Institute of Combined Injury, State Key Laboratory of Trauma, Burns and Combined Injury, Department of Radiation Medicine, School of Preventive Medicine, The Third Military Medical University, 30 Gaotanyan Street, Shapingba District, Chongqing 400038, China.
Department of Chemical Defense, School of Preventive Medicine, The Third Military Medical University, 30 Gaotanyan Street, Shapingba District, Chongqing 400038, China.
Arch Biochem Biophys. 2014 Jan 15;542:21-7. doi: 10.1016/j.abb.2013.11.012. Epub 2013 Dec 4.
Cells respond differently to DNA damaging agents, which may related to cell context and differentiation status. The aim of present study was to observe the cellular and molecular responses of cells in different differentiation status to ionizing irradiation (IR).
Crypt-villus unit of murine small intestine was adopted as a cell differentiation model. DNA damage responses (DDRs) of crypt and villus were observed 1-24 h after 12 Gy IR using gene expression microarray analysis, immunohistochemical staining, Western blotting and Electrophoretic Mobility Shift Assay.
Microarray analysis revealed that most differentially expressed genes were related to p53 signaling pathway in crypt 4h after IR and in both crypt and villus 24h after IR. In crypt stem cells/progenitor cells, H2AX was phosphorylated and dephosphorylated quickly, Ki67 attenuated, cell apoptosis enhanced, phosphorylated P53 increased and translocated into nuclear with the ability to bind p53-specific sequence. In upper crypt (transit amplifying cells) and crypt-villus junction, cells kept survive and proliferate as indicated by retained Ki67 expression, suppressed p53 activation, and rare apoptosis.
DDRs varied with cell differentiation status and cell function in small intestinal epithelium. P53 signaling pathway could be an important regulatory mechanism of DDRs.
细胞对 DNA 损伤剂的反应不同，这可能与细胞环境和分化状态有关。本研究旨在观察不同分化状态下的细胞对电离辐射（IR）的细胞和分子反应。
采用鼠小肠隐窝-绒毛单位作为细胞分化模型。用基因表达微阵列分析、免疫组织化学染色、Western blot 和电泳迁移率变动分析，观察 12 Gy IR 后 1-24 h 隐窝和绒毛的 DNA 损伤反应（DDRs）。
微阵列分析显示，IR 后 4 h 隐窝和 24 h 隐窝和绒毛中大多数差异表达基因与 p53 信号通路有关。在隐窝干细胞/祖细胞中，H2AX 迅速磷酸化和去磷酸化，Ki67 减弱，细胞凋亡增强，磷酸化 P53 增加并转位入核，与 p53 特异性序列结合。在上隐窝（过渡扩增细胞）和隐窝-绒毛交界处，细胞保持存活和增殖，表现为 Ki67 表达持续、p53 激活受抑制和凋亡罕见。
DDRs 随小肠上皮细胞的分化状态和细胞功能而变化。p53 信号通路可能是 DDRs 的重要调节机制。
