PKC-dependent activation of FAK and src induces tyrosine phosphorylation of Cas and formation of Cas-Crk complexes.
SH-SY5Y neuroblastoma cells are a well-characterized model for studying the induction of neuronal differentiation. TPA treatment of these cells induces cytoskeletal rearrangements that ultimately result in neurite extension. However, the signaling pathways that precede these changes are poorly understood. Other investigators have shown that TPA treatment of SH-SY5Y cells results in increased tyrosine phosphorylation of cytoskeletal-associated proteins, including the adapter protein Cas. In this report, we examine the events upstream and downstream of Cas phosphorylation. We show that TPA treatment induces the PKC-dependent association of tyrosine-phosphorylated Cas with Crk. The activity of two protein tyrosine kinases, Src and FAK, was shown to be necessary and sufficient for TPA-induced Cas phosphorylation. We propose that the PKC-dependent phosphorylation of Cas by Src and FAK promotes the establishment of Cas-Crk complexes and that these interactions may play an important role in regulating the actin cytoskeleton during neuronal differentiation.
Department of Microbiology, University of Virginia School of Medicine, Charlottesville, Virginia, 22908-0734, USA.
P J
PJ
Bruce-Staskal
A H
AH
Bouton
D050719:Crk-Associated Substrate Protein; D004789:Enzyme Activation; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D015870:Gene Expression; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D011506:Proteins; D011518:Proto-Oncogene Proteins; D050737:Proto-Oncogene Proteins c-crk; D050717:Retinoblastoma-Like Protein p130; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism; D019061:src-Family Kinases / Q000378:metabolism*
C493841:BCAR1 protein, human; D050719:Crk-Associated Substrate Protein; D007527:Isoenzymes; D010750:Phosphoproteins; D011506:Proteins; D011518:Proto-Oncogene Proteins; D050737:Proto-Oncogene Proteins c-crk; D050717:Retinoblastoma-Like Protein p130; D014443:Tyrosine; D011494:Protein Kinases; C113183:FAK-related nonkinase; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human; D019061:src-Family Kinases; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate