Mechanisms of Adenosine Protection

描述（由申请人提供）：炎症伴随着组织代谢的实质性变化。炎症的主要代谢特征之一是缺氧，它最近被认为对炎症性疾病的预后有显著影响。在疾病早期，这种“炎症性缺氧”在很大程度上是由需要氧气的炎症细胞类型，特别是中性粒细胞的募集引起的。近年来，我们专注于确定炎症性缺氧的靶点和分子途径。这些研究的结果已经定义了一系列新的信号机制，其中缺氧（体外和体内）驱动细胞外核苷酸的代谢，产生大量的细胞外腺苷。该途径的核心是确定缺氧诱导因子（HIF）作为Ado代谢所需酶（特别是CD73）的重要调节剂，从而确定HIF调节的Ado生成是一种内源性抗炎途径。正在进行的研究表明，Ado通过Cullins（一个对泛素连接酶的募集至关重要的蛋白家族）的活性去醛化来调节HIF。基于这些初步研究，我们假设炎症反应早期产生的Ado作为一种前馈抗炎机制，通过直接作用于粘膜HIF稳定。为了验证这一假设，有三个特定的目标：在特定目标1中，我们将定义中性粒细胞和上皮细胞对炎症部位Ado生成的贡献。Specific Aim 2将扩展初步数据以阐明ado介导的Cullin-2去类黄酮化机制。特异性目的3将探讨Ado在hif介导的保护中的作用。本提案的总体目标是识别炎症性缺氧期间粘膜内HIF和Ado的新代谢信号。

DESCRIPTION (provided by applicant): Inflammation is accompanied by a substantial shift in tissue metabolism. One of the major metabolic signatures of inflammation is hypoxia, which is recently appreciated to significantly influence inflammatory disease outcome. Early in the disease process, such "inflammatory hypoxia" results, in large extent, from the recruitment of oxygen demanding inflammatory cell types, particularly neutrophils. In recent years, we have focused on defining targets and molecular pathways set into motion by inflammatory hypoxia. Results from these studies have defined a series of novel signaling mechanisms in which hypoxia (both in vitro and in vivo) drives the metabolism of extracellular nucleotides toward the generation of large amounts of extracellular adenosine. Central to this pathway was the identification of hypoxia-inducible factor (HIF) as an important regulator of the enzymes necessary for Ado metabolism (esp. CD73), thus identifying HIF-regulated Ado production as an endogenous anti-inflammatory pathway. Ongoing studies have revealed that Ado regulates HIF through the active deneddylation of Cullins, a family of proteins critical for the recruitment of ubiquitin ligases. Based on these preliminary studies, we hypothesize that Ado generated early in the inflammatory response functions as a feed-forward anti- inflammatory mechanism through direct actions on mucosal HIF stabilization. Three specific aims are directed at testing this hypothesis: In Specific Aim 1, we will define the contribution of neutrophils and epithelia to Ado generation at sites of inflammation. Specific Aim 2 will extend preliminary data to elucidate mechanisms of Ado-mediated Cullin-2 de-neddylation. Specific Aim 3 will Probe the role of Ado to HIF-mediated protection. The overall aim of this proposal is to identify novel metabolic signaling by HIF and Ado within the mucosa during inflammatory hypoxia. PUBLIC HEALTH RELEVANCE: This proposal aims at understanding the role of metabolism in mucosal inflammation such as that observed in inflammatory bowel disease (IBD). Results from the studies proposed here will go far to resolve a number of unanswered questions in the field of inflammation, including: What cell types contribute most significantly to the metabolic changes associated with inflammation? Are these metabolic changes protective or detrimental to the tissue? Can these metabolic changes be targeted for therapeutic benefit? Answers to these questions through experiments proposed here will provide an important foundation for which to integrate novel therapeutic approaches for mucosal inflammation.