Expression and function of discoidin domain receptor 1 in T cells

为了有效的免疫应答和到达靶组织，激活/效应T细胞必须克服血管以及基底膜和间质基质的细胞外基质(ECM)的屏障，这些屏障主要由胶原组成。使用三维(3D)模型，如胶原胶，发现激活的T细胞利用变形虫运动独立于强大的粘附力和整合素迁移到胶原蛋白中。在这方面，我们和其他人以前报道过，盘状结构域受体1(DDR1)是一种结合胶原蛋白的酪氨酸激酶受体，在T细胞激活过程中被诱导，并参与激活的人T细胞在3D胶原中的迁移。我们最近证实，绝大多数人Th17细胞表达DDR1，但不表达DDR2，并且沉默DDR1或使用阻断的重组受体(DDR1：Fc)显著减少它们在3D胶原中的迁移。DDR1通过激活RhoA/ROCK/MAPK/ERK信号轴促进Th17细胞的阿米巴运动。最后，我们证明了DDR1对于Th17细胞在体内(小鼠气囊模型)的募集是重要的。效应性T细胞在血管周围组织中的迁移机制尚不清楚。因此，根据我们的研究，我们认为DDR1可能是T细胞迁移和免疫反应发展的主要受体。目的I：DDR1在T细胞亚群中的表达和功能：为了进一步探讨DDR1在免疫应答中的作用，我们将检测其在人T细胞亚群中的表达和迁移功能，包括Th1、Th2和Th17以及Tc1、Tc2和Tc17。体外和体外极化的T细胞亚群都将被描述。*目的II：DDR1在T细胞存活和信号中的作用：除了促进细胞运动外，DDR1还可以促进T细胞在3D胶原蛋白中的存活。因此，我们将通过确定DDR1在调节3D胶原中T细胞凋亡以及在调节促和抗凋亡的Bcl-2蛋白中的作用来评估这种可能性。我们还将研究MAPK、PI3激酶/AKT和JAK/STAT通路在DDR1介导的T细胞存活和肌动球蛋白收缩中的作用，并定义DDR1相互作用的蛋白。*目的III：DDR1在保护性免疫中的作用：为了进一步探讨DDR1在体内和免疫反应发展中的作用，我们将利用DDR1 KO小鼠和裸鼠T细胞转移实验来研究DDR1在抗微生物免疫(肺炎链球菌感染的小鼠模型)中的作用。*意义：这些研究将对T细胞在血管周围组织中迁移的机制以及宿主防御和保护性免疫的机制带来新的见解和理解。由于细胞迁移是一个由所有有核细胞执行的过程，我们相信我们的研究将对理解形态发生和组织再生等其他过程产生重大影响。

For an effective immune response and to reach target tissues, activated/effector T cells must overcome the barriers of the blood vessels as well as the extracellular matrix (ECM) of the basement membrane and of the interstitial stroma, which is constituted mainly of collagen. The use of three-dimensional (3D) models such as collagen gels revealed that activated T cells use the amoeboid movement to migrate in collagen independently from strong adhesive forces and integrins. In this regard, we and others previously reported that the discoidin domain receptor 1 (DDR1), a tyrosine kinase receptor, which binds collagens, is induced during T cell activation and participates in the migration of activated human T cells in 3D collagen. We recently demonstrated that the vast majority of human Th17 cells express DDR1 but not DDR2 and that silencing DDR1 or using the blocking recombinant receptor (DDR1:Fc) significantly reduced their migration in 3D collagen. DDR1 promoted amoeboid movement of Th17 cells by activating the RhoA/ROCK/MAPK/ERK signaling axis. Finally, we showed that DDR1 is important for the recruitment of Th17 cells in vivo (mouse air pouch model). The mechanisms of effector T cell migration in perivascular tissues are still poorly understood. Thus, based on our studies, we propose that DDR1 can be a major receptor in T cell migration and in the development of immune response. ***Aim I: DDR1 expression and function in T cell subsets: To further explore the role of DDR1 in immune response, we will examine its expression and migratory function in human T cell subsets including Th1, Th2 and Th17 and Tc1, Tc2 and Tc17. Both ex-vivo and in vitro polarized T cell subsets will be characterized.***Aim II: DDR1 in T cell survival and signaling: In addition of promoting cell movement, DDR1 can also favour T cell survival in 3D collagen. Thus, we will assess this possibility by determining the role of DDR1 in the regulation of T cell apoptosis in 3D collagen and in the regulation of pro- and anti-apoptotic Bcl-2 proteins. We will also examine the implication of MAPK, PI3 kinase/AKT and JAK/STAT pathways in DDR1-mediated T cell survival and in actomyosin contraction and we will define the DDR1-interacting proteins.***Aim III: Role of DDR1 in protective immunity: To further explore the role of DDR1 in vivo and in the development of immune response, we will examine the role of DDR1 in anti-microbial immunity (mouse model of S. Pneumoniae infection) using the DDR1 KO mice and T cell transfer experiments in nude mice. ***Significance: These studies will bring new insights and understanding of the mechanisms involved in T cell migration in perivascular tissues and consequently in the mechanisms of host defense and protective immunity. Since cell migration is a process executed by all nucleated cells, we believe that our studies will have significant impact in understanding other processes such as morphogenesis and tissue regeneration.