Synaptic vesicle recycling at CNS snapses without AP-2.

TitleSynaptic vesicle recycling at CNS snapses without AP-2.
Publication TypeJournal Article
Year of Publication2009
AuthorsKim SHyun, Ryan TA
JournalJ Neurosci
Date Published2009 Mar 25
KeywordsAction Potentials, Adaptor Protein Complex 1, Adaptor Protein Complex 2, Adaptor Protein Complex mu Subunits, ADP-Ribosylation Factors, Animals, Animals, Newborn, Brefeldin A, Endocytosis, Gene Knockdown Techniques, Gene Silencing, GTP Phosphohydrolases, Guanine Nucleotide Exchange Factors, Kinetics, Neurons, Rats, Rats, Sprague-Dawley, Synaptic Vesicles

Synaptic vesicles (SVs) are composed of approximately 10 types of transmembrane proteins that must be recycled after exocytosis of neurotransmitter. The mechanisms for resorting these proteins into synaptic vesicles once incorporated into the plasma membrane after exocytosis are poorly understood. The adaptor complex AP-2 is the major clathrin-associated adaptor for cargo recognition at the plasma membrane. Here, we have investigated its role in synaptic vesicle endocytosis. shRNA-mediated knockdown of the AP-2 complex results in an approximately 96% reduction of this protein complex in primary neurons. We used simultaneous expression of shRNA and pHluorin-tagged vesicle components to show that the absence of AP-2 significantly slows but does not prevent the endocytosis of four of the major synaptic vesicle transmembrane proteins. We show that in the absence of AP-2, the AP-1 adaptor complex appears to functionally substitute for AP-2 but results in complex internalization kinetics that are now sensitive to the guanine-nucleotide exchange factor for ADP-ribosylation factor GTPase (ARF-GEF) inhibitor brefeldin-A (BFA). Simultaneous removal of both AP-2 and AP-1 prevents this compensatory substitution and results in slowed but functional endocytosis. These results demonstrate that in the absence of AP-2, SV proteins still become endocytosed, and synaptic vesicle recycling remains operational.

Alternate JournalJ. Neurosci.
PubMed ID19321783
PubMed Central IDPMC2713063
Grant ListR01 NS036942-12 / NS / NINDS NIH HHS / United States