title: Uni-axial stretching regulates intracellular localization of Hic-5 expressed in smooth-muscle cells in vivo.
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.
authors.affiliation: Department of Microbiology, Showa University School of Pharmaceutical Sciences, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan.
authors.forename: Joo-ri
authors.initials: JR
authors.lastname: Kim-Kaneyama
authors.forename: Wataru
authors.initials: W
authors.lastname: Suzuki
authors.forename: Kiyoko
authors.initials: K
authors.lastname: Ichikawa
authors.forename: Takahiro
authors.initials: T
authors.lastname: Ohki
authors.forename: Yoko
authors.initials: Y
authors.lastname: Kohno
authors.forename: Masataka
authors.initials: M
authors.lastname: Sata
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Nose
authors.forename: Motoko
authors.initials: M
authors.lastname: Shibanuma
mesh_terms: D000185:Actinin / Q000737:chemistry; D020816:Amino Acid Motifs; D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000378:metabolism; D019556:COS Cells; D002448:Cell Adhesion; D018797:Cell Cycle Proteins / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D003094:Collagen / Q000737:chemistry / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism / Q000502:physiology*; D003599:Cytoskeleton / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000502:physiology*; D005347:Fibroblasts / Q000378:metabolism; D022001:Focal Adhesions / Q000378:metabolism; D020690:GTPase-Activating Proteins; D015151:Immunoblotting; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D060588:LIM Domain Proteins; D051379:Mice; D008813:Mice, Inbred ICR; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D009119:Muscle Contraction; D009130:Muscle, Smooth / Q000166:cytology* / Q000378:metabolism; D051419:Paxillin; D010750:Phosphoproteins / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D013997:Time Factors; D014018:Tissue Distribution; D014162:Transfection
chemical_list: D000911:Antibodies, Monoclonal; D022782:CCAAT-Enhancer-Binding Protein-beta; D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; D020690:GTPase-Activating Proteins; C120766:Git1 protein, mouse; D060588:LIM Domain Proteins; D051419:Paxillin; D010750:Phosphoproteins; C496062:Pxn protein, mouse; C090090:Tgfb1i1 protein, mouse; D000185:Actinin; D003094:Collagen