Nishida M, Miyamoto S, Kato H, Miwa T, Imamura T, Miwa K, Yasumoto S, Barrett J C, Wake N
Department of Reproductive Physiology and Endocrinology, Kyushu University, Beppu, Japan.
Mol Carcinog. 1995 Jul;13(3):157-65. doi: 10.1002/mc.2940130305.
To explore the role of the E7 viral oncogene from human papillomavirus type 16 (HPV 16) in the regulation of cytoskeletal organization, we investigated alterations in particular cytoskeletal components in rat embryonal fibroblasts and three transformants of rat embryonal fibroblast cells produced by transfections with HPV16 E7 alone (TF1), HPV16 E7 plus adenovirus type 5 E1B (TF3), and HPV16 E7 plus activated Ha-ras (TF4). Marked reductions in smooth-muscle (SM) alpha-actin content and disrupted organization of stress fibers detected by anti-SM alpha-actin antibody were evident in all the transformants. These cytoskeletal manifestations were associated with a significant reduction in the mRNAs in these cells. Transcriptional repression by the E7 gene was observed after transient transfection of a chloramphenicol acetyltransferase reporter gene with SM alpha-actin gene promoter. Nucleotides -123 to -39 of the SM alpha-actin gene promoter were required for the HPV16 E7 transcriptional repression as shown by the chloramphenicol acetyltransferase assay. The downregulation of this actin isoform mediated by the E7 oncoprotein may play an important role in cell transformation by HPV16.
为了探究人乳头瘤病毒16型（HPV 16）的E7病毒癌基因在细胞骨架组织调节中的作用，我们研究了大鼠胚胎成纤维细胞以及通过单独转染HPV16 E7（TF1）、HPV16 E7加5型腺病毒E1B（TF3）和HPV16 E7加活化的Ha-ras（TF4）产生的三种大鼠胚胎成纤维细胞转化体中特定细胞骨架成分的变化。在所有转化体中，抗平滑肌（SM）α-肌动蛋白抗体检测到的平滑肌（SM）α-肌动蛋白含量显著降低以及应力纤维组织紊乱明显可见。这些细胞骨架表现与这些细胞中mRNA的显著减少相关。在用SMα-肌动蛋白基因启动子瞬时转染氯霉素乙酰转移酶报告基因后，观察到E7基因的转录抑制。氯霉素乙酰转移酶分析表明，HPV16 E7转录抑制需要SMα-肌动蛋白基因启动子的-123至-39核苷酸。由E7癌蛋白介导的这种肌动蛋白同工型的下调可能在HPV16的细胞转化中起重要作用。
