title: Activated human hydroxy-carboxylic acid receptor-3 signals to MAP kinase cascades via the PLC-dependent PKC and MMP-mediated EGFR pathways.
abstract: BACKGROUND AND PURPOSE 3-Hydroxy-octanoate, recently identified as a ligand for, the orphan GPCR, HCA(3), is of particular interest given its ability to treat lipid disorders and atherosclerosis. Here we demonstrate the pathway of HCA(3)-mediated activation of ERK1/2. EXPERIMENTAL APPROACH Using CHO-K1 cells stably expressing HCA(3) receptors and A431 cells, a human epidermoid cell line with high levels of endogenous expression of functional HCA(3) receptors, HCA(3)-mediated activation of ERK1/2 was measured by Western blot. KEY RESULTS HCA(3)-mediated activation of ERK1/2 was rapid, peaking at 5 min, and was Pertussis toxin sensitive. Our data, obtained by time course analyses in combination with different kinase inhibitors, demonstrated that on agonist stimulation, HCA(3) receptors evoked ERK1/2 activation via two distinct pathways, the PLC/PKC pathway at early time points (≤ 2 min) and the MMP/ epidermal growth factor receptor (EGFR) transactivation pathway with a maximum response at 5 min. Furthermore, our present results also indicated that the βγ-subunits of the G(i) protein play a critical role in HCA(3)-activated ERK1/2 phosphorylation, whereas β-arrestins and Src were not required for ERK1/2 activation. CONCLUSIONS AND IMPLICATIONS We have described the molecular mechanisms underlying the coupling of human HCA(3) receptors to the ERK1/2 MAP kinase pathway in CHO-K1 and A431 cells, which implicate the G(i) protein-initiated, PLC/PKC -and platelet-derived growth factor receptor/EGFR transactivation-dependent pathways. These observations may provide new insights into the pharmacological effects and the physiological functions modulated by the HCA(3)-mediated activation of ERK1/2.
authors.affiliation: Zhejiang Provincial Key Laboratory of Medical Genetics, School of Laboratory Medicine and Life Science, Wenzhou Medical College, Wenzhou, Zhejiang, China.
authors.forename: Q
authors.initials: Q
authors.lastname: Zhou
authors.forename: G
authors.initials: G
authors.lastname: Li
authors.forename: X Y
authors.initials: XY
authors.lastname: Deng
authors.forename: X B
authors.initials: XB
authors.lastname: He
authors.forename: L J
authors.initials: LJ
authors.lastname: Chen
authors.forename: C
authors.initials: C
authors.lastname: Wu
authors.forename: Y
authors.initials: Y
authors.lastname: Shi
authors.forename: K P
authors.initials: KP
authors.lastname: Wu
authors.forename: L J
authors.initials: LJ
authors.lastname: Mei
authors.forename: J X
authors.initials: JX
authors.lastname: Lu
authors.forename: N M
authors.initials: NM
authors.lastname: Zhou
mesh_terms: D000818:Animals; D019390:Arrestins / Q000378:metabolism; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D006224:Cricetinae; D003412:Cricetulus; D000242:Cyclic AMP / Q000378:metabolism; D004151:Dipeptides / Q000494:pharmacology; D066246:ErbB Receptors / Q000378:metabolism*; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D048369:MAP Kinase Kinase 1 / Q000378:metabolism; D048370:MAP Kinase Kinase 2 / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008666:Metalloendopeptidases / Q000037:antagonists & inhibitors / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D011978:Receptors, Nicotinic / Q000378:metabolism*; D000071557:beta-Arrestins
chemical_list: D019390:Arrestins; D004151:Dipeptides; C473653:HCAR3 protein, human; C078131:N-(2(R)-2-(hydroxamidocarbonylmethyl)-4-methylpentanoyl)-L-tryptophan methylamide; D043562:Receptors, G-Protein-Coupled; D011978:Receptors, Nicotinic; D000071557:beta-Arrestins; D000242:Cyclic AMP; D066246:ErbB Receptors; D011493:Protein Kinase C; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; D008666:Metalloendopeptidases; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D002118:Calcium