P-glycoprotein (P-gp) is a critical membrane transporter in the blood brain barrier (BBB) and is implicated in Alzheimer's disease (AD). However, previous studies on the ability of P-gp to directly transport the Alzheimer's associated amyloid-β (Aβ) protein have produced contradictory results. Here we use molecular dynamics (MD) simulations, transport substrate accumulation studies in cell culture, and biochemical activity assays to show that P-gp actively transports Aβ. We observed transport of Aβ40 and Aβ42 monomers by P-gp in explicit MD simulations of a putative catalytic cycle. In in vitro assays with P-gp overexpressing cells, we observed enhanced accumulation of fluorescently labeled Aβ42 in the presence of Tariquidar, a potent P-gp inhibitor. We also showed that Aβ42 stimulated the ATP hydrolysis activity of isolated P-gp in nanodiscs. Our findings expand the substrate profile of P-gp, and suggest that P-gp may contribute to the onset and progression of AD.

中文翻译：

---

P-糖蛋白催化的阿兹海默症相关淀粉样蛋白β的转运

P-糖蛋白（P-gp）是血脑屏障（BBB）中的关键膜转运蛋白，与阿尔茨海默氏病（AD）有关。但是，先前有关P-gp直接转运阿尔茨海默氏症相关淀粉样β蛋白（Aβ）蛋白能力的研究产生了矛盾的结果。在这里，我们使用分子动力学（MD）模拟，细胞培养中转运底物积累的研究以及生化活性测定法来证明P-gp主动转运Aβ。我们在推定的催化循环的明确MD模拟中观察到P-gp转运Aβ40和Aβ42单体。在使用过表达P-gp的细胞进行的体外分析中，我们观察到在有效的P-gp抑制剂Tariquidar存在下，荧光标记的Aβ42的积累增强了。我们还表明，Aβ42刺激了纳米圆盘中分离的P-gp的ATP水解活性。我们的发现扩大了P-gp的底物谱，并暗示P-gp可能有助于AD的发作和发展。