Dynamin I phosphorylation by GSK3 controls activity-dependent bulk endocytosis of synaptic vesicles.
Glycogen synthase kinase 3 (GSK3) is a critical enzyme in neuronal physiology; however, it is not yet known whether it has any specific role in presynaptic function. We found that GSK3 phosphorylates a residue on the large GTPase dynamin I (Ser-774) both in vitro and in primary rat neuronal cultures. This was dependent on prior phosphorylation of Ser-778 by cyclin-dependent kinase 5. Using both acute inhibition with pharmacological antagonists and silencing of expression with short hairpin RNA, we found that GSK3 was specifically required for activity-dependent bulk endocytosis (ADBE) but not clathrin-mediated endocytosis. Moreover we found that the specific phosphorylation of Ser-774 on dynamin I by GSK3 was both necessary and sufficient for ADBE. These results demonstrate a presynaptic role for GSK3 and they indicate that a protein kinase signaling cascade prepares synaptic vesicles for retrieval during elevated neuronal activity.
Centre for Integrative Physiology, George Square, University of Edinburgh, Edinburgh, Scotland, UK.
Emma L
EL
Clayton
Nancy
N
Sue
Karen J
KJ
Smillie
Timothy
T
O'Leary
Nicolai
N
Bache
Giselle
G
Cheung
Adam R
AR
Cole
David J
DJ
Wyllie
Calum
C
Sutherland
Phillip J
PJ
Robinson
Michael A
MA
Cousin
D000818:Animals; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000378:metabolism; D051360:Cyclin-Dependent Kinase 5 / Q000378:metabolism; D034284:Dynamin I / Q000378:metabolism*; D004705:Endocytosis / Q000502:physiology*; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism*; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D010766:Phosphorylation / Q000502:physiology; D017729:Presynaptic Terminals / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000502:physiology; D013572:Synaptic Vesicles / Q000378:metabolism*
D051360:Cyclin-Dependent Kinase 5; D038362:Glycogen Synthase Kinase 3; D034284:Dynamin I