EXPRESSION OF THE BRAIN-TYPE GLUCOSE TRANSPORTER IS RESTRICTED TO BRAIN AND NEURONAL CELLS IN MICE

Northern blot analysis of human tissues has demonstrated the expressio n of the brain-type glucose transporter isoform (GLUT 3) in liver, mus cle and fat, raising the possibility that this transporter isoform may play a role in the regulation of glucose disposal in these tissues in response to insulin. We have raised an anti-peptide antibody against the C-terminal 13 amino acids of the murine homologue of this transpor ter isoform, and determined its tissue distribution in mouse tissues a nd murine-derived cell lines. The antibodies recognise a glycoprotein of about 50 kilodaltons, expressed at high levels in murine brain. In contrast to human tissues, the expression of GLUT 3 in mice is restric ted to the brain, and no immunoreactivity was observed in either liver , fat or muscle membranes, or in murine 3T3-L1 fibroblasts or adipocyt es. In contrast, high levels of expression of this isoform were observ ed in the NG 108 neuroblastoma x glioma cell line, a hybrid cell deriv ed from rat glioma and mouse neuroblastoma cells. Taken together, thes e data suggest that the expression of GLUT 3 in rodents is restricted to non-insulin responsive neuronal cells and hence it is likely that t he factors regulating the expression of this transporter in rodents di ffer to those in humans.