title: PKCε phosphorylates α4β2 nicotinic ACh receptors and promotes recovery from desensitization.
abstract: OBJECTIVE
  Nicotinic (ACh) receptor recovery from desensitization is modulated by PKC, but the PKC isozymes and the phosphorylation sites involved have not been identified. We investigated whether PKCε phosphorylation of α4β2 nAChRs regulates receptor recovery from desensitization.
  
  
  METHODS
  Receptor recovery from desensitization was investigated by electrophysiological characterization of human α4β2 nAChRs. Phosphorylation of the α4 nAChR subunit was assessed by immunoblotting of mouse synaptosomes. Hypothermia induced by sazetidine-A and nicotine was measured in Prkce(-/-) and wild-type mice.
  
  
  RESULTS
  Inhibiting PKCε impaired the magnitude of α4β2 nAChR recovery from desensitization. We identified five putative PKCε phosphorylation sites in the large intracellular loop of the α4 subunit, and mutating four sites to alanines also impaired recovery from desensitization. α4 nAChR subunit phosphorylation was reduced in synaptosomes from Prkce(-/-) mice. Sazetidine-A-induced hypothermia, which is mediated by α4β2 nAChR desensitization, was more severe and prolonged in Prkce(-/-) than in wild-type mice.
  
  
  CONCLUSIONS
  PKCε phosphorylates the α4 nAChR subunit and regulates recovery from receptor desensitization. This study illustrates the importance of phosphorylation in regulating α4β2 receptor function, and suggests that reducing phosphorylation prolongs receptor desensitization and decreases the number of receptors available for activation.
authors.affiliation: Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA.
authors.forename: A M
authors.initials: AM
authors.lastname: Lee
authors.affiliation: Division of Pharmacology and Toxicology, College of Pharmacy, University of Texas at Austin, Austin, TX, USA.
authors.forename: D-F
authors.initials: DF
authors.lastname: Wu
authors.affiliation: Division of Pharmacology and Toxicology, College of Pharmacy, University of Texas at Austin, Austin, TX, USA.
authors.forename: J
authors.initials: J
authors.lastname: Dadgar
authors.affiliation: Ernest Gallo Clinic and Research Center, University of California at San Francisco, Emeryville, CA, USA.
authors.forename: D
authors.initials: D
authors.lastname: Wang
authors.affiliation: Ernest Gallo Clinic and Research Center, University of California at San Francisco, Emeryville, CA, USA.
authors.forename: T
authors.initials: T
authors.lastname: McMahon
authors.affiliation: Division of Pharmacology and Toxicology, College of Pharmacy, University of Texas at Austin, Austin, TX, USA.
authors.forename: R O
authors.initials: RO
authors.lastname: Messing
mesh_terms: D000818:Animals; D006801:Humans; D007035:Hypothermia / Q000139:chemically induced / Q000503:physiopathology; D008297:Male; D051379:Mice; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009538:Nicotine / Q000494:pharmacology; D010766:Phosphorylation / Q000502:physiology; D051744:Protein Kinase C-epsilon / Q000378:metabolism*; D011978:Receptors, Nicotinic / Q000378:metabolism*; D020127:Recovery of Function / Q000187:drug effects / Q000502:physiology*
chemical_list: D011978:Receptors, Nicotinic; C403531:nicotinic receptor alpha4beta2; D009538:Nicotine; D051744:Protein Kinase C-epsilon