Sandy J D, Brown H L, Lowther D A
Biochem J. 1980 Apr 15;188(1):119-30. doi: 10.1042/bj1880119.
When slices of adult rabbit articular cartilage were incubated in culture medium, the rate of incorporation of [35S]sulphate or [3H]acetate into glycosaminoglycans increased 4-8 fold during the first 5 days of incubation. Similar changes in biosynthetic activity were observed during culture of adult bovine cartilage. The activation of synthesis was not serum-dependent, but appeared to be a result of the depletion of tissue proteoglycan that occurs under these incubation conditions [Sandy, Brown & Lowther (1978) Biochim. Biophys. Acta 543, 536--544]. Thus, although complete activation was observed in serum-free medium, it was not observed if the cartilage was cultured inside dialysis tubing or in medium containing added proteoglycan subunit. The average molecular size of the proteoglycans synthesized by activated tissue was slightly larger than normal, as determined by chromatography on Sepharose CL-2B, and the average molecular size of the glycosaminoglycans synthesized by activated tissue was markedly increased over the normal. The increase in chain size was accompanied by an increase in the proportion of the chains degraded by chondroitinase ABC; these results are consistent with the preferential synthesis by activated chondrocytes of chondroitin sulphate-rich proteoglycans. The increase in glycosaminoglycan chain size was observed whether the chains were formed on endogenous core protein or on exogenous benzyl-beta-D-zyloside. An approximate 4-fold activation in culture of glycosaminoglycan synthesis on protein core was accompanied by a 1.54-fold increase in the rate of incorporation of [3H]serine into the chondroitin sulphate-linkage region of the proteoglycans. A 2.8-fold activation in culture of glycosaminoglycan synthesis on benzyl-beta-D-zyloside was accompanied by a 1.7-fold increase in the rate of incorporation of [3H]benzyl-beta-D-zyloside into glycosaminoglycans. The activation of glycosaminoglycan synthesis was, however, accompanied by no detectable change in the activity of xylosyltransferase (EC 2.4.2.26) in cell-free extracts. These results are discussed in relation to current ideas on the control of proteoglycan synthesis in cartilage.
将成年兔关节软骨切片置于培养基中培养时，在培养的前5天，[35S]硫酸盐或[3H]乙酸盐掺入糖胺聚糖的速率增加了4至8倍。在成年牛软骨培养过程中也观察到了生物合成活性的类似变化。合成的激活不依赖于血清，而似乎是这些培养条件下组织蛋白聚糖耗竭的结果[Sandy, Brown & Lowther (1978) Biochim. Biophys. Acta 543, 536 - 544]。因此，虽然在无血清培养基中观察到了完全激活，但如果软骨在透析管内培养或在添加了蛋白聚糖亚基的培养基中培养，则未观察到激活。通过琼脂糖CL - 2B柱层析测定，激活组织合成的蛋白聚糖的平均分子大小略大于正常情况，激活组织合成的糖胺聚糖的平均分子大小比正常情况显著增加。链大小的增加伴随着硫酸软骨素酶ABC降解的链的比例增加；这些结果与激活的软骨细胞优先合成富含硫酸软骨素的蛋白聚糖一致。无论链是在内源性核心蛋白上形成还是在外源性苄基 - β - D - 木糖苷上形成，都观察到了糖胺聚糖链大小的增加。蛋白核心上糖胺聚糖合成培养中约4倍的激活伴随着[3H]丝氨酸掺入蛋白聚糖硫酸软骨素连接区域的速率增加1.54倍。苄基 - β - D - 木糖苷上糖胺聚糖合成培养中2.8倍的激活伴随着[3H]苄基 - β - D - 木糖苷掺入糖胺聚糖的速率增加1.7倍。然而，糖胺聚糖合成的激活伴随着无细胞提取物中木糖基转移酶（EC 2.4.2.26）活性没有可检测到的变化。结合当前关于软骨中蛋白聚糖合成控制的观点对这些结果进行了讨论。
