title: Adaptor protein complexes 1 and 3 are essential for generation of synaptic vesicles from activity-dependent bulk endosomes.
abstract: Activity-dependent bulk endocytosis is the dominant synaptic vesicle retrieval mode during high intensity stimulation in central nerve terminals. A key event in this endocytosis mode is the generation of new vesicles from bulk endosomes, which replenish the reserve vesicle pool. We have identified an essential requirement for both adaptor protein complexes 1 and 3 in this process by employing morphological and optical tracking of bulk endosome-derived synaptic vesicles in rat primary neuronal cultures. We show that brefeldin A inhibits synaptic vesicle generation from bulk endosomes and that both brefeldin A knockdown and shRNA knockdown of either adaptor protein 1 or 3 subunits inhibit reserve pool replenishment from bulk endosomes. Conversely, no plasma membrane function was found for adaptor protein 1 or 3 in either bulk endosome formation or clathrin-mediated endocytosis. Simultaneous knockdown of both adaptor proteins 1 and 3 indicated that they generated the same population of synaptic vesicles. Thus, adaptor protein complexes 1 and 3 play an essential dual role in generation of synaptic vesicles during activity-dependent bulk endocytosis.
authors.affiliation: Centre for Integrative Physiology, University of Edinburgh, Edinburgh, Scotland EH8 9XD, United Kingdom.
authors.forename: Giselle
authors.initials: G
authors.lastname: Cheung
authors.forename: Michael A
authors.initials: MA
authors.lastname: Cousin
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000235:genetics; D033961:Adaptor Protein Complex 1 / Q000235:genetics / Q000378:metabolism*; D033963:Adaptor Protein Complex 3 / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D020126:Brefeldin A / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology; D003911:Dextrans / Q000378:metabolism; D011992:Endosomes / Q000187:drug effects / Q000502:physiology*; D005089:Exocytosis / Q000187:drug effects / Q000235:genetics; D005260:Female; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006735:Horseradish Peroxidase / Q000494:pharmacology; D008297:Male; D009474:Neurons / Q000166:cytology* / Q000187:drug effects; D018408:Patch-Clamp Techniques; D011189:Potassium Chloride / Q000494:pharmacology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D012235:Rhodamines / Q000378:metabolism; D013572:Synaptic Vesicles / Q000187:drug effects / Q000378:metabolism*; D014162:Transfection / Q000379:methods
chemical_list: D033961:Adaptor Protein Complex 1; D033963:Adaptor Protein Complex 3; D003911:Dextrans; C067661:Fluoro-Ruby; D011500:Protein Synthesis Inhibitors; D034741:RNA, Small Interfering; D012235:Rhodamines; D049452:Green Fluorescent Proteins; D020126:Brefeldin A; D011189:Potassium Chloride; D006735:Horseradish Peroxidase