In JoVE (2)
- En kinetisk fluorescens-baserad certifikatutfärdare2 + mobilisering analysen identifiera G-proteinkopplade receptoragonister och antagonister Allosteriska modulatorer
- En flöde flödescytometri-baserad analys identifiera föreningar som stör bindningen av Fluorescently-märkta CXC Chemokine Ligand 12 till CXC Chemokine Receptor 4
Articles by Tom Van Loy in JoVE
En kinetisk fluorescens-baserad certifikatutfärdare2 + mobilisering analysen identifiera G-proteinkopplade receptoragonister och antagonister Allosteriska modulatorer Sandra Claes1, Thomas D'huys1, Anneleen Van Hout1, Dominique Schols1, Tom Van Loy1 1Laboratory of Virology and Chemotherapy, Department of Microbiology and Immunology, Rega Institute for Medical Research, KU Leuven Beskrivna cellulära analysen är utformad för identifiering av CXC chemokine receptor 4 (CXCR4)-interagerande agenter som hämmar eller stimulera, antingen konkurrenskraftigt eller allosterically, intracellulära Ca2 + frisättning initierats av CXCR4 aktivering.
En flöde flödescytometri-baserad analys identifiera föreningar som stör bindningen av Fluorescently-märkta CXC Chemokine Ligand 12 till CXC Chemokine Receptor 4 Geert Schoofs1, Anneleen Van Hout1, Thomas D'huys1, Dominique Schols1, Tom Van Loy1 1Laboratory of Virology and Chemotherapy, Department of Microbiology and Immunology, Rega Institute for Medical Research, KU Leuven Ett flöde flödescytometri-baserade cellulära bindande analys beskrivs som används främst som en screeningmetod för att identifiera substanser som hämmar bindningen av en fluorescently märkt CXC chemokine ligand 12 (CXCL12) till CXC chemokine receptorn 4 (CXCR4).
Other articles by Tom Van Loy on PubMed
Substitution of Conserved Glycine Residue by Alanine in Natural and Synthetic Neuropeptide Ligands Causes Partial Agonism at the Stomoxytachykinin Receptor Journal of Neurochemistry. | Pubmed ID: 15228603 A few naturally occurring insect tachykinin-related peptides, such as stomoxytachykinin (Stc-TK), contain an Ala-residue instead of the highly conserved Gly-residue that is present in most other members of this peptide family. Stc-TK is a potent, partial agonist of the stable fly (Stomoxys calcitrans) tachykinin receptor, STKR. By means of synthetic analogues, the Gly/Ala exchange, representing the addition of a single methyl group in the active core region of these peptides, was shown to be fully responsible for the generation of this partial agonism, which was also accompanied by an increase in agonistic potency. Surprisingly, this Ala-dependent reduction in maximal response levels was only observed for the agonist-induced cellular calcium rise. Stomoxytachykinin, Stc-TK, did not display partial agonism for the STKR-mediated cyclic AMP response. A possible explanation for this differential partial agonism is that the Gly-containing and Ala-replaced peptides recognize and stabilize active receptor conformations that differ in their functional coupling efficacies towards these response pathways. Drosotachykinins, Drm-TK, tachykinin-like peptides encoded in the fruit fly genome, were shown to be STKR-agonists. Interestingly, one of these peptides, which contains an Ala-residue instead of the conserved Gly-residue, also proved to be a potent, partial agonist for STKR.
Silencing D. Melanogaster Lgr1 Impairs Transition from Larval to Pupal Stage General and Comparative Endocrinology. | Pubmed ID: 25157788 G protein-coupled receptors (GPCRs) play key roles in a wide diversity of physiological processes and signalling pathways. The leucine-rich repeats containing GPCRs (LGRs) are a subfamily that is well-conserved throughout most metazoan phyla and have important regulatory roles in vertebrates. Here, we report on the critical role of Drosophila melanogaster LGR1, the fruit fly homologue of the vertebrate glycoprotein hormone receptors, in development as a factor involved in the regulation of pupariation. Transcript profiling revealed that lgr1 transcripts are most abundant in third instar larvae and adult flies. The tissues displaying the highest transcript levels were the hindgut, the rectum and the salivary glands. Knockdown using RNA interference (RNAi) demonstrated that white pupa formation was severely suppressed in D. melanogaster lgr1 RNAi larvae. Associated with this developmental defect was a reduced ecdysteroid titer, which is in line with significantly reduced transcript levels detected for the Halloween genes shadow (sad) and spookier (spok) in the third instar lgr1 RNAi larvae compared to the control condition.
Comparison of Cell-based Assays for the Identification and Evaluation of Competitive CXCR4 Inhibitors PloS One. | Pubmed ID: 28410420 The chemokine receptor CXCR4 is activated by its unique chemokine ligand CXCL12 and regulates many physiological and developmental processes such as hematopoietic cell trafficking. CXCR4 is also one of the main co-receptors for human immunodeficiency virus (HIV) entry. Dysfunction of the CXCL12/CXCR4 axis contributes to several human pathologies, including cancer and inflammatory diseases. Consequently, inhibition of CXCR4 activation is recognized as an attractive target for therapeutic intervention. In this regard, numerous agents modifying CXCR4 activity have been evaluated in in vitro experimental studies and pre-clinical models. Here, we evaluated a CXCL12 competition binding assay for its potential as a valuable initial screen for functional and competitive CXCR4 inhibitors. In total, 11 structurally diverse compounds were included in a side-by-side comparison of in vitro CXCR4 cell-based assays, such as CXCL12 competition binding, CXCL12-induced calcium signaling, CXCR4 internalization, CXCL12-guided cell migration and CXCR4-specific HIV-1 replication experiments. Our data indicated that agents that inhibit CXCL12 binding, i.e. the anti-CXCR4 peptide analogs T22, T140 and TC14012 and the small molecule antagonists AMD3100, AMD3465, AMD11070 and IT1t showed inhibitory activity with consistent relative potencies in all further applied CXCR4-related assays. Accordingly, agents exerting no or very weak receptor binding (i.e., CTCE-9908, WZ811, Me6TREN and gambogic acid) showed no or very poor anti-CXCR4 inhibitory activity. Thus, CXCL12 competition binding studies were proven to be highly valuable as an initial screening assay and indicative for the pharmacological and functional profile of competitive CXCR4 antagonists, which will help the design of new potent CXCR4 inhibitors.
Signaling Properties of the Human Chemokine Receptors CXCR4 and CXCR7 by Cellular Electric Impedance Measurements PloS One. | Pubmed ID: 28945785 The chemokine receptor 4 (CXCR4) and 7 (CXCR7) are G-protein-coupled receptors involved in various diseases including human cancer. As such, they have become important targets for therapeutic intervention. Cell-based receptor assays, able to detect agents that modulate receptor activity, are of key importance for drug discovery. We evaluated the potential of cellular electric impedance for this purpose. Dose-dependent and specific stimulation of CXCR4 was detected upon addition of its unique chemokine ligand CXCL12. The response magnitude correlated with the CXCR4 expression level. Gαi coupling and signaling contributed extensively to the impedance response, whereas Gαq- and Gβγ-related events had only minor effects on the impedance profile. CXCR7 signaling could not be detected using impedance measurements. However, increasing levels of CXCR7 expression significantly reduced the CXCR4-mediated impedance readout, suggesting a regulatory role for CXCR7 on CXCR4-mediated signaling. Taken together, cellular electric impedance spectroscopy can represent a valuable alternative pharmacological cell-based assay for the identification of molecules targeting CXCR4, but not for CXCR7 in the absence of CXCR4.