PYY preference is a common characteristic of neuropeptide Y receptors expressed in human, rat, and mouse gastrointestinal epithelia

Abstract

This investigation describes the relative potencies of four peptide agonists, namely, peptide YY (PYY), [Leu3l,Pro34]PYY (Pro34pYY), neuropeptide Y (NPY), and [Leu31,Pro34]NPY (Pro34NPY), as antisecretory agents in human, rat, and mouse gastrointestinal preparations. The inhibition of agonist responses by the Y1-receptor antagonist BIBP 3226 was also tested in each preparation. An unexpectedly pronounced preference for PYY and Pro34PYY was observed in functional studies of two human epithelial lines stably transfected with the rat Y1 receptor (Y1-7 and C1Y1-6). NPY and Pro34NPY were at least an order of magnitude less effective than PYY in these functional studies but were only marginally less potent in displacement binding studies using membrane preparations of the same clonal lines. The orders of agonist potency obtained in Y1-7 and C1Y1-6 epithelia were compared with those obtained from a single human colonic adenocarcinoma cell line (Colony-6, which constitutively expresses Y1 receptors) and also from mucosal preparations of rat and mouse descending colon. Similar peptide orders of potency were obtained in rat and mouse colonic mucosae and Colony-6 epithelia, all of which exhibited PYY preference (although less pronounced than with Y1-7 and C1Y1-6 epithelia) and significant sensitivity to the Y1 receptor antagonist, BIBP 3226. We have compared the pharmacology of these five mammalian epithelial preparations and provide cautionary evidence against the reliance upon agonist concentration-response relationships alone, in the characterization of NPY receptor types.

Contribution of a tyrosine-based motif to cellular trafficking of wild-type and truncated NPY Y1 receptors

“…1B) might reflect internalized receptors due to tonic internalization in the absence of agonist, as recently suggested [13]. Cells expressing Y 1 Δ32 receptors were incubated at 4°C, a condition which fully inhibits Y 1 receptor internalization due to the temperature dependence of the internalization process [21].…”

“…Arrestins then serve as scaffold proteins by binding directly to the AP-2 complex and the clathrin necessary for coat formation. Recent studies have determined which serine and threonine are necessary for β-arrestins binding to the Y 1 C-terminus receptor in response to agonist activation [13,14,32]. This stretch of serine/threonine is located distally compared to the YETI motif (see Table 1) and is thus absent in the Y 1 Δ32 and Y 1 Δ42 receptors.…”

“…The C-terminus of GPCRs is also a site for G protein-coupled receptor kinase (GRK)-mediated phosphorylation and arrestin interactions [12]. Recently, truncated rat Y 1 receptors have been reported to undergo agonist-independent constitutive internalization based on confocal microscopy (co-localization with transferrin-positive early and recycling endosomes) [13]. However, the molecular determinants of this internalization were not demonstrated [13].…”

“…Recently, truncated rat Y 1 receptors have been reported to undergo agonist-independent constitutive internalization based on confocal microscopy (co-localization with transferrin-positive early and recycling endosomes) [13]. However, the molecular determinants of this internalization were not demonstrated [13]. In an attempt to identify the residues triggering agonistinduced internalization of human Y 1 receptors we recently analyzed several Y 1 mutants having C-terminal truncations of different lengths [14].…”

The Peptide YY-Preferring Receptor Mediating Inhibition of Small Intestinal Secretion Is a Peripheral Y2Receptor: Pharmacological Evidence and Molecular Cloning

“…The inhibitory effects on cAMP production (Servin et al, 1989) and electrolyte secretion (Laburthe et al, 1982;Voisin et al, 1990;Eto et al, 1997) in intestine were also shown to be PYY-preferring with PYY being more potent than NPY. The PYY preference has recently been claimed as being a common characteristics of receptors in gastrointestinal epithelia (Holliday et al, 2000). Although characterized at the biochemical level as a 44-kDa glycoprotein (Voisin et al, 1991), the intestinal PYY receptor has not been yet cloned.…”