Coexpression of Y₁, Y₂, and Y₄ Receptors in Smooth Muscle Coupled to Distinct Signaling Pathways

Abstract

Coexpression of Y 1 , Y 2 , and Y 4 receptors on smooth muscle cells was determined by reverse transcription-polymerase chain reaction, and the receptors were characterized by radioligand binding, selective receptor protection, and functional analysis of signaling pathways. (Eva et al., 1990;Lundell et al., 1995;Rose et al., 1995;Berglund et al., 2003;Rodriguez et al., 2003). The abbreviated Y designation reflects the large number of tyrosine residues (Y in the single-letter amino acid code) present in their endogenous ligands, neuropeptide Y (NPY), and the hormonal peptides, peptide YY (PYY) and pancreatic polypeptide (PP) (Blomqvist and Herzog, 1997;Berglund et al., 2003). A putative Y 3 receptor has not been cloned and remains a pharmacological entity based on the existence in some models of widely divergent responses to NPY and PYY . Y 4 binds preferentially PP, whereas Y 1 , Y 2 , and Y 5 bind preferentially NPY and PYY (Berglund et al., 2003). The pharmacological profile of Y 6 has not been accurately determined. The pharmacological profile of Y 2 receptors is distinctive with high affinities for NPY, PYY, long C-terminal fragments of NPY or PYY (e.g., NPY , and the selective, nonpeptide antagonist BIIE 0246 (Rose et al., 1995;Dumont et al., 2000 ; IP 3 , inositol 1,4,5-trsiphosphate; CCK-8, cholecystokinin octapeptide; D600, methoxyverapamil; MLCK, myosin light chain kinase; ML-9, 1-(5- (Krause et al., 1992;Doods et al., 1995;Wieland et al., 1995;Weinberg et al., 1996;Rodriguez et al., 2003 (Lundell et al., 1995).Y receptors are widely distributed in the central and peripheral nervous systems (Sundler et al., 1993;Lomax and Furness, 2000). Although typical responses have been ascribed to specific receptors, variability is common. Thus, inhibition of neurotransmitter release, a prototypical response mediated by Y 2 receptors in some tissues, (e.g., vas deferens) is mediated by Y 1 receptors in the enteric nervous system (Wahlestedt et al., 1986;Grider and Langdon, 2003). Expression of Y receptors in non-neural tissues has usually been surmised from pharmacological profiles and only rarely by precise receptor mapping. In gastrointestinal tissues, for example, the response to NPY, PYY, or PP is often a compound of nerve-mediated and direct effects that involve more than one receptor type, leading to divergent results and interpretations (Feletou et al., 1998;Pheng et al., 1999;Ferrier et al., 2000Ferrier et al., , 2002. Recent studies have attempted to facilitate the interpretation of pharmacological studies by measurement of Y receptor expression (Goumain et al., 1998). Analysis of receptor expression by RT-PCR in heterogeneous tissues can be useful in identifying which receptor types are not expressed, but it has obvious limitations in assigning expressed receptors to specific tissues or cell types. This is illustrated by several recent studies of Y receptor expression in rat colon, where there was complete agreement on expression of Y 4 receptors, and clear differences on expression of Y 1 , Y ...

Functional Selective Oxytocin-derived Agonists Discriminate between Individual G Protein Family Subtypes

“…These findings together indicate that ligands can discriminate different G i family members at a single GPCR. G i /G o -biased activity has been reported previously (47,48), but, to the best of our knowledge, this is the first clear example of ligands biased toward a single G i family member.…”

NPY Y1 Receptors Differentially Modulate GABAA and NMDA Receptors via Divergent Signal-Transduction Pathways to Reduce Excitability of Amygdala Neurons

“…The effect of NPY to reduce cAMP levels is well known (Hsieh et al, 2007;Misra et al, 2004;Sheriff et al, 2003;Zhang and Pandey, 2003). A reduction of cAMP has previously been implicated in enhancing GABA A currents (Kapur and Macdonald, 1996) and in reducing NMDA currents (Fourcaudot et al, 2008;Huang et al, 1993;Huang and Kandel, 1998;Zhang et al, 2011b) in various brain regions.…”

Pancreatic Polypeptide Is Recognized by Two Hydrophobic Domains of the Human Y4 Receptor Binding Pocket

“…Preparation of hY 4 R Mutants-The single mutations were inserted by site-directed mutagenesis into the protein sequence. Pfu Turbo DNA polymerase (Agilent) (2.5 units/l) was used as a reaction enzyme in combination with 10ϫ reaction buffer.…”

“…The NPYR is closely related to other class A GPCR families such as the neuropeptide FF receptor family and the orexin receptor family (3). NPY receptors are physiologically coupled to the G i or G o proteins; however, other reports show that rabbit Y 2 R and rabbit Y 4 R are also coupled to the G q protein, triggering an increase in inositol phosphate (4). These receptors are activated by the NPY family of peptide hormones, consisting of NPY, peptide YY (PYY), and pancreatic polypeptide (PP).…”

“…Residues located at extracellular regions of the hY 4 R, chosen according to their location in the receptor sequence and in comparative models of hY 4 R, were mutated to determine their role in hPP binding. Simultaneously, a set of hPP analogs was also developed to pinpoint specific interactions between hPP and hY 4 4 R binding pocket. Furthermore, hPP analogs with modifications in residues 27, 33, or 36 revealed these positions to be interaction partners with the receptor.…”