Identifying Signaling Mechanisms Controlling Flagellar Length in Chlamydomonas

描述(申请人提供)：纤毛是以微管为基础的细胞器，从大多数哺乳动物细胞的表面突出出来，具有从调节身体对称性到感觉功能的各种功能。纤毛的形成和维持的异常往往具有不同的病理后果，因为这些细胞器几乎无处不在。纤毛的结构和组装高度保守，很容易在单细胞绿藻衣藻的活动鞭毛中进行研究。这些细胞上的鞭毛的长度对细胞外和细胞内的环境有很高的反应。了解感知异常并对长度变化作出反应的信号机制以及内在长度确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控的未知信号分子的功能，包括GPCR和包含脂肪酶结构域的蛋白质FAP12。我还将研究已知的长度调节蛋白LF1p、LF2p、LF3p和LF4p的复杂相互作用，以确定它们如何相互作用，严格控制鞭毛长度。最后，我将使用插入突变筛选长鞭毛突变体的抑制物来鉴定这一途径中的新成分。 与公共卫生相关：识别和表征可以控制几乎无处不在的纤毛细胞器长度的信号分子，将使我们对纤毛大小异常引起的纤毛疾病有重要的见解。具体地说，测试纤毛长度调节复合体的特定作用，并在调节纤毛长度的通路中识别新的成分，将为广泛的纤毛疾病的治疗干预提供许多新的潜在靶点。这些纤毛疾病包括多囊肾病、肾小球肾炎、Bardet-Biedl综合征、脑积水、视网膜变性等。

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.