Kinetics of Intermediate Release Enhances P450 11B2-Catalyzed Aldosterone Synthesis.

The mitochondrial enzyme cytochrome P450 11B2 (aldosterone synthase) catalyzes the 3 terminal transformations in the biosynthesis of aldosterone from 11-deoxycorticosterone (DOC): 11ß-hydroxylation to corticosterone, 18-hydroxylation, and 18-oxidation. Prior studies have shown that P450 11B2 produces more aldosterone from DOC than from the intermediate corticosterone and that the reaction sequence is processive, with intermediates remaining bound to the active site between oxygenation reactions. In contrast, P450 11B1 (11ß-hydroxylase), which catalyzes the terminal step in cortisol biosynthesis, shares a 93% amino acid sequence identity with P450 11B2, converts DOC to corticosterone, but cannot synthesize aldosterone from DOC. The biochemical and biophysical properties of P450 11B2, which enable its unique 18-oxygenation activity and processivity, yet are not also represented in P450 11B1, remain unknown. To understand the mechanism of aldosterone biosynthesis, we introduced point mutations at residue 320, which partially exchange the activities of P450 11B1 and P450 11B2 (V320A and A320V, respectively). We then investigated NADPH coupling efficiencies, binding kinetics and affinities, and product formation of purified P450 11B1 and P450 11B2, wild-type, and residue 320 mutations in phospholipid vesicles and nanodiscs. Coupling efficiencies for the 18-hydroxylase reaction with corticosterone as the substrate failed to correlate with aldosterone synthesis, ruling out uncoupling as a relevant mechanism. Conversely, corticosterone dissociation rates correlated inversely with aldosterone production. We conclude that intermediate dissociation kinetics, not coupling efficiency, enable P450 11B2 to synthesize aldosterone via a processive mechanism. Our kinetic data also suggest that the binding of DOC to P450 11B enzymes occurs in at least two distinct steps, favoring an induced-fit mechanism.

Zona Glomerulosa-Derived Klotho Modulates Aldosterone Synthase Expression in Young Female Mice.

Klotho plays a critical role in the regulation of ion and fluid homeostasis. A previous study reported that haplo-insufficiency of Klotho in mice results in increased aldosterone synthase (CYP11B2) expression, elevated plasma aldosterone, and high blood pressure. This phenotype was presumed to be the result of diminished Klotho expression in zona glomerulosa (zG) cells of the adrenal cortex; however, systemic effects on adrenal aldosterone production could not be ruled out. To examine whether Klotho expressed in the zG is indeed a critical regulator of aldosterone synthesis, we generated a tamoxifen-inducible, zG-specific mouse model of Klotho deficiency by crossing Klotho-flox mice with Cyp11b2-CreERT mice (zG-Kl-KO). Tamoxifen-treated Cyp11b2-CreERT animals (zG-Cre) served as controls. Rosa26-mTmG reporter mice were used for Cre-dependent lineage-marking. Two weeks after tamoxifen induction, the specificity of the zG-Cre line was verified using immunofluorescence analysis to show that GFP expression was restricted to the zG. RNA in situ hybridization revealed a 65% downregulation of Klotho messenger RNA expression in the zG of zG-Kl-KO female mice at age 12 weeks compared to control mice. Despite this significant decrease, zG-Kl-KO mice exhibited no difference in plasma aldosterone levels. However, adrenal CYP11B2 expression and the CYP11B2 promotor regulatory transcription factors, NGFIB and Nurr1, were enhanced. Together with in vitro experiments, these results suggest that zG-derived Klotho modulates Cyp11b2 but does not evoke a systemic phenotype in young adult mice on a normal diet. Further studies are required to investigate the role of adrenal Klotho on aldosterone synthesis in aged animals.

Chronic activation of adrenal Gq signaling induces Cyp11b2 expression in the zona fasciculata and hyperaldosteronism.

