Polyomavirus tumorantigens have a profound effect on gene expression in mouse fibroblasts.
Polyomavirus (Py) large and small tumorantigens together are competent to induce S phase in growth-arrested mouse fibroblasts. The capacity of the large tumorantigen to bind the pocket proteins, pRB, p130 and p107, is important for the transactivation of DNA synthesis enzymes and the cyclins E and A, while the interference of small tumorantigen with protein phosphatase PP2A causes a destabilization of the cdk2 inhibitor p27, and thus leads to strong cyclin E- and cyclin A-dependent cdk2 activity. Py small tumorantigen, in addition, is able to transactivate cyclin A. Hence, this protein might have a much wider effect on gene expression in arrested mouse fibroblasts than hitherto suspected. This may have a profound part in the known capacity of Py to form tumors in mice. Therefore, it was interesting to gain an insight into the spectrum of transcriptional deregulation by Py tumorantigens. Accordingly, we performed microarray analysis of quiescent mouse fibroblasts in the absence and presence of small or large tumorantigen. We found that the viral proteins can induce or repress a great variety of genes beyond those involved in the S phase induction and DNA synthesis. The results of the microarray analysis were confirmed for selected genes by several methods, including real-time PCR. Interestingly, a mutation of the binding site for pocket proteins in case of LT and for PP2A in case of ST has a variable effect on the deregulation of genes by the viral proteins depending on the gene in question. In fact, some genes are transactivated by LT as well as ST completely independent of an interaction with their major cellular targets, pocket proteins and PP2A, respectively.
Klucky
Britta
B
Institute of Medical Biochemistry, Division of Molecular Biology, Medical University of Vienna, Dr. Bohrgasse 9, A-1030 Vienna, Austria.
Koch
Birgit
B
Radolf
Martin
M
Steinlein
Peter
P
Wintersberger
Erhard
E
D016475:3T3 Cells; D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D015820:Cadherins / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism; D019938:Cyclin D1 / Q000378:metabolism; D058575:Decorin; D016326:Extracellular Matrix Proteins; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D015870:Gene Expression; D051379:Mice; D064151:Minichromosome Maintenance Complex Component 6; D009218:Myosins / Q000378:metabolism; D016518:Neurofibromatosis 2 / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D011120:Polyomavirus / Q000276:immunology / Q000378:metabolism*; D011509:Proteoglycans / Q000037:antagonists & inhibitors; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000037:antagonists & inhibitors
D000952:Antigens, Polyomavirus Transforming; D015820:Cadherins; D018797:Cell Cycle Proteins; C546879:Dcn protein, mouse; D058575:Decorin; D016326:Extracellular Matrix Proteins; D011509:Proteoglycans; D016271:Proto-Oncogene Proteins c-myc; D043562:Receptors, G-Protein-Coupled; D025521:Tumor Suppressor Proteins; D019938:Cyclin D1; C086960:osteoblast cadherin; D009218:Myosins; C491205:Mcm6 protein, mouse; D064151:Minichromosome Maintenance Complex Component 6