Neuropeptide Y Y4 Receptor Homodimers Dissociate upon Agonist Stimulation

Abstract

The pancreatic polypeptide-fold family of peptides consists of three 36-amino acid peptides, namely neuropeptide Y (NPY), peptide YY, and pancreatic polypeptide (PP). These peptides regulate important functions, including food intake, circadian rhythms, mood, blood pressure, intestinal secretion, and gut motility, through four receptors: Y1, Y2, Y4, and Y5. Additional receptor subtypes have been proposed based on pharmacology observed in native tissues. Recent studies with other Gprotein-coupled receptors have shown that homo-and heterodimerization may be important in determining receptor function and pharmacology. In the present study, the recently cloned rhesus (rh) Y4 receptor was evaluated using radioligand binding, and the pharmacological profile was found to be very similar to the human Y4 receptor. To study homo-and heterodimerization involving the Y4 receptor using bioluminescence resonance energy transfer 2 (BRET 2 ), the carboxy termini of the rhesus Y1, Y2, Y4, and Y5 receptors were fused to Renilla luciferase, and rhY4 was also fused to green fluorescent protein. Dimerization was also studied using Western blot analysis. Using both BRET 2 and Western analysis, we found that the rhY4 receptor is present at the cell surface as a homodimer. Furthermore, agonist stimulation using the Y4-selective agonists PP and 1229U91 can dissociate these dimers in a concentration-dependent manner. In contrast, rhY4 did not heterodimerize with other members of the NPY receptor family or with human opioid ␦ and receptors. Therefore, homodimerization is an important component in the regulation of the Y4 receptor.The neuropeptide Y (NPY) family of peptides consists of NPY, peptide YY (PYY), and pancreatic polypeptide (PP). These peptides regulate many important physiological functions, such as energy homeostasis, mood, and blood pressure. Currently, there are four cloned functional G-protein-coupled receptors (GPCRs), namely Y1, Y2, Y4, and Y5, that make up the NPY receptor family (see Berglund et al., 2003a for a review) in most mammals. All of these receptor subtypes are found in the brain as well as peripheral tissues. In addition, rabbits and mice have a functional y6 receptor, whereas in primates, this receptor subtype is not functional. NPY, PYY, and PP share a similar rank order of potencies at the Y1, Y2, and Y5 receptors: NPY Ϸ PYY Ͼ PP, whereas the Y4 receptor binds PP with higher affinity than it binds NPY and PYY and is thus regarded as the PP receptor. Like PP, the Y4 receptor is mainly found in the gut (Lundell et al., 1995), but binding sites for PP and Y4 mRNA have also been found in several rat brain regions, including hypothalamus and brainstem (Berglund et al., 2003a), suggesting that PP may also have direct effects on brain function. Besides the cloned NPY receptor family, several additional receptor subtypes have been proposed based on pharmacological evaluation of various tissue preparations. However, the first draft of the human genome did not provide evidence for any additional NPY receptor...

Evidence for the Existence of an Additional Class of Neuropeptide Y Receptor Sites in Rat Brain

“…receptors can form homodimers (Berglund et al, 2003b;Dinger et al, 2003). The possible existence of Y 1 and Y 5 heterodimers has also been suggested (Schober et al, 2003).…”

Neuropeptide Y stimulates retinal neural cell proliferation – involvement of nitric oxide

“…In fact, dimerization appears to be a universal phenomenon that provides an additional mechanism for modulation of receptor function, as well as for cross-talk between G protein coupled receptors (Gomes et al 2001). Regarding the NPY receptors, some functional and molecular studies suggested and demonstrated the formation of functional homo-or heterodimers (Berglund et al 2003;Dinger et al 2003;Silva et al 2003;Movafagh et al 2006). In the present study, the results suggest that NPY stimulates all the NPY receptors that will form an oligomer composed by Y 1 , Y 2 and/or Y 5 receptor, and when an antagonist of one of these receptors is present the effect mediated by NPY on this complex is completely blocked.…”

Dimerization of G protein-coupled receptors: New avenues for somatostatin receptor signalling, control and functioning

“…Furthermore, whereas binding of adenosine A1 and purine P2Y1 increases receptor oligomerization from a dimeric basal state (Yoshioka et al, 2002), binding of chemokines to CXCR4 promotes oligomerization from a monomeric basal state . On the other hand, it has also been reported that ligand binding induces the converse effect, so that binding of NPY, TRH and cholecystokinin to their respective receptors induces the dissociation of the assembled dimers/oligomers (Cheng and Miller, 2001;Latif et al, 2001;Berglund et al, 2003) which might be related to further endocytic processes (Gregan et al, 2004). Finally, dimeric state of some receptors remains constitutive and insensitive to ligand binding, as reported for the MTR1 receptor or the murine sst2 and sst3 (Pfeiffer et al, 2001;Ayoub et al, 2002).…”