Fibronectin-induced VEGF receptor and calcium channel transactivation stimulate GLUT-1 synthesis and trafficking through PPARγ and TC10 in mouse embryonic stem cells

Extracellular matrix (ECM) mediates interactions between integrin and growth factor receptor (GFR) or ion channel. Although this crosstalk promotes integration of the downstream signal pathways and then regulates cellular function, the effect of ECM on glucose transporter (GLUT) in stem cells has not been elucidated. Therefore, we examined the effect of fibronectin on GLUT-1 expression, trafficking, and its related signal pathways in mouse embryonic stem cells (mESCs). Fibronectin increased 2-deoxyglucose (DG) uptake and GLUT-1 protein expression that were blocked by transcription or translation inhibitors. Integrin alpha 5 beta 1-bound fibronectin increased 2-DG uptake through cluster formation with vascular endothelial growth factor receptor (VEGFR) 2, and then activated Ras and PI3K/Akt. In another pathway, integrin alpha 5 beta 1 displayed structural and functional interactions with calcium channels, and stimulated 2-DG uptake through calcium influx and PKC activation. Akt and PKC-induced PPAR gamma phosphorylation enhanced the decreased expression of PPAR gamma protein, and subsequently increased GLUT-1 protein synthesis and 2-DG uptake. Fibronectin stimulated TC10 activity and cytoskeleton (F-actin) rearrangement, followed by GLUT-1 trafficking. In conclusion, integrin-bound fibronectin stimulates GLUT-1 synthesis through VEGFR2/Ras/PI3K/Akt and calcium channel/Ca2+/PKC, which are merged at PPAR gamma and GLUT-1 trafficking through TC10 and F-actin. (c) 2013 Elsevier B.V. All rights reserved.