The role of transcription factors and chromatin remodeling proteins in spiral ganglion neuron regeneration

 描述(申请人提供)：由螺旋神经节神经元(SGN)丢失引起的听神经病导致听力损失。标准的补救措施，如使用助听器和人工耳蜗，在SGN丢失后是无效的。许多日常的耳毒性侮辱，如响亮的声音，会导致突触接触的急性丧失，听觉神经纤维的退化，并在较长时间内失去SGN。鉴于不断增长的老龄化人口暴露在便携式音乐播放器的嘈杂声音中，SGN的退化将成为一个主要的健康问题。干细胞替代疗法很有希望重新填充丢失的SGN，恢复听力功能。为了正确使用干细胞治疗听力损失，识别能够重现干细胞中SGN发育的基因将加速替代疗法的努力。利用永生化的耳祖细胞(IMOP)细胞系，我们确定了在SGN发育和再生中重要的新的候选转录因子和染色质重塑蛋白。候选基因之一是CHD4，这是一种染色质重塑蛋白，是核小体重塑和脱乙酰酶(NuRD)复合体的一部分。我们认为，CHD4在SGN发育过程中对神经元的指定、轴突的引导和突触的形成是必不可少的。我们将使用iMOP来源的神经元和内耳CHD4基因敲除动物来测试CHD4在确定神经元命运和轴突延伸方面的作用。利用iMOP来源的神经元和去传入的耳蜗外植体共培养系统，我们将研究CHD4如何促进轴突对毛细胞靶点的引导。最后，我们将产生一个他莫昔芬诱导的CHD4基因敲除动物，以确定SGN成熟过程中突触发生的缺陷。

 DESCRIPTION (provided by applicant): Auditory neuropathy caused by the loss of spiral ganglion neurons (SGN) loss results in hearing loss. Standard remediation, such as the use of hearing aids and cochlear implants are ineffective after the loss of SGNs. Many daily ototoxic insults such as loud sounds result in acute loss of synaptic contacts, degeneration of the auditory nerve fibers and loss of SGN over an extended period of time. Given an ever-increasing aging population that is exposed to loud sounds from portable music players, degeneration of SGNs will become a major health concern. Stem cell replacement therapies hold great promise to repopulate lost SGNs and restore hearing function. In order to properly use stem cells to treat hearing loss, identifying genes that can recapitulate SGN development in stem cells will accelerate efforts for replacement therapies. Using an immortalized otic progenitor (iMOP) cell line, we identified novel candidate transcription factors and chromatin remodeling proteins that are important in SGN development and regeneration. One of the candidates is Chd4, a chromatin remodeling protein that is part of the nucleosome remodeling and deacetylase (NuRD) complex. We propose that Chd4 is essential for neuronal specification, axon guidance and synaptogenesis during SGN development. We will test the role of Chd4 in specifying neuronal fate and neurite extension using iMOP-derived neurons and an inner ear Chd4 knockout animal. Using an iMOP-derived neuron and deafferented cochlear explant co-culture system, we will study how Chd4 promotes axon guidance to the hair cell targets. Finally, we will generate a tamoxifen inducible Chd4 knockout animal to determine defects in synaptogenesis during SGN maturation.