Hexose specificity for downregulation of HepG2/brain-type glucose transporter gene expression in L6 myocytes
| Autor: | Leonard C. Harrison, Frances Maher |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
medicine.medical_specialty
Snf3 Time Factors Monosaccharide Transport Proteins Endocrinology Diabetes and Metabolism Glucose uptake Down-Regulation Biology Deoxyglucose Tritium Cell Line chemistry.chemical_compound Internal medicine Internal Medicine medicine Glutamate aspartate transporter Animals Insulin Hexose RNA Messenger Hexoses chemistry.chemical_classification Dose-Response Relationship Drug Muscles Glucose transporter Transporter Metabolism Blotting Northern Rats Endocrinology Glucose chemistry Biochemistry Gene Expression Regulation Galactose biology.protein |
| Zdroj: | Diabetologia. 33(11) |
| ISSN: | 0012-186X |
| Popis: | Glucose deprivation of L6 myocytes results in the upregulation of glucose transporter activity, protein and mRNA. We have investigated the downregulation of transporter gene expression by glucose and other hexoses in glucose-deprived L6 myocytes. Glucose transport activity was measured as the uptake of 3H-2-deoxyglucose. Transporter protein and mRNA were detected by immunoblot and Northern blot analysis, respectively, with probes to the rat brain glucose transporter. Glucose deprivation of myocytes, in the absence and presence of insulin, increased 3H-2-deoxyglucose uptake, transporter protein and mRNA levels. Refeeding with glucose reversed the glucose deprivation effects on transport activity and mRNA within 12 h, with half-maximal effects at 1–2 mmol/l glucose. Mannose fully substituted for glucose. Refeeding with the non-metabolisable glucose analogues 2-deoxyglucose and 3-0-methylglucose, or with glucosamine or mannitol, downregulated 3H-2-deoxyglucose uptake but had little or no effect on transporter protein and mRNA expression. In contrast, glucose-6-phosphate markedly increased 3H-2-deoxyglucose uptake but partly downregulated transporter mRNA levels, whereas galactose had a small stimulatory effect on both 3H-2-deoxyglucose uptake and transporter mRNA; neither affected transporter protein levels. The transporter mRNA level was not affected by several metabolites (pyruvate, glyceraldehyde, glycerol) and amino acids (alanine, glutamine). These findings indicate that (i) there are independent pathways for hexose regulation of transport activity, protein and mRNA and (ii) down-regulation of transporter mRNA requires metabolism beyond hexose phosphate whereas glucose uptake may be regulated by direct interaction of hexoses with the transporter. |
| Databáze: | OpenAIRE |
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