Figure 3.

Expression of continuously up-regulated genes after UVB exposure. A: Four genes were significantly up-regulated at both 3 and 24 hours after UVB exposure. Relative expression levels were determined by real-time quantitative PCR. Each of the two groups of RNAs isolated from wild-type and Ogg1 knockout mice was assayed in duplicate. Reactions were normalized to GAPDH expression levels. *P < 0.05; **P < 0.01; and ***P < 0.001. B: Immunohistochemical study of versican expression after UVB irradiation. Versican is barely expressed in the wild-type mouse epidermis and dermis in the absence of UVB irradiation. At 24 hours after UVB exposure, versican was expressed in the wild-type epidermis. In Ogg1 knockout mice at 24 hours, versican was strongly expressed in the epidermis (arrowheads), as well as in dermal fibroblasts (arrows). Positive signals are seen as reddish-brown deposits produced on reaction with the 3-amino-9-ethylcarbazole substrate. Scale bar = 30 μm. C: Versican expression after UVB exposure, as determined by Western blotting. Versican was more strongly up-regulated in Ogg1 knockout than in wild-type mice at 24 and 48 hours after UVB exposure. This up-regulation was time-dependent. The band at approximately 75 kDa indicates that the antibody for versican can detect the V1 isoform. α/β-Tubulin was used as the loading control. Data are representative of three separate determinations.