title: Hic-5-reduced cell spreading on fibronectin: competitive effects between paxillin and Hic-5 through interaction with focal adhesion kinase.
abstract: Hic-5 is a paxillin homologue that is localized to focal adhesion complexes. Hic-5 and paxillin share structural homology and interacting factors such as focal adhesion kinase (FAK), Pyk2/CAKbeta/RAFTK, and PTP-PEST. Here, we showed that Hic-5 inhibits integrin-mediated cell spreading on fibronectin in a competitive manner with paxillin in NIH 3T3 cells. The overexpression of Hic-5 sequestered FAK from paxillin, reduced tyrosine phosphorylation of paxillin and FAK, and prevented paxillin-Crk complex formation. In addition, Hic-5-mediated inhibition of spreading was not observed in mouse embryo fibroblasts (MEFs) derived from FAK(-/-) mice. The activity of c-Src following fibronectin stimulation was decreased by about 30% in Hic-5-expressing cells, and the effect of Hic-5 was restored by the overexpression of FAK and the constitutively active forms of Rho-family GTPases, Rac1 V12 and Cdc42 V12, but not RhoA V14. These observations suggested that Hic-5 inhibits cell spreading through competition with paxillin for FAK and subsequent prevention of downstream signal transduction. Moreover, expression of antisense Hic-5 increased spreading in primary MEFs. These results suggested that the counterbalance of paxillin and Hic-5 expression may be a novel mechanism regulating integrin-mediated signal transduction.
authors.affiliation: Department of Microbiology, Showa University School of Pharmaceutical Sciences, Hatanodai, Tokyo, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Nishiya
authors.forename: K
authors.initials: K
authors.lastname: Tachibana
authors.forename: M
authors.initials: M
authors.lastname: Shibanuma
authors.forename: J I
authors.initials: JI
authors.lastname: Mashimo
authors.forename: K
authors.initials: K
authors.lastname: Nose
mesh_terms: D016475:3T3 Cells; D000818:Animals; D002448:Cell Adhesion / Q000502:physiology; D003598:Cytoskeletal Proteins / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000502:physiology*; D005353:Fibronectins / Q000502:physiology*; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D005786:Gene Expression Regulation / Q000502:physiology; D060588:LIM Domain Proteins; D051379:Mice; D051419:Paxillin; D010750:Phosphoproteins / Q000502:physiology*; D011505:Protein-Tyrosine Kinases / Q000502:physiology*
chemical_list: D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; D005353:Fibronectins; D060588:LIM Domain Proteins; D051419:Paxillin; D010750:Phosphoproteins; C496062:Pxn protein, mouse; C090090:Tgfb1i1 protein, mouse; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496051:Ptk2 protein, mouse