Neuron-Glia Interactions in the Cochlea

项目摘要 在这个项目中，我们将研究使耳蜗神经胶质细胞形成和维持的细胞和分子事件。 一生听力所需的听觉回路。与周围神经系统的其他神经胶质细胞一样，耳蜗神经胶质细胞 从神经脊发育而来，这是一个高度迁移和可塑性的祖细胞群体，产生神经元和 结缔组织以及卫星胶质细胞和雪旺细胞。尽管它们与其他外围设备起源相同 胶质细胞，即最终填充到耳蜗处的神经胶质细胞，具有一些独特的特性，这些特性对于感觉是必不可少的 对听力的影响，如将螺旋神经节神经元(SGN)胞体髓鞘形成的能力。此外，耳蜗神经胶质细胞 为高活性的SGN提供关键的营养支持，并清除多余的离子和递质 否则可能是破坏性的。最后，尽管神经胶质前体通常沿着轴突迁移，但在耳蜗里， 胶质前体细胞先于SGN神经突起迁移，似乎有助于有序放射状突起的有效形成 沿色调轴的束状物。我们的总体目标是了解耳蜗神经胶质细胞是如何获得这些特性的。基座 根据我们实验室和其他实验室的数据，我们假设转录因子GATA2和GATA3分别起作用 在发展神经胶质细胞和神经细胞，以协调耳蜗线和功能所需的相互作用。为了支持…… 根据这一观点，我们发现GATA2在耳蜗神经胶质细胞中表达，而在躯体感觉系统的神经胶质细胞中不表达。 此外，先前对Gata2突变小鼠的分析显示，听力障碍和SGN损失可能是由于 对神经胶质细胞的未知影响。另一方面，我们观察到GATA3突变的SGN延长了他们的 神经突起就像它们不能与神经胶质细胞相互作用一样，导致了类似于 发育中的耳蜗会耗尽胶质细胞。我们将利用分子技术对这些观察结果进行追踪 小鼠神经胶质组织的遗传学特征及其对SGN突起生长的影响 (目标1)，确定GATA2在耳蜗神经胶质细胞发育中的作用(目标2)，并比较GATA依赖 基因在SGN和神经胶质细胞中的表达程序(目标3)。对于目标1，我们将使用遗传和病毒方法来 可视化胶质细胞并破坏其与发育中的SGN神经突起相互作用的能力，如在固定组织和 通过时间推移成像。对于目标2，我们将从耳蜗神经胶质细胞中删除Gata2，并评估对耳蜗线的影响， 通过记录ABR来评估神经胶质细胞的分化和功能、SGN存活和听觉功能 和DPOAE。对于目标3，我们将对胚胎GATA2和GATA3突变耳蜗进行scRNA测序， 既是为了识别可能介导神经元-胶质细胞相互作用的下游基因，也是为了了解神经元和胶质细胞如何 在发育过程中相互影响。综上所述，这些研究将促进我们对耳蜗的了解 胶质细胞的发育和功能，对听力损失有直接影响，包括与Gata2相关的听力损失 (Emberger综合征)和GATA3(HDR综合征)突变。

Project Summary In this project, we will investigate the cellular and molecular events that allow cochlear glia to shape and sustain auditory circuits for a lifetime of hearing. Like the other glia of the peripheral nervous system, cochlear glia develop from the neural crest, a highly migratory and plastic population of progenitors that produce neurons and connective tissue as well as satellite glia and Schwann cells. Despite their common origin with other peripheral glia, the glia that ultimately populate the cochlea take on some unique properties that are essential for the sense of hearing, such as the ability to myelinate spiral ganglion neuron (SGNs) cell bodies. In addition, cochlear glia provide crucial trophic support for the highly active SGNs and also clear away excess ions and transmitter that could otherwise be damaging. Finally, whereas glial precursors generally migrate along axons, in the cochlea, the glial precursors migrate ahead of the SGN neurites and appear to facilitate efficient formation of orderly radial bundles along the tonotopic axis. Our overall goal is to learn how cochlear glia acquire these properties. Based on data from our lab and others, we hypothesize that the transcription factors Gata2 and Gata3 act separately in developing glia and SGNs to coordinate interactions needed for cochlear wiring and function. In support of this idea, we found that Gata2 is expressed by cochlear glia but not by glia of the somatosensory system. Additionally, previous analysis of Gata2 mutant mice revealed hearing deficits and SGN loss that could be due to unrecognized effects on the glia. On the other hand, we observed that Gata3 mutant SGNs extend their neurites as if they are unable to interact with the glia, resulting in disorderly wiring that mimics what occurs when glia are depleted from the developing cochlea. We will follow up on these observations by using molecular genetic approaches in the mouse to characterize glial organization and its effects on SGN neurite outgrowth (Aim 1), to determine the role of Gata2 in cochlear glia development (Aim 2), and to compare GATA-dependent programs of gene expression in SGNs and glia (Aim 3). For Aim 1, we will use genetic and viral approaches to visualize glia and disrupt their ability to interact with developing SGN neurites, as assessed in fixed tissue and by time-lapse imaging. For Aim 2, we will delete Gata2 from cochlear glia and assess effects on cochlear wiring, on glial differentiation and function, on SGN survival, and on auditory function, as assessed by recording ABRs and DPOAEs. For Aim 3, we will perform scRNA-sequencing of embryonic Gata2 and Gata3 mutant cochleas, both to identify downstream genes that may mediate neuron-glia interactions and to learn how neurons and glia are affected by each other during development. Together, these studies will advance our knowledge of cochlear glia development and function, with direct implications for hearing loss, including that associated with Gata2 (Emberger Syndrome) and Gata3 (HDR Syndrome) mutations in humans.