c-fos mediated stimulation of an AP-1 DNA binding activity in undifferentiated teratocarcinoma cell lines.
Undifferentiated F9 and PCC4 embryonal carcinoma (EC) cells contain low levels of AP-1 DNA binding activity. Upon differentiation induced by retinoic acid and cyclic AMP or in differentiated cell lines, AP-1 DNA binding activity can be readily detected. Minute amounts of 3T6 cells extracts, that by themselves were unable to show any binding to an AP-1 site, stimulate AP-1 DNA binding activity when added to the EC cell extracts, suggesting that components of the 3T6 extracts stimulate this DNA binding activity in F9 and PCC4 cell extracts. This enhancement of DNA binding activity requires the presence in the donor fraction (3T6 cells) of a thermostable protein(s) that possesses neither protein kinase nor phosphatase activities. The proteins responsible for stimulation in 3T6 extracts can be separated from the ones responsible for AP-1 binding by chromatography. 3T6 c-fos immunodepleted fractions are unable to activate AP-1 DNA binding activity in EC cell extracts, while c-jun depleted fractions activate normally. Moreover, in vitro translated c-fos, but not c-jun proteins, are able to stimulate binding in EC extracts. These data suggest an important role for c-fos protein in activation of a specific DNA binding transcriptional factor during cellular differentiation and provide a convenient in vitro assay for c-fos function.
Caceres
J
J
Wistar Institute of Anatomy and Biology, Philadelphia, Pennsylvania 19104.
Glikin
G
G
Bravo
R
R
Weinmann
R
R
D002454:Cell Differentiation; D004247:DNA / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000032:analysis / Q000378:metabolism*; D054278:Embryonal Carcinoma Stem Cells; D006801:Humans; D014411:Neoplastic Stem Cells / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000502:physiology; D014176:Protein Biosynthesis; D011494:Protein Kinases / Q000502:physiology; D011518:Proto-Oncogene Proteins / Q000032:analysis / Q000502:physiology*; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D013724:Teratoma / Q000378:metabolism* / Q000473:pathology; D014157:Transcription Factors / Q000032:analysis / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D014157:Transcription Factors; D004247:DNA; D011494:Protein Kinases; D010744:Phosphoric Monoester Hydrolases