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Aldosterone synthase, also called steroid 18-hydroxylase, corticosterone 18-monooxygenase or P450C18, is a steroid hydroxylase cytochrome P450 enzyme involved in the biosynthesis of the mineralocorticoid aldosterone and other steroids. The enzyme catalyzes sequential hydroxylations of the steroid angular methyl group at C18 after initial 11β ...
The inactivating mutation leads to elevated local concentrations of cortisol in the aldosterone sensitive tissues like the kidney. Cortisol at high concentrations can cross-react and activate the mineralocorticoid receptor due to the non-selectivity of the receptor, leading to aldosterone-like effects in the kidney.
Aldosterone has effects on most or all cells of the body but, clinically, the most important actions are in the kidney, on cells of the late distal convoluted tubule and medullary collecting duct. In the principal cells aldosterone increases activity of basolateral membrane sodium-potassium ATPase and apical epithelial sodium channels, ENaC ...
In these people the defect had the effect of an isolated impairment of sex steroid (e.g., DHEA in the adrenal, but also gonadal testosterone and estrogens) synthesis, whereas mineralocorticoid (e.g., aldosterone) and glucocorticoid (e.g., cortisol) levels remain normal. [citation needed]
This layer is the main site for production of aldosterone, a mineralocorticoid, by the action of the enzyme aldosterone synthase. [ 16 ] [ 17 ] Aldosterone plays an important role in the long-term regulation of blood pressure .
These enzymes are nearly identical (they share 11β-hydroxylation and 18-hydroxylation functions), but aldosterone synthase is also able to perform an 18-oxidation. Moreover, aldosterone synthase is found within the zona glomerulosa at the outer edge of the adrenal cortex; 11β-hydroxylase is found in the zona glomerulosa and zona fasciculata.
A mineralocorticoid receptor antagonist (MRA or MCRA) [1] or aldosterone antagonist, is a diuretic drug which antagonizes the action of aldosterone at mineralocorticoid receptors. This group of drugs is often used as adjunctive therapy, in combination with other drugs, for the management of chronic heart failure .
In aldosterone-producing adrenocortical adenoma (APA), which is the main cause of primary aldosteronism, the enzyme aldosterone synthase (CYP11B2) plays a crucial role in aldosterone production. Somatic mutations in genes like KCNJ5 and CACNA1D can lead to an overexpression of CYP11B2 and increased production of aldosterone. CYP11B2 catalyzes ...