| Abstract
| - The nuclear and steroid hormone receptors function as ligand-dependent transcriptional regulatorsof diverse sets of genes associated with development and homeostasis. Mutations to the vitamin D receptor(VDR), a member of the nuclear and steroid hormone receptor family, have been linked to human vitaminD-resistant rickets (hVDRR) and result in high serum 1,25(OH)2D3 concentrations and severe boneunderdevelopment. Several hVDRR-associated mutants have been localized to the ligand binding domainof VDR and cause a reduction in or loss of ligand binding and ligand-dependent transactivation function.The missense mutation Arg274 → Leu causes a >1000-fold reduction in 1,25(OH)2D3 responsiveness andis, therefore, no longer regulated by physiological concentrations of the hormone. In this study, computer-aided molecular design was used to generate a focused library of nonsteroidal analogues of the VDRagonist LG190155 that were uniquely designed to complement the Arg274 → Leu associated with hVDRR.Half of the designed analogues exhibit substantial activity in the hVDRR-associated mutant, whereas noneof the structurally similar control compounds exhibited significant activity. The seven most active designedanalogues were more than 16 to 526 times more potent than 1,25(OH)2D3 in the mutant receptor (EC50 =3.3−121 nM). Significantly, the analogues are selective for the nuclear VDR and did not stimulate cellularcalcium influx, which is associated with activation of the membrane-associated vitamin D receptor.
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