We found earlier that pl30Cas (Cas), a 130 kDa v-src substrate protein, becomes tyrosine-phosphorylated upon integrin ligand binding and may function as a molecular switch activating downstream signaling pathways via protein-protein interactions. Our recent data support a crucial role for Cas in coordinating cell growth, morphology and cell migration. Our findings demonstrate that this role of Cas is not limited to integrin signaling, but Cas also functions downstream of cytokines, growth factors and oncogenes. Most notably, complex formation between the tyrosine-phosphorylated Cas and the SH2/SH3-containing adaptor protein Crk was found to play a central role in activating one of the MAP kinase pathways, namely the JNK pathway, in response to several cellular stimuli; this finding is the first demonstration of a stimuli-induced biochemical signaling pathway downstream of the Cas-Crk complex. Taken into consideration the evidence showing an important role for JNK in a number of physiological and pathological processes, the first two Aims within this proposal focus on defining the biological significance of the Cas-Crk-JNK pathway.
In Specific Aim l, we will study whether the Cas-Crk-JNK pathway regulates such well-defined biological events as transcriptional activity and cell migration in response to integrin-mediated cell adhesion; evidence in other signaling systems suggests that activation of the Cas-Crk-JNK cascade may well have a previously unidentified crucial role in these important cellular functions. In the Specific Aim 2, we will study the possibility that inadvertent activation of the Cas-Crk-JNK pathway may aid malignant transformation. As detailed in the Research Plan, oncogenic Met receptor-expressing cells provide a highly plausible and biologically significant model system, and will be utilized in these-studies. Finally, we have observed a time-dependent cleavage of Cas in apoptotic cells, which correlates with changes in- subcellular localization of Cas.
In Specific Aim 3, we will study the functional significance of Cas cleavage in apoptosis; these studies include determining the exact cleavage sites in Cas and expression of recombinant fragments of Cas and Cas-constructs that are resistant to cleavage in mammalian cells. Once completed, these studies are expected to yield significant new information on the role of the Cas-Crk signaling complex in intracellular signaling events.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
2R01CA071560-04A1
Application #
6046169
Study Section
Pathobiochemistry Study Section (PBC)
Program Officer
Mohla, Suresh
Project Start
1996-07-10
Project End
2004-12-31
Budget Start
2000-01-24
Budget End
2000-12-31
Support Year
4
Fiscal Year
2000
Total Cost
$288,532
Indirect Cost
Name
Sanford-Burnham Medical Research Institute
Department
Type
DUNS #
009214214
City
La Jolla
State
CA
Country
United States
Zip Code
92037
Nasertorabi, Fariborz; Tars, Kaspars; Becherer, Kathleen et al. (2006) Molecular basis for regulation of Src by the docking protein p130Cas. J Mol Recognit 19:30-8
Briknarova, Klara; Nasertorabi, Fariborz; Havert, Marnie L et al. (2005) The serine-rich domain from Crk-associated substrate (p130cas) is a four-helix bundle. J Biol Chem 280:21908-14
Nasertorabi, Fariborz; Alonso, Andres; Rogers, Scott W et al. (2005) Crystallization of the SH2-binding site of p130Cas in complex with Lck, a Src-family kinase. Acta Crystallogr Sect F Struct Biol Cryst Commun 61:174-7
Nasertorabi, Fariborz; Garcia-Guzman, Miguel; Briknarova, Klara et al. (2004) Organization of functional domains in the docking protein p130Cas. Biochem Biophys Res Commun 324:993-8
Abassi, Yama A; Vuori, Kristiina (2002) Tyrosine 221 in Crk regulates adhesion-dependent membrane localization of Crk and Rac and activation of Rac signaling. EMBO J 21:4571-82
Aoudjit, F; Vuori, K (2001) Matrix attachment regulates Fas-induced apoptosis in endothelial cells: a role for c-flip and implications for anoikis. J Cell Biol 152:633-43
Garcia-Guzman, M; Larsen, E; Vuori, K (2000) The proto-oncogene c-Cbl is a positive regulator of Met-induced MAP kinase activation: a role for the adaptor protein Crk. Oncogene 19:4058-65
Aoudjit, F; Vuori, K (2000) Engagement of the alpha2beta1 integrin inhibits Fas ligand expression and activation-induced cell death in T cells in a focal adhesion kinase-dependent manner. Blood 95:2044-51
Garcia-Guzman, M; Dolfi, F; Russello, M et al. (1999) Cell adhesion regulates the interaction between the docking protein p130(Cas) and the 14-3-3 proteins. J Biol Chem 274:5762-8
Garcia-Guzman, M; Dolfi, F; Zeh, K et al. (1999) Met-induced JNK activation is mediated by the adapter protein Crk and correlates with the Gab1 - Crk signaling complex formation. Oncogene 18:7775-86

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