Oncogene and Tumor Suppressor Gene Products Regulating c-fos Expression
The genetic response of cells to Extracellular molecules often requires signal receptors, signal transduction to the nucleus, and usually alterations in transcription factor activity, which activates or represses the respective target genes. This chapter focuses on known (proto-)oncogene and tumor suppressor gene products that regulate c-fos gene expression, and describes promoter elements that are responsive to their activity. The discovery of the platelet-derived growth factor-2 gene as the cellular counterpart of the v-sis oncogene of simian sarcoma virus provided early evidence of oncoprotein-regulated gene expression. The level of chloramphenicol-acetyltransferase expression reflects the activity of the transfected c-fos promoter in the presence of the cotransfected oncogene. The retinoblastoma control element, is regulated by the product of the retinoblastoma tumor suppressor gene. The chapter describes negative regulation of c-fos expression by the protein products of tumor suppressor genes. Most studies of c-fos promoter activity in response to certain stimuli analyze isolated fragments of the promoter.