α-actinin1 and 4 tyrosine phosphorylation is critical for stress fiber establishment, maintenance and focal adhesion maturation

Exp Cell Res. 2013 May 1;319(8):1124-35. doi: 10.1016/j.yexcr.2013.02.009. Epub 2013 Feb 27.

Abstract

In polarized, migrating cells, stress fibers are a highly dynamic network of contractile acto-myosin structures composed of bundles of actin filaments held together by actin cross-linking proteins such as α-actinins. As such, α-actinins influence actin cytoskeleton organization and dynamics and focal adhesion maturation. In response to environmental signals, α-actinins are tyrosine phosphorylated and this affects their binding to actin stress fibers; however, the cellular role of α-actinin tyrosine phosphorylation remains largely unknown. We found that non-muscle α-actinin1/4 are critical for the establishment of dorsal stress fibers and maintenance of transverse arc stress fibers. Analysis of cells genetically depleted of α-actinin1 and 4 reveals two distinct modes for focal adhesion maturation. An α-actinin1 or 4 dependent mode that uses dorsal stress fiber precursors as a template for establishing focal adhesions and their maturation, and an α-actinin-independent manner that uses transverse arc precursors to establish focal adhesions at both ends. Focal adhesions formed in the absence of α-actinins are delayed in their maturation, exhibit altered morphology, have decreased amounts of Zyxin and VASP, and reduced adhesiveness to extracellular matrix. Further rescue experiments demonstrate that the tyrosine phosphorylation of α-actinin1 at Y12 and α-actinin4 at Y265 is critical for dorsal stress fiber establishment, transverse arc maintenance and focal adhesion maturation.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Actinin / genetics
  • Actinin / metabolism*
  • Actinin / physiology
  • Cell Adhesion / genetics
  • Cell Adhesion Molecules / metabolism
  • Cell Differentiation / genetics
  • Cell Differentiation / physiology
  • Cell Line, Tumor
  • Focal Adhesion Kinase 1 / metabolism
  • Focal Adhesions / chemistry
  • Focal Adhesions / genetics
  • Focal Adhesions / metabolism
  • Focal Adhesions / physiology*
  • HEK293 Cells
  • Humans
  • Microfilament Proteins / metabolism
  • Paxillin / metabolism
  • Phosphoproteins / metabolism
  • Phosphorylation / genetics
  • Phosphorylation / physiology
  • Protein-Tyrosine Kinases / metabolism*
  • Protein-Tyrosine Kinases / physiology
  • Stress Fibers / metabolism*
  • Stress Fibers / physiology*
  • Tyrosine / genetics
  • Tyrosine / metabolism
  • Zyxin / metabolism

Substances

  • ACTN1 protein, human
  • ACTN4 protein, human
  • Cell Adhesion Molecules
  • Microfilament Proteins
  • PXN protein, human
  • Paxillin
  • Phosphoproteins
  • ZYX protein, human
  • Zyxin
  • vasodilator-stimulated phosphoprotein
  • Actinin
  • Tyrosine
  • Protein-Tyrosine Kinases
  • Focal Adhesion Kinase 1
  • PTK2 protein, human