脂筏氧化还原信号在柚皮素抑制巨噬细胞脂质吸收中作用的研究

脂筏是细胞膜上具有独立功能的微区，可介导炎症、氧化应激以及胞内外的物质运输。质膜脂筏上的NADPH氧化酶2（Nox2）与胞内相关亚基结合、激活氧化还原信号，促进巨噬细胞对外源脂质的吸收。课题组前期发现柚皮素可降低巨噬细胞Nox2活性、抑制CD36脂筏招募和对oxLDL的摄取，提示脂筏在柚皮素调节泡沫细胞形成中可能具有重要作用。本研究中，我们将围绕脂筏，阐明柚皮素对脂筏介导的氧化还原信号、脂质摄取的调节作用。课题组首先将从体外进一步明确柚皮素是否抑制脂筏聚集、酸性鞘磷脂酶、神经酰胺和活性氧生成；分析柚皮素对CD36棕榈酰化修饰、胞内脂筏转位、脂质摄取的调控作用。接着，以高脂诱导的apoE敲除小鼠为模型，经柚皮素、上调Nox2活性等处理，体内确定脂筏及其所介导的氧化还原信号与巨噬细胞脂质蓄积之间的关系。该研究有助于我们进一步了解柚皮素在泡沫细胞形成中的作用机制。

Lipid rafts are membrane microdomains with multiple functions, which contribute inflammatory, oxidative stress response and facilitate transmembrane material transport. NADPH oxdase-2 (Nox2) in plasma membrane lipid rafts recruits other cytosolic subunits to active redox signaling and promote macrophage lipid uptake. Previously, we identified that naringenin reduced Nox2 activity, inhibited CD36 lipid raft recruitment and oxLDL uptake, which suggest the lipid rafts play an important role in naringenin-regulated foam cell formation. In this study, we will focus on lipid rafts and determine the effects of naringenin on lipid raft redox signaling and lipid uptake. First, we will examine whether naringenin inhibit lipid rafts cluster, acid sphingomyelinase activity, ceramide content and reactive oxygen species (ROS) generation; we will analyze the regulation of naringenin on CD36 palmitoylation, translocation to lipid rafts and cellular lipid uptake in macrophages. Second, apoE knockout mice (apoE-/-) will be used as animal model. After treatment with naringenin and/or increasing Nox2 activity, we determine the relationship among oxidative stress, CD36 lipid raft recruitment and lipid cellular accumulation in vivo. The studies will further our understanding of the underlying mechanism of naringenin on foam cell formation.