Signal transmission of TGF-beta superfamily in chondrocyte

从关节重建的临床角度，我们研究了如何修复关节表面。关节修复的方法之一是利用培养的软骨细胞进行组织工程修复，而利用培养的软骨细胞修复关节的关键问题是软骨细胞的特性，尤其是软骨细胞的表型。换句话说，希望用过的软骨细胞永远不会骨化。考虑到软骨细胞的这些特点，我们研究了转化生长因子-β超家族在软骨细胞中的信号传递。在本研究中，我们研究了佛波醇，12-肉豆蔻酸酯，13-醋酸酯(PMA)，一种有效和特异的蛋白激酶C(PKC)激活剂和一种有效的非选择性PKC抑制剂对13日龄鸡胚胸骨软骨细胞分化的影响，以及PKC是否在它们的作用中起中介作用。以硫酸蛋白多糖(PG)和I型、II型胶原作为分化标志物。免疫印迹法检测PKC的表达。PMA对软骨形成的抑制作用呈剂量依赖性(1-50 ng/ml)，其作用机制可能与PKC从细胞膜转位到细胞膜有关。星形孢子素促进软骨形成(1-80 nm)，并以剂量依赖的方式引起总PKC的耗竭。一氧化氮合酶(NOS)的特异性抑制剂L精氨酸(NMA)对Stauroporine(4和80 nM)有协同促进PG合成的作用，而对NO的合成则有抑制作用。PMA对PG合成的影响不受NMA的影响。我们认为，NO可能参与了PMA抑制鸡胸骨软骨细胞分化的作用，但斯塔诺孢菌素可能至少部分地通过NO依赖的机制促进了软骨细胞的分化

From a clinical aspect of joint reconstruction, we have investigated how to repair the joint surface. One of the methods to repair the joint is tissue engineering using cultured chondrocytes which has developed markedly.To repair the joint using cultured chondrocytes, important problem is character of chondrocyte, especially their phenotype as articuler chondrocytes. In other words, it is desirable that the used chondrocytes never ossifies. Considering these character of chondrocytes, we investigated signal transmission of TGF-beta superfamily in chondrocytes. In the present study we examined the effect of phorbol, 12-myristate, 13-acetate (PMA), a potent and specific protein kinase C(PKC) activator and Staurosporine, a potent nonselective PKC inhibitor, on the differentiation of sternal chondrocytes from 13-day-old chick embryo, and whether PKC functions as a mediator of their effects. Sulfated proteoglycan (PG) and type I and type II collagen were used as markers of differentiation. PKC expression was assayd by immunoblotting. PMA inhibited chondrogenesis dose-dependently (1-50 ng/ml), and its effects were possibly mediated by the translocation of PKC from the cytozol to the membrane. Staurosporine enhanced chondrogenesis (1-80nM) and caused the depletion of total PKC in a dose-dependent fashion. A synergistic stimulation of PG synthesis by N-monomethyl, L-arginine (NMA), a specific inhibitor of nitric oxide synthase (NOS), in response to Staurosporine (4 and 80 nM), with a corresponding suppression of NO synthesis, has been observed. The effect PMA on PG synthesis was not modulated by NMA.We suggest that NO may no be involved in the inhibition of chick sternal chondrocyte differentiation by PMA,but that Staurosporine may promote chondrogenic differentiation at least in part through a NO-dependent mechanism