Novel KCNJ5 mutations in sporadic aldosterone-producing adenoma reduce Kir3.4 membrane abundance

Chih Jen Cheng, Chih Chien Sung, Sheng Tang Wu, Yu Chun Lin, Huey Kang Sytwu, Chou Long Huang, Shih Hua Lin

Research output: Contribution to journalArticle

Abstract

CONTEXT: Aldosterone-producing adenoma (APA) has been linked to mutations in the KCNJ5 gene encoding the inward-rectifying potassium (K(+)) Kir3.4 channel. These mutations abolish the K(+) selectivity of Kir3.4 and, consequently, cause sodium (Na(+)) leak, depolarized membrane potential, and nonsuppressible aldosterone secretion.

OBJECTIVE: Our objective was to investigate KCNJ5 mutations in patients with sporadic APA and the role of endogenous Kir3.4 in human adrenocortical cells.

DESIGN: We screened the KCNJ5 gene from the adrenal adenomas of 69 Chinese patients with sporadic APA and functionally characterized novel Kir3.4 mutations.

RESULTS: Thirty-seven percent (26 of 69) of our APA patients carried heterozygous somatic mutations in the KCNJ5 gene. Besides the most common G151R and L168R mutations, we identified a previously uncharacterized E145Q mutation and 2 novel mutations (R115W and E246G) in 6 patients. The E145Q mutant conducted a barium-insensitive Na(+)-leak current. The R115W and E246G mutants preserved barium-sensitive, K(+)-selective and Gβγ-activatable Kir3.4 currents, which were ∼30% and ∼15% of wild-type current, respectively. Biotinylation assays revealed markedly reduced membrane abundance of R115W and E246G mutants. All Kir3.4 mutants exerted dominant-negative effects on wild-type channels. Kir3.4 protein expression in APAs with the novel KCNJ5 mutation was significantly lower than those in APAs with wild-type KCNJ5 or Na(+)-leak KCNJ5 mutations. Inhibition of endogenous Kir3.4 by tertiapin-Q significantly depolarized membrane potential and increased CYP11B2 expression in human adrenocortical cells.

CONCLUSION: Besides Na(+)-leak mutations, novel KCNJ5 mutations causing a reduction of surface and total abundance of Kir3.4 are also associated with sporadic APA. Basal Kir3.4 current is important to maintaining normal resting membrane potential and suppressing aldosterone synthesis in human adrenocortical cells.

Original languageEnglish (US)
Pages (from-to)E155-E163
JournalThe Journal of clinical endocrinology and metabolism
Volume100
Issue number1
DOIs
StatePublished - Jan 1 2015

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Aldosterone
Adenoma
Membranes
Mutation
Barium
Membrane Potentials
Genes
Cytochrome P-450 CYP11B2
Gene encoding
G Protein-Coupled Inwardly-Rectifying Potassium Channels
Assays
Potassium
Biotinylation
Sodium
Proteins

ASJC Scopus subject areas

  • Medicine(all)

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Novel KCNJ5 mutations in sporadic aldosterone-producing adenoma reduce Kir3.4 membrane abundance. / Cheng, Chih Jen; Sung, Chih Chien; Wu, Sheng Tang; Lin, Yu Chun; Sytwu, Huey Kang; Huang, Chou Long; Lin, Shih Hua.

In: The Journal of clinical endocrinology and metabolism, Vol. 100, No. 1, 01.01.2015, p. E155-E163.

Research output: Contribution to journalArticle

Cheng, Chih Jen ; Sung, Chih Chien ; Wu, Sheng Tang ; Lin, Yu Chun ; Sytwu, Huey Kang ; Huang, Chou Long ; Lin, Shih Hua. / Novel KCNJ5 mutations in sporadic aldosterone-producing adenoma reduce Kir3.4 membrane abundance. In: The Journal of clinical endocrinology and metabolism. 2015 ; Vol. 100, No. 1. pp. E155-E163.
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abstract = "CONTEXT: Aldosterone-producing adenoma (APA) has been linked to mutations in the KCNJ5 gene encoding the inward-rectifying potassium (K(+)) Kir3.4 channel. These mutations abolish the K(+) selectivity of Kir3.4 and, consequently, cause sodium (Na(+)) leak, depolarized membrane potential, and nonsuppressible aldosterone secretion.OBJECTIVE: Our objective was to investigate KCNJ5 mutations in patients with sporadic APA and the role of endogenous Kir3.4 in human adrenocortical cells.DESIGN: We screened the KCNJ5 gene from the adrenal adenomas of 69 Chinese patients with sporadic APA and functionally characterized novel Kir3.4 mutations.RESULTS: Thirty-seven percent (26 of 69) of our APA patients carried heterozygous somatic mutations in the KCNJ5 gene. Besides the most common G151R and L168R mutations, we identified a previously uncharacterized E145Q mutation and 2 novel mutations (R115W and E246G) in 6 patients. The E145Q mutant conducted a barium-insensitive Na(+)-leak current. The R115W and E246G mutants preserved barium-sensitive, K(+)-selective and Gβγ-activatable Kir3.4 currents, which were ∼30{\%} and ∼15{\%} of wild-type current, respectively. Biotinylation assays revealed markedly reduced membrane abundance of R115W and E246G mutants. All Kir3.4 mutants exerted dominant-negative effects on wild-type channels. Kir3.4 protein expression in APAs with the novel KCNJ5 mutation was significantly lower than those in APAs with wild-type KCNJ5 or Na(+)-leak KCNJ5 mutations. Inhibition of endogenous Kir3.4 by tertiapin-Q significantly depolarized membrane potential and increased CYP11B2 expression in human adrenocortical cells.CONCLUSION: Besides Na(+)-leak mutations, novel KCNJ5 mutations causing a reduction of surface and total abundance of Kir3.4 are also associated with sporadic APA. Basal Kir3.4 current is important to maintaining normal resting membrane potential and suppressing aldosterone synthesis in human adrenocortical cells.",
author = "Cheng, {Chih Jen} and Sung, {Chih Chien} and Wu, {Sheng Tang} and Lin, {Yu Chun} and Sytwu, {Huey Kang} and Huang, {Chou Long} and Lin, {Shih Hua}",
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T1 - Novel KCNJ5 mutations in sporadic aldosterone-producing adenoma reduce Kir3.4 membrane abundance