Hyperaldosteronism is often associated with inappropriate aldosterone production and aldosterone synthase (Cyp11b2) expression. Normally, Cyp11b2 expression is limited to the adrenal zona glomerulosa (ZG) and regulated by angiotensin II which signals through Gq protein-coupled receptors. As cells migrate inwards, they differentiate into 11ß-hydroxylase-expressing zona fasciculata (ZF) cells lacking Cyp11b2. The mechanism causing ZG-specific aldosterone biosynthesis is still unclear. We investigated the effect of chronic Gq signaling using transgenic mice with a clozapine N-oxide (CNO)-activated human M3 muscarinic receptor (DREADD) coupled to Gq (hM3Dq) that was expressed throughout the adrenal cortex. CNO raised circulating aldosterone in the presence of a high sodium diet with greater response seen in females compared to males. Immunohistochemistry and transcriptomics indicated disrupted zonal Cyp11b2 expression while Wnt signaling remained unchanged. Chronic Gq-DREADD signaling also induced an intra-adrenal RAAS in CNO-treated mice. Chronic Gq signaling disrupted adrenal cortex zonal aldosterone production associated with ZF expression of Cyp11b2.

Chimeric Genes Causing 11ß-Hydroxylase Deficiency: Implications in Clinical and Molecular Diagnosis.

Deficiency of 11ß-hydroxylase (11ß-OHD) is the second most common cause of congenital adrenal hyperplasia (CAH), accounting for 0.2-8% of all cases. The disease is transmitted as an autosomal recessive trait and the underlying genetic causes of 11ß-OHD are primarily small pathogenic variants affecting the CYP11B1 gene coding the 11ß-hydroxylase enzyme. However, special events complicate the molecular diagnosis of 11ß-OHD such as an unequal crossing over between the CYP11B2 (coding aldosterone synthase enzyme) and CYP11B1 genes. The resulting allele contains a hybrid gene, with a CYP11B2 5'-end and a CYP11B1 3'-end, where the CYP11B1 gene is under the control of the CYP11B2 promoter and thus not responding to the adrenocorticotropin (ACTH) but to angiotensin II and K+. This leads a reduction of cortisol production in 11ß-OHD. In particular, CYP11B2/CYP11B1 chimeric genes can be distinguished into two groups depending on the breakpoint site: chimeras with breakpoint after the exon 5 of CYP11B2 preserve the aldosterone synthase activity, the others with breakpoint before exon 5 lose this function. In the last case, a more severe phenotype is expected. The aim of this review was to explore the setting of CYP11B2/CYP11B1 chimeras in 11ß-OHD, performing a careful review of clinical literature cases.

No extra-adrenal aldosterone production in various human cell lines.

Extra-adrenal de novo aldosterone (Aldo) production has been described inconsistently. Systematic data based upon state-of-the-art technology including validated controls are sparse. We hypothesized that aldosterone synthase (CYP11B2) expression and de novo Aldo production are absent in nonadrenal human cell lines, either immortalized cell lines or commercially available primary cell lines, including peripheral blood mononuclear cells (PBMCs) of individuals without and with primary hyperaldosteronism (PA). CYP11B2-transfected COS-7 and endogenous CYP11B2 expressing adrenal H295R cells served as positive controls. Various well-characterized, purchased, immortalized (BeWo, HEK293, HTR-8/SVneo, JEG-3) and primary (HAEC, HLEC, HRGEC, HRMC, HUAEC, HUVEC, PBMC) cell lines as well as self-isolated PBMCs from PA patients (n = 5) were incubated with the steroid hormone substrates progesterone, deoxycorticosterone, corticosterone or 18-OH-corticosterone with and without Ang II for 24 h to assess CYP11B2 enzymatic activity. CYP11B2 expression was analyzed by real-time PCR and liquid chromatography-mass spectrometry was used to quantify Aldo production. Pronounced CYP11B2 mRNA expression and Aldo production were observed in both positive controls, which followed an incremental time course. Neither substrates alone nor coincubation with Ang II significantly stimulated CYP11B2 expression or Aldo production in various immortalized and primary cell lines and PBMCs of PA patients. These results strongly support the absence of relevant de novo extra-adrenal Aldo production in nonadrenal cells, including blood mononuclear cells, irrespective of the absence or presence of autonomous adrenal Aldo production.

Neonatal salt wasting syndrome: Aldosterone synthase deficiency caused by a new splicing variant in CYP11B2.

