Faculty of Science and Technology, Department of Biosciences and Informatics, Keio University, Yokohama 223-8522, Japan.
ACS Chem Biol. 2012 May 18;7(5):892-900. doi: 10.1021/cb200492h. Epub 2012 Mar 2.
Autophagy is a bulk, nonspecific protein degradation pathway that is involved in the pathogenesis of cancer and neurodegenerative disease. Here, we observed that xanthohumol (XN), a prenylated chalcone present in hops (Humulus lupulus L.) and beer, modulates autophagy. By using XN-immobilized beads, valosin-containing protein (VCP) was identified as a XN-binding protein. VCP has been reported to be an essential protein for autophagosome maturation. Using an in vitro pull down assay, we showed that XN bound directly to the N domain, which is known to mediate cofactor and substrate binding to VCP. These data indicated that XN inhibited the function of VCP, thereby allowing the impairment of autophagosome maturation and resulting in the accumulation of microtubule-associated protein 1 light chain 3-II (LC3-II). This is the first report demonstrating XN as a VCP inhibitor that binds directly to the N domain of VCP. Our finding that XN bound to and inactivated VCP not only reveals the molecular mechanism of XN-modulated autophagy but may also explain how XN exhibits various biological activities that have been reported previously.
自噬是一种大规模、非特异性的蛋白质降解途径，与癌症和神经退行性疾病的发病机制有关。在这里，我们观察到，黄腐酚（XN），一种存在于啤酒花（Humulus lupulus L.）和啤酒中的类异戊二烯查尔酮，可调节自噬。通过使用 XN 固定珠，鉴定到包含缬氨酸的蛋白（VCP）为 XN 结合蛋白。VCP 已被报道为自噬体成熟所必需的蛋白质。通过体外下拉实验，我们表明 XN 直接与已知介导 VCP 辅助因子和底物结合的 N 结构域结合。这些数据表明 XN 抑制了 VCP 的功能，从而导致自噬体成熟受损，导致微管相关蛋白 1 轻链 3-II（LC3-II）积累。这是首次报道 XN 作为一种直接与 VCP 的 N 结构域结合的 VCP 抑制剂。我们的发现表明，XN 结合并失活 VCP 不仅揭示了 XN 调节自噬的分子机制，也可能解释了 XN 如何表现出先前报道的各种生物学活性。
