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Shalomov B, Handklo-Jamal R, Reddy HP, Theodor N, Bera AK, Dascal N. A revised mechanism of action of hyperaldosteronism-linked mutations in cytosolic domains of GIRK4 (KCNJ5). J Physiol 2021; 600:1419-1437. [PMID: 34957562 DOI: 10.1113/jp282690] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Accepted: 12/21/2021] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Mutations in GIRK4 (KCNJ5) G-protein gated channels cause primary aldosteronism, a major cause of secondary hypertension. The primary mechanism is believed to be loss of K+ selectivity. R52H and E246K, aldosteronism-causing mutations in cytosolic N- and C- termini of GIRK4, were reported to cause loss of K+ selectivity. We show that R52H, E246K and G247R mutations render homotetrameric GIRK channels non-functional. In heterotetrameric context with GIRK1, these mutations impair membrane expression, interaction with Gβγ and open probability, but do not alter K+ selectivity or inward rectification. In human aldosterone-secreting cell line, a GIRK4 opener and overexpression of heterotetrameric GIRK1/4WT , but not over-expression of GIRK1/4 mutants, reduced aldosterone secretion. Aldosteronism-causing mutations in cytosolic domain of GIRK4 are loss-of-function mutations rather than gain-of-function, selectivity-loss mutations. Deciphering of exact biophysical mechanism that impairs the channel is crucial for setting the course of treatment. ABSTRACT G-protein gated, inwardly rectifying potassium channels (GIRK) mediate inhibitory transmission in brain and heart, and are present in adrenal cortex. GIRK4 (KCNJ5) subunits are abundant in the heart and adrenal cortex. Multiple mutations of KCNJ5 cause primary aldosteronism (PA). Mutations in the pore region of GIRK4 cause loss of K+ selectivity, Na+ influx, and depolarization of zona glomerulosa cells followed by hypersecretion of aldosterone. The concept of selectivity loss has been extended to mutations in cytosolic domains of GIRK4 channels, remote from the pore. We expressed aldosteronism-linked GIRK4R52H , GIRK4E246K , and GIRK4G247R mutants in Xenopus oocytes. Whole-cell currents of heterotetrameric GIRK1/4R52H and GIRK1/4E246K channels were greatly reduced compared to GIRK1/4WT . Nevertheless, all heterotetrameric mutants retained full K+ selectivity and inward rectification. When expressed as homotetramers, only GIRK4WT , but none of the mutants, produced whole-cell currents. Confocal imaging, single channel and Förster Resonance Energy Transfer (FRET) analyses showed: 1) reduction of membrane abundance of all mutated channels, especially as homotetramers, 2) impaired interaction with Gβγ subunits, and 3) reduced open probability of GIRK1/4R52H . VU0529331, a GIRK4 opener, activated homotetrameric GIRK4G247R channels, but not GIRK4R52H and GIRK4E246K . In human adrenocortical carcinoma cell line (HAC15), VU0529331 and over-expression of heterotetrameric GIRK1/4WT , but not over-expression of GIRK1/4 mutants, reduced aldosterone secretion. Our results suggest that, contrary to pore mutants of GIRK4, non-pore mutants R52H and E246K mutants are loss-of-function rather than gain-of-function/selectivity-loss mutants. Hence, GIRK4 openers may be a potential course of treatment for patients with cytosolic N- and C-terminal mutations. Abstract Figure: There are two mutations types in KCNJ5 (GIRK4) that can cause excessive secretion of aldosterone, leading to primary aldosteronism. Mutations of the first type render the channel non-selective to monovalent cations and often constitutively active, thus depolarizing the zona granulosa cells. This previously described mechanism underlies the disease-causing effects of mutations of amino acid residues located in the pore region (red color). Blockers of the channel may be useful as potential treatment to reduce aldosterone secretion. Here we show that mutations of the second type, located in the cytosolic domain remote from the pore, act by a different mechanism. They do not alter channel's ion selectivity or rectification but cause poor expression or poor activation by Gβγ, resulting in a reduction in cell's K+ conductance and depolarization. In this case, GIRK4 openers can potentially be useful to prevent the excessive aldosterone secretion. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Boris Shalomov
