Calcium regulation of flagellar motility

描述（由申请人提供）：本项目目的是了解钙改变纤毛和鞭毛弯曲的大小和形状以控制运动的机制。在哺乳动物中，运动的纤毛/鞭毛是精子推进、清除呼吸道碎片、脑脊液循环，甚至是发育过程中确定左右身体计划所必需的。因此，运动缺陷可能导致生育能力受损、呼吸窘迫、脑积水和/或左右体轴随机化。构成这些细胞器的结构和分子是非常保守的。因此，从任何单一细胞类型的研究中获得的运动的基本原理一般适用于所有真核纤毛和鞭毛。了解动力蛋白是如何调节产生搏动纤毛/鞭毛的复杂波形的，仍然是纤毛运动领域最紧迫的未解之谜。大量数据有助于建立一个模型，其中轴突微管作为分子组装的支架，形成最终调节动力蛋白的信号转导途径。第二信使钙影响这些信号转导途径，以响应细胞外信号改变跳动。钙调素（CaM）是一种关键的钙传感器，并且高度保守的CaM结合蛋白定位于已知在运动中起作用的轴突结构，这一发现为这项工作奠定了基础。提出的实验旨在验证特定的cam结合蛋白是信号转导网络的一部分，该网络改变了钙响应的运动性。本提案的具体目标是：1)开发具有CaM相互作用体缺陷的菌株；2)验证中枢装置相关CaM在调节特定双态微管上动力蛋白活性中起作用的假设；3)验证轮辐相关的CaM结合复合体（CSC）是调节动力蛋白活性的信号转导途径的结构和功能成分的假设。这些研究有可能定义CaM介导的信号转导的分子机制，包括作为控制动力蛋白活性开关的特定蛋白质-蛋白质相互作用，以及更广泛的潜力，为定义调节马达动力蛋白家族的信号转导途径的分子的靶向和锚定定义新的原则。

DESCRIPTION (provided by applicant): The goal of this project is to understand the mechanism by which calcium alters the size and shape of ciliary and flagellar bends to control motility. In mammals, motile cilia / flagella are required for sperm propulsion, removal of debris from the respiratory tract, circulation of cerebrospinal fluid, and even for determination of the left-right body plan during development. As a consequence, defects in motility may result in impaired fertility, respiratory distress, hydrocephalus, and/or randomization of the left-right body axis. The architecture and molecules which comprise these organelles are remarkably conserved. Therefore, fundamental principles for motility obtained from studies of any single cell type are generally applicable to all eukaryotic cilia and flagella. Understanding how dynein is regulated to produce the complex waveforms typical of beating cilia / flagella is still the most pressing unanswered question in the field of ciliary motility. Substantial data has contributed to a model in which the axonemal microtubules act as a scaffold for the assembly of molecules that form a signal transduction pathway that ultimately regulates dynein. The second messenger calcium impacts upon these signal transduction pathways to alter beating in response to extracellular cues. The discovery that calmodulin (CaM) is a key calcium sensor and that highly conserved CaM-binding proteins are localized to axonemal structures known to play a role in motility form the foundation for this work. The proposed experiments are designed to test the hypothesis that specific CaM-binding proteins are part of a signal transduction network that alters motility in response to calcium. The Specific Aims of this proposal are to 1) develop strains with defects in CaM interactors; 2) test the hypothesis that central apparatus associated CaM plays a role in modulating dynein activity on specific doublet microtubules; and 3) test the hypothesis that a spoke-associated CaM binding complex, the CSC, is both a structural and functional component of a signal transduction pathway that modulates dynein activity. These studies have the potential to define a molecular mechanism for CaM mediated signal transduction that includes specific protein-protein interactions acting as switches to control dynein activity, as well as the broader potential to define new principles for the targeting and anchoring of molecules that define signal transduction pathways that regulate the dynein family of motors. PUBLIC HEALTH RELEVANCE: We are interested in defining mechanisms for calcium regulation of ciliary and flagellar motility. In mammals, motile cilia / flagella are required for sperm propulsion, removal of debris from the respiratory tract, circulation of cerebrospinal fluid, and even for determination of the left-right body plan during development (reviewed in Satir and Christensen, 2006). As a consequence, defects in motility may result in impaired fertility, respiratory distress, hydrocephalus, and/or randomization of the left-right body axis (reviewed in Badano et al, 2006).