Simian virus 40 large tumor antigen modulates the Raf signaling pathway.
The large tumor antigen of simian virus 40 (SVLT) is a potent oncogene. Although inactivation of the p53 and pRb tumor suppressors has been causally linked to the transforming properties of SVLT, its exact mechanism of action remains undefined. Previous data indicated that Ras is activated in SVLT-expressing cells. In this report we show that SVLT also increases Raf kinase activity in both insect and mammalian cells, thus identifying the Raf kinase as an additional target of SVLT. Our results further show that SVLT was still able to activate Raf in cells where Ras levels had been drastically reduced through expression of an antisense construct, indicating that SVLT may activate Raf at least partly by a mechanism that is independent of its stimulatory effect on Ras.
Grammatikakis
N
N
Department of Physiology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
Jaronczyk
K
K
Siganou
A
A
Vultur
A
A
Brownell
H L
HL
Benzaquen
M
M
Rausch
C
C
Lapointe
R
R
Gjoerup
O
O
Roberts
T M
TM
Raptis
L
L
D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000378:metabolism / Q000502:physiology*; D020134:Catalytic Domain; D002460:Cell Line; D015536:Down-Regulation; D004789:Enzyme Activation; D005347:Fibroblasts / Q000378:metabolism; D011905:Genes, ras / Q000235:genetics; D006801:Humans; D007313:Insecta; D051379:Mice; D010641:Phenotype; D010766:Phosphorylation; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism*; D015398:Signal Transduction; D014162:Transfection; D018631:ras Proteins / Q000378:metabolism
D000952:Antigens, Polyomavirus Transforming; D019908:Proto-Oncogene Proteins c-raf; D018631:ras Proteins