[Show abstract][Hide abstract] ABSTRACT: Satellite cells exist in postnatal muscle tissue and constitute the main source of muscle precursor cells for growth and repair. These cells carry out important roles for skeletal muscle formation postnatally during growth of muscle mass as well as damage-induced regenerative processes. Muscle regeneration supports muscle function in aging and has a role in the functional impairment caused by progressive neuromuscular diseases. Major substances controlling this process are growth factors and extracellular matrix. Myostatin, a member of TGF-beta family, was mainly expressed in muscle tissue. Decorin, a member of the small leucine-rich proteoglycan gene family, is composed of a core protein and a dermatan/chondroitin sulfate chain. Recent studies have shown that decorin enhanced the proliferation and differentiation of myogenic cells by suppressing myostatin activity. Thus, decorin appears to be a new molecule in the myostatin signaling pathway and a promising target for treatment of progressive neuromuscular diseases. Therefore, in this study, we examined the localization of decorin as well as myostatin in a muscular dystrophy model in mdx mice and B10 Scott Snells mice as a control to elucidate the differences between decorin and myostatin messages as well as protein distribution. This study revealed increased expression of decorin protein as well as mRNA at the regenerative stage of mdx mice compared to early stages, while only weak expression of decorin was detected in the control mice. Our study contributes to identifying the relationship between decorin and myostatin as well as the development of a therapeutic strategy for progressive neuromuscular diseases.
[Show abstract][Hide abstract] ABSTRACT: Mammals exhibit marked morphological differences in the muscles surrounding the jaw bone due to differences in eating habits. Furthermore, the myofiber properties of the muscles differ with function. Since the muscles in the oral region have various functions such as eating, swallowing, and speech, it is believed that the functional role of each muscle differs. Therefore, to clarify the functional role of each masticatory muscle, the myofiber properties of the adult mouse masticatory muscles were investigated at the transcriptional level. Expression of MyHC-2b with a fast contraction rate and strong force was frequently noted in the temporal and masseter muscles. This suggests that the temporal and masseter muscles are closely involved in rapid antero-posterior masticatory movement, which is characteristic in mice. Furthermore, expression of MyHC-1 with a low contraction rate and weak continuous force was frequently detected in the lateral pterygoid muscle. This suggests that, in contrast to other masticatory muscles, mouse lateral pterygoid muscle is not involved in fast masticatory movement, but is involved in functions requiring continuous force such as retention of jaw position. This study revealed that muscles with different roles function comprehensively during complicated masticatory movement.
The Bulletin of Tokyo Dental College 06/2008; 49(2):53-8.