Chondrocyte aggregation in suspension culture is GFOGER-GPP- and beta1 integrin-dependent.
Isolated chondrocytes form aggregates in suspension culture that maintain chondrocyte phenotype in a physiological pericellular environment. The molecular mechanisms involved in chondrocyte aggregation have not been previously identified. Using this novel suspension culture system, we performed mRNA and protein expression analysis along with immunohistochemistry for potential cell adhesion molecules and extracellular matrix integrin ligands. Inhibition of aggregation assays were performed using specific blocking agents. We found that: (i) direct cell-cell interactions were not involved in chondrocyte aggregation, (ii) chondrocytes in aggregates were surrounded by a matrix rich in collagen II and cartilage oligomeric protein (COMP), (iii) aggregation depends on a beta1-integrin, which binds a triple helical GFOGER sequence found in collagens, (iv) integrin alpha10-subunit is the most highly expressed alpha-subunit among those tested, including alpha5, in aggregating chondrocytes. Taken together, this body of evidence suggests that the main molecular interaction involved in aggregation of phenotypically stable chondrocytes is the alpha10beta1-collagen II interaction.
Gigout
Anne
A
Department of Chemical Engineering, Ecole Polytechnique, Montreal, Quebec H3C 3A7, Canada.
Jolicoeur
Mario
M
Nelea
Monica
M
Raynal
Nicolas
N
Farndale
Richard
R
Buschmann
Michael D
MD
D000595:Amino Acid Sequence; D000818:Animals; D015820:Cadherins / Q000378:metabolism; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D002417:Cattle; D002449:Cell Aggregation; D018929:Cell Culture Techniques / Q000379:methods*; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology* / Q000378:metabolism* / Q000648:ultrastructure; D003094:Collagen / Q000737:chemistry / Q000378:metabolism*; D019012:Integrin beta1 / Q000378:metabolism*; D007477:Ions / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D019006:Neural Cell Adhesion Molecules / Q000378:metabolism; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism*; D010641:Phenotype; D017433:Protein Structure, Secondary; D021122:Protein Subunits / Q000378:metabolism; D012685:Sepharose; D019699:Thrombospondins / Q000378:metabolism
D015820:Cadherins; D019012:Integrin beta1; D007477:Ions; D019006:Neural Cell Adhesion Molecules; D010446:Peptide Fragments; D021122:Protein Subunits; D019699:Thrombospondins; D003094:Collagen; D012685:Sepharose; D002118:Calcium