School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland.
BMC Genet. 2012 Jul 25;13:66. doi: 10.1186/1471-2156-13-66.
The PRKAG3 gene encodes the γ3 subunit of adenosine monophosphate activated protein kinase (AMPK), a protein that plays a key role in energy metabolism in skeletal muscle. Non-synonymous single nucleotide polymorphisms (SNPs) in this gene such as I199V are associated with important pork quality traits. The objective of this study was to investigate the relationship between gene expression of the PRKAG3 gene, SNP variation in the PRKAG3 promoter and meat quality phenotypes in pork.
PRKAG3 gene expression was found to correlate with a number of traits relating to glycolytic potential (GP) and intramuscular fat (IMF) in three phenotypically diverse F1 crosses comprising of 31 Large White, 23 Duroc and 32 Pietrain sire breeds. The majority of associations were observed in the Large White cross. There was a significant association between genotype at the g.-311A>G locus and PRKAG3 gene expression in the Large White cross. In the same population, ten novel SNPs were identified within a 1.3 kb region spanning the promoter and from this three major haplotypes were inferred. Two tagging SNPs (g.-995A>G and g.-311A>G) characterised the haplotypes within the promoter region being studied. These two SNPs were subsequently genotyped in larger populations consisting of Large White (n = 98), Duroc (n = 99) and Pietrain (n = 98) purebreds. Four major haplotypes including promoter SNP's g.-995A>G and g.-311A>G and I199V were inferred. In the Large White breed, HAP1 was associated with IMF% in the M. longissmus thoracis et lumborum (LTL) and driploss%. HAP2 was associated with IMFL% GP-influenced traits pH at 24 hr in LTL (pHULT), pH at 45 min in LTL (pH(45)LT) and pH at 45 min in the M. semimembranosus muscle (pH(45)SM). HAP3 was associated with driploss%, pHULT pH(45)LT and b* Minolta. In the Duroc breed, associations were observed between HAP1 and driploss% and pHUSM. No associations were observed with the remaining haplotypes (HAP2, HAP3 and HAP4) in the Duroc breed. The Pietrain breed was monomorphic in the promoter region. The I199V locus was associated with several GP-influenced traits across all three breeds and IMF% in the Large White and Pietrain breed. No significant difference in promoter function was observed for the three main promoter haplotypes when tested in vitro.
Gene expression levels of the porcine PRKAG3 are associated with meat quality phenotypes relating to glycolytic potential and IMF% in the Large White breed, while SNP variation in the promoter region of the gene is associated with PRKAG3 gene expression and meat quality phenotypes.
PRKAG3 基因编码腺苷一磷酸激活蛋白激酶（AMPK）的 γ3 亚基，该蛋白在骨骼肌能量代谢中发挥关键作用。该基因中的非同义单核苷酸多态性（SNP），如 I199V，与重要的猪肉质量性状有关。本研究的目的是研究 PRKAG3 基因的基因表达、PRKAG3 启动子中的 SNP 变异与猪肉质表型之间的关系。
在三个表型不同的 F1 杂交群体中，包括 31 头长白猪、23 头杜洛克猪和 32 头皮特兰猪，PRKAG3 基因的表达与与糖酵解潜力（GP）和肌内脂肪（IMF）相关的许多性状相关。大多数关联发生在长白猪杂交群体中。在长白猪杂交群体中，g.-311A>G 基因座的基因型与 PRKAG3 基因的表达存在显著相关性。在同一群体中，在包含启动子的 1.3kb 区域内鉴定出 10 个新的 SNP，并从中推断出三个主要单倍型。两个标记 SNP（g.-995A>G 和 g.-311A>G）描述了所研究启动子区域内的单倍型。这两个 SNP 随后在包括长白猪（n=98）、杜洛克猪（n=99）和皮特兰猪（n=98）在内的更大群体中进行了基因分型。推断出包括启动子 SNP g.-995A>G 和 g.-311A>G 以及 I199V 的四个主要单倍型。在长白猪品种中，HAP1 与背最长肌和腰大肌（LTL）中的 IMF%和滴水损失%相关。HAP2 与 LTL 中的 pH24 小时（pHULT）、LTL 中的 pH45 分钟（pH(45)LT）和半膜肌中的 pH45 分钟（pH(45)SM）相关。HAP3 与滴水损失%、pHULT pH(45)LT 和 Minolta b*值有关。在杜洛克猪品种中，观察到 HAP1 与滴水损失%和 pHUSM 之间存在关联。在杜洛克猪品种中，没有观察到其余单倍型（HAP2、HAP3 和 HAP4）的关联。皮特兰猪品种在启动子区域内是单态的。I199V 位点与三个品种的所有 GP 影响性状以及长白猪和皮特兰猪的 IMF%相关。当在体外进行测试时，三个主要启动子单倍型的启动子功能没有显著差异。
猪 PRKAG3 基因的表达水平与长白猪品种的糖酵解潜力和 IMF%相关的肉质表型有关，而基因启动子区域的 SNP 变异与 PRKAG3 基因的表达和肉质表型有关。
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