- Department of Physiology and Pharmacology, School of Medicine, and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Reem Handklo-Jamal
- Department of Physiology and Pharmacology, School of Medicine, and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Haritha P Reddy
- Department of Physiology and Pharmacology, School of Medicine, and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 69978, Israel.,Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, 600036, India
| | - Neta Theodor
- Department of Physiology and Pharmacology, School of Medicine, and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Amal K Bera
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, 600036, India
| | - Nathan Dascal
- Department of Physiology and Pharmacology, School of Medicine, and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 69978, Israel
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Chen IS, Eldstrom J, Fedida D, Kubo Y. A novel ion conducting route besides the central pore in an inherited mutant of G-protein-gated inwardly rectifying K + channel. J Physiol 2021; 600:603-622. [PMID: 34881429 DOI: 10.1113/jp282430] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 11/25/2021] [Indexed: 01/21/2023] Open
Abstract
G-protein-gated inwardly rectifying K+ (GIRK; Kir3.x) channels play important physiological roles in various organs. Some of the disease-associated mutations of GIRK channels are known to induce loss of K+ selectivity but their structural changes remain unclear. In this study, we investigated the mechanisms underlying the abnormal ion selectivity of inherited GIRK mutants. By the two-electrode voltage-clamp analysis of GIRK mutants heterologously expressed in Xenopus oocytes, we observed that Kir3.2 G156S permeates Li+ better than Rb+ , while T154del or L173R of Kir3.2 and T158A of Kir3.4 permeate Rb+ better than Li+ , suggesting a unique conformational change in the G156S mutant. Applications of blockers of the selectivity filter (SF) pathway, Ba2+ or Tertiapin-Q (TPN-Q), remarkably increased the Li+ -selectivity of Kir3.2 G156S but did not alter those of the other mutants. In single-channel recordings of Kir3.2 G156S expressed in mouse fibroblasts, two types of events were observed, one attributable to a TPN-Q-sensitive K+ current and the second a TPN-Q-resistant Li+ current. The results show that a novel Li+ -permeable and blocker-resistant pathway exists in G156S in addition to the SF pathway. Mutations in the pore helix, S148F and T151A also induced high Li+ permeation. Our results demonstrate that the mechanism underlying the loss of K+ selectivity of Kir3.2 G156S involves formation of a novel ion permeation pathway besides the SF pathway, which allows permeation of various species of cations. KEY POINTS: G-protein-gated inwardly rectifying K+ (GIRK; Kir3.x) channels play important roles in controlling excitation of cells in various organs, such as the brain and the heart. Some of the disease-associated mutations of GIRK channels are known to induce loss of K+ selectivity but their structural changes remain unclear. In this study, we investigated the mechanisms underlying the abnormal ion selectivity of inherited mutants of Kir3.2 and Kir3.4. Here we show that a novel Na+ , Li+ -permeable and blocker-resistant pathway exists in an inherited mutant, Kir3.2 G156S, in addition to the conventional ion conducting pathway formed by the selectivity filter (SF). Our results demonstrate that the mechanism underlying the loss of K+ selectivity of Kir3.2 G156S involves formation of a novel ion permeation pathway besides the SF pathway, which allows permeation of various species of cations.
