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

摘要: Many receptor-mediated endocytic processes are mediated by constitutive budding of clathrin-coated pits (CCPs) at spatially randomized sites before slowly pinching off from the plasma membrane (60100 s). In contrast, clathrin-mediated endocytosis (CME) coupled with regulated exocytosis in excitable cells occurs at peri-exocytic sites shortly after vesicle fusion (similar to 10 s). The molecular mechanism underlying this spatiotemporal coupling remains elusive. We show that coupled endocytosis makes use of preformed 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 LL5 beta/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 it is required for the sustained exocytosis during repetitive stimulations.