Calcium regulation of flagellar motility

钙对鞭毛运动的调节

• 批准号: 6932487
• 负责人: Elizabeth F Smith
• 金额: $ 27.65万
• 依托单位: DARTMOUTH COLLEGE
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-08-01 至 2008-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6932487
• 关键词: Chlamydomonas; biological signal transduction; calcium binding protein; calcium flux; calmodulin; calmodulin dependent protein kinase; cell component structure /function; centrosome; cilium /flagellum motility; dynein ATPase; flagellum; microtubules; protein localization; tissue /cell culture

DESCRIPTION (provided by applicant): The long-range goal of this project is to determine the mechanism by which the molecular motor dynein is regulated to produce the complex waveforms characteristic of beating eukaryotic cilia and flagella. The proposed research is specifically aimed at understanding how changes in calcium modulate the size and shape of ciliary and flagellar bends to control motility. Several studies have indicated that the flagellar central apparatus is a key component of a signal transduction pathway that regulates dynein activity to modulate waveform. The objectives of this proposal are founded on the hypothesis that the central apparatus locally controls a calcium sensor to regulate dynein activity, and that calmodulin and an axonemal calmodulin dependent kinase mediate the calcium signal. The proposed experiments are designed to test this hypothesis and to identify axoneme components involved in the calmodulin-mediated signal transduction pathway. The Specific Aims are: 1) to identify calmodulin-binding proteins associated with the central apparatus; 2) to characterize calmodulin dependent kinases associated with the axoneme; and 3) to determine if the activities of particular dynein subforms attached to specific subsets of doublet microtubules are preferentially modulated by changes in calcium. The unicellular green alga, Chlamydomonas reinhardtii, is the organism of choice for these studies as it is the only system that offers motility mutants, virtually unlimited material for biochemical approaches, and unique in vitro functional assays. Many of the genes encoding flagellar proteins in Chlamydomonas show high sequence similarity with genes in the human genome and EST databases. Therefore, the information obtained in Chlamydomonas will be directly applicable to higher eukaryotes and may provide insight into defects that result in primary cilia dyskinesia including Kartegener's syndrome. Studies of dynein regulation and control of flagellar waveform will also impact upon our understanding of certain developmental processes. For example, the nodal cilia in developing embryos have been implicated in the production of a morphogen gradient responsible for generating left-right asymmetry. This result explains the observation that about 50% of patients with immotile-cilia syndrome also have situs inversus. Interestingly, nodal cilia utilized during development do not assemble a central apparatus and beat with a different waveform than cilia of epithelial cells found in the same organism. This observation further illustrates the importance of controlling ciliary and flagellar waveforms appropriate for particular cell types.

描述（由申请人提供）：该项目的长期目标是确定分子运动动力蛋白被调节以产生跳动真核纤毛和鞭毛的复杂波形特征的机制。拟议的研究专门旨在了解钙的变化如何调节纤毛和鞭毛弯曲的大小和形状以控制运动。多项研究表明，鞭毛中央装置是调节动力蛋白活性以调节波形的信号转导途径的关键组成部分。该提案的目标基于以下假设：中央装置局部控制钙传感器来调节动力蛋白活性，并且钙调蛋白和轴丝钙调蛋白依赖性激酶介导钙信号。所提出的实验旨在检验这一假设并鉴定参与钙调蛋白介导的信号转导途径的轴丝成分。这 具体目标是：1）鉴定与中枢装置相关的钙调蛋白结合蛋白； 2) 表征与轴丝相关的钙调蛋白依赖性激酶； 3) 确定附着在双联微管特定亚型上的特定动力蛋白亚型的活性是否优先受钙变化的调节。单细胞绿藻莱茵衣藻是这些研究的首选生物体，因为它是唯一提供运动突变体、几乎无限的生化方法材料和独特的体外功能测定的系统。 衣藻中许多编码鞭毛蛋白的基因与人类基因组和 EST 数据库中的基因显示出高度的序列相似性。因此，在衣藻中获得的信息将直接适用于高等真核生物，并可能提供对导致原发性纤毛运动障碍（包括卡特格纳综合征）的缺陷的深入了解。对动力蛋白调节和鞭毛波形控制的研究也将影响我们对某些发育过程的理解。例如，发育胚胎中的结纤毛与形态发生素梯度的产生有关，该梯度负责产生左右不对称。这一结果解释了大约 50% 纤毛不动综合征患者也患有内位反位的观察结果。有趣的是，发育过程中使用的节点纤毛不会组装中央装置，并且以与同一生物体中发现的上皮细胞纤毛不同的波形跳动。这一观察结果进一步说明了控制适合特定细胞类型的纤毛和鞭毛波形的重要性。