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Affiliation(s)
- I-Shan Chen
- Division of Biophysics and Neurobiology, Department of Molecular and Cellular Physiology, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Japan.,Department of Physiological Sciences, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Hayama, Japan.,Department of Pharmacology, School of Medicine, Wakayama Medical University, Wakayama, Japan
| | - Jodene Eldstrom
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, British Columbia, Canada
| | - David Fedida
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Yoshihiro Kubo
- Division of Biophysics and Neurobiology, Department of Molecular and Cellular Physiology, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Japan.,Department of Physiological Sciences, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Hayama, Japan
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Mashmoushi A, Choudhary A, Thomas CP, Wolf MT. A rare case of hyporeninemic hypertension: Answers. Pediatr Nephrol 2021; 36:569-573. [PMID: 32607771 PMCID: PMC7772256 DOI: 10.1007/s00467-020-04667-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 06/09/2020] [Indexed: 11/29/2022]
Affiliation(s)
- Ahmad Mashmoushi
- Pediatric Nephrology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Abha Choudhary
- Pediatric Endocrinology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Christie P. Thomas
- Division of Nephrology, Department of Internal Medicine, University of Iowa Health Care, Iowa City, IA, USA
| | - Matthias T.F. Wolf
- Pediatric Nephrology, University of Texas Southwestern Medical Center, Dallas, TX, USA
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4
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Tevosian SG, Fox SC, Ghayee HK. Molecular Mechanisms of Primary Aldosteronism. Endocrinol Metab (Seoul) 2019; 34:355-366. [PMID: 31884735 PMCID: PMC6935778 DOI: 10.3803/enm.2019.34.4.355] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 12/02/2019] [Accepted: 12/09/2019] [Indexed: 01/11/2023] Open
Abstract
Primary aldosteronism (PA) results from excess production of mineralocorticoid hormone aldosterone by the adrenal cortex. It is normally caused either by unilateral aldosterone-producing adenoma (APA) or by bilateral aldosterone excess as a result of bilateral adrenal hyperplasia. PA is the most common cause of secondary hypertension and associated morbidity and mortality. While most cases of PA are sporadic, an important insight into this debilitating disease has been derived through investigating the familial forms of the disease that affect only a minor fraction of PA patients. The advent of gene expression profiling has shed light on the genes and intracellular signaling pathways that may play a role in the pathogenesis of these tumors. The genetic basis for several forms of familial PA has been uncovered in recent years although the list is likely to expand. Recently, the work from several laboratories provided evidence for the involvement of mammalian target of rapamycin pathway and inflammatory cytokines in APAs; however, their mechanism of action in tumor development and pathophysiology remains to be understood.
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Affiliation(s)
- Sergei G Tevosian
- Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA
| | - Shawna C Fox
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Gainesville, FL, USA
| | - Hans K Ghayee
- Division of Endocrinology, Department of Medicine, Malcom Randall VA Medical Center, University of Florida, Gainesville, FL, USA.
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Chang CH, Hu YH, Tsai YC, Wu CH, Wang SM, Lin LY, Lin YH, Satoh F, Wu KD, Wu VC. Arterial stiffness and blood pressure improvement in aldosterone-producing adenoma harboring KCNJ5 mutations after adrenalectomy. Oncotarget 2018; 8:29984-29995. [PMID: 28415786 PMCID: PMC5444719 DOI: 10.18632/oncotarget.16269] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 03/09/2017] [Indexed: 12/18/2022] Open
Abstract
The aim of this study was to show the effect of KCNJ5 mutational status on arterial stiffness in aldosterone-producing adenomas after adrenalectomy. Between February 2008 and January 2010, we prospectively enrolled 108 aldosterone-producing adenoma patients undergoing adrenalectomy. We conducted repeated measurements of pulse wave velocity at baseline, 6 months, and 12 months after adrenalectomy, grouped by KCNJ5 mutational status. Prognostic factors of arterial stiffness and risk for hypertension at 12 months after adrenalectomy were analyzed after propensity score matching in a 1:1 ratio. After matching for age, sex and body mass index, 88 patients were divided equally into KCNJ5-mutant and non-mutant groups. KCNJ5 mutational status was not an independent variable in either the generalized estimating equation model (p = 0.147) or the percentage change of brachial-ankle pulse wave velocity (p = 0.106). The generalized additive model smoothing plot showed that aldosterone-producing adenoma patients who carried the KCNJ5 mutation and were aged between 37 and 60 may have a hypertension recovery advantage. According to our observations during a 12-month follow-up after adrenalectomy, KCNJ5 mutational status was not associated with improvement in arterial stiffness.
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Affiliation(s)
- Chia-Hui Chang
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Taipei Tzu Chi Hospital, The Buddhist Medical Foundation, Taiwan.,Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taiwan
| | - Ya-Hui Hu
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Taipei Tzu Chi Hospital, The Buddhist Medical Foundation, Taiwan
| | - Yao-Chou Tsai
- Division of Urology, Department of Surgery, Taipei Tzu Chi Hospital, The Buddhist Medical Foundation, Taiwan
| | - Che-Hsiung Wu
- Division of Nephrology, Department of Internal Medicine, Taipei Tzu Chi Hospital, The Buddhist Medical Foundation, Taiwan
| | - Shuo-Meng Wang
- Division of Urology, Department of Surgery, National Taiwan University Hospital, Taiwan
| | - Lian-Yu Lin
- Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital, Taiwan
| | - Yen-Hung Lin
- Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital, Taiwan
| | - Fumitoshi Satoh
- Division of Clinical Hypertension, Endocrinology and Metabolism, Tohoku University, Graduate School of Medicine, Sendai, Japan
| | - Kwan-Dun Wu
- Division of Nephrology, Department of Internal Medicine, National Taiwan University Hospital, Taiwan
| | - Vin-Cent Wu
- Division of Nephrology, Department of Internal Medicine, National Taiwan University Hospital, Taiwan.,TAIPAI, Taiwan Primary Aldosteronism Investigation (TAIPAI) Study Group, Taiwan
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Sertedaki A, Markou A, Vlachakis D, Kossida S, Campanac E, Hoffman DA, De La Luz Sierra M, Xekouki P, Stratakis CA, Kaltsas G, Piaditis GP, Chrousos GP, Charmandari E. Functional characterization of two novel germline mutations of the KCNJ5 gene in hypertensive patients without primary aldosteronism but with ACTH-dependent aldosterone hypersecretion. Clin Endocrinol (Oxf) 2016; 85:845-851. [PMID: 27293068 PMCID: PMC5118167 DOI: 10.1111/cen.13132] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 05/03/2016] [Accepted: 06/10/2016] [Indexed: 11/28/2022]
Abstract
BACKGROUND Germline mutations of the KCNJ5 gene encoding Kir3·4, a member of the inwardly rectifying K+ channel, have been identified in 'normal' adrenal glands, patients with familial hyperaldosteronism (FH) type III, aldosterone-producing adenomas (APAs) and sporadic cases of primary aldosteronism (PA). OBJECTIVE To present two novel KCNJ5 gene mutations in hypertensive patients without PA, but with Adrenocorticotropic hormone (ACTH)-dependent aldosterone hypersecretion. DESIGN AND PATIENTS Two hypertensive patients without PA, who exhibited enhanced ACTH-dependent response of aldosterone secretion, underwent genetic testing for the presence of the CYP11B1/CYP11B2 chimeric gene and KCNJ5 gene mutations. Genomic DNA was isolated from peripheral white blood cells, and the exons of the entire coding regions of the above genes were amplified and sequenced. Electrophysiological studies were performed to determine the effect of identified mutation(s) on the membrane reversal potentials. Structural biology studies were also carried out. RESULTS Two novel germline heterozygous KCNJ5 mutations, p.V259M and p.Y348N, were detected in the two subjects. Electrophysiological studies showed that the Y348N mutation resulted in significantly less negative reversal potentials, suggesting loss of ion selectivity, while the V259M mutation did not affect the Kir3.4 current. In the mutated structural biology model, the N348 mutant resulted in significant loss of the ability for hydrogen bonding, while the M259 mutant was capable of establishing weaker interactions. The CYP11B1/CYP11B2 chimeric gene was not detected. CONCLUSIONS These findings expand on the clinical spectrum of phenotypes associated with KCNJ5 mutations and implicate these mutations in the pathogenesis of hypertension associated with increased aldosterone response to ACTH stimulation.
