中文摘要：

研究let-7a在UVB照射后的人角质细胞HaCaT中的表达。HaCaT细胞受UVB照射后继续培养2h、4h、8h、12h、24h，用real-timeqPCR检验let-7a的表达水平。利用在线数据库PicTar等预测靶基因并用Gostat软件对靶基因进行功能分类。结果发现let-7a在照射后12h出现表达水平的高峰（大于7倍），而在其它时间点没有改变。在对其靶基因预测后用Gostat进行功能分类后发现，casp3、bc1212、map3kl和cdk5等基因同时也是UVB诱导的细胞周期调节的靶基因。这些结果提示let-7a可能在UVB致损伤的机制中起关键作用。

英文摘要：

In order to study the expression level of let-7a in HaCaT exposed to UVB real-time qPCR was used to detect the expression level of let-7a at 2 h, 4 h, 8 h, 12 h and 24 h after UVB irradiation. Online database PicTar can be used to predict the targets of let-7a and performed function categories with softerware Gostat. The results show that the expression level of let-7a at 12h is higher than that at other time points with more than 7 times. The target prediction and Gostat analysis indicate that casp3 、 bc1212 、 map3kl and cdk5 may be UVB-induced target genes of cell cycle regulation. These results suggest that let-7a may play a key role in the mechanism of UVB-induced injury.