Johnson Anna, Smith Roger, Saxne Tore, Hickery Mark, Heinegård Dick
Department of Cell and Molecular Biology, Section for Connective Tissue Biology, Lund University, Lund, Sweden.
Osteoarthritis Cartilage. 2004 Feb;12(2):149-59. doi: 10.1016/j.joca.2003.10.008.
Previous experiments have shown that addition of fragmented fibronectin can induce cartilage chondrolysis. In this study we investigated the fate of the collagen- and cell-binding molecules Cartilage oligomeric matrix protein (COMP) and chondroadherin.
Equine articular cartilage explants were stimulated with the C-terminal and the N-terminal heparin-binding fragments of fibronectin respectively, and the conditioned media were analysed by both quantitative (ELISA) and qualitative (mass spectrometry, Western blots) methods.
Both COMP and chondroadherin were released in a dose-dependent manner upon stimulation with the Hep II (C-terminal heparin-binding) fragment of fibronectin. The kinetics of release for the two components differed. Moreover, COMP was degraded while no fragments of chondroadherin could be detected. Stimulation with Hep II also induced production of nitric oxide in a dose-dependent manner. We compared effects of the Hep II fragment with that of Hep I (the N-terminal heparin-binding fragment of fibronectin) and found that while Hep I did indeed elicit release of COMP and chondroadherin, the response was less potent, and production of nitric oxide was negligible. The responses to both fragments were elicited within 24h.
We suggest that the events described here may be early, critical stages in cartilage destruction preceding collagen destruction.
先前的实验表明，添加片段化纤连蛋白可诱导软骨溶解。在本研究中，我们调查了胶原蛋白结合分子和细胞结合分子软骨寡聚基质蛋白（COMP）及软骨粘连蛋白的去向。
分别用纤连蛋白的C端和N端肝素结合片段刺激马关节软骨外植体，并用定量（酶联免疫吸附测定）和定性（质谱、蛋白质免疫印迹）方法分析条件培养基。
在用纤连蛋白的Hep II（C端肝素结合）片段刺激后，COMP和软骨粘连蛋白均呈剂量依赖性释放。两种成分的释放动力学不同。此外，COMP被降解，而未检测到软骨粘连蛋白的片段。用Hep II刺激也以剂量依赖性方式诱导一氧化氮的产生。我们比较了Hep II片段与Hep I（纤连蛋白的N端肝素结合片段）的作用，发现虽然Hep I确实引起了COMP和软骨粘连蛋白的释放，但反应较弱，且一氧化氮的产生可忽略不计。对两种片段的反应均在24小时内引发。
我们认为，此处描述的事件可能是软骨破坏中先于胶原蛋白破坏的早期关键阶段。
