Calcium regulation of flagellar motility

描述(申请人提供)：本项目的目标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，活动的纤毛/鞭毛是精子推进、呼吸道碎片清除、脑脊液循环所必需的，甚至是在发育过程中确定左右身体平面所必需的。因此，运动障碍可能会导致生育能力受损、呼吸窘迫、脑积水和/或左右体轴的随机化。组成这些细胞器的结构和分子非常保守。因此，从任何单细胞类型的研究中获得的运动性基本原理通常适用于所有真核生物的纤毛和鞭毛。了解动力蛋白如何被调节以产生纤毛/鞭毛跳动的典型复杂波形，仍然是纤毛运动领域最紧迫的悬而未决的问题。大量数据有助于建立一个模型，在该模型中，轴丝微管作为组装分子的支架，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通路，以改变细胞外信号的搏动。钙调素(CaM)是一种关键的钙感受器，高度保守的CaM结合蛋白定位于已知在运动中起作用的轴丝结构，这一发现为这项工作奠定了基础。拟议的实验旨在检验这样一种假设，即特定的CaM结合蛋白是信号转导网络的一部分，该网络改变了对钙的反应的运动性。这一建议的具体目的是：1)培养在CaM相互作用中存在缺陷的菌株；2)检验与CaM相关的中央装置在调节特定双线微管上的动力蛋白活性方面的作用的假说；3)检验轮辐相关的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说。这些研究有可能确定CaM介导的信号转导的分子机制，包括特定的蛋白质-蛋白质相互作用作为开关来控制动力蛋白的活性，以及更广泛的潜力来定义分子的靶向和锚定的新原则，这些分子定义了调节动力蛋白马达家族的信号转导途径。 与公共健康相关：我们对确定钙调节纤毛和鞭毛运动的机制感兴趣。在哺乳动物中，活动的纤毛/鞭毛是精子推进、呼吸道碎片清除、脑脊液循环所必需的，甚至是在发育过程中确定左右身体平面所必需的(Satir和Christensen，2006)。因此，运动障碍可能导致生育力受损、呼吸窘迫、脑积水和/或左右体轴随机化(Badano等人，2006年)。

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).