Hexosamines are unlikely to function as a nutrient-sensor in 3T3-L1 adipocytes: a comparison of UDP-hexosamine levels after increased glucose flux and glucosamine treatment
| Autor: | Remko R. Bosch, Cees J. Tack, André J. Olthaar, C.G.J. Sweep, Ad R. M. M. Hermus, Marie-Jose J. Pouwels, Paul N. Span |
|---|---|
| Rok vydání: | 2004 |
| Předmět: |
Uridine Diphosphate Glucose
medicine.medical_specialty Endocrinology Diabetes and Metabolism Glucose uptake medicine.medical_treatment Vascular medicine and diabetes [UMCN 2.2] Deoxyglucose Biology Mice chemistry.chemical_compound Endocrinology Insulin resistance Glucosamine 3T3-L1 Cells Diabetes mellitus Internal medicine Adipocytes medicine Animals Insulin chemistry.chemical_classification Uridine Diphosphate N-Acetylglucosamine Endocrinology and reproduction [UMCN 5.2] Hexosamines 3T3-L1 medicine.disease carbohydrates (lipids) Glucose chemistry Uridine Diphosphate N-Acetylgalactosamine Uridine diphosphate glucose Insulin Resistance |
| Zdroj: | Endocrine, 23, 17-24 Endocrine, 23, 1, pp. 17-24 |
| ISSN: | 1355-008X |
| Popis: | Contains fulltext : 58301.pdf (Publisher’s version ) (Open Access) Whether the hexosamine biosynthesis pathway acts as a nutrient-sensing pathway is still unclear. Glucose is directed into this pathway by GFAT. Because the activity of GFAT is tightly regulated, we examined whether UDP-hexosamine levels can increase significantly and dose-dependently in response to elevated glucose concentrations. In glucosamine-treated 3T3-L1 adipocytes, inhibition of insulin-stimulated glucose uptake was highly correlated with UDP-hexosamine levels (r = -0.992; p < 0.0001 for UDP-GlcNAc and r = -0.996; p < 0.0001 for UDP-GalNAc). Incubation of 3T3-L1 adipocytes with 0.1 microM insulin for 24 h in medium containing 1 and 5 mM glucose increased the rate of glucose uptake by 365% and 175% compared to untreated cells, respectively. This increase was not observed when the cells were incubated for 24 h with insulin in medium containing 10 or 25 mM glucose. However, treatment of cells with insulin and 1, 5, 10, or 25 mM glucose resulted in similar increases in levels of UDP-GlcNAc and UDP-GalNAc that always amounted to approx 30-40% above baseline values. This led us to conclude that despite exposure of adipocytes to conditions of extreme and prolonged glucose disposal, the increases in cellular UDP-hexosamines were minimal and not dependent on the extracellular glucose concentration. Taken together, our results are in line with the hypothesis that in glucosamine-treated adipocytes UDP-hexosamines influence insulin-stimulated glucose uptake. However, our observations in glucose-treated adipocytes argue against the possibility that UDP-hexosamines function as a nutrient-sensor, and question the role of the hexosamine biosynthesis pathway in the pathogenesis of insulin resistance. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full text from SpringerLink