Selective NPC Removal Drives Nuclear Envelope Fenestration and Nuclear Division in the Fission Yeast

Abstract

An important question in cell biology is how cellular organelles partition during cell division. In organisms undergoing closed mitosis, the elongation of an intranuclear spindle drives nuclear division, generating two identically sized nuclei. However, how the site of nuclear division is determined, and the underlying mechanism driving nuclear envelope (NE) fission remains largely unknown. Here, using the fission yeast, we show that during anaphase the microtubule bundler Ase1/PRC1 at the spindle midzone is required for the local concentration of nuclear pore complexes (NPCs) in the region of the NE in contact with the central spindle. As the spindle elongates, components of these NPCs are sequentially eliminated and this is accompanied by the local remodeling of the NE. These two events require importin α and lead to the eventual removal of NPCs and NE fenestration, which drives nuclear division. Finally, after nuclear division the mitotic spindle is fully disassembled. Thus, the central spindle acts as a spatial cue by directing the accumulation of NPCs, and NPC clustering and removal promotes NE fenestration and fission. These results suggest an evolutionary link with the mechanism of NPC removal from the NE and initial events of NE breakdown of metazoans