Third Institute of Oceanography, SOA, Xiamen, 361005, China.
Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA.
Sci Rep. 2017 Jul 18;7(1):5684. doi: 10.1038/s41598-017-05962-1.
Cetaceans, a group of mammals adapted to the aquatic environment that descended from terrestrial artiodactyls, exhibit tremendous interspecific differences in a number of phenotypes, including feeding behavior, such as filter feeding in the Mysticeti vs prey-hunting Odontoceti, and size, with the smallest cetacean, the vaquita, at 1.4 meters and the largest, the blue whale, reaching 33 meters. The Melanocortin-4 receptor (MC4R) regulates food intake, energy balance, and somatic growth in both mammals and teleosts. In this study, we examined allelic variants of the MC4R in cetaceans. We sequenced the MC4R from 20 cetaceans, and pharmacologically characterized 17 of these protein products. Results identified a single variation at amino acid 156 in the MC4R from representative species of major cetacean lineages uniquely associated with the toothed whales or Odontoceti (arginine at 156) and baleen whales or Mysticeti (glutamine at 156). The Q156 receptor variant found in the larger baleen whales was functionally less responsive to its endogenous anorexigenic ligand, α-MSH. Furthermore, the R156 receptor variant showed greater constitutive activity and a higher affinity for ligand. These data suggest that the MC4R may be one gene involved in the evolution of feeding ecology, energy balance, and body size in cetaceans.
鲸类动物是一组适应水生环境的哺乳动物，它们起源于陆生偶蹄目动物，在许多表型上表现出巨大的种间差异，包括进食行为，如须鲸的滤食与齿鲸的捕食猎物行为，以及体型大小，最小的鲸类动物是小头鼠海豚，体长 1.4 米，最大的是蓝鲸，体长 33 米。黑素皮质素受体 4（MC4R）在哺乳动物和硬骨鱼中调节食物摄入、能量平衡和身体生长。在这项研究中，我们研究了鲸类动物中 MC4R 的等位基因变异。我们从 20 种鲸类动物中测序了 MC4R，并对其中的 17 种蛋白质产物进行了药理学表征。结果在来自主要鲸类动物谱系代表物种的 MC4R 中发现了一个单一的氨基酸 156 处的变异，该变异与有齿鲸或齿鲸（156 位的精氨酸）和须鲸或须鲸（156 位的谷氨酰胺）独特相关。在较大的须鲸中发现的 Q156 受体变异对其内源性厌食配体 α-MSH 的反应性较低。此外，R156 受体变异显示出更高的组成活性和对配体的更高亲和力。这些数据表明，MC4R 可能是参与鲸类动物进食生态、能量平衡和体型进化的一个基因。
