Sox9 protects UVB- induced keratinocyte apoptosis.

<p>(A) Keratinocytes were treated with UVB at the indicated doses. Cells were refed with fresh medium and incubated for a further 24 h. Sox9 protein level was increased in a dose-dependent manner. (B) Effect of Sox9 overexpression on UVB-induced keratinocyte apoptosis. Keratinocytes were transduced with 10 MOI of adenovirus for overnight, washed twice with PBS, and incubated with fresh medium for 2 d. Then, cells were UVB-irradiated at the dose of 20 mJ/cm², then further incubated for 24 h. Apoptosis was detected by PARP cleavage. In Sox9 overexpressed group, cleaved PARP (lower band) is significantly reduced, indicating that Sox9 protects UVB-induced keratinocyte apoptosis. In Western blot with anti-Sox9 antibody, a band represents the exogenously expressed GFP-Sox9 fusion protein (∼82 kDa). In Western blot with anti-GFP antibody, upper band (arrow) indicates the GFP-fused Sox9 (∼82 kDa) and lower band (arrow head) indicates the GFP protein (∼26 kDa). (C) Knockdown of Sox9 by microRNA (miR). Keratinocytes were transduced with 10 MOI of adenoviruses expressing miR for Sox9 for overnight. After washing, cells were incubated for a further 2 d, and expression of Sox9 was detected by Western blot. Scrambled (Scr) miR was used for negative control. (D) Keratinocytes were transduced with adenovirus, then UVB-irradiated. Cell apoptosis was analyzed by TUNEL assay. Sox9 overexpression protects UVB-induced apoptosis, while Sox9 knockdown enhances UVB-induced apoptosis.