Iwamoto Masaaki, Osakada Hiroko, Mori Chie, Fukuda Yasuhiro, Nagao Koji, Obuse Chikashi, Hiraoka Yasushi, Haraguchi Tokuko
Advanced ICT Research Institute, National Institute of Information and Communications Technology (NICT), Kobe 651-2492, Japan.
Graduate School of Agriculture, Tohoku University, Osaki, Miyagi 989-6711, Japan.
J Cell Sci. 2017 May 15;130(10):1822-1834. doi: 10.1242/jcs.199398. Epub 2017 Apr 6.
The nuclear pore complex (NPC), a gateway for nucleocytoplasmic trafficking, is composed of ∼30 different proteins called nucleoporins. It remains unknown whether the NPCs within a species are homogeneous or vary depending on the cell type or physiological condition. Here, we present evidence for compositionally distinct NPCs that form within a single cell in a binucleated ciliate. In , each cell contains both a transcriptionally active macronucleus (MAC) and a germline micronucleus (MIC). By combining analysis, mass spectrometry analysis for immuno-isolated proteins and subcellular localization analysis of GFP-fused proteins, we identified numerous novel components of MAC and MIC NPCs. Core members of the Nup107-Nup160 scaffold complex were enriched in MIC NPCs. Strikingly, two paralogs of Nup214 and of Nup153 localized exclusively to either the MAC or MIC NPCs. Furthermore, the transmembrane components Pom121 and Pom82 localize exclusively to MAC and MIC NPCs, respectively. Our results argue that functional nuclear dimorphism in ciliates is likely to depend on the compositional and structural specificity of NPCs.
核孔复合体（NPC）是核质运输的通道，由约30种不同的蛋白质组成，这些蛋白质被称为核孔蛋白。一个物种内的NPC是同质的，还是会因细胞类型或生理状态而异，目前尚不清楚。在这里，我们提供了证据，证明在双核纤毛虫的单个细胞内形成了组成不同的NPC。在 中，每个细胞都包含一个转录活跃的大核（MAC）和一个种系小核（MIC）。通过结合 分析、免疫分离蛋白的质谱分析以及绿色荧光蛋白融合蛋白的亚细胞定位分析，我们鉴定出了MAC和MIC NPC的许多新成分。Nup107-Nup160支架复合体的核心成员在MIC NPC中富集。引人注目的是，Nup214和Nup153的两个旁系同源物分别仅定位于MAC或MIC NPC。此外，跨膜成分Pom121和Pom82分别仅定位于MAC和MIC NPC。我们的结果表明，纤毛虫中的功能性核二态性可能取决于NPC的组成和结构特异性。
