The Function and Regulation of Trefoil Factor Family 2 (TFF2)

描述(申请人提供)：三叶因子家族2(TFF2)是三叶因子家族中唯一的成员，表达于胃粘膜颈部细胞(和淋巴细胞)。TFF2在伴有P53突变的胃癌中表达上调，P53功能的丧失与对幽门螺杆菌感染的免疫反应抑制有关。我们实验室最近的工作表明，TFF2-/-小鼠表现出高炎症表型，这与TFF2作为抗炎肽的假定作用一致。作为对长期感染H.Felis的反应，TFF2-/-小鼠表现出干扰素-γ水平增加和粘膜CD4T细胞增加。我们实验室的工作表明，TFF2的转录是通过AP-1位点受转录因子P53和KLF4调控的。此外，我们还意外地观察到，TFF2是CXCR4受体的天然配体，CXCR4受体是G蛋白偶联受体，也是SDF-1的主要受体。TFF2是CXCR4的部分激动剂，能够激活钙信号，但在SDF-1存在的情况下，TFF2部分抑制SDF-1依赖的信号和趋化作用。我们的总体假设是，上皮源性TFF2受P53调节，抑制SDF-1依赖的淋巴细胞趋化和存活，从而减少炎症。我们建议通过以下具体目标来研究TFF2的功能和调控：(1)。探讨P53和KLF4在TFF2基因表达调控中的作用。P53在抑制TFF2基因表达中的作用和KLF4通过AP-1位点激活TFF2基因表达的作用将在胃癌细胞系中进行探索，并确定共激活因子和辅助抑制因子的作用。(2)。确认TFF2是部分激动剂，并确定TFF2如何通过CXCR4调节SDF-1信号。我们将研究竞争，Galphai的作用，下游信号通路，以及受体脱敏方面的差异。(3)。显示TFF2-CXCR4相互作用在T细胞功能调节中的重要性。我们将使用体外和体内模型系统来测试TFF2调节T细胞迁移和存活的能力。(4)阐明TFF2在胃上皮与造血室的重要性。骨髓嵌合体、RAG2-/-重建模型以及TFF2-/-和P53突变小鼠之间的杂交将被用来测试TFF2抑制胃炎症的概念。总体而言，这些研究将确定TFF2在胃部免疫调节中的作用。与公共卫生相关：炎症反应在抵御感染病原体方面发挥着重要作用，但随着时间的推移，可能会导致器官衰竭或恶性肿瘤。因此，慢性炎症通常会导致一些修复机制的上调，以及有助于抑制或抑制炎症反应的多肽的表达。我们研究了三叶因子家族2(TFF2)，一种在慢性炎症胃中上调的三环(三叶草)形状的肽，并确定了它的主要受体，即CXCR4。这种受体是由一种调节淋巴细胞功能的趋化因子(SDF-1)激活的，因此我们假设TFF2通过调节T细胞对SDF-1的反应来发挥作用。TFF2被肿瘤抑制基因P53抑制，我们还将试图通过其调节免疫系统的活性来证明它是该肿瘤抑制基因的重要下游靶点。

DESCRIPTION (provided by applicant): Trefoil factor family 2 (TFF2) is a unique member of the trefoil family expressed in gastric mucous neck cells (and lymphocytes). TFF2 is upregulated in gastric preneoplasia coincident with p53 mutations, and loss of p53 function is associated with dampening of immune responses to Helicobacter infection. Recent work from our laboratory has shown that TFF2-/- mice show a hyper-inflammatory phenotype, consistent with a putative role for TFF2 as an anti-inflammatory peptide. In response to long-term H. felis infection, TFF2-/- mice exhibit increased IFN-gamma levels and increased mucosal CD4+ T cells. Work from our laboratory has demonstrated that TFF2 transcription is regulated by the transcription factors p53 and KLF4 though an AP-1 site. In addition, we have made the unexpected observation that TFF2 is a natural ligand for the CXCR4 receptor, a G-protein coupled receptor and the primary receptor for SDF-1. TFF2 is a partial agonist for CXCR4, able to activate Ca++ signaling but in the presence of SDF-1, TFF2 partial inhibits SDF-1-dependent signaling and chemotaxis. Our overall hypothesis is that epithelial-derived TFF2 is regulated by p53 and inhibits SDF-1-dependent lymphocyte chemotaxis and survival, thus reducing inflammation. We propose to study the function and regulation of TFF2 through the following specific aims: (1). Investigate the role for p53 and KLF4 in the regulation of TFF2 gene expression. The role of p53 in repressing, and KLF4 in activating, TFF2 gene expression through an AP-1 site will be explored in gastric cancer cell lines and the roles of co-activators and co-repressors defined. (2). Confirm that TFF2 is a partial agonist and determine how TFF2 modulates SDF-1 signaling through CXCR4. We will investigate competition, the role of Galphai, downstream signaling pathways, and differences in receptor desensitization. (3). Show the importance of the TFF2-CXCR4 interaction in the modulation of T cell function. We will test the ability of TFF2 to regulate T cell migration and survival using both in vitro and in vivo model systems. (4) Clarify the importance of TFF2 in the gastric epithelium versus the hematopoietic compartment. Bone marrow chimerics, RAG2-/- reconstitution models, and crosses between TFF2-/- and p53 mutant mice will be employed to test the notion that TFF2 dampens gastric inflammation. Overall, these studies will define the role of TFF2 in immune modulation of the stomach. PUBLIC HEALTH RELEVANCE: The inflammatory response plays an important role in fending off infectious pathogens but over time can lead to organ failure or malignancy. Thus, chronic inflammation leads typically to the upregulation of a number of repair mechanisms, as well as the expression of peptides that can help to dampen or suppress the inflammatory response. We have studied trefoil factor family 2 (TFF2), a three-looped (clover leaf) shaped peptide that is upregulated in the chronically inflamed stomach, and have identified its primary receptor, which is known as CXCR4. This receptor is activated by a chemokine (known as SDF-1) that regulates lymphocyte function and thus we postulate that TFF2 functions by modulating responses by T cells to SDF-1. TFF2 is suppressed by the tumor suppressor gene p53, and we will also attempt to show that it is an important downstream target of this tumor suppressor through its activity in regulating the immune system.