Transforming growth factor-beta1 regulation of resting zone chondrocytes is mediated by two separate but interacting pathways.
Transforming growth factor-beta1 regulation of resting zone chondrocytes is mediated by two separate but interacting pathways.
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转化生长因子-β1 对静息区软骨细胞的调节是由两条独立但相互作用的途径介导的。
DOI：
10.1016/s0167-4889(00)00030-6
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
Boyan,BD
中科院分区：
文献类型：
--
作者：
Sylvia,VL;Schwartz,Z;Dean,DD;Boyan,BD
以前的研究表明，转化生长因子-β1（TGF-β1）通过一种不依赖于磷脂酶C或酪氨酸激酶的机制刺激蛋白激酶C（PKC），但涉及百日咳毒素敏感的G蛋白。最大激活发生在12小时，需要新的基因表达。为了了解所涉及的信号通路，将静止区软骨细胞与TGF-β1孵育，并用白屈菜红碱、星形孢菌素或H-7抑制PKC活性。[35 S]硫酸盐掺入被抑制，表明PKC介导TGF-β1对基质产生的影响。然而，对[3 H]胸苷掺入的TGF-β1依赖性增加几乎没有影响，TGF-β1刺激的碱性磷酸酶不受影响，表明这些对生长因子的反应不通过PKC调节。TGF-β1引起前列腺素E2（PGE 2）产生的剂量依赖性增加，PKC抑制进一步增加。这种增加受TGF-β1对磷脂酶A2（PLA 2）的依赖性作用调节。激活PLA 2可抑制TGF-β1对PKC的作用，并抑制PLA 2激活的TGF-β1依赖的PKC。外源性花生四烯酸也抑制TGF-β1依赖的PKC增加。TGF-β1对PKC的影响涉及基因组机制，但不涉及现有的膜相关酶的调节，因为没有观察到生长因子对质膜或基质囊泡PKC的直接影响。这些结果支持了TGF-β1通过PKC调节其对基质产生的作用，而其对碱性磷酸酶的作用是通过PGE 2和蛋白激酶A（PKA）的产生来介导的假设。PKA的抑制也降低TGF-β1依赖性增殖。我们先前已经证明，PGE 2通过其EP 2受体刺激碱性磷酸酶，而EP 1信号转导导致PKC减少。因此，在两个路径之间存在串扰。
Previous studies have shown that transforming growth factor-β1 (TGF-β1) stimulates protein kinase C (PKC) via a mechanism that is independent of phospholipase C or tyrosine kinase, but involves a pertussis toxin-sensitive G-protein. Maximal activation occurs at 12 h and requires new gene expression. To understand the signaling pathways involved, resting zone chondrocytes were incubated with TGF-β1 and PKC activity was inhibited with chelerythrine, staurosporine or H-7. [35S]Sulfate incorporation was inhibited, indicating that PKC mediates the effects of TGF-β1 on matrix production. However, there was little, if any, effect on TGF-β1-dependent increases in [3H]thymidine incorporation, and TGF-β1-stimulated alkaline phosphatase was unaffected, indicating that these responses to the growth factor are not regulated via PKC. TGF-β1 caused a dose-dependent increase in prostaglandin E2(PGE2) production which was further increased by PKC inhibition. The increase was regulated by TGF-β1-dependent effects on phospholipase A2(PLA2). Activation of PLA2inhibited TGF-β1 effects on PKC, and inhibition of PLA2activated TGF-β1-dependent PKC. Exogenous arachidonic acid also inhibited TGF-β1-dependent increases in PKC. The effects of TGF-β1 on PKC involve genomic mechanisms, but not regulation of existing membrane-associated enzyme, since no direct effect of the growth factor on plasma membrane or matrix vesicle PKC was observed. These results support the hypothesis that TGF-β1 modulates its effects on matrix production through PKC, but its effects on alkaline phosphatase are mediated by production of PGE2and protein kinase A (PKA). Inhibition of PKA also decreases TGF-β1-dependent proliferation. We have previously shown that PGE2stimulates alkaline phosphatase through its EP2 receptor, whereas EP1 signaling causes a decrease in PKC. Thus, there is cross-talk between the two pathways.