Regulation of hexose transporters of chicken embryo fibroblasts during glucose starvation
Tillotson, L.G.; Yamada, K.; Isselbacher, K.J.
Federation Proceedings 43(8): 2262-2264
1984
ISSN/ISBN: 0014-9446 PMID: 6325251 Document Number: 229663
Chicken embryo fibroblasts (CEF) when exposed to glucose-deficient culture medium developed 4- to 10-fold increased hexose transport activity within a few hours. Plasma membrane fractions prepared from starved and fed CEF revealed that starved cell membranes had a threefold greater glucose transport activity and [superscript 3H]cytochalasin B binding. The close correlation between transport activities of whole CEF and plasma membrane fractions indicates that hexose transport regulation during starvation results primarily in an increase in the number of functioning hexose transporters. The effect of protein synthesis inhibition on the overall process was studied with emetine, an inhibitor of translational elongation. Glucose-fed CEF treated with low concentrations of emetine, 0.1 mu M, showed a loss of transport greater than 65% within 4 h, but with 10 mu M emetine there was no significant effect. Emetine treatment (0.1 to 10 mu M) of CEF undergoing starvation virtually blocked any increase in transport whereas treatment of starved CEF led to only a slight loss of transport. Starved CEF refed with glucose had a decline of transport that was potentiated by low concentrations of emetine (0.1 mu M); under these conditions high concentrations of emetine (10 mu M) largely prevented loss of transport.