蛋白酪氨酸磷酸酶PTP-PEP调节T细胞受体表达及相应机理研究

Protein tyrosine phosphatase PTPN22 was earlier found in mouse cells, named PTP-PEP, and is mainly expressed in T cells. PTP-PEP has been reported to regulate T cell receptor signaling negatively through dephosphorylatng directly or indirectly of Lck, Fyn, ZAP70 and other proteins. The majority of biological functions in regards to PTPN22 were found in mice cell system via the name of PTP-PEP a decade ago. PTP-PEP is called LYP in human species. Recently the biological study is mainly focus on the connections and the mechanism between the LYP single nucleotide polymorphism (SNP) and the resulting autoimmune diseases. However, the biological functions of PTPN22 have not been further analyzed. Recently, our group has successfully created a PTP-PEP CS mice model, in which loss-protein tyrosine phosphatase function of PTP-PEP CS gene was over expressed. By analysis of this mouse model we found that the expression of T cell receptor (TCR) increased significantly. The results suggest that PTP-PEP can regulate TCR expression. We believe that the regulatory mechanisms of TCR is an important scientific problem. Therefore, this project aims to clarify the mechanism of PTP-PEP regulating TCR expression through analyzing the two procedures of endocytosis consumption and newly synthesized TCR transportation. At the same time, we will clarify other effects of PTP-PEP on T cell functions. Ultimately, our studies will have an important impact on the general understanding of T cell functions and the treatment of PTP-PEP induced autoimmune diseases.

蛋白酪氨酸磷酸酶PTPN22（PTP-PEP）早期在小鼠中被发现，主要在T细胞中表达。PTP-PEP可以通过脱磷酸直接或间接调节Lck、Fyn、ZAP70等蛋白来负调控T细胞的信号传导。它的生物功能多数是早期在小鼠系统中发现的。PTP-PEP在人类中称为LYP，近些年主要以单核苷酸多态性(SNP)与自身免疫疾病的相关性及其机理研究。但其它方面的功能没有得到进一步的解析。本课题组最近成功制备了高表达失酶活性PTP-PEP CS的转基因小鼠，并发现T细胞受体（TCR）在细胞膜上表达增加，并且有阴性选择逃逸发生，TCR的调节机制是重要的科学问题。因此，本项目拟从TCR内吞消耗和生成循环途径两方面为切入点，阐明PTP-PEP调节TCR表达能力的机理。同时，探索PTP-PEP调节T细胞的新功能及阐明相应机理。从新视角探讨PTP-PEP对治疗由于T细胞功能缺陷而引起的多种自身免疫性疾病。

蛋白酪氨酸磷酸酶PTPN22（PTP-PEP）早期在小鼠中被发现，主要在T细胞中表达。PTP-PEP可以通过脱磷酸直接或间接调节Lck、Fyn、ZAP70等蛋白来负调控T细胞的信号传导。PTP-PEP在人类中称为LYP，近些年主要集中探讨其单核苷酸多态性诱发多种自身免疫疾病的分子机理。但其它方面的功能没有得到进一步的解析。在本项目中，首先通过制备高表达失酶活性PTP-PEP CS的转基因小鼠模型，克服了PTP-PEP缺陷鼠在六个月龄前没有明显变化的研究难题，为研究PTP-PEP调控T细胞发育等生物功能的机制奠定了研究基础。然后，利用上述全新的动物模型进行初探发现：PTP-PEP CS过表达可调控T细胞受体（TCRmed/hi）在细胞膜上表达显著升高，增强了T细胞的阳性选择，减弱了阴性选择，导致CD4+ T细胞增多。而且，TCR的表达变化主要集中在在CD4+ SP T细胞亚群和CD4+CD8+ DP T细胞亚群中。PTP-PEP CS过表达显著促进了CD3/CD3+CD28抗体的诱导的T细胞增殖功能。TCR的调节机制是重要的科学问题。因此，本项目从TCR膜运输过程入手进行深入探讨，研究发现：在PTP-PEP失去酶活性可造成TCR内在化减弱，再循环增加，导致TCRmed/hi在T细胞表面的积累。为了解析PTP-PEP调控TCR膜运输过程的分子机制，本项目筛选出PTP-PEP新的酶活性底物以及互作蛋白微管结合蛋白EB1与衔接蛋白14-3-3τ。并深入解析了结合位点、酪氨酸磷酸酶活性靶点及PTP-PEP与互作蛋白调控TCR表达等生物功能的分子机制。最后，为了拓展上述成果的应用进一步研究发现，PTP-PEP可能为类风湿关节炎的治疗药物雷公藤甲素的潜在靶点。综上，本项目的相关研究从新视角探索PTP-PEP调节T细胞的新功能及阐明相应机理，为免疫系统相关疾病的诊断、预后提供新的依据。