Research Paper Volume 10, Issue 2 pp 212—228

Ultraviolet A irradiation induces senescence in human dermal fibroblasts by down-regulating DNMT1 via ZEB1

Figure 4. UVA irradiation regulates transcription factor ZEB1 via ROS. (A) ZEB1 mRNA (a) and protein (b) expression, assessed by real-time PCR and Western blotting, respectively, in irradiated and non-irradiated HDFs. Experiments were performed in triplicate. Intracellular ROS levels were assessed by measuring dichlorofluorescein (DCF) in triplicate experiments. * vs control, P < 0.05. (B) Following treatment with N-acetyl-L-cysteine (NAC), the expression of ZEB1, p53, p21, and p16 was assessed at the protein (a) and mRNA (b) levels. Experiments were performed in triplicate. * vs control or UVA, P < 0.05; Senescence-associated β-galactosidase (SA-β-gal) activity was assessed to evaluate cellular senescence after NAC treatment. In each condition the number of SA-β-gal-positive cells were counted (c, d; scale bar=200 µm). Experiments were performed in triplicate. * vs control or UVA, P < 0.05; Western blots images (left panels) and quantitative analysis (right panels) are representative of three independent experiments.