Monitor of the myostatin autocrine action during differentiation of embryonic chicken myoblasts into myotubes: effect of IGF-I.
Myogenesis is regulated through the proliferation and differentiation of myoblasts expressing myostatin which functions as a negative regulator by generating Smad signals. Here, we monitored the autocrine action of myostatin in quiescent chicken myoblasts transfected with the Smad-mediated promoter reporter vector to evaluate the modulation of several growth factors. During differentiation of myoblasts into myotubes, stretched and spherical types of myoblasts were observed at 12 h after induction, at which the promoter activity began to increase. Maximal promoter activity was observed at approximately 30 h. Multinucleated myotubes were markedly formed at 72 h, but the activity was very low. IGF-I, known as a positive regulator of myogenesis, increased the promoter activity, but the increase was rather small at its high concentration (100 ng/ml). IGF-I significantly increased the level of myostatin transcript in myoblasts and newly formed myotubes at 24 h, but not at 36 h. However, the cell fusion of myoblasts was not accelerated in the presence of IGF-I. Consequently, this study indicates that the autocrine action of myostatin is partially enhanced by IGF-I through increasing its expression.
Kurokawa
Masatoshi
M
Laboratory of Reproductive Physiology and Biotechnology, Department of Animal and Marine Bioresource Sciences, Graduate School of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan.
Sato
Fuminori
F
Aramaki
Shinya
S
Soh
Tomoki
T
Yamauchi
Nobuhiko
N
Hattori
Masa-aki
MA
D000818:Animals; D019898:Autocrine Communication / Q000187:drug effects*; D002454:Cell Differentiation / Q000187:drug effects*; D048430:Cell Shape / Q000187:drug effects; D002478:Cells, Cultured; D002642:Chick Embryo; D004247:DNA / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D008156:Luciferases / Q000378:metabolism; D018485:Muscle Fibers, Skeletal / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D032446:Myoblasts / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D055435:Myostatin / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
D055435:Myostatin; D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I; D004247:DNA; D008156:Luciferases