Nevo Z, Dorfman A
Proc Natl Acad Sci U S A. 1972 Aug;69(8):2069-72. doi: 10.1073/pnas.69.8.2069.
Chondrocytes in suspension culture preserve their differentiated state, as expressed by a high rate of chondromucoprotein synthesis. Purified chondromuco-protein added to a suspension of cultured embryonic epiphyseal cartilage cells stimulates the rate of synthesis of chondromucoprotein at concentrations up to 2 mg/ml. The stimulation involved synthesis of the entire molecule since incorporation of labeled serine (into core protein), glucosamine, acetate, or sulfate was increased. Neither the amount of synthesis of total protein nor that of collagen was increased. No elevation of xylosyltransferase and N-acetylgalactosaminyltransferase activities was observed. The stimulation was produced by several other polyanionic substances. No evidence was found of the entry of chondromucoprotein into chondrocytes under the conditions of the experiments. Mild trypsinization lowered the response to added chondromucoprotein and decreased the endogenous rate of chondromucoprotein synthesis. Incubation of cells after trypsinization results in restoration of the rates of chondromucoprotein synthesis. The endogenous, as well as the stimulated, rate of chondromucoprotein synthesis varied with the density of chondrocytes in culture. It is suggested that the rate of chondromucoprotein synthesis may be partially controlled by cell surface receptors.
悬浮培养的软骨细胞保持其分化状态，这表现为软骨粘蛋白的高合成率。将纯化的软骨粘蛋白添加到培养的胚胎骨骺软骨细胞悬液中，在浓度高达2mg/ml时可刺激软骨粘蛋白的合成率。这种刺激涉及整个分子的合成，因为标记的丝氨酸（掺入核心蛋白）、氨基葡萄糖、乙酸盐或硫酸盐的掺入量增加。总蛋白和胶原蛋白的合成量均未增加。未观察到木糖基转移酶和N-乙酰半乳糖胺基转移酶活性的升高。其他几种聚阴离子物质也产生了这种刺激。在实验条件下，未发现软骨粘蛋白进入软骨细胞的证据。轻度胰蛋白酶处理降低了对添加的软骨粘蛋白的反应，并降低了软骨粘蛋白的内源性合成率。胰蛋白酶处理后细胞孵育可恢复软骨粘蛋白的合成率。软骨粘蛋白的内源性合成率和受刺激合成率均随培养中软骨细胞的密度而变化。提示软骨粘蛋白的合成率可能部分受细胞表面受体控制。
