Role of activation of PIP5Kγ661 by AP-2 complex in synaptic vesicle endocytosis

Synaptic vesicles (SVs) are retrieved by clathrin-mediated endocytosis at the nerve terminals. Phosphatidylinositol 4,5-bisphosphate [PI( 4,5) P-2] drives this event by recruiting the components of the endocytic machinery. However, the molecular mechanisms that result in local generation of PI( 4,5) P-2 remain unclear. We demonstrate here that AP-2 complex directly interacts with phosphatidylinositol 4-phosphate 5-kinase gamma 661 (PIP5Kc661), the major PI(4,5) P-2-producing enzyme in the brain. The beta 2 subunit of AP-2 was found to bind to the C-terminal tail of PIP5Kc661 and cause PIP5Kc661 activation. The interaction is regulated by PIP5Kc661 dephosphorylation, which is triggered by depolarization in mouse hippocampal neurons. Finally, overexpression of the PIP5Kc661 C-terminal region in hippocampal neurons suppresses depolarization-dependent SV endocytosis. These findings provide evidence for the molecular mechanism through which PIP5Kc661 locally generates PI( 4,5) P-2 in hippocampal neurons and suggest a model in which the interaction trigger SV endocytosis.