title: A substitution in the ligand binding domain of the porcine glucocorticoid receptor affects activity of the adrenal gland.
abstract: 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.
authors.affiliation: Research Unit Molecular Biology, Leibniz Institute for Farm Animal Biology (FBN), Dummerstorf, Germany.
authors.forename: Eduard
authors.initials: E
authors.lastname: Murani
authors.forename: Henry
authors.initials: H
authors.lastname: Reyer
authors.forename: Siriluck
authors.initials: S
authors.lastname: Ponsuksili
authors.forename: Stephan
authors.initials: S
authors.lastname: Fritschka
authors.forename: Klaus
authors.initials: K
authors.lastname: Wimmers
mesh_terms: D000311:Adrenal Glands / Q000033:anatomy & histology / Q000378:metabolism*; D000483:Alleles; D017398:Alternative Splicing; D019943:Amino Acid Substitution; D000818:Animals; D055106:Genome-Wide Association Study; D006854:Hydrocortisone / Q000097:blood; D008024:Ligands; D020125:Mutation, Missense; D016366:Open Reading Frames; D009929:Organ Size; D020641:Polymorphism, Single Nucleotide; D054730:Protein Interaction Domains and Motifs / Q000235:genetics*; D040641:Quantitative Trait Loci; D059368:RNA Isoforms; D011965:Receptors, Glucocorticoid / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D013552:Swine
chemical_list: D008024:Ligands; D059368:RNA Isoforms; D011965:Receptors, Glucocorticoid; D006854:Hydrocortisone