Aldosterone synthase deficiency (ASD) is a rare autosomal recessive disorder involving isolated aldosterone deficiency without any compromise of other adrenal hormones. This condition manifests mainly in the neonatal period and in infants as a salt wasting syndrome with vomiting and failure to thrive. Due to its potentially life-threatening effects, ASD requires a careful and early diagnosis based on appropriate hormonal investigations in order to initiate adequate management: rehydration as well as salt and fludrocortisone supplementation. Genetic analysis of the CYP11B2 gene will confirm ASD in most cases. We report the case of a newborn with a typical clinical presentation associated with some uncommon phenotypic features (hyperhidrosis, liver injury). Furthermore, our patient carries a new CYP11B2 splicing variant to be added to the approximately 60 pathogenic or likely pathogenic variants already reported.

Aldosterone and aldosterone synthase inhibitors in cardiorenal disease.

Modulation of the renin-angiotensin-aldosterone system is a foundation of therapy for cardiovascular and kidney diseases. Excess aldosterone plays an important role in cardiovascular disease, contributing to inflammation, fibrosis, and dysfunction in the heart, kidneys, and vasculature through both genomic and mineralocorticoid receptor (MR)-mediated as well as nongenomic mechanisms. MR antagonists have been a key therapy for attenuating the pathologic effects of aldosterone but are associated with some side effects and may not always adequately attenuate the nongenomic effects of aldosterone. Aldosterone is primarily synthesized by the CYP11B2 aldosterone synthase enzyme, which is very similar in structure to other enzymes involved in steroid biosynthesis including CYP11B1, a key enzyme involved in glucocorticoid production. Lack of specificity for CYP11B2, off-target effects on the hypothalamic-pituitary-adrenal axis, and counterproductive increased levels of bioactive steroid intermediates such as 11-deoxycorticosterone have posed challenges in the development of early aldosterone synthase inhibitors such as osilodrostat. In early-phase clinical trials, newer aldosterone synthase inhibitors demonstrated promise in lowering blood pressure in patients with treatment-resistant and uncontrolled hypertension. It is therefore plausible that these agents offer protection in other disease states including heart failure or chronic kidney disease. Further clinical evaluation will be needed to clarify the role of aldosterone synthase inhibitors, a promising class of agents that represent a potentially major therapeutic advance.

Case Report: A combination of chimeric CYP11B2/CYP11B1 and a novel p.Val68Gly CYP11B1 variant causing 11ß-Hydroxylase deficiency in a Chinese patient.

Introduction: 11ß-Hydroxylase deficiency (11ß-OHD, OMIM#202010) is the second most common form of congenital adrenal hyperplasia (CAH) caused by pathogenic variants in the CYP11B1 gene. Both single nucleotide variations (SNV)/small insertion and deletion and genomic rearrangements of CYP11B1 are important causes of 11ß-OHD. Among these variant types, pathogenic CYP11B2/CYP11B1 chimeras only contribute to a minority of cases. Heterozygote cases (chimera combined with SNV) are very rare, and genetic analysis of these cases can be challenging. Case presentation: We presented a suspected 11ß-OHD female patient with incomplete virilization, adrenal hyperplasia, and hypokalemia hypertension. Whole exome sequencing (WES) revealed that the patient carried both a chimeric CYP11B2/CYP11B1 and a novel missense variant, NM_000497.4: c.203T>G, p.Val68Gly (chr8:143961027) in CYP11B1, which were confirmed by CNVplex and Sanger sequencing, respectively. The patient's manifestations and genetic findings confirmed the diagnosis of 11ß-OHD, and oral dexamethasone was administered as a subsequent treatment. Conclusion: This report showed a rare CYP11B2/CYP11B1 chimera combined with a novel missense variant in a 11ß-OHD female patient. The result expands variant spectrum of CYP11B1 and suggests that both chimera and CYP11B1 variant screening should be performed simultaneously in suspected cases of 11ß-OHD. To our knowledge, this is the first report about CYP11B2/CYP11B1 chimera detected by WES analysis. WES combined with CNV analysis is an efficient method in the genetic diagnosis of this rare and complex disorder.

Pathology and gene mutations of aldosterone-producing lesions.

