Nuclear side conformational changes in the nuclear pore complex following calcium release from the nuclear membrane.
Nuclear side conformational changes in the nuclear pore complex following calcium release from the nuclear membrane.
复制标题
钙从核膜释放后，核孔复合物的核侧构象发生变化。
DOI：
10.1088/1478-3967/1/2/008
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Dunn,RobertC
中科院分区：
文献类型：
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作者：
Mooren,OliviaL;Erickson,ElizabethS;Moore-Nichols,David;Dunn,RobertC
研究了核孔复合体(NPC)结构的变化，改变了位于共同形成核膜的两层脂双层之间的脑池钙水平。由于NPC是唯一已知的穿过核膜的通道，所以它在核质运输中起着核心作用。因此，为了完全理解这些复杂分子的功能，理解可能影响这种运输或改变与NPC的货物相互作用的构象变化的起源是必要的。在以前对核膜胞质侧的研究中，在鼻咽癌的毛孔中观察到一个中心团块，其位置对脑池中的钙水平很敏感。在这里，我们报告了原子力显微镜(AFM)对包膜核侧的测量，这也揭示了鼻咽癌构象状态下的脑池钙依赖。在单个核孔水平上进行的这些测量显示，在用位于核膜中的钙通道(三磷酸肌醇1，4，5-三磷酸(IP3)受体)的特异性激动剂腺磷脂A处理后，中央质量块向膜的核侧移动。我们进一步证明，这些构象变化是在缺乏篮子结构的核孔中观察到的，而在蛋白酶抑制剂存在的情况下制备的样品保留了篮子，并阻止了通道的AFM测量。虽然这些测量无法区分中心质量是货物还是NPC的一个组成部分，但其与脑池钙水平的剂量依赖性移位确实表明与运输或与NPC的货物相互作用的变化有关。结合之前在核膜细胞质一侧所做的测量，这些研究反对中心质量的活塞式位移，而是提出了更复杂的机制。一种可能性涉及脑池钙释放后鼻咽癌环相互协调塌陷，从而导致明显的鼻咽癌两侧中央肿块的出现。
Changes in nuclear pore complex (NPC) structure are studied following treatments modifying the cisternal calcium levels located between the two lipid bilayers that together form the nuclear envelope. Since the NPC forms the only known passageway across the nuclear envelope, it plays a central role in nucleocytoplasmic transport. Understanding the origin of conformational changes that may affect this trafficking or modify cargo interactions with the NPC is, therefore, necessary to completely understand the function of these complex molecules. In previous studies on the cytoplasmic side of the nuclear envelope, a central mass was observed in the pore of the NPC and its location was shown to be sensitive to the cisternal calcium levels. Here we report atomic force microscopy (AFM) measurements on the nuclear side of the envelope, which also reveal a cisternal calcium dependence in the conformational state of the NPC. These measurements, made at the single nuclear pore level, reveal a displacement of the central mass towards the nuclear side of the membrane following treatments with adenophostin A, a specific agonist of calcium channels (inositol 1, 4, 5-trisphosphate (IP 3) receptors) located in the nuclear envelope. We further demonstrate that these conformational changes are observed in nuclear pores lacking the basket structure while samples prepared in the presence of protease inhibitors retain baskets and block AFM measurements of the channel. While these measurements are unable to distinguish whether the central mass is cargo or an integral component of the NPC, its dose-dependent displacement with cisternal calcium levels does suggest links to transport or to changes in cargo interactions with the NPC. Taken together with previous measurements done on the cytoplasmic side of the nuclear envelope, these studies argue against a piston-like displacement of the central mass and instead suggest a more complicated mechanism. One possibility involves a concerted collapse of the NPC rings towards one another following cisternal calcium release, thus leading to the apparent emergence of the central mass from each side of the NPC.