Background Generalized glucocorticoid resistance syndrome is a rare familial or sporadic condition characterized by generalized, partial, target-tissue insensitivity to glucocorticoids. This syndrome is partially caus...Background Generalized glucocorticoid resistance syndrome is a rare familial or sporadic condition characterized by generalized, partial, target-tissue insensitivity to glucocorticoids. This syndrome is partially caused by mutations in human glucocorticoid receptor （hGR） gene. The clinical spectrum of generalized glucocorticoid resistance is broad, ranging from fatigue or no symptoms to severe hypertension with hypokalemic alkalosis. The purpose of this study was to explore the genetic disorder of glucocorticoid resistance syndrome.Methods We identified a 56-year-old male patient diagnosed with generalized glucocorticoid resistance syndrome accompanied with an adrenocortical adenoma. This asymptomatic patient referred to Peking Union Medical College Hospital for treatment of his adrenal incidentaloma. Endocrinological evaluation consistently revealed his elevated serum cortisol level. Total RNA was extracted from the patient＇s peripheral blood mononuclear leukocytes （PBMLs） and entire coding region of hGR alpha was amplified by reverse transcription （RT）-PCR. To confirm the possible mutation identified by sequencing RT-PCR products, genomic DNA sequence of hGR gene from the patient and 50 healthy controls was analyzed by PCR and directly sequencing.Results A heterozygotic （C→T） substitution at nucleotide position of 1667 （exon 5） in GR alpha gene was found in this patient by sequencing of RT-PCR products of hGR gene. This substitution was also identified at genomic DNA level and it was absent in 100 chromosomes from 50 unrelated health controls. This substitution resulted in a threonine to isoleucine substitution （ACT→ATT） at amino acid 556 in the ligand-binding domain of GR alpha. Conclusion Generalized glucocorticoid resistance in this patient might be caused by a novel heterozygotic mutation in the ligand-binding domain of the GR alpha.展开更多
Pregnane X receptor(PXR)is the major regulator of xenobiotic metabolism.PXR itself is controlled by various signaling molecules including glucocorticoids.Moreover,negative feed-back regulation has been proposed at the...Pregnane X receptor(PXR)is the major regulator of xenobiotic metabolism.PXR itself is controlled by various signaling molecules including glucocorticoids.Moreover,negative feed-back regulation has been proposed at the transcriptional level.We examined the involvement of the 3’-untranslated region(3’-UTR)of NR1I2 mRNA and microRNAs in PXR-and glucocorticoid receptor(GR)-mediated regulation of NR1I2 gene expression.PXR ligands were found to significantly downregulate NR1I2 mRNA expression in a set of 14 human hepatocyte cultures.Similarly,PXR was downregulated by PCN in the C57/BL6 mice liver.In mechanistic studies with the full-length 3’-UTR cloned into luciferase reporter or expression vectors,we showed that the 3’-UTR reduces PXR expression.From the miRNAs tested,miR-18a-5p inhibited both NR 112 expression and CYP3A4 gene induction.Importantly,we observed significant upregulation of miR-18a-5p expression 6 h after treatment with the PXR ligand rifampicin,which indicates a putative mechanism underlying NR1I2 negative feed-back regulation in hepatic cells.Additionally,glucocorticoids upregulated NR1I2 expression not only through the promoter region but also via 3’-UTR regulation,which likely involves downregulation of miR-18a-5p.We conclude that miR-18a-5p is involved in the down-regulation of NR1I2expression by its ligands and in the upregulation of NR1I2 mRNA expression by glucocorticoids in hepatic cells.展开更多
文摘Background Generalized glucocorticoid resistance syndrome is a rare familial or sporadic condition characterized by generalized, partial, target-tissue insensitivity to glucocorticoids. This syndrome is partially caused by mutations in human glucocorticoid receptor （hGR） gene. The clinical spectrum of generalized glucocorticoid resistance is broad, ranging from fatigue or no symptoms to severe hypertension with hypokalemic alkalosis. The purpose of this study was to explore the genetic disorder of glucocorticoid resistance syndrome.Methods We identified a 56-year-old male patient diagnosed with generalized glucocorticoid resistance syndrome accompanied with an adrenocortical adenoma. This asymptomatic patient referred to Peking Union Medical College Hospital for treatment of his adrenal incidentaloma. Endocrinological evaluation consistently revealed his elevated serum cortisol level. Total RNA was extracted from the patient＇s peripheral blood mononuclear leukocytes （PBMLs） and entire coding region of hGR alpha was amplified by reverse transcription （RT）-PCR. To confirm the possible mutation identified by sequencing RT-PCR products, genomic DNA sequence of hGR gene from the patient and 50 healthy controls was analyzed by PCR and directly sequencing.Results A heterozygotic （C→T） substitution at nucleotide position of 1667 （exon 5） in GR alpha gene was found in this patient by sequencing of RT-PCR products of hGR gene. This substitution was also identified at genomic DNA level and it was absent in 100 chromosomes from 50 unrelated health controls. This substitution resulted in a threonine to isoleucine substitution （ACT→ATT） at amino acid 556 in the ligand-binding domain of GR alpha. Conclusion Generalized glucocorticoid resistance in this patient might be caused by a novel heterozygotic mutation in the ligand-binding domain of the GR alpha.
基金supported by grants from the Czech Science Foundation 17-06841S to Petr PavekEFSA-CDN(No.CZ.02.1.01/0.0/0.0/16_019/0000841,Czech Republic)co-funded by ERDF to Tomas Smutny.
文摘Pregnane X receptor(PXR)is the major regulator of xenobiotic metabolism.PXR itself is controlled by various signaling molecules including glucocorticoids.Moreover,negative feed-back regulation has been proposed at the transcriptional level.We examined the involvement of the 3’-untranslated region(3’-UTR)of NR1I2 mRNA and microRNAs in PXR-and glucocorticoid receptor(GR)-mediated regulation of NR1I2 gene expression.PXR ligands were found to significantly downregulate NR1I2 mRNA expression in a set of 14 human hepatocyte cultures.Similarly,PXR was downregulated by PCN in the C57/BL6 mice liver.In mechanistic studies with the full-length 3’-UTR cloned into luciferase reporter or expression vectors,we showed that the 3’-UTR reduces PXR expression.From the miRNAs tested,miR-18a-5p inhibited both NR 112 expression and CYP3A4 gene induction.Importantly,we observed significant upregulation of miR-18a-5p expression 6 h after treatment with the PXR ligand rifampicin,which indicates a putative mechanism underlying NR1I2 negative feed-back regulation in hepatic cells.Additionally,glucocorticoids upregulated NR1I2 expression not only through the promoter region but also via 3’-UTR regulation,which likely involves downregulation of miR-18a-5p.We conclude that miR-18a-5p is involved in the down-regulation of NR1I2expression by its ligands and in the upregulation of NR1I2 mRNA expression by glucocorticoids in hepatic cells.
