Cited by 35Receptor Mechanisms and SignalingNeuroscience and Neuropharmacology ResearchProtein Kinase Regulation and GTPase Signaling

The ‘allosteric modulator’ SCH‐202676 disrupts G protein‐coupled receptor function via sulphydryl‐sensitive mechanisms

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Lewandowicz, Anna M, Vepsäläinen, Jouko, Laitinen, Jarmo T·2006·British Journal of Pharmacology

Abstract

1. Previous studies suggest that the thiadiazole compound SCH-202676 (N-(2,3-diphenyl-1,2,4-thiadiazol-5-(2H)-ylidene)methanamine) acts as an allosteric modulator of a variety of structurally distinct G protein-coupled receptors (GPCRs). It was postulated that SCH-202676 would directly bind a structural motif in the receptor molecule common to divergent members of the GPCR family. The molecular mechanisms of such a promiscuous action, however, remain obscure. 2. To clarify the mechanism of SCH-202676 action, we used the functional approach of [35S]GTPgammaS autoradiography with rat brain cryostat sections together with classical membrane [35S]GTPgammaS binding assays to evaluate how the thiadiazole affects G protein activity mediated by various receptors linked to the Gi-family of G proteins. 3. We found that in the absence of dithiotreitol (DTT), SCH-202676 (10(-7)-10(-5) M) elicits nonspecific effects in the [35S]GTPgammaS-based G protein activation assays, thereby severely compromising interpretations on the compounds ability to allosterically inhibit receptor-mediated G protein activity. Such a nonspecific behaviour was fully reversed upon addition of DTT (1 mM), revealing thiol-based mechanism of action. 4. In routine incubations containing DTT, SCH-202676 had no effect on receptor-driven G protein activity, as assessed for adenosine A1, alpha2-adrenergic, cannabinoid CB1, lysophosphatidic acid LPA1, muscarinic M2/M4, purinergic P2Y12 or sphingosine 1-phosphate receptors, suggesting that the thiadiazole does not act as an allosteric modulator of GPCR function. 5. 1H NMR analysis indicated that SCH-202676 underwent structural changes after incubation with the reducing agent DTT or with brain tissue. 6. We conclude that SCH-202676 modulates GPCRs via thiol modification rather than via true allosteric mechanisms.

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  • SCH-202676 is a global GPCR inhibitor that blocks agonist and antagonist binding to structurally diverse GPCRs coupling to Gαi/o, Gαs, and Gαq proteins.

    “SCH-202676, a global GPCR inhibitor that blocks both agonist and antagonist binding to structurally diverse GPCRs that couple to Gαi/o, Gαs and Gαq proteins (Fawzi et al., 2001; Lewandowicz et al., 2006).”

    From A Cardiovascular Disease-Linked Gut Microbial Metabolite Acts via Adrenergic Receptors (2020) · cites this paper as Lewandowicz et al., 2006

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Authors
Lewandowicz, A. M., Vepsäläinen, J., & Laitinen, J. T.
Affiliations
University of Eastern Finland (FI)
Corresponding author
Laitinen, Jarmo T
Venue
British Journal of Pharmacology
Publisher
Wiley
Published
2006-02
Volume
147
Issue
4
Pages
422-429
ISSN
  • 0007-1188 (ISSN-L)
  • 1476-5381
OpenAlex
W1964952712
Cited by
34
References
19
Citations by year
2026: 1 · 2025: 1 · 2024: 4 · 2023: 4 · 2022: 1 · 2020: 6 · 2018: 2 · 2017: 2 · 2016: 1 · 2015: 1 · 2014: 2 · 2012: 1
FWCI
0.54
Type
journal article
Language
en
Open access
Locations
  • British Journal of Pharmacology (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Receptor Mechanisms and Signaling
  • Life Sciences › Neuroscience › Cellular and Molecular Neuroscience › Neuroscience and Neuropharmacology Research
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Protein Kinase Regulation and GTPase Signaling
Keywords
thiadiazoles, G protein-coupled receptors, allosteric modulators, thiol modification, dithiothreitol, Gi protein, G protein activation, adenosine A1 receptor, alpha2-adrenoceptors, CB1 receptor, sphingosine-1-phosphate receptor
MeSH terms
Allosteric Regulation, Animals, Autoradiography, Brain Chemistry, Cell Membrane, Male, Radioligand Assay, Thiadiazoles, Thiazoles, Guanosine 5'-O-(3-Thiotriphosphate), Rats, Wistar, Nuclear Magnetic Resonance, Biomolecular, Receptors, G-Protein-Coupled, Rats

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