RESUMEN
The progesterone receptor is able to bind to a large number and variety of ligands that elicit a broad range of transcriptional responses ranging from full agonism to full antagonism and numerous mixed profiles inbetween. We describe here two new progesterone receptor ligand binding domain x-ray structures bound to compounds from a structurally related but functionally divergent series, which show different binding modes corresponding to their agonistic or antagonistic nature. In addition, we present a third progesterone receptor ligand binding domain dimer bound to an agonist in monomer A and an antagonist in monomer B, which display binding modes in agreement with the earlier observation that agonists and antagonists from this series adopt different binding modes.
Asunto(s)
Receptores de Progesterona/agonistas , Receptores de Progesterona/antagonistas & inhibidores , Receptores de Progesterona/metabolismo , Animales , Sitios de Unión , Células CHO , Cricetinae , Cricetulus , Cristalografía por Rayos X/métodos , Dimerización , Diseño de Fármacos , Evaluación Preclínica de Medicamentos , Ligandos , Mifepristona/química , Modelos Moleculares , Conformación Molecular , Noretindrona/química , Progesterona/química , Unión Proteica , Conformación ProteicaRESUMEN
High-throughput screening of 3.87 million compounds delivered a novel series of non-steroidal GR antagonists. Subsequent rounds of optimisation allowed progression from a non-selective ligand with a poor ADMET profile to an orally bioavailable, selective, stable, glucocorticoid receptor antagonist.
Asunto(s)
Receptores de Glucocorticoides/antagonistas & inhibidores , Animales , Evaluación Preclínica de Medicamentos , Ensayos Analíticos de Alto Rendimiento , Humanos , Hidrocortisona/química , Microsomas/metabolismo , Ratas , Receptores de Glucocorticoides/metabolismo , Relación Estructura-Actividad , Sulfonamidas/síntesis química , Sulfonamidas/química , Sulfonamidas/farmacocinéticaRESUMEN
General anaesthetics exhibiting enantioselectivity afford valuable tools to assess the fundamental mechanisms underlying anaesthesia. Here, we characterised the actions of the R-(+)- and S-(-)-enantiomers of etomidate. In mice and tadpoles, R-(+)-etomidate was more potent (approximately 10-fold) than S-(-)-etomidate in producing loss of the righting reflex. In electrophysiological and radioligand binding assays, the enantiomers of etomidate positively regulated GABAA receptor function at anaesthetic concentrations and with an enantioselectivity paralleling their in vivo activity. GABA-evoked currents mediated by human recombinant GABAA receptors were potentiated by either R-(+)- or S-(-)-etomidate in a manner dependent upon receptor subunit composition. A direct, GABA-mimetic, effect was similarly subunit dependent. Modulation of GABA receptor activity was selective; R-(+)-etomidate inhibited nicotinic acetylcholine, or 5-hydroxytryptamine3 receptor subtypes only at supra-clinical concentrations and ionotropic glutamate receptor isoforms were essentially unaffected. Acting upon reticulothalamic neurones in rat brain slices, R-(+)-etomidate prolonged the duration of miniature IPSCs and modestly enhanced their peak amplitude. S-(-)-etomidate exerted qualitatively similar, but weaker, actions. In a model of locomotor activity, fictive swimming in Xenopus laevis tadpoles, R-(+)- but not S-(-)-etomidate exerted a depressant influence via enhancement of GABAergic neurotransmission. Collectively, these observations strongly implicate the GABAA receptor as a molecular target relevant to the anaesthetic action of etomidate.