A mutation of the glucocorticoid receptor in primary cortisol resistance.

Abstract

The precise molecular abnormalities that cause primary cortisol resistance have not been completely described. In a subject with primary cortisol resistance we have observed glucocorticoid receptors (hGR) with a decreased affinity for dexamethasone. We hypothesize that a mutation of the hGR glucocorticoid-binding domain is the cause of cortisol resistance. Total RNA isolated from the index subject's mononuclear leukocytes was used to produce first strand hGR cDNAs, and the entire hGR cDNA was amplified in segments and sequenced. At nucleotide 2,317 we identified a homozygous A for G point mutation that predicts an isoleucine (ATT) for valine (GT1) substitution at amino acid 729. When the wild-type hGR and hGR-Ile 729 were expressed in COS-1 cells and assayed for 13H1-Dexamathasone binding, the dissociation constants were 0.799±0.068 and 1.54±0.06 nM (mean±SEM) (P < 0.01), respectively. When the wild-type hGR and hGR-Ile 729 were expressed in CV-1 cells that were cotransfected with the mouse mammary tumor virus long terminal repeat fused to the chloramphenicol acetyl transferase (CAT) gene, the hGR-Ile 729 conferred a fourfold decrease in apparent potency on dexamethasone stimulation of CAT activity. The isoleucine for valine substitution at amino acid 729 impairs the function of the hGR and is the likely cause of primary cortisol resistance in this subject. (J. Clin. Invest. 1993.91:1918-1925

Glucocorticoid and mineralocorticoid resistance/hypersensitivity syndromes

“…Since then, over ten kindreds and sporadic cases have been reported (Iida et al 1985, Lamberts et al 1986, 1992, Nawata et al 1987, Vecsei et al 1989, Hurley et al 1991, Karl et al 1993, 1996, Malchoff et al 1993. Abnormalities of the GR number, affinity for glucocorticoids, stability and translocation into the nucleus have been described.…”

“…This resulted in complete ablation of one of the GR alleles in affected members of the family (Karl et al 1993). The propositus of the third kindred had a single homozygotic point mutation at amino acid 729 (valine to isoleucine) in the hormone-binding domain, which reduced both the affinity and transactivation activity of the GR (Malchoff et al 1993). There was also an interesting sporadic case of a man with a de novo, germ-line, heterozygotic GR mutation at amino acid 559 (isoleucin to asparagine) in the hormone-binding domain, at the hinge region, proximal to the DNA-binding domain.…”

A Polymorphism in the Glucocorticoid Receptor Gene, Which Decreases Sensitivity to Glucocorticoids In Vivo, Is Associated With Low Insulin and Cholesterol Levels

“…The molecular mechanisms underlying this variation in GC sensitivity are still largely unknown. In the symptomatic patients with familial forms of GC resistance, missense mutations in the ligand binding domain of the GR gene, causing decreased ligand binding affinity, have been described (6,7), as well as a deletion of four base pairs at the boundary of exon 6 and intron 6, causing loss of a splice site and a 50% reduction of receptor numbers per cell, resulting also in GC resistance (8). Within the normal population, several polymorphisms in the GR gene have been reported (9).…”

Genetic Variations in the Glucocorticoid Receptor Gene Are Not Related to Glucocorticoid Resistance in Childhood Acute Lymphoblastic Leukemia

“…1A and B; refs. [6][7][8][9][10]. Besides somatic mutations, polymorphisms within the GR gene have been described in healthy populations ( Table 1), of which some were associated with altered responsiveness to glucocorticoid.…”