Roles for the tubulin- and PTP-PEST-binding paxillin LIM domains in cell adhesion and motility

Int J Biochem Cell Biol. 2002 Jul;34(7):855-63. doi: 10.1016/s1357-2725(01)00154-6.

Abstract

Cell dynamics mediated through cell-extracellular matrix contacts, such as adhesion and motility involve the precise regulation of large complexes of structural and signaling molecules called focal adhesions (FAs). Paxillin is a multi-domain FA adaptor protein containing five amino-terminal paxillin leucine-aspartate repeat (LD) motifs and four carboxyl-terminal Lin-11 Isl-1 and Mec-3 (LIM) domains. The LD motifs support paxillin binding to actopaxin, integrin linked kinase (ILK), FA kinase (FAK), paxillin kinase linker (PKL) and vinculin. Of the LIM domains, LIM2 and 3 comprise the paxillin FA-targeting motif, with phosphorylation of these domains modulating paxillin targeting and cell adhesion to fibronectin (Fn). The identity of the paxillin FA targeting partner remains to be determined; however, the LIM domains mediate interactions with tubulin and the protein-tyrosine phosphatase (PTP)-PEST. PTP-PEST binding requires both LIM3 and 4, whereas, the precise LIM target of tubulin binding is not known. In this report, we demonstrate that the individual paxillin LIM2 and 3 domains support specific binding to tubulin and suggest a potential role for this interaction in the regulation of paxillin sub-cellular compartmentalization. In addition, expression of paxillin molecules with mutations in the tubulin- and PTP-PEST-binding LIM domains differentially impaired Chinese hamster ovary K1 (CHO.K1) cell adhesion and migration to Fn. Perturbation of LIM3 or 4 inhibited adhesion while mutation of LIM2 or 4 decreased cell motility. Interestingly, expression of tandem LIM2-3 inhibited cell adhesion and spreading while LIM3-4 stimulated a well-spread polarized phenotype. These data offer further support for a critical role for paxillin in cell adhesion and motility.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Binding Sites
  • CHO Cells
  • Cell Adhesion / physiology*
  • Cell Movement / physiology*
  • Cricetinae
  • Cytoskeletal Proteins / chemistry*
  • Cytoskeletal Proteins / genetics
  • Cytoskeletal Proteins / physiology*
  • Fibronectins / metabolism
  • Paxillin
  • Phosphoproteins / chemistry*
  • Phosphoproteins / genetics
  • Phosphoproteins / physiology*
  • Protein Structure, Tertiary
  • Protein Tyrosine Phosphatase, Non-Receptor Type 12
  • Protein Tyrosine Phosphatases / metabolism
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Tubulin / chemistry*
  • Tubulin / genetics
  • Tubulin / physiology*

Substances

  • Cytoskeletal Proteins
  • Fibronectins
  • Paxillin
  • Phosphoproteins
  • Recombinant Proteins
  • Tubulin
  • Protein Tyrosine Phosphatase, Non-Receptor Type 12
  • Protein Tyrosine Phosphatases