Specific decrease in the level of Hic-5, a focal adhesion protein, during immortalization of mouse embryonic fibroblasts, and its association with focal adhesion kinase.
Hic-5 is a paxillin homologue with four LIM domains in its C-terminal region, localized mainly in focal adhesions in normal fibroblasts. Hic-5 is also known to associate with focal adhesion kinase (FAK) or the related CAKbeta, and with vinculin. In the present study, we examined changes in Hic-5 and paxillin protein levels in primary mouse embryo fibroblasts (MEF) during mortal and immortal stages. The Hic-5 level was markedly decreased when cells became immortalized, whereas that of paxillin was increased. The vinculin level was not changed significantly. Hic-5 was mainly localized in focal adhesion plaques of mortal MEF but was localized in the nuclear periphery in the immortalized MEF; the number of focal adhesion plaques was decreased in these cells. Mouse Hic-5 contains three LD domains in its N-terminal half, and the first LD domain (LD1) appears to be involved in interaction with FAK. However, this interaction was not essential for recruitment of Hic-5 to focal adhesions, since its subcellular localization was similar in FAK(-/-) cells. Forced expression of Hic-5 decreased colony forming ability of MEF from FAK(+/+) mice, but not of FAK(-/-) cells. These observations suggested the involvement of Hic-5 in determination of cellular proliferative capacity in collaboration with other cytoskeletal components.
Ishino
K
K
Department of Microbiology, Showa University School of Pharmaceutical Sciences, Hatanodai, Tokyo, Japan.
Kaneyama
Shibanuma
M
M
Nose
K
K
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D015815:Cell Adhesion Molecules / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002455:Cell Division; D002478:Cells, Cultured; D016922:Cellular Senescence; D003114:Colony-Forming Units Assay; D003598:Cytoskeletal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004622:Embryo, Mammalian; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D060588:LIM Domain Proteins; D051379:Mice; D008969:Molecular Sequence Data; D051419:Paxillin; D010750:Phosphoproteins / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D017384:Sequence Deletion; D016596:Vinculin / Q000378:metabolism
D015815:Cell Adhesion Molecules; D003598:Cytoskeletal Proteins; D017931:DNA Primers; D004268:DNA-Binding Proteins; D060588:LIM Domain Proteins; D051419:Paxillin; D010750:Phosphoproteins; C496062:Pxn protein, mouse; C090090:Tgfb1i1 protein, mouse; D016596:Vinculin; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496051:Ptk2 protein, mouse