Genetic Regulation of Inner Ear Formation

内耳形成的遗传调控

• 批准号: 6926125
• 负责人: Monte Westerfield
• 金额: $ 44.56万
• 依托单位: UNIVERSITY OF OREGON
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-08-01 至 2009-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6926125
• 关键词: biological signal transduction; cell cell interaction; developmental genetics; developmental neurobiology; genetic mapping; genetic regulation; genetic screening; histogenesis; labyrinth; mutant; neurogenesis; point mutation; zebrafish

DESCRIPTION (provided by applicant): The long-term goal of this research is to understand how cells are specified to form the ear and how these processes are affected in human hearing diseases. The inner ear arises from the otic placode that forms at the lateral edge of the neural plate adjacent to the hindbrain. Current theories suggest that inductive signals from neighboring tissues are specify formation of the placode. However, it is unknown how cells are allocated to the placode or how they respond to the inductive signals that trigger their differentiation into the ear. Previous studies identified and analyzed two sets of transcription factor pairs, DIx3b/4b and Sox9a/9b that interact in a genetic pathway to specify otic placode cells. This pathway is regulated by Fgf3/8 signals from the adjacent hindbrain. The proposed studies will test the hypothesis that DIx3b/4b function is required for cells to become competent to respond to Fgf3/8 inductive signaling and that Fgf3/8 directs convergence and epithelialization of otic precursor cells. The proposed studies will test whether DIx3b/4b is sufficient for otic competence by examining whether ectopic Fgf3/8 induces placodes only where DIx3b/4b is expressed and whether Fgf3/8 beads induce otic markers in cells that normally Inever contribute to the if cells forced to DIx3b/4b. To learn how DIx3b/4b is ear, these ectopic are express expression regulated by factors that control dorsoventral patterning; functions of Bmps, Chordin and their downstream targets will be altered. These experiments will provide a mechanistic understanding of how cells become competent to form the ear. The proposed studies will test whether Fgf3/8 directs the morphogenetic movements and epithelialization of otic precursor cell. They will test whether Fgf3/8 is required for these processes by examining embryos in which Fgf3/8 function is blocked by mutation and morpholino treatment. They will test whether Fgf3/8 is sufficient by learning whether Fgf3/8 beads induce ectopic convergence and/or epithelialization. These experiments will elucidate the link between induction and cellular morphogenesis and provide new insights into how cells are specified to form the ear. A genetic screen of mutant phenotypes will identify additional genes required for induction of the otic placode. These mutations will be characterized phenotypically with mosaic analyses and gene expression analyses in whole-mount embryos and with microarrays to learn how each gene functions, when function is critical and in which cells function is required. The mutations will be characterized genetically by mapping, by complementation testing with existing mutations, and by molecular cloning. This analysis will identify, on the basis of their functions, the critical genes required for formation of the otic placodes.

描述（由申请人提供）：本研究的长期目标是了解细胞是如何被指定形成耳朵的，以及这些过程如何在人类听力疾病中受到影响。内耳起源于耳基板，耳基板形成于邻近后脑的神经板的外侧边缘。目前的理论认为，来自邻近组织的感应信号是基板形成的具体原因。然而，尚不清楚细胞如何分配到基板或它们如何响应触发它们分化成耳的诱导信号。先前的研究鉴定并分析了两组转录因子对，DIx 3b/4 b和Sox 9a/9 b，它们在遗传途径中相互作用以指定耳基板细胞。该途径受来自邻近后脑的Fgf 3/8信号调节。拟定的研究将检验以下假设：细胞需要DIx 3b/4 b功能才能对Fgf 3/8诱导信号做出反应，并且Fgf 3/8指导耳前体细胞的会聚和上皮形成。 拟定的研究将通过检查异位Fgf 3/8是否仅在表达DIx 3b/4 b的地方诱导基板，以及Fgf 3/8珠是否在通常不参与迫使细胞表达DIx 3b/4 b的细胞中诱导耳标志物，来测试DIx 3b/4 b是否足以用于耳感受态。为了了解DIx 3b/4 b是如何在耳中表达的，这些异位表达受控制背腹图案形成的因素的调节; Bmps，Chordin及其下游靶点的功能将被改变。这些实验将提供一个机制的理解细胞如何成为有能力形成耳朵。 拟开展的研究将检测Fgf 3/8是否指导耳前体细胞的形态发生运动和上皮形成。他们将通过检查Fgf 3/8功能被突变和吗啉代处理阻断的胚胎来测试这些过程是否需要Fgf 3/8。他们将通过了解Fgf 3/8珠是否诱导异位会聚和/或上皮形成来测试Fgf 3/8是否足够。这些实验将阐明诱导和细胞形态发生之间的联系，并为细胞如何形成耳朵提供新的见解。 突变表型的遗传筛选将鉴定诱导耳基板所需的其他基因。这些突变将通过镶嵌分析和整装胚胎中的基因表达分析进行表型表征，并通过微阵列了解每个基因如何发挥功能，何时功能至关重要以及需要哪些细胞发挥功能。突变将通过作图、与现有突变的互补测试和分子克隆进行遗传表征。该分析将根据其功能鉴定形成耳基板所需的关键基因。