Role of Transglutaminase 2 in Celiac Sprue

摘要 乳糜泻(CED)是一种由面筋引起的小肠炎性疾病，对于这种疾病没有非饮食 治疗已被批准用于临床。在这个正在进行的合作项目中，我们研究了致病作用 转谷氨酰胺酶2(TG2)，CED的有效药物靶点，通过工具和 化学生物学和粘膜免疫学的概念。在过去的赠款周期中，我们发现了 一种新的抗原性谷蛋白多肽被有效地护送到抗原内吞体内的途径 通过形成包含TG2、2-巨球蛋白(2M)和低密度的复合体来呈现细胞 脂蛋白受体相关蛋白1(LRP1)。在下一个周期中，我们将描述TG2的这种机制- 通过以下特定目的依赖炎症T细胞的激活： 目的1：LRP1介导的面筋抗原分子间相互作用的结构-功能分析 演示文稿：我们将从生化角度描述TG2和TG2之间的代表性中间体是如何形成的 一种面筋多肽被2M识别。我们的目标是确定促进2M-TG2的分子特征 识别和多肽在这种三组分相互作用中的作用。另外，我们还将研究如何 得到的多肽-Tg2-LRP12M复合体可被受体识别和内吞。 目的2：明确LRP1信号通路在CED发病机制中的作用： 虽然LRP1介导的面筋抗原内吞作用已经在培养细胞中进行了研究，但我们还不知道 脱酰胺和摄取面筋蛋白多肽并将其呈递给CED特异性的小肠细胞的鉴定 T细胞。使用通过LRP1介导的内吞作用的荧光肽和多肽模拟物，我们将 确定在选定的小鼠品系中表现出这种特性的肠道细胞。反过来，我们将利用鼠标 通过这笔赠款的支持建立了模型，以研究Tg2-2M-LRP1途径在 丧失对饮食面筋的口服耐受性，以及面筋引起的绒毛萎缩。 我们提出的研究不仅提供了从根本上开创我们的 对CED发病机制的了解，但由此产生的工具和方法可以被用来研究 Tg2-2M-LRP1胞内途径与其他病理生理情况的相关性。

SUMMARY Celiac disease (CeD) is a gluten-induced inflammatory disorder of the small intestine for which no non-dietary therapy has been approved for clinical use. In this ongoing collaborative project, we study the pathogenic role of transglutaminase 2 (TG2), a validated drug target for CeD, through a synergistic combination of tools and concepts from chemical biology and mucosal immunology. During the past grant cycle, we have uncovered a novel pathway by which antigenic gluten peptides are potently escorted into the endosomes of antigen presenting cells through the formation of complexes involving TG2, 2-macroglobulin (2M), and low density lipoprotein receptor-related protein 1 (LRP1). In the next cycle, we will characterize this mechanism for TG2- dependent inflammatory T cell activation through the following Specific Aims: Aim 1: Structure-function analysis of molecular interactions involved in LRP1-mediated gluten antigen presentation: We will biochemically characterize how a representative intermediate formed between TG2 and a gluten peptide is recognized by 2M. Our goal is to define the molecular features facilitating 2M-TG2 recognition and the role of the peptide in this three-component interaction. Separately, we will also study how the resulting peptide-TG2-2M complex is recognized and endocytosed by the LRP1 receptor. Aim 2: Defining the pathogenic role of the LRP1 pathway for gluten peptide uptake in CeD pathogenesis: While LRP1-mediated gluten antigen endocytosis has been studied in cultured cells, we do not know the identities of small intestinal cells that deamidate and take up gluten peptides and present them to CeD-specific T cells. Using fluorogenic peptides and peptidomimetics that undergo LRP1-mediated endocytosis, we will identify intestinal cells that exhibit this property in selected strains of mice. In turn, we will leverage mouse models developed through the support of this grant to examine the role of the TG2-2M-LRP1 pathway in the loss of oral tolerance to dietary gluten as well as the onset of gluten-induced villous atrophy. Not only does our proposed research offer the promise of breaking fundamentally new ground in our understanding of CeD pathogenesis, but the resulting tools and methods could be leveraged to investigate the relevance of the TG2-2M-LRP1 endocytic pathway in other patho-physiological situations.