Prorenin

Prorenin is an inactive precursor of renin that is secreted by the juxtaglomerular cells of the kidney. It is converted to renin in the body, which plays a crucial role in the RAS.

Function

Prorenin is a glycoprotein that is synthesized and stored in the juxtaglomerular cells of the kidney. It is secreted into the bloodstream where it circulates in an inactive form. When the body needs to increase blood pressure or blood volume, prorenin is converted into renin by the removal of a 43-amino acid prosegment.

Role in Renin-Angiotensin System

The RAS is a hormone system that regulates blood pressure and fluid balance. When blood volume or sodium levels in the body are low, or blood potassium is high, cells in the kidney release prorenin. It is then converted to renin, which acts on a protein called angiotensinogen, converting it into angiotensin I. This is then converted into angiotensin II by an enzyme called ACE. Angiotensin II is a potent vasoconstrictor, which means it narrows the blood vessels and increases blood pressure.

Clinical Significance

Elevated prorenin levels can be an indicator of certain medical conditions. For example, in diabetes, prorenin levels can be significantly increased. This is thought to contribute to the development of diabetic nephropathy, a kidney disease that can occur in people with diabetes.

In addition, mutations in the gene that encodes for prorenin can lead to a rare disorder called renin-secreting tumor, or reninoma. This tumor leads to overproduction of renin and prorenin, causing high blood pressure and low potassium levels.

See Also

• Renin
• Renin-Angiotensin System
• Diabetes mellitus
• Reninoma

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