The CK2 phosphorylation of vitronectin. Promotion of cell adhesion via the alpha(v)beta 3-phosphatidylinositol 3-kinase pathway.
Phosphorylation of vitronectin (Vn) by casein kinase II was previously shown to occur at Thr50 and Thr57 and to augment a major physiological function of vitronectin-cell adhesion and spreading. Here we show that this phosphorylation increases cell adhesion via the alpha(v)beta3 (not via the alpha(v)beta5 integrin), suggesting that alpha(v)beta3 differs from alpha(v)beta5 in its biorecognition profile. Although both the phospho (CK2-PVn) and non-phospho (Vn) analogs of vitronectin (simulated by mutants Vn(T50E,T57E), and Vn(T50A,T57A), respectively) trigger the alpha(v)beta3 as well as the alpha(v)beta5 integrins, and equally activate the ERK pathway, these two forms are different in their activation of the focal adhesion kinase/phosphatidylinositol 3-kinase (PI3K)/protein kinase B (PKB) pathway. Specifically, we show (i) that, upon exposure of cells to Vn/CK2-PVn, their PKB activation depends on the availability of the alpha(v)beta3 integrin on their surface; (ii) that upon adhesion of the beta3-transfected cells onto the CK2-PVn, the extent of PKB activation coincides with the enhanced adhesion of these cells, and (iii) that both the PKB activation and the elevation in the adhesion of these cells is PI3K-dependent. The occurrence of a cell surface receptor that specifically distinguishes between a phosphorylated and a non-phosphorylated analog of Vn, together with the fact that it preferentially activates a distinct intra-cellular signaling pathway, suggest that extra-cellular CK2 phosphorylation may play an important role in the regulation of cell adhesion and migration.
Department of Biological Regulation, The Weizmann Institute of Science, Rehovot IL-76100, Israel.
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D019943:Amino Acid Substitution; D000906:Antibodies / Q000494:pharmacology; D047390:Casein Kinase II; D002448:Cell Adhesion / Q000502:physiology*; D002460:Cell Line; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006367:HeLa Cells; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D007700:Kinetics; D020935:MAP Kinase Signaling System / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008954:Models, Biological; D016297:Mutagenesis, Site-Directed; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D019030:Receptors, Vitronectin / Q000502:physiology*; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013379:Substrate Specificity; D013912:Threonine / Q000378:metabolism; D019096:Vitronectin / Q000737:chemistry / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases
D000906:Antibodies; D047390:Casein Kinase II; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D019030:Receptors, Vitronectin; D011994:Recombinant Proteins; D013912:Threonine; D019096:Vitronectin; D048051:p38 Mitogen-Activated Protein Kinases; C496050:PTK2 protein, human