Actin-Based Transport Adapts Polarity Domain Size to Local Cellular Curvature

Cells regulate intracellular structures to match their size and shape. Polarity domains, like those formed by active Rho-GTPases, vary in width depending on cell geometry. Prior research has shown that these domains scale with cell size, but how they adapt to local curvature remains unclear. Reaction-diffusion and actin-based transport are known to contribute to domain formation. However, the mechanism linking domain size to cell curvature is unknown. This gap motivated the current study. No prior work had resolved how domain width correlates with local curvature. Existing models do not account for curvature-specific scaling. The role of actin networks in sensing curvature has not been tested. This study aims to clarify how domain size adapts to cell geometry.

The study investigates how polarity domains adjust their size to local cell curvature. It focuses on Cdc42-GTP domains in fission yeast spores. The goal is to determine if domain width scales with curvature independently of cell volume or concentration. The research tests whether actin cables and vesicle transport influence domain size. The motivation is to uncover a general principle of morphogenesis. The study addresses an unmet need in understanding curvature adaptation. It aims to identify the role of actin networks in domain scaling. The findings could provide insights into how cells shape themselves.

The researchers tracked oscillating Cdc42-GTP domains in fission yeast spores. They measured domain width across different curvature ranges. The study used live-cell imaging to observe domain dynamics. Actin cable formation was assessed using formin activity markers. Secretory vesicle fusion was monitored to test transport effects. The experiments compared domain widths under varying curvature conditions. The team tested the role of actin networks in curvature sensing. They evaluated whether domain scaling depends on cell volume or concentration.

Domain width correlated with local cell-surface curvature across an 8-fold range. The scaling was independent of cell volume, surface area, or Cdc42-GTP concentration. Actin cables nucleated by formins were essential for domain scaling. Vesicle fusion along actin cables was required for domain extension. Reaction-diffusion mechanisms set a minimal domain size. Actin networks acted as curvature sensors at the micrometer scale. The findings suggest a generic morphogenetic principle. Domain size adapts to local geometry through actin-based transport.

The authors propose that actin networks sense curvature to adjust domain size. They suggest that reaction-diffusion sets a lower size limit. Secretory vesicle transport extends domains to match curvature. The study reveals a new role for actin in morphogenesis. The findings support a general principle of domain scaling. The adaptation occurs independently of cell volume or concentration. The work highlights the importance of local geometry in polarity formation. The results suggest actin-based transport as a curvature-sensing mechanism.