The human adrenal cortex secretes aldosterone and cortisol as major corticosteroids. For their production, CYP11B2 and CYP11B1 catalyze the last steps in the syntheses of aldosterone and cortisol, respectively. In our previous study, CYP11B2 was the first successfully purified from rat adrenals and human clinical samples and then was proved to be aldosterone synthase. We demonstrated the immunohistochemistry for CYP11B2 of both rats and humans and applied it clinically to visualize the functional histology of aldosterone-producing adenoma (APA) causing primary aldosteronism (PA). We discovered aldosterone-producing cell clusters (APCCs) and possible APCC-to-APA transitional lesions (pAATLs) and further visualized aldosterone-producing lesions for rare forms of PA including familial hyperaldosteronism type 3 and novel non-familial juvenile PA. Here we review the history of our research on aldosterone-producing lesions.

Unequal crossing over between CYP11B2 and CYP11B1 causes 11 ß -hydroxylase deficiency in a consanguineous family.

Cytochrome P450 (CYP) family CYP11B2/CYP11B1 chimeric genes have been shown to arise from unequal crossing over of the genes encoding aldosterone synthase (CYP11B2) and 11ß-hydroxylase (CYP11B1) during meiosis. The activity deficiency or impaired activity of aldosterone synthase and 11ß-hydroxylase resulting from these chimeric genes are important reasons for 11ß-hydroxylase deficiency (11ß-OHD). Here，two patients with pseudoprecocious puberty and hypokalemia hypertension and three carriers in a consanguineous marriage family were studied. A single CYP11B2/CYP11B1 chimera consisting of the promoter and exons 1 through 5 of CYP11B2, exons 8 and 9 of CYP11B1, and a breakpoint consisting of part of exon 6 of CYP11B2 and part of exon 6, intron 6, and exon 7 of CYP11B1 were detected in the patients and carriers. At the breakpoint of the chimera, a c 0.1086 G > C ( p.Leu.362 =) synonymous mutation in exon 6 of CYP11B2, a c 0.1157 C＞G(p. A386V) missense mutation in exon 7 of CYP11B1, and an intronic mutation in intron 6 were detected. The allele model of the CYP11B2/CYP11B1 chimera demonstrated homozygosity and heterozygosity in the patients and the carriers, respectively. Molecular docking and enzymatic activity analyses indicated that the CYP11B2/CYP11B1 chimeric protein interacted with the catalytic substrate of aldosterone synthase and had similar enzymatic activity to aldosterone synthase. Our study indicated that deletion of CYP11B1 and CYP11B2 abolished the enzymatic activity of 11 ß-hydroxylase and aldosterone synthase; however, the compensation of the enzymatic activity of aldosterone synthase by the CYP11B2/CYP11B1 chimeric protein maintained normal aldosterone levels in vitro. All of the above findings explained the 11ß-OHD phenotypes of the proband and patients in the family.

Aldosterone Biosynthesis Is Potently Stimulated by Perfluoroalkyl Acids: A Link between Common Environmental Pollutants and Arterial Hypertension.

The large environmental contamination of drinking water by perfluoroalkyl substances (PFAS) markedly increased the plasma levels of pentadecafluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) in a Northern Italy population with a high prevalence of arterial hypertension and cardiovascular disease. As the link between PFAS and arterial hypertension is unknown, we investigated if they enhance the biosynthesis of the well-known pressor hormone aldosterone. We found that PFAS increased aldosterone synthase (CYP11B2) gene expression by three-fold and doubled aldosterone secretion and cell and mitochondria reactive oxygen species (ROS) production over controls (p < 0.01 for all) in human adrenocortical carcinoma cells HAC15. They also enhanced the effects of Ang II on CYP11B2 mRNA and aldosterone secretion (p < 0.01 for all). Moreover, when added 1 h before, the ROS scavenger tempol abolished the effect of PFAS on CYP11B2 gene expression. These results indicate that at concentrations mimicking those found in human plasma of exposed individuals, PFAS are potent disruptors of human adrenocortical cell function, and might act as causative factors of human arterial hypertension via increased aldosterone production.

Calcineurin regulates aldosterone production via dephosphorylation of NFATC4.

