Identifying Signaling Mechanisms Controlling Flagellar Length in Chlamydomonas

描述（由申请人提供）：纤毛是基于微管的细胞器，从大多数哺乳动物细胞表面突出，具有从调节身体对称性到感觉功能等功能。由于纤毛细胞器的普遍存在，纤毛的形成和维持异常往往会导致不同的病理后果。单细胞绿藻莱茵衣藻（Chlamydomonas reinhardtii）的活动鞭毛中纤毛的结构和组装高度保守，易于研究。这些细胞上鞭毛的长度对细胞外和细胞内环境高度敏感。了解感知异常和响应长度变化的信号机制，以及了解固有长度决定的机制，对于确定纤毛相关病理的来源至关重要。为了解决这个核心问题，我将首先确定在鞭毛组装过程中不受调节的未表征信号分子的功能，包括GPCR和含有脂肪酶结构域的蛋白FAP12。我还将研究已知长度调节蛋白LF1p， LF2p， LF3p和LF4p的复杂相互作用，以确定它们如何相互作用以严格控制鞭毛长度。最后，我将使用插入诱变筛选长鞭毛突变体的抑制因子来鉴定这一途径中的新成分。

DESCRIPTION (provided by applicant): Cilia are microtubule-based organelles that protrude from the surface of most mammalian cells for functions ranging from regulating body symmetry to sensory functions. Abnormalities in formation and maintenance of cilia often have variable pathologic consequences due to the near-ubiquity of these organelles. The structure and assembly of cilia are highly conserved and are readily studied in the motile flagella of the unicellular green alga Chlamydomonas reinhardtii. The length of flagella on these cells is highly responsive to the extracellular and intracellular environment. Understanding the signaling mechanisms involved in sensing abnormalities and responding with changes in length, as well as understanding the mechanisms involved in intrinsic length determination are critically important for identifying sources of cilia related pathology. To tackle this central question, I will first identify the function of uncharacterized signaling molecules that are unregulated during flagellar assembly including a GPCR and a lipase domain containing protein, FAP12. I will also investigate the complex interactions of known length-regulating proteins LF1p, LF2p, LF3p and LF4p to determine how they act with one another for tight control of flagellar length. Finally I will identify novel components in this pathway using an insertional mutagenesis screen for suppressors of a long flagella mutant. PUBLIC HEALTH RELEVANCE: Identifying and characterizing signaling molecules that can control the length of the nearly ubiquitous ciliary organelle will give us significant insights into the ciliopathies that result from abnormal cilium size. Specifically, testing the specific role of cilia length regulation complexes and identifying novel components in pathways regulating length will provide many new potential targets for therapeutic intervention in a wide range of ciliopathies. These ciliopathies include polycystic kidney disease, nephronophthisis, Bardet-Biedl syndrome, hydrocephalus, retinal degeneration and many others.