Molecular embryology of the mammalian inner ear

项目总结/摘要 我们实验室的长期目标是确定基于基因和细胞的策略， 功能失调的内耳的平衡。 短期目标是促进我们对 小鼠内耳的形态发生、模式形成和细胞命运特化。我们用鼠标作为 模型系统，因为存在一系列不断扩大的自然和诱导基因突变， 人类内耳功能障碍的准确范例。 我们的总体技术方法依赖于 实验胚胎学，一系列手术，成像，显微注射和分子技术， 进入子宫内发育中的小鼠内耳，并对前体细胞进行遗传操作， 上升到听觉和前庭感觉结构。本研究的主要目的是：1）对小鼠耳源性耳聋进行命运定位， 2）确定耳前体细胞做出的细胞命运选择的类型和这些选择的时机。 和3）确定神经上皮祖细胞对分化的内耳的克隆贡献。命运地图 描述了内耳成熟时细胞的不同群体。 发育生物学家利用 命运图，以了解祖基因表达在发育中的组织或器官如何驱动成熟， 结果是获得了形式和功能。不可消除标记的前体与已知结构域的交叉 基因表达的变化可以教会我们感知器官和指定细胞命运所需的分子信号。 另一方面，谱系分析鉴定了单个耳前体产生的分化细胞， 揭示了它们在成熟感觉器官中的位置。克隆关系告诉我们，如果基因定义的池 的前体在发育的早期就被编程，以产生内部的大体解剖结构。 耳朵和感觉贴片。命运映射和谱系分析的结果是对 祖细胞身份和行为的遗传调节。 而这一监管承诺将远远超过 这是最初设想的复杂。最近的遗传命运图谱数据显示，神经上皮祖细胞 来自神经管和可能的神经嵴的前体细胞向耳上皮细胞贡献， 感觉细胞和非感觉细胞分化。这些新的数据坚定地挑战了这样一个观念，即内部 耳完全从基板外胚层发育，这意味着神经外胚层可能独特地参与 图案化和细胞命运规范。这些遗传上可分离的神经上皮前体的克隆分析 种群将推进我们关于小鼠内耳胚胎起源的核心知识。 一个更 对内耳祖细胞的命运、谱系和行为的完全理解将为内耳祖细胞的设计提供信息。 以基因和细胞为基础的策略，旨在恢复听力和平衡。

Project Summary/Abstract The long term goal of our laboratory is to define gene- and cell-based strategies that restore hearing and balance in the dysfunctional inner ear. The short term goals are to advance our understanding of morphogenesis, pattern formation, and cell fate specification in the mouse inner ear. We use the mouse as a model system because an ever-expanding array of natural and induced genetic mutations exist that serve as accurate paradigms for human inner ear dysfunction. Our overarching technical approach relies on experimental embryology, a palette of surgical, imaging, microinjection and molecular techniques that permit access to the developing mouse inner ear in utero and enable genetic manipulation of precursor cells that give rise to the auditory and vestibular sensory structures. In this proposal, we aim: 1) to fate map the mouse otic vesicle in vivo~ 2) to define the types of cell fate choices otic precursors make and the timing of those choices~ and 3) to define the clonal contributions of neuroepithelial progenitors to the differentiated inner ear. A fate map describes what distinct populations of cells become as the inner ear matures. Developmental biologists use fate maps to understand how progenitor gene expression in a developing tissue or organ drives maturation and results in the acquisition of form and function. Intersection of indelibly labeled precursors with known domains of gene expression can teach us the molecular signals required to pattern sensory organs and specify cell fate. Lineage analysis, on the other hand, identifies the differentiated cells an individual otic precursor makes and reveals their location in the mature sensory organ. Clonal relationships will teach us if genetically defined pools of precursors are programmed early on in development to give rise to gross anatomical structures in the inner ear and to the sensory patches. The output of fate mapping and lineage analysis is a deeper understanding of the genetic regulation of progenitor cell identity and behavior. And that regulation promises to be far more complex that originally envisioned. Recent genetic fate mapping data show that neuroepithelial progenitor cells from the neural tube and likely the neural crest contribute precursor cells to the otic epithelium that generate sensory and nonsensory cells upon differentiation. These novel data firmly challenge the precept that the inner ear develops exclusively from placodal ectoderm and imply that neural ectoderm may uniquely participate in patterning and cell fate specification. Clonal analysis of these genetically separable neuroepithelial precursor populations will advance our core knowledge about the embryonic origins of the mouse inner ear. A more complete understanding of the fate, lineage, and behavior of inner ear progenitor cells will inform the design of gene- and cell-based strategies aimed at the restoration of hearing and balance.