title: Recruitment of Pyk2 and Cbl to lipid rafts mediates signals important for actin reorganization in growing neurites.
abstract: Protein tyrosine kinase Pyk2 and multifunctional adaptor protein Cbl are implicated in the regulation of the cytoskeleton in several cell types. We report that Pyk2 and Cbl form a signaling complex that is translocated to lipid rafts and is enriched in growth cones of differentiating PC12 cells following growth factor stimulation. We found that Pyk2 and Cbl interacted with the adaptor protein ArgBP2, which also bound to flotillin-1, a component of lipid raft microdomains. These interactions contributed to recruitment of the Pyk2/Cbl complex to lipid raft compartments. In addition, Pyk2, Cbl and ArgBP2 were found co-localized with actin in axons and growth cones of differentiated PC12 cells. Moreover, co-expression of Pyk2, ArgBP2 and Cbl facilitated growth factor-induced formation of lamellipodia at the tip of neurites. Formation of these growth cone lamellipodia was dependent on intact lipid rafts and the Cbl-associated effectors Crk and phosphatidylinositol 3 (PI 3)-kinase. Our results indicate that recruitment of Pyk2/Cbl complexes to lipid rafts participates in growth factor-induced regulation of the actin cytoskeleton in growing neurites.
authors.affiliation: Institute for Biochemistry II, Building 75, Goethe University Medical School, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany.
authors.forename: Kaisa
authors.initials: K
authors.lastname: Haglund
authors.forename: Inga
authors.initials: I
authors.lastname: Ivankovic-Dikic
authors.forename: Noriaki
authors.initials: N
authors.lastname: Shimokawa
authors.forename: Gary D
authors.initials: GD
authors.lastname: Kruh
authors.forename: Ivan
authors.initials: I
authors.lastname: Dikic
mesh_terms: D000199:Actins / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001369:Axons / Q000378:metabolism; D002454:Cell Differentiation; D002460:Cell Line; D004815:Epidermal Growth Factor / Q000494:pharmacology; D051418:Focal Adhesion Kinase 2; D020439:Growth Cones / Q000187:drug effects / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism; D006801:Humans; D021962:Membrane Microdomains / Q000737:chemistry / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D008954:Models, Biological; D016501:Neurites / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D016716:PC12 Cells; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D050721:Proto-Oncogene Proteins c-cbl; D011554:Pseudopodia / Q000187:drug effects / Q000378:metabolism; D016601:RNA-Binding Proteins; D051381:Rats; D015398:Signal Transduction; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*
chemical_list: D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; D018398:Homeodomain Proteins; D008565:Membrane Proteins; D010982:Platelet-Derived Growth Factor; D011518:Proto-Oncogene Proteins; D016601:RNA-Binding Proteins; C490755:SORBS2 protein, human; C106354:flotillins; D004815:Epidermal Growth Factor; D050721:Proto-Oncogene Proteins c-cbl; D044767:Ubiquitin-Protein Ligases; D011505:Protein-Tyrosine Kinases; D051418:Focal Adhesion Kinase 2; C496054:Ptk2b protein, rat; C067419:CBL protein, human