Vesicle Induced Receptor Sequestration: Mechanisms behind Extracellular Vesicle‐Based Protein Signaling

Abstract

Extracellular vesicles (EVs) are fundamental for proper physiological functioning of multicellular organisms. By shuttling nucleic acids and proteins between cells, EVs regulate a plethora of cellular processes, especially those involved in immune signalling. However, the mechanistic understanding concerning the biophysical principles underlying EV-based communication is still incomplete. Towards holistic understanding, particular mechanisms explaining why and when cells apply EV-based communication and how protein-based signalling is promoted by EV surfaces are sought. Here, the authors study vesicle-induced receptor sequestration (VIRS) as a universal mechanism augmenting the signalling potency of proteins presented on EV-membranes. By bottom-up reconstitution of synthetic EVs, the authors show that immobilization of the receptor ligands FasL and RANK on EV-like vesicles, increases their signalling potential by more than 100-fold compared to their soluble forms. Moreover, the authors perform diffusion simulations within immunological synapses to compare receptor activation between soluble and EV-presented proteins. By this the authors propose vesicle-triggered local clustering of membrane receptors as the principle structural mechanism underlying EV-based protein presentation. The authors conclude that EVs act as extracellular templates promoting the local aggregation of membrane receptors at the EV contact site, thereby fostering inter-protein interactions. The results uncover a potentially universal mechanism explaining the unique structural profit of EV-based intercellular signalling.

Bottom-up assembly of viral replication cycles

“…Bottom-up synthetic biology has opened up new avenues for the construction of artificial systems that recreate the structure and function of living cells. New fundamental knowledge about the mechanisms underlaying life, such as the physical principles of cell division 1 , cellular motility 2 , cell communication 3 and morphogenesis 4 has been achieved by the application of in vitro reconstitution approaches. In the present context, we define bottom-up synthetic biology as a field that strives to construct minimal life-like materials by bottom-up reconstitution of cellular phenomena in vitro 5 .…”

Extracellular Vesicle Mimetics: Preparation from Top‐Down Approaches and Biological Functions

“…[25] Designing vesicle-induced chemoreceptors on the EVs mimetic membranes significantly enhances signaling efficacy compared to soluble forms of signaling. [26] In addition to disease treatment, these engineered EVs mimetic can also be used for the characterization of physicochemical properties. Lozano-Andrés et al have added biotinylated recombinant tetraspanins to synthetic nanovesicles, [27] which can be used in assay techniques such as dot blotting, protein blotting, nanoparticle tracking analysis (NTA), flow cytometry, and transmission electron microscopy (TEM).…”

“…[ 25 ] Designing vesicle‐induced chemoreceptors on the EVs mimetic membranes significantly enhances signaling efficacy compared to soluble forms of signaling. [ 26 ] In addition to disease treatment, these engineered EVs mimetic can also be used for the characterization of physicochemical properties. Lozano‐Andrés et al.…”

Enhancing functionalized liposome avidity to cells via lipid phase separation

“…As a result, the enhanced binding of NPs to cells can lead to more efficient activation of cellular receptors through subsequent cluster-dependent signaling. [21][22][23][24] One way to control ligand spatial presentation on nanoparticles is through lipid phase separation. By mixing saturated and unsaturated phospholipids with cholesterol, bilayer vesicles can undergo phase separation between the saturated liquid ordered (l o ) and unsaturated liquid disordered (l d ) phases, in a similar manner as cellular lipid rafts.…”