Constitutive association of EGF receptor with the CrkII-23 mutant that inhibits transformation of NRK cells by EGF and TGF-beta.
Crk belongs to the adapter proteins that participate in many signalling pathways from cell surface receptors. We have characterised the CrkII-23 mutant that inhibits the transformation of NRK cells induced by epidermal growth factor (EGF) and transforming growth factor (TGF)-beta. To study the biochemical difference, cDNAs of the wild-type CrkII ... and the CrkII-23 mutant were introduced stably into NIH 3T3 cells expressing EGF receptor (EGFR). Both CrkII and CrkII-23 were phosphorylated on tyrosine upon EGF simulation with similar time course and dose dependency. Whereas the wild-type CrkII bound to EGFR only after EGF stimulation, CrkII-23 bound to EGFR from before stimulation. Mutation in the Src homology (SH) 2 or amino-terminal SH3 domain did not abolish the binding of CrkII-23 to EGFR in the quiescent cells, suggesting that the binding is mediated by a novel mechanism. These CrkII-23-derived mutants, however, did not suppress transformation of NRK cells by EGF and TGF-beta. Hence, both the SH2 and amino-terminal SH3 domains are required to inhibit transformation of NRK cells. These results suggest that persistent signalling from CrkII-23 bound to EGFR suppresses transformation by EGF and TGF-beta in NRK23 cells.
Mesh Terms:
3T3 Cells, Adaptor Proteins, Signal Transducing, Adaptor Proteins, Vesicular Transport, Animals, COS Cells, Cell Differentiation, Cell Transformation, Neoplastic, DNA Mutational Analysis, Epidermal Growth Factor, Eukaryotic Initiation Factor-2, Guanine Nucleotide Exchange Factors, Humans, Mice, Mutation, Neurons, PC12 Cells, Phosphorylation, Protein Binding, Protein Kinases, Protein Structure, Tertiary, Proteins, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-abl, Proto-Oncogene Proteins c-cbl, Proto-Oncogene Proteins c-crk, Rats, Receptor, Epidermal Growth Factor, Shc Signaling Adaptor Proteins, Transforming Growth Factor beta, Tyrosine, Ubiquitin-Protein Ligases, src Homology Domains
3T3 Cells, Adaptor Proteins, Signal Transducing, Adaptor Proteins, Vesicular Transport, Animals, COS Cells, Cell Differentiation, Cell Transformation, Neoplastic, DNA Mutational Analysis, Epidermal Growth Factor, Eukaryotic Initiation Factor-2, Guanine Nucleotide Exchange Factors, Humans, Mice, Mutation, Neurons, PC12 Cells, Phosphorylation, Protein Binding, Protein Kinases, Protein Structure, Tertiary, Proteins, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-abl, Proto-Oncogene Proteins c-cbl, Proto-Oncogene Proteins c-crk, Rats, Receptor, Epidermal Growth Factor, Shc Signaling Adaptor Proteins, Transforming Growth Factor beta, Tyrosine, Ubiquitin-Protein Ligases, src Homology Domains
Cell. Signal.
Date: Apr. 01, 1998
PubMed ID: 9617486
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