Uni-axial stretching regulates intracellular localization of Hic-5 expressed in smooth-muscle cells in vivo

J Cell Sci. 2005 Mar 1;118(Pt 5):937-49. doi: 10.1242/jcs.01683. Epub 2005 Feb 15.

Abstract

Hic-5 is a focal adhesion protein belonging to the paxillin LIM family that shuttles in and out of the nucleus. In the present study, we examined the expression of Hic-5 among mouse tissues by immunohistochemistry and found its expression only in smooth-muscle cells in several tissues. This result is consistent with a previous report on adult human tissues and contradicts the relatively ubiquitous expression of paxillin, the protein most homologous to Hic-5. One factor characterizing smooth-muscle cells in vivo is a continuous exposure to mechanical stretching in the organs. To study the involvement of Hic-5 in cellular responses to mechanical stress, we exposed mouse embryo fibroblasts to a uni-axial cyclic stretching and found that Hic-5 was relocalized from focal adhesions to stress fibers through its C-terminal LIM domains during the stress. In sharp contrast to this, paxillin did not change its focal-adhesion-based localization. Of the factors tested, which included interacting partners of Hic-5, only CRP2 (an only-LIM protein expressed in vascular smooth-muscle cells) and GIT1 were, like Hic-5, localized to stress fibers during the cyclic stretching. Interestingly, Hic-5 showed a suppressive effect on the contractile capability of cells embedded in three-dimensional collagen gels, and the effect was further augmented when CRP2 co-localized with Hic-5 to fiber structures of those cells. These results suggested that Hic-5 was a mediator of tensional force, translocating directly from focal adhesions to actin stress fibers upon mechanical stress and regulating the contractile capability of cells in the stress fibers.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actinin / chemistry
  • Amino Acid Motifs
  • Animals
  • Antibodies, Monoclonal / chemistry
  • CCAAT-Enhancer-Binding Protein-beta / metabolism
  • COS Cells
  • Cell Adhesion
  • Cell Cycle Proteins / metabolism
  • Cell Nucleus / metabolism
  • Cells, Cultured
  • Collagen / chemistry
  • Collagen / metabolism
  • Cytoskeletal Proteins / metabolism
  • Cytoskeletal Proteins / physiology*
  • Cytoskeleton / metabolism
  • DNA-Binding Proteins / physiology*
  • Fibroblasts / metabolism
  • Focal Adhesions / metabolism
  • GTPase-Activating Proteins
  • Immunoblotting
  • Immunohistochemistry
  • Immunoprecipitation
  • LIM Domain Proteins
  • Mice
  • Mice, Inbred ICR
  • Microscopy, Electron
  • Microscopy, Fluorescence
  • Muscle Contraction
  • Muscle, Smooth / cytology*
  • Muscle, Smooth / metabolism
  • Paxillin
  • Phosphoproteins / metabolism
  • Plasmids / metabolism
  • Protein Structure, Tertiary
  • Protein Transport
  • Time Factors
  • Tissue Distribution
  • Transfection

Substances

  • Antibodies, Monoclonal
  • CCAAT-Enhancer-Binding Protein-beta
  • Cell Cycle Proteins
  • Cytoskeletal Proteins
  • DNA-Binding Proteins
  • GTPase-Activating Proteins
  • Git1 protein, mouse
  • LIM Domain Proteins
  • Paxillin
  • Phosphoproteins
  • Pxn protein, mouse
  • Tgfb1i1 protein, mouse
  • Actinin
  • Collagen