The mineralocorticoid aldosterone, secreted by the adrenal zona glomerulosa (ZG), is critical for life, maintaining ion homeostasis and blood pressure. Therapeutic inhibition of protein phosphatase 3 (calcineurin, Cn) results in inappropriately low plasma aldosterone levels despite concomitant hyperkalemia and hyperreninemia. We tested the hypothesis that Cn participates in the signal transduction pathway regulating aldosterone synthesis. Inhibition of Cn with tacrolimus abolished the potassium-stimulated (K+-stimulated) expression of aldosterone synthase, encoded by CYP11B2, in the NCI-H295R human adrenocortical cell line as well as ex vivo in mouse and human adrenal tissue. ZG-specific deletion of the regulatory Cn subunit CnB1 diminished Cyp11b2 expression in vivo and disrupted K+-mediated aldosterone synthesis. Phosphoproteomics analysis identified nuclear factor of activated T cells, cytoplasmic 4 (NFATC4), as a target for Cn-mediated dephosphorylation. Deletion of NFATC4 impaired K+-dependent stimulation of CYP11B2 expression and aldosterone production while expression of a constitutively active form of NFATC4 increased expression of CYP11B2 in NCI-H295R cells. Chromatin immunoprecipitation revealed NFATC4 directly regulated CYP11B2 expression. Thus, Cn controls aldosterone production via the Cn/NFATC4 pathway. Inhibition of Cn/NFATC4 signaling may explain low plasma aldosterone levels and hyperkalemia in patients treated with tacrolimus, and the Cn/NFATC4 pathway may provide novel molecular targets to treat primary aldosteronism.

Association between Aldosterone Synthase (CYP11B2) Gene Polymorphism and Hypertension in Pashtun Ethnic Population of Khyber Pakhtunkwha, Pakistan.

Genome-wide association studies significantly increased the number of hypertension risk variants; however, most of them focused on European societies. There is lack of such studies in developing countries, including Pakistan. The lack of research studies and the high prevalence of hypertension in the Pakistani community prompted us to design this study. Aldosterone synthase (CYP11B2) was thoroughly studied in different ethnic groups; however, no such study has been conducted in the Pashtun population of Khyber Pakhtunkhwa, Pakistan. In essential hypertension, the aldosterone synthase gene (CYP11B2) plays a significant role. Aldosterone synthesis is affected by both hereditary and environmental factors. Aldosterone synthase (encoded by the CYP11B2 gene) controls the conversion of deoxycorticosterone to aldosterone and, thus, has genetic influences. Polymorphisms in the CYP11B2 gene are linked to an increased risk of hypertension. Previous research on the polymorphism of the aldosterone synthase (CYP11B2) gene and its relationship to hypertension produced inconclusive results. The present study investigates the relationship between CYP11B2 gene polymorphism and hypertension in Pakistan's Pashtun population. We used the nascent exome sequencing method to identify variants associated with hypertension. The research was divided into two phases. In phase one, DNA samples from 200 adult hypertension patients (of age ≥ 30 years) and 200 controls were pooled (n = 200/pool) and subjected to Exome Sequencing. In the second phase, the WES reported SNPs were genotyped using the Mass ARRAY technique to verify and confirm the association between WES-identified SNPs and hypertension. WES identified a total of eight genetic variants in the CYP11B2 gene. The chi-square test and logistic regression analysis were used to estimate the minor allele frequencies (MAFs) and chosen SNPs relationships with hypertension. The frequency of minor allele T was found to be higher in cases compared to the control (42% vs. 30%: p = 0.001) for rs1799998 of CYP11B2 gene, while no significant results (p > 0.05) were observed for the remaining SNPs; rs4536, rs4537, rs4545, rs4543, rs4539, rs4546 and rs6418 showed no positive association with HTN in the studied population (all p > 0.05). Our study findings suggest that rs1799998 increases susceptibly to HTN in the Pashtun population of KP, Pakistan.

Primary Aldosteronism: Spatial Multiomics Mapping of Genotype-Dependent Heterogeneity and Tumor Expansion of Aldosterone-Producing Adenomas.

