Stress fiber contraction induces cell body rotation in single keratocytes

Single epidermal keratocytes, which are responsible for wound repair in fish, migrate while maintaining their characteristic shape: a frontal crescent-shaped lamellipodium and a posterior rugby-ball-shaped cell body. These cells are widely used in cell migration studies, especially to examine the role of actin polymerization at the leading edge of the cell. In the posterior part of the cell, stress fibers, which are bundles of actomyosin, are aligned along the seam of the 'rugby ball.' The ball rotates with the stress fibers during migration. The linear contraction of stress fibers appears to drive the rotation of the cell body. This review describes a conversion mechanism from linear motion to rotation driven by stress fiber contraction and soft cell body deformation, which is not found in man-made machines. We also describe a unique research method that is able to demonstrate this machinery by creating robot models. Due to their high migration rate and ease of culturing, fish keratocytes appear to be one of the best materials for studying both single cell and collective cell migration. In this review, we will also give some recent research examples of collective migration using keratocytes.