Protein kinase inhibitor β enhances the constitutive activity of G-protein-coupled zinc receptor GPR39.

Journal article

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: Kovacs, Z; Schacht, T; Herrmann, A; Albrecht, P; Lefkimmiatis, K

• Publisher: Portland Press Ltd
• Journal: Biochemical journal
• Volume: 462
• Issue: 1
• Pages: 125-132
• Publication date: 2014-08-01
• DOI: 10.1042/bj20131198
• EISSN: 1470-8728
• ISSN: 0264-6021
• Language: English
• Keywords: Protein Kinase Inhibitors; CHO Cells; Cell Membrane; Hela Cells; Cell Line; Intracellular Signaling Peptides and Proteins; Humans; Two-Hybrid System Techniques; Mice; Receptors, G-Protein-Coupled; Zinc; Animals; Cricetulus; Cyclic AMP-Dependent Protein Kinases