Transient transfection-reporter assay of the effect of RXRγ on Glut1 promoter.
(A) Glut1-Luc plasmid, with or without RXRγ and/or PPARδ expression vectors, was transfected into the quadriceps muscle of C57BL6 mice. Activation of the luciferase reporter gene was measured in relative light units and normalized to dual luciferase activity. Mean values from experiments (n = 5) are shown as fold induction, where the activity in the absence of RXRγ is the reference value (set at 100). (B) Schematic representations of serial deletion of Glut1 promoter constructs are shown in the figure. Squares denote the putative PPAR/RXR binding sites. Open bars; Glut1-Luc without RXRγ and PPARδ expression vectors, and filled bars; Glut1-Luc with RXRγ and PPARδ expression vectors. The activity in the absence of RXRγ and PPARδ in each experiment for different Glut1-Luc construct in the reference value (set at 100). ** P<0.01, compared with the value of wild-type promoter in the absence of RXRγ/PPARδ.