Jung M, Lee S A, Zhang Y, Dritschilo A
Department of Radiation Medicine, Vincent T. Lombardi Cancer Center, Georgetown University Medical Center, Washington, DC 20007-2197, USA.
Int J Radiat Oncol Biol Phys. 1997 Jan 15;37(2):417-22. doi: 10.1016/s0360-3016(96)00500-7.
An analysis of the structure and expression of p53 in fibroblasts from patients with ataxia telangiectasia (AT) is presented.
p53 status in primary and SV40 T antigen-transformed AT cell lines was analyzed using immunocytochemistry and by sequencing with the dideoxynucleotide termination method. The expression of p53 transcript was measured by Northern analysis. The kinetics of p53 protein expression and DNA-binding activity were measured at various intervals following irradiation.
No mutation of p53 sequences was found in AT cells. Decreased levels of p53 mRNA and protein were observed in AT5BIVA cells compared to other SV40 T antigen-immortalized fibroblasts. Furthermore, DNA-protein binding analysis shows that a fraction of p53 in the nuclear extracts from AT5BIVA is regulated and binds to specific DNA sequence following irradiation.
These data provide evidence for a heterogeneity of the p53 function in SV40-transformed AT cells. It also supports the hypothesis that a regulatory mechanism of p53 activity remains in T antigen-expressing cells in response to ionizing radiation damage.
对共济失调毛细血管扩张症（AT）患者成纤维细胞中p53的结构和表达进行分析。
采用免疫细胞化学和双脱氧核苷酸末端终止法测序，分析原代及SV40 T抗原转化的AT细胞系中的p53状态。通过Northern分析测定p53转录本的表达。在照射后的不同时间间隔测量p53蛋白表达动力学和DNA结合活性。
在AT细胞中未发现p53序列突变。与其他SV40 T抗原永生化成纤维细胞相比，在AT5BIVA细胞中观察到p53 mRNA和蛋白水平降低。此外，DNA-蛋白质结合分析表明，照射后AT5BIVA细胞核提取物中的一部分p53受到调控并与特定DNA序列结合。
这些数据为SV40转化的AT细胞中p53功能的异质性提供了证据。它也支持这样一种假设，即p53活性的调节机制在表达T抗原的细胞中仍然存在，以应对电离辐射损伤。
