The uptake of glucose into most eucaryotic cells is accomplished by sterospecific facilitated transport. A major effect of insulin on the disposal of blood sugar in humans involves activation of transport in insulin-responsive target tissues. Conversely, in both Type I and Type II diabetes mellitus there is a defect in the ability of insulin to increase hexose transport. Glucose flux is also modulated by dietary factors, obesity and oncogenic transformation. Mediating transport across the plasma membrane is an integral membrane glycoprotein that has been best characterized in the human erythrocytes. Though it is clear that numerous physiological manipulation affect both the total cellular content of transporter protein as well as its distribution among intracellular compartments, the mechanisms underlying these changes are unknown. In particular, there is no information on the structure or regulation of expression of the transporter gene. The first and major aim of these proposed studies it to obtain and amplify the cDNA and gene encoding the human glucose transporter. The cloning strategy will be to use antisera prepared against the purified human erythrocyte transporter for both hybrid selection and screening of a procaryotic expression library, as well as screening of the library by hybridization to oligodeoxynucleotides synthesized on the basis of amino acid sequence. Once the cDNA has been characterized, it will be used to study the regulation of transporter mRNA by insulin, nutritional factors, and oncogenic transformation. This will be correlated with changes in carrier protein biosynthesis, distribution and degradation as determined by immunoprecipitation with specific antibodies. Thus, by a combined approach of molecular biology, cell biology and protein chemistry, these studies should provide important new information about the gene encoding a membrane transport system and its regulation during insulin treatment and oncogenic transformation.
| Hiraki, Y; Rosen, O M; Birnbaum, M J (1988) Growth factors rapidly induce expression of the glucose transporter gene. J Biol Chem 263:13655-62 |
