Spatial regulation of MCAK promotes cell polarization and focal adhesion turnover to drive robust cell migration

Area of Science:

• Cell Biology
• Molecular Biology
• Biophysics

Background:

• Asymmetric microtubule (MT) dynamics are vital for cell migration and polarization.
• Regulatory mechanisms governing MT dynamics during cell migration are not fully understood.
• Mitotic centromere-associated kinesin (MCAK) is an MT depolymerase with potential roles in cell motility.

Purpose of the Study:

• To investigate the role of MCAK in the persistent migration of RPE-1 cells.
• To elucidate how MCAK influences cell polarization, protrusion dynamics, and focal adhesion turnover.
• To understand the spatial regulation of MCAK activity in migrating cells.

Main Methods:

• MCAK knockdown using RNA interference.
• Live and fixed cell imaging to analyze cell morphology, migration, and MT dynamics.
• Assessment of membrane ruffling, cell polarization, and focal adhesion dynamics.
• Investigation of Rac1's role in relation to MCAK function.

Main Results:

• MCAK knockdown impaired cell migration speed and directionality.
• Loss of MCAK led to excessive membrane ruffling and defects in cell polarization and protrusion maintenance.
• MCAK depletion increased focal adhesion lifetime by reducing their disassembly rate.
• MCAK activity was spatially polarized, with higher activity at the trailing edge.
• Rac1 overexpression showed a dominant effect, suggesting it acts downstream or in parallel to MCAK.

Conclusions:

• A polarized distribution of MCAK activity is essential for regulating microtubule dynamics.
• This polarized activity contributes to cell polarity, centrosome positioning, and focal adhesion turnover.
• MCAK plays a critical role in facilitating robust directional cell migration.