Figure 4.

Schematic representation of myostatin signaling and mechanisms of its repression. Myostatin is a soluble myokine that acts as a negative regulator of muscle growth and mass by binding to activin type II receptors (ActRII A/B) on the cell. This binding activates a signaling cascade involving several different kinases such as Mitogen-activated protein kinase (MAPK), Sma- and Mad-Against Decapentaplegic (SMAD)-related proteins and protein kinase B (AKT). The activated proteins then translocate to the nucleus where they affect target gene expression, resulting in negative changes in muscle and bone tissues. Blocking myostatin binding to the receptor through different pharmaceutical approaches results in increased muscle and possibly also bone quality.