Matrix gla protein: An extracellular matrix protein regulates myostatin expression in the muscle developmental program

- MGP regulates the expression of myogenic regulatory factors
- MGP helps in the modeling of extracellular matrix
- MGP positively regulates the expression of myostatin
- MGP prevents interaction between myostatin and activin receptor type IIB, and thereby controls TGF-β signaling events

AimSkeletal muscle development involves interactions between intracellular and extracellular factors that act in concert to regulate the myogenic process. Matrix gla protein (MGP), a well-known inhibitor of calcification in soft tissues, has been reported to be highly up-regulated during myogenesis. Our interest in the regulation of muscle satellite cells (MSCs) by extracellular matrix (ECM) led us to investigate the effects of MGP during the progression of myogenesis.MethodologyParticipation of MGP in the myogenic process was investigated in vitro using C2C12 cells, and knockdown of its gene was performed to determine its effects on the expression of myogenic regulatory factors (MRFs) and other ECM genes. In addition, interactions between MGP, Fibromodulin (FMOD), and Myostatin (MSTN) were investigated by conducting co-immunoprecipitation and in silico studies.Key findingsMatrix gla protein knockdown (MGPkd) shows pronounced effects during myogenesis as evidenced by the down regulation of myogenic marker (MYOG and MYOD), and ECM (COL1α1 and FMOD) genes. Down-regulation of MSTN expression in MGPkd cells suggests its role in coordinating the regulation of MSTN expression. Having strong affinity for ACVRIIB receptor, in silico data confirms MGP interference in the interaction of MSTN with ACVRIIB. These findings show MGP inhibits MSTN functionally by disrupting its binding to receptor.SignificanceThe present study provides insights of an ECM protein that participates in the regulation of the myogenic program by inhibiting the activity of the myogenic negative regulator MSTN, which suggests that MGP might be used for designing novel inhibitors that can promote muscle regeneration or treat muscle atrophy.