Goldfish keratocyte migration dynamics differ among horizontal, vertical, and clinorotation conditions

Abstract Gravity influences biological systems at many levels, yet its contribution to vertebrate cell migration remains poorly understood. Here, we examined how fish keratocytes alter their migratory behavior when the orientation of the gravity vector relative to the substrate is changed. At 30-s sampling intervals, keratocytes displayed distinct trajectory statistics on vertically and horizontally oriented substrates, including differences in migration speed and turning-angle dynamics. On vertical substrates, clinorotation and culture in medium with a specific gravity of 1.055 shifted these migration patterns toward those observed on horizontal substrates. Conversely, on horizontal substrates, weak externally applied medium flow induced changes resembling those observed under vertical culture. These responses developed rapidly, within 60 s, and were reversible in single cells during clinorotation experiments. Together, these findings demonstrate that keratocyte migration is sensitive to changes in the physical environment associated with substrate orientation, clinorotation, medium density, and weak flow. Although the results are consistent with a contribution of gravity-associated mechanical loading, they do not identify a specific force-transduction mechanism. The study therefore provides a phenomenological description of rapid, reversible modulation of keratocyte migration statistics by defined physical perturbations.