Familial Glucocorticoid Receptor Haploinsufficiency by NonSense Mediated mRNA Decay, Adrenal Hyperplasia and Apparent Mineralocorticoid Excess

Assistance Publique-Hôpitaux de Paris, Hôpital de Bicêtre, Service de Génétique Moléculaire, Pharmacogénétique et Hormonologie, Le Kremlin Bicêtre, France.
PLoS ONE (Impact Factor: 3.73). 01/2010; 5(10). DOI: 10.1371/journal.pone.0013563
Source: PubMed

ABSTRACT Primary glucocorticoid resistance (OMIM 138040) is a rare hereditary disease that causes a generalized partial insensitivity to glucocorticoid action, due to genetic alterations of the glucocorticoid receptor (GR). Investigation of adrenal incidentalomas led to the discovery of a family (eight affected individuals spanning three generations), prone to cortisol resistance, bilateral adrenal hyperplasia, arterial hypertension and hypokalemia. This phenotype exacerbated over time, cosegregates with the first heterozygous nonsense mutation p.R469[R,X] reported to date for the GR, replacing an arginine (CGA) by a stop (TGA) at amino-acid 469 in the second zinc finger of the DNA-binding domain of the receptor. In vitro, this mutation leads to a truncated 50-kDa GR lacking hormone and DNA binding capacity, devoid of hormone-dependent nuclear translocation and transactivation properties. In the proband's fibroblasts, we provided evidence for the lack of expression of the defective allele in vivo. The absence of detectable mutated GR mRNA was accompanied by a 50% reduction in wild type GR transcript and protein. This reduced GR expression leads to a significantly below-normal induction of glucocorticoid-induced target genes, FKBP5 in fibroblasts. We demonstrated that the molecular mechanisms of glucocorticoid signaling dysfunction involved GR haploinsufficiency due to the selective degradation of the mutated GR transcript through a nonsense-mediated mRNA Decay that was experimentally validated on emetine-treated propositus' fibroblasts. GR haploinsufficiency leads to hypertension due to illicit occupation of renal mineralocorticoid receptor by elevated cortisol rather than to increased mineralocorticoid production reported in primary glucocorticoid resistance. Indeed, apparent mineralocorticoid excess was demonstrated by a decrease in urinary tetrahydrocortisone-tetrahydrocortisol ratio in affected patients, revealing reduced glucocorticoid degradation by renal activity of the 11β-hydroxysteroid dehydrogenase type 2, a GR regulated gene. We propose thus that GR haploinsufficiency compromises glucocorticoid sensitivity and may represent a novel genetic cause of subclinical hypercortisolism, incidentally revealed bilateral adrenal hyperplasia and mineralocorticoid-independent hypertension.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Glucocorticoid (GC) sensitivity depends on glucocorticoid receptor (GR) and heat-shock proteins (Hsps). We investigated whether common GR gene (ER22/23EK, N363S, BclI, 9β) and adrenocorticotropin receptor promoter polymorphisms influence susceptibility for unilateral adrenal incidentaloma (AI), plus GR and Hsps expression in tumorous (n=19), peritumorous (n=13) and normal adrenocortical (n=11) tissues. Patients (n=112), population-matched controls (n=100), and tumor tissues (n=32) were genotyped for these polymorphisms. Post-dexamethasone serum cortisol was higher in patients (p<0.001). GR gene variants, larger allele of BclI [odds ratio (OR)=2.9; 95% confidence interval (CI): 1.7-5.1; p<0.001] and minor allele of 9β (OR=3.0; 95% CI: 1.6-5.7; p<0.001) were independent predictors of AI. In patients, the first allele is linked with larger tumors (p=0.002) and the latter with higher post-dexamethasone cortisol levels (p=0.025). Both allele carriers had lesser waist circumference (p=0.02), similar adrenocorticotropin, higher basal (p=0.024) and post-dexamethasone cortisol concentrations (p<0.001). Tumorous and constitutional genotypes were similar. GR-D is the major receptor isoform in normal adrenal cortex by Western-blotting. Loss of other receptor isoforms, decrease in immunostaining for GR (p<0.001), underexpression of chaperones (p≤0.01) and the presence of inducible Hsp70 were found in adenomas. In conclusion, GR gene variants, C allele of BclI and minor allele of 9β, are associated with AIs. Their concurrent presence in patients reduces GC sensitivity. Normal adrenal cortex preferentially expresses GR-D. In adenomas, the lack of other GR isoforms and underexpression of Hsps perhaps permanently impair GC signalling, which could promote dysregulated cortisol production and the tumor growth. The innate GC sensitivity probably modifies these effects.
    Molecular Medicine 11/2012; · 4.47 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Glucocorticoids are vital for the structural and functional maturation of fetal organs, yet excessive fetal exposure is detrimental to adult cardiovascular health. To elucidate the role of glucocorticoid signalling in late gestation cardiovascular maturation, we have generated mice with conditional disruption of glucocorticoid receptor (GR) in cardiomyocytes and vascular smooth muscle cells using smooth muscle protein 22-driven Cre recombinase (SMGRKO mice) and compared them to mice with global deficiency in GR (GR(-/-)). Echocardiography shows impaired heart function in both SMGRKO and GR(-/-) mice at embryonic day (E)17.5, associated with generalised edema. Cardiac ultrastructure is markedly disrupted in both SMGRKO and GR(-/-) mice at E17.5, with short, disorganised myofibrils and cardiomyocytes that fail to align in the compact myocardium. Failure to induce critical genes involved in contractile function, calcium handling and energy metabolism underpins this common phenotype. However, although hearts of GR(-/-) mice are smaller, with 22% reduced ventricular volume at E17.5, SMGRKO hearts are normally sized. Moreover, whilst levels of mRNA encoding atrial natriuretic peptide are reduced in E17.5 GR(-/-) hearts, they are normal in fetal SMGRKO hearts. These data demonstrate that structural, functional and biochemical maturation of the fetal heart is dependent on glucocorticoid signalling within cardiomyocytes and vascular smooth muscle, though some aspects of heart maturation (size, ANP expression) are independent of GR at these key sites.
    Human Molecular Genetics 04/2013; · 7.69 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Normosmic congenital hypogonadotropic hypogonadism (nCHH) is a rare reproductive disease leading to lack of puberty and infertility. Loss-of-function mutations of GNRH1 gene are a very rare cause of autosomal recessive nCHH. R31C GNRH1 is the only missense mutation that affects the conserved GnRH decapeptide sequence. This mutation was identified in a CpG islet in nine nCHH subjects from four unrelated families, giving evidence for a putative "hot spot". Interestingly, all the nCHH patients carry this mutation in heterozygosis that strikingly contrasts with the recessive inheritance associated with frame shift and non-sense mutations. Therefore, after exclusion of a second genetic event, a comprehensive functional characterization of the mutant R31C GnRH was undertaken. Using different cellular models, we clearly demonstrate a dramatic reduction of the mutant decapeptide capacity to bind GnRH-receptor, to activate MAPK pathway and to trigger inositol phosphate accumulation and intracellular calcium mobilization. In addition it is less able than wild type to induce lh-beta transcription and LH secretion in gonadotrope cells. Finally, the absence of a negative dominance in vitro offers a unique opportunity to discuss the complex in vivo patho-physiology of this form of nCHH.
    PLoS ONE 01/2013; 8(7):e69616. · 3.73 Impact Factor

Full-text (2 Sources)

Available from
May 21, 2014