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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Transport regulation by different metabolizable and nonmetabolizable sugars was studied in human fibroblasts. Sugars were classed as glucose-like (D-mannose, 3-0-methyl-D-glucose, thio-D-glucose, and D-allose) and starvation-like (D-galactose, D-fructose, L-glucose, D-xylose, 6-deoxy-D-glucose and 2-deoxy-D-glucose) based on their competence in curbing glucose starvation enhanced transport. No significant correlation existed between the ability of a sugar to curb hexose transport and the KI of that sugar in inhibiting hexose transport. Independence of the transport curb from glucose metabolism was observed since nonmetabolizable analogs of D-glucose when substituted for D-glucose in the culture medium effected glucose [i.e. 3-0-methyl-D-glucose (3-OMG)] and starvation-like (i.e. 6- and 2-deoxy-D-glucose) effects. The KI of inhibition pf 2-deoxy-D-glucose transport for 3-OMG was 8.5 mM, similar to those obtained for 6-deoxyglucose and 2-deoxyglucose on 2-deoxyglycose transport (7.5 and 3.5 mM, respectively) and on 3-0-methylglucose transport (3.5 and 2.5 mM, respectively). An equimolar mixture of D-glucose and 3-OMG (5.55 mM each) was more effective than 11.1 mM D-glucose or 3-OMG alone in curbing hexose transport or reversing hexose starvation induced increases in transport. The effect of 3-OMG may be independent of glucose metabolism but it is possible that 3-OMG structurally mimics a metabolite of glucose that may interact with intracellular regulators of carrier degradation and or expression.
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PMID:Control of sugar transport in human fibroblasts independent of glucose metabolism or carrier-substrate interaction. 403 32

The regulation of hexose transport under glucose-starvation conditions was studied in cultured human skin fibroblasts. Glucose starvation enhanced the transport of 2-DG and 3-0-methyl-D-glucose (3-OMG) but not of L-glucose. Glucose-starvation enhanced transport was inhibited by cytochalasin B (10 microM). The starvation-induced change in 2-DG transport was due to an increase in the Vmax of both the high and low affinity transport sites (2.8- and 2.4-fold, respectively) with no effect on their Kms. The presence of 5.55 mM glucose, fructose, or L-glucose in the medium resulted in transport increases similar to those seen in glucose-starved cells, while the presence of 5.55 mM glucose, mannose, or 3-OMG repressed 2-DG transport. Glucose-starvation enhancement of 2-DG transport was blocked by cycloheximide (20 micrograms/ml) but not by actinomycin D (0.03 microgram/ml) or alpha-amanitin (3.5 microM). Readdition of glucose (5.55 mM) for six hours to glucose-starved cells led to a rapid decrease in hexose transport that could be blocked by cycloheximide but not actinomycin D. Although readdition of 3-OMG to glucose-starved cells had little effect on reversing the transport increases, glucose plus 3-OMG were more effective than glucose alone. Serum containing cultures (10% v/v) of glucose-fed or glucose-starved cells exhibited rapid decreases in 2-DG transport when exposed to glucose-containing serum-free medium. These decreases were prevented by employing glucose-free, serum-free medium. The data indicate that hexose transport regulation in cultured human fibroblasts involves protein synthesis of hexose carriers balanced by interactions of glucose with a regulatory protein(s) and glucose metabolism as they affect the regulation and/or turnover of the carrier molecules.
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PMID:Regulation of sugar transport in cultured diploid human skin fibroblasts. 618 50