共查询到20条相似文献,搜索用时 453 毫秒
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A c-Ha-ras oncogene, to a lesser extent the c-Ha-ras proto-oncogene, and the tumor promoter 12-O-tetradecanoylphorbol-13-acetate activate the inactive polyoma virus (Py) enhancer in a myeloma cell line and the partially active Py enhancer in NIH 3T3 fibroblasts, but have no effect on the active Py enhancer in LMTK- fibroblasts. In addition, c-Ha-ras can stimulate the inactive Py enhancer in embryonal carcinoma F9 cells. c-Ha-ras activation in embryonal carcinoma cells does not appear to involve reversal of "E1A-like" inhibition of the enhancer. We suggest that modulation of cellular enhancer activity could play a key role in tumorigenesis by oncogenes. 相似文献
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The PEA3 subfamily of Ets transcription factors synergizes with beta-catenin-LEF-1 to activate matrilysin transcription in intestinal tumors 总被引:10,自引:0,他引:10 下载免费PDF全文
Crawford HC Fingleton B Gustavson MD Kurpios N Wagenaar RA Hassell JA Matrisian LM 《Molecular and cellular biology》2001,21(4):1370-1383
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A polyoma mutant that encodes small T antigen but not middle T antigen demonstrates uncoupling of cell surface and cytoskeletal changes associated with cell transformation. 总被引:26,自引:5,他引:21 下载免费PDF全文
The hr-t gene of polyoma virus encodes both the small and middle T (tumor) antigens and exerts pleiotropic effects on cells. By mutating the 3' splice site for middle T mRNA, we have constructed a virus mutant, Py808A, which fails to express middle T but encodes normal small and large T proteins. The mutant failed to induce morphological transformation or growth in soft agar, but did stimulate postconfluent growth of normal cells. Cells infected by Py808A became fully agglutinable by lectins while retaining normal actin cable architecture and normal levels of extracellular fibronectin. These properties of Py808A demonstrated the separability of structural changes at the cell surface from those in the cytoskeleton and extracellular matrix, parameters which have heretofore been linked in the action of the hr-t and other viral oncogenes. 相似文献
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Two different factors bind to the alpha-domain of the polyoma virus enhancer, one of which also interacts with the SV40 and c-fos enhancers. 总被引:67,自引:8,他引:59 下载免费PDF全文
Two nuclear factors from mouse 3T6 cells bind to a 22-bp segment constituting the alpha-domain of the polyoma virus enhancer. Binding of each factor can be competed out selectively by the appropriate double-stranded oligonucleotide, indicating that this binding is not strictly cooperative. Sequence homology between the two binding sites and the similar size of the protected regions may indicate that both factors, PEA1 and PEA2, are closely related. The binding site of PEA1 is centered on a sequence showing strong homology to the SV40 enhancer, the binding site of PEA2 is located immediately adjacent to it and shows a strong homology to the c-fos enhancer. Surprisingly, both SV40 and c-fos enhancers interact with PEA1, probably due to the presence of an extra base pair relative to c-fos in the PEA2 site. Factor PEA1 is probably identical to the recently described activator protein 1 (AP1). 相似文献
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