Biology subjects

Lussier, F.

Publications and source records attributed to Lussier, F..

4 recordsLinked to original sources

bioRxiv2025

A neurotensin receptor type 1-derived pepducin acts as a biased allosteric modulator to regulate target receptor function

Pepducins are synthetic membrane-tethered lipopeptides designed to allosterically modulate G protein-coupled receptor (GPCR) signaling. Here, we characterize a series of pepducins targeting the neurotensin receptor type 1 (NTS1), revealing multifaceted modulation of this receptor class. Using BRET-based biosensors, we show that PP-001, a pepducin derived from NTS1s first intracellular loop, preferentially activates G protein over {beta}-arrestin signaling while inhibiting NT binding, NT-induced {beta}-arrestin recruitment, and NTS1 receptor internalization, thereby acting as biased allosteric agonist and negative allosteric modulator. PP-001 also promotes the formation of both homo- and heteromeric multi-receptor units. In vivo, PP-001 elicits potent, sustained hypotensive effects, reversible by the NTS1 antagonist SR48692. Finally, although the mechanism of pepducin-receptor interaction remains unclear, this study identifies a critical N-terminal RKK motif for PP-001s biological activity. Thermodenaturation assays with purified NTS1 and mutagenesis further provide evidence for the role of NTS1s H8 domain in direct pepducin-receptor interaction. This work highlights pepducins modulatory potential as pharmacological tools for GPCR-targeted drug development.

pharmacology and toxicology↗

bioRxiv2025

PiP-plex: A Particle-in-Particle System for Multiplexed Quantification of Secreted Proteins by Single Cells

Cell signaling is modulated by the secretion of various proteins, which can be used to infer a cells phenotype. However, these proteins cannot be readily detected in multiplex by commonly used methods at the single cell level. Here, we present PiP-plex, a particles-in-particle (PiPs) system comprising (i) fluorescence intensity barcoded microparticles (BMPs) co-entrapped with (ii) a single cell inside an alginate hydrogel particle for multiplex protein secretion analysis by confocal microscopy. We show that developed PiPs maintained >90 % cellular viability and allowed live cells retrieval. A seven-plex fluorescent barcoding and concomitant sandwich immunoassay in PiPs were implemented with limits of detection ranging from 0.8 pg mL-1 to 2 ng mL-1 depending on the protein. PiP-plex assays were benchmarked with bulk immunoassays and found to rival or outperform them. We applied PiP-plex to analyze protein secreted by THP-1 cells upon exposure to lipopolysaccharide and detected varying cell responses, with a significant increase in MIP-1, TNF- and IL-17A. Multivariate analysis revealed that the majority of stimulated cells secreted either MIP-1 or IL-17A, while other cytokines were typically co-secreted. Using PiP-plex, we analyzed [~]750 THP-1 cells, showcasing its potential for characterizing cells and cell-based therapeutics for cancer immunotherapies.

bioengineering↗

bioRxiv2023

Nanoporous PEGDA ink for High-Resolution Additive Manufacturing of Scaffolds for Organ-on-a-Chip

Polydimethylsiloxane (PDMS), commonly used in organ-on-a-chip (OoC) systems, faces limitations in replicating complex geometries, hindering its effectiveness in creating 3D OoC models. In contrast, poly(ethylene glycol)diacrylate (PEGDA-250), favored for its fabrication ease and resistance to small molecule absorption, is increasingly used for 3D printing microfluidic devices. However, applications in cell culture have been limited due to poor cell adhesion. Here, we introduce a nanoporous PEGDA ink (P-PEGDA) designed to enhance cell adhesion. P-PEGDA is formulated with a porogen, photopolymerized, followed by the porogen removal. Utilizing P-PEGDA, complex microstructures and membranes as thin as 27 {micro}m were 3D-printed. Porogen concentrations from 10-30% were tested yielding constructs with increasing porosity and oxygen permeability surpassing PDMS, without compromising printing resolution. Tests across four cell lines showed >80% cell viability, with a notable 77-fold increase in MDA-MB-231 cell coverage on the porous scaffolds. Finally, we introduce an OoC model comprising a gyroid scaffold with a central opening filled with a cancer spheroid. This setup, after a 14-day co-culture, demonstrated significant endothelial sprouting and integration within the spheroid. The P-PEGDA formulation is suitable for high-resolution 3D printing of constructs for 3D cell culture and OoC owing to its printability, gas permeability, biocompatibility, and cell adhesion.

bioengineering↗

bioRxiv2021

pH-Triggered Assembly of Endomembrane Multicompartments in Synthetic Cells

Bottom-up synthetic biology thrives to reconstruct basic cellular processes into a minimalist cellular replica to foster their investigation in greater details with a reduced number of variables. Among these cellular features, the endomembrane system is an important aspect of cells which is at the origin of many of their functions. Still, the reconstruction of these inner compartments within a lipid-based vesicle remains challenging and poorly controlled. Herein, we report the use of pH as external trigger to self-assemble compartmentalized giant unilamellar vesicles (GUVs) by either bulk, or droplet-based microfluidics. By co-encapsulating pH sensitive small unilamellar vesicles (SUVs), negatively charged SUVs and/or proteins, we show that acidification of the droplets efficiently produces GUVs while sequestrating the co-encapsulated material with flexibility and robustness. The method enables the simultaneous reconstruction of more than a single cellular phenotype from the bottom-up, corresponding to an important advancement in the current status quo of bottom-up synthetic biology.

synthetic biology↗