Phosphatidylinositol-4,5 bisphosphate produced by PIP5KIgamma regulates gelsolin, actin assembly, and adhesion strength of N-cadherin junctions

Mol Biol Cell. 2007 Aug;18(8):3026-38. doi: 10.1091/mbc.e06-12-1159. Epub 2007 May 30.

Abstract

Phosphoinositides regulate several actin-binding proteins but their role at intercellular adhesions has not been defined. We found that phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) was generated at sites of N-cadherin-mediated intercellular adhesion and was a critical regulator of intercellular adhesion strength. Immunostaining for PI(4,5)P2 or transfection with GFP-PH-PLCdelta showed that PI(4,5)P2 was enriched at sites of N-cadherin adhesions and this enrichment required activated Rac1. Isoform-specific immunostaining for type I phosphatidylinositol 4-phosphate 5 kinase (PIP5KI) showed that PIP5KIgamma was spatially associated with N-cadherin-Fc beads. Association of PIP5KIgamma with N-cadherin adhesions was in part dependent on the activation of RhoA. Transfection with catalytically inactive PIP5KIgamma blocked the enrichment of PI(4,5)P2 around beads. Catalytically inactive PIP5KIgamma or a cell-permeant peptide that mimics and competes for the PI(4,5)P2-binding region of the actin-binding protein gelsolin inhibited incorporation of actin monomers in response to N-cadherin ligation and reduced intercellular adhesion strength by more than twofold. Gelsolin null fibroblasts transfected with a gelsolin severing mutant containing an intact PI(4,5)P2 binding region, demonstrated intercellular adhesion strength similar to wild-type transfected controls. We conclude that PIP5KIgamma-mediated generation of PI(4,5)P2 at sites of N-cadherin contacts regulates intercellular adhesion strength, an effect due in part to PI(4,5)P2-mediated regulation of gelsolin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / metabolism*
  • Animals
  • Binding, Competitive
  • Cadherins / metabolism*
  • Cell Adhesion
  • Chickens
  • Enzyme Activation
  • Fibroblasts / cytology
  • Fibroblasts / ultrastructure
  • Gelsolin / metabolism*
  • Humans
  • Isoenzymes / metabolism
  • Mice
  • NIH 3T3 Cells
  • Peptides / metabolism
  • Phosphatidylinositol 4,5-Diphosphate / metabolism*
  • Phosphotransferases (Alcohol Group Acceptor) / metabolism*
  • Protein Binding
  • Rats
  • Signal Transduction
  • rho GTP-Binding Proteins / metabolism

Substances

  • Actins
  • Cadherins
  • Gelsolin
  • Isoenzymes
  • Peptides
  • Phosphatidylinositol 4,5-Diphosphate
  • Phosphotransferases (Alcohol Group Acceptor)
  • PIP5KI protein, rat
  • rho GTP-Binding Proteins