Cell Type Specific Transcriptional Cascades in Inner Ear Development

 描述（由申请人提供）：遗传性非综合征性听力损失影响1：500的新生儿，年龄相关性听力损失困扰着大多数老年人。在大多数形式的听力损失中，毛细胞（HC）变性是一种常见的最终途径。我们研究的长期目标是破译内耳发育所必需的细胞类型特异性转录和信号级联，并应用这些知识来识别：（a）听力所必需的基因;（B）分化的有效调节因子，最终可用于恢复听力。ATOH 1是HC命运的主要调节因子，其可能通过激活一系列转录因子（TF）以及非调节基因来发挥作用。然而，ATOH 1的强制表达在聋耳中不足以产生成熟的听觉毛细胞。因此，迫切需要鉴定介导新形成的HC分化的信号级联。在这个提议中，我们专注于GFI 1和RFX TF，其在果蝇中的直系同源物是ATOH 1直系同源物的直接靶点。我们最近确定了一个进化保守的作用，ciliogenic RFX蛋白在调节新生小鼠HC特异性转录组，并确定Rfx 3和Rfx 7作为最丰富的Rfx转录在HC。在特定目标1中，我们将使用条件性基因敲除小鼠确定RFX在HC分化中的作用，并鉴定和验证HC中RFX调节的靶基因。在具体目标2中，我们将确定GFI 1的分子靶点，GFI 1是外部HC存活和前庭HC分化所必需的基因，并验证新确定的靶点在体内的作用。为了促进在公共领域中传播本提案和其他提案中产生的数据，并作为建立内耳细胞类型特异性分化所需的转录网络的一步，我们将建立和维护gene-听觉研究门户网站。

 DESCRIPTION (provided by applicant): Hereditary non-syndromic hearing loss affects 1:500 newborns and age related hearing loss afflicts the majority of the elderly population. In most forms of hearing loss, hair cell (HC) degeneration is a common final pathway. The long-term goal of our research is to decipher the cell type-specific transcriptional and signaling cascades that are necessary for inner ear development, and to apply this knowledge to identify: (a) genes necessary for hearing; and (b) potent regulators of differentiation, which could ultimately be used to restore hearing. ATOH1 is a master regulator of HC-fate that likely functions through the activation of a series of transcription factors (TFs) as well as non-regulatory genes. However, forced expression of ATOH1 in deafened ears is not sufficient to generate mature auditory HCs. Therefore, there is a critical need to identify the signaling cascades mediating the differentiatio of newly formed HCs. In this proposal we focus on the GFI1 and RFX TFs, whose orthologs in Drosophila are immediate targets of the ATOH1 ortholog. We recently identified an evolutionarily conserved role for the ciliogenic RFX proteins in regulating the newborn mouse HC-specific transcriptome, and identified Rfx3 and Rfx7 as the most abundant Rfx transcripts in HCs. In Specific Aim 1 we will determine the role of RFX in HC differentiation using conditional knockout mice, and identify and validate the RFX-regulated target genes in HCs. In Specific Aim 2 we will identify the molecular targets of GFI1, a gene necessary for outer HC survival and vestibular HC differentiation, and validate the roles of newly identified targets in vivo. In orderto facilitate dissemination of data generated in this and other proposals in the public domain, and as a step towards building the transcriptional networks necessary for inner ear cell type-specific differentiation, we will build and maintain the gEAR - a gene Expression for Auditory Research portal.