| First Author | Dahiya S | Year | 2011 |
| Journal | Hum Mol Genet | Volume | 20 |
| Issue | 22 | Pages | 4345-59 |
| PubMed ID | 21846793 | Mgi Jnum | J:176891 |
| Mgi Id | MGI:5293160 | Doi | 10.1093/hmg/ddr362 |
| Citation | Dahiya S, et al. (2011) Elevated levels of active matrix metalloproteinase-9 cause hypertrophy in skeletal muscle of normal and dystrophin-deficient mdx mice. Hum Mol Genet 20(22):4345-59 |
| abstractText | Matrix metalloproteinases (MMPs) are a group of extracellular proteases involved in tissue remodeling in several physiological and pathophysiological conditions. While increased expression of MMPs (especially MMP-9) has been observed in skeletal muscle in numerous conditions, their physiological significance remains less-well understood. By generating novel skeletal muscle-specific transgenic (Tg) mice expressing constitutively active mutant of MMP-9 (i.e. MMP-9G100L), in this study, we have investigated the effects of elevated levels of MMP-9 on skeletal muscle structure and function in vivo. Tg expression of enzymatically active MMP-9 protein significantly increased skeletal muscle fiber cross-section area, levels of contractile proteins and force production in isometric contractions. MMP-9 stimulated the activation of the Akt signaling pathway in Tg mice. Moreover, expression of active MMP-9 increased the proportion of fast-type fiber in soleus muscle of mice. Overexpression of MMP-9 also considerably reduced the deposition of collagens I and IV in skeletal muscle in vivo. In one-year-old mdx mice (a model for Duchenne muscular dystrophy, DMD), deletion of the Mmp9 gene reduced fiber hypertrophy and phosphorylation of Akt and p38 mitogen-activated protein kinase. Collectively, our study suggests that elevated levels of active MMP-9 protein cause hypertrophy in skeletal muscle and that the modulation of MMP-9 levels may have therapeutic value in various muscular disorders including DMD. |
