Artificial oncoproteins: modified versions of the yeast bZip protein GCN4 induce cellular transformation.
We have constructed artificial AP-1 proteins containing elements derived from yeast GCN4 and from the herpes simplex virus activator VP16. These proteins can only homodimerize but do not heterodimerize, and lacking significant homology to Jun outside the DNA-binding domain, they are largely unaffected by proteins that modulate Jun. Constructs in which the transactivation domain of GCN4 is replaced by that of VP16 induce oncogenic transformation in cultures of chicken embryo fibroblasts. The availability of transforming VP16-GCN4 fusion proteins permits an evaluation of downstream target genes, based on the hypothesis that transformation-relevant targets should be common between Jun and the artificial AP-1 proteins. In a pilot study, we examined the expression of several Jun target genes in cells transformed by the VP16-GCN4 fusions and found that some of the Jun targets are not upregulated by the GCN4-derived transforming construct, suggesting that their upregulation in Jun-transformed cells is not essential for cell transformation. We have further constructed a regulatable GCN4-VP16 protein that will permit a kinetic characterization of target gene responses and will facilitate discrimination between direct and indirect targets.
Nishizawa
Makoto
M
Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA.
Fu
Shu-Ling
SL
Kataoka
Kohsuke
K
Vogt
Peter K
PK
D000818:Animals; D050976:Basic-Leucine Zipper Transcription Factors; D002455:Cell Division / Q000235:genetics; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D002478:Cells, Cultured; D002642:Chick Embryo; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D051790:G-Box Binding Factors; D015972:Gene Expression Regulation, Neoplastic; D017930:Genes, Reporter; D017405:Herpes Simplex Virus Protein Vmw65 / Q000235:genetics / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D015513:Oncogene Proteins / Q000235:genetics* / Q000378:metabolism*; D010865:Pilot Projects; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation; D014162:Transfection
D050976:Basic-Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; D051790:G-Box Binding Factors; D017405:Herpes Simplex Virus Protein Vmw65; D015513:Oncogene Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D008156:Luciferases; D011494:Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases