A NOVEL GLUCOCORTICOID RECEPTOR MUTATION IN PRIMARY GENERALIZED GLUCOCORTICOID RESISTANCE DISEASE

Objective: Primary generalized glucocorticoid resistance (PGGR) is a rare hereditary disease characterized by generalized partial target-tissue insensitivity to glucocorticoids. To date, few cases have been reported, and more cases, especially involving other races, are needed to fully understand this disease. Methods: This study presented a novel glucocorticoid receptor mutation in a PGGR pedigree. The index patient was a 14-year-old male with fatigue, hypokalemia, hypertension, and polyuria. Eleven family members were available for the genetic screen. Next-generation sequencing and Sanger sequencing were used to identify the mutation. We systematically investigated the molecular mechanism through which the mutation impaired glucocorticoid signal transduction in COS-7 cells. Results: The index patient carried a de novo homo-zygous mutation within exon 6 (c.1652C>A, p.551S>Y), whereas eight family members carrying a heterozygous mutation were all phenotypically silent. The affinity of the human glucocorticoid receptor (hGR) for the ligand was 1.97-fold lower in the patient than in the family members. Mutant hGRα (551Y) displayed a 3.2-fold reduction in its ability to transactivate glucocorticoid-responsive genes. When exposed to the same concentration of dexamethasone, hGRα (551Y) displayed a reduced ability to trans-locate into the nucleus and decreased levels of hGR dimer formation and could not effectively induce the glucocorticoid response element to regulate the transcription of related genes. After 2 years of dexamethasone treatment, the volume of the left and right adrenal glands of the index subject decreased by 55.6% and 32.4%, respectively. The pituitary volume decreased by 18.9%. During the 2-year follow-up, none of the heterozygous carriers developed hypertension or hypokalemia. Conclusion: We described a novel homozygous glucocorticoid receptor mutation causing PGGR. This homozygous mutation leads to hypertension and hypokalemia, but its heterozygous mutation has no relevant clinical symptoms. Abbreviations: ACTH = adrenocorticotropic hormone; DBD = DNA-binding domain; GR = glucocorticoid receptor; GRE = glucocorticoid response element; hGR = human glucocorticoid receptor; LBD = ligand-binding domain; PGGR = primary generalized glucocorticoid resistance

Dexamethasone suppresses JMJD3 gene activation via a putative negative glucocorticoid response element and maintains integrity of tight junctions in brain microvascular endothelial cells

The blood–brain barrier (BBB) exhibits a highly selective permeability to support the homeostasis of the central nervous system (CNS). The tight junctions in the BBB microvascular endothelial cells seal the paracellular space to prevent diffusion. Thus, disruption of tight junctions results in harmful effects in CNS diseases and injuries. It has recently been demonstrated that glucocorticoids have beneficial effects on maintaining tight junctions in both in vitro cell and in vivo animal models. In the present study, we found that dexamethasone suppresses the expression of JMJD3, a histone H3K27 demethylase, via the recruitment of glucocorticoid receptor α (GRα) and nuclear receptor co-repressor (N-CoR) to the negative glucocorticoid response element (nGRE) in the upstream region of JMJD3 gene in brain microvascular endothelial cells subjected to TNFα treatment. The decreased JMJD3 gene expression resulted in the suppression of MMP-2, MMP-3, and MMP-9 gene activation. Dexamethasone also activated the expression of the claudin 5 and occludin genes. Collectively, dexamethasone attenuated the disruption of the tight junctions in the brain microvascular endothelial cells subjected to TNFα treatment. Therefore, glucocorticoids may help to preserve the integrity of the tight junctions in the BBB via transcriptional and post-translational regulation following CNS diseases and injuries.