title: AKAP signaling in reinstated cocaine seeking revealed by iTRAQ proteomic analysis.
abstract: To identify candidate proteins in the nucleus accumbens (NAc) as potential pharmacotherapeutic targets for treating cocaine addition, an 8-plex iTRAQ (isobaric tag for relative and absolute quantitation) proteomic screen was performed using NAc tissue obtained from rats trained to self-administer cocaine followed by extinction training. Compared with yoked-saline controls, 42 proteins in a postsynaptic density (PSD)-enriched subfraction of the NAc from cocaine-trained animals were identified as significantly changed. Among proteins of interest whose levels were identified as increased was AKAP79/150, the rat ortholog of human AKAP5, a PSD scaffolding protein that localizes signaling molecules to the synapse. Functional downregulation of AKAP79/150 by microinjecting a cell-permeable synthetic AKAP (A-kinase anchor protein) peptide into the NAc to disrupt AKAP-dependent signaling revealed that inhibition of AKAP signaling impaired the reinstatement of cocaine seeking. Reinstatement of cocaine seeking is thought to require upregulated surface expression of AMPA glutamate receptors, and the inhibitory AKAP peptide reduced the PSD content of protein kinase A (PKA) as well as surface expression of GluR1 in NAc. However, reduced surface expression was not associated with changes in PKA phosphorylation of GluR1. This series of experiments demonstrates that proteomic analysis provides a useful tool for identifying proteins that can regulate cocaine relapse and that AKAP proteins may contribute to relapse vulnerability by promoting increased surface expression of AMPA receptors in the NAc.
authors.affiliation: Departments of Neurosciences, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
authors.forename: Kathryn J
authors.initials: KJ
authors.lastname: Reissner
authors.forename: Joachim D
authors.initials: JD
authors.lastname: Uys
authors.forename: John H
authors.initials: JH
authors.lastname: Schwacke
authors.forename: Susanna
authors.initials: S
authors.lastname: Comte-Walters
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Rutherford-Bethard
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Dunn
authors.forename: Joe B
authors.initials: JB
authors.lastname: Blumer
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Schey
authors.forename: Peter W
authors.initials: PW
authors.lastname: Kalivas
mesh_terms: D054758:A Kinase Anchor Proteins / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D015153:Blotting, Western; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D019970:Cocaine-Related Disorders / Q000523:psychology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology; D008297:Male; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000235:genetics; D016571:Neural Networks, Computer; D009714:Nucleus Accumbens / Q000502:physiology; D040901:Proteomics / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000096:biosynthesis / Q000235:genetics; D012646:Self Administration; D015398:Signal Transduction / Q000187:drug effects*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D013569:Synapses / Q000502:physiology
chemical_list: D054758:A Kinase Anchor Proteins; D017868:Cyclic AMP-Dependent Protein Kinases; D009419:Nerve Tissue Proteins; D018091:Receptors, AMPA