Bigger Muscles, Stronger Muscles? The Strange Case of Myostatin
André K. Yamada
Myostatin is a peculiar prototype that functions as a negative regulator of muscle mass.
Myostatin limits muscle growth by binding to activin type II receptors (ActvRIIB) and type I receptors (ALK4 and ALK5).
Although inhibition of myostatin results in exacerbated muscle growth, it is not entirely clear how this is translated to the production of muscle force.
Among the regulatory genes, only oestrogen-related receptor γ was found to be up-regulated in response to exercise. It is known that over-expression of this gene promotes mitochondrial enlargement, angiogenesis and slow Myosin Heavy Chain expression.
A more comprehensive approach would be to study humans, but inhibition of myostatin would not be ethical, and genetic manipulation, drugs and biopsy samples would be necessary.