Mechanism and Functional Significance of Polarity Reversal in Mechanosensory Organs

机械感觉器官极性反转的机制和功能意义

• 批准号: 10305653
• 负责人: Kathleen E Cullen
• 金额: $ 69.94万
• 依托单位: JACKSON LABORATORY
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-12-01 至 2024-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10305653
• 关键词: Ablation; Acceleration; Address; Adopted; Adult; Affect; Age; Anatomy; Animal Model; Anterior; Auditory; Automobile Driving; Behavior; Birth; Calcium; Cell Differentiation process; Cell Maturation; Cell Polarity; Cell physiology; Cells; Cessation of life; Complex; Data; Development; Disease; Dizziness; Electrophysiology (science); Ensure; Epithelial; Epithelial Cells; Equilibrium; Evoked Potentials; Eye Movements; Fishes; Frequencies; Functional disorder; G-Protein-Coupled Receptors; G-substrate; GTP-Binding Proteins; Genetic; Genetic Epistasis; Goals; Gravity Perception; Hair; Hair Cells; Head; Head Movements; Hearing; Heterotrimeric GTP-Binding Proteins; Homologous Gene; Image; Impairment; Intercellular Junctions; Ion Channel; Labyrinth; Lateral; Measures; Mediating; Modality; Molecular; Motion; Mus; Mutant Strains Mice; Organ; Orphan; Pathway interactions; Pattern; Pertussis Toxin; Phenocopy; Physiology; Population; Positioning Attribute; Process; Proteins; Research; Role; Saccule and Utricle; Saccule structure; Sense Organs; Sensory; Shapes; Signal Transduction; Sister; Stimulus; System; Testing; Time; Utricle structure; Vertebrates; Vision; Visual; Water Movements; Work; Zebrafish; afferent nerve; base; behavior test; emx2 protein; gamma-Aminobutyric Acid; gaze; innovation; insight; interest; kinetosome; lateral line; macula; mechanical stimulus; mechanotransduction; molecular marker; mutant; nerve supply; neuromast; planar cell polarity; prevent; programs; public health relevance; receptor; receptor function; regional difference; response; signal processing; therapy design; transcription factor; vestibulo-ocular reflex; virtual; water flow

PROJECT SUMMARY/ABSTRACT Vestibular disorders affect as many as 35% of adults past age 40. Studies of the vestibular inner ear have yielded important insights into how we process and compensate for head motion including the existence of parallel channels of information in the afferent nerve. In macular organs, for example, two populations of hair cells adopt opposite planar orientations of their hair bundles and thus opposite responses to head movements. This highly conserved bidirectional organization was first described in neuromasts, the lateral line organs sensing water movements in fish, but the genetic program implementing this reversal during development is only starting to be deciphered. Consequently, ablation studies to reveal the importance of reversal for vestibular function have not been possible until recently. Here we propose to address this question by investigating the consequences of inactivating an orphan G protein coupled receptor (GPCRx), implicated by our preliminary data in orientation reversal in mouse hair cell epithelia. Based on our preliminary data, we suggest that mouse GPCRx functions downstream of the transcription factor EMX2 and upstream of the heterotrimeric G protein Gi to reverse a ground state of polarity established by planar cell polarity proteins. We will test this hypothesis and also use the GPCRx mutant as an animal model to pinpoint how polarity reversal shapes macular organ responses and downstream effects on vestibular behaviors. To reach these goals, we will: 1) Use genetics to determine how GPCRx instructs reversal at the molecular level, solving its epistatic relationship to EMX2, Gi and planar cell polarity proteins in mice, and use zebrafish to test whether GPCRx-Gi is a conserved effector pathway for reversal. 2) Use molecular markers, electrophysiology and calcium imaging to resolve hair cell maturation and function in absence of polarity reversal. 3) Determine how polarity reversal affects afferents' organization and function, with afferent recordings, as well as overall vestibular function using behavioral tests. Our coherent body of preliminary evidence ensures the feasibility and the high interest of the project, and our focus on a virtually unstudied receptor protein guarantees innovation. The multi-PI team is ideally suited to address complementary questions in both the mouse and zebrafish acoustico-lateralis systems. We anticipate that this collaborative effort will be decisive towards solving the mechanism of hair cell orientation reversal, its conservation across vertebrates and its significance for mammalian vestibular physiology. Thorough understanding of polarity reversal will help interpret and design treatments for vestibular dysfunctions.

项目概要/摘要 前庭疾病影响多达 35% 的 40 岁以上成年人。对前庭内耳的研究表明 对我们如何处理和补偿头部运动（包括头部运动的存在）产生了重要的见解 传入神经中的平行信息通道。例如，在黄斑器官中，有两种毛发 细胞采用相反的发束平面方向，因此对头部运动做出相反的反应。 这种高度保守的双向组织首先在神经丘（侧线器官）中被描述 感知鱼类的水运动，但在发育过程中实现这种逆转的遗传程序是 才刚刚开始被破译。因此，消融研究揭示了逆转的重要性 直到最近，前庭功能才成为可能。在这里我们建议通过以下方式解决这个问题 研究失活孤儿 G 蛋白偶联受体 (GPCRx) 的后果，涉及 我们在小鼠毛细胞上皮细胞方向反转方面的初步数据。根据我们的初步数据，我们 表明小鼠 GPCRx 在转录因子 EMX2 下游和转录因子 EMX2 上游发挥作用。 异三聚体 G 蛋白 Gi 可逆转平面细胞极性蛋白建立的极性基态。 我们将测试这一假设，并使用 GPCRx 突变体作为动物模型来查明极性如何 逆转塑造黄斑器官反应和对前庭行为的下游影响。为了达到这些 为了实现目标，我们将： 1) 使用遗传学来确定 GPCRx 如何在分子水平上指示逆转，解决其问题 与小鼠 EMX2、Gi 和平面细胞极性蛋白的上位关系，并使用斑马鱼测试是否 GPCRx-Gi 是一种保守的逆转效应途径。 2) 使用分子标记、电生理学和 钙成像可在极性反转的情况下解决毛细胞的成熟和功能问题。 3）确定如何 极性反转影响传入的组织和功能，传入记录以及整体 使用行为测试来评估前庭功能。我们连贯的初步证据确保了可行性 以及对该项目的高度兴趣，以及我们对几乎未经研究的受体蛋白的关注保证 创新。多 PI 团队非常适合解决鼠标和 斑马鱼的声外侧系统。我们预计这种合作努力将对 解决毛细胞方向反转的机制、其在脊椎动物中的保守性及其意义 用于哺乳动物前庭生理学。透彻理解极性反转将有助于解释和设计 前庭功能障碍的治疗。