Takigawa M, Ishida H, Takano T, Suzuki F
Proc Natl Acad Sci U S A. 1980 Mar;77(3):1481-5. doi: 10.1073/pnas.77.3.1481.
The activity of ornithine decarboxylase (OD-Case:L-ornithine carboxy-lyase, EC 4.1.1.17) in rabbit costal chondrocytes in culture increased markedly after addition of parathyroid hormone (PTH), reaching a maximum 4 to 5 hr after PTH addition. The increase in ODCase activity was followed by increase in the intracellular concentrations of polyamines, especially putrescine, which increased in 6 hr to about 3-fold that of untreated cultures. The induction of ODCase by PTH was not observed in L, 3T3, HeLa, buffalo rat liver, or BHK cells. Retinyl acetate and retinoic acid both inhibited expression of the differentiated phenotype of chondrocytes by rabbit costal chondrocytes in culture within 3 days after their addition, as judged by morphological change and decrease in sulfate incorporation into glycosaminoglycans but did not inhibit cell proliferation. PTH could not induce an increase in ODCase in de-differentiated cells that had been pretreated with retinyl acetate or retinoic acid for 3 days. but 4 days after removal of the retinoids, these de-differentiated cells regained the ability to synthesize ODCase in response to PTH. These facts suggest that the induction of ODCase and the formation of putrescine by PTH are good markers of the differentiated phenotype of cultured chondrocytes.
培养的兔肋软骨细胞中，加入甲状旁腺激素（PTH）后，鸟氨酸脱羧酶（OD - 酶：L - 鸟氨酸羧基裂解酶，EC 4.1.1.17）的活性显著增加，在添加PTH后4至5小时达到最大值。OD - 酶活性增加之后，细胞内多胺浓度升高，尤其是腐胺，在6小时内增加至未处理培养物的约3倍。在L、3T3、HeLa、水牛大鼠肝细胞或BHK细胞中未观察到PTH对OD - 酶的诱导作用。醋酸视黄酯和视黄酸在添加后3天内均抑制培养的兔肋软骨细胞软骨细胞分化表型的表达，这可通过形态变化以及硫酸根掺入糖胺聚糖减少来判断，但不抑制细胞增殖。用醋酸视黄酯或视黄酸预处理3天的去分化细胞中，PTH不能诱导OD - 酶增加。但是在去除类视黄醇4天后，这些去分化细胞恢复了响应PTH合成OD - 酶的能力。这些事实表明，PTH诱导OD - 酶和腐胺形成是培养软骨细胞分化表型的良好标志物。
