Contact Angle at the Leading Edge Controls Cell Protrusion Rate

• Published in: Current biology Vol. 24; no. 10; pp. 1126 - 1132
• Main Authors: Gabella, Chiara, Bertseva, Elena, Bottier, Céline, Piacentini, Niccolò, Bornert, Alicia, Jeney, Sylvia, Forró, László, Sbalzarini, Ivo F., Meister, Jean-Jacques, Verkhovsky, Alexander B.
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 19.05.2014
• Subjects: Actins - chemistry; Animals; Cell Membrane - physiology; Cell Movement; Cell Shape; Characidae - physiology; Epidermis - cytology; Epithelial Cells - cytology; Polymerization; Pressure
• ISSN: 0960-9822; 1879-0445
• DOI: 10.1016/j.cub.2014.03.050

Plasma membrane tension and the pressure generated by actin polymerization are two antagonistic forces believed to define the protrusion rate at the leading edge of migrating cells [1–5]. Quantitatively, resistance to actin protrusion is a product of membrane tension and mean local curvature (Laplace’s law); thus, it depends on the local geometry of the membrane interface. However, the role of the geometry of the leading edge in protrusion control has not been yet investigated. Here, we manipulate both the cell shape and substrate topography in the model system of persistently migrating fish epidermal keratocytes. We find that the protrusion rate does not correlate with membrane tension, but, instead, strongly correlates with cell roundness, and that the leading edge of the cell exhibits pinning on substrate ridges—a phenomenon characteristic of spreading of liquid drops. These results indicate that the leading edge could be considered a triple interface between the substrate, membrane, and extracellular medium and that the contact angle between the membrane and the substrate determines the load on actin polymerization and, therefore, the protrusion rate. Our findings thus illuminate a novel relationship between the 3D shape of the cell and its dynamics, which may have implications for cell migration in 3D environments. •Osmotic treatments affect cell velocity and shape, but not membrane tension•Protrusion velocity correlates with cell roundness, but not with membrane tension•The leading edge shows pinning at substrate ridges, a trait typical of liquid droplets•The results are explained in terms of force balance at a triple interface Gabella et al. investigated protrusion rate, membrane tension, and 3D shape of rapidly migrating cells. The results indicate that the leading edge can be considered a triple interface as defined for liquid droplets, and the contact angle between membrane and substrate controls actin assembly load and cell velocity.