STUDIES ON THE MECHANISM OF SIGNAL TRANSDUCTION THROUGH HYALURONAN RECEPTORS IN HUMAN SYNOVIAL CELLS OF RHEUMATOID ARTHRITIS.

高分子量醛酸盐（HAs）以分子量和浓度依赖的方式抑制了类风湿性关节炎（RASCs）患者滑膜细胞中自发和il - α诱导的前列腺素E2 （PGE2）的产生。另一方面，分子尺寸小于4x10 ^4 Da的HA，特别是HA低聚物，反而增加了PGE2的生成。HAs对PGE2生成的抑制和刺激作用是由于HA受体的信号事件负或正控制COX2基因的转录。在非炎症细胞，人真皮成纤维细胞（HDF）中，HA低聚物不能诱导COX2蛋白的表达，这表明HA低聚物的作用可能需要某些炎症信号。当从RASC和HDF中分离出ha结合蛋白时，鉴定出了不需要Ca^<2+>和Mg^<2+>来获得ha结合能力的多种膜蛋白。新制备的针对这些ha结合蛋白的单克隆抗体并未抑制COX2蛋白的表达，但部分抗体反而诱导了COX2蛋白在RASC和HDF中的表达。这些结果表明，单个HA分子介导的HA受体交叉连锁的程度可能决定了调节COX2基因转录的细胞内信号的性质。HA寡聚物与单个HA受体分子的结合可能不足以产生诱导COX2蛋白表达的信号。我们没有证据表明细胞内游离钙离子浓度的升高和MAP激酶的激活参与了通过HA受体调控COX2基因转录的信号通路。

The spontaneous and IL-lalpha-induced prostaglandin E2 (PGE2) generation in human synovial cells from a patient of rheumatoid arthritis (RASCs) were inhibited by high-molecular-weighthyaluronates (HAs) in a molecular-weight-and concentration-dependent maimer. On the otherhand, HAs with lower molecular sizes than 4x1O^4 Da, especially HA oligomers, rather augmented PGE2 generation. The inhibitory and stimulatory effects of HAs on PGE2 generation were due to the signaling events via HA receptor that control negatively or positively the transcription of COX2 gene. In noninflammatory cells, human dermal fibroblast (HDF), HA oligomers failed to induce the expression of COX2 protein, suggessting that certain inflammatory signals may be required for the action of HA oligomers. When HA-binding proteins were isolatedfrom RASC and HDF, a various types of membrane proteins that did not required Ca^<2+> and Mg^<2+> for their HA-binding ability were identified. Newly prepared monoclonal antibodies directed to these HA-binding proteins never inhibited the expression of COX2 protein but some of the antibodies rather induced the expression of COX2 protein in RASC and HDF.These results suggest that the extent of cross-linkage of HA receptors that mediated by a single HA molecule may determine the property of intracellular signals that regulate the transcription of COX2 gene. The binding of HA oligomer to a single HA receptor molecule may not be enough to generate signals that may induce the expression of COX2 protein. We could not have a evidence that the elevation of concentration in intracellular free calcium ion and the activation of MAP kinase are involved in the signaling pathway through HA receptors which regulates the transcription of COX2 gene.