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Wardman J.H.,Yeshiva University | Zhang X.,Yeshiva University | Gagnon S.,Institute Of Pharmacologie Of Sherbrooke | Castro L.M.,University of Sao Paulo | And 4 more authors.
Journal of Neurochemistry | Year: 2010

Neuropeptides are produced from larger precursors by limited proteolysis, first by endopeptidases and then by carboxypeptidases. Major endopeptidases required for these cleavages include prohormone convertase (PC) 1/3 and PC2. In this study, quantitative peptidomics analysis was used to characterize the specific role PC1/3 plays in this process. Peptides isolated from hypothalamus, amygdala, and striatum of PC1/3 null mice were compared with those from heterozygous and wild-type mice. Extracts were labeled with stable isotopic tags and fractionated by HPLC, after which relative peptide levels were determined using tandem mass spectrometry. In total, 92 peptides were found, of which 35 were known neuropeptides or related peptides derived from 15 distinct secretory pathway proteins: 7B2, chromogranin A and B, cocaine- and amphetamine-regulated transcript, procholecystokinin, proenkephalin, promelanin concentrating hormone, proneurotensin, propituitary adenylate cyclase-activating peptide, proSAAS, prosomatosatin, provasoactive intestinal peptide, provasopressin, secretogranin III, and VGF. Among the peptides derived from these proteins, ∼1/3 were decreased in the PC1/3 null mice relative to wild-type mice, ∼1/3 showed no change, and ∼1/3 increased in PC1/3 null. Cleavage sites were analyzed in peptides that showed no change or that decreased in PC1/3 mice, and these results were compared with peptides that showed no change or decreased in previous peptidomic studies with PC2 null mice. Analysis of these sites showed that while PC1/3 and PC2 have overlapping substrate preferences, there are particular cleavage site residues that distinguish peptides preferred by each PC. © 2010 International Society for Neurochemistry.


Bourassa P.,University of Montreal | Bourassa P.,Universite de Sherbrooke | Tudashki H.B.,University of Montreal | Pineyro G.,University of Montreal | And 7 more authors.
Molecular Pharmacology | Year: 2014

In this study, we used a combination of traditional signaling investigation approaches, bioluminescence resonance energy transfer (BRET) biosensors, and the label-free approach surface plasmon resonance (SPR) spectroscopy to monitor the signaling cascades of the μ-opioid receptor (MOP). In human embryonic kidney cells stably expressing a Flag-tagged version of human MOP, we compared the signals triggered by the noninternalizing and internalizing MOP agonists morphine and DAMGO (Tyr-D-Ala-Gly-N-methyl-Phe-Gly-ol), respectively. We studied three major and well described components of MOP signaling: receptor internalization, G protein coupling, and activation of extracellular signal-regulated kinase ERK1/ERK2. Our results show that morphine and DAMGO display different profiles of receptor internalization and a similar ability to trigger the phosphorylation of ERK1/ERK2. Our SPR analyses revealed that morphine and DAMGO evoke similar SPR signatures and that Gαi, cAMP-dependent pathways, and ERK1/ERK2 have key roles in morphine- and DAMGO-mediated signaling. Most interestingly, we found that the so-called MOP neutral antagonists CTOP (D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2), naloxone, and naltrexone behave like partial agonists. Even more intriguing, BRET experiments indicate that CTAP (D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH 2) induces similar conformational changes as naltrexone at the Gαi-βγ interface, whereas it appears as an inverse agonist based on its SPR response thus indicating distinct signaling mechanisms for the two ligands. Taken together, our results support the usefulness of label-free methods such as SPR to study whole-cell responses and signaling cascades triggered by G protein-coupled receptors and complement the conventional approaches by revealing cellular responses that would have been otherwise undetectable. Copyright © 2014 by The American Society for Pharmacology and Experimental Therapeutics.


