Expression and function of discoidin domain receptor 1 in T cells

为了有效的免疫反应并到达靶组织，活化/效应 T 细胞必须克服血管以及基底膜和间质（主要由胶原蛋白组成）的细胞外基质 (ECM) 的屏障。使用胶原蛋白凝胶等三维 (3D) 模型表明，活化的 T 细胞利用变形虫运动在胶原蛋白中迁移，独立于强粘附力和整合素。在这方面，我们和其他人之前报道过，盘状蛋白结构域受体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，并参与激活的人类T细胞在3D胶原蛋白中的迁移。我们最近证明，绝大多数人类 Th17 细胞表达 DDR1，但不表达 DDR2，并且沉默 DDR1 或使用阻断性重组受体 (DDR1:Fc) 可显着减少其在 3D 胶原蛋白中的迁移。 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 DDR1 对于体内 Th17 细胞的募集很重要（小鼠气袋模型）。血管周围组织中效应 T 细胞迁移的机制仍知之甚少。因此，根据我们的研究，我们提出 DDR1 可能是 T 细胞迁移和免疫反应发展的主要受体。 ***目标 I：DDR1 在 T 细胞亚群中的表达和功能：为了进一步探讨 DDR1 在免疫反应中的作用，我们将检查其在人类 T 细胞亚群（包括 Th1、Th2 和 Th17 以及 Tc1、Tc2 和 Tc17）中的表达和迁移功能。将表征离体和体外极化 T 细胞亚群。***目标 II：DDR1 在 T 细胞存活和信号传导中的作用：除了促进细胞运动外，DDR1 还可以有利于 3D 胶原蛋白中的 T 细胞存活。因此，我们将通过确定 DDR1 在调节 3D 胶原中 T 细胞凋亡以及调节促凋亡和抗凋亡 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含义，并且我们将定义 DDR1 相互作用蛋白。***目标 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，我们将检查 DDR1 在抗微生物免疫中的作用（肺炎链球菌小鼠模型）感染）使用DDR1 KO小鼠和裸鼠T细胞转移实验。 ***意义：这些研究将为血管周围组织中 T 细胞迁移机制以及宿主防御和保护性免疫机制带来新的见解和理解。由于细胞迁移是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.