Effect of KCNJ5 mutations on gene expression in aldosterone-producing adenomas and adrenocortical cells.
BACKGROUND
Primary aldosteronism is a heterogeneous disease that includes both sporadic and familial forms. A point mutation in the KCNJ5 gene is responsible for familial hyperaldosteronism type III. Somatic mutations in KCNJ5 also occur in sporadic aldosterone producing adenomas (APA).


OBJECTIVE
The objective of the study was to define the effect of the KCNJ5 mutations on gene expression and aldosterone production using APA tissue and human adrenocortical cells.


METHODS
A microarray analysis was used to compare the transcriptome profiles of female-derived APA samples with and without KCNJ5 mutations and HAC15 adrenal cells overexpressing either mutated or wild-type KCNJ5. Real-time PCR validated a set of differentially expressed genes. Immunohistochemical staining localized the KCNJ5 expression in normal adrenals and APA.


RESULTS
We report a 38% (18 of 47) prevalence of KCNJ5 mutations in APA. KCNJ5 immunostaining was highest in the zona glomerulosa of NA and heterogeneous in APA tissue, and KCNJ5 mRNA was 4-fold higher in APA compared with normal adrenals (P < 0.05). APA with and without KCNJ5 mutations displayed slightly different gene expression patterns, notably the aldosterone synthase gene (CYP11B2) was more highly expressed in APA with KCNJ5 mutations. Overexpression of KCNJ5 mutations in HAC15 increased aldosterone production and altered expression of 36 genes by greater than 2.5-fold (P < 0.05). Real-time PCR confirmed increases in CYP11B2 and its transcriptional regulator, NR4A2.


CONCLUSIONS
KCNJ5 mutations are prevalent in APA, and our data suggest that these mutations increase expression of CYP11B2 and NR4A2, thus increasing aldosterone production.
Department of Physiology, the Institute of Molecular Medicine and Genetics, Georgia Health Sciences University, Augusta, Georgia 30912, USA.
Silvia
S
Monticone
Namita G
NG
Hattangady
Koshiro
K
Nishimoto
Franco
F
Mantero
Beatrice
B
Rubin
Maria Verena
MV
Cicala
Raffaele
R
Pezzani
Richard J
RJ
Auchus
Hans K
HK
Ghayee
Hirotaka
H
Shibata
Isao
I
Kurihara
Tracy A
TA
Williams
Judith G
JG
Giri
Roni J
RJ
Bollag
Michael A
MA
Edwards
Carlos M
CM
Isales
William E
WE
Rainey
D000236:Adenoma / Q000235:genetics* / Q000378:metabolism; D000302:Adrenal Cortex / Q000166:cytology / Q000378:metabolism*; D000310:Adrenal Gland Neoplasms / Q000235:genetics* / Q000378:metabolism; D000450:Aldosterone / Q000096:biosynthesis*; D045744:Cell Line, Tumor; D005260:Female; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels / Q000235:genetics*; D020869:Gene Expression Profiling; D006801:Humans; D009154:Mutation
D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels; C484274:KCNJ5 protein, human; D000450:Aldosterone