Cell Surface Recognition and Cell Interactions

细胞表面识别和细胞相互作用

• 批准号: 7821397
• 负责人: William J Snell
• 金额: $ 37.69万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 1978
• 资助国家: 美国
• 起止时间: 1978-07-01 至 2013-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7821397
• 关键词: Adenylate Cyclase; Adhesions; Agglutinins; Binding; Biochemical; Biological Models; Cell Communication; Cell Cycle; Cell fusion; Cell surface; Cells; Chlamydomonas; Chlamydomonas reinhardtii; Cilia; Complex; Coupling; Cyclic AMP; Cyclic GMP-Dependent Protein Kinases; Development; Elements; Flagella; Funding; Generations; Germ Cells; Goals; Green Algae; Homeostasis; Human Development; Immigration; Kinesin; Laboratories; Link; Mammalian Cell; Membrane; Microtubules; Modeling; Molecular; Movement; Organelles; Partner in relationship; Pathway interactions; Phosphorylation; Property; Protein Kinase; Protein Tyrosine Kinase; Proteins; Reaction; Regulation; Research; Role; Signal Pathway; Signal Transduction; Stress; Testing; Tubulin; adhesion receptor; genetic regulatory protein; insight; mutant; neuronal cell body; novel; particle; public health relevance; receptor; research study; trafficking; zygote

DESCRIPTION (provided by applicant): The long-term goals of my research are to understand the cellular and molecular properties of cilia/flagella that underlie their functions. My laboratory uses the biflagellated green alga Chlamydomonas reinhardtii as a model system to study cilium-generated signaling and ciliary/flagellar shortening. During the Chlamydomonas mating reaction, adhesion receptors (agglutinins) on the flagella of minus gametes bind to their cognate agglutinins on the flagella of plus gametes, thereby activating a cilium-generated signaling pathway in both cells that activates the gametes for cell-cell fusion to form a zygote. Immediately after zygote formation (and also during experimentally-imposed stress), Chlamydomonas cells shorten and completely resorb their flagella. We propose to use Chlamydomonas to dissect novel functions and mechanisms of regulation of the intraflagellar transport (IFT) machinery. Because almost every mammalian cell possesses a primary cilium that is used for signal transduction and also must be resorbed during cell cycle entry, our studies will provide novel insights into fundamental cellular mechanisms essential for human development and homeostasis. In previous studies of flagellar adhesion-induced signaling, we had shown that a regulatory protein, a flagellar protein tyrosine kinase (PTK), was activated early in the pathway. Moreover, using mutant gametes conditionally defective in IFT, we presented evidence that IFT is required for signal transduction in an intact cilium/flagellum. In the current funding period we discovered that a second regulatory protein in the pathway, a cGMP-dependent protein kinase, becomes associated with large assemblies within flagella whose formation requires IFT. To our surprise, the large, newly formed assemblies also contain IFT particles. Here, in our studies on signaling, we propose experiments to test the model that, in addition to its roles in flagellar assembly and disassembly, the IFT machinery participates directly in cilium-generated signaling and links membrane receptor interactions to gamete activation. Our previous studies on flagellar shortening showed that an aurora-like protein kinase (CALK) was essential for regulated shortening. In the current funding period, we made the surprising discovery that IFT trafficking within flagella and cargo loading onto IFT particles in the cell body are regulated during shortening. Moreover, we found that a protein that disassembles microtubules, a depolymerizing kinesin, in the cell body is phosphorylated and transported into flagella as microtubule disassembly is triggered during shortening. Our specific aims are to dissect the function of the intraflagellar transport machinery in flagellar adhesion-induced signaling, investigate the molecules that couple flagellar adhesion to gamete activation, and study the cellular and molecular mechanisms of flagellar shortening. PUBLIC HEALTH RELEVANCE: Primary cilia carry out key signaling roles in development and homeostasis and they are resorbed before cell cycle entry. Yet, we know little about the cellular and molecular mechanisms of cilium-generated signaling or ciliary disassembly. Studying flagellar adhesion and flagellar shortening in Chlamydomonas will continue to uncover novel and fundamental properties of these remarkable organelles.

描述（由申请人提供）：我的长期研究目标是了解纤毛/鞭毛的细胞和分子特性，这些特性是其功能的基础。我的实验室以双鞭毛绿藻莱茵衣藻（Chlamydomonas reinhardtii）为模型系统，研究纤毛产生的信号和纤毛/鞭毛缩短。在衣单胞菌的交配反应中，负配子鞭毛上的粘附受体（凝集素）与正配子鞭毛上的同源凝集素结合，从而激活两个细胞中纤毛产生的信号通路，激活配子进行细胞-细胞融合形成合子。在合子形成后（以及在实验施加的压力下），衣藻细胞立即缩短并完全吸收其鞭毛。我们建议使用衣藻来剖析鞭毛内运输（IFT）机制的新功能和调节机制。由于几乎每个哺乳动物细胞都具有用于信号转导的初级纤毛，并且在细胞周期进入过程中必须被吸收，因此我们的研究将为人类发育和体内平衡所必需的基本细胞机制提供新的见解。在之前的鞭毛粘附诱导信号的研究中，我们已经证明了一种调节蛋白，鞭毛蛋白酪氨酸激酶（PTK），在该途径的早期被激活。此外，利用IFT有条件缺陷的突变配子，我们证明了完整纤毛/鞭毛的信号转导需要IFT。在目前的资助期内，我们发现该途径中的第二种调节蛋白，一种cgmp依赖性蛋白激酶，与鞭毛内的大组装相关，鞭毛的形成需要IFT。令我们惊讶的是，大的、新形成的组装体也含有IFT粒子。在这里，在我们的信号研究中，我们提出了实验来测试这个模型，除了在鞭毛组装和拆卸中起作用外，IFT机制直接参与纤毛产生的信号传导，并将膜受体相互作用与配子激活联系起来。我们之前对鞭毛缩短的研究表明，极光样蛋白激酶（CALK）对调节缩短是必不可少的。在目前的资助期内，我们惊奇地发现鞭毛内的IFT运输和细胞体中装载到IFT颗粒上的货物在缩短过程中受到调节。此外，我们发现细胞体中的一种分解微管的蛋白，即解聚驱动蛋白，在短缩过程中被磷酸化并转运到鞭毛中。我们的具体目的是剖析鞭毛粘附诱导的信号传递中鞭毛内运输机制的功能，研究鞭毛粘附与配子激活耦合的分子，研究鞭毛缩短的细胞和分子机制。