Regulation of Flagellar Assembly in Chlamydomonas

描述（由申请人提供）：本研究的长期目标是了解真核细胞用于调节纤毛和鞭毛组装的机制。衣藻的鞭毛保持恒定长度，但LF1、LF2、LF3和LF4四种不同基因的突变导致细胞失去组装控制，鞭毛长度可达正常长度的三倍。其中两个基因编码的成员已经被充分研究的基因家族：一个MAP激酶和一个CDK激酶家族。对四个LF基因的分析得出结论，LF4是一种新的MAP激酶，通过缩短鞭毛来控制鞭毛长度。LF1， LF2和LF3似乎共同作用来调节长度，可能是通过调节逆行鞭毛内运输（IFT）。在下一个项目期间，该项目的具体目标将解决以下问题：l)哪些蛋白质调节LF4基因编码的MAP激酶酶，LF4p磷酸化哪些蛋白质？2)假设的LF1/LF2/LF3细胞质复合体中的蛋白质如何相互作用，该复合体如何调节LF2蛋白激酶？3) LF2蛋白激酶的蛋白底物是什么？这些靶点的磷酸化是如何调节鞭毛长度的？4)长鞭毛突变体是否表现出鞭毛内运输（IFT）的改变？人们早就知道纤毛和鞭毛在液体在表面上运动或细胞在液体中运动的过程中起着关键作用。最近，纤毛和鞭毛在发育早期起着至关重要的作用。纤毛和鞭毛组装缺陷与多囊肾病、视网膜变性、倒位和哺乳动物发育中的其他问题有关。了解衣藻鞭毛组装的调控为理解哺乳动物系统中鞭毛组装提供了一个强有力的模型。

DESCRIPTION (provided by applicant): The long-term goal of this research is to understand the mechanisms eukaryotic cells use to regulate the assembly of cilia and flagella. The flagella of Chlamydomonas are maintained at a constant length, but mutations in four different genes: LF1, LF2, LF3 and LF4, cause the cells to lose control of assembly and grow flagella up to three times normal length. Two of these genes encode members of well-studied gene families: a MAP kinase and a kinase of the CDK family. Analysis of the four LF genes leads to the conclusion that LF4, a novel MAP kinase, acts to enforce flagellar length control by shortening the flagella. LF1, LF2 and LF3 appear to act together to regulate length, perhaps by regulating retrograde intraflagellar transport (IFT). During the next project period the specific aims of this project will address the following questions:l) What proteins regulate the MAP kinase enzyme encoded by the LF4 gene, and what proteins does LF4p phosphorylate? 2) How do the proteins in the putative LF1/LF2/LF3 cytoplasmic complex interact, and how does this complex regulate the LF2 protein kinase? 3) What are the protein substrates of the LF2 protein kinase and how does phosphorylation of these targets regulate flagellar length? 4) Do the long-flagella mutants show alterations in intraflagellar transport (IFT)? Cilia and flagella have long been known to play key roles in processes that involve the movement of fluids over surfaces or the movement of cells through fluids. More recently it has become clear that cilia and flagella have critical functions early in development. Defects in the assembly of cilia and flagella have been connected to polycystic kidney disease retinal degeneration, situs inversus, and other problems in mammalian development. Understanding the regulation of flagellar assembly in Chlamydomonas provides a powerful model for understanding this assembly in mammalian systems.