There is substantial evidence that the protooncogenic protein c-Cbl is involved in signal transduction in normal and transformed cells. c-Cbl becomes tyrosine phosphorylated in response to stimulation through a variety of receptors, as well as in the cells transformed by oncogenic forms of the protein tyrosine kinase Abl. Tyrosine phosphorylation of c-Cbl dramatically upregulates its binding to various crucial signaling molecules. However, the biological consequences of c-Cbl-mediated signal transduction are poorly understood. Recently, we have succeeded in mapping the tyrosine phosphorylation sites of c-Cbl. In order to analyze the biological functions of c-Cbl, we overexpressed wild-type c-Cbl or its mutant form lacking tyrosine phosphorylation sites in Abl-transformed fibroblasts and demonstrated that the wild-type c-Cbl suppresses transformation by oncogenic Abl, whereas the phosphorylation-defective c-Cbl enhances this transformation. The effect of wild-type c-Cbl is connected to the induction of cell adhesion and spreading on the extracellular matrix. These observations, taken together with the previous findings, led us to the hypothesis that c-Cbl recruits, in a tyrosine-phosphorylation dependent manner, PI-3 kinase and Crk-family proteins to the membrane and/or focal adhesion complexes. This, in turn, triggers signal transduction pathways facilitating the assembly of focal adhesion complexes and actin stress fibers. The tyrosine phosphorylation-dependent regulation of cell morphology and adhesion may constitute the major biological functions of c-Cbl. The overall objective of the current proposal is to test this hypothesis. Accordingly, the specific aims of our project are: 1) to determine the tyrosine phosphorylation sites of c-Cbl essential for its transformation-suppressing function; 2) to determine the relationship between the biological effects of c-Cbl tyrosine phosphorylation and the interactions of c-Cbl with the membrane, focal adhesion complexes and cytoskeleton in Abl-transformed fibroblasts; 3) to determine the relationship between PI-3 kinase- and Crk-dependent signal transduction pathways and the biological effects of c-Cbl in Abl-transformed fibroblasts; and 4) to assess the involvement of c-Cbl in biological responses to various types of extracellular stimulation mediated by protein tyrosine kinases in untransformed fibroblasts. The investigators are confident that this work will define the biological functions of c-Cbl and determine their molecular basis. This should substantially advance our understanding of normal cell activation and neoplastic transformation and may suggest novel therapeutic approaches that target signal transduction mechanisms.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
3R01CA078499-03S1
Application #
6324406
Study Section
Pathology B Study Section (PTHB)
Project Start
1998-07-01
Project End
2001-06-30
Budget Start
2000-07-01
Budget End
2001-06-30
Support Year
3
Fiscal Year
2000
Total Cost
$29,661
Indirect Cost
Name
Temple University
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
City
Philadelphia
State
PA
Country
United States
Zip Code
19122
Thomas, Dafydd H; Getz, Todd M; Newman, Tiffanny N et al. (2010) A novel histidine tyrosine phosphatase, TULA-2, associates with Syk and negatively regulates GPVI signaling in platelets. Blood 116:2570-8
Daniel, James L; Dangelmaier, Carol A; Mada, Sripal et al. (2010) Cbl-b is a novel physiologic regulator of glycoprotein VI-dependent platelet activation. J Biol Chem 285:17282-91
Agrawal, Rachana; Carpino, Nick; Tsygankov, Alexander (2008) TULA proteins regulate activity of the protein tyrosine kinase Syk. J Cell Biochem 104:953-64
Salerno, Dominic; Hasham, Muneer G; Marshall, Renee et al. (2007) Direct inhibition of CDK9 blocks HIV-1 replication without preventing T-cell activation in primary human peripheral blood lymphocytes. Gene 405:65-78
Swaminathan, G; Feshchenko, E A; Tsygankov, A Y (2007) c-Cbl-facilitated cytoskeletal effects in v-Abl-transformed fibroblasts are regulated by membrane association of c-Cbl. Oncogene 26:4095-105
Collingwood, Therese S; Smirnova, Evgeniya V; Bogush, Marina et al. (2007) T-cell ubiquitin ligand affects cell death through a functional interaction with apoptosis-inducing factor, a key factor of caspase-independent apoptosis. J Biol Chem 282:30920-8
Swaminathan, Gayathri; Tsygankov, Alexander Y (2006) The Cbl family proteins: ring leaders in regulation of cell signaling. J Cell Physiol 209:21-43
Teckchandani, Anjali M; Birukova, Anna A; Tar, Krisztina et al. (2005) The multidomain protooncogenic protein c-Cbl binds to tubulin and stabilizes microtubules. Exp Cell Res 306:114-27
Dangelmaier, Carol A; Quinter, Patricia G; Jin, Jianguo et al. (2005) Rapid ubiquitination of Syk following GPVI activation in platelets. Blood 105:3918-24
Teckchandani, Anjali M; Panetti, Tracee S; Tsygankov, Alexander Y (2005) c-Cbl regulates migration of v-Abl-transformed NIH 3T3 fibroblasts via Rac1. Exp Cell Res 307:247-58

Showing the most recent 10 out of 18 publications