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Regulation of Clathrin-mediated Endocytosis by AP2 complexes

Final Report Summary - CME-REG (Regulation of Clathrin-mediated Endocytosis by AP2 complexes)

The plasma membrane represents the interface between cells and their neighborhood, mediating diverse processes such as cell–cell communication, cell–matrix interactions and uptake of nutrients. As a result, clathrin mediated endocytosis (CME) has a central role in maintaining cellular homeostasis and function and mis-regulation of endocytic traffic is linked to many human diseases. Yet, the mechanisms regulating CME remain poorly understood. In this project we aimed to define the role(s) of the adaptor protein-2 (AP2) in regulating CME. Using state-of-the-art molecular cell biology we generated stable cell lines expressing WT and functionally defined AP2 mutants. These were analysed by live cell total internal reflection fluorescence microscopy, in combination with sophisticated particle tracking algorithms and mathematical analyses to measure effects on discrete early stages of CME. We determined how PI4,5P2, cargo, clathrin and endocytic accessory factor binding to AP2, as well as phosphorylation events trigger conformational changes in AP2 to regulate initial events in clathrin coated pit (CCP) assembly, stabilization of nascent CCPs and their maturation. Together these studies tested the hypothesis that allosteric conformational changes in AP2 play a central role in regulating early, critical events in CME. These interdisciplinary studies benefited from combining and transferring the most up-to-date experimental techniques and expertise in molecular cell biology, structural biology, microscopy, and mathematics. The collaboration between outgoing and European host fully ensured the expertise that was necessary to accomplish this complex goal. Most importantly it gave an opportunity to the researcher for training and career development in leading research institutions under the guidance of mentors who are world experts in their respective fields. All the project tasks, deliverables and outcomes are summarized in the attached document Publication_CME_REG_1.