Peptide YY3-36 (PYY3-36) is an endogenous ligand of the neuropeptide Y2 receptor (Y2R), through which it acts to reduce food intake. Accordingly, PYY3-36 analogues are interesting as potential anti-obesity pharmaceuticals. However, native PYY3-36 is rapidly cleared from circulation, and half-life extension is thus a prerequisite for PYY3-36 based pharmaceuticals. This is typically achieved by covalent attachment of PYY3-36 to macromolecules (e.g. PEG) or through lipidation which promotes non-covalent interactions to albumin. Many peptide drugs, like PYY3-36, require binding to a specific G protein coupled receptor (GPCR) to exert their effect. GPCRs are desensitized and internalized following intracellular binding of β-arrestins, which bind to the ligand-activated conformation of the receptor.
Beck-Sickinger and co-workers recently reported how PEGylation and lipidation differentially directs arrestin 3 (Arr3) recruitment and receptor internalization of obinepitide, another peptide of the neuropeptide Y receptor system. Hence, the half-life extender selected for PYY3-36 therapeutics may alter its efficacy. Accordingly, we aimed to investigate how three commonly applied half-life extenders, PEGylation (PEG20), hexadecanoic acid (C16), and octadecanedioic acid (C18-acid), directs Y2R-mediated internalization of PYY3-36. Here we report how PEGylation leads to a G protein bias and reduced Y2R internalization. We further report how lipidation with both C16 and C18-acid did not bias Y2R signalling, whereas only C16 increased Y2R internalization. Finally, we demonstrate how binding kinetics underlay some of these differences.
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2 Mäde V, et al. Angew. Chemie - Int. Ed. 2014; 53: 10067–10071