Actomyosin pulls to advance the nucleus in a migrating tissue cell

Area of Science:

• Cell Biology
• Biophysics
• Cytoskeletal Dynamics

Background:

• The forces driving nuclear translocation in migrating cells are not fully understood.
• Previous research suggested actomyosin or microtubule motor involvement.

Purpose of the Study:

• To elucidate the mechanisms of nuclear movement in migrating cells.
• To identify the specific cytoskeletal components and forces responsible for nuclear translocation.

Main Methods:

• Utilized isolated migrating cells and photoactivation of Rac1 to induce lamellipodium formation.
• Investigated nuclear movement by observing cell behavior and applying microneedle pulling.
• Employed KASH overexpression to disrupt nuclear-cytoskeletal linkages.

Main Results:

• Nuclear forward motion occurred without trailing-edge detachment, requiring nuclear-cytoskeletal linkages and myosin activity.
• Microtubules were found to stabilize nuclear position but were not essential for translocation.
• Decoupling the nucleus via KASH overexpression reduced trailing-edge detachment frequency.

Conclusions:

• Nuclear movement in crawling fibroblasts is driven by cytoskeletal linkages and myosin.
• Forces can potentially be transmitted through the nucleus from the cell front to rear.
• Microtubules play a modulatory role, not a primary role, in nuclear translocation during migration.