Project description:Primary aldosteronism (PA) is a common form of endocrine hypertension suspected in the presence of arterial hypertension (HT), hypokalemia and low plasma renin levels. While for a long time the genetic causes of PA have remained mysterious, recent findings have revealed an important role for an altered function of potassium channels in the pathogenesis of this disease. The basis for the unique sensitivity of adrenal zona glomerulosa (ZG) cells for plasma potassium concentration is a very high background potassium conductance, which is dependent on expression at high levels of two 2-pore domain (K2P) potassium channels, Task1 (KCNK3) and Task3 (KCNK9. Recent studies have shown that mice lacking Kcnk3 (Task1) or both Kcnk3 and Kcnk9 have PA. In Kcnk3 null mice, hyperaldosteronism is present in young animals of either sex, but is corrected in males after puberty. Strikingly, in these animals hyperaldosteronism associates with abnormal adrenal cortex functional zonation, since Cyp11b2, the rate-limiting enzyme for aldosterone production, is expressed in the inner region of the adrenal cortex and not in the glomerulosa. Additionally, this phenotype is under the control of sex hormones, as shown by the fact that castration of male Kcnk3 -/- animals prevents normal Cyp11b2 distribution, while testosterone injection in female Kcnk3 null mice restores expression of Cyp11b2 in ZG cells. We took advantage of the unique characteristics of the Kcnk3 null mouse model to search for genes that can modify their phenotype of PA and adrenocortical functional zonation. Using gene expression profiling in the adrenal glands of Kcnk3 null mice and exploiting the possibility of modulation of their phenotype by sexual hormones, we identified a cluster of genes closely associated with hyperaldosteronism in a sex- and hormone-dependent dynamic fashion. Among these genes, we focused our attention on Dkk3 (dickkopf3), encoding a peculiar member of the dickkopf family of Wnt signalling modulators because of its close association with aldosterone-producing cells in humans (11). Inactivation of Dkk3 in the Kcnk3 null background causes extension of the hyperaldosteronemic phenotype and increased expression of Cyp11b2 in the adrenal gland to the male sex, without affecting functional zonation. These data indicate that Dkk3 is a component of the genetic circuitry regulating expression of Cyp11b2 and suggest that it may be implicated in the pathogenesis of low-renin hyperaldosteronism in humans. One color -experiment with 2 strains of mice: C57BL/6 WT or Kcnk3 null (KO): male and female in basal conditions or following hormonal treatment (castration for males and testosterone injection for females), corresponding to 8 groups of animals. Total of 24 samples (n=3).

Project description:Primary aldosteronism (PA) is a common form of endocrine hypertension suspected in the presence of arterial hypertension (HT), hypokalemia and low plasma renin levels. While for a long time the genetic causes of PA have remained mysterious, recent findings have revealed an important role for an altered function of potassium channels in the pathogenesis of this disease. The basis for the unique sensitivity of adrenal zona glomerulosa (ZG) cells for plasma potassium concentration is a very high background potassium conductance, which is dependent on expression at high levels of two 2-pore domain (K2P) potassium channels, Task1 (KCNK3) and Task3 (KCNK9. Recent studies have shown that mice lacking Kcnk3 (Task1) or both Kcnk3 and Kcnk9 have PA. In Kcnk3 null mice, hyperaldosteronism is present in young animals of either sex, but is corrected in males after puberty. Strikingly, in these animals hyperaldosteronism associates with abnormal adrenal cortex functional zonation, since Cyp11b2, the rate-limiting enzyme for aldosterone production, is expressed in the inner region of the adrenal cortex and not in the glomerulosa. Additionally, this phenotype is under the control of sex hormones, as shown by the fact that castration of male Kcnk3 -/- animals prevents normal Cyp11b2 distribution, while testosterone injection in female Kcnk3 null mice restores expression of Cyp11b2 in ZG cells. We took advantage of the unique characteristics of the Kcnk3 null mouse model to search for genes that can modify their phenotype of PA and adrenocortical functional zonation. Using gene expression profiling in the adrenal glands of Kcnk3 null mice and exploiting the possibility of modulation of their phenotype by sexual hormones, we identified a cluster of genes closely associated with hyperaldosteronism in a sex- and hormone-dependent dynamic fashion. Among these genes, we focused our attention on Dkk3 (dickkopf3), encoding a peculiar member of the dickkopf family of Wnt signalling modulators because of its close association with aldosterone-producing cells in humans (11). Inactivation of Dkk3 in the Kcnk3 null background causes extension of the hyperaldosteronemic phenotype and increased expression of Cyp11b2 in the adrenal gland to the male sex, without affecting functional zonation. These data indicate that Dkk3 is a component of the genetic circuitry regulating expression of Cyp11b2 and suggest that it may be implicated in the pathogenesis of low-renin hyperaldosteronism in humans.

