Cai X, Mipam T D, Zhao F F, Sun L
1School of Life Science and Engineering,Southwest University of Science and Technology,Mianyang 621010,China.
2College of Life Science and Technology,Southwest University for Nationalities,Chengdu 610041,China.
Animal. 2015 Jul;9(7):1097-103. doi: 10.1017/S1751731115000397. Epub 2015 Mar 11.
MC4R (melanocortin 4 receptor) is expressed in the appetite-regulating areas of the brain and takes part in leptin signaling pathways. Sequencing of the coding region of the MC4R gene for 354 yaks identified the following five single nucleotide polymorphisms (SNPs): SNP1 (273C>T), SNP2 (321 G>T), SNP3 (864 C>A), SNP4 (1069G>C) and SNP5 (1206 G>C). SNP1, SNP2 and SNP3 were synonymous mutations, whereas SNP4 and SNP5 were missense mutations resulting in amino acid substitutions (V286L and R331S). Pairwise linkage disequilibrium (LD) analysis indicated that two pairs of SNPs, SNP2 and SNP5 (r(2)=0.81027) and SNP4 and SNP5 (r(2)=0.53816), exhibited higher degrees of LD. CC genotype of SNP4, CGACG and CTCCC haplotypes for all SNPs were associated with increased BW of animals that were 18 months old and with the average daily gain. The secondary structure and transmembrane region prediction of the yak MC4R protein suggested that SNP4 was correlated with influential changes in the seventh transmembrane domain of the MC4R protein and with the functional deterioration or even incapacitation of MC4R, which may contribute to the increased feed intake, BW and average daily gain of the yaks with CC genotypes. The data from this study suggested that 1069G>C SNP of the MC4R gene could be used in marker-assisted selection of growth traits in the Maiwa yak breed.
黑皮质素4受体（MC4R）在大脑的食欲调节区域表达，并参与瘦素信号通路。对354头牦牛的MC4R基因编码区进行测序，鉴定出以下五个单核苷酸多态性（SNP）：SNP1（273C>T）、SNP2（321G>T）、SNP3（864C>A）、SNP4（1069G>C）和SNP5（1206G>C）。SNP1、SNP2和SNP3是同义突变，而SNP4和SNP5是错义突变，导致氨基酸替换（V286L和R331S）。成对连锁不平衡（LD）分析表明，两对SNP，即SNP2和SNP5（r(2)=0.81027）以及SNP4和SNP5（r(2)=0.53816），表现出较高程度的LD。SNP4的CC基因型、所有SNP的CGACG和CTCCC单倍型与18月龄动物的体重增加以及平均日增重相关。牦牛MC4R蛋白的二级结构和跨膜区域预测表明，SNP4与MC4R蛋白第七跨膜结构域的显著变化以及MC4R的功能恶化甚至丧失有关，这可能导致CC基因型牦牛的采食量、体重和平均日增重增加。本研究数据表明，MC4R基因的1069G>C SNP可用于麦洼牦牛品种生长性状的标记辅助选择。
