VSNL1 is upregulated in aldosterone producing adenomas with KCNJ5 mutations and protects from calcium-induced apoptosis
S. Monticone1, V. Crudo1, J. Burrello1, M. Galmozzi1, R. Warth2, F. Veglio1, P. Mulatero1 & T. Williams1
Visinin-like 1 (VSNL1) is upregulated in aldosterone-producing adenomas (APA) compared to normal adrenals. We demonstrate that VSNL1 overexpression in adrenocortical carcinoma cells (NCI H295R) upregulates basal and angiotensin II (Ang II)-stimulated CYP11B2 gene expression 3.2- and 1.5-fold, respectively. Conversely, silencing VSNL1 by RNA interference decreases Ang II-stimulated CYP11B2 expression and aldosterone secretion by 41 and 34.5%, respectively. Mutations in the potassium channel KCNJ5 have been identified in APA that result in sodium influx, membrane depolarization and are postulated to result in calcium influx in adrenal glomerulosa cells. VSNL1 and CYP11B2 are 8.1- and 6.0-fold more highly expressed, respectively, in APA harbouring KCNJ5 mutations compared to those without, and the upregulation of VSNL1 in these APA accounts for the overexpression of VSNL1 in the total APA sample set compared to normal adrenals. Silencing VSNL1 in H295R cells renders them sensitive to ionomycin-induced apoptosis indicating that VSNL1 protects these cells against calcium-induced cell death. Concomitant expression of mutated KCNJ5 (G151R) and silencing VSNL1 results in apoptosis of H295R cells, an effect that is blocked by nifedipine and is absent using a control siRNA or when wild-type KCNJ5 is expressed and VSNL1 is silenced. These data demonstrate that VSNL1 plays a dual function in vitro in the regulation of CYP11B2 gene expression and in the inhibition of calcium-induced apoptosis. Additionally, VSNL1 may play a role in the pathophysiology of APA harbouring mutations in the potassium channel KCNJ5 via its anti-apoptotic function in response to calcium cytotoxicity and its effect on aldosterone production.
Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.
Funding: This work was supported, however funding details are unavailable.