BACKGROUND: Primary aldosteronism is frequently caused by an adrenocortical aldosterone-producing adenoma (APA) carrying a somatic mutation that drives aldosterone overproduction. APAs with a mutation in KCNJ5 (APA-KCNJ5MUT) are characterized by heterogeneous CYP11B2 (aldosterone synthase) expression, a particular cellular composition and larger tumor diameter than those with wild-type KCNJ5 (APA-KCNJ5WT). We exploited these differences to decipher the roles of transcriptome and metabolome reprogramming in tumor pathogenesis. METHODS: Consecutive adrenal cryosections (7 APAs and 7 paired adjacent adrenal cortex) were analyzed by spatial transcriptomics (10x Genomics platform) and metabolomics (in situ matrix-assisted laser desorption/ionization mass spectrometry imaging) co-integrated with CYP11B2 immunohistochemistry. RESULTS: We identified intratumoral transcriptional heterogeneity that delineated functionally distinct biological pathways. Common transcriptomic signatures were established across all APA specimens which encompassed 2 distinct transcriptional profiles in CYP11B2-immunopositive regions (CYP11B2-type 1 or 2). The CYP11B2-type 1 signature was characterized by zona glomerulosa gene markers and was detected in both APA-KCNJ5MUT and APA-KCNJ5WT. The CYP11B2-type 2 signature displayed markers of the zona fasciculata or reticularis and predominated in APA-KCNJ5MUT. Metabolites that promote oxidative stress and cell death accumulated in APA-KCNJ5WT. In contrast, antioxidant metabolites were abundant in APA-KCNJ5MUT. Finally, APA-like cell subpopulations-negative for CYP11B2 gene expression-were identified in adrenocortical tissue adjacent to APAs suggesting the existence of tumor precursor states. CONCLUSIONS: Our findings provide insight into intra- and intertumoral transcriptional heterogeneity and support a role for prooxidant versus antioxidant systems in APA pathogenesis highlighting genotype-dependent capacities for tumor expansion.

Unexpectedly high mutation rate of cyp11b1 compared to cyp21a2 in randomly-selected turkish women: a large screening study.

PURPOSE: Congenital adrenal hyperplasia (CAH) is a group of autosomal recessive disorders resulting from enzyme deficiencies associated with steroidogenesis. The clinical presentation of non-classic CAH (NCAH) in females is often indistinguishable from other hyperandrogenic disorders like polycystic ovary syndrome (PCOS). The data on the prevalence of NCAH in unselected women in the literature is scanty. The research aimed to evaluate the prevalence of NCAH, carrier frequencies, and the correlation between clinical symptoms and genotype in Turkish women. METHODS: The study group comprised two hundred and seventy randomly-selected unrelated asymptomatic women of reproductive age (18-45). Subjects were recruited from female blood donors. All volunteers underwent clinical examination and hormone measurements. The protein-encoding exons and exon-intron boundaries of the CYP21A2, CYP11B1, HSD3ß2 and CYP21A2 promoter were sequenced by direct DNA sequencing. RESULTS: After genotyping, seven (2.2%) individuals were diagnosed with NCAH. The heterozygous carrier frequencies of CYP21A2, CYP21A2 promoter, CYP11B1, and HSD3ß2 genes with 34, 34, 41, and 1 pathologic mutation were determined at 12.6%, 12.6%, 15.2%, and 0.37% of volunteers, respectively. Gene-conversion (GC) frequencies between CYP21A2/CYP21A1P and CYP11B1/CYP11B2 were determined as 10.4% and 14.8%, respectively. CONCLUSION: Despite GC-derived higher mutation frequency determined in the CYP11B1 gene, the reason for the low frequency of NCAH due to 11OHD compared to 21OHD might be that gene-conversion arises with active CYP11B2 rather than an inactive pseudogene. HSD3ß1 exhibits high homology with HSD3ß2 located on the same chromosome; remarkably, it demonstrates low heterozygosity and no GC, most probably the outcome of a tissue-specific expression pattern.

Different cell compositions and a novel somatic KCNJ5 variant found in a patient with bilateral adrenocortical adenomas secreting aldosterone and cortisol.

