Differential regulation of Pyk2 phosphorylation at Tyr-402 and Tyr-580 in intestinal epithelial cells: Roles of calcium, Src, Rho kinase, and the cytoskeleton
Autor: | Sheung K. Vong, Steven S. Wu, Enrique Rozengurt, Rodrigo Jacamo |
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Rok vydání: | 2006 |
Předmět: |
PTK2
Protein Serine-Threonine Kinases Biology Phosphorylation cascade chemistry.chemical_compound Animals Humans Protein phosphorylation Intestinal Mucosa Phosphorylation Cells Cultured Cytoskeleton MAPK14 rho-Associated Kinases Angiotensin II Autophosphorylation Intracellular Signaling Peptides and Proteins Tyrosine phosphorylation Cell Biology Cell biology Focal Adhesion Kinase 2 src-Family Kinases chemistry Tyrosine Calcium Signal Transduction Proto-oncogene tyrosine-protein kinase Src |
Zdroj: | Cellular Signalling. 18:1932-1940 |
ISSN: | 0898-6568 |
Popis: | The calcium-dependent proline-rich tyrosine kinase Pyk2 is activated by tyrosine phosphorylation, associates with focal adhesion proteins, and has been linked to proliferative and migratory responses in a variety of mesenchymal and epithelial cell types. Full Pyk2 activation requires phosphorylation at functionally distinct sites, including autophosphorylation site Tyr-402 and catalytic domain site Tyr-580, though the mechanisms involved are unclear. The pathways mediating Pyk2 phosphorylation at Tyr-402 and Tyr-580 were therefore investigated. Both sites were rapidly and transiently phosphorylated following cell stimulation by Ang II or LPA. However, only Tyr-580 phosphorylation was rapidly enhanced by intracellular Ca2+ release, or inhibited by Ca2+ depletion. Conversely, Tyr-402 phosphorylation was highly sensitive to inhibition of actin stress fibers, or of Rho kinase (ROK), an upstream regulator of stress fiber assembly. Ang II also induced a delayed (30–60 min) secondary phosphorylation peak occurring at Tyr-402 alone. Unlike the homologous focal adhesion kinase (FAK), Pyk2 phosphorylation was sensitive neither to the Src inhibitor PP2, nor to truncation of its N-terminal region, which contains a putative autoinhibitory FERM domain. These results better define the mechanisms involved in Pyk2 activation, demonstrating that autophosphorylation is ROK- and stress fiber-dependent, while transphosphorylation within the kinase domain is Ca2+-dependent and Src-independent in intestinal epithelial cells. This contrasts with the tight sequential coupling of phosphorylation seen in FAK activation, and further underlines the differences between these closely related kinases. |
Databáze: | OpenAIRE |
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