Leukotrienes and Lung Inflammation

描述（由申请人提供）：肥大细胞、巨噬细胞和多形核白细胞（PMN），通过合成和释放生物活性脂质白三烯（LT）B4和LTC4来启动和放大肺部炎症。从细胞中释放出来后，LTC4转化为LTD4。这些类二十烷酸通过调节白细胞募集、内皮细胞渗透性、成纤维细胞增殖和平滑肌收缩来帮助“塑造”肺部炎症反应。LTC4、LTD4和LTB4是哮喘和特发性肺纤维化（IFF）发病机制的核心。它们对宿主防御感染也至关重要。因此，细胞如何调节这些类二十烷醇的合成是这些疾病发病机制的核心。LTC4的形成需要核膜上至少四种蛋白的功能性相互作用。它们是胞质磷脂酶A2 （cPLA2）、5-脂氧合酶（5-LO）、5-脂氧合酶激活蛋白（FLAP）和LTC4合成酶；LTA4水解酶代谢LTA生成LTB4。我们使用生物化学和分子成像相结合的方法来证明5-LO、FLAP和LTC4合成酶在核膜上包含额外蛋白质的新型、依赖激活的大分子复合物中的相互作用。我们还发现了一个10 kDa的蛋白（Associated protein 10 kDa, AP-10），在细胞激活和复合物形成后从FLAP中分离。该建议的假设是这些复合物是细胞活化和LT合成之间的联系。本研究的长期目标是了解这些复合物的组装、降解和区区化如何在分子、细胞生物学和体内水平上调节LTs的形成。提出了三个具体目标。在Specific Aim 1中，我们将确定5-LO膜复合物是如何组装和组织的。在特异性目标2中，我们将鉴定AP-10蛋白。在Specific Aim 3中，我们将验证LTC4和LTB4的合成在细胞质和细胞核之间划分的假设，以及新发现的内膜5-LO复合物调节LTB4的合成。这些目标的完成将有助于确定炎症性肺病的新机制和潜在的治疗方法。

DESCRIPTION (provided by applicant): Mast cells, macrophages, and polymorphonuclear leukocytes (PMN), initiate and amplify inflammation in the lung by synthesizing and releasing the bioactive lipids leukotriene (LT)B4, and LTC4. After its release from cells, LTC4 is converted to LTD4. These eicosanoids help "shape" the pulmonary inflammatory response by regulating leukocyte recruitment, endothelial permeability, fibroblast proliferation, and smooth muscle contraction. LTC4, LTD4 and LTB4 are central to the pathogenesis of asthma and idiopathic pulmonary fibrosis (IFF). They are also critical for host defense to infection. How cells modulate the synthesis of these eicosanoids is therefore central to the pathogenesis of these diseases. The formation of LTC4 requires the functional interaction of at least four proteins on the nuclear envelope. These are cytosolic phospholipase A2 (cPLA2), 5-lipoxygenase (5-LO), the 5-lipoxygenase-activating protein (FLAP), and LTC4 synthase; the metabolism of LTA by LTA4 hydrolase yields LTB4. We have used a combination of biochemistry and molecular imaging to demonstrate the interaction of 5-LO, FLAP, and LTC4 synthase in novel, activation- dependent, macromolecular complexes on the nuclear envelope that include additional proteins. We have also identified a 10 kDa protein (Associated Protein 10 kDa, AP-10) that dissociates from FLAP after cell activation concurrent with complex formation. The hypothesis of this proposal is that these complexes are the link between cell activation and LT synthesis. The broad long-term objective of this proposal is to understand how the assembly, degradation, and compartmentalization of these complexes regulate the formation of LTs on molecular, cell biological, and in vivo levels. Three Specific Aims are proposed. In Specific Aim 1 we will determine how 5-LO membrane complexes are assembled and organized. In Specific Aim 2 we will identify the AP-10 protein. In Specific Aim 3 we will test the hypothesis that the synthesis of LTC4 and LTB4 is compartmentalized between the cytosol and nucleus and that newly identified inner membrane 5-LO complexes regulate the synthesis of LTB4. The completion of these aims will allow the identification of novel mechanisms and, potentially, therapeutic approaches, to inflammatory pulmonary diseases.