Domestic Animal Endocrinology 35 (2008) 263–273 Available online at www.sciencedirect.com Extracellular matrix proteoglycan decorin-mediated myogenic satellite cell responsiveness to transforming growth factor-1 during cell proliferation and differentiation Decorin and transforming growth factor-1 in satellite cells Xuehui Li a , Douglas C. McFarland b , Sandra G. Velleman a,∗ a Department of Animal Sciences, Ohio Agricultural Research and Development Center, The Ohio State University, 1680 Madison Avenue, Wooster, OH 44691, USA b Department of Animal and Range Sciences, South Dakota State University, Brookings, SD 57007, USA Received 25 April 2008; received in revised form 6 June 2008; accepted 7 June 2008 Abstract Transforming growth factor-1 (TGF-1) is a potent inhibitor of muscle cell proliferation and differentiation. Decorin, a small proteoglycan in the extracellular matrix, binds to TGF-1 and modulates the activity of TGF-1 during muscle cell growth and development. However, its interaction with TGF-1 and involvement in myogenesis is not well characterized. In the present study, chicken myogenic satellite cells, myogenic precursors for muscle growth and repair, were isolated from the pectoralis major muscle and used to investigate the biological function of TGF-1 and decorin during myogenesis. The over-expression of decorin in satellite cells significantly increased cell proliferation, compared to the control cells. Consistent with this result, reducing decorin expression decreased cell proliferation, which suggests a decorin-mediated mechanism is involved in the regulation of myogenic satellite cell proliferation. Satellite cells over-expressing decorin were less sensitive to TGF-1 during proliferation, which indicates that decorin may sequester TGF-1 leading to increased proliferation. During satellite cell differentiation, the over-expression of decorin induced differentiation by increasing the muscle specific creatine kinase concentration. However, the addition of TGF-1 diminished decorin-mediated cell responsiveness to TGF-1 during differentiation. Taken together, these results suggest that decorin induces myogenic satellite cell proliferation and differentiation by regulating cellular responsiveness to TGF-1. An alternative TGF-1-independent pathway may be involved in the regulation of satellite cells by decorin. © 2008 Elsevier Inc. All rights reserved. Keywords: Decorin; Extracellular matrix; Myogenesis; Satellite cells; Transforming growth factor-1 1. Introduction During skeletal muscle development, myoblasts pro- liferate, align with each other, and fuse to form multinucleated myotubes which differentiate into mus- ∗ Corresponding author. Tel.: +1 330 263 3905; fax: +1 330 263 3949. E-mail address: velleman.1@osu.edu (S.G. Velleman). cle fibers. Growth factors and the extracellular matrix (ECM) environment surrounding the cells are involved in regulating muscle cell proliferation and differentiation. The ECM is defined as a dynamic network of polysac- charides and proteins that are immobilized outside cells [1]. Communication between the ECM and cells plays a pivotal role in the regulation of cellular events. The ECM is involved in the regulation of gene expression, cell proliferation, migration, adhesion, and differentia- tion, which are all essential for muscle development and 0739-7240/$ – see front matter © 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.domaniend.2008.06.002