Protein Droplets Facilitate the Formation of Tight Junctions Between Cells

Centrala begrepp

Protein condensates formed through liquid-liquid phase separation can wet and remodel cell membranes, facilitating the formation of specialized tight junctions between cells.

Sammanfattning

The article discusses how cells use compartmentalization not only through membrane-bound organelles, but also through the formation of droplet-like macromolecular condensates. These condensates arise from weak and multivalent interactions between proteins or between proteins and nucleic acids, a process known as liquid-liquid phase separation.

When these condensates come into contact with cell membranes, a phenomenon called wetting is observed. Wetting refers to the way a liquid spreads over a 2D surface, similar to how a water droplet spreads over glass. This wetting process has been implicated in a broad range of biological processes.

The key finding reported in this article is that wetting of cell membranes by protein condensates underlies the formation of specialized connections called tight junctions between cells. Tight junctions are important for maintaining the integrity and permeability of epithelial and endothelial barriers in the body.

The article provides insights into how the physical properties of protein condensates and their interactions with membranes can drive the assembly of complex cellular structures like tight junctions, which are crucial for tissue and organ function.

Statistik

Cells compartmentalize biochemical reactions not only in membrane-bounded organelles, but also through the formation of droplet-like macromolecular condensates.
Condensates arise through a process called liquid–liquid phase separation, which is driven by weak and multivalent (occurring at multiple sites) interactions between proteins, or between proteins and nucleic acids.
When condensates come into contact with cell membranes, a phenomenon known as wetting is observed, which refers to the way in which a liquid spreads over a 2D surface.

Citat

"Wetting shapes and remodels membranes and has been implicated in a broad range of biological processes."
"The term refers to the way in which a liquid spreads over a 2D surface, much as a water droplet spreads over glass."

Viktiga insikter från

Protein droplets spread to seal tight junctions

by Alexander Lu... på www.nature.com 08-07-2024

https://www.nature.com/articles/d41586-024-02234-7

Djupare frågor

How might the physical properties of protein condensates, such as surface tension and viscosity, influence their ability to wet and remodel cell membranes?

The physical properties of protein condensates play a crucial role in their interaction with cell membranes. Surface tension, which is a measure of the force acting parallel to the surface of the liquid, determines how readily a condensate can spread on a membrane. Lower surface tension allows for better wetting, enabling the condensate to spread more easily over the membrane surface. Viscosity, on the other hand, affects the flow of the condensate on the membrane. Higher viscosity may hinder the spreading of the condensate, impacting its ability to remodel the membrane effectively. Therefore, a balance between surface tension and viscosity is essential for protein condensates to efficiently wet and remodel cell membranes.

What other cellular processes, beyond tight junction formation, might be regulated by the wetting of membranes by protein condensates?

The wetting of membranes by protein condensates can regulate various cellular processes beyond tight junction formation. For instance, the wetting of membranes by condensates could influence the formation of other cell-cell junctions such as adherens junctions or desmosomes, which are crucial for cell adhesion and tissue integrity. Additionally, membrane wetting by protein condensates might impact membrane trafficking processes, endocytosis, or even signaling cascades by modulating the spatial organization of membrane-bound proteins. Furthermore, the wetting properties of protein condensates could potentially affect membrane curvature and dynamics, thereby influencing processes like membrane fusion or fission.

Could the principles of protein condensate-mediated membrane wetting be leveraged to engineer synthetic cellular structures or interfaces with desired properties?

The principles of protein condensate-mediated membrane wetting offer exciting possibilities for engineering synthetic cellular structures or interfaces with specific properties. By understanding how protein condensates interact with cell membranes through wetting, researchers can potentially design artificial systems that mimic these behaviors. For example, synthetic membranes could be engineered to interact with designed protein condensates in a controlled manner, leading to the formation of artificial cell-cell junctions or membrane domains. These synthetic structures could be utilized in various applications, such as drug delivery systems, biosensors, or tissue engineering constructs, where precise control over membrane interactions is crucial. Leveraging the principles of protein condensate-mediated membrane wetting opens up new avenues for creating functional biomimetic materials with tailored properties.