Takagi Michihiro, Ohashi Kazuhiko, Morimura Toshifumi, Sugimoto Chihiro, Onuma Misao
Department of Microbiology and Immunology, Faculty of Agriculture, Kobe University, Kobe 657-8501, Japan.
Leuk Res. 2006 Aug;30(8):987-92. doi: 10.1016/j.leukres.2005.12.009. Epub 2006 Jan 31.
Several kinds of the p53 transcripts in which their open reading frames (ORFs) were truncated (ranging from 101 to 765 bp) were identified in Marek's disease (MD)-derived tumor cell lines as well as avian leukosis- and reticuloendotheliosis-derived ones, detected by nested RT-PCR and subsequent nucleotide sequence analysis. In these ORFs, regions encoding the proline-rich and DNA-binding domains of the p53 protein were frequently deleted, and many of these deletions were found to cause frame shift. Western blot analysis using anti-p53 monoclonal antibodies revealed that multiple p53 isoform proteins with various molecular weights including 45-46, 35 and 28 kDa were expressed in these tumor cell lines, though the p53 protein with a molecular weight of 49 kDa was detected in chicken embryo fibroblasts transformed by the SV40 T antigen as a control. Since no deletions were found in the p53 gene of these MD tumor cell lines, truncations in the p53 ORFs observed in this study might result from alternative splicing of the p53 gene.
通过巢式逆转录聚合酶链反应（RT-PCR）及后续核苷酸序列分析发现，在马立克氏病（MD）来源的肿瘤细胞系以及禽白血病和网状内皮组织增生症来源的肿瘤细胞系中，鉴定出了几种p53转录本，其开放阅读框（ORF）被截断（范围从101至765碱基对）。在这些开放阅读框中，编码p53蛋白富含脯氨酸结构域和DNA结合结构域的区域经常缺失，并且发现许多此类缺失会导致移码。使用抗p53单克隆抗体的蛋白质免疫印迹分析表明，在这些肿瘤细胞系中表达了多种不同分子量的p53异构体蛋白，包括45 - 46、35和28千道尔顿，而作为对照，在经SV40 T抗原转化的鸡胚成纤维细胞中检测到了分子量为49千道尔顿的p53蛋白。由于在这些MD肿瘤细胞系的p53基因中未发现缺失，本研究中观察到的p53开放阅读框截断可能是p53基因可变剪接的结果。
