Diacylglycerol Guides the Hopping of Clathrin-Coated PITs along Microtubules for Exo-Endocytosis Coupling

Abstract

Many receptor-mediated endocytic processes are mediated by constitutively budding of clathrin-coated pits (CCPs) at spatially randomized sites before slowly pinching-off from the plasma membrane (60∼100 s). In contrast, clathrin-mediated endocytosis (CME) coupled with regulated exocytosis in excitable cells occurs at peri-exocytic sites shortly after vesicle fusion (∼10 s). The molecular mechanism underlying this spatiotemporal coupling remains elusive. We show that coupled endocytosis makes use of pre-formed CCPs, which hop to nascent fusion sites nearby following vesicle exocytosis. A dynamic cortical microtubular network, anchored at the cell surface by the cytoplasmic linker-associated protein on microtubules and the LL5β/ELKS complex on the plasma membrane, provides the track for CCP hopping. Local diacylglycerol gradients generated upon exocytosis guide the direction of hopping. Overall, the CCP-cytoskeleton-lipid interaction demonstrated here mediates exocytosis-coupled fast recycling of both plasma membrane and vesicular proteins, and is required for the sustained exocytosis during repetitive stimulations.