title: Ultrafast endocytosis at mouse hippocampal synapses.
abstract: To sustain neurotransmission, synaptic vesicles and their associated proteins must be recycled locally at synapses. Synaptic vesicles are thought to be regenerated approximately 20 s after fusion by the assembly of clathrin scaffolds or in approximately 1 s by the reversal of fusion pores via 'kiss-and-run' endocytosis. Here we use optogenetics to stimulate cultured hippocampal neurons with a single stimulus, rapidly freeze them after fixed intervals and examine the ultrastructure using electron microscopy--'flash-and-freeze' electron microscopy. Docked vesicles fuse and collapse into the membrane within 30 ms of the stimulus. Compensatory endocytosis occurs within 50 to 100 ms at sites flanking the active zone. Invagination is blocked by inhibition of actin polymerization, and scission is blocked by inhibiting dynamin. Because intact synaptic vesicles are not recovered, this form of recycling is not compatible with kiss-and-run endocytosis; moreover, it is 200-fold faster than clathrin-mediated endocytosis. It is likely that 'ultrafast endocytosis' is specialized to restore the surface area of the membrane rapidly.
authors.affiliation: Department of Biology and Howard Hughes Medical Institute, University of Utah, Salt Lake City, Utah, U.S.A.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Watanabe
authors.affiliation: Neuroscience Research Centre, Charité Universitätsmedizin, Berlin, Germany.
authors.forename: Benjamin R
authors.initials: BR
authors.lastname: Rost
authors.affiliation: Neuroscience Research Centre, Charité Universitätsmedizin, Berlin, Germany.
authors.forename: Marcial
authors.initials: M
authors.lastname: Camacho-Pérez
authors.affiliation: Department of Biology and Howard Hughes Medical Institute, University of Utah, Salt Lake City, Utah, U.S.A.
authors.forename: M Wayne
authors.initials: MW
authors.lastname: Davis
authors.affiliation: Neuroscience Research Centre, Charité Universitätsmedizin, Berlin, Germany.
authors.forename: Berit
authors.initials: B
authors.lastname: Söhl-Kielczynski
authors.affiliation: Neuroscience Research Centre, Charité Universitätsmedizin, Berlin, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Rosenmund
authors.affiliation: Department of Biology and Howard Hughes Medical Institute, University of Utah, Salt Lake City, Utah, U.S.A.
authors.forename: Erik M
authors.initials: EM
authors.lastname: Jorgensen
mesh_terms: D000199:Actins / Q000378:metabolism / Q000648:ultrastructure; D000200:Action Potentials; D000818:Animals; D034281:Dynamins / Q000378:metabolism / Q000648:ultrastructure; D004705:Endocytosis; D005089:Exocytosis; D006624:Hippocampus / Q000166:cytology*; D008561:Membrane Fusion; D051379:Mice; D008854:Microscopy, Electron; D012243:Rhodopsin / Q000235:genetics / Q000378:metabolism; D013569:Synapses / Q000378:metabolism* / Q000648:ultrastructure; D009435:Synaptic Transmission; D013572:Synaptic Vesicles / Q000378:metabolism / Q000648:ultrastructure; D013997:Time Factors
chemical_list: D000199:Actins; D012243:Rhodopsin; D034281:Dynamins