Dawson T Renee, Lazarus Michelle D, Hetzer Martin W, Wente Susan R
Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
J Cell Biol. 2009 Mar 9;184(5):659-75. doi: 10.1083/jcb.200806174.
Nucleocytoplasmic transport occurs exclusively through nuclear pore complexes (NPCs) embedded in pores formed by inner and outer nuclear membrane fusion. The mechanism for de novo pore and NPC biogenesis remains unclear. Reticulons (RTNs) and Yop1/DP1 are conserved membrane protein families required to form and maintain the tubular endoplasmic reticulum (ER) and the postmitotic nuclear envelope. In this study, we report that members of the RTN and Yop1/DP1 families are required for nuclear pore formation. Analysis of Saccharomyces cerevisiae prp20-G282S and nup133 Delta NPC assembly mutants revealed perturbations in Rtn1-green fluorescent protein (GFP) and Yop1-GFP ER distribution and colocalization to NPC clusters. Combined deletion of RTN1 and YOP1 resulted in NPC clustering, nuclear import defects, and synthetic lethality with the additional absence of Pom34, Pom152, and Nup84 subcomplex members. We tested for a direct role in NPC biogenesis using Xenopus laevis in vitro assays and found that anti-Rtn4a antibodies specifically inhibited de novo nuclear pore formation. We hypothesize that these ER membrane-bending proteins mediate early NPC assembly steps.
核质运输仅通过嵌入由内核膜和外核膜融合形成的孔中的核孔复合体（NPC）进行。从头形成孔和NPC的机制仍不清楚。网织蛋白（RTN）和Yop1/DP1是形成和维持管状内质网（ER）以及有丝分裂后核膜所需的保守膜蛋白家族。在本研究中，我们报告RTN和Yop1/DP1家族成员是核孔形成所必需的。对酿酒酵母prp20 - G282S和nup133 Delta NPC组装突变体的分析揭示了Rtn1 - 绿色荧光蛋白（GFP）和Yop1 - GFP在内质网分布以及与NPC簇共定位方面的扰动。RTN1和YOP1的联合缺失导致NPC聚集、核输入缺陷以及在额外缺失Pom34、Pom152和Nup84亚复合体成员时出现合成致死性。我们使用非洲爪蟾体外试验测试了其在NPC生物发生中的直接作用，发现抗Rtn4a抗体特异性抑制了从头核孔形成。我们推测这些内质网膜弯曲蛋白介导了NPC组装的早期步骤。
