TY - JOUR
T1 - Grb2 regulation of the actin-based cytoskeleton is required for ligand-independent EGF receptor-mediated oncogenesis.
AU - Boerner, Julie L.
AU - Danielsen, Andrew J.
AU - Lovejoy, Courtney A.
AU - Wang, Z.
AU - Juneja, Subhash C.
AU - Faupel-Badger, Jessica M.
AU - Darce, Jaime R.
AU - Maihle, Nita J.
N1 - Funding Information:
We gratefully acknowledge Dr Stephen Hughes (NCI) for providing the RCAN/RCAS retroviral vectors used in these studies, Dr AM Prendergast for providing the wild-type and DC mutant Grb2 cDNAs, Dr P Findell for providing the Gst-Grb2 fusion construct, and Dr T Pawson for providing the Gst-N-SH3, Gst-SH2, and Gst-C-SH3 constructs. We also thank Trace Christensen, Shari Meeker, Laura Sikkink, and Emily Ward for their technical contributions, and Drs Jill Reiter, Hakjoo Lee, and Mike McManus for their technical assistance and helpful discussions. This work was supported by the National Institutes of Health (CA79808).
PY - 2003/10/2
Y1 - 2003/10/2
N2 - Mutations within members of the EGF/ErbB receptor family frequently release the oncogenic potential of these receptors, resulting in the activation of downstream signaling events independent of ligand regulatory constraints. We previously have demonstrated that the signal transduction events originating from S3-v-ErbB, a ligand-independent, oncogenic EGF receptor mutant, are qualitatively distinct from the ligand-dependent mitogenic signaling pathways associated with the wild-type EGF receptor. Specifically, expression of S3-v-ErbB in primary fibroblasts results in anchorage-independent growth, increased invasive potential, and the formation of a transformation-specific phosphoprotein signaling complex, all in a Ras-independent manner. Here we demonstrate the transformation-specific interaction between two components of this complex: the adaptor protein Grb2 and the cytoskeletal regulatory protein caldesmon. This interaction is mediated via both the amino-terminal SH3 and central SH2 domains of Grb2, and the amino-terminal (myosin-binding) domain of caldesmon. Expression of a dominant-negative Grb2 deletion mutant, which lacks the carboxy-terminal SH3 domain, in fibroblasts expressing S3-v-ErbB results in a reduction in phosphoprotein complex formation, the loss of anchorage-independent growth, and a reduction in invasive potential. Together, these results demonstrate a Ras-independent role for Grb2 in modulating cytoskeletal function during ligand-independent EGF receptor-mediated transformation, and provide further support for the hypothesis that ligand-independent oncogenic signaling is qualitatively distinct from ligand-dependent mitogenic signaling by the EGF receptor.
AB - Mutations within members of the EGF/ErbB receptor family frequently release the oncogenic potential of these receptors, resulting in the activation of downstream signaling events independent of ligand regulatory constraints. We previously have demonstrated that the signal transduction events originating from S3-v-ErbB, a ligand-independent, oncogenic EGF receptor mutant, are qualitatively distinct from the ligand-dependent mitogenic signaling pathways associated with the wild-type EGF receptor. Specifically, expression of S3-v-ErbB in primary fibroblasts results in anchorage-independent growth, increased invasive potential, and the formation of a transformation-specific phosphoprotein signaling complex, all in a Ras-independent manner. Here we demonstrate the transformation-specific interaction between two components of this complex: the adaptor protein Grb2 and the cytoskeletal regulatory protein caldesmon. This interaction is mediated via both the amino-terminal SH3 and central SH2 domains of Grb2, and the amino-terminal (myosin-binding) domain of caldesmon. Expression of a dominant-negative Grb2 deletion mutant, which lacks the carboxy-terminal SH3 domain, in fibroblasts expressing S3-v-ErbB results in a reduction in phosphoprotein complex formation, the loss of anchorage-independent growth, and a reduction in invasive potential. Together, these results demonstrate a Ras-independent role for Grb2 in modulating cytoskeletal function during ligand-independent EGF receptor-mediated transformation, and provide further support for the hypothesis that ligand-independent oncogenic signaling is qualitatively distinct from ligand-dependent mitogenic signaling by the EGF receptor.
KW - Caldesmon
KW - EGFR/ErbB
KW - Grb2
KW - v-ErbB
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U2 - 10.1038/sj.onc.1206830
DO - 10.1038/sj.onc.1206830
M3 - Article
C2 - 14555981
AN - SCOPUS:0242606280
SN - 0950-9232
VL - 22
SP - 6679
EP - 6689
JO - Oncogene
JF - Oncogene
IS - 43
ER -