Iorio-Morin C.,Universite de Sherbrooke | Iorio-Morin C.,Institute Of Pharmacologie Of Sherbrooke | Germain P.,Universite de Sherbrooke | Germain P.,Institute Of Pharmacologie Of Sherbrooke | And 2 more authors.
Electrophoresis | Year: 2013

Western blotting is a proven technique essential to a significant proportion of molecular biology projects. However, as results accumulate over the years, managing data can become daunting. Recognizing that the needs of a scientist working with Western blotting results are conceptually the same as those of a professional photographer managing a summer's worth of wedding photos, we report here a new workflow for managing Western blotting results using professional photo management software. The workflow involves (i) scanning all film-based results; (ii) importing the scans into the software; (iii) processing the scans; (iv) tagging the files with metadata, and (v) creating appropriate "smart-albums." Advantages of this system include space savings (both on our hard drives and on our desks), safer archival, quicker access, and easier sharing of the results. In addition, metadata-based workflows improve cross-experiment discovery and enable questions like "show me all blots labelled with antibody X" or "show me all experiments featuring protein Y". As project size and breadth increase, workflows delegating results management to the computer will become more and more important so that scientists can keep focussing on science. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Mathurin K.,Universite de Sherbrooke | Mathurin K.,Institute Of Pharmacologie Of Sherbrooke | Gallant M.A.,Universite de Sherbrooke | Gallant M.A.,Institute Of Pharmacologie Of Sherbrooke | And 14 more authors.
Journal of Biological Chemistry | Year: 2011

L-type prostaglandin synthase (L-PGDS) produces PGD2, a lipid mediator involved in neuromodulation and inflammation. Here, we show that L-PGDS and arrestin-3 (Arr3) interact directly and can be co-immunoprecipitated endogenously from MG-63 osteoblasts. Perinuclear L-PGDS/Arr3 co-localization is observed in PGD2-producing MG-63 cells and is induced by the addition of the L-PGDS substrate or co-expression of COX-2 in HEK293 cells. Inhibition of L-PGDS activity in MG-63 cells triggers redistribution of Arr3 and L-PGDS to the cytoplasm. Perinuclear localization of L-PGDS is detected in wild-type mouse embryonic fibroblasts (MEFs) but is more diffused in MEFs-arr-2 -/--arr-3-/-. Arrestin-3 promotes PGD2 production by L-PGDS in vitro. IL-1β-induced PGD2 production is significantly lower in MEFs-arr-2-/--arr-3-/- than in wild-type MEFs but can be rescued by expressing Arr2 or Arr3. A peptide corresponding to amino acids 86-100 of arrestin-3 derived from its L-PGDS binding domain stimulates L-PGDS-mediated PGD2 production in vitro and in MG-63 cells. We report the first characterization of an interactor/ modulator of a PGD2 synthase and the identification of a new function for arrestin, which may open new opportunities for improving therapies for the treatment of inflammatory diseases. © 2011 by The American Society for Biochemistry and Molecular Biology, Inc.


Murza A.,Universite de Sherbrooke | Murza A.,Institute Of Pharmacologie Of Sherbrooke | Sainsily X.,Universite de Sherbrooke | Sainsily X.,Institute Of Pharmacologie Of Sherbrooke | And 21 more authors.
Journal of Medicinal Chemistry | Year: 2016

ELABELA (ELA) was recently discovered as a novel endogenous ligand of the apelin receptor (APJ), a G protein-coupled receptor. ELA signaling was demonstrated to be crucial for normal heart and vasculature development during embryogenesis. We delineate here ELA's structure-activity relationships and report the identification of analogue 3 (ELA(19-32)), a fragment of ELA that binds to APJ, activates the Gαi1 and β-arrestin-2 signaling pathways, and induces receptor internalization similarly to its parent endogenous peptide. An alanine scan performed on 3 revealed that the C-terminal residues are critical for binding to APJ and signaling. Finally, using isolated-perfused hearts and in vivo hemodynamic and echocardiographic measurements, we demonstrate that ELA and 3 both reduce arterial pressure and exert positive inotropic effects on the heart. Altogether, these results present ELA and 3 as potential therapeutic options in managing cardiovascular diseases. © 2016 American Chemical Society.

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