Bai Y, Zhang J B, Xue Y, Peng Y L, Chen G, Fang M Y
Department of Animal Genetics and Breeding, National Engineering Laboratory for Animal Breeding, MOA Laboratory of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China; College of Agriculture, Hebei University of Engineering, Handan, 056021, China.
Anim Genet. 2015 Feb;46(1):16-22. doi: 10.1111/age.12257. Epub 2014 Dec 16.
Cytochrome b5 (CYB5A) is an important electron transfer protein with homologues in a number of different organisms. In pigs, CYB5A is related to boar taint because of its role in androstenone biosynthesis. To determine the variety of CYB5A expression in pig breeds, genetic variations in the porcine CYB5A promoter region in both Chinese and European pig breeds were examined. Three single nucleotide polymorphisms (NC_010443.4:g.165901487delG, g.165901767T>C and g.165902078C>T) were identified in the porcine CYB5A promoter region. These SNPs occurred in different frequencies in Chinese and European pigs. Chinese pigs were primarily haplotype B (denoted as delG-C-T: the position of nt 165901487 of the CYB5 gene is a G deletion, nt 165901767 is C and nt 165902078 is T), except for Licha black pigs, which were primarily haplotype A (denoted as G-T-C: nt 165901487 is G, nt 165901767 is T and nt 165902078 is C), similar to European pigs. Quantitative PCR data from liver tissues demonstrated that haplotype B individuals had higher CYB5A expression than did those with haplotype A. This was confirmed by in vitro cell transfection assays, in which haplotype B individuals had higher reporter activity than did those with haplotype A. In silico analysis predicted that Myc-associated zinc-finger protein (MAZ) is a potential transcription factor at position 165901767. Electrophoretic mobility shift assays showed this polymorphism affects the stable binding of transcription factors to the CYB5A promoter, which in turn affects the expression levels of this gene. Therefore, this variation of the porcine CYB5A promoter region may explain the differences in androstenone accumulation between Chinese and European pig breeds and may also prove useful as a genetic marker to distinguish the origin of different pig breeds.
细胞色素b5（CYB5A）是一种重要的电子传递蛋白，在许多不同生物中都有同源物。在猪中，CYB5A与公猪异味有关，因为它在雄烯酮生物合成中起作用。为了确定猪品种中CYB5A表达的差异，研究了中国和欧洲猪品种中猪CYB5A启动子区域的遗传变异。在猪CYB5A启动子区域鉴定出三个单核苷酸多态性（NC_010443.4:g.165901487delG、g.165901767T>C和g.165902078C>T）。这些单核苷酸多态性在中国猪和欧洲猪中的出现频率不同。中国猪主要是单倍型B（表示为delG-C-T：CYB5基因第165901487位核苷酸是G缺失，第165901767位是C，第165902078位是T），但利岔黑猪除外，其主要是单倍型A（表示为G-T-C：第165901487位是G，第165901767位是T，第165902078位是C），与欧洲猪相似。肝脏组织的定量PCR数据表明，单倍型B个体的CYB5A表达高于单倍型A个体。体外细胞转染试验证实了这一点，其中单倍型B个体的报告基因活性高于单倍型A个体。计算机分析预测，Myc相关锌指蛋白（MAZ）是第165901767位的潜在转录因子。电泳迁移率变动分析表明，这种多态性影响转录因子与CYB5A启动子的稳定结合，进而影响该基因的表达水平。因此，猪CYB5A启动子区域的这种变异可能解释了中国和欧洲猪品种之间雄烯酮积累的差异，也可能作为区分不同猪品种起源的遗传标记。
