Abstract: Living cells undergo continuous shape changes facilitated by contractile forces. The actin cytoskeleton plays a crucial role in generating the necessary contractile forces for various cellular processes. To investigate the effects of actomyosin contractility on cellular-scale changes, numerous in vitro experiments have been conducted using synthetic cell-like systems. These systems typically comprise actin, cross-linking proteins, and myosin motors enclosed within lipid vesicles or water droplets. These experiments aim to understand how forces derived from actomyosin contractility contribute to alterations in cell structure and function. Despite the insights these artificial systems have offered, inherent experimental constraints have kept us from completely comprehending the underlying mechanisms governing the changes in cell structure. In order to surpass the constraints and systematically study alterations in cell morphology, we created an agent-based model. This model represents a simple cell-like structure that consists of a discrete actomyosin cortex, osmotic pressure, and cell membrane. The purpose of this model is to better understand how these components interact and contribute to changes in cell shape. The actomyosin cortex consists of actin filaments, cross-linking proteins, and molecular motors. It is assumed that a fraction of the cross-linking proteins can be bound to the membrane. Motions of all elements are governed by the Langevin equation based on Brownian dynamics. Using the model, we explored a wide parametric space consisting of network connectivity, motor density, and cortex-membrane coupling. We found that forces generated from the actomyosin network induce distinct cell shape changes depending on conditions. If the cortex is tightly coupled to the membrane, contractile forces lead to uneven membrane surfaces. If the cortex is weakly coupled to the membrane, the cortex is separated from the membrane and contracts by itself. Interestingly, blebs are formed when the cortex induces enough contractility, and the cortex-membrane coupling is at an intermediate level. Results from our study shed light on fundamental mechanisms of cell shape changes driven by a competition between osmotic pressure and actomyosin contractility.

*Join Zoom Meeting

https://purdue-edu.zoom.us/j/98811885943?pwd=Nll1MlE3TTYyOHZJL3hIYlpGSXhUUT09

Meeting ID: 988 1188 5943    Passcode: biomedical

Evaluation link for Fahmida Sultana Laboni: https://purdue.ca1.qualtrics.com/jfe/form/SV_d5KOVoQQX0rz1sy