Binding partner switching on microtubules and aurora-B in the mitosis to cytokinesis transition

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• The cytoskeleton undergoes major reorganization between mitosis (M phase) and cytokinesis (C phase).
• These dynamic changes necessitate extensive regulatory mechanisms.
• Understanding these regulatory shifts is crucial for comprehending cell division.

Purpose of the Study:

• To identify proteins that selectively bind to microtubules during C phase.
• To investigate the regulatory roles of kinases, particularly Aurora kinases, in C phase cytoskeleton dynamics.
• To establish a biochemical framework for understanding C phase regulation.

Main Methods:

• Comparative proteomics analysis of drug-synchronized cells in M and C phases.
• Identification of selective microtubule-binding proteins using biochemical assays.
• Assessing the impact of Aurora kinase inhibition (using VX680) on protein-microtubule interactions.
• Analyzing changes in Aurora-B binding partners between M and C phases.

Main Results:

• Identified 25 proteins with selective C phase microtubule binding, including novel partners like nucleolar and spindle-associated protein.
• Demonstrated that C phase-selective microtubule binding for many proteins depends on Aurora kinase activity.
• Revealed a dramatic switch in Aurora-B binding partners from M to C phase, identifying new partners such as PRC1, KIF4, and the anaphase-promoting complex/cyclosome.

Conclusions:

• Aurora-B kinase plays a central role in regulating the C phase cytoskeleton.
• The study provides the first broad biochemical framework for understanding C phase regulation.
• The proteomics approach is extendable to other cellular compartments and states.