INTRAFLAGELLAR TRANSPORT IN CHLAMYDOMONAS REINHARDTII

莱因衣藻的鞭内运输

• 批准号: 6785472
• 负责人: DOUGLAS GENE COLE
• 金额: $ 20.25万
• 依托单位: UNIVERSITY OF IDAHO
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-08-01 至 2006-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6785472
• 关键词: Chlamydomonas; cilium; flagellum; genetic library; intracellular transport; kinesin; molecular assembly /self assembly; mutant; plant genetics; plant proteins; protein protein interaction; protein purification; protein transport; transposon /insertion element

Cilia and flagella are eukaryotic organelles essential for both motility and sensory transduction in animals, animals and protozoa. These organelles share a long rod-shaped microtubular axoneme that projects away from the cell body for long distances ranging from 5 to 100 mum or more. Assembly of these organelles is an engineering problem for the cell, because assembly occurs at the distal end of the organelle, many microns away from the cell body. This problem is solved by a mechanism called Intraflagellar Transport (IFT), which involves the bidirectional movement of molecular rafts along the long axis of these organelles. IFT was first identified in the biflagellate green alga, Chlamydomonas, the model organism for the study of IFT. More recently, IFT has been shown to occur in animals and is now thought to function in most, if not all, ciliated cells. In Chlamydomonas, IFT rafts are ferried upstream to the flagellar tip by FLA10 kinesin-II and downstream to the cell body by cytoplasmic dynein 1B. A primary function of this transport is thought to be delivery of a cargo of axonemal precursors upstream to the site of axonemal assembly. It has also been hypothesized that IFT functions to ferry signals downstream from the tips of cilia and flagella to the cell body, thereby mediating the signal transduction of external stimuli. This transfer of IFT cargo must involve the interaction of IFT raft proteins with flagellar structural proteins. Consistent with this hypothesis, we have found that each of three IFT raft proteins, p57, p88 and p172, contain different repetitive amino acid sequences. Two of these, the coiled-coil motif of p57 and the tetratricopeptide repeat (TPR) of p88 are well known as protein-protein interaction domains. To understand the biological function of these three subunits, we will (1) identify mutants with disruptions of these three IFT genes, and, (2) identify proteins that associate directly with these three IFT raft subunits. These studies will allow us to understand how IFT particles transfer their cargo during the assembly and function of eukaryotic cilia and flagella at the molecular level. The results of these studies may lead to effective treatments for ciliary-dependent diseases, including Kartagener's Syndrome.

纤毛和鞭毛是动物、动物和原生动物的运动和感觉转导所必需的真核细胞器。这些细胞器共享一个长杆状的微管轴突，从细胞体伸出很远的距离，从5到100毫米或更多。这些细胞器的组装是细胞的一个工程问题，因为组装发生在细胞器的远端，离细胞体许多微米远。这个问题是由一种叫做腱束内运输（IFT）的机制解决的，它涉及分子筏沿着这些细胞器的长轴进行双向运动。IFT最早是在双鞭毛类绿藻衣藻中发现的，是研究IFT的模式生物。最近，IFT已被证明在动物身上发生，现在被认为在大多数（如果不是全部的话）纤毛细胞中起作用。在衣藻中，IFT筏通过FLA10动力蛋白ii向上游运送到鞭毛尖端，通过细胞质动力蛋白1B向下游运送到细胞体。这种运输的一个主要功能被认为是将轴突前体的货物运送到轴突组装的上游地点。也有人假设IFT的功能是从纤毛和鞭毛的尖端向下游传递信号到细胞体，从而介导外部刺激的信号转导。这种IFT货物的转移必须涉及IFT筏蛋白与鞭毛结构蛋白的相互作用。与这一假设相一致，我们发现三个IFT筏蛋白p57、p88和p172都含有不同的重复氨基酸序列。其中的两个结构域，p57的卷曲-线圈基序和p88的四肽重复序列（TPR）是众所周知的蛋白质-蛋白质相互作用结构域。为了了解这三个亚基的生物学功能，我们将(1)鉴定这三个IFT基因被破坏的突变体，(2)鉴定与这三个IFT筏亚基直接相关的蛋白质。这些研究将使我们能够在分子水平上了解IFT颗粒在真核纤毛和鞭毛的组装和功能过程中如何转移其货物。这些研究的结果可能导致对包括卡塔格纳综合征在内的纤毛依赖性疾病的有效治疗。