title: Calcyon is necessary for activity-dependent AMPA receptor internalization and LTD in CA1 neurons of hippocampus.
abstract: Calcyon is a single transmembrane endocytic protein that regulates clathrin assembly and clathrin-mediated endocytosis in the brain. Ultrastructural studies indicate that calcyon localizes to spines, but whether it regulates glutamate neurotransmission is not known. Here, we show that deletion of the calcyon gene in mice inhibits agonist-stimulated endocytosis of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs), without altering basal surface levels of the GluR1 or GluR2 subunits. Whole-cell patch-clamp studies of hippocampal neurons in culture and CA1 synapses in slices revealed that knockout (KO) of calcyon abolishes long-term synaptic depression (LTD), whereas mini-analysis in slices indicated basal transmission in the hippocampus is unaffected by the deletion. Further, transfection of green fluorescent protein-tagged calcyon rescued the ability of KO cultures to undergo LTD. In contrast, intracellular dialysis of a fusion protein containing the clathrin light-chain-binding domain of calcyon blocked the induction of LTD in wild-type hippocampal slices. Taken together, the present studies involving biochemical, immunological and electrophysiological analyses raise the possibility that calcyon plays a specialized role in regulating activity-dependent removal of synaptic AMPARs.
authors.affiliation: Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta, GA 30912-2300, USA.
authors.forename: Heather Trantham
authors.initials: HT
authors.lastname: Davidson
authors.forename: Jiping
authors.initials: J
authors.lastname: Xiao
authors.forename: Rujuan
authors.initials: R
authors.lastname: Dai
authors.forename: Clare
authors.initials: C
authors.lastname: Bergson
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002966:Clathrin / Q000378:metabolism; D004705:Endocytosis / Q000502:physiology*; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D049452:Green Fluorescent Proteins; D006624:Hippocampus / Q000378:metabolism*; D036881:Long-Term Synaptic Depression / Q000187:drug effects / Q000502:physiology*; D008565:Membrane Proteins / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D011485:Protein Binding / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology; D018091:Receptors, AMPA / Q000187:drug effects / Q000378:metabolism*; D013569:Synapses / Q000187:drug effects / Q000378:metabolism; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology
chemical_list: D002966:Clathrin; D018690:Excitatory Amino Acid Agonists; D008565:Membrane Proteins; D018091:Receptors, AMPA; C405464:calcyon; D049452:Green Fluorescent Proteins