Antisense rescue defines specialized and generalized functional domains for c-Fos protein.
Serum induces the expression of a number of proteins with similar transcriptional properties, including those encoded by the proto-oncogenes c-fos and c-jun. This study employs a novel antisense rescue method to determine whether antisense-resistant genes (constructed by deletion of antisense RNA target sequences) can replace c-fos expression during serum-induced DNA synthesis. Immunoprecipitation studies and nuclease protection assays demonstrated that anti-fos RNA inhibited endogenous c-fos expression but did not inhibit expression of transfected antisense-resistant mutant c-fos genes. The results of nuclear-labelling and cellular-proliferation studies indicated that C terminally truncated Fos mutants, including FBR v-fos, could not rescue endogenous Fos, although full-length and minimally truncated c-fos expression vectors could restore serum-induced DNA synthesis in cells expressing anti-fos RNA. Overexpression of c-Jun protein (Jun) could not restore serum-induced DNA synthesis to cells expressing inducible anti-fos RNA despite equivalent transactivation of an AP-1 target gene. Thus, the antisense rescue method defines a specialized function for c-Fos protein which is distinct from the function(s) of Jun and/or transforming FBR v-Fos proteins.
Department of Cell Biology, Vanderbilt University, Medical School, Nashville, Tennessee 37232.
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Holt
D016475:3T3 Cells; D000818:Animals; D001483:Base Sequence; D016895:Culture Media, Serum-Free; D004261:DNA Replication; D016762:Genes, fos; D016758:Genes, jun / Q000187:drug effects*; D005822:Genetic Vectors; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D016376:Oligonucleotides, Antisense / Q000494:pharmacology*; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism*; D016755:Proto-Oncogene Proteins c-jun / Q000096:biosynthesis / Q000235:genetics; D016372:RNA, Antisense / Q000235:genetics; D012091:Repetitive Sequences, Nucleic Acid; D015183:Restriction Mapping; D014162:Transfection
D016895:Culture Media, Serum-Free; D016376:Oligonucleotides, Antisense; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D016372:RNA, Antisense