The Mechanism of Pericentriolar Material Assembly During Centrosome Biogenesis

描述(申请人提供)：中心体是由一对中心粒组成，周围环绕着一种无定形的中心粒周围物质(PCM)的蛋白质网络，是许多细胞功能的基本成分，包括微管组装和纤毛形成。中心体生物发生缺陷会导致男性不育、多种癌症和各种发育障碍。这些发育障碍的例子包括囊性肾病、Bardet-Biedl综合征、左右不对称和小头畸形。显然，适当的中心体生物发生对人类健康是必不可少的。毫不奇怪，中心体的生物发生是一个复杂的、多步骤的过程。特别是，中心粒周围的物质(PCM)必须聚集在中心粒周围，以使得到的中心体发挥作用。调控PCM最初如何形成、被招募到中心粒并聚集在中心粒周围的机制仍然是一个谜；该提案的目标是解开这个谜。实现这一目标将从关注最近发现的细胞质PCM复合体开始。这个复合体包括多种已知在患有小头畸形症患者中存在缺陷的蛋白质，小头畸形症是一种大脑大小严重缩小的疾病。本文的目的是分析(1)SAS-4与微管蛋白之间潜在的关键相互作用，(2)SAS-4复合体在纤毛形成中的作用，以及(3)SAS-4复合体在星形微管形成中的作用。这些目标将通过在模式生物黑腹果蝇中结合遗传学和生物化学的跨学科方法来实现。果蝇具有几个良好的特性，这使得它成为研究中心体生物发生的理想工具。首先，目前有许多中心体生物发生突变体可用。虽然这些突变体中的许多是成虫致死的，但它们不是胚胎或幼虫致死的；因此，果蝇是唯一可以详细研究中心体生物发生突变的动物之一。其次，果蝇胚胎可以被大量收集，这为中心体生物发生提供了丰富的蛋白质来源；然后这些蛋白质可以用于生化和体外实验。第三，果蝇的其他众所周知的特征，如世代时间短和遗传容易，使其成为许多生物系统的首选模式生物，也与该项目有关。果蝇的这些有利特性将有助于发现PCM的形成和组装机制；这一发现将有助于开发由中心体生物发生缺陷引起的人类疾病的诊断和治疗方法。

DESCRIPTION (provided by applicant): Centrosomes, which are composed of a pair of centrioles surrounded by an amorphous protein network of pericentriolar material (PCM), are fundamental cellular components that are critical for many cellular functions including microtubule assembly and cilia formation. Defective centrosome biogenesis causes male infertility, numerous types of cancer, and various developmental disorders. Examples of these developmental disorders are cystic kidney disease, Bardet-Biedl syndrome, left-right asymmetry, and Microcephaly. Clearly, proper centrosomes biogenesis is essential to human health. Not surprisingly, centrosome biogenesis is a complex, multi-step process. In particular, pericentriolar material (PCM) must assemble around a centriole for the resulting centrosome to function. The mechanisms regulating how PCM initially forms, is recruited to a centriole, and assembles around the centriole, remain a mystery; the proposal's goal is to solve that mystery. Achieving this goal will begin by focusing on a recently discovered cytoplasmic PCM complex. This complex includes multiple proteins known to be defective in patients suffering from Microcephaly, a disorder where brain size is severely reduced. The aims proposed here are to analyze (1) a potentially key interaction between Sas-4 and tubulin, (2), the role of Sas-4 complexes in cilia formation and (3) the role of Sas-4 complexes in astral microtubule formation. These aims will be accomplished using an interdisciplinary approach that combines genetics and biochemistry in the model organism Drosophila melanogaster. Drosophila possesses several favorable characteristics, which makes it ideal for studying centrosome biogenesis. First, numerous centrosome biogenesis mutants are currently available. Although many of these mutants are adult lethal, they are not embryonic or pupal lethal; thus, Drosophila is one of the only animals in which centrosome biogenesis mutants can be studied in detail. Second, Drosophila embryos can be collected in mass, which provides a plentiful source of the proteins involved in centrosome biogenesis; these proteins can then be used in biochemical and in vitro experiments. Third, other well-known characteristics of Drosophila, e.g., short generation time and ease of genetics, which have made it a preferred model organism for many biological systems, are also relevant to this project. These favorable characteristics of Drosophila should permit discovery of the mechanism of PCM formation and assembly; this discovery should aid in the development of diagnostic and treatment methods for human disorders caused by defective centrosome biogenesis.