69 research outputs found
Discovery of Small-Molecule Modulators of the Human Y<sub>4</sub> Receptor
<div><p>The human neuropeptide Y<sub>4</sub> receptor (Y<sub>4</sub>R) and its native ligand, pancreatic polypeptide, are critically involved in the regulation of human metabolism by signaling satiety and regulating food intake, as well as increasing energy expenditure. Thus, this receptor represents a putative target for treatment of obesity. With respect to new approaches to treat complex metabolic disorders, especially in multi-receptor systems, small molecule allosteric modulators have been in the focus of research in the last years. However, no positive allosteric modulators or agonists of the Y<sub>4</sub>R have been described so far. In this study, small molecule compounds derived from the Niclosamide scaffold were identified by high-throughput screening to increase Y<sub>4</sub>R activity. Compounds were characterized for their potency and their effects at the human Y<sub>4</sub>R and as well as their selectivity towards Y<sub>1</sub>R, Y<sub>2</sub>R and Y<sub>5</sub>R. These compounds provide a structure-activity relationship profile around this common scaffold and lay the groundwork for hit-to-lead optimization and characterization of positive allosteric modulators of the Y<sub>4</sub>R.</p></div
YR subtype selectivity of Y<sub>4</sub>R PAMs.
<p>Effect of 30 μM compound on the pEC<sub>50</sub> of Y-receptor agonists in COS-7 cells stable expressing a Y receptor subtype and the chimeric G-protein G<sub>α6qi4myr</sub>. Receptors were stimulated with their native ligands (Y<sub>1</sub>R, Y<sub>2</sub>R, Y<sub>5</sub>R: NPY; Y<sub>4</sub>R: PP). For Y-axis values, positive modulation represents an increase in the apparent potency (pEC<sub>50</sub>) of the native agonist and negative modulation represents a decrease in the apparent potency of the native agonist. Data represent the mean ± SEM of at least two independent experiments (for full concentration-response curves see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0157146#pone.0157146.s002" target="_blank">S2 Fig</a>) (*p < .05, ***p < .001 Bonferroni).</p
Distinct positions of the Niclosamide scaffold were shown to be relevant for Y<sub>4</sub>R PAM activity and YR selectivity.
<p>Substitutions in the benzoyl ring are important for Y<sub>4</sub>R potency (green), and offer a potential modification site (grey). Modifications in the aniline ring engender selectivity towards Y<sub>1</sub>R / Y<sub>5</sub>R subtype (red).</p
Y<sub>4</sub>R PAM activity of Niclosamide-like compounds.
<p>Potency of the Y<sub>4</sub>R PAMs was investigated with an inositol phosphate accumulation assay through potentiation of a PP EC<sub>20</sub> response. Data have been normalized to the maximum IP accumulation caused by the Y<sub>4</sub>R native ligand PP. Data represent the mean ± SEM of three independent experiments performed in duplicate.</p
Validation of Y<sub>4</sub>R PAM activity and subtype selectivity of initial Ca<sup>2+</sup>-flux-based screen hit compounds in an inositol phosphate accumulation assay.
<p>(A) Compound structures. (B) Effect of 10 μM compound on submaximal YR activation by 1 nM ligand, which represents EC<sub>20</sub>-EC<sub>60</sub> (Y<sub>1,2,5</sub>R: NPY; Y<sub>4</sub>R: PP). Data represent the mean ± SEM of two independent experiments each performed in quadruplicate (*** p ≤ .001 Bonferroni).</p
Structures of Y<sub>4</sub>R PAMs identified by HTS and inactive control compounds chosen for further characterization of Y<sub>4</sub>R PAM activity and YR subtype selectivity.
<p>Structures of Y<sub>4</sub>R PAMs identified by HTS and inactive control compounds chosen for further characterization of Y<sub>4</sub>R PAM activity and YR subtype selectivity.</p
Identification and Characterization of the First Selective Y<sub>4</sub> Receptor Positive Allosteric Modulator
The human Y<sub>4</sub> receptor
(Y<sub>4</sub>R) and its cognate
ligand, pancreatic polypeptide (PP), are involved in the regulation
of energy expenditure, satiety, and food intake. This system represents
a potential target for the treatment of metabolic diseases and has
been extensively investigated and validated in vivo. Here, we present the compound tBPC (<i>tert</i>-butylphenoxycyclohexanol),
a novel and selective Y<sub>4</sub>R positive allosteric modulator
that potentiates Y<sub>4</sub>R activation in G-protein signaling
and arrestin3 recruitment experiments. The compound has no effect
on the binding of the orthosteric ligands, implying its allosteric
mode of action at the Y<sub>4</sub>R and evidence for a purely efficacy-driven
positive allosteric modulation. Finally, the ability of tBPC to selectively
potentiate Y<sub>4</sub>R agonism initiated by PP was confirmed in
mouse descending colon mucosa preparations expressing native Y<sub>4</sub>R, demonstrating Y<sub>4</sub>R positive allosteric modulation
in vitro
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