Abstract:

Objective To investigate the expression changes of aspartic proteinase （cathepsin D） and cysteine proteinase （cathepsin K） in photoaged fibroblasts. Methods The senescence of human fibroblasts was induced via culture in the presence of 8-methoxypsralen （MOP） of 50 mg/L in darkness for 24 hours followed by irradiation with UVA of 80 kJ/m2. Then, aged fibroblasts were confirmed by senescence-associated β-galactosidase （SA-β-gal） staining. Real-time RT-PCR and Western blot were carried out to detect the mRNA and protein expressions of cathepsin D and cathepsin K in photoaged and normal control fibroblasts, respectively. Results Western blot showed a significant difference between photoaged and control fibroblasts in the grey scale of cathepsin D and cathepsin K （3.25 ± 0.33 vs 14.18 ± 2.25, t = 30.61, P < 0.01; 2.39 ± 0.66 vs 29.38 ± 4.62, t = 12.63, P < 0.01）. The ΔCt values for cathepsin D and cathepsin K mRNA were 2.79 ± 0.17 and -0.92 ± 0.06, respectively, in photoaged fibroblasts, significantly lower than those in the control fibroblasts （4.54 ± 0.34, 2.57 ± 0.13, t = 20.78, 28.50, respectively, both P < 0.01）. According to the value of 2-ΔΔCt, the expression of cathepsin D and cathepsin K mRNA decreased 0.24 ± 0.021 and 0.09 ± 0.005 folds, respectively, in photoaged fibroblasts compared with the control fibroblasts. Conclusion The expression of cathepsin D and cathepsin K is decreased in photoaged fibroblasts.

Key words: fibroblasts