Cell-substratum interaction of cultured avian osteoclasts is mediated by specific adhesion structures.
The cell-substratum interaction was studied in cultures of osteoclasts isolated from the medullary bone of laying hens kept on low calcium diet. In fully spread osteoclasts, cell-substratum adhesion mostly occurred within a continuous paramarginal area that corresponded also to the location of a thick network of intermediate filaments of the vimentin type. In this area, regular rows of short protrusions contacting the substratum and often forming a cup-shaped adhesion area were observed in the electron microscope. These short protrusions showed a core of F-actin-containing material presumably organized as a network of microfilaments and surrounded by a rosette-like structure in which vinculin and alpha-actinin were found by immunofluorescence microscopy. Rosettes were superposable to dark circles in interference-reflection microscopy and thus represented circular forms of close cell-substratum contact. The core of ventral protrusions also contained, beside F-actin, fimbrin and alpha-actinin. Villin was absent. This form of cell-substratum contact occurring at the tip of a short ventral protrusion differed from other forms of cell-substratum contact and represented an osteoclast-specific adhesion device that might also be present in in vivo osteoclasts as well as in other normal and transformed cell types.
D000185:Actinin / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D000818:Animals; D002448:Cell Adhesion; D002478:Cells, Cultured; D002645:Chickens; D005260:Female; D005455:Fluorescent Antibody Technique; D006651:Histocytochemistry; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000378:metabolism; D008840:Microfilament Proteins; D008854:Microscopy, Electron; D009124:Muscle Proteins / Q000378:metabolism; D010010:Osteoclasts / Q000378:metabolism / Q000648:ultrastructure*; D016596:Vinculin
D000199:Actins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D008840:Microfilament Proteins; D009124:Muscle Proteins; C026742:plastin; D000185:Actinin; D016596:Vinculin