Molecular mechanisms of basolateral targeting in polarized epithelial cells

描述（由申请人提供）：极化上皮细胞排列在每个器官上，对人体功能至关重要。上皮细胞功能的核心是建立和维持生物化学和功能上不同的膜域，面向器官管腔的顶膜和与结缔组织接触的基底侧膜。两层膜被紧密连接分开。为了维持这种结构，上皮细胞必须在生物合成和内吞途径中不断地将新合成和内化的跨膜受体分类到正确的膜结构域。我们的工作重点是确保从中央分拣站，回收核内体正确靶向基侧膜的分子机制。先前的研究表明，运往基底外侧膜的货物被上皮特异性网格蛋白接头复合物AP-1B识别，并被纳入AP-1B囊泡。这项拨款申请旨在跟进这些发现，并研究AP-1B功能、膜募集的分子机制，以及从循环核内体到基底外膜的AP-1B依赖途径的调控。我们将采用遗传、生化和细胞生物学的方法来完成我们的研究目标。

DESCRIPTION (provided by applicant): Polarized epithelial cells line every organ and are of utmost importance for the function of the human body. Central to epithelial cell function is the establishment and maintenance of biochemically and functionally distinct membrane domains, the apical membrane facing the lumen of an organ and the basolateral membrane that is in contact with connective tissues. Both membranes are separated by tight junctions. To maintain this architecture, epithelial cells must continuously sort newly synthesized and internalized transmembrane receptors to the correct membrane domains in the biosynthetic and endocytic pathways. Our work focuses on the molecular mechanisms that ensure correct targeting to the basolateral membrane from a central sorting station, the recycling endosomes. Previously we showed that cargos destined for the basolateral membrane are recognized by the epithelial-specific clathrin adaptor complex AP-1B for incorporation into AP-1B vesicles. This grant application proposes to follow up on these findings and to investigate the molecular mechanisms of AP-1B function, membrane recruitment, and regulation of the AP-1B-dependent pathway from recycling endosomes to the basolateral membrane. We will employ genetical, biochemical, and cell biological methods to accomplish our research goals. PUBLIC HEALTH RELEVANCE: The primary function of epithelial cells is to ensure the correct nutrient and waste product exchange between the body and the environment. To fulfill these different functions, the surface of epithelial cells is divided into biochemically and functionally distinct membrane domains. Our long-term goal is to understand how polarized epithelial cells establish and maintain this asymmetry with a focus on processes that lead to correct targeting of transmembrane receptors to the membrane domain that faces connective tissues and neighboring cells.