AU - Cheng, Chih Jen

AU - Sung, Chih Chien

AU - Wu, Sheng Tang

AU - Lin, Yu Chun

AU - Sytwu, Huey Kang

AU - Huang, Chou Long

AU - Lin, Shih Hua

PY - 2015/1/1

Y1 - 2015/1/1

N2 - CONTEXT: Aldosterone-producing adenoma (APA) has been linked to mutations in the KCNJ5 gene encoding the inward-rectifying potassium (K(+)) Kir3.4 channel. These mutations abolish the K(+) selectivity of Kir3.4 and, consequently, cause sodium (Na(+)) leak, depolarized membrane potential, and nonsuppressible aldosterone secretion.OBJECTIVE: Our objective was to investigate KCNJ5 mutations in patients with sporadic APA and the role of endogenous Kir3.4 in human adrenocortical cells.DESIGN: We screened the KCNJ5 gene from the adrenal adenomas of 69 Chinese patients with sporadic APA and functionally characterized novel Kir3.4 mutations.RESULTS: Thirty-seven percent (26 of 69) of our APA patients carried heterozygous somatic mutations in the KCNJ5 gene. Besides the most common G151R and L168R mutations, we identified a previously uncharacterized E145Q mutation and 2 novel mutations (R115W and E246G) in 6 patients. The E145Q mutant conducted a barium-insensitive Na(+)-leak current. The R115W and E246G mutants preserved barium-sensitive, K(+)-selective and Gβγ-activatable Kir3.4 currents, which were ∼30% and ∼15% of wild-type current, respectively. Biotinylation assays revealed markedly reduced membrane abundance of R115W and E246G mutants. All Kir3.4 mutants exerted dominant-negative effects on wild-type channels. Kir3.4 protein expression in APAs with the novel KCNJ5 mutation was significantly lower than those in APAs with wild-type KCNJ5 or Na(+)-leak KCNJ5 mutations. Inhibition of endogenous Kir3.4 by tertiapin-Q significantly depolarized membrane potential and increased CYP11B2 expression in human adrenocortical cells.CONCLUSION: Besides Na(+)-leak mutations, novel KCNJ5 mutations causing a reduction of surface and total abundance of Kir3.4 are also associated with sporadic APA. Basal Kir3.4 current is important to maintaining normal resting membrane potential and suppressing aldosterone synthesis in human adrenocortical cells.

AB - CONTEXT: Aldosterone-producing adenoma (APA) has been linked to mutations in the KCNJ5 gene encoding the inward-rectifying potassium (K(+)) Kir3.4 channel. These mutations abolish the K(+) selectivity of Kir3.4 and, consequently, cause sodium (Na(+)) leak, depolarized membrane potential, and nonsuppressible aldosterone secretion.OBJECTIVE: Our objective was to investigate KCNJ5 mutations in patients with sporadic APA and the role of endogenous Kir3.4 in human adrenocortical cells.DESIGN: We screened the KCNJ5 gene from the adrenal adenomas of 69 Chinese patients with sporadic APA and functionally characterized novel Kir3.4 mutations.RESULTS: Thirty-seven percent (26 of 69) of our APA patients carried heterozygous somatic mutations in the KCNJ5 gene. Besides the most common G151R and L168R mutations, we identified a previously uncharacterized E145Q mutation and 2 novel mutations (R115W and E246G) in 6 patients. The E145Q mutant conducted a barium-insensitive Na(+)-leak current. The R115W and E246G mutants preserved barium-sensitive, K(+)-selective and Gβγ-activatable Kir3.4 currents, which were ∼30% and ∼15% of wild-type current, respectively. Biotinylation assays revealed markedly reduced membrane abundance of R115W and E246G mutants. All Kir3.4 mutants exerted dominant-negative effects on wild-type channels. Kir3.4 protein expression in APAs with the novel KCNJ5 mutation was significantly lower than those in APAs with wild-type KCNJ5 or Na(+)-leak KCNJ5 mutations. Inhibition of endogenous Kir3.4 by tertiapin-Q significantly depolarized membrane potential and increased CYP11B2 expression in human adrenocortical cells.CONCLUSION: Besides Na(+)-leak mutations, novel KCNJ5 mutations causing a reduction of surface and total abundance of Kir3.4 are also associated with sporadic APA. Basal Kir3.4 current is important to maintaining normal resting membrane potential and suppressing aldosterone synthesis in human adrenocortical cells.

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