Increased cyclin A and decreased cyclin D levels in adenovirus 5 E1A-transformed rodent cell lines.
Adenovirus-(Ad)- E1A proteins carry two conserved domains (CR1 and CR2) required for transformation of primary rodent cells and essential for association with cellular proteins, including p105RB, p58cyclin A and p33cdk2. We show that in normal rat kidney 49F (NRK) cell lines expressing various mutant Ad5-E1A genes, CR2-, but not CR-1-, deletion mutants induce a typical transformed phenotype as characterized by morphology, absence of density arrest and loss of serum requirement. This indicates that induction of these transformed properties is a function of CR1. The fact that E1A proteins with deletions in CR2 show a greatly reduced association with RB, cyclin A and p33cdk2 suggests that these associations are dispensable for E1A-mediated transformation of NRK cells. Induction of the transformed properties is accompanied by a CR1-dependent increase in Proliferating Cell Nuclear Antigen and cyclin A gene expression. Elevated mRNA and protein levels of cyclin A were also found in Ad12-E1-transformed NRK cells but not in ras-transformed NRK cells. On the other hand, cyclin D expression is decreased in a CR1-dependent manner. Although Ad5-E1A proteins are sufficient to transform NRK cells, further deregulation of growth is obtained when Ad5-E1B proteins are co-expressed. One of the Ad5-E1B effects is the sequestration of the p53 protein into a cytoplasmic body containing the p53/Ad5-E1B-55 kD complex. Interestingly, in NRK cell lines expressing Ad5-E1B-55 kD, cyclin A could be detected not only in the nucleus but also in the cytoplasmic bodies. These results indicate that the deregulation of cell cycle control by the Adenovirus-E1 region may be due to a CR1-dependent alteration of the expression of cyclins A and D.
Inserm U55, Centre de Recherches Paris Saint-Antoine, France.
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T
Buchou
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Kranenburg
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H
van Dam
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Roelen
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Zantema
F L
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Hall
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van der Eb
D017500:Adenovirus E1A Proteins / Q000737:chemistry / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D002461:Cell Line, Transformed; D002471:Cell Transformation, Neoplastic / Q000378:metabolism*; D016213:Cyclins / Q000032:analysis*; D008969:Molecular Sequence Data; D009154:Mutation; D051381:Rats; D013329:Structure-Activity Relationship
D017500:Adenovirus E1A Proteins; D016213:Cyclins