Department of Horse Breeding, Poznan University of Life Sciences, Wolynska 33, 60-637, Poznan, Poland.
Department of Genetics and Animal Breeding, Poznan University of Life Sciences, Wolynska 33, 60-637, Poznan, Poland.
J Appl Genet. 2019 Feb;60(1):71-78. doi: 10.1007/s13353-018-0473-2. Epub 2018 Oct 16.
Genes encoding casein proteins are important candidates for milk composition traits in mammals. In the case of the domestic horse, our knowledge of casein genes is limited mainly to coding sequence variants. This study involved screening for polymorphism in 5'-flanking regions of four genes encoding equine caseins (CSN1S1, CSN1S2, CSN2, and CSN3) and making a preliminary assessment of their effect on the gene expression (on the mRNA and protein levels) and milk composition traits in selected horse breeds. Altogether, 23 polymorphisms (21 described previously SNPs and two novel InDels) were found in the studied sequences, the majority of which are common in various horse breeds. Statistical analysis revealed that some are putatively associated with gene expression or milk composition - for example, the c.-2047_-2048insAT polymorphism (CSN1S1) turns out to be related to the total milk protein content in Polish Primitive Horse (p < 0.05), whereas c.-2105C>G SNP (CSN2) is related to beta-casein relative mRNA level and milk lactose concentration in the Polish Coldblood Horse breed (p < 0.05). We have also found significant effects of horse breed and lactation time-point on gene expression and mare's milk composition. Our study indicates that the 5'-regulatory regions of genes encoding casein proteins are interesting targets for functional studies of their expression and the composition traits of mare's milk.
编码酪蛋白的基因是哺乳动物乳成分特征的重要候选基因。就家马而言，我们对酪蛋白基因的了解主要局限于编码序列变异。本研究涉及对编码马酪蛋白的四个基因（CSN1S1、CSN1S2、CSN2 和 CSN3）的 5' 侧翼区进行多态性筛选，并初步评估其对所选马品种基因表达（mRNA 和蛋白质水平）和乳成分特征的影响。在研究的序列中总共发现了 23 种多态性（21 种先前描述的 SNP 和两种新的 InDels），其中大多数在各种马品种中都很常见。统计分析表明，其中一些与基因表达或乳成分有关，例如，c.-2047_-2048insAT 多态性（CSN1S1）与波兰原始马的总乳蛋白含量有关（p<0.05），而 c.-2105C>G SNP（CSN2）与波兰冷血马品种的β-酪蛋白相对 mRNA 水平和乳乳糖浓度有关（p<0.05）。我们还发现了马品种和泌乳时间点对基因表达和母马乳汁成分的显著影响。我们的研究表明，编码酪蛋白的基因 5' 调控区是其表达和母马乳汁成分功能研究的有趣靶点。
