Misassembled nuclear pore complexes (NPCs) are removed by sealing off the surrounding nuclear envelope (NE), which is conducted by the endosomal sorting complexes required for transport (ESCRT) machinery. Recruitment of ESCRT proteins to the NE is mediated by the interaction between the ESCRT member Chm7 and the inner nuclear membrane protein Heh1, which belongs to the conserved LEM family. Increased ESCRT recruitment results in excessive membrane scission at damage sites but its regulation remains poorly understood. Here, we show that Hub1-mediated alternative splicing of HEH1 pre-mRNA, resulting in production of its shorter form Heh1-S, is critical for the integrity of the NE in Saccharomyces cerevisiae. ESCRT-III mutants lacking Hub1 or Heh1-S display severe growth defects and accumulate improperly assembled NPCs. This depends on the interaction of Chm7 with the conserved MSC domain, which is only present in the longer variant Heh1-L. Heh1 variants assemble into heterodimers, and we demonstrate that a unique splice segment in Heh1-S suppresses growth defects associated with the uncontrolled interaction between Heh1-L and Chm7. Together, our findings reveal that Hub1-mediated splicing generates Heh1-S to regulate ESCRT recruitment to the NE.

This article has an associated First Person interview with the first author of the paper.

通过密封周围的核膜 (NE) 来去除错误组装的核孔复合物 (NPC)，这是由运输所需的内体分选复合物 (ESCRT) 机械进行的。ESCRT 蛋白向 NE 的募集是由 ESCRT 成员 Chm7 和内核膜蛋白 Heh1（属于保守的 LEM 家族）之间的相互作用介导的。ESCRT 募集的增加会导致损伤部位的膜过度断裂，但其调节机制仍知之甚少。在这里，我们发现 Hub1 介导的HEH1前体 mRNA 的选择性剪接，导致其较短形式 Heh1-S 的产生，对于酿酒酵母中 NE 的完整性至关重要。缺乏 Hub1 或 Heh1-S 的 ESCRT-III 突变体表现出严重的生长缺陷并积累了组装不当的 NPC。这取决于 Chm7 与保守 MSC 结构域的相互作用，该结构域仅存在于较长的变体 Heh1-L 中。Heh1 变体组装成异二聚体，我们证明 Heh1-S 中独特的剪接片段抑制了与 Heh1-L 和 Chm7 之间不受控制的相互作用相关的生长缺陷。总之，我们的研究结果表明 Hub1 介导的剪接生成 Heh1-S 来调节 ESCRT 向 NE 的募集。

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