Activated human hydroxy‐carboxylic acid receptor‐3 signals to MAP kinase cascades via the PLC‐dependent PKC and MMP‐mediated EGFR pathways

• Published in: British journal of pharmacology 2012-07, Vol.166 (6), p.1756-1773
• Main Authors: Zhou, Q, Li, G, Deng, XY, He, XB, Chen, LJ, Wu, C, Shi, Y, Wu, KP, Mei, LJ, Lu, JX, Zhou, NM
• Format: Article
• Language: English
• Subjects: A431; Animals; Arrestins - metabolism; beta-Arrestins; Biological and medical sciences; Calcium - metabolism; cAMP; CHO Cells; Cricetinae; Cricetulus; Cyclic AMP - metabolism; Dipeptides - pharmacology; EGFR; ERK1/2; GTP-Binding Protein alpha Subunits, Gi-Go - metabolism; HCA2; HCA3; HEK293 Cells; Humans; MAP Kinase Kinase 1 - metabolism; MAP Kinase Kinase 2 - metabolism; MAP Kinase Signaling System - drug effects; Medical sciences; Metalloendopeptidases - antagonists & inhibitors; Metalloendopeptidases - metabolism; Mitogen-Activated Protein Kinase 1 - metabolism; Mitogen-Activated Protein Kinase 3 - metabolism; PDGFR; Pharmacology. Drug treatments; PKC; PLC; Protein Kinase C - metabolism; Receptor, Epidermal Growth Factor - metabolism; Receptors, G-Protein-Coupled - metabolism; Receptors, Nicotinic - metabolism; Research Papers; β‐arrestins
• ISSN: 0007-1188; 1476-5381
• DOI: 10.1111/j.1476-5381.2012.01875.x

BACKGROUND AND PURPOSE 3‐Hydroxy‐octanoate, recently identified as a ligand for, the orphan GPCR, HCA3, is of particular interest given its ability to treat lipid disorders and atherosclerosis. Here we demonstrate the pathway of HCA3‐mediated activation of ERK1/2. EXPERIMENTAL APPROACH Using CHO‐K1 cells stably expressing HCA3 receptors and A431 cells, a human epidermoid cell line with high levels of endogenous expression of functional HCA3 receptors, HCA3‐mediated activation of ERK1/2 was measured by Western blot. KEY RESULTS HCA3‐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, HCA3 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 Gi protein play a critical role in HCA3‐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 HCA3 receptors to the ERK1/2 MAP kinase pathway in CHO‐K1 and A431 cells, which implicate the Gi 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 HCA3‐mediated activation of ERK1/2.