V-sis gene (SSV) is expressed transiently and independently of v-gag (SSAV) after infection of fibroblasts with SSV/SSAV.
To investigate the mechanism of cell transformation by the retroviral v-sis gene, we examined the mode of its mRNA expression after infection of primate fibroblasts with Simian Sarcoma Virus (SSV/SSAV). Surprisingly transient expression of the 5.3 kb transcript of v-sis was detected between day two and four after infection. Addition of cycloheximide did not reverse the down-regulation of v-sis expression. Suramin, which uncouples the PDGF receptor complex, had no effect on the pattern of v-sis expression. A marginal but non-transient expression of c-myc and c-fos mRNA upon v-sis expression was detected. Studies on nuclear run-off and m-RNA stability suggest that the half-life time of v-sis mRNA is about 8 h or longer and that its expression is controlled rather by transcriptional than by post-transcriptional mechanisms. The up and down regulation of v-sis expression is independent of the expression of the helper virus (SSAV) gag-genes. This indicates that v-sis oncogene (SSV) and structural genes of the helper virus (SSAV) are obviously under separate expression control.
Schätzl
H M
HM
Max von Pettenkofer Institute for Hygiene and Medical Microbiology, University of Munich, Federal Republic of Germany.
von der Helm
K
K
D000818:Animals; D002143:Callitrichinae; D002471:Cell Transformation, Neoplastic; D003513:Cycloheximide / Q000494:pharmacology; D005786:Gene Expression Regulation; D015683:Gene Products, gag; D005796:Genes; D006378:Helper Viruses / Q000235:genetics; D020575:Oncogene Proteins v-sis; D009857:Oncogenes; D011518:Proto-Oncogene Proteins / Q000235:genetics; D016760:Proto-Oncogene Proteins c-fos; D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger / Q000032:analysis; D011956:Receptors, Cell Surface / Q000378:metabolism; D017479:Receptors, Platelet-Derived Growth Factor; D012191:Retroviridae Proteins / Q000235:genetics*
D015683:Gene Products, gag; D020575:Oncogene Proteins v-sis; D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D012191:Retroviridae Proteins; D003513:Cycloheximide; D017479:Receptors, Platelet-Derived Growth Factor