mineralocorticoid biosynthetic process

Definition

Target type: biologicalprocess

The chemical reactions and pathways resulting in the formation of mineralocorticoids, hormonal C21 corticosteroids synthesized from cholesterol. [ISBN:0198506732]

The mineralocorticoid biosynthetic process is a complex pathway that culminates in the production of aldosterone, a steroid hormone essential for maintaining electrolyte balance and blood pressure. The process begins in the adrenal cortex, specifically in the zona glomerulosa. Here, cholesterol, the precursor molecule, undergoes a series of enzymatic modifications to ultimately yield aldosterone.

The initial steps involve the conversion of cholesterol to pregnenolone through the action of the enzyme cholesterol side-chain cleavage enzyme (CYP11A1). Pregnenolone is then transformed into progesterone by 3 beta-hydroxysteroid dehydrogenase (3beta-HSD). Progesterone is the starting point for the synthesis of both glucocorticoids and mineralocorticoids.

The next step in the mineralocorticoid pathway involves the conversion of progesterone to deoxycorticosterone (DOC) by the enzyme 21-hydroxylase (CYP21A2). DOC is then hydroxylated at the 11-beta position by 11-beta-hydroxylase (CYP11B1) to yield corticosterone.

The crucial step in mineralocorticoid synthesis is the conversion of corticosterone to aldosterone, catalyzed by the enzyme aldosterone synthase (CYP11B2). This enzyme is highly specific for the zona glomerulosa of the adrenal cortex and is responsible for the final steps of aldosterone biosynthesis.

Aldosterone synthase catalyzes two key reactions. First, it hydroxylates corticosterone at the 18 position to produce 18-hydroxycorticosterone. This is followed by a second hydroxylation at the 11 position, resulting in the formation of aldosterone.

The biosynthesis of aldosterone is tightly regulated by a number of factors, including the renin-angiotensin-aldosterone system (RAAS). When blood pressure or blood volume drops, the RAAS is activated, leading to the release of renin from the kidneys. Renin converts angiotensinogen to angiotensin I, which is further cleaved to angiotensin II by angiotensin-converting enzyme (ACE). Angiotensin II acts on the adrenal cortex to stimulate aldosterone production.

Aldosterone, upon release into the bloodstream, exerts its effects on the kidneys, where it promotes sodium reabsorption and potassium excretion. This ultimately leads to increased blood volume and blood pressure, restoring the balance of electrolytes and maintaining normal cardiovascular function.'
"

Proteins (4)

Compounds (19)