Regulation of inner ear development by FGF signals and effectors

FGF 信号和效应器调节内耳发育

• 批准号: 10552052
• 负责人: Suzanne L Mansour
• 金额: $ 41.41万
• 依托单位: UNIVERSITY OF UTAH
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-02-05 至 2026-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10552052
• 关键词: Ablation; Address; Affect; Age; Auditory; Candidate Disease Gene; Cell Differentiation process; Cell Survival; Cells; Cochlea; Cochlear implant procedure; Data; Defect; Development; Dominant-Negative Mutation; Doxycycline; Epithelium; Equilibrium; FGF10 gene; FGF3 gene; Fibroblast Growth Factor; Fibroblast Growth Factor Receptors; Future; Ganglia; Generations; Genes; Goals; Health Care Costs; Hearing; In Vitro; Individual; Investigation; Knockout Mice; Knowledge; Labyrinth; Ligands; Maintenance; Mediating; Mesenchymal; Messenger RNA; Molecular; Morphogenesis; Morphology; Mus; Neurons; Otic Placodes; Pattern; Phenotype; Proliferating; Receptor Protein-Tyrosine Kinases; Regulation; Repression; Role; Sensory; Signal Pathway; Signal Repression; Signal Transduction; Signaling Molecule; Specific qualifier value; System; Testing; Tissues; Transplantation; cell type; combinatorial; conditional knockout; conditional mutant; extracellular; fibroblast growth factor receptor 2b; gene function; genetic approach; genome-wide analysis; hearing impairment; hearing restoration; in vivo; inner ear development; light intensity; loss of function; malformation; molecular marker; mouse model; mutant; nerve supply; neural; neuroblast; neurogenesis; novel; otoconia; overexpression; permanent hearing loss; social; spiral ganglion; transcription factor

Morphogenesis of the inner ear epithelium requires coordinated deployment of several signaling pathways and disruptions cause abnormalities of hearing and/or balance. With the advent of cochlear implantation to treat hearing loss even in cases of inner ear malformation, it is critical to understand exactly how such malformations affect the auditory ganglia and innervation. Also, in light of the intense focus on in vitro generation of inner ear cell types for transplantation and in vivo manipulation of developmental signaling molecules to promote differentiation of various inner ear cells for hearing restoration, elucidating the roles and regulation of such signals and their effectors governing otic differentiation and morphogenesis are necessary to advance treatment. The genes encoding FGF3 and FGF10, ligands that signal through FGFR2b and FGFR1b, are expressed dynamically throughout otic development in both epithelial and ganglion domains. Studies conducted by the Mansour Lab of both conventional Fgf3 and Fgf10 conditional knockout mice and those expressing a doxycycline-inducible ligand trap (dnFGFR2b) that rapidly inhibits signaling through both FGFR1b and FGFR2b, showed that Fgf3 and Fgf10 are not required in the placode lineage for otocyst formation, but are required subsequently for otocyst patterning, neuroblast maintenance, epithelial proliferation and both vestibular and cochlear morphogenesis. Furthermore, the first genome wide analyses of otocyst mRNA revealed FGFR2b/1b signaling targets that define novel candidates for genes involved in otic morphogenesis and function. This proposal has two Aims addressing the hypotheses that 1) FGFR2b/1b signaling is required continuously for both otic neuroblast specification and maintenance, and that at later stages, mesenchymal signaling, as well as that in the epithelial and ganglion domains, is required for cochlear epithelial differentiation and ganglion maintenance and 2) FGFR2b/1b downstream target genes mediate some or all of the effects of FGFR2b/1b signaling on otic morphogenesis and gangliogenesis. To determine the early role of FGFR2b/1b signaling in otic ganglion formation and its later role in epithelial differentiation and ganglion maintenance, DOX-induced ubiquitous and CRE-limited expression of dnFGFR2b will be employed and morphology and molecular markers of otic patterning, proliferation and survival in both tissues will be assessed. To determine the roles of downstream targets of FGFR2b/1b signaling, two genes encoding transcription factors that are activated by FGFR2b/1b signaling and one gene encoding a BMP signaling regulator that is repressed by FGFR2b/1b signaling will be studied. Otic conditional mutants will be generated for each gene, and their morphologic and functional development will be assessed. In addition, the extent to which the BMP regulator contributes to the dnFGFR2b phenotypes and the effects of overexpressing the BMP regulator will be assessed. The results will contribute new knowledge that will facilitate future efforts to manipulate the FGF signaling system for hearing restoration.

内耳上皮的形态发生需要多种信号通路的协调部署 干扰会导致听力和/或平衡异常。随着人工耳蜗植入治疗的出现 即使在内耳畸形的情况下也会导致听力损失，了解这种畸形是如何发生的至关重要 影响听觉神经节和神经支配。此外，鉴于人们对内耳体外生成的强烈关注 用于移植的细胞类型和体内操纵发育信号分子以促进 各种内耳细胞的分化以恢复听力，阐明这些细胞的作用和调节 控制耳分化和形态发生的信号及其效应器对于推进治疗是必要的。 编码 FGF3 和 FGF10 的基因（通过 FGFR2b 和 FGFR1b 发出信号的配体）得到表达 在上皮和神经节区域的整个耳发育过程中动态变化。进行的研究 Mansour 实验室的传统 Fgf3 和 Fgf10 条件敲除小鼠以及表达 a 的小鼠 多西环素诱导配体陷阱 (dnFGFR2b) 可快速抑制通过 FGFR1b 和 FGFR1b 的信号传导 FGFR2b，表明 Fgf3 和 Fgf10 在耳囊形成的基板谱系中不是必需的，但它们是 随后需要耳囊模式形成、神经母细胞维持、上皮增殖以及两者 前庭和耳蜗的形态发生。此外，首次对耳囊 mRNA 进行全基因组分析揭示 FGFR2b/1b 信号传导靶标定义了涉及耳形态发生和功能的新候选基因。 该提案有两个目标，旨在解决以下假设：1) 持续需要 FGFR2b/1b 信令 用于耳神经母细胞的规范和维护，以及后期的间充质信号传导 与上皮和神经节域中的一样，是耳蜗上皮分化和神经节所必需的 2) FGFR2b/1b 下游靶基因介导 FGFR2b/1b 的部分或全部效应 耳形态发生和神经节发生的信号传导。确定 FGFR2b/1b 信号在耳中的早期作用 DOX诱导的神经节形成及其在上皮分化和神经节维持中的后续作用 将采用 dnFGFR2b 的普遍存在和 CRE 限制的表达，以及形态和分子标记 将评估两种组织中耳部模式、增殖和存活的情况。确定角色 FGFR2b/1b 信号传导的下游靶标，两个编码转录因子的基因，由 FGFR2b/1b 信号传导和一个编码受 FGFR2b/1b 抑制的 BMP 信号传导调节因子的基因 将研究信号传输。将为每个基因生成耳条件突变体，以及它们的形态和 将评估功能发展。此外，BMP 调节器对 将评估 dnFGFR2b 表型和过度表达 BMP 调节剂的影响。 结果将贡献新知识，促进未来操纵 FGF 信号传导的努力 听力恢复系统。