Mutated KCNJ5 activates the acute and chronic regulatory steps in aldosterone production.
Somatic and germline mutations in the inward-rectifying K(+) channel (KCNJ5) are a common cause of primary aldosteronism (PA) in aldosterone-producing adenoma and familial hyperaldosteronism type III, respectively. Dysregulation of adrenal cell calcium signaling represents one mechanism for mutated KCNJ5 stimulation of aldosterone synthase (CYP11B2) expression and aldosterone production. However, the mechanisms stimulating acute and chronic production of aldosterone by mutant KCNJ5 have not been fully characterized. Herein, we defined the effects of the T158A KCNJ5 mutation (KCNJ5(T158A)) on acute and chronic regulation of aldosterone production using an adrenal cell line with a doxycycline-inducible KCNJ5(T158A) gene (HAC15-TRE-KCNJ5(T158A)). Doxycycline incubation caused a time-dependent increase in KCNJ5(T158A) and CYP11B2 mRNA and protein levels. Electrophysiological analyses confirm the loss of inward rectification and increased Na(+) permeability in KCNJ5(T158A)-expressing cells. KCNJ5(T158A) expression also led to the activation of CYP11B2 transcriptional regulators, NURR1 and ATF2. Acutely, KCNJ5(T158A) stimulated the expression of total and phosphorylated steroidogenic acute regulatory protein (StAR). KCNJ5(T158A) expression increased the synthesis of aldosterone and the hybrid steroids 18-hydroxycortisol and 18-oxocortisol, measured with liquid chromatography-tandem mass spectrometry (LC-MS/MS). All of these stimulatory effects of KCNJ5(T158A) were inhibited by the L-type Ca(2+) channel blocker, verapamil. Overall, KCNJ5(T158A)increases CYP11B2 expression and production of aldosterone, corticosterone and hybrid steroids by upregulating both acute and chronic regulatory events in aldosterone production, and verapamil blocks KCNJ5(T158A)-mediated pathways leading to aldosterone production.
Department of Internal MedicineDivision of Metabolism, Endocrinology and Diabetes, University of Michigan, Ann Arbor, Michigan, USA.
Namita G
NG
Hattangady
Department of Internal MedicineDivision of Metabolism, Endocrinology and Diabetes, University of Michigan, Ann Arbor, Michigan, USA Department of PharmacologyUniversity of Michigan, Ann Arbor, Michigan, USA.
Shigehiro
S
Karashima
Department of Internal MedicineDivision of Metabolism, Endocrinology and Diabetes, University of Michigan, Ann Arbor, Michigan, USA.
Lucy
L
Yuan
Center for Arrhythmia ResearchUniversity of Michigan, Ann Arbor, Michigan, USA.
Daniela
D
Ponce-Balbuena
Center for Arrhythmia ResearchUniversity of Michigan, Ann Arbor, Michigan, USA.
José
J
Jalife
G. V. (Sonny) Montgomery VA Medical Center and Department of MedicineUniversity of Mississippi Medical Center, Jackson, Mississippi, USA.
Celso E
CE
Gomez-Sanchez
Department of Internal MedicineDivision of Metabolism, Endocrinology and Diabetes, University of Michigan, Ann Arbor, Michigan, USA Department of PharmacologyUniversity of Michigan, Ann Arbor, Michigan, USA.
Richard J
RJ
Auchus
Department of Internal MedicineDivision of Metabolism, Endocrinology and Diabetes, University of Michigan, Ann Arbor, Michigan, USA Department of Molecular and Integrative PhysiologyUniversity of Michigan, Ann Arbor, Michigan, USA.
William E
WE
Rainey
Department of Internal MedicineDivision of Metabolism, Endocrinology and Diabetes, University of Michigan, Ann Arbor, Michigan, USA telse@umich.edu.
Tobias
T
Else
D000311:Adrenal Glands / Q000378:metabolism; D000450:Aldosterone / Q000096:biosynthesis*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D045744:Cell Line, Tumor; D019405:Cytochrome P-450 CYP11B2 / Q000235:genetics / Q000378:metabolism; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D005786:Gene Expression Regulation / Q000187:drug effects; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D009154:Mutation; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013256:Steroids / Q000096:biosynthesis; D014158:Transcription, Genetic; D014161:Transduction, Genetic
D002121:Calcium Channel Blockers; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels; C484274:KCNJ5 protein, human; D012333:RNA, Messenger; D013256:Steroids; D000450:Aldosterone; D019405:Cytochrome P-450 CYP11B2
KCNJ5 mutations; adrenal; aldosterone; primary aldosteronism (PA)