Pathogenesis of Adrenal Aldosterone-Producing Adenomas Carrying Mutations of the Na(+)/K(+)-ATPase
| Autor: | Julia Stindl, Christina Sterner, Philipp Tauber, Ines Tegtmeier, Sascha Bandulik, Richard Warth |
|---|---|
| Rok vydání: | 2015 |
| Předmět: |
medicine.medical_specialty
Patch-Clamp Techniques Sodium-Hydrogen Exchangers Intracellular pH ATPase Biology chemistry.chemical_compound Endocrinology Cytosol Internal medicine Cell Line Tumor medicine Adrenocortical Carcinoma Humans Patch clamp Na+/K+-ATPase Aldosterone Adrenal cortex Reverse Transcriptase Polymerase Chain Reaction Depolarization Hydrogen-Ion Concentration Adrenal Cortex Neoplasms Sodium–hydrogen antiporter medicine.anatomical_structure chemistry Adrenocortical Adenoma Mutation biology.protein Adrenal Cortex Calcium Sodium-Potassium-Exchanging ATPase |
| Zdroj: | Endocrinology. 156(12) |
| ISSN: | 1945-7170 |
| Popis: | Aldosterone-producing adenoma (APA) is a major cause of primary aldosteronism, leading to secondary hypertension. Somatic mutations in the gene for the α1 subunit of the Na(+)/K(+)-ATPase were found in about 6% of APAs. APA-related α1 subunit of the Na(+)/K(+)-ATPase mutations lead to a loss of the pump function of the Na(+)/K(+)-ATPase, which is believed to result in membrane depolarization and Ca(2+)-dependent stimulation of aldosterone synthesis in adrenal cells. In addition, H(+) and Na(+) leak currents via the mutant Na(+)/K(+)-ATPase were suggested to contribute to the phenotype. The aim of this study was to investigate the cellular pathophysiology of adenoma-associated Na(+)/K(+)-ATPase mutants (L104R, V332G, G99R) in adrenocortical NCI-H295R cells. The expression of these Na(+)/K(+)-ATPase mutants depolarized adrenal cells and stimulated aldosterone secretion. However, an increase of basal cytosolic Ca(2+) levels in Na(+)/K(+)-ATPase mutant cells was not detectable, and stimulation with high extracellular K(+) hardly increased Ca(2+) levels in cells expressing L104R and V332G mutant Na(+)/K(+)-ATPase. Cytosolic pH measurements revealed an acidification of L104R and V332G mutant cells, despite an increased activity of the Na(+)/H(+) exchanger. The possible contribution of cellular acidification to the hypersecretion of aldosterone was supported by the observation that aldosterone secretion of normal adrenocortical cells was stimulated by acetate-induced acidification. Taken together, mutations of the Na(+)/K(+)-ATPase depolarize adrenocortical cells, disturb the K(+) sensitivity, and lower intracellular pH but, surprisingly, do not induce an overt increase of intracellular Ca(2+). Probably, the autonomous aldosterone secretion is caused by the concerted action of several pathological signaling pathways and incomplete cellular compensation. |
| Databáze: | OpenAIRE |
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