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. 2012 Dec 5;288(3):1774–1784. doi: 10.1074/jbc.M112.419887

FIGURE 4.

FIGURE 4.

Identification of functional Sp1 sites within human XT-I promoter. A, chondrocyte cells were transfected with pGL-XT-I (−1740/+85) reporter construct and then treated or not with 1 μm WP631 (Sp1 binding inhibitor). Twenty four hours later, cell extracts were assayed for luciferase activity. Relative luciferase activity is calculated as fold change over that of untreated cells. Data are expressed as mean ± S.D. of three separate experiments (*, p < 0.05). B, point mutation analysis showing Sp1 site-dependent transcriptional activity of the XT-I promoter in chondrocytes. Luciferase activity of the wild-type (WT) and its mutant construct (mSp1–125 and mSp1–40) was measured in chondrocytes treated (12 h) with IL-1β or vehicle. Relative luciferase activity is calculated as fold change over that of WT in untreated cells. In IL-1β-treated cells, relative luciferase activity was determined as fold activation over that of untreated cells. Data are expressed as mean ± S.D. of three separate experiments (*, p < 0.05).