Molecular mechanisms of basolateral targeting in polarized epithelial cells

描述(申请人提供)：极化上皮细胞排列在每个器官中，对人体的功能至关重要。上皮细胞的中心功能是建立和维持生化和功能上不同的膜域，顶膜面向器官的管腔，基侧膜与结缔组织接触。两层膜由紧密的连接处隔开。为了维持这种结构，上皮细胞必须不断地将新合成和内化的跨膜受体分类到生物合成和内吞途径中正确的膜域。我们的工作重点是确保从中央分选站-循环内小体-正确靶向基底侧膜的分子机制。以前，我们证明了前往基侧膜的货物可以被上皮特异性的网状蛋白适配器复合体AP-1B识别，从而整合到AP-1B囊泡中。这项拨款申请建议对这些发现进行跟踪，并研究AP-1B功能、膜招募的分子机制，以及AP-1B依赖的途径从内小体循环到基侧膜的调节。我们将利用遗传学、生化和细胞生物学方法来实现我们的研究目标。 与公共健康相关：上皮细胞的主要功能是确保人体和环境之间正确的营养和废物交换。为了实现这些不同的功能，上皮细胞的表面被划分为生化和功能上不同的膜域。我们的长期目标是了解极化上皮细胞如何建立和维持这种不对称性，重点关注导致跨膜受体正确定位到面对结缔组织和邻近细胞的膜域的过程。

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.