Introduction: This study aimed to explore the possible pathogenesis of a rare case of co-existing Cushing's syndrome (CS) and primary aldosteronism (PA) caused by bilateral adrenocortical adenomas secreting aldosterone and cortisol, respectively. Methods: A 41-year-old Chinese woman with severe hypertension and hypokalemia for 5 and 2 years, respectively, was referred to our hospital. She had a Cushingoid appearance. Preoperative endocrinological examinations revealed autonomous cortisol and aldosterone secretion. Computed tomography revealed bilateral adrenal adenomas. Subsequently, adrenal vein sampling and sequential left and right partial adrenalectomy indicated the presence of a left aldosterone-producing tumor and a right cortisol-producing tumor. Pathological examination included immunohistochemical analysis of the resected specimens. Secretions of aldosterone and cortisol were observed both in vivo and in vitro. Further, whole-exome sequencing was performed for DNA that was extracted from peripheral blood leukocytes and bilateral adrenal adenomas in order to determine whether the patient had relevant variants associated with PA and CS. Results: Immunohistochemical staining revealed that the left adenoma primarily comprised clear cells expressing CYP11B2, whereas the right adenoma comprised both eosinophilic compact and clear cells expressing CYP11B1. The mRNA levels of steroidogenic enzymes (including CYP11B1 and CYP17A1) were high in the right adenoma, whereas CYP11B2 was highly expressed in the left adenoma. A novel somatic heterozygous missense variant-KCNJ5 c.503T > G (p.L168R)-was detected in the left adrenal adenoma, but no other causative variants associated with PA and CS were detected in the peripheral blood or right adrenocortical adenoma. In the primary cell culture of the resected hyperplastic adrenal adenomas, verapamil and nifedipine, which are two calcium channel blockers, markedly inhibited the secretion of both aldosterone and cortisol. Conclusion: We present an extremely rare case of bilateral adrenocortical adenomas with distinct secretion of aldosterone and cortisol. The heterogeneity of the tumor cell compositions of aldosterone- and cortisol-producing adenoma (A/CPA) and somatic mutation of KCNJ5 may have led to different hormone secretions in the bilateral adrenal adenomas.

Molecular and Epigenetic Control of Aldosterone Synthase, CYP11B2 and 11-Hydroxylase, CYP11B1.

Aldosterone and cortisol serve important roles in the pathogenesis of cardiovascular diseases and metabolic disorders. Epigenetics is a mechanism to control enzyme expression by genes without changing the gene sequence. Steroid hormone synthase gene expression is regulated by transcription factors specific to each gene, and methylation has been reported to be involved in steroid hormone production and disease. Angiotensin II or potassium regulates the aldosterone synthase gene, CYP11B2. The adrenocorticotropic hormone controls the 11b-hydroxylase, CYP11B1. DNA methylation negatively controls the CYP11B2 and CYP11B1 expression and dynamically changes the expression responsive to continuous stimulation of the promoter gene. Hypomethylation status of the CYP11B2 promoter region is seen in aldosterone-producing adenomas. Methylation of recognition sites of transcription factors, including cyclic AMP responsive element binding protein 1 or nerve growth factor-induced clone B, diminish their DNA-binding activity. A methyl-CpG-binding protein 2 cooperates directly with the methylated CpG dinucleotides of CYP11B2. A low-salt diet, treatment with angiotensin II, and potassium increase the CYP11B2 mRNA levels and induce DNA hypomethylation in the adrenal gland. A close association between a low DNA methylation ratio and an increased CYP11B1 expression is seen in Cushing's adenoma and aldosterone-producing adenoma with autonomous cortisol secretion. Epigenetic control of CYP11B2 or CYP11B1 plays an important role in autonomic aldosterone or cortisol synthesis.

[Genetic analysis of a case with 11ß hydroxylase deficiency caused by CYP11B2/CYP11B1 chimeric gene].

