Cell cycle progression in monkey cells expressing simian virus 40 small t antigen from adenovirus vectors.
The simian virus 40 small t antigen (small-t) is required for optimal viral replication and transformation, especially during the infection of nondividing cells, suggesting that the function of small-t is to promote cell cycle progression. The mechanism through which small-t promotes cell growth reflects, in part, its binding and inhibition of protein phosphatase 2A (PP2A). The use of recombinant adenoviruses allows small-t expression in a majority of cells in a population, thus providing a convenient source of cells for biochemical analyses. In monkey kidney CV1 cells, small-t expressed from these adenovirus vectors activated the mitogen-activated protein kinase (MAPK) pathway, induced JNK activity, and increased AP-1 DNA-binding activity, all in a PP2A-dependent manner. Expression of small-t also caused an increase in the phosphorylation of the Na+/H+ antiporter, a mitogen-activated ion exchanger whose activity correlates with its phosphorylation. At least part of the antiporter phosphorylation induced by small-t reflected activation of the MAPK pathway, as suggested by results of assays using a chemical inhibitor of the MAPK-activating kinase, MEK. Finally, small-t expression from adenovirus vectors promoted efficient cell cycle progression by growth-arrested cells. These vectors should facilitate further analysis of effects of small-t on cell cycle mediators.
Howe
A K
AK
Department of Microbiology-Immunology and The Lurie Cancer Center, Northwestern University, Chicago, Illinois 60611, USA.
Gaillard
S
S
Bennett
J S
JS
Rundell
K
K
D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D000957:Antigens, Viral, Tumor / Q000235:genetics*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002453:Cell Cycle; D002455:Cell Division; D002460:Cell Line; D002522:Chlorocebus aethiops; D004789:Enzyme Activation; D005822:Genetic Vectors; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D048728:MAP Kinase Kinase Kinase 1; D020928:Mitogen-Activated Protein Kinases; D009154:Mutation; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D010766:Phosphorylation; D054648:Protein Phosphatase 2; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D013539:Simian virus 40 / Q000235:genetics* / Q000276:immunology* / Q000502:physiology; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014779:Virus Replication
D000957:Antigens, Viral, Tumor; D017923:Sodium-Hydrogen Exchangers; D018808:Transcription Factor AP-1; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048728:MAP Kinase Kinase Kinase 1; C482576:MAP3K1 protein, human; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2