IGF-1 induces human myotube hypertrophy by increasing cell recruitment

• Published in: Experimental cell research Vol. 299; no. 1; pp. 148 - 158
• Main Authors: Jacquemin, V, Furling, D, Bigot, A, Butler-Browne, G.S, Mouly, V
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 10.09.2004; Elsevier
• Subjects: Adolescent; Aged; Cell Division - drug effects; Cell Division - physiology; Cell Nucleus - drug effects; Cell Nucleus - metabolism; Cell Nucleus - ultrastructure; Cells, Cultured; Cellular Senescence - drug effects; Cellular Senescence - physiology; Humans; Hypertrophy; Hypertrophy - chemically induced; Hypertrophy - metabolism; IGF-1; Infant, Newborn; Insulin-Like Growth Factor I - metabolism; Insulin-Like Growth Factor I - pharmacology; Life Sciences; Membrane Fusion - drug effects; Membrane Fusion - physiology; Muscle Fibers, Skeletal - cytology; Muscle Fibers, Skeletal - drug effects; Muscle Fibers, Skeletal - metabolism; Muscle, Skeletal - cytology; Muscle, Skeletal - growth & development; Muscle, Skeletal - metabolism; Myosin Heavy Chains - drug effects; Myosin Heavy Chains - metabolism; Proliferation; Satellite cell; Satellite Cells, Skeletal Muscle - drug effects; Skeletal muscle; Up-Regulation - drug effects; Up-Regulation - physiology; MPD; FDA; MyHC; IGFBPs; DM; IGF-1; Proliferation; Skeletal muscle; FBS; PI; Satellite cell; BrdU; Hypertrophy
• ISSN: 0014-4827; 1090-2422
• DOI: 10.1016/j.yexcr.2004.05.023

Insulin-like growth factor-1 (IGF-1) has been shown in rodents (i) in vivo to induce muscle fiber hypertrophy and to prevent muscle mass decline with age and (ii) in vitro to enhance the proliferative life span of myoblasts and to induce myotube hypertrophy. In this study, performed on human primary cultures, we have shown that IGF-1 has very little effect on the proliferative life span of human myoblasts but does delay replicative senescence. IGF-1 also induces hypertrophy of human myotubes in vitro, as characterized by an increase in the mean number of nuclei per myotube, an increase in the fusion index, and an increase in myosin heavy chain (MyHC) content. In addition, muscle hypertrophy can be triggered in the absence of proliferation by recruiting more mononucleated cells. We propose that IGF-1-induced hypertrophy can involve the recruitment of reserve cells in human skeletal muscle.