FIGURE 7.

HDAC5 can down-regulate the GLUT4 promoter in the presence of GEF and MEF2A. 3T3-L1 pre-adipocytes or adipocytes differentiated to day 6 were transiently transfected with luciferase reporter plasmids–895-hG4-luc (firefly luciferase, for promoter activity) and pRLTK (Renilla luciferase, for transfection efficiency), as well as plasmids encoding GEF, MEF2A, and HDAC5 (+ indicates inclusion in transfection). Luciferase assays were performed after 24 h; specific activation of the –895-hG4 promoter was calculated from the ratio of firefly to Renilla luciferase activities. GEF and MEF2A did not increase hGLUT4 promoter activity in pre-adipocytes. GEF and MEF2A statistically significantly increased–895-hG4 promoter activity in day 6 adipocytes; HDAC5 significantly decreased promoter activity in the presence of GEF and MEF2A in these cells. (Day 0 preadipocytes, n = 2; day 6 adipocytes, n = 3, shown are mean ± S.E.).