Rapid phosphorylation of Ets-2 accompanies mitogen-activated protein kinase activation and the induction of heparin-binding epidermal growth factor gene expression by oncogenic Raf-1.
AUTOR(ES)
McCarthy, S A
RESUMO
Heparin-binding epidermal growth factor (HB-EGF) gene transcription is rapidly activated in NIH 3T3 cells transformed by oncogenic Ras and Raf and mediates the autocrine activation of the c-Jun N-terminal kinases (JNKs) observed in these cells. A 1.7-kb fragment of the promoter of the murine HB-EGF gene linked to a luciferase reporter was strongly induced following activation of deltaRaf-1:ER, a conditionally active form of oncogenic human Raf-1. Promoter activation by deltaRaf-1:ER required a composite AP-1/Ets transcription factor binding site located between bp -974 and -988 upstream of the translation initiation site. In vivo genomic footprinting indicated that the basal level of occupancy of this composite AP-1/Ets element increased following deltaRaf-1:ER activation. Cotransfection of Ets-2 and p44 mitogen-activated protein (MAP) kinase expression vectors strongly potentiated HB-EGF promoter activation in response to deltaRaf-1:ER. Potentiated activation required both p44 MAP kinase catalytic activity and threonine 72 in the Pointed domain of Ets-2. Biochemical assays demonstrated the ability of the p42 and p44 MAP kinases to phosphorylate Ets-2 on threonine 72. Importantly, in intact cells, the kinetics of phosphorylation of Ets-2 on this residue closely mirror the activation of the p42 and p44 MAP kinases and the observed onset of HB-EGF gene transcription following deltaRaf-1:ER activation. These data firmly establish Ets-2 as a direct target of the Raf-MEK-MAP kinase signaling pathway and strongly implicate Ets-2 in the regulation of HB-EGF gene expression.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=232089Documentos Relacionados
- Heparin-binding epidermal growth factor-like growth factor, a v-Jun target gene, induces oncogenic transformation
- Role of Phosphoinositide 3-Kinase in Activation of Ras and Mitogen-Activated Protein Kinase by Epidermal Growth Factor
- A Novel Mitogen-Activated Protein Kinase Is Responsive to Raf and Mediates Growth Factor Specificity
- Heparin-binding ligands mediate autocrine epidermal growth factor receptor activation In skin organ culture.
- Structure of the Ets-1 pointed domain and mitogen-activated protein kinase phosphorylation site