Characterization of a Y1-preferring NPY/PYY receptor in HT-29 cells.

Abstract

Equilibrium binding studies showed that butyrate-treated HT-29 cells express a high-affinity 125I-labeled peptide YY (125I-PYY) binding site with a dissociation constant of 0.32 +/- 0.12 nM (mean +/- SE, n = 4). This site was Y1 preferring because neuropeptide Y (NPY) and the Y1-selective agonist [Leu31,Pro34]NPY were equipotent to PYY at displacing 125I-PYY; PYY-(13-36) and pancreatic polypeptide were > 1,000- and 10,000-fold less potent at displacing the radioligand. PYY and [Leu31,Pro34]NPY inhibited forskolin-stimulated adenosine 3',5'-cyclic monophosphate production 63% and 48%, respectively, with a half-maximal inhibitory concentration between 0.1 and 1.0 nM. PYY and [Leu31,Pro34]NPY had no effect on release of intracellular calcium alone or on the increase in intracellular calcium concentration caused by carbachol or neurotensin. Northern blot analysis of poly(A)+ RNA from HT-29 cells demonstrated a single transcript of 2.5 kb that hybridized to a human Y1-receptor cDNA probe. Sequence analysis of a reverse transcription-polymerase chain reaction product amplified with primers based on human Y1-receptor cDNA confirmed that these cells contained mRNA encoding the human Y1 receptor. These studies show that butyrate-treated HT-29 cells constitutively express the Y1-preferring NPY/PYY receptor and Y1 mRNA and provide a new model for studies of PYY-regulated epithelial cell function and tissue-specific expression of the human Y1-receptor gene.