p55PIK Transcriptionally Activated by MZF1 Promotes Colorectal Cancer Cell Proliferation
Figure 2
Transcription factor MZF1 binds on site of 5′ end of p55PIK, inducing p55PIK promoter activity. (a) Analysis of the −1243/−840 region, which affects main p55PIK promoter activity and transcription. Several transcription factors, including MZF1, YY1, Runx1, ADR1, IRF1, Delta1, or p300, bind on corresponding domains within p55PIK promoter. (b, c) Relative luciferase activity (RLA) at 24 h after-transfection of a series of mutant constructs of p55PIK reporter plasmids (−1243/+45)-p55PIK, named MZF1-mut1, MZF1-mut2, MZF1-mut3, YY1-mut, and RUNX1-mut are transfected into HepG2 or HeLa cell lines. Data are shown as mean SD (; , per Student’s -test). (Data of ADR1-mut, IRF1-mut, Delta1-mut, p300-mut1, and p300-mut2 are not shown). (d) Sequencing of mutant MZF1-mut1, showing mutagenesis from TGGGGA to CTAGTG at the −901/−896 site, of p55PIK reporter plasmids (−1243/+45)-p55PIK. Sequencing data show that associated binding site was mutated successfully on (−1243/+45)-p55PIK reporter plasmids (data not shown). (e) Transcription factors MZF1 bind to p55PIK promoter region. Chromatin immunoprecipitation (ChIP) assay was used to detect binding between MZF1 protein and TGGGGA sequence located at −901/−896 site of p55PIKpromoter in colon cancer cells and resected tissues.
