AJP - Cell Physiology, Vol 261, Issue 6 C973-C979, Copyright © 1991 by American Physiological Society
Permanent hexose transport upregulation in a respiration-deficient human fibroblast cell strain
S. Andrejchyshyn, L. Continelli and R. J. Germinario
Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, Canada.
The regulation of hexose transport was studied in a human diploid
fibroblast respiration-deficient cell strain (WG750). Transport of
2-deoxy-D-glucose (2-DG) was greater than sixfold higher compared with an
in vivo age-matched normal cell strain (MCH55). In addition,
3-O-methylglucose transport and 14CO2 production were elevated in the
mutant cell strain. Kinetic analysis revealed that the increased sugar
transport in mutant cells was due to an average 5.7-fold increase in the
2-DG maximal transport rate, with no observed differences in the transport
Michaelis constant for both normal and mutant cells. Also, the inhibitor
constants for D-glucose inhibition of 2-DG transport were nearly identical
for both cell types. Glucose deprivation led to a similar time-dependent
increase in hexose transport in both cell strains. Serum refeeding of
glucose-fed serum-deprived cultures led to a progressive increase in 2-DG
transport in normal cells, whereas mutant cells displayed a time-delayed
increase in 2-DG transport. Exposure to 67 and 670 nM insulin stimulated
2-DG transport on average 1.99 +/- 0.25- and 2.33 +/- 0.26-fold,
respectively, over basal transport in the normal cells, whereas the mutant
cells were significantly less sensitive to the stimulatory effects of the
hormone. Insulin binding and amino acid transport (i.e.,
alpha-aminoisobutyric acid uptake) in the normal and mutant cells were not
different. Data obtained using Western blot analysis showed that WG750
(mutant) cells expressed an increase (approximately 4-fold) in total
cellular HepG2 (erythroid-brain) transporter protein compared with normal
cells, thus reflecting the changes seen in hexose transport.(ABSTRACT
TRUNCATED AT 250 WORDS)
