Targeting Pyk2 to β1-integrin–containing focal contacts rescues fibronectin-stimulated signaling and haptotactic motility defects of focal adhesion kinase–null cells

CK Klingbeil, CR Hauck, DA Hsia, KC Jones… - The Journal of cell …, 2001 - rupress.org
CK Klingbeil, CR Hauck, DA Hsia, KC Jones, SR Reider, DD Schlaepfer
The Journal of cell biology, 2001rupress.org
Focal adhesion kinase–null (FAK−/−) fibroblasts exhibit morphological and motility defects
that are reversed by focal adhesion kinase (FAK) reexpression. The FAK-related kinase,
proline-rich tyrosine kinase 2 (Pyk2), is expressed in FAK−/− cells, yet it exhibits a
perinuclear distribution and does not functionally substitute for FAK. Chimeric Pyk2/FAK
proteins were created and expressed in FAK−/− cells to determine the impact of Pyk2
localization to focal contacts. Whereas an FAK/Pyk2 COOH-terminal (CT) domain chimera …
Focal adhesion kinase–null (FAK−/−) fibroblasts exhibit morphological and motility defects that are reversed by focal adhesion kinase (FAK) reexpression. The FAK-related kinase, proline-rich tyrosine kinase 2 (Pyk2), is expressed in FAK−/− cells, yet it exhibits a perinuclear distribution and does not functionally substitute for FAK. Chimeric Pyk2/FAK proteins were created and expressed in FAK−/− cells to determine the impact of Pyk2 localization to focal contacts. Whereas an FAK/Pyk2 COOH-terminal (CT) domain chimera was perinuclear distributed, stable expression of a Pyk2 chimera with the FAK-CT domain (Pyk2/FAK-CT) localized to focal contact sites and enhanced fibronectin (FN)-stimulated haptotactic cell migration equal to FAK-reconstituted cells. Disruption of paxillin binding to the FAK-CT domain (S-1034) inhibited Pyk2/FAK-CT localization to focal contacts and its capacity to promote cell motility. Paxillin binding to the FAK-CT was necessary but not sufficient to mediate the indirect association of FAK or Pyk2/FAK-CT with a β1-integrin–containing complex. Both FAK and Pyk2/FAK-CT but not Pyk2/FAK-CT S-1034 reconstituted FAK−/− cells, exhibit elevated FN-stimulated extracellular signal–regulated kinase 2 (ERK2) and c-Jun NH2-terminal kinase (JNK) kinase activation. FN-stimulated FAK or Pyk2/FAK-CT activation enhanced both the extent and duration of FN-stimulated ERK2 activity which was necessary for cell motility. Transient overexpression of the FAK-CT but not FAK-CT S-1034 domain inhibited both FN-stimulated ERK2 and JNK activation as well as FN-stimulated motility of Pyk2/FAK-CT reconstituted cells. These gain-of-function studies show that the NH2-terminal and kinase domains of Pyk2 can functionally substitute for FAK in promoting FN-stimulated signaling and motility events when localized to β-integrin–containing focal contact sites via interactions mediated by the FAK-CT domain.
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