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Affiliation(s)
- Amalia Sertedaki
- Division of Endocrinology, Metabolism and Diabetes, First Department of Pediatrics, National and Kapodistrian University of Athens Medical School, ‘Aghia Sophia’ Children’s Hospital, Athens, Greece
| | - Athina Markou
- Department of Endocrinology and Diabetes Center, “G. Gennimatas” General Hospital, Athens, Greece
| | - Dimitrios Vlachakis
- Bioinformatics & Medical Informatics Team Biomedical Research Foundation of the Academy of Athens, 4 Soranou Efesiou Street, 11527 Athens, Greece
| | - Sophia Kossida
- Bioinformatics & Medical Informatics Team Biomedical Research Foundation of the Academy of Athens, 4 Soranou Efesiou Street, 11527 Athens, Greece
| | - Emilie Campanac
- Molecular Neurophysiology and Biophysics Section, Program in Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Dax A. Hoffman
- Molecular Neurophysiology and Biophysics Section, Program in Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Maria De La Luz Sierra
- Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892 USA
| | - Paraskevi Xekouki
- Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892 USA
| | - Constantine A. Stratakis
- Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892 USA
| | - Gregory Kaltsas
- Department of Pathophysiology, National and Kapodistrian University of Athens Medical School, ‘Laikon’ Hospital, Athens, Greece
| | - George P. Piaditis
- Department of Endocrinology and Diabetes Center, “G. Gennimatas” General Hospital, Athens, Greece
| | - George P. Chrousos
- Division of Endocrinology, Metabolism and Diabetes, First Department of Pediatrics, National and Kapodistrian University of Athens Medical School, ‘Aghia Sophia’ Children’s Hospital, Athens, Greece
| | - Evangelia Charmandari
- Division of Endocrinology, Metabolism and Diabetes, First Department of Pediatrics, National and Kapodistrian University of Athens Medical School, ‘Aghia Sophia’ Children’s Hospital, Athens, Greece
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Spät A, Hunyady L, Szanda G. Signaling Interactions in the Adrenal Cortex. Front Endocrinol (Lausanne) 2016; 7:17. [PMID: 26973596 PMCID: PMC4770035 DOI: 10.3389/fendo.2016.00017] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 02/11/2016] [Indexed: 11/30/2022] Open
Abstract
The major physiological stimuli of aldosterone secretion are angiotensin II (AII) and extracellular K(+), whereas cortisol production is primarily regulated by corticotropin (ACTH) in fasciculata cells. AII triggers Ca(2+) release from internal stores that is followed by store-operated and voltage-dependent Ca(2+) entry, whereas K(+)-evoked depolarization activates voltage-dependent Ca(2+) channels. ACTH acts primarily through the formation of cAMP and subsequent protein phosphorylation by protein kinase A. Both Ca(2+) and cAMP facilitate the transfer of cholesterol to mitochondrial inner membrane. The cytosolic Ca(2+) signal is transferred into the mitochondrial matrix and enhances pyridine nucleotide reduction. Increased formation of NADH results in increased ATP production, whereas that of NADPH supports steroid production. In reality, the control of adrenocortical function is a lot more sophisticated with second messengers crosstalking and mutually modifying each other's pathways. Cytosolic Ca(2+) and cGMP are both capable of modifying cAMP metabolism, while cAMP may enhance Ca(2+) release and voltage-activated Ca(2+) channel activity. Besides, mitochondrial Ca(2+) signal brings about cAMP formation within the organelle and this further enhances aldosterone production. Maintained aldosterone and cortisol secretion are optimized by the concurrent actions of Ca(2+) and cAMP, as exemplified by the apparent synergism of Ca(2+) influx (inducing cAMP formation) and Ca(2+) release during response to AII. Thus, cross-actions of parallel signal transducing pathways are not mere intracellular curiosities but rather substantial phenomena, which fine-tune the biological response. Our review focuses on these functionally relevant interactions between the Ca(2+) and the cyclic nucleotide signal transducing pathways hitherto described in the adrenal cortex.
