Role of beta 2 integrins in macrophage fusion

β2整合素在巨噬细胞融合中的作用

• 批准号: 9127306
• 负责人: Tatiana P Ugarova
• 金额: $ 38.63万
• 依托单位: ARIZONA STATE UNIVERSITY-TEMPE CAMPUS
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-07-01 至 2019-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9127306
• 关键词: Accounting; Actins; Adhesives; Apolipoprotein E; Arterial Fatty Streak; Atherosclerosis; Binding; Biochemical; Biology; Blood Vessels; Bone Marrow Transplantation; CD18 Antigens; CD47 gene; Cardiovascular Diseases; Cardiovascular Pathology; Cathepsins; Cell Surface Receptors; Cells; Cellular biology; Cholates; Chronic; Complex; Crossbreeding; Data; Disease; Disease Progression; Electron Microscopy; Environment; Enzymes; Event; Exhibits; Family; Fibrinogen; Filopodia; Fingers; Fluorescent Antibody Technique; Funding; Giant Cells; Goals; Granuloma; Health; Hereditary Disease; High Fat Diet; Host Defense; ITGAM gene; ITGB2 gene; Immunofluorescence Microscopy; Immunoglobulins; Impairment; Inflammation; Inflammatory; Inflammatory Response; Integrins; Intercellular adhesion molecule 1; Knowledge; Lead; Leukocytes; Ligand Binding; Ligands; Macrophage-1 Antigen; Mass Spectrum Analysis; Mediating; Membrane; Molecular; Mus; PTPNS1 gene; Pathogenesis; Pathology; Peptide Hydrolases; Peptide Library; Play; Process; Property; Proteins; RNA Interference; Reaction; Recombinants; Research; Resolution; Role; Serum; Specificity; Structure; Surface; Techniques; Testing; Therapeutic; Up-Regulation; adhesion receptor; base; behavioral study; combinatorial; in vivo Model; insight; knock-down; macrophage; member; mutant; neutrophil; novel therapeutic intervention; protein protein interaction; receptor; response; therapeutic target

 DESCRIPTION (provided by applicant): Leukocyte integrin αMβ2 (Mac-1) plays a pivotal role in normal protective inflammatory response and pathological inflammation. It is also a potential therapeutic target in many diseases in which inflammation plays an essential role, including cardiovascular diseases. The diverse functions and activities ascribed to Mac-1 arise from its ability to bind a multitude of ligands. We have recently discovered a new function of Mac-1. In particular, we found that Mac-1 is involved in macrophage fusion, a salient feature of chronic inflammation in many diseases, including atherosclerosis and other vascular pathologies. Macrophage fusion requires a specific proinflammatory environment and leads to the formation of multinucleated giant cells (MGCs). Although MGCs have been first discovered in the middle of the 19th century in tuberculoid granuloma and since then were found in numerous inflammatory diseases, the molecular mechanisms of fusion bringing two membranes together remain unknown. In our preliminary studies we found that ICAM-1, a counter-receptor of Mac-1, also promotes macrophage fusion. However, deficiency of ICAM-1 resulted only in a partial decrease of fusion which could not be accounted for the strong impairment of fusion observed in Mac-1- deficient macrophages. These results suggested than other Mac-1 ligands are involved in fusion. We have found that MFR (macrophage fusion receptor/SIRPα), a receptor upregulated on the surface of fusing macrophage, interacts with Mac-1. Like ICAM-1, MFR is a member of the immunoglobulin superfamily of transmembrane receptors and one of the molecules implicated in macrophage fusion. Based on this discovery and some preliminary data, we hypothesize that Mac-1 is required for macrophage fusion during which it interacts with MFR. Specific Aim 1 is to test this hypothesis. Recombinant techniques, studies of protein-protein interactions, RNA interference, bone marrow transplantations, and combinatorial peptide libraries will be used to elucidate how Mac-1 binds MFR and clarify the role of this interaction in fusion. Specific Aim 2 will test the hypothesis that filopodia and microspikes are fusion intermediates in macrophage fusion and that Mac-1 is required for the formation of these structures. The hypothesis is based on our discovery of these hitherto unknown structures during macrophage fusion. Ultrastructural studies using high-resolution electron microscopy, confocal immunofluorescence microscopy, and TIRF will be used to characterize these fusion intermediates. Specific Aim 3 is to test the hypothesis that MGCs, which secrete potent elastolytic enzymes, contribute to the progression of atherosclerosis. The formation of MGCs in atherosclerotic plaques and the role of Mac-1 will be examined in ApoE-/- and LDLR-/- mice and the mice crossbred with Mac-1. Overall, these studies will lead to an increased understanding of the molecular mechanisms of macrophage fusion, identify previously unconsidered structures involved in the fusion of two membranes, give new insights into the biology of Mac-1, and potentially reveal unsuspected therapeutic targets.

 描述（由申请方提供）：白细胞整合素αMβ2（Mac-1）在正常保护性炎症反应和病理性炎症中起关键作用。它也是许多疾病的潜在治疗靶点，其中炎症起着重要作用，包括心血管疾病。Mac-1的多种功能和活性源于其结合多种配体的能力。我们最近发现了Mac-1的一个新功能。特别是，我们发现Mac-1参与巨噬细胞融合，这是许多疾病慢性炎症的显著特征，包括动脉粥样硬化和其他血管病变。巨噬细胞融合需要特定的促炎环境，并导致多核巨细胞（MGCs）的形成。尽管MGCs在19世纪中期首次在结核样肉芽肿中被发现，并且此后在许多炎性疾病中被发现，但将两种膜融合在一起的分子机制仍然未知。在我们的初步研究中，我们发现ICAM-1，Mac-1的反受体，也促进巨噬细胞融合。然而，ICAM-1的缺乏导致融合的部分减少，这不能解释Mac-1缺陷型巨噬细胞中观察到的融合的强烈损害。这些结果表明，比其他Mac-1配体参与融合。我们发现融合巨噬细胞表面上调的受体MFR（macrophage fusion receptor/SIRPα）与Mac-1相互作用。与ICAM-1一样，MFR是跨膜受体免疫球蛋白超家族的成员，也是巨噬细胞融合中涉及的分子之一。基于这一发现和一些初步数据，我们假设Mac-1是巨噬细胞融合所必需的，在此期间，它与MFR相互作用。具体目标1是检验这一假设。重组技术，蛋白质-蛋白质相互作用的研究，RNA干扰，骨髓移植和组合肽库将用于阐明Mac-1如何结合MFR，并阐明这种相互作用在 核聚变具体目标2将测试的假设，即丝状伪足和微刺是融合的中间体在巨噬细胞融合和Mac-1是需要这些结构的形成。这一假说是基于我们在巨噬细胞融合过程中发现了这些迄今为止未知的结构。使用高分辨率电子显微镜，共聚焦免疫荧光显微镜和TIRF的超微结构研究将被用来表征这些融合中间体。具体目标3是测试的假设，MGCs，分泌有效的弹性蛋白酶，有助于动脉粥样硬化的进展。将在ApoE-/-和LDLR-/-小鼠以及与Mac-1杂交的小鼠中检查动脉粥样硬化斑块中MGCs的形成和Mac-1的作用。总的来说，这些研究将增加对巨噬细胞融合的分子机制的理解，确定以前未考虑的参与两种膜融合的结构，对Mac-1的生物学提供新的见解，并可能揭示未知的治疗靶点。