title: Effects of arachidonic acid on FFA4 receptor: Signaling, phosphorylation and internalization.
abstract: Arachidonic acid increased intracellular calcium, in cells expressing green fluorescent protein-tagged human FFA4 receptors, with an EC50of ~40µM. This action was not blocked by cyclooxygenase or lipoxigenase inhibitors but it was inhibited by AH7614, a FFA4 antagonist. Arachidonic acid induced ERK activation accompanied by EGF receptor transactivation. However, EGF transactivation was not the major mechanism through which the fatty acid induced ERK phosphorylation, as evidenced by the inability of AG1478 to block it. Arachidonic acid increased FFA4 receptor phosphorylation that reached its maximum within 15min with an EC50of ~30µM; inhibitors of protein kinase C partially diminish this effect and AH7614 blocked it. Arachidonic acid induced rapid and sustained Akt/PKB phosphorylation and FFA4 - β-arrestin interaction. Confocal microscopy evidenced that FFA4 receptor activation and phosphorylation were associated to internalization. In conclusion, arachidonic acid is a bona fide FFA4 receptor agonist.
authors.affiliation: Instituto de Fisiología Celular, Universidad Nacional Autónoma de México. Ap., Postal 70-248, Ciudad de México 04510, Mexico.
authors.forename: S
authors.initials: S
authors.lastname: Villegas-Comonfort
authors.affiliation: Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Takei
authors.affiliation: Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: G
authors.initials: G
authors.lastname: Tsujimoto
authors.affiliation: Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Hirasawa
authors.affiliation: Instituto de Fisiología Celular, Universidad Nacional Autónoma de México. Ap., Postal 70-248, Ciudad de México 04510, Mexico. Electronic address: agarcia@ifc.unam.mx.
authors.forename: J A
authors.initials: JA
authors.lastname: García-Sáinz
mesh_terms: D016718:Arachidonic Acid / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D066246:ErbB Receptors / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D010766:Phosphorylation; D011799:Quinazolines / Q000494:pharmacology; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D020032:Tyrphostins / Q000494:pharmacology; D000071557:beta-Arrestins / Q000378:metabolism
chemical_list: C519853:FFAR4 protein, human; D011799:Quinazolines; D043562:Receptors, G-Protein-Coupled; D020032:Tyrphostins; D000071557:beta-Arrestins; C101044:RTKI cpd; D016718:Arachidonic Acid; C512478:EGFR protein, human; D066246:ErbB Receptors; D048049:Extracellular Signal-Regulated MAP Kinases; D002118:Calcium
keywords: ERK phosphorylation; FFA4 internalization; FFA4 phosphorylation; GPR120