Implication of transcriptional coactivator complexes in rheumatoid synovial cells

为了评估转录辅活化子在类风湿滑膜细胞激活中的意义，我们尝试了以下两种方法。一个是对核乙酰化的评价，它是CREB结合蛋白(CBP)共激活功能的关键作用之一。另一种是利用酵母双杂交系统克隆类风湿滑膜细胞中的CBP相互作用蛋白。1)利用乙酰化赖氨酸的特异性抗体，我们在类风湿滑膜细胞中检测到有效的核乙酰化，揭示了P53是一种特征性的乙酰化蛋白。我们进一步发现，肿瘤坏死因子α诱导了滑膜细胞中P53的乙酰化，但减弱了其转录激活。由于CBP的过表达导致肿瘤坏死因子α激活P53启动子，因此P53的激活需要CBP的募集。2)我们从类风湿滑膜细胞的文库中克隆了CBP结合蛋白Notch-1。Notch-1信号通过肿瘤坏死因子α信号在类风湿滑膜细胞中特异性地激活，并通过肿瘤坏死因子α参与了滑膜细胞的增殖。

To assess the implication of transcriptional coactivator in rheumatoid synoviocytes activation, we attempted the following two approaches. One is evaluation of nuclear acetylation, one of the critical roles as coactivator function of CREB binding protein (CBP). The other is molecular cloning of CBP-interaction proteins in rheumatoid synoviocytes by yeast two-hybrid systems.1) Using a specific antibody against acetylated lysine, we detected potent nuclear acetylation in rheumatoid synoviocytes and revealed that p53 is one of characteristically acetylated proteins. We further found that TNFα induced acetylation of p53 but attenuated its transcriptional activation in synoviocytes. As overexpression of CBP resulted in p53 promoter activation by TNFα, CBP recruitment is required for p53 activation.2) We cloned Notch-1 as one of CBP-binding proteins from cDNA library prepared from rheumatoid synoviocytes. Notch-1 signal was characteristically activated in rheumatoid synoviocytes though TNFα signaling and implicated in synoviocytes proliferation by TNFα.These results clearly suggested that coactivator takes crucial roles for rheumatoid synoviocytes activation and might contribute to clarifying the pathogenesis of RA.