Transcriptional activation of the CEF-4/9E3 cytokine gene by pp60v-src.
The CEF-4/9E3 gene is expressed constitutively in Rous sarcoma virus (RSV)-transformed cells. This expression is largely determined by an increase in transcription of the gene. In this report, we characterize the regulatory elements responsible for the transformation-dependent activation of CEF-4/9E3. Three sequences corresponding to AP-1, PRD II/kappa B, and TAACGCAATT are involved in the process and therefore define the src-responsive unit (SRU) of the CEF-4 promoter. In constructs containing a deletion of the SRU, multiple copies of AP-1 or PRD II/kappa B, but not TAACGCAATT, led to activation of the promoter. Thus, factors interacting with these elements are constitutively activated in RSV-transformed chicken embryo fibroblasts. In agreement with the results of transient expression assays, protein binding to AP-1, PRD II/kappa B, and TAACGCAATT were more abundant in the nuclei of transformed cells. The expression of the CEF-4 promoter was investigated in cells infected by a temperature-sensitive mutant of RSV. No significant increase in CEF-4 promoter activity was detected early after activation of pp60v-src. In contrast, a substantial activation of the CEF-4 promoter was detected late after a temperature shift. Factors interacting with the TAACGCAATT, PRD II/kappa B, and AP-1 elements accumulated gradually over a period of several hours. Therefore, transcriptional activation plays an important role in the late, constitutive expression of the CEF-4 gene in stably transformed cells.
Dehbi
M
M
Département de Biochimie, Université de Montréal, Québec, Canada.
Mbiguino
A
A
Beauchemin
M
M
Chatelain
G
G
Bédard
P A
PA
D000818:Animals; D030161:Avian Proteins; D001483:Base Sequence; D002472:Cell Transformation, Viral; D002478:Cells, Cultured; D002642:Chick Embryo; D016207:Cytokines / Q000235:genetics*; D004268:DNA-Binding Proteins; D005347:Fibroblasts; D005786:Gene Expression Regulation; D016391:Genes, src; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics*; D014158:Transcription, Genetic; D014170:Transformation, Genetic
D030161:Avian Proteins; D016207:Cytokines; D004268:DNA-Binding Proteins; C071280:EMF-1 protein, Gallus gallus