title: Molecular cloning, tissue distribution, and pharmacological characterization of melanocortin-4 receptor in spotted scat, Scatophagus argus.
abstract: Melanocortin-4 receptor (MC4R) plays an important role in the regulation of food intake and energy expenditure in mammals. The functions of the MC4R in fish have not been investigated extensively. We herein reported on the cloning, tissue distribution, and pharmacological characterization of spotted scat (Scatophagus argus) MC4R (SAMC4R). It consisted of a 984bp open reading frame predicted to encode a protein of 327 amino acids. Sequence analysis revealed that SAMC4R was highly homologous (>80%) at amino acid levels to several teleost MC4Rs. Phylogenetic analyses showed that SAMC4R was closely related to piscine MC4R. Using RT-PCR, we showed that in addition to brain, pituitary, and gonads, mc4r mRNA was also widely expressed in peripheral tissues of spotted scat in sexually divergent pattern. With human MC4R (hMC4R) as a control, several agonists including α-melanocyte stimulating hormone (α-MSH), [Nle(4), D-Phe(7)]-α-MSH (NDP-MSH), adrenocorticotropic hormone (ACTH) and THIQ (N-[(3R)-1,2,3,4-tetrahydroisoquinolinium3-ylcarbonyl]-(1R)-1-(4-chlorobenzyl)-2-[4-cyclohexyl-4-(1H-1,2,4-triazol-1-ylmethyl)piperidin-1-yl]-2-oxoethylamine), were used to investigate the binding and signaling properties of SAMC4R. The results showed that SAMC4R bound NDP-MSH with the highest affinity followed by ACTH (1-24) and α-MSH. Similar ranking was also found for hMC4R, although SAMC4R had two to five-fold higher affinities for these ligands. THIQ did not displace NDP-MSH from SAMC4R, different from hMC4R. α-MSH, NDP-MSH, and ACTH (1-24) were identified as potent agonists to stimulate cAMP generation followed by THIQ in SAMC4R. The availability of SAMC4R and its pharmacological characteristics will facilitate the investigation of its function in regulating diverse physiological processes in spotted scat.
authors.affiliation: Fisheries College, Guangdong Ocean University, Zhanjiang 524088, China; Key Laboratory of Aquaculture in South China Sea for Aquatic Economic Animal of Guangdong Higher Education Institutes, Guangdong Ocean University, Zhanjiang 524088, China.
authors.forename: Jian-Tao
authors.initials: JT
authors.lastname: Li
authors.affiliation: Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States.
authors.forename: Zhao
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Fisheries College, Guangdong Ocean University, Zhanjiang 524088, China; Key Laboratory of Aquaculture in South China Sea for Aquatic Economic Animal of Guangdong Higher Education Institutes, Guangdong Ocean University, Zhanjiang 524088, China.
authors.forename: Hua-Pu
authors.initials: HP
authors.lastname: Chen
authors.affiliation: Fisheries College, Guangdong Ocean University, Zhanjiang 524088, China; Key Laboratory of Aquaculture in South China Sea for Aquatic Economic Animal of Guangdong Higher Education Institutes, Guangdong Ocean University, Zhanjiang 524088, China.
authors.forename: Chun-Hua
authors.initials: CH
authors.lastname: Zhu
authors.affiliation: Fisheries College, Guangdong Ocean University, Zhanjiang 524088, China; Key Laboratory of Aquaculture in South China Sea for Aquatic Economic Animal of Guangdong Higher Education Institutes, Guangdong Ocean University, Zhanjiang 524088, China.
authors.forename: Si-Ping
authors.initials: SP
authors.lastname: Deng
authors.affiliation: Fisheries College, Guangdong Ocean University, Zhanjiang 524088, China; Key Laboratory of Aquaculture in South China Sea for Aquatic Economic Animal of Guangdong Higher Education Institutes, Guangdong Ocean University, Zhanjiang 524088, China. Electronic address: guangli211@163.com.
authors.forename: Guang-Li
authors.initials: GL
authors.lastname: Li
authors.affiliation: Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States. Electronic address: taoyaxi@auburn.edu.
authors.forename: Ya-Xiong
authors.initials: YX
authors.lastname: Tao
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D005260:Female; D057809:HEK293 Cells; D006801:Humans; D008024:Ligands; D008297:Male; D010473:Perciformes / Q000235:genetics* / Q000378:metabolism*; D010802:Phylogeny; D044105:Receptor, Melanocortin, Type 4 / Q000235:genetics* / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D014018:Tissue Distribution; D000521:alpha-MSH / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D008024:Ligands; D044105:Receptor, Melanocortin, Type 4; D000521:alpha-MSH; C027756:MSH, 4-Nle-7-Phe-alpha-; D000324:Adrenocorticotropic Hormone
keywords: Ligand binding; Melanocortin-4 receptor; Signaling; Spotted scat; Tissue distribution