Apelin

Apelin is a peptide that is encoded by the APLN gene in humans. It is widely expressed in various tissues, including the heart, lung, kidney, liver, adipose tissue, and central nervous system. Apelin is known to have several important physiological roles, such as regulating blood pressure, cardiac contractility, and fluid balance. It is also involved in the pathophysiology of several diseases, including cardiovascular disease, diabetes, and obesity.

Structure and Function

Apelin is a 77-amino acid prepropeptide that is cleaved to produce active peptides of varying lengths. The most common forms are apelin-36, apelin-17, apelin-13, and [Pyr1]apelin-13. These peptides bind to the apelin receptor, also known as APJ, which is a G protein-coupled receptor.

The binding of apelin to its receptor triggers a cascade of intracellular events that lead to various physiological responses. For example, in the cardiovascular system, apelin promotes vasodilation, reduces cardiac preload and afterload, and enhances cardiac contractility. In the kidney, it promotes diuresis and natriuresis. In the central nervous system, apelin regulates energy metabolism and food intake.

Clinical Significance

Apelin has been implicated in several diseases. In cardiovascular disease, decreased levels of apelin have been associated with heart failure, hypertension, and atherosclerosis. In diabetes, apelin improves insulin sensitivity and glucose uptake in skeletal muscle. In obesity, apelin regulates adipocyte differentiation and lipid metabolism.

There is also evidence that apelin may have therapeutic potential. For example, apelin analogs have been shown to improve cardiac function in animal models of heart failure. In addition, apelin has been proposed as a potential biomarker for various diseases, including heart failure and diabetes.

See Also

• Peptide
• G protein-coupled receptor
• Cardiovascular disease
• Diabetes
• Obesity