FAK regulation of cholesterol influx and efflux in foam cells

FAK对泡沫细胞中胆固醇流入和流出的调节

• 批准号: 10729865
• 负责人: Steve Lim
• 金额: $ 36.48万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10729865
• 关键词: FAK; regulation; cholesterol; influx; efflux

Project Summary Atherosclerosis arises as a result of excess accumulation of cholesterol within vascular cells, with macrophages comprising a majority of these lipid-laden foam cells within atherosclerotic lesions. Lipid-lowering therapies, such as statins, have proven beneficial, but still only benefit a subset of patients. As such, there is currently a need to develop new treatment options that can treat a larger portion of atherosclerosis patients to reduce cardiovascular disease mortality. One potential strategy for treating atherosclerosis is to reduce foam cells by decreasing cholesterol uptake (influx) and/or to promote cholesterol release (efflux) in macrophages. However, no current therapy targets these mechanisms. Foam cells within atherosclerotic lesions are developed from too much cholesterol influx without efficient efflux. Focal adhesion kinase (FAK) is an integrin- associated tyrosine kinase which contributes to vascular cell migration, proliferation, and inflammation. We have discovered new functions for FAK in the regulation of lipid homeostasis within macrophages. Our preliminary data revealed that FAK activation following oxidized low-density lipoprotein (oxLDL) stimulation was required for foam cell formation via endocytosis of CD36. Additionally, oxLDL increased FAK interaction with CD36 and Filamin A. Importantly, pharmacological FAK inhibition blocked FAK-CD36-Filamin A interaction and subsequent foam cell formation, suggesting that the ternary complex may contribute to oxLDL uptake. More interestingly, FAK inhibition increased expression of cellular lipid sensors peroxisome proliferator activated receptor g (PPARg) and liver X receptor a (LXRa) resulting in increased transcription of the cholesterol antiporters ABCG1 and ABCA1. FAK inhibition also increased PPARg and LXRa nuclear translocation, and this was associated with decreased expression of nuclear receptor corepressor 2 (NCOR2). In a new macrophage-specific FAK kinase-dead (KD) mouse model (CSF1R-iCre) on ApoE-/- background, we observed that FAK-KD mice fed a western diet (WD) showed less foam cell formation and reduced atherosclerotic lesions. Taken together, our central hypothesis is that FAK inhibition reduces oxLDL uptake via disruption of FAK-Filamin A-CD36 complex formation while also increasing cholesterol efflux through increased PPARg and LXRa activation via NCOR2 degradation. To decipher a molecular mechanism in which a two-fold role of FAK prevents cholesterol uptake as well as enhances efflux in macrophages. Aim 1 will determine FAK and Filamin A regulation of oxLDL-CD36 uptake in macrophages. Aim 2 will investigate FAK regulation of cholesterol efflux via PPARg and LXRa activation in foam cells. Aim 3 will evaluate the effect of FAK inhibition on preventive and therapeutic models of atherosclerosis. The proposed study will shed new insights on the role of FAK in cholesterol homeostasis in macrophage foam cells and could produce a new treatment option in atherosclerosis by reducing the foam cells via reduced cholesterol influx and elevated cholesterol efflux.

项目摘要 动脉粥样硬化是由于血管细胞中胆固醇过量的过量而引起的 巨噬细胞包括动脉粥样硬化病变中大多数这些载有脂质的泡沫细胞的巨噬细胞。降脂的降低 汀类药物等疗法已被证明有益，但仍然受益于一部分患者。因此，有 目前需要开发新的治疗方案，以治疗大部分动脉粥样硬化患者 降低心血管疾病死亡率。治疗动脉粥样硬化的一种潜在策略是减少泡沫 通过减少胆固醇摄取（涌入）和/或促进巨噬细胞中胆固醇释放（外排）的细胞。 但是，目前的治疗没有针对这些机制。动脉粥样硬化病变中的泡沫细胞是 从过多的胆固醇流入而没有有效的外排。局灶性粘附激酶（FAK）是整合素 - 相关的酪氨酸激酶有助于血管细胞迁移，增殖和炎症。我们 在调节巨噬细胞中脂质稳态的调节中发现了FAK的新功能。我们的 初步数据显示，氧化的低密度脂蛋白（OXLDL）刺激后FAK激活 通过CD36的内吞作用是泡沫细胞形成所必需的。此外，OXLDL增加了FAK相互作用 使用CD36和FilaminA。 随后的泡沫细胞形成，表明三元复合物可能有助于OXLDL摄取。 更有趣的是，FAK抑制增加了细胞脂质传感器过氧化物酶体增殖物的表达 活化的受体G（PPARG）和肝X受体A（LXRA），导致增加的转录 胆固醇抗植物ABCG1和ABCA1。 FAK抑制也增加了PPARG和LXRA核 易位，这与核受体Corepressor 2（NCOR2）的表达降低有关。 在新的巨噬细胞特异性FAK激酶死德（KD）小鼠模型（CSF1R-ICRE）中 观察到喂食西方饮食（WD）的FAK-KD小鼠显示出较少的泡沫细胞形成并减少 动脉粥样硬化病变。综上所述，我们的中心假设是FAK抑制作用可通过 FAK-FILAMIN A-CD36复合物的破坏，同时增加胆固醇外排 PPARG和LXRA通过NCOR2降解激活。破译分子机制，其中有两个倍 FAK的作用可防止胆固醇吸收，并增强巨噬细胞中的外流。 AIM 1将决定FAK 和丝蛋白A OXLDL-CD36在巨噬细胞中摄取的调节。 AIM 2将调查FAK法规 胆固醇通过PPARG和LXRA激活在泡沫细胞中。 AIM 3将评估FAK抑制作用 关于动脉粥样硬化的预防和治疗模型。拟议的研究将使有关该角色的新见解 巨噬细胞泡沫细胞中胆固醇稳态中FAK的FAK，可以在 通过减少胆固醇流入和升高的胆固醇外排来减少泡沫细胞来减少动脉粥样硬化。