Nuclear pore permeability and fluid flow are modulated by its dilation state

Area of Science:

• Cell Biology
• Biophysics
• Environmental Physiology

Background:

• Cells must rapidly adjust cytoplasmic and nuclear volumes in response to changing environmental conditions.
• The slime mold Dictyostelium discoideum exhibits remarkable tolerance to osmotic stress, making it an ideal model organism.
• Nuclear pore complexes (NPCs) are critical gateways for nucleocytoplasmic transport, but their role in volume adaptation is less understood.

Purpose of the Study:

• To investigate the role of nuclear pore complexes (NPCs) in nuclear volume adaptation and mechanical stress relief in Dictyostelium discoideum.
• To quantify fluid flow across NPCs and understand its contribution to nucleocytosolic transport under varying osmolarity.

Main Methods:

• Utilized Dictyostelium discoideum's unique properties to quantify fluid flow across NPCs.
• Applied mathematical hydrodynamics concepts to model nucleocytosolic flow as a pressure-dependent porous flow.
• Investigated the effect of viral NPC blockage on nucleocytosolic flow rates.

Main Results:

• Dictyostelium discoideum possesses an elaborate NPC structure that influences nucleocytosolic flow permeability.
• NPC dilation state directly affects permeability for nucleocytosolic flow, conceptualized as pressure-dependent porous flow.
• Viral blockage of NPCs significantly reduced nucleocytosolic flow, highlighting NPCs' role in fluid transport.

Conclusions:

• NPCs play a vital role in regulating nucleocytosolic fluid flow, enabling nuclear volume adaptation to environmental changes.
• The pressure-dependent porous flow mechanism through NPCs is distinct from canonical nucleocytoplasmic transport.
• Findings are relevant to biological processes involving rapid nuclear size adaptation, such as cancer metastasis and cell migration.