Biology subjects

Blais, V.

Publications and source records attributed to Blais, V..

3 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

Optimization of the prostaglandin F2α receptor for structural biology

Prostaglandin F2[a] (PGF2[a]) is a bioactive lipid derived from arachidonic acid and is involved in many physiological and pathophysiological processes such as parturition, vascular tone regulation, glaucoma and inflammation. It acts by binding to the Prostaglandin F2[a] receptor (FP), a G Protein-Coupled Receptor (GPCR) that mediates signaling events by engaging intracellular heterotrimeric G protein effectors. The orthosteric binding site of lipid-binding receptors displays greater efficacy-dependent plasticity that hinders the design of ligands. Solving the structure of FP with ligands of different efficacies at an atomic level is important to fully understand its mechanism of activation and inhibition. Most purified FP-ligand complexes are unstable in vitro. The development of new X-ray crystallography and single particle cryo-electron (cryoEM) strategies to understand receptors signal transduction requires improved purification yield and in vitro stability of the receptor. Here, we present a protein engineering effort to optimize the FP protein sequence for use in structural biology. Strategies involve protein insertion sites in the third intracellular loop (ICL3), N-terminal and C-terminal deletions, and single-point mutations that favorably affect receptor purification yield and stability in vitro. The best FP construct displays a yield of 1.5 mg/L and a stability of 59{degrees}C that constitute a threefold improvement in purification yield and 9{degrees}C increase in stability over the wild-type receptor. These modifications in the receptor are suitable for pursuing alternative strategies for improving FP purification yield and for studying FP binding efficacy to its ligands through structural biology approaches.

pharmacology and toxicology↗

bioRxiv2021

Role of T cells in intrauterine administration of activated peripheral blood mononuclear cells in recurrent implantation failure.

Over the last few years, intrauterine administration of autologous peripheral blood mononuclear cells (PBMC) has been proposed as new immunotherapy for patients with unexplained recurrent implantation failure (RIF). In these patients, administration of activated PBMC before embryo transfer results in a 2-fold increase in live birth rates(Yang et al., 2020). In this study we evaluated the role of T cells to promotes human endometrial receptivity. On the day of ovulation, PBMC were isolated from and activated with T cells mitogen, the phytohemagglutinin (PHA) and hCG for 48-h in a conditioned culture medium. Distributions of CD4+ T cells were characterized in 157 patients by flow cytometry before and after PHA/hCG activation. Cytokine production was analyzed by cytometric beads array. We observed in RIF patients a significant decrease in Th2 and natural Treg cells before activation with PHA/hCG and an increase of Th17 cells after activation compared to intrauterine sperm insemination (IUI) and in vitro fertilization (IVF) groups. Furthermore, the hCG/PHA treatment increases anti-inflammatory T cells (Th2 and Treg cells) compared to non-treated T cells. Principal component analysis (PCA) performed on CD4 T cell subtypes revealed a different cellular profile in the RIF compared to the IUI and IVF groups. This inflammatory state change could explain how endometrium immunomodulation by hCG-activated PBMC helps patients with unexplained RIF to reach implantation.

immunology↗