Martin Audet

Université de Sherbrooke | UdeS · Department of Pharmacology and Physiology

Prostaglandins are bioactive lipids involved in many physiological and pathophysiological conditions, such as pain, atherosclerosis, type II diabetes, and parturition. Prostaglandin E2 (PGE2) activates four G protein-coupled receptors (GPCRs), named the PGE2 types 1–4 receptors (EP1-4), to elicit the intracellular signaling responsible for their ph...

In the original Fig. 6b of Beautrait et al., Nat. Commun .2017 Apr 18;8:15054, one of the three representative image of the DMSO/AVP treatment group was inadvertently depicting the same cell, but from different zoomed areas. The herein new Fig. 6b now depicts three independent zoomed areas from different cells of DMSO/AVP and Barbadin/AVP treated g...

G protein–coupled receptors (GPCRs) are important pharmaceutical targets. Knowledge of their 3D structures is critical to understanding mechanisms of drug action. Low cellular expression, purification yield, and in vitro instability are substantial hurdles to the successful determination of GPCR structure. Intense effort is required to optimize a r...

In the version of this article originally published, the present address for Petr Popov was incorrectly listed as ‘Koltech Institute of Science & Technology, Moscow, Russia’. The correct present address is ‘Skolkovo Institute of Science and Technology, Moscow, Russia’. The error has been corrected in the HTML and PDF versions of the paper.

Misoprostol is a life-saving drug in many developing countries for women at risk of post-partum hemorrhaging owing to its affordability, stability, ease of administration and clinical efficacy. However, misoprostol lacks receptor and tissue selectivities, and thus its use is accompanied by a number of serious side effects. The development of pharma...

The first crystal structure of a G Protein‐Coupled Receptor (GPCR) was that of the bovine rhodopsin, solved in 2000, and is a light receptor within retina rode cells that enables vision by transducing a conformational signal from the light‐induced isomerization of retinal covalently bound to the receptor. More than seven years after this initial di...

Functional selectivity of G-protein-coupled receptors is believed to originate from ligand-specific conformations that activate only subsets of signaling effectors. In this study, to identify molecular motifs playing important roles in transducing ligand binding into distinct signaling responses, we combined in silico evolutionary lineage analysis...

Signaling across cellular membranes, the 826 human G protein-coupled receptors (GPCRs) govern a wide range of vital physiological processes, making GPCRs prominent drug targets. X-ray crystallography provided GPCR molecular architectures, which also revealed the need for additional structural dynamics data to support drug development. Here, nuclear...

In addition to G protein-coupled receptor (GPCR) desensitization and endocytosis, β-arrestin recruitment to ligand-stimulated GPCRs promotes non-canonical signalling cascades. Distinguishing the respective contributions of β-arrestin recruitment to the receptor and β-arrestin-promoted endocytosis in propagating receptor signalling has been limited...

Amino-acid sequences of human β2-adaptin

G-protein-coupled receptors serve as key signal transduction conduits, linking extracellular inputs with diverse cellular responses. These receptors eluded structural characterization for decades following their identification. A landmark structure of rhodopsin provided a basis for structure-function studies and homology modeling, but advances in r...

The discovery that drugs targeting a single G protein-coupled receptor (GPCR) can differentially modulate distinct subsets of the receptor signaling repertoire has created a challenge for drug discovery at these important therapeutic targets. Here, we demonstrate that a single label-free assay based on cellular impedance provides a real-time integr...

Statistical analysis of the variability of impedance responses. (A–E) Repeated impedance responses were obtained for ligands from each of the five groups of compounds. In each case, 3–7 independent measurements were made and mean impedance values (CI) were determined for each time-point. The mean impedance responses are shown in solid, colored line...

Visual assessment of clustering tendency of -adrenergic ligand impedance signatures. Gray levels represent the extent of dissimilarity between ligands as determined by area between the curves, ranging from black (smallest difference) to white (largest difference). Ligands are ordered based on similarities in the area between their curves. Ligands w...

ISO-induced Ca2+ response is β2AR-specific. 6HisHA-β2AR-HEK293S were pre-treated or not with the β2AR-selective antagonist ICI118,551 (100 nM) for 1 hour before stimulation with 1 µM ISO. Data represent means of three independent experiments (± SEM). (TIF)

Signaling and impedance responses in parental HEK293S and 6HisHA-β2AR-HEK293S cells. (A) Comparison of the impedance responses observed in parental HEK293S and 6HisHA-β2AR-HEK293S stable cell lines following treatment with ISO (1 µM). (B) Impedance responses upon ISO stimulation in the presence or absence of a 1 hour pre-treatment with the β2AR-sel...

Involvement of the MEK/ERK1/2 pathway in the ISO-promoted impedance response. Cells were transfected or not (Mock) with the MEK1-K97A-Flag dominant negative mutant 48 hours prior the impedance measurements and treated with ISO (1 µM). Data represent means of three independent experiments. (TIF)

Comparison of the direct inhibition of Gαs, Gβi and Gβγ vs inhibition of cAMP and ERK1/2 pathways on the impedance response. (A) Comparison of cholera toxin (CTX) and SQ22536 pre-treatments on the ISO-promoted impedance response (Figure 2A and 3A). (B) Comparison of pertussis toxin (PTX) and U0126 pre-treatments on the ISO-promoted impedance respon...

ISO-promoted impedance response is β2AR-specific. (A) Impedance response upon ISO stimulation following 1 hour pre-treatment with the β2AR-selective antagonist ICI118,551 (ICI) or the β1AR-selective antagonist CGP20712A (10 µM each). (B) Concentration-response curves of ISO-promoted maximum impedance response following pre-treatment with increasing...

Effect of thapsigargin on ISO-induced Ca2+ and impedance responses. ISO-induced Ca2+ response (A) and impedance response (B) upon pre-treatment or not with thapsigargin (TG, 5 µM) for 30 minutes. Data represent means (+/− SEM for A) from at least three independent experiments. (TIF)

Normalization and baseline-correction of impedance responses. (1) A measurement of cell index is made in the presence of growth medium prior to cell seeding to determine the background cell index in each well, which is subtracted from the cell index values generated by cell attachment. Cells are grown for 16–20 hours before ligand treatment. (2) Ce...

Monitoring the dynamics of protein-protein interactions in their natural environment remains a challenge. Resonance energy transfer approaches represent a promising avenue to directly probe these interactions in real time. The present study aims at establishing a proof of principle that bioluminescence resonance energy transfer (BRET) can be used t...

With more than 800 members, the G protein-coupled receptor family constitutes the largest group of membrane proteins involved in signal transduction. Until the end of last year, high-resolution three-dimensional structures were available for only one of them--the light receptor rhodopsin. Recently the structure of the beta(2)-adrenergic receptor ha...

Despite the fact that numerous studies suggest the existence of receptor multiprotein complexes, visualization and monitoring of the dynamics of such protein assemblies remain a challenge. In this study, we established appropriate conditions to consider spatiotemporally resolved images of such protein assemblies using bioluminescence resonance ener...

Activation of heterotrimeric G proteins by their cognate seven transmembrane domain receptors is believed to involve conformational changes propagated from the receptor to the G proteins. However, the nature of these changes remains unknown. We monitored the conformational rearrangements at the interfaces between receptors and G proteins and betwee...

In this study, the authors developed HEK293 cell lines that stably coexpressed optimal amounts of beta-arrestin2-Rluc and VENUS fusions of G protein-coupled receptors (GPCRs) belonging to both class A and class B receptors, which include receptors that interact transiently or stably with beta-arrestins. This allowed the use of a bioluminescence res...