Follistatin (FST-344)

Follistatin is a glycoprotein that is endogenously produced across numerous tissues in higher animals. It is a secreted protein that plays a significant role as a regulator of muscle mass and has other functions within the endocrine system.

The primary mechanism of action for Follistatin is its function as a potent antagonist of Myostatin (also known as GDF-8). Myostatin is a protein that acts as a negative regulator of muscle growth, effectively putting a limit on muscle development. Follistatin binds directly to Myostatin and inhibits its activity, which can lead to an increase in muscle fiber size (hypertrophy) and number (hyperplasia).

In addition to neutralizing Myostatin, Follistatin also binds to and inhibits other members of the Transforming Growth Factor-beta (TGF-β) superfamily, most notably Activin. This interaction is crucial for regulating various physiological processes, including hormonal feedback in the reproductive system. Due to its muscle-building capabilities, Follistatin is under investigation as a potential therapeutic agent for conditions characterized by muscle wasting, such as sarcopenia, cachexia, and some forms of muscular dystrophy.