Activation of cytosolic Slingshot-1 phosphatase by gelsolin-generated soluble actin filaments

Biochem Biophys Res Commun. 2014 Nov 21;454(3):471-7. doi: 10.1016/j.bbrc.2014.10.108. Epub 2014 Oct 27.

Abstract

Slingshot-1 (SSH1) is a protein phosphatase that dephosphorylates and activates cofilin, an actin-severing and -disassembling protein. SSH1 is bound to and activated by F-actin, but not G-actin. SSH1 is accumulated in the F-actin-rich lamellipodium but is also diffusely distributed in the cytoplasm. It remains unknown whether SSH1 is activated by soluble (low-level polymerized) actin filaments in the cytoplasm. In this study, we show that SSH1 binds to gelsolin via actin filaments in the cytosolic fraction. Gelsolin promoted solubilization of actin filaments and SSH1 in cell-free assays and in cultured cells. SSH1 was activated by gelsolin-generated soluble actin filaments. Furthermore, gelsolin enhanced cofilin dephosphorylation in neuregulin-stimulated cells. Our results suggest that cytosolic SSH1 forms a complex with gelsolin via soluble actin filaments and is activated by gelsolin-generated soluble actin filaments and that gelsolin promotes stimulus-induced cofilin dephosphorylation through increasing soluble actin filaments, which support SSH1 activation in the cytoplasm.

Keywords: Actin oligomers; Cofilin; Gelsolin; Phosphatase; Scinderin; Slingshot.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actin Cytoskeleton / metabolism*
  • Actin Depolymerizing Factors / metabolism
  • Cytosol / metabolism*
  • Enzyme Activation
  • Gelsolin / analysis
  • Gelsolin / metabolism*
  • Humans
  • MCF-7 Cells
  • Phosphoprotein Phosphatases / analysis
  • Phosphoprotein Phosphatases / metabolism*
  • Phosphorylation
  • Protein Binding
  • Protein Interaction Maps
  • Solubility

Substances

  • Actin Depolymerizing Factors
  • Gelsolin
  • Phosphoprotein Phosphatases
  • SSH1 protein, human