α-Actinin-4 enhances colorectal cancer cell invasion by suppressing focal adhesion maturation

PLoS One. 2015 Apr 10;10(4):e0120616. doi: 10.1371/journal.pone.0120616. eCollection 2015.

Abstract

α-Actinins (ACTNs) are known to crosslink actin filaments at focal adhesions in migrating cells. Among the four isoforms of mammalian ACTNs, ACTN1 and ACTN4 are ubiquitously expressed. Recently, ACTN4 was reported to enhance cancer cell motility, invasion, and metastasis. However, the mechanism by which ACTN4 drives these malignant phenotypes remains unclear. Here, we show that ACTN4, but not ACTN1, induces the formation of immature focal adhesions in DLD-1 cells, leading to the rapid turnover of focal adhesions. Interestingly, zyxin (ZYX) assembly to focal adhesions was markedly decreased in ACTN4-expressing DLD-1 cells, while the recruitment of paxillin (PAX) occurred normally. On the other hand, in ACTN1-expressing DLD-1 cells, PAX and ZYX were normally recruited to focal adhesions, suggesting that ACTN4 specifically impairs focal adhesion maturation by inhibiting the recruitment of ZYX to focal complexes. Using purified recombinant proteins, we found that ZYX binding to ACTN4 was defective under conditions where ZYX binding to ACTN1 was observed. Furthermore, Matrigel invasion of SW480 cells that express high endogenous levels of ACTN4 protein was inhibited by ectopic expression of ACTN1. Altogether, our results suggest that ZYX defective binding to ACTN4, which occupies focal adhesions instead of ACTN1, induces the formation of immature focal adhesions, resulting in the enhancement of cell motility and invasion.

MeSH terms

  • Actinin / antagonists & inhibitors
  • Actinin / genetics
  • Actinin / metabolism*
  • Caco-2 Cells
  • Cell Line, Tumor
  • Cell Movement
  • Colorectal Neoplasms / metabolism
  • Colorectal Neoplasms / pathology
  • Focal Adhesions / metabolism*
  • HT29 Cells
  • Humans
  • Microscopy, Fluorescence
  • Neoplasm Invasiveness
  • Paxillin / metabolism
  • Protein Binding
  • RNA Interference
  • RNA, Small Interfering / metabolism
  • Recombinant Proteins / biosynthesis
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / isolation & purification
  • Zyxin / chemistry
  • Zyxin / genetics
  • Zyxin / metabolism

Substances

  • ACTN1 protein, human
  • ACTN4 protein, human
  • Paxillin
  • RNA, Small Interfering
  • Recombinant Proteins
  • ZYX protein, human
  • Zyxin
  • Actinin

Grants and funding

This work was supported by Japan Society for the Promotion of Science (JSPS) through JSPS Grants-in-Aid for Scientific Research Grant 25860215 (to S. Kurisu) and JSPS Grants-in-Aid for Scientific Research Grant 23227005 (to T. Takenawa). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.