M.E. Mueller Institute for Structural Biology, Biozentrum, University of Basel, Switzerland.
Nucleus. 2011 Sep-Oct;2(5):500-9. doi: 10.4161/nucl.2.5.17913. Epub 2011 Sep 1.
The nuclear envelope (NE) is a double membrane physical barrier, which separates the nucleus from the cytoplasm. Underlying the NE are the nuclear lamins, which in combination with inner nuclear membrane proteins form the lamina. The lamina is crucial for maintaining the structural integrity of the nucleus and for positioning of nuclear pore complexes (NPCs) within the NE. The nucleoporin Nup153 has previously been reported to bind to B-type lamins. However, the specificity of this interaction is not well established. Here we show that Nup153 exhibits multiple binding sites for A- and B-type lamins. Using GST-pull down assays, we found that both the N-terminal domain of Nup153 and its C terminus associate with the Ig-fold domain of A- and B-type lamins. By employing purified Nup153 and lamin proteins in blot overlay assays we revealed that both the N-terminal and the C-terminal domain of Nup153 are directly interacting with the lamins. Moreover, we provide evidence that mutations in the lamin A Ig-fold domain selectively affect Nup153-binding, suggesting that Nup153 may play a role in lamin-associated diseases, known as laminopathies. Together our results indicate a far more intricate interplay between Nup153 and nuclear lamins than previously accepted.
核膜（NE）是一种双层物理屏障，将细胞核与细胞质分隔开来。在核膜下是核纤层，它与内核膜蛋白结合形成核层。核层对于维持细胞核的结构完整性和核孔复合物（NPC）在核膜中的定位至关重要。核孔蛋白 Nup153 先前已被报道与 B 型核纤层结合。然而，这种相互作用的特异性尚未得到很好的确定。在这里，我们表明 Nup153 对 A 型和 B 型核纤层表现出多个结合位点。通过 GST 下拉测定，我们发现 Nup153 的 N 端结构域及其 C 端与 A 型和 B 型核纤层的 Ig 折叠结构域都结合。通过在印迹覆盖测定中使用纯化的 Nup153 和核纤层蛋白，我们揭示了 Nup153 的 N 端和 C 端结构域都与核纤层直接相互作用。此外，我们提供的证据表明，核纤层 A Ig 折叠结构域的突变选择性地影响 Nup153 的结合，这表明 Nup153 可能在核纤层相关疾病（称为核纤层病）中发挥作用。总之，我们的结果表明，Nup153 与核纤层之间的相互作用远比之前认为的复杂得多。
