REGULATION OF C-FOS PROTOONCOGENE

The c-fos protooncogene is rapidly and transiently activated by divers e stimuli. Thus, it is controlled by several signal transduction syste ms. The complex structure of the c-fos promotor contributes to the cor responding functional properties of this gene related to cell differen tiation and proliferation and a number of stress reactions. Binding of external factors to the cell surface specifically activates intracell ular processes leading to the interaction of specific transcription fa ctors with the c-fos promotor. Depending on the characteristics of thi s interaction, various signal transduction pathways can be activated; key roles in these reactions are played by membrane components (recept ors, G-proteins, Ras, adaptor proteins, tyrosine-specific protein kina ses) and cytoplasmic protein kinases (PKC, PKA, components of MAP-kina se cascade). Most of the signal transduction pathways are straightforw ard, but some of their components interact with additional factors, th us complicating the signal transduction network and providing for exte nded possibilities of c-fos regulation.