Regulation of glycolipid synthesis during differentiation of clonal murine muscle cells

The two clonal murine muscle cell lines G7 and G8, originally derived from the M114 line 20], represent unique models for comparative studies of myogenesis. Glycolipid synthesis was examined during differentiation using ³H]-galactose and ³H]-glucosamine as precursors. Upon G7 contact glucosylceramide labeling increased and nLcOse₅Cer labeling stopped. During membrane fusion, glucosylceramide labeling stopped and lactosylceramide became the major synthetic product. G8 cells presented a different pattern, with increased labeling of GbOse₃Cer during myogenesis. The major ganglioside synthesized by both myoblasts was GM3, and more complex structures were observed following completion of myotube formation. Total glycopeptide labeling increased when G8 myoblasts fused and remained elevated in myotubes, whereas no differences during fusion of G7 cells were noted. Upon comparison of the two clonal lines, the only consistent observation was a significant increase in the synthesis of total gangliosides and neutral glycolipid during cell contact and membrane fusion (p < 0.02). The results suggest that changes in the synthesis of specific glycolipid structures during myogenesis are unique to each muscle cell line examined. However, transient increases in synthesis of total myoblast gangliosides and neutral glycolipids may be a more general phenomenon, possibly by curbing proliferation or by altering myoblast membrane fluidity characteristics during differentiation.Abbreviations MG6 VI³NeuAc-V⁴Gal-IV³GlcNAc-nLcOse₄Cer - TLC thin-layer chromatography - HPTLC high performance thin-layer chromatography - Gal galactose - GlcNH glucosamine - PBS phosphate buffered saline - CK creatine kinase