Kuppusamy, Maniselvan and Caroccia, Brasilina and Stindl, Julia and Bandulik, Sascha and Lenzini, Livia and Gioco, Francesca and Fishman, Veniamin and Zanotti, Giuseppe and Gomez-Sanchez, Celso and Bader, Michael and Warth, Richard and Rossi, Gian Paolo (2014) A Novel KCNJ5-insT149 Somatic Mutation Close to, but Outside, the Selectivity Filter Causes Resistant Hypertension by Loss of Selectivity for Potassium. JOURNAL OF CLINICAL ENDOCRINOLOGY & METABOLISM, 99 (9). E1765-E1773. ISSN 0021-972X, 1945-7197
Full text not available from this repository. (Request a copy)Abstract
Context: Understanding the function of the KCNJ5 potassium channel through characterization of naturally occurring novel mutations is key for dissecting the mechanism(s) of autonomous aldosterone secretion in primary aldosteronism. Objective: We sought for such novel KCNJ5 channel mutations in a large database of patients with aldosterone-producing adenomas (APAs). Methods: We discovered a novel somatic c.446insAAC insertion, resulting in the mutant protein KCNJ5-insT149, in a patient with severe drug-resistant hypertension among 195 consecutive patients with a conclusive diagnosis of APA, 24.6% of whom showed somatic KCNJ5 mutations. By site-directed mutagenesis, we created the mutated cDNA that was transfected, along with KCNJ3 cDNA, in mammalian cells. We also localized CYP11B2 in the excised adrenal gland with immunohistochemistry and immunofluorescence using an antibody specific to human CYP11B2. Whole-cell patch clamp recordings, CYP11B2 mRNA, aldosterone measurement, and molecular modeling were performed to characterize the novel KCNJ5-insT149 mutation. Results: Compared with wild-type and mock-transfected adrenocortical cells, HAC15 cells expressing the mutant KCNJ5 showed increased CYP11B2 expression and aldosterone secretion. Mammalian cells expressing the mutated KCNJ5-insT149 channel exhibited a strong Na+ inward current and, in parallel, asubstantial rise in intracellular Ca2+, caused by activation of voltage-gated Ca2+ channels and reduced Ca2+ elimination by Na+/Ca2+ exchangers, as well as an increased production of aldosterone. Conclusions: This novel mutation shows pathological Na+ permeability, membrane depolarization, raised cytosolic Ca2+, and increased aldosterone synthesis. Hence, a novel KCNJ5 channelopathy located after the pore alpha-helix preceding the selectivity filter causes constitutive secretion of aldosterone with ensuing resistant hypertension in a patient with a small APA.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | ALDOSTERONE-PRODUCING ADENOMAS; KCNJ5 MUTATIONS; GENE-EXPRESSION; CHANNEL; PREVALENCE; ATP1A1; ACID; |
| Subjects: | 500 Science > 570 Life sciences |
| Divisions: | Biology, Preclinical Medicine > Institut für Physiologie > Prof. Dr. Richard Warth |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 27 Aug 2019 12:51 |
| Last Modified: | 27 Aug 2019 12:51 |
| URI: | https://pred.uni-regensburg.de/id/eprint/9633 |
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