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Peroxisome Proliferation-Activated Receptor δ Agonist GW0742 Interacts Weakly with Multiple Nuclear Receptors, Including the Vitamin D Receptor

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journal contribution
posted on 18.06.2013, 00:00 by Premchendar Nandhikonda, Adam Yasgar, Athena M. Baranowski, Preetpal S. Sidhu, Megan M. McCallum, Alan J. Pawlak, Kelly Teske, Belaynesh Feleke, Nina Y. Yuan, Chinedum Kevin, Daniel D. Bikle, Steven D. Ayers, Paul Webb, Ganesha Rai, Anton Simeonov, Ajit Jadhav, David Maloney, Leggy A. Arnold
A high-throughput screening campaign was conducted to identify small molecules with the ability to inhibit the interaction between the vitamin D receptor (VDR) and steroid receptor coactivator 2. These inhibitors represent novel molecular probes for modulating gene regulation mediated by VDR. Peroxisome proliferator-activated receptor (PPAR) δ agonist GW0742 was among the identified VDR–coactivator inhibitors and has been characterized herein as a pan nuclear receptor antagonist at concentrations of >12.1 μM. The highest antagonist activity for GW0742 was found for VDR and the androgen receptor. Surprisingly, GW0742 behaved as a PPAR agonist and antagonist, activating transcription at lower concentrations and inhibiting this effect at higher concentrations. A unique spectroscopic property of GW0742 was identified as well. In the presence of rhodamine-derived molecules, GW0742 increased the fluorescence intensity and level of fluorescence polarization at an excitation wavelength of 595 nm and an emission wavelength of 615 nm in a dose-dependent manner. The GW0742-inhibited NR–coactivator binding resulted in a reduced level of expression of five different NR target genes in LNCaP cells in the presence of agonist. Especially VDR target genes CYP24A1, IGFBP-3, and TRPV6 were negatively regulated by GW0742. GW0742 is the first VDR ligand inhibitor lacking the secosteroid structure of VDR ligand antagonists. Nevertheless, the VDR-meditated downstream process of cell differentiation was antagonized by GW0742 in HL-60 cells that were pretreated with the endogenous VDR agonist 1,25-dihydroxyvitamin D3.