Figure 2. MafA, MafB and cMaf can activate insulin and glucagon expression.
A, Luciferase reporter plasmids (-238 WT LUC or -122.121m LUC) were transfected into HeLa cells with the indicated expression plasmids (pcDNA3.1, MafA, MafB or cMaf). Luciferase activity was determined 48 h after transfection. Results are presented relative to the activity of -238 WT luciferase construct transfected with pcDNA3.1 ± SE (n = 4). B, Luciferase reporter plasmid (-238 WT LUC) and indicated expression plasmid were transfected into HeLa cells with or without NMafA plasmid that lacks N-terminal activation domain. Results are presented as in (a) (n=3). C, Glucagon Luciferase reporter plasmid [-2.2 Glucagon LUC, (Lee et al., 1992)] and indicated expression plasmid were transfected into HeLa cells with or without NMafA plasmid. Results are presented as in (a) (n=3). Rat glucagon: GFP reporter plasmid was transfected into HeLa cells with (D) MafA, (E) MafB, (F) cMaf (G) ΔNMafA expression plasmids or (H) pcDNA3.1. 48 h after transfection, HeLa cells were immunostained to detect GFP (green), nuclei (DAPI blue) and Maf factors (Red), using anti- MafA (D and G), MafB (E), cMaf (F), and large-Maf (H) antibodies. Each figure shows combined three-color image, while the insets show signals from individual color channels. Magnification bar = 20 μm.