The phospho-dependent dynamin-syndapin interaction triggers activity-dependent bulk endocytosis of synaptic vesicles.
Synaptic vesicles (SVs) are retrieved by more than one mode in central nerve terminals. During mild stimulation, the dominant SV retrieval pathway is classical clathrin-mediated endocytosis (CME). During elevated neuronal activity, activity-dependent bulk endocytosis (ADBE) predominates, which requires activation of the calcium-dependent protein phosphatase calcineurin. We now report that calcineurin dephosphorylates dynamin I in nerve terminals only above the same activity threshold that triggers ADBE. ADBE was arrested when the two major phospho-sites on dynamin I were perturbed, suggesting that dynamin I dephosphorylation is a key step in its activation. Dynamin I dephosphorylation stimulates a specific dynamin I-syndapin I interaction. Inhibition of this interaction by competitive peptides or by site-directed mutagenesis exclusively inhibited ADBE but did not affect CME. The results reveal that the phospho-dependent dynamin-syndapin interaction recruits ADBE to massively increase SV endocytosis under conditions of elevated neuronal activity.
Clayton
Emma L
EL
Membrane Biology Group, Centre for Integrative Physiology, George Square, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom.
Anggono
Victor
V
Smillie
Karen J
KJ
Chau
Ngoc
N
Robinson
Phillip J
PJ
Cousin
Michael A
MA
D000200:Action Potentials / Q000502:physiology; D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D019703:Calcineurin / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology; D003598:Cytoskeletal Proteins; D003911:Dextrans / Q000378:metabolism; D034284:Dynamin I / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004558:Electric Stimulation / Q000379:methods; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology*; D020558:GTP Phosphohydrolases / Q000378:metabolism; D006735:Horseradish Peroxidase / Q000378:metabolism; D006835:Hydrazones / Q000494:pharmacology; D016253:Microscopy, Immunoelectron / Q000379:methods; D016297:Mutagenesis, Site-Directed / Q000379:methods; D009433:Neural Inhibition / Q000502:physiology; D009474:Neurons / Q000166:cytology* / Q000187:drug effects; D009841:Oligonucleotides / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects / Q000502:physiology; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012694:Serine / Q000378:metabolism; D013572:Synaptic Vesicles / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D016708:Synaptophysin / Q000378:metabolism; D013997:Time Factors; D014162:Transfection / Q000379:methods
D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D003911:Dextrans; D006835:Hydrazones; C511794:N'-(3,4-dihydroxybenzylidene)-3-hydroxy-2-naphthahydrazide; D009841:Oligonucleotides; C117738:Pacsin1 protein, rat; D016708:Synaptophysin; D012694:Serine; D011189:Potassium Chloride; D006735:Horseradish Peroxidase; D019703:Calcineurin; D034284:Dynamin I; D020558:GTP Phosphohydrolases; D002118:Calcium