FAPP2调控极化上皮细胞顶膜分选过程的分子机制研究

The polarized distribution of proteins and lipids at the surface membrane of epithelial cells results in the formation of an apical and a basolateral domains,which are separated by tigh junctions.The generation and maintenance of epithelial polarity require elaborate mechanisms that guarantee correct sorting and vectorial delivery of cargo molecules to their destination. Apical sorting is a critical step in this dynamic and complicated process.Much advance has been made in recent years,especially since raft concept had been introduced into this field,however, many questions still remain elusive, such as detailed sorting process and apical carrier formation.In this proposal, we combine multidiscipilinary methods to study molecular mechanism of FAPP2, the 4-phosphate adaptor protein 2,in apical sorting in polarized epithelial cells, specially through evaluation of protein-mediated rafts domain clustering dynamics. It is a highly novel and unconventional approach wherein biophysical membrane parameters are bridged to a classical paradigm in cell biology. We aim to dissect molecular mechanism of FAPP2 in cargo sorting and vesicle budding in model membrane system and in vivo.Furthermore,we try to explore pathomechanism of some diseases resulted from loss of FAPP2 function in FAPP2 knock-out mouse and identify important players in apical sorting routs as target moleculars for drug, which will provide theoretical basis for intervention of related diseases.

蛋白质与脂类分子在极化上皮细胞膜表面不均一分布导致形成了被紧密连接分隔且功能各异的顶膜和底模。上皮细胞极性的建立和维持要求一套精细的分子机制来正确分选和传递货物分子。顶膜分选是这一动态而复杂过程中的关键步骤。近年来，特别是脂筏概念引入，这一领域取得了重要进步，然而，顶膜货物分子分选过程以及运输囊泡的形成的分子机制等问题仍停留在假说阶段，有待于进一步的实验证实。本课题将运用多学科的方法，聚焦于四磷酸接头蛋白FAPP2，研究其在极化上皮细胞顶膜分选过程中的详细机制。通过在模式膜系统评估蛋白介导的筏成串动力学，综合反映膜特性变化的生物物理参数和经典的细胞生物学机制研究数据，分别从体外和体内剖析FAPP2在顶膜分选和囊泡出芽过程的分子机制。进而在FAPP2 knock out小鼠中寻找FAPP2功能丧失所致疾病的病理机制以及可作为药物靶标的重要分子，为相关疾病的干预奠定理论基础。