Abstract 537: Platelet Derived Growth Factor Induced Vascular Smooth Muscle Cell Proliferation is Associated with Enhanced Glut1 Expression/glycosylation and Glucose Uptake
Objective The role of glucose transporters (GLUTs) in the phenotypic regulation of vascular smooth muscle cells (VSMCs) has not been fully characterized. The present study has examined the effects of PDGF (vs insulin) on GLUT isoform expression/localization, GLUT1 glycosylation, glucose uptake and ATP formation during VSMC proliferation.
Methods Human aortic VSMCs were exposed to PDGF (30 ng/ml) or insulin (1 μM) for different time intervals. GLUT isoform expression was determined by qPCR and immunoblot analysis. GLUT isoform distribution/localization was determined by subcellular fractionation studies and immunocytochemical analysis. Glucose utilization and ATP formation were determined by glucose oxidation assay and luminescent ATP detection assay, respectively. The role of GLUT1 in VSMCs was determined by GLUT1 siRNA knockdown studies.
Results Exposure of VSMCs to PDGF resulted in significant increases in glucose uptake and cell proliferation, compared with insulin. In addition, PDGF and insulin enhanced the mRNA expression levels of total GLUT isoforms (GLUT1 through 14) to ~4317/105 B2M transcripts and ~8,174 transcripts/105 B2M transcripts, respectively, compared with control (~3259 transcripts/105 B2M transcripts). In particular, PDGF and insulin enhanced GLUT1 mRNA to 1711 ± 38/105 B2M transcripts and 3387 ± 58 transcripts/105 B2M transcripts, respectively. Immunoblot analysis using whole cell homogenates showed a significant increase in GLUT1 protein expression in PDGF or insulin-treated VSMCs. Importantly, subcellular localization studies using PDGF-treated VSMCs revealed enhanced GLUT1 protein expression and its glycosylation in the plasma membrane. Furthermore, PDGF enhanced glucose metabolism as revealed by increased glucose utilization and ATP formation. Down regulation of GLUT1 using target-specific siRNA significantly attenuated PDGF-induced glucose uptake.
Conclusions Enhanced expression and glycosylation of plasma membrane-localized GLUT1 isoform plays a major role in promoting VSMC proliferation, which may contribute to accelerated atherosclerosis.
- © 2013 by American Heart Association, Inc.