title: Novel Role of Src in Priming Pyk2 Phosphorylation.
abstract: Proline-rich tyrosine kinase 2 (Pyk2) is a member of the focal adhesion kinase (FAK) family of non-receptor tyrosine kinases and plays an important role in diverse cellular events downstream of the integrin-family of receptors, including cell migration, proliferation and survival. Here, we have identified a novel role for Src kinase in priming Pyk2 phosphorylation and subsequent activation upon cell attachment on the integrin-ligand fibronectin. By using complementary methods, we show that Src activity is indispensable for the initial Pyk2 phosphorylation on the Y402 site observed in response to cell attachment. In contrast, the initial fibronectin-induced autophosphorylation of FAK in the homologous Y397 site occurs in a Src-independent manner. We demonstrate that the SH2-domain of Src is required for Src binding to Pyk2 and for Pyk2 phosphorylation at sites Y402 and Y579. Moreover, Y402 phosphorylation is a prerequisite for the subsequent Y579 phosphorylation. While this initial phosphorylation of Pyk2 by Src is independent of Pyk2 kinase activity, subsequent autophosphorylation of Pyk2 in trans is required for full Pyk2 phosphorylation and activation. Collectively, our studies reveal a novel function of Src in priming Pyk2 (but not FAK) phosphorylation and subsequent activation downstream of integrins, and shed light on the signaling events that regulate the function of Pyk2.
authors: Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, 10901 N. Torrey Pines Road, La Jolla, California, United States of America.
authors: Ming
authors: M
authors: Zhao
authors: Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, 10901 N. Torrey Pines Road, La Jolla, California, United States of America.
authors: Darren
authors: D
authors: Finlay
authors: Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, 10901 N. Torrey Pines Road, La Jolla, California, United States of America.
authors: Irina
authors: I
authors: Zharkikh
authors: Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, 10901 N. Torrey Pines Road, La Jolla, California, United States of America.
authors: Kristiina
authors: K
authors: Vuori
mesh_terms: D000818:Animals; D002448:Cell Adhesion; D002465:Cell Movement; D049109:Cell Proliferation; D005347:Fibroblasts / Q000378:metabolism; D005353:Fibronectins / Q000378:metabolism; D051418:Focal Adhesion Kinase 2 / Q000378:metabolism*; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000378:metabolism; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D016023:Integrins / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D010766:Phosphorylation; D011485:Protein Binding; D051076:Proto-Oncogene Proteins c-fyn / Q000235:genetics; D051575:Proto-Oncogene Proteins c-yes / Q000235:genetics; D015398:Signal Transduction; D018909:src Homology Domains; D019061:src-Family Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D005353:Fibronectins; D016023:Integrins; C494957:FYN protein, human; D051418:Focal Adhesion Kinase 2; D051416:Focal Adhesion Protein-Tyrosine Kinases; C494960:Fyn protein, mouse; D051076:Proto-Oncogene Proteins c-fyn; D051575:Proto-Oncogene Proteins c-yes; C496053:Ptk2b protein, mouse; C489834:YES1 protein, human; C496639:Yes1 protein, mouse; D019061:src-Family Kinases