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）丧失引起的听觉神经病导致听力丧失。标准的补救措施，如使用助听器和人工耳蜗在失去sgn后是无效的。许多日常耳毒性损伤，如大声的声音，会导致突触接触的急性丧失，听神经纤维的退化和长时间的SGN丧失。考虑到不断增加的老龄化人口暴露于便携式音乐播放器的大声声音中，sgn的退化将成为一个主要的健康问题。干细胞替代疗法在重新填充失去的sgn和恢复听力功能方面具有很大的前景。为了正确地使用干细胞治疗听力损失，识别能够在干细胞中重现SGN发育的基因将加速替代疗法的努力。利用一种永生化祖细胞（iMOP）细胞系，我们发现了在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。其中一个候选是Chd4，一种染色质重塑蛋白，是核小体重塑和去乙酰化酶（NuRD）复合体的一部分。我们认为，在SGN发育过程中，Chd4对神经元规范、轴突引导和突触发生至关重要。我们将使用iop衍生的神经元和内耳Chd4敲除动物来测试Chd4在指定神经元命运和神经突延伸中的作用。利用imop来源的神经元和失传入耳蜗外植体共培养系统，我们将研究Chd4如何促进轴突引导到毛细胞靶点。最后，我们将产生一个他莫昔芬诱导的Chd4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.