title: Nerve growth factor, but not epidermal growth factor, increases Fra-2 expression and alters Fra-2/JunD binding to AP-1 and CREB binding elements in pheochromocytoma (PC12) cells.
abstract: In pheochromocytoma (PC12) cells nerve growth factor (NGF) and epidermal growth factor (EGF) activate similar receptor tyrosine kinase signaling pathways but evoke strikingly different biological outcomes: NGF induces differentiation and EGF acts as a mitogen. A novel approach was developed for identifying transcription factor activities associated with NGF-activated, but not EGF-activated, signaling, using random oligonucleotide clones from a DNA recognition library to isolate specific DNA binding proteins from PC12 nuclear extracts. A protein complex from NGF-treated, but not EGF-treated, cells was identified that exhibits increased mobility and DNA binding activity in gel mobility shift assays. The binding complex was identified in supershift assays as Fra-2/JunD. The clones used as probes contain either AP-1 or cAMP response element binding (CREB) recognition elements. Time course experiments revealed further differences in NGF and EGF signaling in PC12 cells. NGF elicits a more delayed and sustained ERK phosphorylation than EGF, consistent with previous reports. Both growth factors transiently induce c-fos, but NGF evokes a greater response than EGF. NGF specifically increases Fra-1 and Fra-2 levels at 4 and 24 hr. The latter is represented in Western blots by bands in the 40-46 kDa range. NGF, but not EGF, enhances the upper bands, corresponding to phosphorylated Fra-2. These findings suggest that prolonged alterations in Fra-2 and subsequent increases in Fra-2/JunD binding to AP-1 and CREB response elements common among many gene promoters could serve to trigger broadly an NGF-specific program of gene expression.
authors.affiliation: Departments of Pharmacology and Pathology, Emory University School of Medicine, Atlanta, Georgia 30329, USA.
authors.forename: V
authors.initials: V
authors.lastname: Boss
authors.forename: J D
authors.initials: JD
authors.lastname: Roback
authors.forename: A N
authors.initials: AN
authors.lastname: Young
authors.forename: L J
authors.initials: LJ
authors.lastname: Roback
authors.forename: D M
authors.initials: DM
authors.lastname: Weisenhorn
authors.forename: R
authors.initials: R
authors.lastname: Medina-Flores
authors.forename: B H
authors.initials: BH
authors.lastname: Wainer
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002454:Cell Differentiation / Q000187:drug effects; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D004815:Epidermal Growth Factor / Q000378:metabolism* / Q000494:pharmacology; D051921:Fos-Related Antigen-2; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D020932:Nerve Growth Factor / Q000378:metabolism* / Q000494:pharmacology; D016716:PC12 Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism*; D051381:Rats; D012045:Regulatory Sequences, Nucleic Acid / Q000187:drug effects / Q000235:genetics*; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014157:Transcription Factors / Q000096:biosynthesis*
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; D051921:Fos-Related Antigen-2; C497874:Fosl2 protein, rat; D016755:Proto-Oncogene Proteins c-jun; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D004815:Epidermal Growth Factor; D020932:Nerve Growth Factor; D020928:Mitogen-Activated Protein Kinases