Glycoprotein glycans may not be necessary for the differentiation of skeletal myoblasts.
Previous work using glycosylation inhibitors has suggested that high-mannose type but not complex type oligosaccharides on the surface of cells may play a role in the differentiation of skeletal myoblasts. Earlier, we had shown that a concanavalin A-resistant mutant derived from an L6 myoblast line fails to differentiate in a medium containing 10% horse serum. Here we show that one such concanavalin A-resistant mutant (D-1) which was reported to have oligosaccharides of the type Man(3-5)G1cNAc2, shows significant fusion ability when grown in media containing 1% horse serum. Lowering the serum concentration did not alter the dolichol-phosphate mannosyltransferase activity in D-1 which remained at low levels compared to L6. The incorporation of [3H]mannose in D-1 was found to be 60% of L6 in 10% serum whereas in 1% serum the incorporation into D-1 was further reduced to 30% of L6. [3H]mannose-labeled ConA-binding proteins isolated from L6 were quantitatively and qualitatively similar in cells grown in either 10 or 1% serum. However, in D-1 cells a further decrease in the ConA-binding ability of these glycoproteins was observed. Biochemical differentiation also occurs in D-1 upon fusion in 1% serum as seen by the increase in mRNA levels of the muscle-specific markers myosin light chain and troponin T. These results suggest the high-mannose type of oligosaccharides may not be involved in myoblast differentiation.
Clarke
E
E
Department of Biochemistry, Faculty of Medicine, University of Western Ontario, London, Canada.
Nandan
D
D
Brickenden
A
A
Cates
G A
GA
Ball
E
E
Sanwal
B D
BD
D000818:Animals; D001769:Blood; D002454:Cell Differentiation; D002459:Cell Fusion; D002460:Cell Line; D003208:Concanavalin A / Q000378:metabolism / Q000494:pharmacology; D003470:Culture Media; D006020:Glycopeptides / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism*; D008358:Mannose / Q000378:metabolism; D008364:Mannosyltransferases / Q000378:metabolism; D009132:Muscles / Q000166:cytology* / Q000378:metabolism; D009154:Mutation; D009218:Myosins / Q000235:genetics; D011134:Polysaccharides / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D011952:Receptors, Concanavalin A / Q000378:metabolism; D014336:Troponin / Q000235:genetics
D003470:Culture Media; D006020:Glycopeptides; D006023:Glycoproteins; D011134:Polysaccharides; D012333:RNA, Messenger; D011952:Receptors, Concanavalin A; D014336:Troponin; C027774:concanavalin A-binding glycoproteins; D003208:Concanavalin A; D008364:Mannosyltransferases; C022755:dolichyl-phosphate beta-D-mannosyltransferase; D009218:Myosins; D008358:Mannose