Half-Life Extending Modifications of Peptide YY_3-36 Direct Receptor-Mediated Internalization

Peptide YY_3-36 (PYY_3-36) is an endogenous ligand of the neuropeptide Y₂ receptor (Y₂R), on which it acts to reduce food intake. Chemically modified PYY_3-36 analogues with extended half-lives are potential therapeutics for the treatment of obesity. Here we show that the common half-life extending strategies PEGylation and lipidation not only control PYY_3-36's pharmacokinetics but also affect central aspects of its pharmacodynamics. PEGylation of PYY_3-36 inhibited endocytosis by increasing receptor dissociation rates (k_off), which reduced arrestin-3 (Arr3) activity. This is the first link between Arr3 recruitment and Y₂R residence time. C16-lipidation of PYY_3-36 had a negligible impact on Y₂R signaling, binding, and endocytosis. In contrast, C18acid-lipidation minimized endocytosis, which indicated a decreased internalization through non-arrestin-related mechanisms. We propose a temporal model that connects the properties and position of the half-life extender with receptor G_i versus Arr3 signaling bias. We believe that this will be important for future design of peptide therapeutics.