THROMBOSPONDIN-1 BINDS TO THE SURFACE OF BOVINE ARTICULAR CHONDROCYTES BY A LINEAR RGD-DEPENDENT MECHANISM

Thrombospondin 1 is present in articular cartilage and is synthesized by chondrocytes. Adult bovine articular chondrocytes in serum-free med ium were evaluated in a solid-phase assay for their ability to attach to thrombospondin 1 isolated from human platelets. The chondrocytes at tached to the thrombospondin 1 by a mechanism that was inhibited by a synthetic linear GRGDSP but not a GRGESP peptide, The cells, however, did not spread on thrombospondin 1, but did spread on fibronectin and Pep-Tite 2000, a synthetic RGD-containing peptide, Preincubation of th rombospondin 1 with EDTA irreversibly inhibited its capacity to attach to chondrocytes. We conclude that thrombospondin 1 binds to chondrocy tes by its RGD sequence.