title: AGAP1/AP-3-dependent endocytic recycling of M5 muscarinic receptors promotes dopamine release.
abstract: Of the five mammalian muscarinic acetylcholine (ACh) receptors, M(5) is the only subtype expressed in midbrain dopaminergic neurons, where it functions to potentiate dopamine release. We have identified a direct physical interaction between M(5) and the AP-3 adaptor complex regulator AGAP1. This interaction was specific with regard to muscarinic receptor (MR) and AGAP subtypes, and mediated the binding of AP-3 to M(5). Interaction with AGAP1 and activity of AP-3 were required for the endocytic recycling of M(5) in neurons, the lack of which resulted in the downregulation of cell surface receptor density after sustained receptor stimulation. The elimination of AP-3 or abrogation of AGAP1-M(5) interaction in vivo decreased the magnitude of presynaptic M(5)-mediated dopamine release potentiation in the striatum. Our study argues for the presence of a previously unknown receptor-recycling pathway that may underlie mechanisms of G-protein-coupled receptor (GPCR) homeostasis. These results also suggest a novel therapeutic target for the treatment of dopaminergic dysfunction.
authors.affiliation: Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, NY 10065, USA. jacobbendor@gmail.com
authors.forename: Jacob
authors.initials: J
authors.lastname: Bendor
authors.forename: José E
authors.initials: JE
authors.lastname: Lizardi-Ortiz
authors.forename: Robert I
authors.initials: RI
authors.lastname: Westphalen
authors.forename: Markus
authors.initials: M
authors.lastname: Brandstetter
authors.forename: Hugh C
authors.initials: HC
authors.lastname: Hemmings
authors.forename: David
authors.initials: D
authors.lastname: Sulzer
authors.forename: Marc
authors.initials: M
authors.lastname: Flajolet
authors.forename: Paul
authors.initials: P
authors.lastname: Greengard
mesh_terms: D033963:Adaptor Protein Complex 3 / Q000032:analysis / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D003342:Corpus Striatum / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D004705:Endocytosis; D005260:Female; D020690:GTPase-Activating Proteins / Q000032:analysis / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D009474:Neurons / Q000166:cytology; D017434:Protein Structure, Tertiary; D051381:Rats; D017207:Rats, Sprague-Dawley; D043642:Receptor, Muscarinic M5 / Q000032:analysis / Q000378:metabolism*; D016415:Sequence Alignment
chemical_list: C552282:AGAP1 protein, mouse; D033963:Adaptor Protein Complex 3; C552281:Agap1 protein, rat; D020690:GTPase-Activating Proteins; D043642:Receptor, Muscarinic M5; D004298:Dopamine