The role of the RNA binding protein KSRP in pro-inflammatory gene expression

人类慢性炎症性疾病，如类风湿性关节炎(RA)、系统性红斑狼疮(SLE)、哮喘、糖尿病或动脉粥样硬化，其特点是致炎基因表达异常。这些基因的表达主要是在转录后水平上调节的。位于这些mRNAs的3‘-非翻译区的富Au元素在这些过程中起着中心作用。RNA结合蛋白(RNA-BP)与这些序列元件结合，调节mRNAs的稳定性、可译性和定位。我们证明了KSRP在人类诱导型一氧化氮合酶的转录后表达调控中起主要作用。在上一个资助阶段，我们在人类软骨细胞中发现了一些慢性炎症性疾病的介质(如MMP3、MMP9、RANTES)作为新的KSRP靶向mRNAs。在胶原性关节炎模型(CIA，RA模型)和MRL-FASlpr小鼠模型(SLE模型)中，我们检测到KSRP的表达与促炎基因的表达呈负相关，同时，我们建立了本实验室培育的KSRP基因失活小鼠(KSRP-/-小鼠，来自陈博士)。在这些小鼠中，我们在体内和在原代细胞中证实了KSRP介导的IL-8-、iNOS和TNF-α表达的调节。分子分析表明，KSRP在人类细胞中的表达是自动调节的。我们小组最近的工作表明，白藜芦醇的抗炎作用可以通过这种植物抗毒素与KSRP的直接结合来解释。这种相互作用导致了KSRP蛋白活性的增强。在下一个资金阶段，我们希望通过KSRP-/--小鼠模型在体内检测KSRP表达变化在慢性炎症性疾病中的作用。为了分析KSRP基因失活对疾病进展和严重程度的影响，我们将在这些小鼠中建立CIA和SLE模型。在这些模型中，我们将研究KSRP在免疫过程中的作用。此外，我们希望在体内分析白藜芦醇是否通过调节KSRP活性来发挥其抗炎作用。计划中的项目的另一个重点是了解KSRP在慢性炎症性疾病中表达的分子机制。此外，在RA和SLE患者的血细胞中，我们想要确定在我们的体外和动物模型中获得的结果是否可以转化到人类系统中。

Human chronic inflammatory diseases such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), asthma, diabetes or atherosclerosis are characterized by a dysregulated expression of pro-inflammatory genes. The expression of these genes is regulated on the post-transcriptional level, primarily. AU-rich elements located in the 3'-untranslated region of those mRNAs are centrally involved in these processes. RNA binding proteins (RNA-BP) bind to these sequence elements and modulate stability, translatability and localization of the mRNAs. We demonstrated that KSRP plays a major role in the post-transcriptional regulation of the expression of the pro-inflammatory enzyme human inducible NO synthase.In the last funding period we identified in human chondrocytes several mediators of chronic inflammatory diseases (like MMP3, MMP9, RANTES) as new KSRP-target mRNAs. In the model of collagen-induced arthritis (CIA, RA model) and in MRL-FASlpr mice (SLE model) we detected a negative correlation between the expression of KSRP and pro-inflammatory genes.Meanwhile, we established the breeding of mice with inactivated KSRP gene (KSRP-/--mice, obtained from Dr. Chen) in our lab. In these mice we confirmed in-vivo and in primary cells the KSRP-mediated regulation of IL-8-, iNOS and TNF-alpha expression. Molecular analyses showed an autoregulation of KSRP expression in human cells. Recent work of our group indicated that the anti-inflammatory effects of resveratrol could be explained by a direct binding of this phytoalexin to KSRP. This interaction resulted in enhanced activity of the KSRP protein.In the next funding period we want to examine the effects of altered KSRP expression in chronic inflammatory diseases in vivo using the KSRP-/--mice model. To analyze the effects of inactivation of the KSRP gene on disease progression and severity we will establish CIA and SLE models in those mice. In these models we will study the role of KSRP in immunological processes. In addition we want to analyze in-vivo whether resveratrol performs its anti-inflammatory effects via modulation of KSRP activity. Another focus of the planned project is to understand the molecular mechanisms regulating the expression of KSRP in chronic inflammatory diseases. Moreover in blood cells from RA and SLE patients we want to determine whether the results obtained in our in-vitro and animal models could be translated to the human system.