Characterization of catabolin, the major product of pig synovial tissue that induces resorption of cartilage proteoglycan in vitro

Publisher Website
Google Scholar
Abstract
Pig synovium in organ culture produces material which induces living cartilage to resorb its proteoglycan in vitro. The bioassay for this material was to measure glycosaminoglycan released from explants of bovine nasal-septal cartilage cultured for 8 days. The performance of the assay was greatly improved by adding cortisol succinate (0.1 .mu.g/ml). This decreased the release of glycosaminoglycan from unstimulated cartilage without inhibiting its response to catabolic factors from the synovium. By using this improved assay 90% of the active materials in synovial culture medium wre retained by dialysis membrane. An active protein was partially purified from synovial culture medium by (NH4)2SO4 precipitation, ion-exchange chromatography, gel filtration and preparative isoelectric focusing. This protein, called catabolin, had MW 17,000 and pI [isoelectric point] 4.6. Synovial culture medium concentrated in dialysis tubing was subjected to gel chromatography and found to contain 1 major active component, which was eluted at the same position as the partially purified catabolin. The synovial culture medium was not inactivated by heating (70.degree. C for 10 min), nor were diluted preparations of partially purified catabolin, but concentrated crude preparations were thermolabile. Catabolin is apparently the major substance produced by the synovial tissue in culture which induces resorption of proteoglycan of living cartilage in vitro. Other cultured soft connective tissues produced catabolin-like activity. The example of sclera is shown, and production was inhibited by cortisol succinate (0.1 .mu.g/ml). Catabolin may be a general product of soft connective tissues in culture, and its physiological function may be to induce resorption of connective-tissue matrix after injury.

This publication has 21 references indexed in Scilit: