Developmental Mechanisms of Vestibular Maculae Patterning in Mouse

描述（由申请人提供）：听力和平衡感由内耳毛细胞介导，内耳毛细胞是为检测运动而优化的具有专门结构的感觉上皮细胞。毛细胞通过位于顶端细胞表面边缘的纤毛束和立体纤毛束的机械偏转来检测运动。只有束向髂肌束运动才会产生兴奋性反应。因此，纤毛束的适当极化和相邻细胞之间的束极性协调是准确的前庭功能所必需的。Corti器官内的听觉毛细胞以类似的方式探测声音，相邻细胞的束极性也得到协调。这种类型的组织被称为平面细胞极性（PCP），并在许多不同的组织和物种中被描述。此外，前庭黄斑内的毛细胞进一步组织成两组，具有相反的束极性，在极性反转（LPR）的突变线上形成。这增加了可检测的运动范围和灵敏度的运动在一个单一的方向。然而，尽管纤毛束极性和毛细胞模式对前庭功能可能很重要，但尚不清楚纤毛束极化是如何在感觉上皮内启动和协调的。在本研究计划中，将利用转基因、突变和敲除小鼠的组合来评估指导纤毛束极化和毛细胞定向的细胞机制。[关键极性基因van gogh-like2 （vangl2）的功能将通过使用一种新型的vangl2敲除小鼠（vangl2TMS）分析毛细胞PCP来确定。]这些结果将与具有半显性表型特征的内耳PCP突变体分析参考的vangl2突变系环尾进行比较。下一步，我们将通过生产和分析一个Vangl2条件敲除系（vangl2floxedATG）来测试在相邻细胞之间协调细胞束极性的细胞机制，在该敲除系中，极性基因以细胞特异性的方式被删除。这些实验将确定极性信号是否在细胞间传播，以及在内耳形态发生过程中，vangl2对于启动束极性或维持束极性是否必要。此外，其他的vangl2突变会导致胚胎致死，这可以通过产生耳朵特异性的vangl2floxedATG条件敲除来避免。这些小鼠将进行一系列的行为实验，以检查毛细胞定向错误对前庭和听觉功能的影响。

DESCRIPTION (provided by applicant): The senses of hearing and balance are mediated by the hair cells of the inner ear, sensory epithelial cells with specialized architectures optimized for the detection of movement. Hair cells detect motion via the mechanical deflection of a kinocilium and stereocilia bundle located at one edge of the apical cell surface. Only movements of the bundle towards the kinocilium generate an excitatory response. Consequently the proper polarization of the stereocilia bundle and coordination of bundle polarity between adjacent cells is necessary for accurate vestibular function. Auditory hair cells within the organ of Corti detect sound in a similar fashion and the bundle polarity of adjacent cells is also coordinated. This type of organization is called planar cell polarity (PCP) and has been described in a number of different tissues and species. Moreover, hair cells within the vestibular maculae are further organized into two groups with opposite bundle polarities patterned about an abrupt line of polarity reversal (LPR). This increases the range of detectable motion and sensitivity to motion in a single direction. However, despite the likely importance of stereocilia bundle polarity and hair cell patterning for vestibular function it is not known how bundle polarization is initiated and coordinated within the sensory epithelia. Within this research proposal the cellular mechanisms guiding the polarization of the stereocilia bundle and orientation of hair cells will be evaluated using a combination of transgenic, mutant and knockout mice. [The function of the essential polarity gene van gogh-like2 (vangl2) will be determined by analyzing hair cell PCP using a novel vangl2 knockout mouse (vangl2TMS). These results will be compared to the vangl2 mutant line looptail which has become a reference for inner ear PCP mutant analysis despite having semi-dominant phenotypic characteristics.] Next the cellular mechanism of Vangl2 function in coordinating bundle polarity between adjacent cells will be tested through the production and analysis of a vangl2 conditional knockout line (vangl2floxedATG) in which the polarity gene is deleted in a cell-specific manner. These experiments will determine whether polarity cues are propagated from cell to cell and whether vangl2 is necessary for initiating bundle polarity or maintaining bundle polarity during inner ear morphogenesis. In addition, other vangl2 mutations result in embryonic lethality and this will be avoided be generating ear-specific vangl2floxedATG conditional knockouts. These mice will enable a series of behavioral experiments to examine the effects of hair cell misorientation on vestibular and auditory function. PUBLIC HEALTH RELEVANCE: Project Narrative The proper morphogenesis and organization of specialized inner ear sensory receptors called hair cells is necessary for hearing and balance, and the loss of these cells is the primary basis of age-related deafness and balance disorders. This project is designed to determine how hair cells are oriented and patterned within the within the vestibular maculae of the utricle and saccule. Understanding these events should reveal the basis of some forms of vestibular dysfunction and will define critical parameters that must be met by therapeutic approaches that rely upon introducing replacement hair cells into the mature inner ear.