Department of Biological Sciences, Southern Methodist University, Dallas, Texas, United States of America.
Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America.
PLoS One. 2021 Apr 26;16(4):e0250371. doi: 10.1371/journal.pone.0250371. eCollection 2021.
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.
P-糖蛋白（P-gp）是血脑屏障（BBB）中一种重要的膜转运蛋白，与阿尔茨海默病（AD）有关。然而，之前关于 P-gp 直接转运与阿尔茨海默病相关的淀粉样β（Aβ）蛋白的能力的研究结果相互矛盾。在这里，我们使用分子动力学（MD）模拟、细胞培养中的转运底物积累研究和生化活性测定来表明 P-gp 能够主动转运 Aβ。我们观察到 P-gp 在假定的催化循环的显式 MD 模拟中转运 Aβ40 和 Aβ42 单体。在过表达 P-gp 的细胞的体外测定中，我们观察到在 Tariquidar（一种有效的 P-gp 抑制剂）存在的情况下，荧光标记的 Aβ42 的积累增加。我们还表明 Aβ42 刺激了在纳米盘中分离的 P-gp 的 ATP 水解活性。我们的发现扩展了 P-gp 的底物谱，并表明 P-gp 可能有助于 AD 的发病和进展。
