Nuclear Pores Assemble from Nucleoporin Condensates During Oogenesis

Area of Science:

• Cell Biology
• Developmental Biology
• Molecular Biology

Background:

• Nuclear pore complexes (NPCs) mediate transport between the nucleus and cytoplasm.
• NPC assembly is traditionally understood to occur during mitosis or interphase.
• In gametes and embryonic cells, NPCs are found in annulate lamellae (AL), but the biogenesis mechanism is unclear.

Purpose of the Study:

• To elucidate the mechanism of NPC biogenesis at cytoplasmic membranes.
• To investigate NPC assembly during Drosophila oogenesis.

Main Methods:

• Observation of nucleoporin condensation into precursor granules.
• Analysis of Nup358's role in NPC assembly platforms.
• Investigation of mRNA localization and translation dependence.
• Study of microtubule-dependent transport, Ran GTPase, and nuclear transport receptors.

Main Results:

• Nucleoporins condense into distinct precursor granules that assemble into NPCs.
• Nup358 is crucial, forming assembly platforms with its mRNA localized to the surface in a translation-dependent manner.
• NPC biogenesis in oocytes is regulated by microtubule transport, Ran, and nuclear transport receptors.
• A non-canonical NPC assembly pathway occurs away from the nucleus, involving nucleoporin condensates during cell cycle arrest.

Conclusions:

• A novel mechanism for NPC biogenesis at cytoplasmic membranes has been identified.
• This pathway relies on nucleoporin condensates and occurs independently of the nucleus.
• Findings provide insights into NPC storage and assembly in early development and under specific cellular conditions.