Huang Ching-Shin, Yu Xinchao, Fordstrom Preston, Choi Kaylee, Chung Ben C, Roh Soung-Hun, Chiu Wah, Zhou Mingyue, Min Xiaoshan, Wang Zhulun
Department of Therapeutic Discovery, Amgen Research, Amgen Inc., 1120 Veterans Blvd., South San Francisco, CA 94080, USA.
Department of Cardiometabolic Disorders, Amgen Research, Amgen Inc., 1120 Veterans Blvd., South San Francisco, CA 94080, USA.
Sci Adv. 2020 Jun 19;6(25):eabb1989. doi: 10.1126/sciadv.abb1989. eCollection 2020 Jun.
The intestinal absorption of cholesterol is mediated by a multipass membrane protein, Niemann-Pick C1-Like 1 (NPC1L1), the molecular target of a cholesterol lowering therapy ezetimibe. While ezetimibe gained Food and Drug Administration approval in 2002, its mechanism of action has remained unclear. Here, we present two cryo-electron microscopy structures of NPC1L1, one in its apo form and the other complexed with ezetimibe. The apo form represents an open state in which the N-terminal domain (NTD) interacts loosely with the rest of NPC1L1, leaving the NTD central cavity accessible for cholesterol loading. The ezetimibe-bound form signifies a closed state in which the NTD rotates ~60°, creating a continuous tunnel enabling cholesterol movement into the plasma membrane. Ezetimibe blocks cholesterol transport by occluding the tunnel instead of competing with cholesterol binding. These findings provide insight into the molecular mechanisms of NPC1L1-mediated cholesterol transport and ezetimibe inhibition, paving the way for more effective therapeutic development.
胆固醇的肠道吸收由一种多次跨膜蛋白——尼曼-匹克C1样1蛋白（NPC1L1）介导，它是降胆固醇药物依泽替米贝的分子靶点。尽管依泽替米贝在2002年获得了美国食品药品监督管理局的批准，但其作用机制仍不清楚。在此，我们展示了NPC1L1的两种冷冻电镜结构，一种是无配体形式，另一种是与依泽替米贝结合的形式。无配体形式代表一种开放状态，其中N端结构域（NTD）与NPC1L1的其余部分松散相互作用，使NTD中央腔可用于胆固醇加载。依泽替米贝结合形式表示一种封闭状态，其中NTD旋转约60°，形成一个连续的通道，使胆固醇能够移动到质膜中。依泽替米贝通过阻塞通道而不是与胆固醇结合竞争来阻断胆固醇转运。这些发现为深入了解NPC1L1介导的胆固醇转运和依泽替米贝抑制的分子机制提供了线索，为更有效的治疗药物开发铺平了道路。
