Mechanisms that regulate hair cell survival

调节毛细胞存活的机制

• 批准号: 9266774
• 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/9266774
• 关键词: Adolescent; Adult; Age; Aging; American; Apoptosis; Auditory; Cell Death; Cell Survival; Cells; Cochlea; Data; Development; Ectopic Expression; Exposure to; Genes; Hair Cells; 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; ototoxicity; overexpression; postnatal; prevent; public health relevance; 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）：当听觉毛细胞（HC）丢失时，它们在人类或其他成熟哺乳动物中不会被替换，导致永久性听力损失。相反，听觉HC的再生自然发生在非哺乳动物中，允许听力功能的恢复。我们最近观察到新生小鼠耳蜗在损伤后可以自发再生其毛细胞，然而，这些再生的细胞大多死亡。此外，许多研究表明，外部HC（OHC）比内部HC（IHC）更容易受到噪声或耳毒性药物引起的损害。然而，使OHC更加脆弱的机制还不清楚。在分化完成后，在正常条件下调节HC存活的途径也缺乏了解。拟议的研究将调查HC的生存在出生后的成熟和成年期，在HC再生，并在强调HC以下噪声暴露。我们将专注于一个基因，Pou4f3，一个转录因子，表达在毛细胞开始分化。虽然Pou4f3在发育过程中维持HC存活的作用以前被发现，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。初步数据显示，在成年OHC中Pou4f3的缺失导致细胞死亡，这表明成熟OHC仍然需要Pou4f3表达才能存活。此外，POU4F3免疫染色结果显示，许多成年OHC的POU4F3表达水平降低，而IHC保持强POU4F3表达。这些数据表明，POU4F3的完全缺失导致HC死亡，但POU4F3水平的降低足以维持HC存活。目的1将通过在新生儿、青少年和成人HC中删除Pou4f3来进一步研究这一点。此外，大多数新生小鼠耳蜗中自发形成的再生HC不表达POU4F3，我们假设这会导致细胞死亡。为了支持这一假设，另一项研究在支持细胞中异位表达Atoh1，将其转化为HC。这些新形成的HC存活至少3个月，并表达POU4F3。这些数据暗示Pou4f3在分化过程中调节HC存活，并且Aim 2将通过Pou4f3的异位表达来拯救新生小鼠耳蜗中的再生HC。由于已知Pou4F3调节参与细胞凋亡的几个基因，因此成年小鼠OHC中POU4F3表达水平的降低可能使这些细胞在应激条件下更脆弱，并导致OHC损伤易感性增加。我们将在目标3中通过过表达Pou4f3来保护OHC免受噪声诱导的损伤来测试这一假设。集体提出的研究将调查Pou4f3的作用，在正常的，未受损的耳蜗，在新生小鼠耳蜗自发HC再生过程中的成熟和成年期的HC生存的调节，并在强调HC噪声暴露后。这些目标的完成将促进我们对在多种条件下调节HC存活的机制的理解，这些机制可用于开发保护HC的药物。