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Affiliation(s)
- András Spät
- Department of Physiology, Semmelweis University Medical School, Budapest, Hungary
- Laboratory of Molecular Physiology, Hungarian Academy of Sciences, Budapest, Hungary
- *Correspondence: András Spät,
| | - László Hunyady
- Department of Physiology, Semmelweis University Medical School, Budapest, Hungary
- Laboratory of Molecular Physiology, Hungarian Academy of Sciences, Budapest, Hungary
| | - Gergő Szanda
- Department of Physiology, Semmelweis University Medical School, Budapest, Hungary
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Okubo Y, Sato Y, Nakasone Y, Shirotori K, Oguchi K, Matsushita T, Nishikawa T, Yamazaki Y, Sasano H, Komatsu M, Yamauchi K, Aizawa T. Extraordinarily high aldosterone, 901.0 ng/dL, in a patient with primary aldosteronism: an insight into the underlying mechanism. Endocr J 2016; 63:127-33. [PMID: 26549209 DOI: 10.1507/endocrj.ej15-0398] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
A 43-yr-old hypertensive male was admitted due to hypokalemia (1.8 mEq/L) and renal dysfunction (eGFR, 20.0 mL/min/1.73 m2). His plasma aldosterone was 901.0 ng/dL, plasma renin activity 5.7 ng/mL/hr, and aldosterone/renin activity ratio 158. Angiotensin II (AII) was 0.7 pg/mL, ACTH <1.0 pg/mL, and cortisol 21.6 μg/dL. Liquid chromatography-tandem mass spectrometry analysis showed that aldosterone (104 times the control) as well as its precursors were significantly elevated in the patient's plasma. A left adrenal (4-cm-diameter) tumor with 131I-Adosterol uptake was found and removed. Four days later, plasma aldosterone and renin activity had dropped to 7.73 ng/dL and 1.6 ng/mL/hr, respectively. However, they rose to 24.0 ng/dL and 10.9 ng/mL/hr, respectively, by Day 102. Nevertheless, magnetic resonance angiography found no evidence of a renovascular lesion. The tumor was a benign adrenocortical adenoma composed predominantly of clear cells positive for 17α-hydroxylase, [hydroxy-delta-5-steroid dehydrogenase, 3 beta- and steroid delta-isomerases], and aldosterone synthase. A quantitative real-time polymerase chain reaction analysis of the tumor cells revealed that expression of the gene encoding aldosterone synthase was 85 times the control level. In addition, the tumor cells harbored G151R mutation of the inward rectifying potassium channel subfamily j, member 5 gene. The striking overexpression of aldosterone synthase by the tumor cells was considered the primary mechanism for the extravagant overproduction of aldosterone in this case. This overexpression may have resulted from integration of signals from AII and forced membrane depolarization due to the potassium channel mutation.
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Affiliation(s)
- Yosuke Okubo
- Division of Diabetes, Endocrinology and Metabolism, Department of Internal Medicine, Shinshu University School of Medicine, Matsumoto, Japan
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Abstract
Five syndromes share predominantly hyperplastic glands with a primary excess of hormones: neonatal severe primary hyperparathyroidism, from homozygous mutated CASR, begins severely in utero; congenital non-autoimmune thyrotoxicosis, from mutated TSHR, varies from severe with fetal onset to mild with adult onset; familial male-limited precocious puberty, from mutated LHR, expresses testosterone oversecretion in young boys; hereditary ovarian hyperstimulation syndrome, from mutated FSHR, expresses symptomatic systemic vascular permeabilities during pregnancy; and familial hyperaldosteronism type IIIA, from mutated KCNJ5, presents in young children with hypertension and hypokalemia. The grouping of these five syndromes highlights predominant hyperplasia as a stable tissue endpoint and as their tissue stage for all of the hormone excess. Comparisons were made among this and two other groups of syndromes, forming a continuum of gland staging: predominant oversecretions express little or no hyperplasia; predominant hyperplasias express little or no neoplasia; and predominant neoplasias express nodules, adenomas, or cancers. Hyperplasias may progress (5 of 5) to neoplastic stages while predominant oversecretions rarely do (1 of 6; frequencies differ P<0.02). Hyperplasias do not show tumor multiplicity (0 of 5) unlike neoplasias that do (13 of 19; P<0.02). Hyperplasias express mutation of a plasma membrane-bound sensor (5 of 5), while neoplasias rarely do (3 of 14; P<0.002). In conclusion, the multiple distinguishing themes within the hyperplasias establish a robust pathophysiology. It has the shared and novel feature of mutant sensors in the plasma membrane, suggesting that these are major contributors to hyperplasia.