OBJECTIVE: To analyze a child with 11ß hydroxylase deficiency (11ß-OHD) due to CYP11B2/CYP11B1 chimeric gene. METHODS: Clinical data of the child who was admitted to Henan Children's Hospital on August 24, 2020 were retrospectively analyzed. Peripheral blood samples of the child and his parents were collected and subjected to whole exome sequencing (WES). Candidate variant was verified by Sanger sequencing. RT-PCR and Long-PCR were carried out to verify the presence of chimeric gene. RESULTS: The patient, a 5-year-old male, had featured premature development of secondary sex characteristics and accelerated growth, and was diagnosed with 21 hydroxylase deficiency (21-OHD). WES revealed that he has harbored a heterozygous c.1385T>C (p.L462P) variant of the CYP11B1 gene, in addition to a 37.02 kb deletion on 8q24.3. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the c.1385T>C (p.L462P) was rated as a likely pathogenic variant (PM2_Supporting+PP3_Moderate+PM3+PP4). The results of RT-PCR and Long-PCR suggested that CYP11B1 and CYP11B2 genes have recombined to form a CYP11B2 exon 1~7/CYP11B1 exon 7~9 chimeric gene. The patient was diagnosed as 11ß-OHD and effectively treated with hydrocortisone and triptorelin. A healthy fetus was delivered following genetic counseling and prenatal diagnosis. CONCLUSION: 11ß-OHD may be misdiagnosed as 21-OHD due to the potential CYP11B2/CYP11B1 chimeric gene, which will require multiple methods for the detection.

18-Oxocortisol: A journey.

The search for mineralocorticoids to explain some cases of low renin hypertension with suppressed aldosterone levels led to the isolation of the abundant steroid 18-hydroxycortisol in human urine. 18-Hydroxycortisol proved to be inactive, but because of its similarity to precursors for the synthesis of aldosterone, bullfrog adrenals were incubated with cortisol, resulting in the discovery of 18-oxocortisol which is structurally similar to aldosterone, but with a 17α-hydroxy group like cortisol. 18-Oxocortisol is a weak mineralocorticoid. Its synthesis occurs primarily in the zona glomerulosa where co-expression of the CYP11B2 (aldosterone synthase) and the CYP17A1 (17α-hydroxylase) occurs in a variable number of cells. The clinical value of the measurement of 18-oxocortisol is that it serves to distinguish subtypes of primary aldosteronism. It is significantly elevated in patients with aldosterone-producing adenomas in comparison to those with idiopathic bilateral hyperaldosteronism and helps predict the type of somatic mutation in the aldosterone-producing adenomas, as it is higher in those with KCNJ5 mutations compared to other gene mutations.

Phospholipase D mediates very low-density lipoprotein-induced aldosterone production, in part, via lipin-1.

Aldosterone is considered to be a link between hypertension and obesity; obese individuals have high serum levels of very low-density lipoprotein (VLDL). VLDL has been shown to induce aldosterone production in multiple adrenal zona glomerulosa models, mediated in part by phospholipase D (PLD). PLD is an enzyme that hydrolyzes phosphatidylcholine to produce phosphatidic acid (PA), a lipid second messenger that can also be dephosphorylated by lipin to yield diacylglycerol (DAG), yet another lipid signal. However, it is unclear which of the two lipid second messengers, PA or DAG, underlies PLD's mediation of aldosterone production. We hypothesized that the key signal produced by PLD (indirectly) is DAG such that PLD mediates VLDL-induced aldosterone production via lipin-mediated metabolism of PA to DAG. To assess the role of lipin in VLDL-induced aldosterone production, lipin-1 was overexpressed (using an adenovirus) or inhibited (using propranolol) in HAC15 cells followed by treatment with or without VLDL. Lipin-1 overexpression enhanced the VLDL-stimulated increase in CYP11B2 expression (by 75%), and lipin-1 inhibition decreased the VLDL-stimulated increase in CYP11B2 expression (by 66%). Similarly, the VLDL-stimulated increase in aldosterone production was enhanced by lipin-1 overexpression (182%) and was decreased by lipin inhibition (80%). Our results are suggestive of DAG being the key lipid signal since manipulating lipin-1 levels/activity affects VLDL-stimulated steroidogenic gene expression and ultimately, aldosterone production. Our study warrants further investigation into VLDL-stimulated steroidogenic signaling pathways which may lead to the identification of novel therapeutic targets, such as lipin-1 and its downstream pathways, to potentially treat obesity-associated hypertension.