Epigallocatechin-3-gallate remodels apolipoprotein A-I amyloid fibrils into soluble oligomers in the presence of heparin.
Epigallocatechin-3-gallate remodels apolipoprotein A-I amyloid fibrils into soluble oligomers in the presence of heparin.
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DOI：
10.1074/jbc.ra118.002038
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发表时间：
2018-08-17
期刊：
影响因子：
--
通讯作者：
Middleton DA
中科院分区：
文献类型：
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作者：
Townsend D;Hughes E;Akien G;Stewart KL;Radford SE;Rochester D;Middleton DA
WT载脂蛋白A-I （apoA-I）的淀粉样沉积是高密度脂蛋白的主要蛋白质成分，在动脉粥样硬化斑块中积聚，可能通过增加斑块负担和不稳定性而导致冠状动脉疾病。利用CD分析、固态核磁共振波谱和透射电镜，我们在这里报道了肝素和绿茶多酚(−)-表没食子儿茶素-3-没食子酸酯（EGCG）（一种已知的淀粉样蛋白形成抑制剂和调节剂）对apoa - 1原纤维的惊人协同作用。我们发现肝素，一种糖胺聚糖（GAG）多糖的代用物，在体内与淀粉样蛋白普遍共定位，可加速单体蛋白形成apoa - 1的速度，并与不溶性原纤维相关。成熟的，不溶性的apoA-I原纤维结合EGCG (KD = 30±3 μm; Bmax = 40±3 μm)，但在肝素存在或不存在的情况下，EGCG不会改变apoA-I淀粉样蛋白从单体组装的动力学。EGCG选择性地增加了在没有肝素的情况下形成的apoA-I原纤维的特定骨干和侧链位点的移动性，但原纤维在很大程度上保留了原始形态，保持不溶性。相比之下，在肝素存在下形成的原纤维通过加入等摩尔EGCG被广泛动员，原纤维被重塑成可溶的直径为20纳米的低聚物，具有主要的α-螺旋结构，对人脐动脉内皮细胞无毒。这些结果证明了EGCG对与动脉粥样硬化相关的apoA-I淀粉样蛋白具有保护作用，并表明EGCG诱导的淀粉样蛋白重塑可能在体内受到GAGs和其他淀粉样蛋白辅助因子的严格调节，这取决于EGCG的生物利用度。
Amyloid deposits of WT apolipoprotein A-I (apoA-I), the main protein component of high-density lipoprotein, accumulate in atherosclerotic plaques where they may contribute to coronary artery disease by increasing plaque burden and instability. Using CD analysis, solid-state NMR spectroscopy, and transmission EM, we report here a surprising cooperative effect of heparin and the green tea polyphenol (−)-epigallocatechin-3-gallate (EGCG), a known inhibitor and modulator of amyloid formation, on apoA-I fibrils. We found that heparin, a proxy for glycosaminoglycan (GAG) polysaccharides that co-localize ubiquitously with amyloid in vivo, accelerates the rate of apoA-I formation from monomeric protein and associates with insoluble fibrils. Mature, insoluble apoA-I fibrils bound EGCG (KD = 30 ± 3 μm; Bmax = 40 ± 3 μm), but EGCG did not alter the kinetics of apoA-I amyloid assembly from monomer in the presence or absence of heparin. EGCG selectively increased the mobility of specific backbone and side-chain sites of apoA-I fibrils formed in the absence of heparin, but the fibrils largely retained their original morphology and remained insoluble. By contrast, fibrils formed in the presence of heparin were mobilized extensively by the addition of equimolar EGCG, and the fibrils were remodeled into soluble 20-nm-diameter oligomers with a largely α-helical structure that were nontoxic to human umbilical artery endothelial cells. These results argue for a protective effect of EGCG on apoA-I amyloid associated with atherosclerosis and suggest that EGCG-induced remodeling of amyloid may be tightly regulated by GAGs and other amyloid co-factors in vivo, depending on EGCG bioavailability.