Clathrin-mediated endocytosis is the dominant mechanism of vesicle retrieval at hippocampal synapses.
The maintenance of synaptic transmission requires that vesicles be recycled after releasing neurotransmitter. Several modes of retrieval have been proposed to operate at small synaptic terminals of central neurons, including a fast "kiss-and-run" mechanism that releases neurotransmitter through a fusion pore. Using an improved fluorescent reporter comprising pHluorin fused to synaptophysin, we find that only a slow mode of endocytosis (tau = 15 s) operates at hippocampal synapses when vesicle fusion is triggered by a single nerve impulse or short burst. This retrieval mechanism is blocked by overexpression of the C-terminal fragment of AP180 or by knockdown of clathrin using RNAi, and it is associated with the movement of clathrin and vesicle proteins out of the synapse. These results indicate that clathrin-mediated endocytosis is the major, if not exclusive, mechanism of vesicle retrieval after physiological stimuli.
Granseth
Björn
B
MRC Laboratory of Molecular Biology, Hills Road, Cambridge, CB2 2QH, United Kingdom.
Odermatt
Benjamin
B
Royle
Stephen J
SJ
Lagnado
Leon
L
D000818:Animals; D002478:Cells, Cultured; D002966:Clathrin / Q000235:genetics / Q000378:metabolism*; D022163:Clathrin-Coated Vesicles / Q000378:metabolism*; D004705:Endocytosis / Q000502:physiology*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology / Q000502:physiology*; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D013569:Synapses / Q000502:physiology*; D016708:Synaptophysin / Q000235:genetics / Q000378:metabolism; D014162:Transfection
D002966:Clathrin; D009419:Nerve Tissue Proteins; C485187:PHluorin; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D016708:Synaptophysin; C514578:synaptopHIuorin; D049452:Green Fluorescent Proteins