电离辐射诱导小鼠小肠隐窝和绒毛的基因表达分析

Gene expression profiles in intestinal crypt and villus of mice after ionizing radiation injury

目的通过基因表达的芯片分析方法,观察电离辐射引起的小鼠小肠上皮隐窝和绒毛基因表达的改变,探讨隐窝细胞的DNA损伤和修复、细胞周期调控的特点。方法 20只5周龄C57/BL6小鼠雄性20～22 g,随机分组,对照组不经电离辐照,处理组经12 Gy电离辐射全身照射后,于4、8、24 h分离小肠隐窝和绒毛上皮细胞,用cDNA表达谱芯片分别检测隐窝和绒毛基因表达的动态变化,对上调或下调的基因进行聚类分析,并重点对DNA损伤修复相关和细胞周期相关基因进行分析。结果与对照组相比上调或下调2倍以上的基因(P<0.01)经聚类分析被归属为各细胞信号通路,其中主要涉及p53通路、MAPK通路、凋亡、细胞周期以及免疫反应(P<0.05),将P值排序发现p53通路、MAPK通路对隐窝的调控更为明显。各DNA修复途径代表基因在隐窝和绒毛中均有不同程度的上调表达,且与细胞周期的变化相一致。基因表达特点提示隐窝细胞以准确性高的方式(核苷酸外切修复、同源重组)进行DNA损伤修复,而绒毛细胞则以快速但易发生错误修复的方式(错配修复)恢复基因的完整性。结论 电离辐射诱导的DNA损伤反应与细胞分化程度相关,隐窝细胞对损伤更敏感。

Objective To investigate ionizing irradiation（IR）-induced overall changes of gene expressions in small intestinal crypt and villus of mice by gene expression chip analysis,and the characteristics of genes relative to DNA damage repair and cell cycle regulation.Methods Twenty male C57/BL6 mice,5-week-old and 20 to 22 g body weight,were randomly grouped.Experimental groups were sacrificed at 4,8,and 24 h after a single dose of 12 Gy cobalt total body irradiation（TBI）,followed by the separation of crypt and villus cells from small intestinal epithelium.Normal mice were taken as control.Dynamic changes of gene expressions were elucidated by cDNA expression microarray analysis.Upregulated and downregulated genes were subjected to cluster analysis,and the genes related with DNA damage repair and cell cycle were also analyzed.Results After IR treatment,the genes that were upregulated or downregulated for more than 2-folds（P〈0.01） compared with control were grouped into different cell signal pathways by cluster analysis.These pathways were mainly related with p53,MAPK,apoptosis,cell cycle and immune response（P〈0.05）.Ranking by P value,we found that p53 and MAPK pathways exhibited more significant up-regulation in the crypt than those in the villus.Representative genes of different DNA repair pathways were up-regulated to certain extent,which was coincident with the change of cell cycle.The characteristics of gene expression indicated high accurate homologous recombination,nonhomologous end joining,as well as nucleotide excision repair were the main DNA repair ways in crypt repair,however,rapid but error prone repair,mismatch repair was predominant in the villus for gene integrity maintenance.Conclusion IR-induced DNA damage response is related to cell differentiation status,and crypt cells are more sensitive to DNA damage.