Angiotensinogen

Angiotensinogen is a protein that is produced by the liver and is a precursor to angiotensin, a peptide hormone that plays a crucial role in the renin-angiotensin system (RAS). This system is essential for the regulation of blood pressure and fluid balance in the body.

Structure

Angiotensinogen is a glycoprotein consisting of 452 amino acids. It is encoded by the AGT gene located on chromosome 1 in humans. The protein undergoes several post-translational modifications, including glycosylation, which are important for its function.

Function

The primary function of angiotensinogen is to serve as the substrate for the enzyme renin. When blood pressure is low, the kidneys release renin, which cleaves angiotensinogen to produce angiotensin I. Angiotensin I is then converted to angiotensin II by the action of angiotensin-converting enzyme (ACE) primarily in the lungs.

Angiotensin II is a potent vasoconstrictor that increases blood pressure by causing blood vessels to constrict. It also stimulates the release of aldosterone from the adrenal glands, which promotes sodium and water retention by the kidneys, further increasing blood pressure.

Clinical Significance

Mutations in the AGT gene can lead to various hypertension disorders. Elevated levels of angiotensinogen are associated with an increased risk of cardiovascular disease. Angiotensinogen levels can be influenced by factors such as inflammation, hormones, and diet.

Regulation

The expression of angiotensinogen is regulated by several factors, including cytokines, hormones like estrogen and glucocorticoids, and nutritional status. Inflammatory cytokines such as interleukin-6 (IL-6) can increase the production of angiotensinogen, linking inflammation to hypertension.

See Also

• Renin-angiotensin system
• Angiotensin
• Renin
• Angiotensin-converting enzyme
• Hypertension
• Aldosterone