Biological Functions
Human plasma contains a glycoprotein called angiotensinogen,
which serves as the only known substrate
for renin. Angiotensinogen must undergo proteolysis
before active portions of the protein are sufficiently unmasked
to exert biological effects. Angiotensinogen is
synthesized in many organs, including the liver, brain,
kidney, and fat. Its gene transcription and plasma concentrations
increase following treatment with adrenocorticotropic
hormone (ACTH), glucocorticoids, thyroid
hormone, and estrogens, as well as during
pregnancy and inflammation and after nephrectomy.
Angiotensinogen also has been found in large quantities
in cerebrospinal and amniotic fluid. Mutations in
the angiotensinogen gene have been reported to be
linked to human hypertension.
Biological Activity
Angiotensinogen acts as a precursor molecule in the renin-angiotensin-aldosterone system (RAAS) pathway. It is a part of the renin-angiotensin system th at regulates blood pressure and fluid balance. Moreover, overactivation of the RAAS system has been associated with the development of several types of cancer, cardiovascular and renal diseases. Furthermore, in certain cancers angiotensin II has been shown to promote cancer metastasis.
