Selective Aster inhibitors distinguish vesicular and nonvesicular sterol transport mechanisms.
Selective Aster inhibitors distinguish vesicular and nonvesicular sterol transport mechanisms.
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选择性 Aster 抑制剂区分囊泡和非囊泡甾醇转运机制。
DOI：
10.1073/pnas.2024149118
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发表时间：
2021
影响因子：
11.1
通讯作者：
Tontonoz,Peter
中科院分区：
文献类型：
--
作者：
Xiao,Xu;Kim,Youngjae;Romartinez-Alonso,Beatriz;Sirvydis,Kristupas;Ory,DanielS;Schwabe,JohnWR;Jung,MichaelE;Tontonoz,Peter
Aster蛋白（由Gramd 1a-c基因编码）含有结构上类似于START结构域的配体结合折叠，并介导非囊泡质膜（PM）至内质网（ER）的胆固醇转运。为了开发Aster的小分子调节剂，我们鉴定了20α-羟基胆固醇（HC）和U18666 A作为先导化合物。不幸的是，20α-HC和U18666 A都靶向其他固醇稳态蛋白，限制了它们的用途。20α-HC抑制固醇调节元件结合蛋白2（SREBP 2）加工，U18666 A是囊泡运输蛋白尼曼-匹克C1（NPC 1）的抑制剂。为了开发高效、选择性的Aster抑制剂，我们对20α-HC和U18666 A进行了修饰，合成了一系列化合物。其中，具有比20α-HC更长的侧链的AI（Aster inhibitor）-11选择性地结合Aster-C。Aster-C与AI-11复合的晶体结构表明，控制结合腔的环中的序列和柔性差异可能是Aster-C的配体特异性的原因。我们进一步鉴定了U18666 A类似物AI-3d作为所有三种Aster蛋白的有效抑制剂。AI-3d阻断Aster在体外和细胞中结合和转移胆固醇的能力。重要的是，AI-3d还抑制低密度脂蛋白（LDL）胆固醇向ER的移动，尽管AI-3d不阻断NPC 1。这一发现将非囊泡Aster途径定位在LDL胆固醇向ER移动中的NPC 1依赖性囊泡转运的下游。选择性紫菀抑制剂代表有用的化学工具，以区分囊泡和非囊泡固醇运输机制在哺乳动物细胞。
The Aster proteins (encoded by theGramd1a-cgenes) contain a ligand-binding fold structurally similar to a START domain and mediate nonvesicular plasma membrane (PM) to endoplasmic reticulum (ER) cholesterol transport. In an effort to develop small molecule modulators of Asters, we identified 20α-hydroxycholesterol (HC) and U18666A as lead compounds. Unfortunately, both 20α-HC and U18666A target other sterol homeostatic proteins, limiting their utility. 20α-HC inhibits sterol regulatory element-binding protein 2 (SREBP2) processing, and U18666A is an inhibitor of the vesicular trafficking protein Niemann–Pick C1 (NPC1). To develop potent and selective Aster inhibitors, we synthesized a series of compounds by modifying 20α-HC and U18666A. Among these, AI (Aster inhibitor)-1l, which has a longer side chain than 20α-HC, selectively bound to Aster-C. The crystal structure of Aster-C in complex with AI-1l suggests that sequence and flexibility differences in the loop that gates the binding cavity may account for the ligand specificity for Aster C. We further identified the U18666A analog AI-3d as a potent inhibitor of all three Aster proteins. AI-3d blocks the ability of Asters to bind and transfer cholesterol in vitro and in cells. Importantly, AI-3d also inhibits the movement of low-density lipoprotein (LDL) cholesterol to the ER, although AI-3d does not block NPC1. This finding positions the nonvesicular Aster pathway downstream of NPC1-dependent vesicular transport in the movement of LDL cholesterol to the ER. Selective Aster inhibitors represent useful chemical tools to distinguish vesicular and nonvesicular sterol transport mechanisms in mammalian cells.