Roles of Nup133, Nup153 and membrane fenestrations in assembly of the nuclear pore complex at the end of mitosis

Abstract

Reassembly of the nuclear pore complex (NPC) at the end of mitosis is an important event for eukaryotic nuclear function. In this study, we examined the dynamic behaviors of the endoplasmic reticulum (ER) by “Live CLEM” imaging. In metaphase, numerous fenestrations on the ER membrane were observed around chromosomes. In telophase, these fenestrations became filled at the region attached to chromosomes, whereas they remained open at the region unattached to chromosomes, suggesting that NPC assembly takes place at fenestrations on the membrane. To determine the roles of nucleoporins in postmitotic NPC formation, we used artificial beads conjugated with anti‐GFP antibody, which captures GFP‐fused proteins on the beads when incorporated into cells. Live CLEM imaging of telophase cells containing Nup133‐coated beads or Nup153‐coated beads showed that Nup133 and Nup153, as the sole effector molecules, assembled the NPC‐like structure on the membrane fenestrations. Indirect immunofluorescence staining of the Nup133‐coated beads showed that Nup133 effectively assembled Nup107 and ELYS, whereas minimal assembly of Nup98 and Nup62 was observed; the Nup153‐coated bead effectively assembled Nup98, Nup62 and Pom121, but assembled neither Nup107 nor ELYS. Our results suggest that Nup133 and Nup153 play different roles in assembling the NPC on membrane fenestrations.

Dunking into the Lipid Bilayer: How Direct Membrane Binding of Nucleoporins Can Contribute to Nuclear Pore Complex Structure and Assembly

“…In the absence of these restrains, the ER tubule localization of the Nup133-ALPS is lost [ 47 ]. Interestingly, when anti-GFP antibody coated beads were injected into GFP-Nup133 expressing HeLa cells, which generate GFP-Nup133 coated beads in these cells, nuclear envelope-like membrane structures formed on these beads [ 49 ]. Whether this is due to Nup133 membrane binding capabilities and especially the ALPS motif or mediated by other factors, e.g., other nucleoporins of the Y-complex binding to Nup133, remains open.…”

Partial deletion of chromosome 6p causing developmental delay and mild dysmorphisms in a child: molecular and developmental investigation and literature search

“…The NUP153 gene (OMIM #603,948) encodes nucleoporin 153, a protein of the nucleoporin family. Nucleoproteins are the components of nuclear pore complexes (NPCs): these are membrane-embedded channels which mediate nuclear transport across the nuclear envelope [30]. Apart from their role as constituents of NPC components, nucleoporins have recently emerged as potential regulators of chromatin organization and transcription.…”

Mitotic disassembly and reassembly of nuclear pore complexes

“…NPC assembly in the non-core region: a pre-pore in the membrane? Correlative 3D EM reconstructions indicate that the nuclear membrane of the non-core regions may originate from highly fenestrated ER sheets that are attracted to chromatin and contain holes that shrink but do not fully close [58,68]. Protein densities interpreted as NPC precursors appear in the openings and dilate radially to progress to fully assembled NPCs [58].…”