The Role of FOS in Gene Regulation

The cellular protooncogene FOS is expressed at very low level in most cells of the organism and in most growing cells in culture. The synthesis is rapidly elevated if cells are exposed to one of a large number of agents and conditions. This suggests that FOS is an intermediate in the signal transfer of a variety of different specific genetic responses. Depriving cells of Fos protein indeed abolishes some of these responses: PDGF stimulated proliferation, transformation by several individual oncogenes, the serum, phorbol ester and UV induced expression of human collagenase and of HIV-1, the autoregulatory turn-off of FOS transcription. Fos protein exerts this key role by interacting with more than one transcription factor. Preliminary evidence suggests, that the specificity of pathways is maintained by the pathway-specific modulation of these transcription factors.