C/ebpβ and Stat3 activate the FANCC promoter in myeloid cells.
A, alignment of the human and murine FANCC promoters identified conserved consensus sequences for Stat and C/ebp binding. The human sequence is shown in black and the murine in blue. Conserved regions are indicated in gray. The tandem Stat consensus is shown in purple and the C/ebp consensus in red. Truncations for reporter assays are indicated. B, Stat3 and C/ebpβ-Lap activate discrete regions of the FANCC promoter, but C/ebpβ-Lip and Stat5 do not influence FANCC promoter activity. U937 cells transfected with a 1-kb FANCC promoter construct or truncated derivatives thereof were co-transfected with DNA plasmids driving the expression of each of the three different transcription factors indicated. Reporter constructs with truncations of the FANCC promoter were assayed for the effect of overexpressed Stat3, Stat5, C/ebpβ (Lap or Lip isoform), Icsbp (positive control), or empty vector. Statistically significant differences are indicated by *, **, ***, #, or ## (p < 0.01, n = 6 for all comparisons). C, Stat3, C/ebpβ-Lap, and Icsbp are not redundant for FANCC promoter activation. The 1.0 kb of FANCC promoter/luciferase reporter construct was assayed in U937 transfectants for the effect of combinations of overexpressed Stat3, C/ebpβ (Lap), or Icsbp or shRNA knockdown of Stat3 or C/ebpβ. Some transfectants were differentiated with IL1β prior to analysis. Statistically significant differences are indicated by *, **, ***, #, or ## (p < 0.01, n = 6 for all comparisons).