Cell cycle–dependent active stress drives epithelia remodeling

• Authors: John Devany, Institute for Biophysical Dynamics; Daniel Sussman, Emory University; Takaki Yamamoto, RIKEN Center for Biosystems Dynamics Research; Lisa Manning, Syracuse University; Margaret L Gardel, Institute for Biophysical Dynamics
• Journal Title: Proceedings of the National Academy of Sciences of the United States of America
• Volume: Volume 118, Number 10
• Publisher: PNAS | 2021-03-09
• Type of Work: Article | Final Publisher PDF
• Publisher DOI: http://doi.org/10.1073/pnas.1917853118
• Subjects: Health Sciences, Medicine and Surgery
• Keywords: cell cycle; cell mechanics; epithelial tissue; vertex model; Animals; Cell Cycle; Cell Shape; Dogs; Epithelial Cells; Extracellular Matrix; Madin Darby Canine Kidney Cells; Stress, Physiological

Abstract

Epithelia have distinct cellular architectures which are established in development, reestablished after wounding, and maintained during tissue homeostasis despite cell turnover and mechanical perturbations. In turn, cell shape also controls tissue function as a regulator of cell differentiation, proliferation, and motility. Here, we investigate cell shape changes in a model epithelial monolayer. After the onset of confluence, cells continue to proliferate and change shape over time, eventually leading to a final architecture characterized by arrested motion and more regular cell shapes. Such monolayer remodeling is robust, with qualitatively similar evolution in cell shape and dynamics observed across disparate perturbations. Here, we quantify differences in monolayer remodeling guided by the active vertex model to identify underlying order parameters controlling epithelial architecture. When monolayers are formed atop an extracellular matrix with varied stiffness, we find the cell density at which motion arrests varies significantly, but the cell shape remains constant, consistent with the onset of tissue rigidity. In contrast, pharmacological perturbations can significantly alter the cell shape at which tissue dynamics are arrested, consistent with varied amounts of active stress within the tissue. Across all experimental conditions, the final cell shape is well correlated to the cell proliferation rate, and cell cycle inhibition immediately arrests cell motility. Finally, we demonstrate cell cycle variation in junctional tension as a source of active stress within the monolayer. Thus, the architecture and mechanics of epithelial tissue can arise from an interplay between cell mechanics and stresses arising from cell cycle dynamics.