Leitman D C, Benson S C, Johnson L K
J Cell Biol. 1984 Feb;98(2):541-9. doi: 10.1083/jcb.98.2.541.
The effect of glucocorticoids on collagen synthesis was examined in cultured bovine aortic smooth muscle (BASM) cells. BASM cells treated with 0.1 microM dexamethasone during their proliferative phase (11 d) were labeled with [3H]proline for 24 h, and the acid-precipitable material was incubated with bacterial collagenase. Dexamethasone produced an approximate twofold increase in the incorporation of proline into collagenase-digestible protein (CDP) and noncollagen protein (NCP) in the cell layer and medium. The stimulation was present in both primary mass cultures and cloned BASM. An increase in CDP and NCP was detected at 0.1 nM, while maximal stimulation occurred at 0.1 microM. Only cells exposed to dexamethasone during their log phase of growth (1-6 d after plating) showed the increase in CDP and NCP when labeled 11 d after plating. The stimulatory effect was observed in BASM cells treated with the natural bovine glucocorticoid, cortisol, dexamethasone, and testosterone, but was absent in cells treated with aldosterone, corticosterone, cholesterol, 17 beta-estradiol, and progesterone. The increase in CDP and NCP was absent in cells treated with the inactive glucocorticoid, epicortisol, and totally abolished by the antagonist, 17 alpha-hydroxyprogesterone, suggesting that the response was mediated by specific cytoplasmic glucocorticoid receptors. Dexamethasone-treated BASM cells showed a 4.5-fold increase in the specific activity of intracellular proline, which was the result of a twofold increase in the uptake of proline and depletion of the total proline pool. After normalizing for specific activity, dexamethasone produced a 2.4- and 2.8-fold increase in the rate of collagen and NCP synthesis, respectively. Cells treated with dexamethasone secreted 1.7-fold more collagen protein in 24 h compared to control cultures. The BASM cells secreted 70% Type I and 30% Type III collagen into the media as assessed by two-dimensional gel electrophoresis. The ratio of these two types was not altered by dexamethasone. The results of the present study demonstrate that glucocorticoids can act directly on vascular smooth muscle cells to increase the synthesis and secretion of collagen and NCP.
在培养的牛主动脉平滑肌（BASM）细胞中研究了糖皮质激素对胶原蛋白合成的影响。在增殖期（11天）用0.1微摩尔地塞米松处理的BASM细胞用[3H]脯氨酸标记24小时，然后将酸沉淀物质与细菌胶原酶一起孵育。地塞米松使细胞层和培养基中脯氨酸掺入胶原酶可消化蛋白（CDP）和非胶原蛋白（NCP）的量增加了约两倍。这种刺激在原代大规模培养物和克隆的BASM中均存在。在0.1纳摩尔时检测到CDP和NCP增加，而最大刺激发生在0.1微摩尔时。仅在生长对数期（接种后1 - 6天）暴露于地塞米松的细胞，在接种11天后标记时显示出CDP和NCP增加。在用天然牛糖皮质激素皮质醇、地塞米松和睾酮处理的BASM细胞中观察到刺激作用，但在用醛固酮、皮质酮、胆固醇、17β-雌二醇和孕酮处理的细胞中未观察到。在用无活性糖皮质激素表皮质醇处理的细胞中，CDP和NCP没有增加，并且被拮抗剂17α-羟孕酮完全消除，这表明该反应是由特定的细胞质糖皮质激素受体介导的。用地塞米松处理的BASM细胞内脯氨酸的比活性增加了4.5倍，这是脯氨酸摄取增加两倍和总脯氨酸池耗尽的结果。在标准化比活性后，地塞米松使胶原蛋白和NCP的合成速率分别增加了2.4倍和2.8倍。与对照培养物相比，用地塞米松处理的细胞在24小时内分泌出的胶原蛋白增加了1.7倍。通过二维凝胶电泳评估，BASM细胞向培养基中分泌70%的I型胶原蛋白和30%的III型胶原蛋白。这两种类型的比例未被地塞米松改变。本研究结果表明，糖皮质激素可直接作用于血管平滑肌细胞，增加胶原蛋白和NCP的合成与分泌。
