Involvement of the GLUT 3 transporter in myogenic regulation.
We have recently demonstrated a close relationship between the GLUT 3 transporter and the myogenic ability of rat skeletal L6 myoblasts [1]. This investigation examined the effects of over- and under-expression of the GLUT 3 transporter on both biochemical and morphological differentiation. L6 transfectants expressing two to five times the normal L6 GLUT 3 transcript level were impaired in the expression of myogenesis-associated genes, such as myogenin, MLC, MHC and TnT, and in myotube formation. Similar defects were also observed in myoblast mutants expressing less than 20% of the normal GLUT 3 level. Forced expression of an exogenous GLUT 3 cDNA could partially rescue the myogenic defect of these GLUT 3 mutants. However, such myogenic defects were not observed in L6 GLUT 3 antisense transfectants expressing 39% of the normal L6 GLUT 3 level. These data suggest that myogenic differentiation will proceed only within a critical level of the GLUT 3 transporter. The optimal GLUT 3 content for myogenesis ranges from around 2 x 10(5) to 5 x 10(5) molecules per cell in day 2 cultures; GLUT 3 levels outside this range have a negative effect on myogenesis. Our data suggest that GLUT 3 may regulate myogenesis by modulating the levels of signal transducers required for expression of myogenin and muscle-specific contractile protein genes.
Broydell
M
M
Department of Biochemistry, University of Western Ontario, London, Ontario, Canada.
Mazzuca
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Abidi
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Kudo
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Lo
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D000818:Animals; D002454:Cell Differentiation / Q000235:genetics; D002460:Cell Line; D016373:DNA, Antisense / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D005786:Gene Expression Regulation; D051274:Glucose Transporter Type 3; D006801:Humans; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000502:physiology*; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D016296:Mutagenesis; D018006:Myogenic Regulatory Factors / Q000096:biosynthesis / Q000502:physiology*; D009419:Nerve Tissue Proteins; D051381:Rats; D014158:Transcription, Genetic; D014162:Transfection
D016373:DNA, Antisense; D018076:DNA, Complementary; D051274:Glucose Transporter Type 3; D009004:Monosaccharide Transport Proteins; D018006:Myogenic Regulatory Factors; D009419:Nerve Tissue Proteins; C495687:SLC2A3 protein, human; C495690:Slc2a3 protein, rat