Regulated changes in material properties underlie centrosome disassembly during mitotic exit

Area of Science:

• Cell Biology
• Biophysics
• Molecular Biology

Background:

• Centrosomes are critical for chromosome segregation during mitosis, resisting microtubule forces.
• During mitotic exit, centrosomes are intentionally disassembled by microtubule forces.
• The molecular mechanisms governing centrosome mechanical properties throughout the cell cycle are largely unknown.

Purpose of the Study:

• To investigate the molecular basis of centrosome strength and ductility.
• To understand how centrosome mechanical properties change during the cell cycle.
• To determine how these properties relate to centrosome disassembly.

Main Methods:

• Utilized optically induced flow perturbations in C. elegans embryos.
• Measured changes in centrosome mechanical properties (strength and ductility).
• Investigated the roles of specific proteins (PLK-1, SPD-2) and phosphatases (PP2A) in vitro and in vivo.

Main Results:

• Centrosome strength and ductility significantly decreased at anaphase onset, preceding natural disassembly.
• This mechanical weakening required PP2A phosphatase activity and correlated with PLK-1 and SPD-2 inactivation.
• In vitro experiments showed PLK-1 and SPD-2 protect centrosome scaffolds from force-induced damage.

Conclusions:

• Before anaphase, PLK-1 and SPD-2 confer strength and ductility to centrosomes, enabling resistance to microtubule forces.
• At anaphase onset, loss of PLK-1 and SPD-2 transitions centrosomes to a weak, brittle state.
• This mechanical transition facilitates force-mediated centrosome disassembly during mitotic exit.