Résumé
c-fos is a well-known proto-oncogene and an immediate-early gene whose role is still debated. Its transcriptional activation is very quick and transient, which requires a tight regulation.<br />c-fos transcriptional control by intragenic sequences was studied through two different aspects. First, a transcriptional block in the first intron was shown to occur in cultured Ltk- fibroblasts, as shown before in macrophages. This block was relieved by increasing calcium intracellular concentration, and we demonstrated that this did not require CaM-Kinases nor calcineurin, but was linked to a new calmodulin-dependent pathway that remains to be characterised.<br />In the second part of my thesis work, we identified dowstream the blockade region a new, very conserved intronic sequence which has many features of a promoter. This alternate promoter was shown to be active in transient transfection. We thus constructed transgenic mice carrying a b-galactosidase reporter under the control of this putative intronic promoter. Thanks to these mice we could detect the activity of this promoter during development restricted to neural structures and developing mammary gland.<br />We thus studied two very close new regions involved in c-fos transcriptional regulation at two different levels, and speculate that these activities are coordinated.