Mechanisms for assembly/disassembly of the nuclear envelope

核膜在有丝分裂开始时解体，分散在细胞质中，并在末期重新组装到子细胞中。尽管最近的一项研究表明VCP参与了核膜的组装，但VCP的功能尚不完全清楚。今年取得了以下进展：(I)VCP-SVIP复合体的鉴定：VCP是一种伴侣样ATPase，与Ufd1p合作，参与核膜组装。我们鉴定了一种新的VCP适配子，命名为SVIP(Small VCP-Interaction Protein)，它形成了一个不同于VCP-Ufd1p的复合体。(Ii)Synaxin 18结合蛋白的鉴定：Synaxin 18位于内质网，与外核膜相邻。我们证明了Synaxin 18与hZW10和Rint-1形成了一个复合体，这两个基因都参与了细胞周期检查点。BNIP1是一种促凋亡蛋白，它还与Synaxin 18有关。这些结果表明，Synaxin 18复合体不仅在膜融合中发挥作用，而且在细胞周期和细胞凋亡中也发挥作用。(Iii)核VCP样蛋白NVL的分析：NVL的作用尚不清楚。我们发现NVL定位于核仁中，并与RNA解旋酶Mtr4p相互作用。Mtr4p与NVL的共表达促进了Mtr4p的核仁定位，提示NVL是Mtr4p的伴侣样蛋白。

The nuclear envelope is disassembled at the onset of mitosis, dispersed throughout the cytoplasm, and is reassembled in daughter cells at telophase. Although a recent study has demonstrated that VCP participates in the assembly of the nuclear envelope, the function of VCP is not fully understood. The following progresses have been achieved this year.(i) Identification of the VCP-SVIP complex: VCP is a chaperone-like ATPase and, in cooperation with Ufd1p, participates in nuclear envelope assembly. We identified a new adaptor for VCP named SVIP (small VCP-interacting protein) that forms a complex distinct from the VCP-Ufd1p.(ii) Identification of syntaxin 18-binding proteins: Syntaxin 18 is located in the endoplasmic reticulum, which is contiguous with the outer nuclear membrane. We demonstrated that syntaxin 18 forms a complex with hZW10 and RINT-1, both of which are involved in cell cycle checkpoints. BNIP1, a pro-apoptotic protein, also associates with syntaxin 18. These results raise the possibility that syntaxin 18 complex plays a role not only in membrane fusion but also in cell cycle and apoptosis.(iii) Analysis of a nuclear VCP-like protein, NVL: The role of NVL, a nuclear VCP-like protein, remains unclear. We found that NVL is localized in nucleoli and interacts with an RNA helicase, Mtr4p. Co-expression of Mtr4p with NVL facilitated the nucleolar-localization of Mtr4p, suggesting that NVL is a chaperone-like protein for Mtr4p.