Journal of Lipid Research, Vol 19, 77-81, Copyright © 1978 by Lipid Research, Inc.
Effect of serum on ganglioside uptake and choleragen responsiveness of transformed mouse fibroblasts
PH Fishman, RM Bradley, J Moss and VC Manganiello
NCTC 2071 cells, transformed mouse fibroblasts, did not respond to
choleragen when grown in chemically defined medium. When grown in medium
containing 10 percent fetal calf serum, however, the cells accumulated
cyclic AMP upon exposure to the toxin. Gangliosides isolated from the fetal
calf serum were as effective as whole serum in inducing choleragen
responsiveness in the cells. The putative choleragen receptor, the
monosialo-ganglioside GM1, could not be detected by chemical analysis in
cells exposed to serum. 3H-Labeled GM1 was detected in these cells,
however, following sequential exposure to galactose oxidase and sodium
borotritide. Thus, uptake of minute amounts of GM1 from serum by these
cells sensitized them to choleragen.