ABSTRACT
Myostatin (GDF-8) was fi rst identifi ed as a new member of the transformingbeta growth factor (TGF-beta) superfamily of growth and differentiation factors that was highly expressed in skeletal muscle progenitors (McPherron et al. 1997). The functional characterization of myostatin using a myostatin-knockout mouse led to the surprising observation that loss of normal myostatin signaling produced a dramatic increase in muscle mass (McPherron et al. 1997). Since the original discovery of myostatin, its role in muscle development and muscle regeneration has been explored using a variety of in vivo and in vitro approaches (Zimmers et al. 2002; ReisPorszaz et al. 2003; Li et al. 2008; McFarlane et al. 2011). These studies have generally shown that myostatin plays an important role in the proliferation and differentiation of myoblasts, and that inhibiting myostatin expression improves muscle regeneration and increases muscle fi ber size and number (Lee 2004; Burks and Cohn 2011).
