c-Cbl-facilitated cytoskeletal effects in v-Abl-transformed fibroblasts are regulated by membrane association of c-Cbl.
The multi-functional protein c-Cbl is an important modulator of actin cytoskeletal dynamics in diverse biological systems. We had previously reported that c-Cbl facilitates cell spreading and adhesion and suppresses anchorage-independent growth of v-Abl-transformed fibroblasts. To assess the importance of membrane localization of c-Cbl for the observed effects of c-Cbl in v-Abl-3T3 cells, we first mapped the membrane interactive domain(s) of c-Cbl. Our studies indicate that localization of c-Cbl to the membrane is likely to be mediated by the tyrosine kinase binding (TKB) domain and the proline-rich region of c-Cbl, whereas C-terminal tyrosine phosphorylation does not play a role. The association of v-Cbl, which encompasses the TKB domain, with the membrane was unusual as it was not entirely dependent on SH2-phosphotyrosine interactions. Our studies further demonstrate that Src-like adaptor protein (SLAP), which binds to v-Cbl in a tyrosine phosphorylation-independent manner, facilitates membrane association of Cbl. The interaction between c-Cbl and SLAP in v-Abl-3T3 cells positively influenced c-Cbl-mediated spreading and adhesion of these cells. SLAP appears to exert its effects not simply by increasing the amount of c-Cbl in the membrane but by facilitating binding of p85-phosphatidylinositol-3-kinase (PI3K) with membrane-associated c-Cbl.
Swaminathan
G
G
Department of Microbiology and Immunology, Temple University School of Medicine, Philadelphia, PA 19104, USA.
Feshchenko
E A
EA
Tsygankov
A Y
AY
D016475:3T3 Cells; D000818:Animals; D019556:COS Cells; D002471:Cell Transformation, Neoplastic; D002522:Chlorocebus aethiops; D005347:Fibroblasts / Q000166:cytology*; D006801:Humans; D019169:Jurkat Cells; D051379:Mice; D016374:Oncogene Proteins v-abl / Q000502:physiology*; D010766:Phosphorylation; D050721:Proto-Oncogene Proteins c-cbl / Q000502:physiology*
D016374:Oncogene Proteins v-abl; D050721:Proto-Oncogene Proteins c-cbl; C067419:CBL protein, human