Figure 6.

YY1 binds to PGC-1β promoter and enhances its transcription independently of HIF-1α. A. Schematic diagrams of the predicted YY1 binding site in PGC-1β promoter and the luciferase reporter bringing PGC-1β promoter (PGC-1β-Luc). B-C. The activity of PGC-1β-Luc in YY1-silenced (B) and YY1-overexpressed (C) HepG2 cells cultured under normoxic condition, as analyzed by using dual luciferase assay (n = 3). D. Schematic diagram of firefly luciferase reporter bringing the PGC-1β promoter lacking YY1 binding site (PGC-1βdel-Luc). E-F. The activities of PGC-1β-Luc and PGC-1βdel-Luc in YY1-silenced (E) and YY1-overexpressed (F) HepG2^HIFnull cells cultured under hypoxic condition, as analyzed using dual luciferase assay (n = 3). G. Binding of YY1 to the promoter region of PGC-1β in HepG2 cells as examined using chromatin immunoprecipitation assay with anti-YY1 antibody followed by PCR. Location of the primer set (top) and the length of the amplicon (bottom) are shown. H. Schematic diagram of the firefly luciferase reporter bringing PGC-1β promoter with mutated predicted YY1 binding site (PGC-1β^Mut-Luc). Wild-type nucleotides are shown in black, and mutated ones are shown in gray. I-J. The activities of PGC-1β-Luc and PGC-1β^Mut-Luc in YY1-silenced (I) and YY1-overexpressed (J) HepG2^HIFnull cells cultured under hypoxic condition, as analyzed using dual luciferase assay (n = 3). Cells transfected with shCon or pcCon were used as controls. Quantification data are shown as mean ± SEM of three independent experiments. pcCon: pcDNA3.1(+); **P < 0.01; NS: not significant (ANOVA).