Enhancement of C2C12 myoblast proliferation and differentiation by GASP-2, a myostatin inhibitor.

Background: GASP-2 is a secreted multi-domain glycoprotein known as a specific inhibitor of myostatin and GDF-11. Here we investigate the role of GASP-2 on myogenesis and the effect of its glycosylation on its activity.

Methods: GASP-2 overexpression or knockdown by shRNAs were carried out on C2C12 myoblasts cells. analysis of GASP-2 protein was performed to identify its glycosylation sites. We produced a mouse recombinant GASP-2 protein in a prokaryotic system to obtain a fully deglycosylated protein allowing us to study the importance of this post-translational modification on GASP-2 activity.

Results: Both mature and deglycosylated GASP-2 proteins increase C2C12 proliferation and differentiation by inhibiting the myostatin pathway. and western-blot analyses revealed that GASP-2 presents one consensus sequence for -glycosylation and six potential sites of mucin-type -glycosylation.

Conclusions: GASP-2 promotes myogenesis and thus independently of its glycosylation.

General Significance: This is the first report demonstrating that GASP-2 promotes proliferation and differentiation of myoblasts by inhibiting the canonical pathway of myostatin.