Profilin Regulates F-actin Network Homeostasis by Favoring Formin Over Arp2/3 Complex

Dev Cell. 2015 Jan 12;32(1):43-53. doi: 10.1016/j.devcel.2014.10.027. Epub 2014 Dec 24.

Abstract

Fission yeast cells use Arp2/3 complex and formin to assemble diverse filamentous actin (F-actin) networks within a common cytoplasm for endocytosis, division, and polarization. Although these homeostatic F-actin networks are usually investigated separately, competition for a limited pool of actin monomers (G-actin) helps to regulate their size and density. However, the mechanism by which G-actin is correctly distributed between rival F-actin networks is not clear. Using a combination of cell biological approaches and in vitro reconstitution of competition between actin assembly factors, we found that the small G-actin binding protein profilin directly inhibits Arp2/3 complex-mediated actin assembly. Profilin is therefore required for formin to compete effectively with excess Arp2/3 complex for limited G-actin and to assemble F-actin for contractile ring formation in dividing cells.

Publication types

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

MeSH terms

  • Actin Cytoskeleton / metabolism*
  • Actin-Related Protein 2-3 Complex / metabolism*
  • Actins / metabolism*
  • Endocytosis / physiology
  • Homeostasis / physiology*
  • Image Processing, Computer-Assisted
  • Microscopy, Fluorescence
  • Profilins / metabolism*
  • Schizosaccharomyces / metabolism*
  • Schizosaccharomyces pombe Proteins / metabolism*

Substances

  • Actin-Related Protein 2-3 Complex
  • Actins
  • Profilins
  • Schizosaccharomyces pombe Proteins