Cartilage fibrils of mammals are biochemically heterogeneous: Differential distribution of decorin and collagen IX
Cartilage fibrils of mammals are biochemically heterogeneous: Differential distribution of decorin and collagen IX
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DOI：
10.1083/jcb.142.1.285
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发表时间：
1998-07-13
影响因子：
7.8
通讯作者：
Hedbom, E
中科院分区：
文献类型：
--
作者：
Hagg, R;Bruckner, P;Hedbom, E
软骨原纤维以II型胶原蛋白为主要成分，但其他成分、少量胶原蛋白和非胶原糖蛋白的存在被认为对调节软骨原纤维的一些特性至关重要。我们检查了两种纤维成分的分布-decorin和胶原ix -在牛软骨均质后获得的纤维碎片样品中。Decorin优先与来自成人关节软骨的较厚纤维碎片相关，但不存在于最薄的原纤维上。这种结合对原纤维的间隙区有特异性，并且依赖于decorin核心蛋白。相比之下，胶原IX在最薄的原纤维中占主导地位，在较宽的原纤维中很少出现。双标记实验表明，在一些中等直径的原纤维中，decorin和胶原IX共存，尽管大多数来自成人软骨的原纤维片段对其中一种成分强烈阳性，而缺乏另一种成分。来自胎儿骺软骨的纤维碎片显示出不同的模式，在中、大直径的碎片上经常出现decorin和胶原DL。因此，胶原IX的存在并不仅限于小直径的原纤维。这些结果证实关节软骨原纤维具有生物化学异质性。不同种群的原纤维共享胶原II，但在大分子方面具有不同的组成，这决定了它们的表面性质。
Cartilage fibrils contain collagen II as the major constituent, but the presence of additional components, minor collagens, and noncollagenous glycoproteins is thought to be crucial for modulating several fibril properties. We have examined the distribution of two fibril constituents-decorin and collagen IX-in samples of fibril fragments obtained after bovine cartilage homogenization. Decorin was preferentially associated with a population of thicker fibril fragments from adult articular cartilage, but was not present on the thinnest fibrils. The binding was specific for the gap regions of the fibrils, and depended on the decorin core protein. Collagen IX, by contrast, predominated in the population with the thinnest fibrils, and was scarce on wider fibrils. Double-labeling experiments demonstrated the coexistence of decorin and collagen IX in some fibrils of intermediate diameter, although most fibril fragments from adult cartilage were strongly positive for one component and lacked the other. Fibril fragments from fetal epiphyseal cartilage showed a different pattern, with decorin and collagen DL frequently colocalized on fragments of intermediate and large diameters. Hence, the presence of collagen IX was not exclusive for fibrils of small diameter. These results establish that articular cartilage fibrils are biochemically heterogeneous. Different populations of fibrils share collagen II, but have distinct compositions with respect to macromolecules defining their surface properties.