Cell migration requires both ion translocation and cytoskeletal anchoring by the Na-H exchanger NHE1

J Cell Biol. 2002 Dec 23;159(6):1087-96. doi: 10.1083/jcb.200208050. Epub 2002 Dec 16.

Abstract

Directed cell movement is a multi-step process requiring an initial spatial polarization that is established by asymmetric stimulation of Rho GTPases, phosphoinositides (PIs), and actin polymerization. We report that the Na-H exchanger isoform 1 (NHE1), a ubiquitously expressed plasma membrane ion exchanger, is necessary for establishing polarity in migrating fibroblasts. In fibroblasts, NHE1 is predominantly localized in lamellipodia, where it functions as a plasma membrane anchor for actin filaments by its direct binding of ezrin/radixin/moesin (ERM) proteins. Migration in a wounding assay was impaired in fibroblasts expressing NHE1 with mutations that independently disrupt ERM binding and cytoskeletal anchoring or ion transport. Disrupting either function of NHE1 impaired polarity, as indicated by loss of directionality, mislocalization of the Golgi apparatus away from the orientation of the wound edge, and inhibition of PI signaling. Both functions of NHE1 were also required for remodeling of focal adhesions. Most notably, lack of ion transport inhibited de-adhesion, resulting in trailing edges that failed to retract. These findings indicate that by regulating asymmetric signals that establish polarity and by coordinating focal adhesion remodeling at the cell front and rear, cytoskeletal anchoring by NHE1 and its localized activity in lamellipodia act cooperatively to integrate cues for directed migration.

Publication types

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

MeSH terms

  • Animals
  • Biological Transport
  • Calpain / metabolism
  • Cell Adhesion
  • Cell Membrane / metabolism
  • Cell Movement
  • Collagen / pharmacology
  • Cytoskeleton / metabolism*
  • Drug Combinations
  • Fibroblasts / metabolism
  • Golgi Apparatus / metabolism
  • Green Fluorescent Proteins
  • Immunoblotting
  • Intracellular Signaling Peptides and Proteins
  • Ions*
  • Laminin / pharmacology
  • Luminescent Proteins / metabolism
  • Mice
  • Microscopy, Fluorescence
  • Models, Biological
  • Protein Binding
  • Protein Serine-Threonine Kinases / metabolism
  • Proteoglycans / pharmacology
  • Pseudopodia / metabolism
  • Sodium-Hydrogen Exchangers / metabolism
  • Sodium-Hydrogen Exchangers / physiology*
  • Time Factors
  • Transfection
  • rho-Associated Kinases

Substances

  • Drug Combinations
  • Intracellular Signaling Peptides and Proteins
  • Ions
  • Laminin
  • Luminescent Proteins
  • Proteoglycans
  • Sodium-Hydrogen Exchangers
  • growth factor-activatable Na-H exchanger NHE-1
  • matrigel
  • Green Fluorescent Proteins
  • Collagen
  • Protein Serine-Threonine Kinases
  • rho-Associated Kinases
  • Calpain