological; Predisposition; Process; Recovery; Regulation; Role; Stress; Supporting Cell; Testing; United States; deafness; differential expression; disability; effective therapy; hair cell regeneration; hearing impairment; overexpression; postnatal; prevent; therapy development; transcription factor; transcriptome; treatment strategy

 DESCRIPTION (provided by applicant): When auditory hair cells (HCs) are lost, they are not replaced in humans or other mature mammals, resulting in permanent hearing loss. In contrast, regeneration of auditory HCs naturally occurs in non-mammals, allowing for recovery of hearing function. We have recently observed that the neonatal mouse cochlea can spontaneously regenerate its HCs after damage; however, the majority of these regenerated cells died. In addition, many studies have shown that outer HCs (OHCs) are more susceptible than inner HCs (IHCs) to damage caused by noise or ototoxic drugs. Yet the mechanism that makes OHCs more vulnerable is not understood. There is also a lack of understanding of the pathways that regulate HC survival under normal conditions after differentiation is complete. Proposed studies will investigate HC survival during postnatal maturation and adulthood, during HC regeneration, and in stressed HCs following noise exposure. We will focus on one gene, Pou4f3, a transcription factor that is expressed in HCs beginning with differentiation. While the role of Pou4f3 in maintaining HC survival during development was discovered previously, its role in postnatal maturation, aging, regeneration, and in stressed HCs has not been explored. Preliminary data show that deletion of Pou4f3 in adult OHCs causes cell death which suggests that mature OHCs still require Pou4f3 expression to survive. In addition, POU4F3 immunostaining results show that many adult OHCs have decreased levels of POU4F3 expression, while IHCs retained strong POU4F3 expression. These data suggest that complete deletion of POU4F3 causes HCs to die, but reduced levels of POU4F3 are enough to maintain HC survival. Aim 1 will investigate this further by deleting Pou4f3 in neonatal, juvenile, and adul HCs. In addition, the majority of regenerated HCs that spontaneously form in the neonatal mouse cochlea do not express POU4F3 and we hypothesize that this causes cell death. In support of this hypothesis, another study ectopically expressed Atoh1 in supporting cells to convert them into HCs. These newly formed HCs survived at least 3 months and did express POU4F3. These data implicate Pou4f3 in the regulation of HC survival during the differentiation process and Aim 2 will rescue regenerated HCs in the neonatal mouse cochlea by ectopic expression of Pou4f3. Since Pou4f3 is known to regulate several genes involved in apoptosis, decreased levels of POU4F3 expression in OHCs of adult mice may make these cells more vulnerable under stressful conditions and account for the increased damage susceptibility of OHCs. We will test this hypothesis in Aim 3 by over-expressing Pou4f3 to protect OHCs from noise-induced damage. Collectively proposed studies will investigate Pou4f3's role in the regulation of HC survival during maturation and adulthood in the normal, undamaged cochlea, during spontaneous HC regeneration in the neonatal mouse cochlea, and in stressed HCs following noise exposure. Completion of these aims will advance our understanding of the mechanisms that regulate HC survival under multiple conditions, which could be used to develop drugs to protect HCs.

 描述（由申请人提供）：当人类或其他成熟哺乳动物的听觉毛细胞（HC）丢失时，它们不会被替换，从而导致永久性听力损失。相反，听觉毛细胞的再生在非哺乳动物中自然发生，从而允许听力损失。我们最近观察到，新生小鼠的耳蜗在受损后可以自发再生，但这些再生的细胞大部分都死亡了。 HC (OHC) 比内部 HC (IHC) 更容易受到噪音或耳毒性药物造成的损害，但对于正常情况下调节 HC 存活的机制尚不清楚。拟议的研究将调查出生后成熟和成年期、HC 再生期间以及噪声暴露后应激 HC 中的 HC 存活率。虽然之前已发现 Pou4f3 在发育过程中维持 HC 存活的作用，但其在出生后成熟、衰老、再生和应激 HC 中的作用尚未被探索。成体 OHC 会导致细胞死亡，这表明成熟的 OHC 仍需要 Pou4f3 表达才能生存。此外，POU4F3 免疫染色结果表明，许多成体 OHC 的水平下降。 POU4F3 表达，而 IHC 保留强烈的 POU4F3 表达。这些数据表明，POU4F3 的完全删除会导致 HC 死亡，但 POU4F3 水平的降低足以维持 HC 的存活，目标 1 将通过删除新生儿、青少年和成年动物中的 Pou4f3 来进一步研究这一点。此外，新生小鼠耳蜗中自发形成的大多数再生 HC 不表达 POU4F3。为了支持这一假设，另一项研究在支持细胞中异位表达 Atoh1 以将其转化为 HC，这些新形成的 HC 存活了至少 3 个月，并且确实表达了 POU4F3。分化过程中 HC 的存活率和 Aim 2 将通过 Pou4f3 的异位表达来拯救新生小鼠耳蜗中再生的 HC。已知调节参与细胞凋亡的多个基因，成年小鼠 OHC 中 POU4F3 表达水平的降低可能使这些细胞在压力条件下更脆弱，并解释了 OHC 损伤敏感性增加的原因，我们将在目标 3 中通过过度测试来检验这一假设。表达 Pou4f3 以保护 OHC 免受噪音损伤新生小鼠耳蜗的自发 HC 再生过程以及噪声暴露后受压的 HC 的研究将促进我们对多种条件下调节 HC 存活的机制的理解，这可用于开发保护 HC 的药物。