Fluid transport in inner ear development

内耳发育中的液体运输

• 批准号: 8297895
• 负责人: A. Philine Wangemann
• 金额: $ 37.74万
• 依托单位: KANSAS STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-01 至 2017-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8297895
• 关键词: Address; Affect; Age; Auditory; Bicarbonates; Birth; Brain Stem; Carbon Dioxide; Child; Childhood; Cochlea; Code; Development; Embryo; Embryonic Development; Endolymph; Epithelial Cells; Epithelium; Equilibrium; Etiology; Fluids and Secretions; Fossils; Gene Mutation; Genes; Genetic; Goals; Hearing; Hearing Impaired Persons; Histology; Homeostasis; Human; Impairment; In Situ Hybridization; Incidence; Individual; Inherited; Ion Transport; Ion-Selective Electrodes; Labyrinth; Language Development; Liquid substance; Location; Measurement; Measures; Mediating; Modeling; Monitor; Mus; Mutant Strains Mice; Mutation; Orthologous Gene; Patients; Phenotype; Population; Prevention; Proteins; Role; Speech; Testing; Time; Ursidae Family; Vestibular Aqueduct; Vestibular Labyrinth; absorption; apical membrane; base; deafness; endolymphatic sac; hearing impairment; immunocytochemistry; membranous labyrinth; mouse model; novel; postnatal; prevent; restoration; therapy development; treatment strategy

DESCRIPTION (provided by applicant): About 1 in 1000 children has hereditary hearing loss with mutations of SLC26A4 being one of the most prevalent known causes of hereditary deafness. The high incidence provides an imperative to investigate the etiology of SLC26A4-related deafness with the ultimate goal to develop strategies to restore and preserve hearing in afflicted individuals. The human gene SLC26A4 and the mouse ortholog Slc26a4 code for pendrin. Studies in mouse have demonstrated that pendrin is a Cl-/HCO3- exchanger in the cochlea, vestibular labyrinth and the endolymphatic sac. Lack of pendrin during embryonic development causes an acidification of endolymph and a mismatch between fluid secretion in the vestibular labyrinth and pendrin-dependent fluid absorption in the endolymphatic sac that leads to an enlargement of the membranous labyrinth and an impairment of cochlear development. The enlarged vestibular aqueduct, frequently associated with mutations of SLC26A4, appears to be a fossil-like record of such an enlargement that was present during embryonic development. Mechanisms of fluid secretion and fluid absorption in the embryonic inner ear are virtually unknown. Filling this gap in our understanding of inner ear development is critical toward the development of treatments to protect hearing in individuals afflicted with mutations of SLC26A4. We have developed four Specific Aims that address the most salient questions in mouse models: Aim1) - what is the ionic composition of endolymph in the embryonic cochlea and the endolymphatic sac? This aim will be addressed by measuring the composition of inner ear fluids with ion-selective electrodes. Aim2) what mechanisms mediate fluid secretion? Aim3) what mechanisms mediate fluid absorption? These aims will be addressed by testing hypothetical models of fluid secretion and fluid absorption. The onset and location of expression of candidate channels and transporters will be determined by qRT-PCR and immunocytochemistry or in-situ hybridization. Selected models will be tested in compound-mutant mice. Deficient expression of channels or transporters implicated in fluid secretion is expected to curb cochlear enlargement and possibly restore normal cochlear development in the absence of pendrin. Conversely, deficient expression of channels or transporters implicated in fluid absorption is expected to cause cochlear enlargement in the presence of pendrin. Aim4) is restoration of pendrin expression solely to the endolymphatic sac sufficient to prevent cochlear enlargement and deafness? This aim will be addressed by generating mice with pendrin expression limited to the endolymphatic sac of the inner ear. Studies will include monitoring cochlear lumen formation by histology, measurements of the endocochlear potential and endolymphatic pH with ion-selective electrodes and evaluating hearing by auditory brain stem recordings. Completion of these four Aims will establish an understanding of fluid homeostasis in cochlear development which holds the promise to reveal treatment strategies that are suitable to prevent deafness in individuals that bear mutations of SLC26A4. PUBLIC HEALTH RELEVANCE: Mutations of the gene SLC26A4 are one of the most important causes of hearing loss in young children and this high incidence provides an imperative to investigate the etiology of SLC26A4-related deafness with the ultimate goal to develop strategies to restore and preserve hearing in afflicted individuals. The human gene SLC26A4 and the mouse ortholog Slc26a4 code for the protein pendrin that contributes to fluid transport in the embryonic inner ear in a way that is critical for the development of hearing. This proposal uses mouse models to address fundamental questions regarding fluid transport in the embryonic inner ear, which is critical for the development of treatments that protect hearing in individuals afflicted with mutations of SLC26A4.

