Designing a membrane-bound liquid cortex for shaping synthetic cells

How do living cells change shape and move in response to stimuli? And how do intracellular membraneless condensates, formed by the process of liquid-liquid phase separation (LLPS), impact these vital processes? Inspired by living systems and using a bottom-up approach, this proposal will take the very first steps towards building a phase separation-based, membrane-bound biopolymer structure, capable of shaping and moving cell-mimicking vesicles.

Cellular morphogenesis is governed by an intracellular cytoskeleton, especially actin filaments and myosin motors. A particularly important structure is the cell cortex, a thin contractile sheet attached underneath the membrane. While research in recent years has hinted at the importance of LLPS in cytoskeletal organization at the membrane, further biochemical and biophysical insights are highly sought after. Inspired by this challenge, we will study the fundamental interplay between the active cytoskeleton, liquid-like condensates, and the deformable lipid membrane. We will utilize our expertise in on-chip microfluidic systems to achieve controlled and systematic experimentation. Our workhorse will be condensate-in-liposome structures formed by Octanol-assisted Liposome Assembly technique, a thoroughly tested versatile platform. Based on our encouraging latest results, we will first induce and characterize condensate-membrane interactions. By further encapsulating actomyosin components, we will study their organization and dynamics at condensate-coated membranes. Using confining microfabricated structures and by suspending the liposomes in extracellular matrices, we will test the ability of these cortex-containing liposomes to undergo shape changes, directed motion, and exhibit cell-like blebbing motility.

Our robust microfluidic approach and extensive experience in bottom-up biology significantly increases the success of this project. Moreover, excellent facilities and expertise in soft matter within the department will strongly facilitate this synthetic biology endeavor. This research will shed further light on the crucial role of LLPS in orchestrating cell shape and migration. It will also significantly contribute to the worldwide efforts of creating synthetic cells and may further act as a base towards building synthetic tissues and designing autonomous micro-robots, with far-reaching implications in biomedicine.