Molecular and functional characterization of type I and II vestibular hair cells in adult mice

项目摘要 哺乳动物前庭器官的感觉感受器，称为毛细胞，编码头部的运动 并沿着前庭神经将信息传递到脑干和小脑。哺乳动物有两种类型的 毛细胞分为I型和II型，具有不同的形态和生理特性。I型和II型毛细胞 也有不同形式的传入神经分布在上皮区。 前庭毛细胞在正常衰老和暴露于耳毒素后死亡，这种损失可能导致严重的 前庭缺陷。成年小鼠前庭毛细胞损伤后，支持细胞再生约50%的II型 毛细胞，但没有I型毛细胞被替换。这种自然的毛细胞再生并不能恢复 前庭系统功能恢复正常，如通过前庭-眼反射和其他行为测试。 对这一发现的一种解释是，哺乳动物的I型毛细胞必须被取代，才能发挥前庭功能 回去吧。虽然这很容易推测，但几乎没有证据表明特定的I型毛细胞是必需的。 前庭功能。事实上，我们对I型和II型毛细胞分别对 我们的前庭感觉。 解决这个难题的一个步骤是使用分子生物学来更好地理解独特的 以确定每种毛细胞类型的特征，并确定是否存在I型和II型毛细胞亚型。与戴维斯博士一起工作。 尼尔·塞吉尔和陶礼涛，我从单细胞RNA测序中发现，似乎有四个分子 成年小鼠卵圆囊内毛细胞的不同种群：两种类似L的种群，一种类似于L1的种群， 和一组未知的毛细胞。在目标1中，我将继续这些研究，检查 所有前庭器官的候选细胞特异性基因，以确定是否可以识别四个不同的毛细胞组 以及这些群是如何分布在上皮区的。我将产生新的见解来 跨前庭器官的毛细胞特征，为每种细胞类型分类新的标记，并识别可能 在未来的研究中被用来驱动细胞选择性基因的错误表达。向测试不同的 I型和II型毛细胞的功能是去除每个毛细胞群并评估对前庭的影响 功能。在目标2中，我将使用CreLoxP技术来消融所有的I型毛细胞或外周I型毛细胞 所有的成人前庭器官。我将确定这些消融对动物行为和脑干的影响 对前庭刺激的电反应，据我所知，这在成年小鼠身上还没有做过。我 期望对I型毛细胞的一般功能和I型毛发的特殊功能有新的见解 各上皮区的细胞。总体而言，这项研究提供了关于血管紧张素转换酶特性和功能的新信息 I型和II型毛细胞，并告知治疗平衡障碍的新疗法。此外，这个项目使我能够 在使用尖端科学方法的协作环境中接受一流的研究培训。

Project Abstract The sensory receptors for mammalian vestibular organs, called hair cells, encode head movements and relay information along the vestibular nerve to the brainstem and cerebellum. Mammals have two types of hair cell, type I and type II, which different morphological and physiological properties. Type I and II hair cells also have distinct forms of afferent innervation that are differentially distributed across the epithelial zones. Vestibular hair cells die during normal aging and after exposure to ototoxins, and this loss can lead to profound vestibular deficits. After vestibular hair cell damage in adult mice, supporting cells regenerate ~50% of type ll hair cells, but no type I hair cells are replaced. This natural hair cell regeneration does not restore the vestibular system to normal function, as measured by the vestibulo-ocular reflex and other behavioral tests. One interpretation of this finding is that type I hair cells must be replaced in mammals for vestibular function to return. While this is tempting to speculate, there is little evidence that type I hair cells are required for specific vestibular functions. Indeed, we understand little about the respective contributions of type I and II hair cells to our vestibular sense. One step toward solving this puzzle is to use molecular biology to better understand the unique features of each hair cell type and to determine if subtypes of type I and II hair cells exist. Working with Drs. Neil Segil and Litao Tao, I found from single cell RNA sequencing that there seem to be four molecularly distinct populations of hair cells in adult mouse utricles: two type l-like populations, one type ll-like population, and one unknown group of hair cells. In Aim 1, I will continue these studies, examining expression of candidate cell-specific genes in all vestibular organs to determine if four distinct hair cell groups are identifiable in each organ and how these groups are distributed across epithelial zones. I will generate novel insights into hair cell features across vestibular organs, classify new markers for each cell type, and identify genes that may be used to drive cell-selective gene misexpression in future studies. Another step toward testing the different functions of type I and II hair cells is to remove each hair cell population and assess impacts on vestibular function. In Aim 2, I will use CreLoxP technology to ablate all type I hair cells or peripheral type I hair cells in all adult vestibular organs. I will determine the impact of these ablations upon animal behaviors and brainstem electrical responses to vestibular stimuli, which to my knowledge has not been done before in adult mice. I expect to gain new insights into the general function of type I hair cells and the specific functions of type I hair cells in each epithelial zone. Overall, this research provides new information about properties and functions of type I and II hair cells and inform on new therapies to treat balance disorders. Further, this project enables me to receive top-notch research training in a collaborative setting using cutting-edge scientific approaches.