FUNCTIONS OF C-FOS PROTEIN IN CELLULAR PHYSIOLOGY

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The discovery that proto-oncogenes have the potential to produce cancer has created substantial interest in the functions of these normal cellular genes. c-fos protein is of particular importance because of its nuclear location, DNA binding capacity, and modulation of expression during cellular proliferation and differentiation. However, the function of the normal c-fos protein is unknown. The overall goal of this proposal is to elucidate specific functions for the c-fos protein. The proposed studies will employ genetic methods to create and analyze cellular mutants with altered c-fos expression, and cDNA cloning techniques to identify genes which are regulated by c-fos expression. The hypothesis to be tested is that c-fos protein is required for specific cellular processes because it alters the expression of genes with essential functions. The specific aims are: 1) To determine the Functional Domains of the normal c-fos protein which are necessary for fibroblast Proliferation; 2) To determine the Functional Domains of the normal c-fos protein which are necessary for Embryonal stem cell Proliferation and/or Differentiation; 3) To identify Genes which are regulated by c-fos expression. These studies are focused on the functional significance of both alterations in c-fos protein structure and induction of putative c-fos regulated genes. These proposed studies of normal nontransforming functional domains are feasible, based on preliminary data indicating that a mutant (anti-sense RNA resistant) fos gene restores proliferative function to anti-sense c-fos RNA inhibited fibroblasts. Experiments will analyze the functional significance of specific mutations in c-fos protein (e.g. alteration of putative phosphorylation sites, DNA binding regions, essential transforming domains) as a means to determine the role of this protein in such cellular processes as logarithmic proliferation, growth factor-induced DNA synthesis, wounding response, and differentiation. cDNA cloning techniques will be employed for identification of genes which are regulated by c-fos expression. The ultimate goal is to correlate the c-fos protein functional domains which are essential for altered expression of specific genes (AIM 3), with the domains which are required for proliferation and/or differentiation.