Sensory cell fate specification in the inner ear

内耳感觉细胞命运规范

• 批准号: 7888222
• 负责人: DOUGLAS J EPSTEIN
• 金额: $ 32.6万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-08-01 至 2013-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7888222
• 关键词: Accounting; Address; Alleles; Auditory; Cells; Cochlea; Cochlear duct; Crista ampullaris; Defect; Dependency; Development; Differentiation and Growth; Dorsal; Ear; Embryo; Epithelial; Epithelium; Equilibrium; Erinaceidae; Gene Targeting; Genetic; Genetic Recombination; Hair Cells; Hearing; Human; Inherited; Labyrinth; Ligands; Mammals; Medial; Mediating; Mediator of activation protein; Molecular; Morphogenesis; Movement; Mus; Organ; Organ of Corti; Otic Vesicle; Pathogenesis; Pathway interactions; Pattern; Phenotype; Population; Role; Semicircular canal structure; Sensory; Signal Pathway; Signal Transduction; Signaling Molecule; Staging; Structure; Supporting Cell; System; Tamoxifen; Testing; Time; Transcriptional Regulation; Transducers; Vestibular Diseases; Work; base; body system; cell fate specification; cell growth; cell type; deafness; extracellular; hindbrain; human SMO protein; improved; macula; mutant; notochord; otoconia; progenitor; promoter; public health relevance; recombinase; research study; smoothened signaling pathway; sound

DESCRIPTION: Extracellular signaling molecules provide the vertebrate inner ear with positional information at multiple stages of its development to produce the required patterns of growth and differentiation necessary for the formation of the vestibulum and cochlea, the two inner ear organs responsible for sensing, balance and sound, respectively. In previous work, we identified roles for the secreted factors, Shh and Wnt1/Wnt3a, in the polarization of the mouse otic vesicle along its dorsal-ventral axis. Our studies determined that Shh, secreted from the notochord, signals directly to ventral regions of the otic epithelium to direct the outgrowth of the cochlear duct. Whereas, Wnt1/Wnt3a, secreted from the dorsal hindbrain, signals to the dorsal otocyst to regulate vestibular morphogenesis. In addition to these early roles, Hedgehog (Hh) and Wnt/2catenin signaling pathways are also active at critical junctures later in ear development when sensory epithelial progenitors are undergoing their specification and differentiation into hair cells and support cells. We now propose to investigate the specific requirements of Wnt/2catenin and Hh signaling pathways at later stages of inner ear development in the mouse, using a conditional gene targeting strategy that inactivates essential mediators of these pathways at defined periods of cochlear and vestibular development. Our conditional gene targeting approach takes advantage of our recent finding that Wnt responsive cells originating in the dorsal otocyst extend ventrally over time and contribute to the sensory epithelium of the cochlear duct. Using a tamoxifen inducible form of cre recombinase, expressed under the transcriptional control of a Wnt responsive Top promotor (TopcreER), floxed alleles of 2catenin and Smoothened will be inactivated in sensory epithelial progenitors. Preliminary results indicate that Wnt/2catenin signaling is required for the specification and/or differentiation of hair cells and support cells in the organ of corti and cristae of the semicircular canals. Experiments in this proposal will further elaborate on the mechanisms by which Wnt/2catenin and Hh signaling pathways function to mediate sensory cell fates in the inner ear. We have also developed a genetic recombination based strategy to indelibly mark Wnt responsive cells in the dorsal otocyst in order to trace their fates over the course of inner ear development. Additional experiments described in this proposal will test the hypothesis that hair cells and support cells in the organ of corti derive from a population of Wnt responsive progenitors in the dorsal otocyst. Results from these studies should improve our fundamental understanding of sensory development in auditory and vestibular regions of the inner ear. PUBLIC HEALTH RELEVANCE The auditory and vestibular structures of the inner ear mediate our senses of hearing and balance, respectively. Progress continues to be made in identifying the causes of hereditary forms of deafness and vestibular disease in humans. Nonetheless, a detailed understanding of the genetic pathways coordinating inner ear development remains limited. By elucidating the genetic networks regulating cell fate decisions in the inner ear, our studies should not only improve our fundamental understanding of this intricate organ, but also the pathogenesis of congenital forms of deafness.

描述：细胞外信号分子在其发育的多个阶段提供脊椎动物内耳的位置信息，以产生所需的生长和分化模式，以形成前庭和耳蜗，这是两个负责感应，平衡和声音的内耳器官。在先前的工作中，我们确定了分泌因子SHH和WNT1/WNT3A的作用，在小鼠耳囊沿其背腹侧轴极化中。我们的研究确定，从脊索分泌的SHH可以直接向眼皮上皮的腹侧区域发出信号，以指导人工耳蜗的生长。而Wnt1/wnt3a从背后后部分泌的，是指向背耳囊的信号，以调节前庭形态发生。除了这些早期作用外，当感觉上皮祖细胞经过规格并分化为毛细胞和支持细胞时，刺猬（HH）和WNT/2CATENIN信号通路在稍后的临界关时也处于活动状态。现在，我们建议使用条件基因靶向策略来研究小鼠内耳发育后的后期Wnt/2Catenin和HH信号通路的特定要求，该策略使这些途径的基本介体在人工耳蜗和前庭发育的定义时期灭活。我们的条件基因靶向方法利用了我们最近的发现，即Wnt响应性细胞源自背耳细胞，随着时间的流逝，腹侧延伸，并有助于耳蜗管的感觉上皮。使用他莫昔芬的诱导形式的Cre重组酶，在Wnt响应式顶部启动子（TopCreer）的转录控制下表达，2蛋白酶的flox等位基因和平滑的等位基因将在感觉上皮祖细胞中失活。初步结果表明，毛细胞的规范和/或分化了半圆形管的皮尔蒂和克里斯塔的器官中的毛细胞的规范和/或支撑细胞所必需的。该提案中的实验将进一步详细介绍Wnt/2Catenin和HH信号通路的机制，以介导内耳中的感觉细胞命运。我们还制定了一种基于遗传重组的策略，以不可磨灭地标记背侧耳囊中的Wnt反应性细胞，以便在内耳发育过程中追踪其命运。该提案中描述的其他实验将检验以下假设：毛细胞和支持细胞的Corti器官中源自背侧耳囊中的Wnt响应性祖细胞的种群。这些研究的结果应提高我们对内耳听觉和前庭区域感觉发展的基本理解。公共卫生相关性的内耳的听觉和前庭结构分别调解了我们的听力和平衡感。在确定人类遗传形式的遗传形式和前庭疾病的原因方面，继续取得了进步。但是，对协调内耳发育的遗传途径的详细理解仍然有限。通过阐明调节内耳细胞命运决策的遗传网络，我们的研究不仅应提高我们对这种复杂器官的基本理解，而且还应提高对耳聋的先天性形式的发病机理。