Actin cytoskeleton remodeling by the alternatively spliced isoform of PDLIM4/RIL protein

J Biol Chem. 2011 Jul 29;286(30):26849-59. doi: 10.1074/jbc.M111.241554. Epub 2011 Jun 2.

Abstract

RIL (product of PDLIM4 gene) is an actin-associated protein that has previously been shown to stimulate actin bundling by interacting with actin-cross-linking protein α-actinin-1 and increasing its affinity to filamentous actin. Here, we report that the alternatively spliced isoform of RIL, denoted here as RILaltCterm, functions as a dominant-negative modulator of RIL-mediated actin reorganization. RILaltCterm is regulated at the level of protein stability, and this protein isoform accumulates particularly in response to oxidative stress. We show that the alternative C-terminal segment of RILaltCterm has a disordered structure that directs the protein to rapid degradation in the core 20 S proteasomes. Such degradation is ubiquitin-independent and can be blocked by binding to NAD(P)H quinone oxidoreductase NQO1, a detoxifying enzyme induced by prolonged exposure to oxidative stress. We show that either overexpression of RILaltCterm or its stabilization by stresses counteracts the effects produced by full-length RIL on organization of actin cytoskeleton and cell motility. Taken together, the data suggest a mechanism for fine-tuning actin cytoskeleton rearrangement in response to stresses.

Publication types

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

MeSH terms

  • Actinin / genetics
  • Actinin / metabolism
  • Actins / genetics
  • Actins / metabolism*
  • Alternative Splicing*
  • Animals
  • Cytoskeleton / genetics
  • Cytoskeleton / metabolism*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Dogs
  • HeLa Cells
  • Humans
  • LIM Domain Proteins
  • Mice
  • NAD(P)H Dehydrogenase (Quinone) / genetics
  • NAD(P)H Dehydrogenase (Quinone) / metabolism
  • Oxidative Stress*
  • Proteasome Endopeptidase Complex / genetics
  • Proteasome Endopeptidase Complex / metabolism
  • Protein Isoforms / genetics
  • Protein Isoforms / metabolism

Substances

  • ACTN1 protein, human
  • Actins
  • DNA-Binding Proteins
  • LIM Domain Proteins
  • PDLIM4 protein, human
  • Protein Isoforms
  • Actinin
  • NAD(P)H Dehydrogenase (Quinone)
  • NQO1 protein, human
  • Proteasome Endopeptidase Complex