Free fatty acids and protein kinase C activation induce GPR120 (free fatty acid receptor 4) phosphorylation

• Published in: European journal of pharmacology Vol. 723; pp. 368 - 374
• Main Authors: Sánchez-Reyes, Omar B., Romero-Ávila, M. Teresa, Castillo-Badillo, Jean A., Takei, Yoshinori, Hirasawa, Akira, Tsujimoto, Gozoh, Villalobos-Molina, Rafael, García-Sáinz, J. Adolfo
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.01.2014
• Subjects: alpha-Linolenic Acid - pharmacology; Docosahexaenoic Acids - pharmacology; Fatty Acids, Nonesterified - pharmacology; Free fatty acid receptor 4; GPR120; HEK293 Cells; Humans; Phorbol Esters - pharmacology; Phosphorylation; Protein kinase C; Protein Kinase C - metabolism; Receptor phosphorylation; Receptors, G-Protein-Coupled - metabolism; Recombinant Fusion Proteins - metabolism; Tetradecanoylphorbol Acetate - pharmacology; FFA; Protein kinase C; GPR120; GPCR; PKC; DHA; Free fatty acid receptor 4; Receptor phosphorylation; TIRF; α-LA
• ISSN: 0014-2999; 1879-0712
• DOI: 10.1016/j.ejphar.2013.11.003

GPR120, free fatty acid receptor 4, is a recently deorphanized G protein-coupled receptor that seems to play cardinal roles in the regulation of metabolism and in the pathophysiology of inflammatory and metabolic disorders. In the present work a GPR120-Venus fusion protein was expressed in HEK293 Flp-In T-REx cells and its function (increase in intracellular calcium) and phosphorylation were studied. It was observed that the fusion protein migrated in sodium dodecyl sulfate-polyacrylamide gels as a band with a mass of ≈70–75kDa, although other bands of higher apparent weight (>130kDa) were also detected. Cell stimulation with docosahexaenoic acid or α-linolenic acid induced concentration-dependent increases in intracellular calcium and GPR120 phosphorylation. Activation of protein kinase C with phorbol esters also induced a marked receptor phosphorylation but did not alter the ability of 1µM docosahexaenoic acid to increase the intracellular calcium concentration. Phorbol ester-induced GPR120 phosphorylation, but not that induced with docosahexaenoic acid, was blocked by protein kinase C inhibitors (bis-indolyl-maleimide I and Gö 6976) suggesting that conventional kinase isoforms mediate this action. The absence of effect of protein kinase C inhibitors on agonist-induced GPR120 phosphorylation indicates that this kinase does not play a major role in agonist-induced receptor phosphorylation. Docosahexaenoic acid action was associated with marked GPR120 internalization whereas that induced with phorbol esters was smaller at early times.