Ng C K, Handley C J, Preston B N, Robinson H C, Bolis S, Parker G
Department of Biochemistry, Monash University, Clayton, Victoria, Australia.
Arch Biochem Biophys. 1995 Jan 10;316(1):596-606. doi: 10.1006/abbi.1995.1079.
The addition of hyaluronan to the culture medium of explant cultures of articular cartilage was shown to suppress the synthesis of hyaluronan and aggrecan, the major proteoglycan present in cartilage, and resulted in a greater proportion of the newly synthesized aggrecan and hyaluronan appearing in the culture medium. This effect of exogenous hyaluronan on aggrecan and hyaluronan synthesis was concentration-dependent and reversible on removal of the glycosaminoglycan from the culture medium. The addition of tetra- and hexasaccharides derived from Streptomyces sp. hyaluronidase digestion of hyaluronan to explant cultures of articular cartilage did not change the rate of synthesis of aggrecan or hyaluronan or their ultimate distribution between tissue and medium. However, the addition of tetra- and hexasaccharides of hyaluronan resulted in a decrease in the rate of loss of hyaluronan from the tissue but not that of aggrecan, which remained the same as in control cultures. This suppression of the rate of loss of hyaluronan was eliminated on removal of the hyaluronan oligosaccharides from the culture medium. Analysis of the hydrodynamic size of the newly synthesized hyaluronan indicated that the presence of hyaluronan tetra- and hexasaccharides brought about an accumulation of hyaluronan of intermediate molecular mass. Since no radiolabeled hyaluronan was detected in the culture medium, it was concluded that the tetra- and hexasaccharides inhibited the internalization and intracellular catabolism of hyaluronan by the cartilage explant cultures. Regardless of whether hyaluronan or tetra- and hexasaccharides of hyaluronan were added to the culture medium, newly synthesized hyaluronan underwent depolymerization at a rate consistent with a mechanism involving oxygen-derived radicals.
研究表明，向关节软骨外植体培养物的培养基中添加透明质酸会抑制透明质酸和聚集蛋白聚糖（软骨中存在的主要蛋白聚糖）的合成，导致新合成的聚集蛋白聚糖和透明质酸在培养基中出现的比例更高。外源性透明质酸对聚集蛋白聚糖和透明质酸合成的这种作用具有浓度依赖性，并且在从培养基中去除糖胺聚糖后是可逆的。将来源于链霉菌透明质酸酶消化透明质酸的四糖和六糖添加到关节软骨外植体培养物中，不会改变聚集蛋白聚糖或透明质酸的合成速率，也不会改变它们在组织和培养基之间的最终分布。然而，添加透明质酸的四糖和六糖会导致透明质酸从组织中流失的速率降低，但聚集蛋白聚糖的流失速率不变，与对照培养物中的情况相同。在从培养基中去除透明质酸寡糖后，这种对透明质酸流失速率的抑制作用就会消除。对新合成的透明质酸的流体力学尺寸分析表明，透明质酸四糖和六糖的存在导致中等分子量透明质酸的积累。由于在培养基中未检测到放射性标记的透明质酸，因此得出结论，四糖和六糖抑制了软骨外植体培养物对透明质酸的内化和细胞内分解代谢。无论向培养基中添加透明质酸还是透明质酸的四糖和六糖，新合成的透明质酸都会以与涉及氧衍生自由基的机制一致的速率发生解聚。
