PTP alpha regulates integrin-stimulated FAK autophosphorylation and cytoskeletal rearrangement in cell spreading and migration

J Cell Biol. 2003 Jan 6;160(1):137-46. doi: 10.1083/jcb.200206049. Epub 2003 Jan 6.

Abstract

We investigated the molecular and cellular actions of receptor protein tyrosine phosphatase (PTP) alpha in integrin signaling using immortalized fibroblasts derived from wild-type and PTP alpha-deficient mouse embryos. Defects in PTP alpha-/- migration in a wound healing assay were associated with altered cell shape and focal adhesion kinase (FAK) phosphorylation. The reduced haptotaxis to fibronectin (FN) of PTP alpha-/- cells was increased by expression of active (but not inactive) PTP alpha. Integrin-mediated formation of src-FAK and fyn-FAK complexes was reduced or abolished in PTP alpha-/- cells on FN, concomitant with markedly reduced phosphorylation of FAK at Tyr397. Reintroduction of active (but not inactive) PTP alpha restored FAK Tyr-397 phosphorylation. FN-induced cytoskeletal rearrangement was retarded in PTP alpha-/- cells, with delayed filamentous actin stress fiber assembly and focal adhesion formation. This mimicked the effects of treating wild-type fibroblasts with the src family protein tyrosine kinase (Src-PTK) inhibitor PP2. These results, together with the reduced src/fyn tyrosine kinase activity in PTP alpha-/- fibroblasts (Ponniah et al., 1999; Su et al., 1999), suggest that PTP alpha functions in integrin signaling and cell migration as an Src-PTK activator. Our paper establishes that PTP alpha is required for early integrin-proximal events, acting upstream of FAK to affect the timely and efficient phosphorylation of FAK Tyr-397.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenoviridae / metabolism
  • Animals
  • Catalysis
  • Cell Adhesion
  • Cell Movement
  • Culture Media, Serum-Free / pharmacology
  • Cytoskeleton / metabolism*
  • Fibroblasts / metabolism
  • Fibronectins / metabolism
  • Focal Adhesion Kinase 1
  • Focal Adhesion Protein-Tyrosine Kinases
  • Immunoblotting
  • Integrins / metabolism*
  • Mice
  • Microscopy, Fluorescence
  • Phosphorylation*
  • Precipitin Tests
  • Protein Tyrosine Phosphatases / metabolism*
  • Protein Tyrosine Phosphatases / physiology*
  • Protein-Tyrosine Kinases / metabolism*
  • Receptor-Like Protein Tyrosine Phosphatases, Class 4
  • Receptors, Cell Surface*
  • Tyrosine / metabolism
  • Vinculin / biosynthesis

Substances

  • Culture Media, Serum-Free
  • Fibronectins
  • Integrins
  • Receptors, Cell Surface
  • Vinculin
  • Tyrosine
  • Protein-Tyrosine Kinases
  • Focal Adhesion Kinase 1
  • Focal Adhesion Protein-Tyrosine Kinases
  • Ptk2 protein, mouse
  • Protein Tyrosine Phosphatases
  • Ptpra protein, mouse
  • Receptor-Like Protein Tyrosine Phosphatases, Class 4