Noda M, Rodan G A
Department of Bone Biology and Osteoporosis Research, Merck Sharp and Dohme Research Laboratories, West Point, Pennsylvania 19486.
J Cell Physiol. 1987 Dec;133(3):426-37. doi: 10.1002/jcp.1041330303.
TGF beta 1 from porcine platelets increased alkaline phosphatase (AP) activity in the rat osteoblastic cell line ROS 17/2.8 about three-fold. This effect was dose-dependent with an ED50 of about approximately 0.2 ng/ml and was larger during logarithmic growth than at confluence. TGF beta 1 inhibited cell growth by about 30% with similar dose dependence. Thirty min exposure to TGF beta 1 was sufficient to increase AP activity 3 days later by about two-fold but did not affect cell growth, suggesting dissociation between effects on proliferation and differentiation. The rise in AP activity started 6 h after TGF beta 1 addition and was blocked by cycloheximide and actinomycin D. TGF beta 1 also increased AP mRNA by two- to three-fold and this effect was not blocked by cycloheximide. The half-life of AP mRNA, estimated following the addition of 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole was about ten h in both control and TGF beta 1-treated cells. The mRNAs for type I procollagen and osteonectin were also increased by TGF beta 1 but fibronectin mRNA was decreased. TGF beta 2 effects on AP and cell growth were similar to those of TGF beta 1, except for lack of activity following transient exposure. At saturating concentrations, TGF beta 2 (2 ng/ml) or dexamethasone (10(-7) M), which has similar effects on these cells, did not further augment the effects of TGF beta 1 (at 2 ng/ml). Above findings suggest that TGF beta promotes osteoblastic differentiation in rat osteosarcoma cells at least in part by acting at the pretranslational level.
来自猪血小板的转化生长因子β1（TGFβ1）可使大鼠成骨细胞系ROS 17/2.8中的碱性磷酸酶（AP）活性增加约三倍。这种效应呈剂量依赖性，半数有效剂量（ED50）约为0.2 ng/ml，且在对数生长期比汇合期的作用更强。TGFβ1以相似的剂量依赖性抑制细胞生长约30%。暴露于TGFβ1 30分钟足以在3天后使AP活性增加约两倍，但不影响细胞生长，这表明其对增殖和分化的影响相互独立。TGFβ1添加后6小时AP活性开始上升，并被环己酰亚胺和放线菌素D阻断。TGFβ1还使AP mRNA增加了两到三倍，且这种效应未被环己酰亚胺阻断。在添加5,6 - 二氯 - 1 - β - D - 呋喃核糖基苯并咪唑后估计，对照细胞和经TGFβ1处理的细胞中AP mRNA的半衰期约为10小时。I型前胶原和骨连接蛋白的mRNA也被TGFβ1增加，但纤连蛋白mRNA减少。TGFβ2对AP和细胞生长的影响与TGFβ1相似，只是短暂暴露后无活性。在饱和浓度下，对这些细胞有类似作用的TGFβ2（2 ng/ml）或地塞米松（10⁻⁷ M）不会进一步增强TGFβ1（2 ng/ml）的作用。上述发现表明，TGFβ至少部分通过在翻译前水平发挥作用来促进大鼠骨肉瘤细胞的成骨细胞分化。
