Transfection of L6 myoblasts with adipocyte fatty acid-binding protein cDNA does not affect fatty acid uptake but disturbs lipid metabolism and fusion.
We studied the involvement of fatty acid-binding protein (FABP) in growth, differentiation and fatty acid metabolism of muscle cells by lipofection of rat L6 myoblasts with rat heart (H) FABP cDNA or with rat adipocyte (A) FABP cDNA in a eukaryotic expression vector which contained a puromycin acetyltransferase cassette. Stable transfectants showed integration into the genome for all constructs and type-specific overexpression at the mRNA and protein level for the clones with H-FABP and A-FABP cDNA constructs. The rate of proliferation of myoblasts transfected with rat A-FABP cDNA was 2-fold higher compared with all other transfected cells. In addition, these myoblasts showed disturbed fusion and differentiation, as assessed by morphological examination and creatine kinase activity. Uptake rates of palmitate were equal for all clone types, in spite of different FABP content and composition. Palmitate oxidation over a 3 h period was similar in all clones from growth medium. After being cultured in differentiation medium, mock- and H-FABP-cDNA-transfected cells showed a lower fatty acid-oxidation rate, in contrast with A-FABP-cDNA-transfected clones. The ratio of [14C]palmitic acid incorporation into phosphatidylcholine and phosphatidylethanolamine of A-FABP-cDNA-transfected clones changed in the opposite direction in differentiation medium from that of mock- and H-FABP-cDNA-transfected clones. In conclusion, transfection of L6 myoblasts with A-FABP cDNA does not affect H-FABP content and fatty acid uptake, but changes fatty acid metabolism. The latter changes may be related to the observed fusion defect.
Prinsen
C F
CF
Department of Biochemistry, University of Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands.
Veerkamp
J H
JH
D017667:Adipocytes / Q000378:metabolism*; D000818:Animals; D015152:Blotting, Northern; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002455:Cell Division; D002459:Cell Fusion / Q000235:genetics; D002460:Cell Line; D003001:Cloning, Molecular; D018076:DNA, Complementary; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D018996:Myelin P2 Protein / Q000235:genetics / Q000378:metabolism*; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D019308:Palmitic Acid / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism*; D051381:Rats; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D014162:Transfection
D002352:Carrier Proteins; D018076:DNA, Complementary; C490174:Fabp7 protein, rat; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D018996:Myelin P2 Protein; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D010743:Phospholipids; D011994:Recombinant Proteins; D019308:Palmitic Acid