title: Protein kinase inhibitor β enhances the constitutive activity of G-protein-coupled zinc receptor GPR39.
abstract: GPR39 is a G-protein-coupled zinc receptor that protects against diverse effectors of cell death. Its protective activity is mediated via constitutive activation of Gα13 and the RhoA pathway, leading to increased SRE (serum-response element)-dependent transcription; the zinc-dependent immediate activation of GPR39 involves Gq-mediated increases in cytosolic Ca2+ and Gs coupling leading to increased cAMP levels. We used the cytosolic and soluble C-terminus of GPR39 in a Y2H (yeast-2-hybrid) screen for interacting proteins, thus identifying PKIB (protein kinase A inhibitor β). Co-expression of GPR39 with PKIB increased the protective activity of GPR39 via the constitutive, but not the ligand-mediated, pathway. PKIB inhibits protein kinase A by direct interaction with its pseudosubstrate domain; mutation of this domain abolished the inhibitory activity of PKIB on protein kinase A activity, but had no effect on the interaction with GPR39, cell protection and induction of SRE-dependent transcription. Zinc caused dissociation of PKIB from GPR39, thereby liberating it to associate with protein kinase A and inhibit its activity, which would result in a negative-feedback loop with the ability to limit activation of the Gs pathway by zinc.
authors.affiliation: *Department of Neurology, Medical Faculty, Heinrich Heine Universität Düsseldorf, Düsseldorf, Germany.
authors.forename: Zsuzsa
authors.initials: Z
authors.lastname: Kovacs
authors.affiliation: †Focus Program Translational Neuroscience (FTN), Rhine Main Neuroscience Network (rmn2), Johannes Gutenberg University Medical Center Mainz, Department of Neurology, Langenbeckstr. 1, D-55131 Mainz, Germany.
authors.forename: Teresa
authors.initials: T
authors.lastname: Schacht
authors.affiliation: †Focus Program Translational Neuroscience (FTN), Rhine Main Neuroscience Network (rmn2), Johannes Gutenberg University Medical Center Mainz, Department of Neurology, Langenbeckstr. 1, D-55131 Mainz, Germany.
authors.forename: Ann-Kathrin
authors.initials: AK
authors.lastname: Herrmann
authors.affiliation: *Department of Neurology, Medical Faculty, Heinrich Heine Universität Düsseldorf, Düsseldorf, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Albrecht
authors.affiliation: ‡Harvard Medical School, Brigham and Women's Hospital and the VA Boston Healthcare System, Boston, MA, U.S.A.
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Lefkimmiatis
authors.affiliation: †Focus Program Translational Neuroscience (FTN), Rhine Main Neuroscience Network (rmn2), Johannes Gutenberg University Medical Center Mainz, Department of Neurology, Langenbeckstr. 1, D-55131 Mainz, Germany.
authors.forename: Axel
authors.initials: A
authors.lastname: Methner
mesh_terms: D000818:Animals; D016466:CHO Cells; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003412:Cricetulus; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000096:biosynthesis / Q000502:physiology*; D051379:Mice; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D015032:Zinc / Q000378:metabolism / Q000494:pharmacology
chemical_list: C495797:GPR39 protein, human; D047908:Intracellular Signaling Peptides and Proteins; C107591:PKIB protein, human; D047428:Protein Kinase Inhibitors; D043562:Receptors, G-Protein-Coupled; D017868:Cyclic AMP-Dependent Protein Kinases; D015032:Zinc