中波紫外线辐射损伤角质形成细胞的p53信号传导通路研究

Study on the p53 signal pathway in keratinocytes damaged by ultraviolet B irradiation

目的探讨中波紫外线(UVB)辐射对角质形成细胞p53信号传导通路的影响。方法以20、60和120mJ/cm2UVB辐射培养的取自健康儿童包皮的正常人表皮角质形成细胞,应用RT-PCR和免疫印迹方法,分别从mRNA水平和蛋白质水平,检测分析UVB辐射后2h、24h和48h,p53及其下游分子MDM2、p21、Bax和GADD45的表达。结果不同剂量UVB辐射角质形成细胞后均可见p53表达水平持续性显著升高(P<0.05)。低剂量UVB辐射角质形成细胞后,MDM2、p21、GADD45升高不明显(P>0.05),Bax不表达;UVB辐射剂量升至60mJ/cm2后,MDM2于辐射后2h短暂性显著升高,p21和Bax持续性显著升高。结论UVB辐射激活了角质形成细胞的p53信号传导通路,p53下游分子的表达具有剂量依赖性和时相性。

Objective To study the p53 signal pathway in keratinocytes damaged by ultraviolet B （ UVB ） irradiation. Methods Cultured normal human epidermal keratinocytes isolated from the foreskins of healthy children were irradiated with UVB in a dose of 20, 60 and 120 mJ/cm2, respectively. The mRNA and protein expression of p53 and its downstream molecules p21, mouse double minute 2 （ MDM2 ）, Bax, and growth arrest and DNA damage induced gene 45 （ GADD45 ） was detected by reverse transcription - PCR and Western blotting at 0, 2, 24, and 48 h after the irradiation. Results The mRNA and protein expression of p53 increased significantly at 2 h after UVB irradiation, and the increase continued until 48 h after the irradiation. None of the p53 effector genes （ MDM2, p21, GADD45 and Bax ） was transcriptionally induced significantly （ P 〉 0.05 ） after irradiation with low dose of UVB. When the dose of UVB reached 60 mJ/cm^2, the mRNA and protein expression of both p21 and Bax increased significantly （both P 〈 0.05 ） in a time-dependant manner, while those of MDM2 increased only transiently at 2 hrs after the irradiation. Conclusions UVB can trigger the activation of p53 signal pathway in keratinocytes. The expression of p53 downstream molecules is increased by UVB irradiation in a dose-and time-dependent manner in keratinocytes.