Coupling actin flow, adhesion, and morphology in a computational cell motility model.

Cell migration remains a complex biological process with multiple interacting components. Prior research has shown that actin polymerization and myosin-driven contraction contribute to cell movement. However, how these forces integrate with adhesion dynamics and membrane properties is not fully understood. No prior work had resolved how discrete adhesion sites influence cell morphology during migration. This paper's contribution lies in combining physical membrane properties with reaction-diffusion models of actin-myosin machinery. The study addresses a gap in understanding how adhesion states affect cell shape and movement. It builds on established knowledge of actin flow patterns in keratocytes but introduces a novel computational framework. The model integrates adhesion site states with actin filament dynamics. This approach allows researchers to explore how varying parameters influence cell behavior. The study's background highlights the need for a unified model of cell motility.

The study aims to develop a computational framework that integrates multiple physical and biochemical factors in cell motility. It focuses on how actin flow, adhesion states, and membrane forces interact to determine cell movement. The researchers sought to test this model using fish keratocytes, known for their consistent morphology during migration. They aimed to reproduce experimental findings on actin flow and stress patterns. The study's motivation stems from the lack of a unified model linking adhesion dynamics to cell shape and velocity. The researchers wanted to explore how changing myosin II activity and adhesion strength affects cell behavior. They also aimed to identify how adhesion site states influence actin flow patterns. The purpose is to provide a tool for understanding the physical mechanisms behind cell motility.

The researchers employed a phase-field method to simulate cell boundary movement with physical membrane properties. They combined this with a reaction-diffusion model for actin-myosin interactions. Discrete adhesion sites were modeled with two states: gripping and slipping. These adhesion sites were integrated with actin filament dynamics modeled as a viscous network. The model was tested using fish keratocytes, known for maintaining morphology during migration. The researchers varied myosin II activity and adhesion strength to explore cell motility phases. They compared model outputs to experimental results on actin flow and stress patterns. The model allowed them to simulate how different parameters affect cell velocity and shape.

The model successfully reproduced experimental findings on actin flow and stress patterns in keratocytes. It showed that cell velocity and morphology depend on actin polymerization, myosin contraction, adhesion forces, and membrane forces. Varying myosin II activity altered actin flow patterns and cell velocity. Increasing adhesion strength changed the cell's shape and movement dynamics. The model demonstrated that adhesion site states influence actin flow distribution. It revealed that the phase diagram of cell motility depends on myosin and adhesion parameters. The simulations matched observed stress patterns in migrating cells. The model suggests that cell morphology is determined by the integration of multiple forces.

The study concludes that cell motility depends on the integration of actin polymerization, myosin contraction, adhesion forces, and membrane properties. The model suggests that adhesion site states influence actin flow and cell morphology. It supports the idea that cell velocity is determined by the balance of these forces. The findings align with experimental observations of actin flow patterns in keratocytes. The model provides a framework for exploring how varying parameters affect cell behavior. It confirms that myosin II activity and adhesion strength determine motility phases. The study does not propose new drug targets or future research directions. It emphasizes the importance of integrating multiple physical and biochemical factors in cell motility models.