Nucleocytoplasmic shuttling of cytoskeletal proteins : molecular mechanism and biological significance

在这项研究中，我们专注于细胞骨架和细胞核之间的沟通，这是通过动态穿梭的细胞骨架成分进入细胞核。核孔复合物（NPC）是核质分子转运的疏水选择性门，使小分子（~ 40 kDa）和核转运受体（如：例如，在一个实施例中，输入和输出）通过核膜。然而，NPC的详细选择性性质仍然未知。首先，我们证明了几种细胞骨架蛋白，如血影蛋白和辅肌动蛋白的核质穿梭的Leptomycin B，CRM 1依赖性核输出的选择性抑制剂处理的细胞的免疫染色。共沉淀和定量PCR分析揭示了它们在基因表达等基本核功能中的作用。使用毛地黄皂苷处理的细胞质耗尽细胞的体外核转运试验清楚地显示了它们自发迁移到细胞核中的有趣特性。由于这些蛋白质在其3D结构中具有特征性的两亲性基序，因此推测该两亲性基序在通过孔的疏水屏障的分子通道中起重要作用。表面疏水性测量

In this study we focused on the communication between cytoskeleton and the nucleus, which is achieved by the dynamic shuttling of cytoskeletal components into the nucleus. Nuclear pore complex(NPC) serves as a hydrophobic selective gate of nucleocytoplasmic molecular transport, enabling small molecules(~ 40kDa) and nuclear transport receptors(e. g., importins and exportins) to pass through the nuclear membrane. However, the detailed selectivity property of NPC still remained unknown. First, we demonstrated the nucleocytoplasmic shuttling of several cytoskeletal proteins such as spectrin and actinin by immunostaining of cells treated with Leptomycin B, a selective inhibitor for CRM1-dependent nuclear export. Co-precipitation and quantitative PCR assays revealed their role in fundamental nuclear functions such as gene expression. In vitro nuclear transport assay using digitonin-treated cytoplasm-depleted cells clearly showed their interesting property to spontaneously migrate into the nucleus. Because these proteins possess a characteristic amphiphilic motif in their 3D structure, it was speculated that this amphiphilic motif plays an important role in the molecular passage through the hydrophobic barrier of the pore. Surface hydrophobicity measurement by using