Design and characterization of superpotent bivalent ligands targeting oxytocin receptor dimers via a channel-like structure

Marta Busnelli, Gunnar Kleinau, Markus Muttenthaler, Stoytcho Stoev, Maurice Manning, Lucka Bibic, Lesley A. Howell, Peter J. McCormick, Simona Di Lascio, Daniela Braida, Mariaelvina Sala, G. Enrico Rovati, Tommaso Bellini, Bice Chini

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Dimeric/oligomeric states of G-protein coupled receptors have been difficult to target. We report here bivalent ligands consisting of two identical oxytocin-mimetics that induce a three order magnitude boost in G-protein signaling of oxytocin receptors (OTRs) in vitro and a 100- and 40-fold gain in potency in vivo in the social behavior of mice and zebrafish. Through receptor mutagenesis and interference experiments with synthetic peptides mimicking transmembrane helices (TMH), we show that such superpotent behavior follows from the binding of the bivalent ligands to dimeric receptors based on a TMH1-TMH2 interface. Moreover, in this arrangement, only the analogues with a well-defined spacer length (∼25 Å) precisely fit inside a channel-like passage between the two protomers of the dimer. The newly discovered oxytocin bivalent ligands represent a powerful tool for targeting dimeric OTR in neurodevelopmental and psychiatric disorders and, in general, provide a framework to untangle specific arrangements of G-protein coupled receptor dimers.
Original languageEnglish
Pages (from-to)7152–7166
Number of pages15
JournalJournal of Medicinal Chemistry
Issue number15
Early online date15 Jul 2016
Publication statusPublished - 11 Aug 2016

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