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

描述（由申请方提供）：三叶因子家族2（TFF 2）是在胃粘液颈细胞（和淋巴细胞）中表达的三叶因子家族的独特成员。TFF 2在胃肿瘤前病变中上调，与p53突变一致，p53功能的丧失与对螺杆菌感染的免疫应答的减弱有关。我们实验室最近的工作表明，TFF 2-/-小鼠表现出高度炎症表型，这与TFF 2作为抗炎肽的假定作用一致。针对H.猫感染后，TFF 2-/-小鼠表现出IFN-γ水平增加和粘膜CD 4 + T细胞增加。本实验室的工作表明，TFF 2的转录受转录因子p53和KLF 4通过AP-1位点的调控。此外，我们还意外地观察到TFF 2是CXCR 4受体的天然配体，是G蛋白偶联受体和SDF-1的主要受体。TFF 2是CXCR 4的部分激动剂，能够激活Ca++信号传导，但在SDF-1存在下，TFF 2部分抑制SDF-1依赖性信号传导和趋化性。我们的总体假设是上皮来源的TFF 2受p53调节，抑制SDF-1依赖性淋巴细胞的趋化性和存活，从而减少炎症。本研究拟从以下几个方面对TFF 2的功能和调控进行研究：（1）.研究p53和KLF 4在TFF 2基因表达调控中的作用。通过AP-1位点，p53在抑制TFF 2基因表达中的作用和KLF 4在激活TFF 2基因表达中的作用将在胃癌细胞系中进行探索，并确定共激活因子和共抑制因子的作用。（二）、确认TFF 2是部分激动剂，并确定TFF 2如何通过CXCR 4调节SDF-1信号传导。我们将研究竞争，Galphai的作用，下游信号通路，以及受体脱敏的差异。（三）、显示TFF 2-CXCR 4相互作用在调节T细胞功能中的重要性。我们将使用体外和体内模型系统测试TFF 2调节T细胞迁移和存活的能力。(4)阐明TFF 2在胃上皮与造血区室中的重要性。将采用骨髓嵌合体、RAG 2-/-重建模型以及TFF 2-/-和p53突变小鼠之间的杂交来测试TFF 2抑制胃炎症的概念。总的来说，这些研究将确定TFF 2在胃免疫调节中的作用。公共卫生相关性：炎症反应在抵御感染性病原体方面起着重要作用，但随着时间的推移可能导致器官衰竭或恶性肿瘤。因此，慢性炎症通常导致许多修复机制的上调，以及有助于抑制或抑制炎症反应的肽的表达。我们研究了三叶因子家族2（TFF 2），一种在慢性炎症胃中上调的三环（三叶草叶）形肽，并鉴定了其主要受体，称为CXCR 4。该受体被调节淋巴细胞功能的趋化因子（称为SDF-1）激活，因此我们假设TFF 2通过调节T细胞对SDF-1的反应发挥作用。TFF 2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.