CREB1 Transcriptionally Activates LTBR to Promote the NF-κB Pathway and Apoptosis in Lung Epithelial Cells

Figure 4

CREB1 transcriptionally activates LTBR. (a–c) Protein bands of CREB1 and LTBR in A549 and ATII cells under the condition of normoxia or hyperoxia and their corresponding quantitative graphs. (d) A ChIP assay was conducted in A549 and ATII cells. Relative enrichment of LTBR promoter in anti-CREB1 was assessed by PCR analysis. (e) A luciferase reporter assay was conducted in HEK-293 T tool cell line. Luciferase reporter vectors containing LTBR promoter fragments at sites of -100~50, -350~50, -600~50, -850~50, and -1100~50 were used. The empty luciferase reporter vector served as a control. (f) A schematic map to show the potential binding of CREB1 on LTBR gene promoter. Two DNA motifs of CREB1 were exhibited above CREB1. (g) A luciferase reporter assay was conducted in A549 and ATII cells. Luciferase reporter vectors containing wile type LTBR promoter sequences (-1100~50), LTBR promoter mutated A sequences (-1100~50, with GACGC mutated into CGACA in -969~ -965), LTBR promoter mutated B sequences (-1100~50, with GGATGG mutated into CATCCC in -593~ -588), and LTBR promoter mutated A + B sequences were used. (h) A luciferase reporter assay was conducted in A549 and ATII cells. Luciferase reporter vectors containing site 1 and site 2 and their flanking sequences were used. , .

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