Murrills R J, Stein L S, Horbert W R, Dempster D W
Regional Bone Center, Helen Hayes Hospital, West Haverstraw, New York.
J Bone Miner Res. 1992 Apr;7(4):415-23. doi: 10.1002/jbmr.5650070409.
The role of protein kinase C in the regulation of osteoclast function is not known. We therefore compared the effect of phorbol myristate acetate (PMA), which activates protein kinase C, on the resorptive function, motility, and morphology of osteoclasts from rat and chick. PMA caused a significant reduction in resorption pit number in both species; rat osteoclasts were more sensitive, being significantly inhibited at doses of 10(-9)-10(-6) M compared with 10(-7)-10(-6) M for chick osteoclasts. The inactive analog PMA-alpha was without significant effect, and inhibition was not blocked by 10(-6) M indomethacin. In time course experiments, inhibition at 24 h was similar to or greater than inhibition at 6 h, indicating a persistent or progressive effect on bone resorption. Removal of PMA after 6 h prompted partial recovery of bone-resorptive ability in chick osteoclasts but not rat, at least over a 48 h incubation. In time-lapse video studies of rat osteoclasts, 10(-6) M PMA produced an immediate but transient cessation of motility and retraction of the cell margin into prominent filopodia. Motility resumed within 2.5 h after addition, but the osteoclasts remained partially contracted. Chick osteoclasts behaved similarly but showed no formation of filopodia at the cell periphery and a more rapid recovery of motility than rat osteoclasts; chick osteoclasts also underwent a transient vacuolation following PMA exposure, whereas rat osteoclasts did not. Despite differences in the sensitivity of rat and chick osteoclasts to PMA, these results suggest a fundamental role for protein kinase C in the inhibition of osteoclasts from both species.
蛋白激酶C在破骨细胞功能调节中的作用尚不清楚。因此，我们比较了激活蛋白激酶C的佛波酯（PMA）对大鼠和小鸡破骨细胞的吸收功能、运动性和形态的影响。PMA导致两个物种的吸收陷窝数量显著减少；大鼠破骨细胞更敏感，在10^(-9)-10^(-6) M剂量下受到显著抑制，而小鸡破骨细胞在10^(-7)-10^(-6) M剂量下才受到显著抑制。无活性类似物PMA-α没有显著影响，并且10^(-6) M消炎痛不能阻断这种抑制作用。在时间进程实验中，24小时的抑制作用与6小时的抑制作用相似或更强，表明对骨吸收有持续或渐进的影响。6小时后去除PMA促使小鸡破骨细胞的骨吸收能力部分恢复，但大鼠破骨细胞没有，至少在48小时的孵育过程中是这样。在对大鼠破骨细胞的延时视频研究中，10^(-6) M PMA立即导致运动性短暂停止，细胞边缘回缩形成明显的丝状伪足。添加后2.5小时内运动性恢复，但破骨细胞仍部分收缩。小鸡破骨细胞表现类似，但在细胞周边没有形成丝状伪足，并且运动性恢复比大鼠破骨细胞更快；小鸡破骨细胞在暴露于PMA后还经历了短暂的空泡化，而大鼠破骨细胞没有。尽管大鼠和小鸡破骨细胞对PMA的敏感性存在差异，但这些结果表明蛋白激酶C在抑制这两个物种的破骨细胞方面具有重要作用。
