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Ichijo Y, Mochimaru Y, Azuma M, Satou K, Negishi J, Nakakura T, Oshima N, Mogi C, Sato K, Matsuda K, Okajima F, Tomura H. Two zebrafish G2A homologs activate multiple intracellular signaling pathways in acidic environment. Biochem Biophys Res Commun 2015; 469:81-86. [PMID: 26614909 DOI: 10.1016/j.bbrc.2015.11.075] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Accepted: 11/17/2015] [Indexed: 01/01/2023]
Abstract
Human G2A is activated by various stimuli such as lysophosphatidylcholine (LPC), 9-hydroxyoctadecadienoic acid (9-HODE), and protons. The receptor is coupled to multiple intracellular signaling pathways, including the Gs-protein/cAMP/CRE, G12/13-protein/Rho/SRE, and Gq-protein/phospholipase C/NFAT pathways. In the present study, we examined whether zebrafish G2A homologs (zG2A-a and zG2A-b) could respond to these stimuli and activate multiple intracellular signaling pathways. We also examined whether histidine residue and basic amino acid residue in the N-terminus of the homologs also play roles similar to those played by human G2A residues if the homologs sense protons. We found that the zG2A-a showed the high CRE, SRE, and NFAT activities, however, zG2A-b showed only the high SRE activity under a pH of 8.0. Extracellular acidification from pH 7.4 to 6.3 ameliorated these activities in zG2A-a-expressing cells. On the other hand, acidification ameliorated the SRE activity but not the CRE and NFAT activities in zG2A-b-expressing cells. LPC or 9-HODE did not modify any activity of either homolog. The substitution of histidine residue at the 174(th) position from the N-terminus of zG2A-a to asparagine residue attenuated proton-induced CRE and NFAT activities but not SRE activity. The substitution of arginine residue at the 32nd position from the N-terminus of zG2A-a to the alanine residue also attenuated its high and the proton-induced CRE and NFAT activities. On the contrary, the substitution did not attenuate SRE activity. The substitution of the arginine residue at the 10th position from the N-terminus of zG2A-b to the alanine residue also did not attenuate its high or the proton-induced SRE activity. These results indicate that zebrafish G2A homologs were activated by protons but not by LPC and 9-HODE, and the activation mechanisms of the homologs were similar to those of human G2A.
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Affiliation(s)
- Yuta Ichijo
- Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki 214-8571, Japan
| | - Yuta Mochimaru
- Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki 214-8571, Japan
| | - Morio Azuma
- Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of Toyama, 3190-Gofuku, Toyama 930-8555, Japan
| | - Kazuhiro Satou
- Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki 214-8571, Japan
| | - Jun Negishi
- Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki 214-8571, Japan
| | - Takashi Nakakura
- Department of Anatomy, Graduate School of Medicine, Teikyo University, 2-11-1 Itabashi-Ku, Tokyo 173-8605, Japan
| | - Natsuki Oshima
- Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki 214-8571, Japan
| | - Chihiro Mogi
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Japan
| | - Koichi Sato
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Japan
| | - Kouhei Matsuda
- Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of Toyama, 3190-Gofuku, Toyama 930-8555, Japan
| | - Fumikazu Okajima
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Japan
| | - Hideaki Tomura
- Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki 214-8571, Japan.
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