title: Epidermal-growth-factor-induced proliferation of astrocytes requires Egr transcription factors.
abstract: Stimulation of astrocytes with epidermal growth factor (EGF) induced proliferation and triggered the biosynthesis of the transcription factor Egr-1, involving the activation of the extracellular signal-regulated protein kinase (ERK) signaling pathway. No differences in the proliferation rate of astrocytes prepared from wild-type or Egr-1-deficient mice were detected. However, expression of a dominant-negative mutant of Egr-1 that interfered with DNA-binding of all Egr proteins prevented EGF-induced proliferation of astrocytes. Site-directed mutagenesis of two crucial cysteine residues within the zinc finger DNA-binding domain revealed that DNA-binding of the Egr-1 mutant was essential to inhibit proliferation of EGF-stimulated astrocytes. Expression of NAB2 (a negative co-regulator of Egr-1, Egr-2 and Egr-3) or a dominant-negative mutant of Elk-1 (a key regulator of Egr-1 biosynthesis) abolished EGF-induced proliferation of astrocytes. Chromatin immunoprecipitation experiments showed that Egr-1, Egr-2 and Egr-3 bound to the gene expressing basic fibroblast growth factor (bFGF) in EGF-stimulated astrocytes. Egr-2 and Egr-3 also interacted with the bFGF gene in EGF-stimulated astrocytes prepared from Egr-1-deficient mice, indicating that loss of Egr-1 is compensated by other Egr proteins. Together, these data show that Egr transcription factors are essential for conversion of the mitogenic signal of EGF into a proliferative response.
authors.affiliation: Department of Medical Biochemistry and Molecular Biology, University of Saarland Medical Center, D-66421 Homburg, Germany.
authors.forename: Sabine I
authors.initials: SI
authors.lastname: Mayer
authors.forename: Oliver G
authors.initials: OG
authors.lastname: Rössler
authors.forename: Takeshi
authors.initials: T
authors.lastname: Endo
authors.forename: Patrick
authors.initials: P
authors.lastname: Charnay
authors.forename: Gerald
authors.initials: G
authors.lastname: Thiel
mesh_terms: D051698:Activating Transcription Factor 2 / Q000378:metabolism; D000818:Animals; D001253:Astrocytes / Q000166:cytology* / Q000187:drug effects* / Q000201:enzymology; D049109:Cell Proliferation / Q000187:drug effects; D002843:Chromatin / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D051766:Early Growth Response Protein 1 / Q000172:deficiency / Q000378:metabolism; D051765:Early Growth Response Transcription Factors / Q000096:biosynthesis / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D016222:Fibroblast Growth Factor 2 / Q000235:genetics / Q000378:metabolism; D005799:Genes, Dominant; D017930:Genes, Reporter; D008156:Luciferases / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects; D051379:Mice; D008934:Mitogens / Q000494:pharmacology; D050505:Mutant Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D009363:Neoplasm Proteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D050807:ets-Domain Protein Elk-1 / Q000378:metabolism
chemical_list: D051698:Activating Transcription Factor 2; D002843:Chromatin; D051766:Early Growth Response Protein 1; D051765:Early Growth Response Transcription Factors; C486109:Egr1 protein, mouse; D008934:Mitogens; D050505:Mutant Proteins; C099945:Nab2 protein, mouse; D009363:Neoplasm Proteins; D012097:Repressor Proteins; D050807:ets-Domain Protein Elk-1; D016222:Fibroblast Growth Factor 2; D004815:Epidermal Growth Factor; D004247:DNA; D008156:Luciferases; D019908:Proto-Oncogene Proteins c-raf; D048049:Extracellular Signal-Regulated MAP Kinases