Hair Cell Development in the Mammalian Cochlea

听觉和前庭功能依赖于功能性内耳的形成。虽然这两个系统都有多个组成部分，但该实验室的重点是感觉上皮的发育，其中包含机械感觉毛细胞和称为支持细胞的相关细胞，以及来自第VIII（听前庭）的神经元对这些毛细胞的神经支配。脑神经。所有这三种细胞类型都来源于耳囊，耳囊是一种在发育早期邻近后脑形成的基板结构。确定指定这些细胞类型中的每一种的因素，然后指导它们组装成功能单元，是发育神经科学部分的关键目标。在过去的一年里，实验室的不同成员已经检查了这些发展过程的几个不同方面。 实验室的整体活动受到2020年3月开始的强制关闭的重大影响。 然而，我们能够发表一个长期项目的结果，该项目试图使用单细胞RNA测序在多个时间点表征发育中耳蜗内的所有细胞类型。 在这项研究中，我们从四个不同的发育时间点（E14，E16，P0和P7）收集了超过30，000个细胞。 对这些细胞的后续分析揭示了新的细胞类型，并使我们能够生成已知细胞（如毛细胞）和新细胞类型（如位于Kollikers器官中的细胞）的发育轨迹，Kollikers器官是一种短暂的发育结构，与耳蜗的几个独特方面有关。 我们还确定了一种新的信号通路，由转化生长因子β调节，对Corti器官内两种独特细胞类型的发育至关重要，即外毛细胞和Deiters细胞。 该项目正在进行的工作已经开始产生更完整地表征TGF β作用所需的条件性小鼠突变体。 根据NIH基因组数据共享政策，我们将所有单细胞数据存放在两个存储库中，即GEO和gestival Portal，这是一个为共享内耳单细胞数据而设计和维护的在线网站。 gestro跟踪数据使用情况，我们很高兴看到这一数据集得到广泛使用。 我们还发表了第二个单细胞RNA-Seq研究，其中我们比较了出生后早期和成年支持细胞。 结果表明，基因表达的变化作为支持细胞的发展，但也表明，两个独特的支持细胞类型存在于新生儿和成人耳蜗。 这些数据也存放在地球观测组织和地球观测卫星中。 作为正在进行的合作的一部分，我们参与了研究NAD+补充剂对Cockayne综合征小鼠模型（一种早衰样模型）毛细胞存活的影响的项目，并研究了雅普在哺乳动物椭圆囊毛细胞再生中的作用。

Auditory and vestibular function are dependent of the formation of a functional inner ear. While there are multiple components for both of these systems, this laboratory focuses on the development of the sensory epithelia, which contain mechanosensory hair cells and associated cells called supporting cells and on the innervation of those hair cells by neurons from the VIIIth (acousticovestibular) cranial nerve. All three of these cell types are derived from the otocyst, a placodal structure that forms adjacent to the hindbrain early in development. Identifying the factors that specify each of these cell types and then direct their assembly into functional units is a key goal of the Section on Developmental Neuroscience. During the previous year, different members of the laboratory have examined several different aspects of these developmental processes. Overall activity in the laboratory was significantly affected by the mandatory shutdown beginning in March, 2020. However, we were able to publish the results of a long-term project which sought to characterize all of the cell types within the developing cochlea at multiple time points using single cell RNA-sequencing. In this study, we collected just over 30,000 cells from four different developmental time points, E14, E16, P0 and P7. Subsequent analysis of these cells revealed novel cell types and allowed us to generate developmental trajectories for both known cells, such as hair cells, and novel cell types, such as those located in Kollikers organ, a transient developmental structure that has been implicated in the generation of several unique aspects of the cochlea. We also identified a novel signaling pathway, regulated by Transforming Growth Factor Beta, as important for the development of two unique cell types within the organ of Corti, outer hair cells and Deiters cells. Ongoing work on this project has begun to generate the conditional mouse mutants required to more completely characterize the role of TGF Beta. In compliance with the NIH Genome Data Sharing Policy, we deposited all of our single cell data in two repository, GEO and the gEAR Portal, an online site designed and maintained for the purpose of sharing inner ear single cell data. gEAR tracks data usage and we have been very happy to see extensive use of this data set. We also published a second single cell RNA-Seq study in which we compared early post-natal and adult supporting cells. Results indicated changes in gene expression as supporting cells develop but also showed that two unique supporting cell types are present in both newborn and adult cochleae. These data were also deposited in both GEO and gEAR. As part of ongoing collaborations, we contributed to projects examining the effects of NAD+ supplementation on hair cell survival in mouse models of Cockayne syndrome, a progeria-like model of premature aging, and examined the role of YAP in hair cell regeneration in the mammalian utricle.