Mitotic Disassembly of Nuclear Pore Complexes Involves CDK1- and PLK1-Mediated Phosphorylation of Key Interconnecting Nucleoporins

Abstract

SummaryDuring interphase, the nuclear envelope (NE) serves as a selective barrier between cytosol and nucleoplasm. When vertebrate cells enter mitosis, the NE is dismantled in the process of nuclear envelope breakdown (NEBD). Disassembly of nuclear pore complexes (NPCs) is a key aspect of NEBD, required for NE permeabilization and formation of a cytoplasmic mitotic spindle. Here, we show that both CDK1 and polo-like kinase 1 (PLK1) support mitotic NPC disintegration by hyperphosphorylation of Nup98, the gatekeeper nucleoporin, and Nup53, a central nucleoporin linking the inner NPC scaffold to the pore membrane. Multisite phosphorylation of Nup53 critically contributes to its liberation from its partner nucleoporins, including the pore membrane protein NDC1. Initial steps of NPC disassembly in semi-permeabilized cells can be reconstituted by a cocktail of mitotic kinases including cyclinB-CDK1, NIMA, and PLK1, suggesting that the unzipping of nucleoporin interactions by protein phosphorylation is an important principle underlying mitotic NE permeabilization.

Cyclin B1-Cdk1 facilitates MAD1 release from the nuclear pore to ensure a robust spindle checkpoint

“…The role of Cdk1 in NPC disassembly has been most clearly shown in studies using a powerful in vitro system (Linder et al, 2017; Marino et al, 2014). These studies have implicated the Plk1 and Nek kinases working in coordination with Cdk1 to phosphorylate the core NPC components Nup98 and Nup53.…”

“…To ensure that cells remain in mitosis, cyclin B1-Cdk1 phosphorylates and activates the Greatwall protein kinase, which generates an inhibitor of the PP2A-B55 phosphatase that antagonizes cyclin B1-Cdk1 in interphase (Castilho et al, 2009; Gharbi-Ayachi et al, 2010; Mochida et al, 2010). In its role as the workhorse of mitosis (Nigg, 1995), cyclin B1-Cdk1 phosphorylates structural components throughout the cell including the nuclear lamins (Heald and McKeon, 1990; Peter et al, 1990), nuclear pore components (Linder et al, 2017), condensins (Hirano, 2012), and cytoskeletal regulators such as the Rho Guanine nucleotide exchange factor ECT2 (Tatsumoto et al, 1999). Microtubule motors, nonmotor microtubule-associated proteins, endoplasmic reticulum, and Golgi apparatus components are also extensively phosphorylated by cyclin B1-Cdk1 (Champion et al, 2017; Wieser and Pines, 2015).…”

Interactions between non‐structured domains of FG‐ and non‐FG‐nucleoporins coordinate the ordered assembly of the nuclear pore complex in mitosis

“…1971-1983), 20 which recruits early assembling Nups such as the Nup107-160 complex and Nups98 and 153. It could be intriguing to investigate how phosphorylation/dephosphorylation of Nups (such as the Nup107-160 complex, 29 Nup35, 30 and Nup98 31 is involved in the regulation of Nup reassembly. Therefore, it is plausible that the C-terminal domain of ELYS functions as a platform for the successive assembly of FG-Nups via hydrophobic interactions among IDRs.…”

C. elegans pronuclei fuse after fertilization through a novel membrane structure

“…During mitosis in metazoans, NE breakdown (NEBD) allows microtubules nucleated by cytoplasmic centrosomes to access the chromosomes. NEBD requires the activity of various kinases, including cyclin-dependent kinase 1 and Polo-like kinase 1, which drive the disassembly of the NPCs and nuclear lamina (Heald and McKeon, 1990; Laurell et al, 2011; Rahman et al, 2015; Martino et al, 2017; Linder et al, 2017). However, in many cell types, the membranes of the NE persist and become highly fenestrated such that they exclude organelles but no longer pose a diffusion barrier (Ellenberg et al, 1997; Yang et al, 1997; Hepler and Wolniak, 1984; Schweizer et al, 2015; Luckner and Wanner, 2018).…”