ABSTRACT
Background: Familial hyperaldosteronism type I is caused by the generation of a chimeric aldosterone synthase enzyme (ASCE) which is regulated by ACTH instead of angiotensin II. We have reported that in vitro, the wild-type (ASWT) and chimeric aldosterone synthase (ASCE) enzymes are inhibited by progesterone and estradiol does not affect their activity. Aim: To explore the direct action of testosterone on ASWT and ASCE enzymes. Material and Methods: HEK-293 cells were transiently transfected with vectors containing the full ASWT or ASCE cDNAs. The effect of testosterone on AS enzyme activities was evaluated incubating HEK-cells transfected with enzyme vectors and adding deoxycorticosterone (DOC) alone or DOC plus increasing doses of testosterone. Aldosterone production was measured by HPLC-MS/MS. Docking of testosterone within the active sites of both enzymes was performed by modelling in silico. Results: In this system, testosterone inhibited ASWT (90% inhibition at five pM, 50% inhibitory concentration (IC50) =1.690 pM) with higher efficacy andpotency than ASCE (80% inhibition at five pM, IC50=3.176 pM). Molecular modelling studies showed different orientation of testosterone in ASWT and ASCE crystal structures. Conclusions: The inhibitory effect of testosterone on ASWT or ASCE enzymes is a novel non-genomic testosterone action, suggesting that further clinical studies are needed to assess the role of testosterone in the screening and diagnosis of primary aldosteronism.
ABSTRACT
About 15% of the essential hypertensive patients would have a low activity of the 11ßHSD2 enzyme, which inactivates cortisol (F) to cortisone (E). Gene expression can be negatively regulated by miRNA. Urinary exosomes and their specific content (miRNA/proteins) represent a valuable tool as a biomarker for the diagnosis and prognosis of the disease. Aim: To evaluate the expression of miRNA specific for 11ßHSD2 in samples of urinary exosomes and to determine its association with biochemical variables associated with mineralocorticoid metabolism. Subjects and Methods: Cross-sectional study in subjects between 10-60 years. They were classified into subjects with high F/E (> p75) and low cortisone (< p25) and control subjects. The urinary exosomes were isolated with the Invitrogen kit. Bioinformatic analysis was performed with Mir Walk to identify specific miRNAs of HSD11B2. The expression of miRNA was evaluated by qRT PCR. The comparisons were made with the Mann-Whitney test. Results: 7.1% of the subjects are suggestive of a partial deficiency of 11ßHSD2 (NC-AME). The expression of miR-488 was higher in NC-AME than in controls (5839 ± 1719 vs 3,437 ± 2,581; p = 0.01). We found positive associations between mir-615 and ARP; miR-488 and the sodium/potassium ratio; miR-1205 with age and urinary sodium excretion; miR-494 with age, activity MMP9 and NGAL. Conclusion: We identified high expression of miR488 in NC-AME subjects and associations of miRNAs with biochemical variables associated with mineralocorticoid metabolism. Thus, exosomes and their miRNA content could be potential regulators and biomarkers of 11ßHSD2 activity.