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Affiliation(s)
- Stephen J Marx
- Genetics and Endocrinology SectionNational Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Building 10, Room 9C-103, Bethesda, Maryland 20892, USA
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Abstract
Primary aldosteronism is the most common cause of secondary hypertension, incurring significant cardiovascular morbidity and mortality. Our understanding of this disease has evolved substantially during the past decade. Recently, the molecular basis of primary aldosteronism has begun to be unraveled, with the discovery of mutations in potassium channel (KCNJ5), ATPases (ATP1A1, ATP2B3), and calcium channel (CACNA1D), and aberrant Wnt/β-catenin signaling. The most recent data suggest that 95% of cases are sporadic, whereas 5% of cases are hereditary. Pathologic correlates of primary aldosteronism include adrenal cortical hyperplasia, adenoma, and carcinoma. Although the most common clinical presentation is bilateral adrenal cortical hyperplasia, this entity is usually treated medically. Therefore, in the setting of primary aldosteronism, surgical pathologists are most commonly exposed to adrenocortical adenomas and the odd occasional carcinoma. This review provides an update on the current knowledge of primary aldosteronism and discusses the clinicopathologic correlations of this important disease.
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Affiliation(s)
| | - Ozgur Mete
- From the Department of Pathology, University Health Network
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Al-Salameh A, Cohen R, Desailloud R. Overview of the genetic determinants of primary aldosteronism. APPLICATION OF CLINICAL GENETICS 2014; 7:67-79. [PMID: 24817817 PMCID: PMC4012345 DOI: 10.2147/tacg.s45620] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Primary aldosteronism is the most common cause of secondary hypertension. The syndrome accounts for 10% of all cases of hypertension and is primarily caused by bilateral adrenal hyperplasia or aldosterone-producing adenoma. Over the last few years, the use of exome sequencing has significantly improved our understanding of this syndrome. Somatic mutations in the KCNJ5, ATP1A1, ATP2B3 or CACNA1D genes are present in more than half of all cases of aldosterone-producing adenoma (~40%, ~6%, ~1% and ~8%, respectively). Germline gain-of-function mutations in KCNJ5 are now known to cause familial hyperaldosteronism type III, and an additional form of genetic hyperaldosteronism has been reported in patients with germline mutations in CACNA1D. These genes code for channels that control ion homeostasis across the plasma membrane of zona glomerulosa cells. Moreover, all these mutations modulate the same pathway, in which elevated intracellular calcium levels lead to aldosterone hyperproduction and (in some cases) adrenal cell proliferation. From a clinical standpoint, the discovery of these mutations has potential implications for patient management. The mutated channels could be targeted by drugs, in order to control hormonal and overgrowth-related manifestations. Furthermore, some of these mutations are associated with high cell turnover and may be amenable to diagnosis via the sequencing of cell-free (circulating) DNA. However, genotype-phenotype correlations in patients harboring these mutations have yet to be characterized. Despite this recent progress, much remains to be done to elucidate the yet unknown mechanisms underlying sporadic bilateral adrenal hyperplasia.
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Affiliation(s)
- Abdallah Al-Salameh
- Service de Diabétologie, Endocrinologie et Maladies Métaboliques, Centre Hospitalier de Creil, Creil, France
| | - Régis Cohen
- Service d'Endocrinologie, Centre Hospitalier de Saint-Denis, Saint-Denis, France
| | - Rachel Desailloud
- Service d'Endocrinologie, Diabétologie et Nutrition, Centre Hospitalier Universitaire d'Amiens, Amiens, France
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Affiliation(s)
- Dr Morag J Young
- Prince Henry's Institute of Medical Research; Clayton
- Department of Physiology and Medicine; Monash University; Clayton
| | - Peter J Fuller
- Prince Henry's Institute of Medical Research; Clayton
- Department of Endocrinology Southern Health Clayton; Woolloongabba
| | - Michael Stowasser
- Endocrine Hypertension Research Centre University of Queensland, School of Medicine Princess Alexandra Hospital; Woolloongabba
| | - A Susie Mihailidou
- Department of Cardiology & Kolling Institute of Medical Research, Royal North Shore Hospital; St Leonards Australia
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