Partial nuclear pore complex disassembly during closed mitosis in Aspergillus nidulans

Area of Science:

• Cell Biology
• Molecular Biology
• Genetics

Background:

• Organisms utilize closed mitosis, sequestering key proteins like tubulin and mitotic kinases within nuclei only during cell division.
• The precise regulation of this nuclear localization remains poorly understood.
• The NIMA kinase in Aspergillus nidulans interacts with nuclear pore complex (NPC) proteins and is crucial for mitotic kinase Cdk1 localization to the nucleus.

Purpose of the Study:

• To elucidate the regulatory mechanisms governing the nuclear pore complex (NPC) during closed mitosis in Aspergillus nidulans.
• To investigate the role of NIMA kinase and Cdk1 in controlling NPC dynamics during mitosis.

Main Methods:

• Microscopy to observe NPC structural changes.
• Biochemical assays to analyze protein localization and NPC function.
• Genetic manipulation to study the roles of NIMA and Cdk1 kinases.

Main Results:

• Significant structural alterations in the NPC during mitosis, with some proteins dispersing and others remaining localized.
• Altered NPC function during mitosis, affecting nuclear exclusion of An-RanGAP and localization of other proteins.
• Mitotic NPC modifications are dependent on NIMA and Cdk1 kinase activation, with NIMA playing a critical role.
• Ectopic NIMA induction triggers premature mitotic-like NPC changes during S phase.

Conclusions:

• Partial NPC disassembly, regulated by NIMA and Cdk1, represents a novel mechanism for managing closed mitosis in Aspergillus nidulans.
• Protein localization during closed mitosis may be governed by relative binding affinities, similar to open mitosis.