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. 2010 Dec 6;286(6):4809–4818. doi: 10.1074/jbc.M110.152900

FIGURE 4.

FIGURE 4.

The activation of the OSE1 promoter region mediated by ATF4 is inhibited in Perk−/− osteoblasts. A, scheme of the promoter region of mouse OG2 (Ocn promoter) that includes the OSE2 (Runx2 binding site) and OSE1 (ATF4 binding site) regions. B, reporter assays using the OG2 promoter. Primary osteoblasts were transfected with the OG2 reporter construct and treated with or without BMP2 (100 ng/ml). In Perk−/− osteoblasts treated with BMP2, the reporter activities were reduced when compared with WT osteoblasts. Data are presented as the ratio of firefly luciferase activities to Renilla luciferase activities (mean ± S.D., n = 3, *, p < 0.05, ***, p < 0.001; Student's t test). C, reporter assays using OG2 promoter and indicated constructs. The reporter activities were observed to increase upon exposure to TG (1 μm) in WT primary osteoblasts but not in Perk−/− osteoblasts. Note that the reporter activities increased significantly when ATF4 was introduced to Perk−/− osteoblasts. The introduction of other CREB/ATF family members did not induce the reporter activities (mean ± S.D., n = 3, **, p < 0.01; Student's t test). D, reporter assays using OG2-OSE1 and OG2-OSE2. The reporter activities of WT primary osteoblasts transfected with the OG2-OSE1 reporter were induced by exposure to TG (1 μm) but not with OSE2 (mean ± S.D., n = 3, *, p < 0.05, **, p < 0.01; Student's t test). OASIS (Old Astrocyte Specifically Induced Substance).