Distinct domains in the SHP-2 phosphatase differentially regulate epidermal growth factor receptor/NF-kappaB activation through Gab1 in glioblastoma cells.
The transcription factor nuclear factor kappaB (NF-kappaB) plays an important role in inflammation and cancer, is activated by a variety of stimuli including tumor necrosis factor alpha, interleukin-1, UV irradiation, and viruses, as well as receptor tyrosine kinases, such as epidermal growth factor receptor (EGFR). Although previous studies suggest that ... EGFR can induce NF-kappaB, the mechanism of this activation remains unknown. In this study, we identify the components of the EGFR-induced signalosome in human glioblastoma cells required to regulate NF-kappaB activation. Immunoprecipitation analyses with ErbB-modulated cells indicate that association between SHP-2 and Grb2-associated binder 1 (Gab1) is the critical step in the formation of the signalosome linking EGFR to NF-kappaB activation. We also show that EGFR-induced NF-kappaB activation is mediated by the PI3-kinase/Akt activation loop. Overexpression of SHP-2, Gab1, and myristoylated Akt significantly upregulated NF-kappaB transcriptional activity and DNA binding activity in glioblastoma cells. Interestingly, overexpression of either one of the two SH2 domain mutants of SHP-2, R32E or R138E, slightly reduced NF-kappaB activity relative to that of wild-type SHP-2, indicating that the SH2 domains of SHP-2 are required for EGFR-induced NF-kappaB activation. On the other hand, ectopic overexpression of either a Gab1 mutant incapable of binding to SHP-2 (Y627F) or a phosphatase-inactive SHP-2 mutant (C459S) caused a significant increase in NF-kappaB activity. Moreover, SHP-2 C459S-expressing cells displayed higher Gab1 phosphotyrosine content, suggesting that SHP-2 regulates Gab1 phosphorylation through its phosphatase domain, which confers a negative regulatory effect on NF-kappaB activity. These results indicate that SHP-2/Gab1 association is critical for linking EGFR to NF-kappaB transcriptional activity via the PI3-kinase/Akt signaling axis in glioblastoma cells and that SHP-2 acts as a dual regulator of NF-kappaB activation.
Mesh Terms:
Adaptor Proteins, Signal Transducing, Base Sequence, Cell Line, Tumor, DNA, Neoplasm, Glioblastoma, Humans, Intracellular Signaling Peptides and Proteins, Models, Biological, Mutagenesis, Site-Directed, NF-kappa B, Phosphatidylinositol 3-Kinases, Phosphoproteins, Phosphorylation, Protein Tyrosine Phosphatase, Non-Receptor Type 11, Protein Tyrosine Phosphatases, Protein-Serine-Threonine Kinases, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-akt, Receptor, Epidermal Growth Factor, Recombinant Proteins, SH2 Domain-Containing Protein Tyrosine Phosphatases, Signal Transduction, src Homology Domains
Adaptor Proteins, Signal Transducing, Base Sequence, Cell Line, Tumor, DNA, Neoplasm, Glioblastoma, Humans, Intracellular Signaling Peptides and Proteins, Models, Biological, Mutagenesis, Site-Directed, NF-kappa B, Phosphatidylinositol 3-Kinases, Phosphoproteins, Phosphorylation, Protein Tyrosine Phosphatase, Non-Receptor Type 11, Protein Tyrosine Phosphatases, Protein-Serine-Threonine Kinases, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-akt, Receptor, Epidermal Growth Factor, Recombinant Proteins, SH2 Domain-Containing Protein Tyrosine Phosphatases, Signal Transduction, src Homology Domains
Mol. Cell. Biol.
Date: Jan. 01, 2004
PubMed ID: 14701753
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