Nuclear envelope herniations (blebs) containing FG-nucleoporins and ubiquitin are the phenotypic hallmark of Torsin ATPase manipulation. Both the dynamics of blebbing and the connection to nuclear pore biogenesis remain poorly understood. We employ a proteomics-based approach to identify myeloid leukemia factor 2 (MLF2) as a luminal component of the bleb. Using an MLF2-based live-cell imaging platform, we demonstrate that nuclear envelope blebbing occurs rapidly and synchronously immediately after nuclear envelope reformation during mitosis. Bleb formation is independent of ubiquitin conjugation within the bleb, but strictly dependent on POM121, a transmembrane nucleoporin essential for interphase nuclear pore biogenesis. Nup358, a late marker for interphase nuclear pore complex (NPC) biogenesis, is underrepresented relative to FG-nucleoporins in nuclear envelopes of Torsin-deficient cells. The kinetics of bleb formation, its dependence on POM121, and a reduction of mature NPCs in Torsin-deficient cells lead us to conclude that the hallmark phenotype of Torsin manipulation represents aberrant NPC intermediates.

中文翻译：

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Torsin ATPase 缺乏导致核孔生物合成和 MLF2 隔离缺陷

含有 FG-核孔蛋白和泛素的核膜突出（泡）是 Torsin ATP 酶操作的表型标志。起泡的动力学以及与核孔生物发生的联系仍然知之甚少。我们采用基于蛋白质组学的方法来鉴定髓系白血病因子 2 (MLF2) 作为泡的管腔成分。使用基于 MLF2 的活细胞成像平台，我们证明了有丝分裂期间核膜重构后立即快速同步地发生核膜起泡。泡形成独立于泡内的泛素结合，但严格依赖于 POM121，POM121 是间期核孔生物发生所必需的跨膜核孔蛋白。Nup358 是间期核孔复合体 (NPC) 生物发生的晚期标记物，在 Torsin 缺陷细胞的核被膜中相对于 FG 核孔蛋白而言代表性不足。泡形成的动力学、其对 POM121 的依赖性以及 Torsin 缺陷细胞中成熟 NPC 的减少使我们得出结论，Torsin 操作的标志性表型代表了异常的 NPC 中间体。