| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1998: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1997: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Research Abstract |
We earlier developed a novel method to detect translocation of the glucose transporter (GLUT), derectly and simply using c-myc epitopr-tagged GLUT (GLUTmyc). To define the effect of platelet-derived growth factor (PDGF) on glucose transport in 3T3-L1 adipocytes, we investigated the PDGF- and insulin-induced glucose uptake, translocation of glucose uptake by 9-10-fold and 5.5-6.5-fold, respectively, in both 3T3-L1 and 3T3-L1GLUT4myc adipocytes. Exogenous GLUT4myc expression led to enhanced PDGF-induced glucose transport. In 3T3-L1GLUT4myc adipocytes, insulin and PDGF induced an 3-fold and 5-fold increase in GLUT4myc translocation, respectively, determined in a cell surface anti-c-myc antibody binding assay. This PDGF-induced GLUT4myc translocation was further demonstrated with fluorescent detection. In contrast, PDGF stimulated a 2-fold increase of GLUT1myc translcoation and 2.5-fold increase of glucose uptake in 3T3-L1GLUT1myc adipocytes. The PDGF-induced GLUT4myc translocation, glucose uptake and PI 3-kinase activity were maximal (100%) at 5-10 min, and thereafter rapidly declined to 40%, 30%, and 18%, respectively, within 60 min, a time when effects of insulin were maximal. Wortmannin (0.1 mM) abolished PDGF-induced GLUT4myc translocation and glucose uptake in 3T3-L1GLUT4myc adipocytes. These results suggest that PDGF can transiently trigger the trasnlocation of GLUT4 and stimulates glucose uptake by translocation of both GLUT4 and GLUT1 in a phosphatidylinositol 3-kinase-dependent signaling pathway in 3T3-L1 adipocytes.
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