Novel Insertion Mutation in KCNJ5 Channel Produces Constitutive Aldosterone Release From H295R Cells
Autor: | Ruth D. Murrell-Lagnado, Andrew J. Thompson, Kevin M. O'Shaughnessy, Richard D. Gordon, Nichola Figg, Iris Hardege, Michael Stowasser, Shengxin Xu |
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Rok vydání: | 2015 |
Předmět: |
Male
medicine.medical_specialty Angiotensins Xenopus DNA Mutational Analysis Molecular Sequence Data Mutant medicine.disease_cause Cell Line chemistry.chemical_compound Endocrinology Internal medicine KCNJ5 medicine Animals Humans Amino Acid Sequence Insertion Aldosterone Molecular Biology Original Research Mutation Base Sequence biology Protein Stability Wild type General Medicine Middle Aged Angiotensin II Molecular biology Potassium channel Electrophysiological Phenomena Mutagenesis Insertional G Protein-Coupled Inwardly-Rectifying Potassium Channels chemistry biology.protein |
Zdroj: | Molecular Endocrinology. 29:1522-1530 |
ISSN: | 1944-9917 0888-8809 |
Popis: | Primary aldosteronism accounts for 5%-10% of hypertension and in a third of cases is caused by autonomous aldosterone production by adenomas (APA). Somatic mutations in the potassium channel encoded by KCNJ5 have been detected in surgically removed APAs. To better understand the role of these mutations, we resequenced the KCNJ5 channel in a large Australian primary aldosteronism cohort. KCNJ5 mutations were detected in 37 APAs (45% of the cohort), including previously reported E145Q (n = 3), G151R (n = 20), and L168R (n = 13) mutations. In addition, we found a novel 12-bp in-frame insertion mutation (c.414-425dupGCTTTCCTGTTC, A139_F142dup) that duplicates the AFLF sequence in the pore helix upstream of the selectivity filter. Expressed in Xenopus oocytes, the A139_F142dup mutation depolarized the oocytes and produced a G-protein-sensitive Na(+) current with altered K(+) selectivity and loss of inward rectification but retained Ba(2+) sensitivity. Transfected into H295R cells, A139_F142dup increased basal aldosterone release 2.3-fold over the wild type. This was not increased further by incubation with angiotensin II. Although the A139_F142dup mutant trafficked to the plasma membrane of H295R cells, it showed reduced tetramer stability and surface expression compared with the wild-type channel. This study confirms the frequency of somatic KCNJ5 mutations in APAs and the novel mutation identified (A139_F142dup) extend the phenotypic range of the known KCNJ5 APA mutations. Being located in the pore helix, it is upstream of the previously reported mutations and shares some features in common with selectivity filter mutants but additionally demonstrates insensitivity to angiotensin II and decreased channel stability. |
Databáze: | OpenAIRE |
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