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

描述（由申请人提供）：三叶因子家族2 （TFF2）是在胃粘膜颈细胞（和淋巴细胞）中表达的三叶因子家族的独特成员。TFF2在胃瘤前病变中与p53突变同时上调，p53功能的丧失与幽门螺杆菌感染的免疫反应减弱有关。我们实验室最近的研究表明，TFF2-/-小鼠表现出高度炎症表型，这与TFF2作为抗炎肽的假设作用一致。长期感染猫链球菌后，TFF2-/-小鼠表现出ifn - γ水平升高和粘膜CD4+ T细胞增加。我们实验室的研究表明，TFF2的转录是由转录因子p53和KLF4通过AP-1位点调控的。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Ca++信号，但在SDF-1存在时，TFF2部分抑制SDF-1依赖性信号和趋化性。我们的总体假设是上皮源性TFF2受p53调控，抑制sdf -1依赖性淋巴细胞趋化和存活，从而减少炎症。我们提出研究TFF2的功能及其调控的具体目的如下：(1)。探讨p53和KLF4在TFF2基因表达调控中的作用。我们将在胃癌细胞系中探讨p53在抑制TFF2基因表达中的作用，以及KLF4在通过AP-1位点激活TFF2基因表达中的作用，并明确共激活因子和共抑制因子的作用。（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、下游信号通路和受体脱敏的差异。(3)。显示TFF2-CXCR4相互作用在T细胞功能调节中的重要性。我们将在体外和体内模型系统中测试TFF2调节T细胞迁移和存活的能力。(4)阐明TFF2在胃上皮与造血室中的重要性。骨髓嵌合、RAG2-/-重构模型以及TFF2-/-和p53突变小鼠之间的杂交将被用来验证TFF2抑制胃炎症的观点。总之，这些研究将确定TFF2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，慢性炎症通常会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 (TFF2)，这是一种三环（三叶草叶）形状的肽，在慢性炎症的胃中上调，并确定了其主要受体，即CXCR4。这种受体被一种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TFF2通过调节T细胞对SDF-1的反应而起作用。TFF2受到肿瘤抑制基因p53的抑制，我们也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.