Project description:Primary aldosteronism (PA) is the most common endocrine hypertension comprising 10% of hypertensive patients. A recent series of transcriptome analyses using DNA microarray has shown that neumerous genes are differentially expressed between aldosterone-producing adenoma (APA) and its adjacent adrenal gland (AAG) tissue from the same patient. However, the molecular mechanism(s) of pathogenesis of APA has not yet been fully clarified. Although growing body of evidence has shown that epigenetic abnormalities including DNA methylation play a key role in tumorigenesis, there are few studies with regard to DNA methylation in APA. In the present study, to elucidate the pathogenic relationship between gene expression and DNA methylation in PA, we conducted an integrated analysis of transcriptome and methylome data for paired APA-AAG samples from the same patient. Adrenal specimens were obtained from 7 Japanese patients with APA, who underwent adrenalectomy at Tokyo Medical and Dental University. RNA and DNA samples were extracted from those 7 paired APA and AAG tissues. Gene expression and genome-wide DNA methylation profiles were obtained using SurePrint G3 Human GE 8x60K Microarray (Agilent) and Infinium HumanMethylation450 Beadchip (Illumina), respectively. Transcriptome anlaysis identified 244 significantly (2 fold<) upregulated genes in APA compared to AAG. The upregulated genes include the previously studied genes such as PCP4, ALDH1A2, and CYP11B2, and other genes that have not been previously studied, such as HOXA9, HOXA11, and HOXB9. Gene ontology (GO) analysis for these upregulated genes identified the calcium signaling pathway to be most significantly enriched with the upregulated genes (8 genes). Methylome analysis revealed that APA was globally hypomethylated compared to AAG regardless of gene feature groups, namely, TSS1500, TSS200, 5’UTR, 1stExon, gene body, and 3’UTR. GO analysis for the genes showing hypomethylation at TSS1500/TSS200 regions in APA identified the term “cytokine-cytokine receptor interaction” to be most significantly enriched with hypomethylated genes (37 genes). Integrated analysis of gene expression and genome-wide DNA methylation profiles identified 18 genes that are upregulated and whose TSS1500/TSS200 regions are hypomethylated in APA compared to AAG. These genes include CYP11B2 and MC2R (ACTH receptor). In conclusion, this is the first genome-wide study for PA that integrated transcriptome and methylome data. Global DNA hypomethylation in APA and concordant transcriptional up-regulation of some key genes, such as CYP11B2 and MC2R, may play crucial roles in the pathophysiological significance in PA. Adrenal specimens were obtained from 7 Japanese patients with APA, who underwent adrenalectomy at Tokyo Medical and Dental University. RNA and DNA samples were extracted from those 7 paired APA and AAG tissues. Gene expression and genome-wide DNA methylation profiles were obtained using SurePrint G3 Human GE 8x60K Microarray (Agilent) and Infinium HumanMethylation450 Beadchip (Illumina), respectively.

Project description:Primary aldosteronism (PA) is the most common endocrine hypertension comprising 10% of hypertensive patients. A recent series of transcriptome analyses using DNA microarray has shown that neumerous genes are differentially expressed between aldosterone-producing adenoma (APA) and its adjacent adrenal gland (AAG) tissue from the same patient. However, the molecular mechanism(s) of pathogenesis of APA has not yet been fully clarified. Although growing body of evidence has shown that epigenetic abnormalities including DNA methylation play a key role in tumorigenesis, there are few studies with regard to DNA methylation in APA. In the present study, to elucidate the pathogenic relationship between gene expression and DNA methylation in PA, we conducted an integrated analysis of transcriptome and methylome data for paired APA-AAG samples from the same patient. Adrenal specimens were obtained from 7 Japanese patients with APA, who underwent adrenalectomy at Tokyo Medical and Dental University. RNA and DNA samples were extracted from those 7 paired APA and AAG tissues. Gene expression and genome-wide DNA methylation profiles were obtained using SurePrint G3 Human GE 8x60K Microarray (Agilent) and Infinium HumanMethylation450 Beadchip (Illumina), respectively. Transcriptome anlaysis identified 244 significantly (2 fold<) upregulated genes in APA compared to AAG. The upregulated genes include the previously studied genes such as PCP4, ALDH1A2, and CYP11B2, and other genes that have not been previously studied, such as HOXA9, HOXA11, and HOXB9. Gene ontology (GO) analysis for these upregulated genes identified the calcium signaling pathway to be most significantly enriched with the upregulated genes (8 genes). Methylome analysis revealed that APA was globally hypomethylated compared to AAG regardless of gene feature groups, namely, TSS1500, TSS200, 5’UTR, 1stExon, gene body, and 3’UTR. GO analysis for the genes showing hypomethylation at TSS1500/TSS200 regions in APA identified the term “cytokine-cytokine receptor interaction” to be most significantly enriched with hypomethylated genes (37 genes). Integrated analysis of gene expression and genome-wide DNA methylation profiles identified 18 genes that are upregulated and whose TSS1500/TSS200 regions are hypomethylated in APA compared to AAG. These genes include CYP11B2 and MC2R (ACTH receptor). In conclusion, this is the first genome-wide study for PA that integrated transcriptome and methylome data. Global DNA hypomethylation in APA and concordant transcriptional up-regulation of some key genes, such as CYP11B2 and MC2R, may play crucial roles in the pathophysiological significance in PA.

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CLCN2 Chloride Channel Mutations in Familial Hyperaldosteronism Type II

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