Ras-Mediated Phosphorylation of a Conserved Threonine Residue Enhances the Transactivation Activities of c-Ets1 and c-Ets2
| Autor: | David A. Hume, Beom-Seok Yang, Michael C. Ostrowski, G. Henkel, Katryn J. Stacey, C. A. Hauser, M. S. Colman, R. A. Maki, C. Van Beveren |
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| Rok vydání: | 1996 |
| Předmět: |
Threonine
Transcriptional Activation Molecular Sequence Data Regulatory Sequences Nucleic Acid Biology DNA-binding protein Phosphoamino acid analysis Proto-Oncogene Protein c-ets-2 Conserved sequence Proto-Oncogene Protein c-ets-1 Transactivation ETS1 Proto-Oncogene Proteins Amino Acid Sequence Phosphorylation Enhancer Molecular Biology Conserved Sequence Binding Sites Base Sequence Proto-Oncogene Proteins c-ets Cell Biology Molecular biology Cell biology DNA-Binding Proteins Repressor Proteins Enhancer Elements Genetic Mutation Trans-Activators ras Proteins Signal Transduction Transcription Factors Research Article |
| Zdroj: | Molecular and Cellular Biology. 16:538-547 |
| ISSN: | 1098-5549 |
| Popis: | The Ras oncogene products regulate the expression of genes in transformed cells, and members of the Ets family of transcription factors have been implicated in this process. To determine which Ets factors are the targets of Ras signaling pathways, the abilities of several Ets factors to activate Ras- responsive enhancer (RRE) reporters in the presence of oncogenic Ras were examined. In transient transfection assays, reporters containing RREs composed of Ets-AP-1 binding sites could be activated 30-fold in NIH 3T3 fibroblasts and 80-fold in the macrophage-like line RAW264 by the combination of Ets1 or Ets2 and Ras but not by several other Ets factors that were tested in the assay. Ets2 and Ras also superactivated an RRE composed of Ets-Ets binding sites, but the Ets-responsive promoter of the c-fms gene was not superactivated. Mutation of a threonine residue to alanine in the conserved amino-terminal regions of Ets1 and Ets2 (threonine 38 and threonine 72, respectively) abrogated the ability of each of these proteins to superactivate reporter gene expression. Phosphoamino acid analysis of radiolabeled Ets2 revealed that Ras induced normally absent threonine- specific phosphorylation of the protein. The Ras-dependent increase in threonine phosphorylation was not observed in Ets2 proteins that had the conserved threonine 72 residue mutated to alanine or serine. These data indicate that Ets1 and Ets2 are specific nuclear targets of Ras signaling events and that phosphorylation of a conserved threonine residue is a necessary molecular component of Ras-mediated activation of these transcription factors. |
| Databáze: | OpenAIRE |
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