Notch Signaling Pathways in Auditory Supporting Cell Differentiation and Maintenance

项目摘要 听觉支持细胞（SC）对机械性神经元的正常发育、存活和功能至关重要。 感觉毛细胞（HC）及其支配神经元。SC的生物物理特性或功能缺陷 导致听觉功能障碍和听力损失。尽管它们的重要性， 它们的发展和功能在很大程度上是未知的。我们提出的研究的一个主要目标是揭示 引导听觉SC发育和功能的分子机制。我们最近发现 Notch信号指导小鼠耳蜗中SC的发育。在这项研究中，我们将 确定控制SC分化和存活（aim 1）的Notch配体和受体 表征Notch信号传导及其靶点在SC引导的耳蜗神经支配中的潜在新作用， 听觉功能（aim 2）。我们提出的研究将推进我们对Notch信号传导如何 在分化SC的威尔斯以及提供新的见解如何SC指导神经元的神经支配， 以及控制耳蜗内环境稳定。我们提出的研究的第二个主要目标是揭示 控制哺乳动物SC可塑性发育下降的分子机制 耳蜗哺乳动物的HC损失是永久性的，并且是人类耳聋的主要原因。在非- 哺乳动物脊椎动物SC在动物的一生中再生丢失的HC。在哺乳动物中， 通过抑制Notch信号或过度刺激wnt， 然而，小鼠听觉SC对这种再生刺激的反应能力迅速下降， 在产后第一周后。我们最近发现，RNA结合蛋白LIN 28 B增强HC 在未成熟的耳蜗中响应Notch信号的产生。在aim 3中，我们将研究LIN 28 B/let- 7轴改变未成熟SC的再生反应，以及解决LIN 28 B是否重新激活。 在成熟SC中的表达增强了它们响应Notch抑制和再生丢失的HC的能力。 拟议实验的结果可以确定新的治疗靶点，并导致新的治疗方法。 治疗HC丧失和最终治愈耳聋的方法。

Project summary Auditory supporting cells (SCs) are essential for the proper development, survival and function of mechano- sensory hair cells (HCs) and their innervating neurons. Defects in the biophysical properties or function of SCs result in auditory dysfunction and hearing loss. Despite their importance the molecular mechanisms that control their development and function are largely unknown. A main objective of our proposed study is to uncover the molecular mechanisms that guide auditory SCs development and function. We recently uncovered that Notch signaling instructs SC development in the murine cochlea. Here in this proposed study we will determine the Notch ligand(s) and receptor(s) that control SC differentiation and survival (aim1) as well characterize potential novel roles for Notch signaling and its targets in SC-guided cochlear innervation and auditory function (aim2). Our proposed studies will advance our understanding of how Notch signaling operates in differentiating SCs as wells as provide new insights into how SCs guide neuronal innervation as well as control cochlear homeostasis. A second major objective of our proposed study is to uncover the molecular mechanisms that control the developmental decline of SCs plasticity in the mammalian cochlea. HC loss in mammals is permanent and is a leading cause for deafness in humans. In non- mammalian vertebrates SCs regenerate lost HCs throughout the lifetime of the animal. In mammals, young immature SCs can be coaxed into regenerating lost HCs by inhibiting Notch signaling or over-stimulation of wnt signaling; however, the ability of murine auditory SC to respond to such regenerative stimuli rapidly declines after the first postnatal week. We recently uncovered that the RNA binding protein LIN28B enhances HC production in the immature cochlea in response to Notch signaling. In aim3 we will investigate how LIN28B/let- 7 axis modifies the regenerative response of the immature SCs, as well as address whether LIN28B re- expression in mature SCs enhances their ability to respond to Notch inhibition and regenerate lost HCs. Findings from the proposed experiments could identify new therapeutic targets and lead to novel therapeutic approaches in the treatment of HC loss and eventual cure of deafness.