INTRAFLAGELLAR TRANSPORT IN CHLAMYDOMONAS REINHARDTII

莱因衣藻的鞭内运输

• 批准号: 7179616
• 负责人: DOUGLAS GENE COLE
• 金额: $ 7.51万
• 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/7179616
• 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.

纤毛和鞭毛是真核生物的细胞器，对动物、动物和原生动物的运动和感觉转导都是必不可少的。这些细胞器共享一个长的杆状微管轴丝，从细胞体伸出5到100微米或更远的距离。这些细胞器的组装对于细胞来说是一个工程问题，因为组装发生在细胞器的远端，距离细胞体许多微米。这个问题通过一种称为鞭毛内运输(IFT)的机制来解决，该机制涉及分子筏沿着这些细胞器的长轴双向移动。IFT最早是在研究IFT的模式生物--衣藻中发现的。最近，IFT被证明发生在动物身上，现在被认为是大多数纤毛细胞的功能，如果不是全部的话。在衣藻中，IFT筏通过FLA10激动素-II向上输送到鞭毛顶端，通过细胞质动力蛋白1B向下游运送到细胞体。这种运输的主要功能被认为是将一批轴突前体运送到轴突组装部位的上游。也有人假设，IFT的功能是将信号从纤毛和鞭毛的尖端向下游输送到细胞体，从而介导外部刺激的信号转导。IFT货物的这种转移必须涉及IFT RAFT蛋白与鞭毛结构蛋白的相互作用。与这一假设一致，我们发现三个IFT RAFT蛋白p57、p88和p172中的每一个都含有不同的重复氨基酸序列。其中，p57的螺旋卷曲基序和p88的四肽重复序列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基因突变，(2)鉴定与这三个IFT RAFT亚基直接相关的蛋白质。这些研究将使我们在分子水平上了解IFT颗粒如何在真核生物纤毛和鞭毛的组装和功能过程中转运它们的货物。这些研究的结果可能会导致有效治疗睫状肌依赖性疾病，包括Kartag‘s综合征。