The PDZ-LIM protein RIL modulates actin stress fiber turnover and enhances the association of alpha-actinin with F-actin

Exp Cell Res. 2004 Feb 1;293(1):117-28. doi: 10.1016/j.yexcr.2003.09.004.


ALP, CLP-36 and RIL form the ALP subfamily of PDZ-LIM proteins. ALP has been implicated in sarcomere function in muscle cells in association with alpha-actinin. The closely related CLP-36 is predominantly expressed in nonmuscle cells, where it localizes to actin stress fibers also in association with alpha-actinin. Here we have studied the expression and functions of RIL originally identified as a gene downregulated in H-ras-transformed cells. RIL was mostly expressed in nonmuscle epithelial cells with a pattern distinct from that of CLP-36. RIL protein was found to localize to actin stress fibers in nonmuscle cells similarly to CLP-36. However, RIL expression led to partially abnormal actin filaments showing thick irregular stress fibers not seen with CLP-36. Furthermore, live cell imaging demonstrated altered stress fiber dynamics with rapid formation of new fibers and frequent collapse of thick irregular fibers in EGFP-RIL-expressing cells. These effects may be mediated through the association of RIL with alpha-actinin, as RIL was found to associate with alpha-actinin via its PDZ domain, and RIL enhanced the ability of alpha-actinin to cosediment with actin filaments. These results implicate the RIL PDZ-LIM protein as a regulator of actin stress fiber turnover.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actinin / metabolism*
  • Actins / metabolism*
  • Animals
  • Cell Line, Tumor
  • Cells, Cultured
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Epithelial Cells / metabolism*
  • Fibroblasts / metabolism*
  • Gene Expression
  • Glutathione Transferase / metabolism
  • Green Fluorescent Proteins
  • Homeodomain Proteins / metabolism
  • Humans
  • LIM Domain Proteins
  • Luminescent Proteins / metabolism
  • Osteosarcoma / genetics
  • Osteosarcoma / metabolism
  • Osteosarcoma / pathology
  • Rats
  • Recombinant Proteins / metabolism
  • Time Factors
  • Zinc Fingers


  • Actins
  • DNA-Binding Proteins
  • Homeodomain Proteins
  • LIM Domain Proteins
  • Luminescent Proteins
  • PDLIM4 protein, human
  • Pdlim1 protein, rat
  • Pdlim4 protein, rat
  • Recombinant Proteins
  • Actinin
  • Green Fluorescent Proteins
  • Glutathione Transferase