Cellular and molecular regulation of muscle growth and development in meat animals.
Although in vivo and in vitro studies have established that anabolic steroids, transforming growth factor-beta (TGF-beta), and myostatin affect muscle growth in meat-producing animals, their mechanisms of action are not completely understood. Anabolic steroids have been widely used as growth promoters in feedlot cattle for over 50 yr. A growing body of evidence suggests that increased muscle levels of IGF-I and increased muscle satellite cell numbers play a role in anabolic steroid enhanced muscle growth. In contrast to anabolic steroids, the members of the TGF-beta-myostatin family suppress muscle growth in vivo and suppress both proliferation and differentiation of cultured myogenic cells. Recent evidence suggests that IGFBP-3 and IGFBP-5 play a role in mediating the proliferation-suppressing actions of both TGF-beta and myostatin on cultured myogenic cells. Consequently, this review will focus on the roles of IGF-I and IGFBP in the cellular and molecular mechanisms of action of anabolic steroids and TGF-beta and myostatin, respectively.
Dayton
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Department of Animal Science, University of Minnesota, St. Paul, MN 55108, USA. wdayton@umn.edu
White
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D000818:Animals; D002417:Cattle; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D018969:Insulin-Like Growth Factor Binding Proteins / Q000032:analysis / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000032:analysis / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000166:cytology / Q000254:growth & development*; D055435:Myostatin; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
D018969:Insulin-Like Growth Factor Binding Proteins; D055435:Myostatin; D016212:Transforming Growth Factor beta; D007334:Insulin-Like Growth Factor I