描述（由申请人提供）：大约有1000名儿童患有遗传性听力损失，而SLC26A4的突变是最普遍的遗传性耳聋原因之一。高发率提供了研究与SLC26A4相关的耳聋的病因，并最终目标是制定恢复患者的恢复和保留听力的策略。人类基因SLC26A4和Pendrin的小鼠直系同源物SLC26A4代码。在小鼠中的研究表明，pendrin是耳蜗，前庭迷宫和内淋巴囊中的Cl-/hco3-交换器。胚胎发育过程中缺乏板蛋白会导致内淋巴的酸化和前庭迷宫中的液体分泌与内淋巴囊中的pendrin依赖性液体吸收之间的不匹配，从而导致膜的迷宫和同志发育障碍。通常与SLC26A4突变相关的前庭渡槽似乎是化石样的记录，记录了胚胎发育过程中存在的这种增大。胚胎内耳中液体分泌和液体吸收的机制几乎未知。在我们对内耳发展的理解中填补这一空白对于保护患有SLC26A4突变的个体的听力的治疗过程至关重要。我们已经开发了四个特定的目标，可以解决小鼠模型中最突出的问题：AIM1） - 胚胎耳蜗和内淋巴囊中内淋巴的离子组成是什么？通过测量内耳流体与离子选择电极的组成来解决此目标。 AIM2）哪些机制介导流体分泌？ AIM3）哪些机制介导了液体吸收？这些目标将通过测试流体分泌和吸收流体吸收的假设模型来解决。候选通道和转运蛋白表达的发作和位置将由QRT-PCR和免疫细胞化学或原位杂交确定。选定的模型将在化合物突变小鼠中进行测试。与液体分泌有关的通道或转运蛋白的不足有望在没有pendrin的情况下遏制人工耳蜗增大，并可能恢复正常的耳蜗发育。相反，与液体吸收有关的通道或转运蛋白的表达不足有望在Pendrin存在下引起人工耳蜗增大。 AIM4）pendrin表达的恢复仅仅是对足以防止人工耳蜗增大和耳聋的内晶囊的恢复？通过将Pendrin表达的小鼠限于内耳的内淋巴结囊，将解决此目标。研究将包括通过组织学监测人工耳腔形成，通过离子选择电极的内凝切潜力和内淋巴pH的测量，并通过听觉脑干记录评估听力。这四个目标的完成将在人工耳蜗开发中对流体稳态建立理解，这有望揭示适合防止SLC26A4突变的个体耳聋的治疗策略。 公共卫生相关性：基因SLC26A4的突变是幼儿听力丧失的最重要原因之一，这种高发病率提供了调查SLC26A4相关的聋哑人的病因，并具有制定恢复和保留听力听力的策略的最终目标在受苦的个人中。人类基因SLC26A4和小鼠直系同源物slc26a4代码蛋白质板蛋白代码，以对听力发展至关重要的方式有助于胚胎内耳中的流体转运。这 提案使用小鼠模型来解决有关胚胎内耳中流体转运的基本问题，这对于保护患有SLC26A4突变的个体听力的治疗至关重要。