The focal adhesion scaffold protein Hic-5 regulates vimentin organization in fibroblasts

Mol Biol Cell. 2019 Dec 1;30(25):3037-3056. doi: 10.1091/mbc.E19-08-0442. Epub 2019 Oct 23.

Abstract

Focal adhesion (FA)-stimulated reorganization of the F-actin cytoskeleton regulates cellular size, shape, and mechanical properties. However, FA cross-talk with the intermediate filament cytoskeleton is poorly understood. Genetic ablation of the FA-associated scaffold protein Hic-5 in mouse cancer-associated fibroblasts (CAFs) promoted a dramatic collapse of the vimentin network, which was rescued following EGFP-Hic-5 expression. Vimentin collapse correlated with a loss of detergent-soluble vimentin filament precursors and decreased vimentin S72/S82 phosphorylation. Additionally, fluorescence recovery after photobleaching analysis indicated impaired vimentin dynamics. Microtubule (MT)-associated EB1 tracking and Western blotting of MT posttranslational modifications indicated no change in MT dynamics that could explain the vimentin collapse. However, pharmacological inhibition of the RhoGTPase Cdc42 in Hic-5 knockout CAFs rescued the vimentin collapse, while pan-formin inhibition with SMIFH2 promoted vimentin collapse in Hic-5 heterozygous CAFs. Our results reveal novel regulation of vimentin organization/dynamics by the FA scaffold protein Hic-5 via modulation of RhoGTPases and downstream formin activity.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Actins / metabolism
  • Animals
  • Cell Adhesion / genetics
  • Cells, Cultured
  • Cytoskeletal Proteins / metabolism*
  • Cytoskeleton / metabolism
  • DNA-Binding Proteins / metabolism*
  • Fibroblasts / metabolism
  • Focal Adhesions / metabolism*
  • Humans
  • Intermediate Filaments / metabolism
  • LIM Domain Proteins / metabolism*
  • Mice
  • Mice, Knockout
  • Microtubules / metabolism
  • Phosphorylation
  • Transcription Factors / metabolism
  • Vimentin / metabolism*

Substances

  • Actins
  • Cytoskeletal Proteins
  • DNA-Binding Proteins
  • LIM Domain Proteins
  • Tgfb1i1 protein, mouse
  • Transcription Factors
  • Vimentin