Regulation of melanocortin-1 receptor pharmacology by melanocortin receptor accessory protein 2 in orange-spotted grouper (Epinephelus coioides)

• Published in: General and comparative endocrinology Vol. 285; p. 113291
• Main Authors: Ji, Li-Qin, Rao, Ying-Zhu, Zhang, Yong, Chen, Rong, Tao, Ya-Xiong
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.01.2020
• Subjects: Adaptor Proteins, Signal Transducing - metabolism; Amino Acid Sequence; Animals; Base Sequence; Bass - genetics; Bass - metabolism; Cyclic AMP - metabolism; Epinephelus coioides; Fish Proteins - metabolism; Gene Expression Regulation; HEK293 Cells; Humans; Ligands; MAP Kinase Signaling System; Melanocortin receptor accessory protein 2; Melanocortin-1 receptor; Orange-spotted grouper; Pharmacology; Phylogeny; Receptor, Melanocortin, Type 1 - chemistry; Receptor, Melanocortin, Type 1 - genetics; Receptor, Melanocortin, Type 1 - metabolism; Signal Transduction - drug effects; Tissue distribution; Epinephelus coioides; Melanocortin-1 receptor; Pharmacology; Orange-spotted grouper; Tissue distribution; Melanocortin receptor accessory protein 2
• ISSN: 0016-6480; 1095-6840
• DOI: 10.1016/j.ygcen.2019.113291

•Grouper mc1r was primarily expressed in the brain, skin, testis, and spleen.•Grouper MC1R showed high constitutive activities in both Gs-cAMP and ERK1/2 pathways.•Grouper MRAP2 decreased MC1R cell surface expression.•Grouper MRAP2 decreased basal and agonist-stimulated cAMP generation.•Grouper MRAP2 increased MC1R basal ERK1/2 signaling. Melanocortin-1 receptor (MC1R) has important roles in regulating pigmentation and inflammation. Melanocortin receptor accessory protein 2 (MRAP2) modulates trafficking, ligand binding, and signaling of mammalian melanocortin receptors. However, the effect of MRAP2 on fish MC1R has not been extensively studied. Herein, we cloned the orange-spotted grouper (Epinephelus coioides) mc1r, which had a 972 bp open reading frame encoding a putative protein of 323 amino acids. Grouper mc1r was mainly expressed in the brain, skin, testis, spleen, head kidney, and kidney. EcoMC1R showed high constitutive activities in both Gs-cAMP and ERK1/2 pathways, which could be differentially modulated by grouper MRAP2 (EcoMRAP2). Three agonists, including α-melanocyte-stimulating hormone (MSH), β-MSH, and ACTH, could bind to EcoMC1R and dose-dependently increase intracellular cAMP production. EcoMRAP2 had no effect on the IC50 in binding assay or EC50 in cAMP assay; however, it dose-dependently decreased the cell surface expression and maximal response to the three agonists. EcoMRAP2 increased basal ERK1/2 activation but did not alter α-MSH-stimulated ERK1/2 activation. This study extends the knowledge base of fish MC1R pharmacology and its regulation by MRAP2.