Defective isoforms of ApoE induce atherogenesis via unfolded protein responses

描述(申请人提供)：本项目研究载脂蛋白E受体2(ApoER2)和极低密度脂蛋白受体(VLDLR)的抗动脉粥样硬化作用，使用部分Reelin多肽(R5-6C)作为激活这些受体的工具。这些研究扩展了我们对动脉粥样硬化发病机制和治疗策略的研究。我们最近报道，ApoER2和VLDLR在小鼠巨噬细胞中被其天然配体apoE和reelin激活，导致失活-1(Dab1)激活，上调ATP结合盒转运体A1(ABCA1)的表达，加速胆固醇外流，减少细胞内胆固醇积累。然而，其他一些研究VLDLR和ApoER2在动脉粥样硬化发病机制中的作用的研究人员指出，这些受体的激活能够诱导促动脉粥样硬化或抗动脉粥样硬化的作用，这可能取决于涉及的特定配体和信号通路。具体地说，抗动脉粥样硬化的配体，如reelin、apoE和激活的蛋白C(APC)，激活依赖于Dab1的信号通路，并抑制可能导致炎症和泡沫细胞形成的细胞事件。在……里面 相反，促动脉粥样硬化的配体，如脂蛋白、中性粒细胞多肽和凝血因子XI，可能通过激活p38介导的途径，增加细胞内胆固醇的积累并诱导细胞黏附。本项目旨在确定VLDLR/ApoER2在体外和体内的抗动脉粥样硬化作用，使用部分卷轴蛋白多肽(R5-6C)作为激动剂。我们选择reelin是因为它只与VLDLR和ApoER2结合。相反，apoE和APC能够与其他受体以及VLDLR和ApoER2相互作用。我们的中心假设是，R5-6C激活VLDLR/ApoER2-Dab1通路将上调抗动脉粥样硬化分子，下调促动脉粥样硬化分子，从而抑制动脉粥样硬化的发展。SA1将研究R5-6C基因转移对小鼠动脉粥样硬化的影响。虽然主要的焦点是动脉粥样硬化病变，但我们也将研究R5-6C基因转移对动脉粥样硬化区促动脉粥样硬化蛋白和抗动脉粥样硬化蛋白表达的影响以及对血脂/血糖水平的影响。SA2将提出一个工作假设，即R5-6C通过激活ApoER2/VLDLR-Dab1通路来抑制oxLP诱导的单核细胞(MNC)与内皮细胞(ECs)的黏附。重点介绍VLDLR/ApoER2-Dab1通路在R5-6C诱导的单核细胞与内皮细胞黏附改变中的作用以及内皮细胞抗黏附和促黏附分子的表达。SA3将检验一个工作假说，即R5-6C通过激活ApoER2/VLDLR-Dab1途径抑制泡沫细胞的形成。本实验旨在探讨R5-6C是否阻断巨噬细胞与脂蛋白的结合和摄取，以及VLDLR/ApoER2-Dab1通路的激活是否是R5-6C调节胆固醇代谢相关基因表达和抑制泡沫细胞形成的机制。如果成功，这个项目将提供一个 设计VLDLR/ApoER2激动剂的科学基础，如reelin模拟物，用于治疗动脉粥样硬化。

DESCRIPTION (provided by applicant): This project investigates the anti-atherogenic role of apolipoprotein E receptor 2 (apoER2) and very low- density lipoprotein receptor (VLDLR), using a partial reelin peptide (R5-6C) as a tool to activate these receptors. These studies extend our research on the pathogenesis of, and therapeutic strategies for atherosclerosis. We recently reported that activation of apoER2 and VLDLR by their natural ligands apoE and reelin in murine macrophages results in activation of disabled-1 (Dab1), upregulation of ATP-binding cassette transporter A1 (ABCA1) expression, accelerated cholesterol efflux and reduced cellular cholesterol accumulation. However a number of other investigators studying the impact of VLDLR and apoER2 on the pathogenesis of atherosclerosis noted that activation of these receptors is able to induce either pro- or anti- atherogenic effects, possibly dependent on the particular ligands and signaling pathways involved. Specifically, anti-atherogenic ligands, such as reelin, apoE and activated protein C (APC), activate a Dab1-dependent signaling pathway and inhibit cellular events that potentially contribute to inflammation and foam cell formation. In contrast pro-atherogenic ligands such as lipoproteins, neutrophil peptides and coagulation factor XI, elevate intracellular cholesterol accumulation and induce cell adhesion, possibly by activation of a p38-mediated pathway. This project is designed to define the anti-atherogenic role of VLDLR/apoER2 in vitro and in vivo, using a partial reelin peptide (R5-6C) as an agonist. We chose reelin because it exclusively binds VLDLR and apoER2. In contrast, apoE and APC are able to interact with other receptors as well as VLDLR and apoER2. Our central hypothesis is that activation of the VLDLR/apoER2-Dab1 pathway by R5-6C will upregulate anti- atherogenic molecules, down-regulate pro-atherogenic molecules, and therefore inhibit atherosclerosis development. SA1 will study the effect of R5-6C gene transfer on atherosclerosis in mouse models. Though the primary focus is atherosclerotic lesions, we will also study the effect of R5-6C gene transfer on the expression of pro- and anti-atherogenic proteins in the atherosclerotic area as well as on the level of plasma lipids/glucose. SA2 will tes a working hypothesis that R5-6C inhibits oxLP-induced adhesion of monocytes (MNCs) to endothelial cells (ECs) by activation of the apoER2/VLDLR-Dab1 pathway. An emphasis will be placed on the contribution of VLDLR/apoER2-Dab1 pathway to R5-6C-induced changes in adhesion of MNCs to ECs and the expression of endothelial anti- and pro-adhesion molecules. SA3 will test a working hypothesis that R5-6C inhibits foam cell formation by activation of the apoER2/VLDLR-Dab1 pathway. Experiments are designed to explore whether R5-6C blocks macrophage binding and uptake of lipoproteins, and whether activation of the VLDLR/apoER2- Dab1 pathway is a mechanism by which R5-6C regulates the expression of genes related to cholesterol metabolism and inhibits foam cell formation. If successful, this project will provide a scientific basis for designing VLDLR/apoER2 agonists, such as reelin mimetics, to treat atherosclerosis.