Research Unit Molecular Biology, Leibniz Institute for Farm Animal Biology (FBN), Dummerstorf, Germany.
PLoS One. 2012;7(9):e45518. doi: 10.1371/journal.pone.0045518. Epub 2012 Sep 18.
Glucocorticoids produced in the adrenal cortex under the control of the hypothalamic-pituitary axis play a vital role in the maintenance of basal and stress-related homeostasis and influence health and well-being. To identify loci affecting regulation of the hypothalamic-pituitary-adrenal (HPA) axis in the pig we performed a genome-wide association study for two parameters of acute and long-term adrenal activity: plasma cortisol level and adrenal weight. We detected a major quantitative trait locus at the position of the glucocorticoid receptor gene (NR3C1) - a key regulator of HPA axis activity. To determine the causal variant(s), we resequenced the coding region of NR3C1 and found three missense single nucleotide polymorphisms (SNPs). SNP c.1829C>T, leading to a p.Ala610Val substitution in the ligand binding domain, showed large (about 0.6× and 1.2× phenotypic standard deviations for cortisol level and adrenal weight, respectively), and highly significant (2.1E-39≤log10(1/p)≤1.7E+0) negative effects on both traits. We were able to replicate the association in three commercial pig populations with different breed origins. We analyzed effects of the p.Ala610Val substitution on glucocorticoid-induced transcriptional activity of porcine glucocorticoid receptor (GR) in vitro and determined that the substitution introduced by SNP c.1829C>T increased sensitivity of GR by about two-fold. Finally, we found that non-coding polymorphisms in linkage disequilibrium with SNP c.1829C>T have only a minor effect on the expression of NR3C1 in tissues related to the HPA axis. Our findings provide compelling evidence that SNP c.1829C>T in porcine NR3C1 is a gain-of-function mutation with a major effect on the activity of the adrenal gland. Pigs carrying this SNP could provide a new animal model to study neurobiological and physiological consequences of genetically based GR hypersensitivity and adrenal hypofunction.
肾上腺皮质在下丘脑-垂体轴的控制下产生的糖皮质激素在维持基础和应激相关的体内平衡方面发挥着至关重要的作用，并影响着健康和幸福。为了确定影响猪下丘脑-垂体-肾上腺（HPA）轴调节的基因座，我们对两个急性和长期肾上腺活性参数进行了全基因组关联研究：血浆皮质醇水平和肾上腺重量。我们在糖皮质激素受体基因（NR3C1）的位置检测到一个主要的数量性状基因座 - HPA 轴活性的关键调节剂。为了确定因果变异，我们对 NR3C1 的编码区进行了重测序，发现了三个错义单核苷酸多态性（SNP）。SNP c.1829C>T 导致配体结合域中的 p.Ala610Val 取代，对皮质醇水平和肾上腺重量的表型标准差分别有较大（约 0.6×和 1.2×）和高度显著（2.1E-39≤log10(1/p)≤1.7E+0）的负向影响。我们能够在三个具有不同起源的商业猪群中复制这种关联。我们分析了 SNP c.1829C>T 对体外猪糖皮质激素受体（GR）的糖皮质激素诱导转录活性的影响，并确定该取代通过 SNP c.1829C>T 引入，使 GR 的敏感性增加了约两倍。最后，我们发现与 SNP c.1829C>T 连锁不平衡的非编码多态性对与 HPA 轴相关组织中 NR3C1 的表达只有很小的影响。我们的研究结果提供了令人信服的证据，表明猪 NR3C1 中的 SNP c.1829C>T 是一个具有主要功能的获得性功能突变，对肾上腺的活性有重大影响。携带这种 SNP 的猪可能为研究基于遗传的 GR 超敏性和肾上腺功能减退的神经生物学和生理学后果提供一个新的动物模型。
