Molecular cloning, tissue distribution, and pharmacological characterization of melanocortin-4 receptor in grass carp (Ctenopharyngodon idella)

• Published in: Domestic animal endocrinology Vol. 59; pp. 140 - 151
• Main Authors: Li, L., Yang, Z., Zhang, Y.-P., He, S., Liang, X.-F., Tao, Y.-X.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-04-2017
• Subjects: Amino Acid Sequence; Animals; Base Sequence; Carps - genetics; Cloning, Molecular; Expression; Gene Expression Regulation - physiology; Grass carp; HEK293 Cells; Humans; Ligand binding; Melanocortin-4 receptor; Phylogeny; Receptor, Melanocortin, Type 4 - genetics; Receptor, Melanocortin, Type 4 - metabolism; Signaling; Tissue Distribution; Ligand binding; Signaling; Grass carp; Melanocortin-4 receptor; Expression
• ISSN: 0739-7240; 1879-0054
• DOI: 10.1016/j.domaniend.2016.11.004

Melanocortin-4 receptor (MC4R) plays a pivotal role in the mediation of leptin action on food intake and energy expenditure in mammals. The MC4R has also been identified in several teleosts, and its importance in the regulation of fish energy homeostasis is emerging. We herein reported on the molecular cloning, tissue distribution, and pharmacological characterization of MC4R in grass carp (Ctenopharyngodon idella), an economically and ecologically important fish. We showed that grass carp MC4R (ciMC4R) consisted of a 981 bp open reading frame encoding a protein of 326 amino acids, highly homologous (>95%) to several teleost MC4Rs. Phylogenetic and synteny analysis further indicated ciMC4R was closely related to piscine MC4Rs. Using reverse transcription PCR, we found that mc4r messenger RNA was expressed in the brain as well as various peripheral tissues in grass carp. The pharmacological properties of ciMC4R were investigated using 4 agonists, including α-melanocyte stimulating hormone (α-MSH), β-MSH, [Nle4, D-Phe7]-MSH (NDP-MSH), and adrenocorticotropic hormone (ACTH). We showed that all 4 ligands could bind to ciMC4R and initiate dose-dependent intracellular cyclic adenosine monophosphate (cAMP) accumulation. Grass carp MC4R had the highest affinity for NDP-MSH. Both NDP-MSH and ACTH (1–24) exhibited higher potencies compared to the other 2 endogenous agonists. The ciMC4R was constitutively active, with significantly increased basal cAMP level compared with that of human MC4R (P < 0.01). The availability of ciMC4R and its pharmacologic characteristics provide a basis for future investigation of its functional roles in regulating diverse physiological processes and novel insights into understanding the mechanism of food habit transition in grass carp.
•Grass carp MC4R cDNA was cloned and was highly homologous to several teleost MC4Rs.•Grass carp mc4r was expressed highly in brain while slightly in peripheral tissues.•Grass carp MC4R showed higher basal cAMP production compared with hMC4R.•ACTH (1–24) showed higher affinity and potency for grass carp MC4R than human MC4R.