RESUMEN
Bitter taste receptors, particularly TAS2R14, play central roles in discerning a wide array of bitter substances, ranging from dietary components to pharmaceutical agents1,2. TAS2R14 is also widely expressed in extragustatory tissues, suggesting its extra roles in diverse physiological processes and potential therapeutic applications3. Here we present cryogenic electron microscopy structures of TAS2R14 in complex with aristolochic acid, flufenamic acid and compound 28.1, coupling with different G-protein subtypes. Uniquely, a cholesterol molecule is observed occupying what is typically an orthosteric site in class A G-protein-coupled receptors. The three potent agonists bind, individually, to the intracellular pockets, suggesting a distinct activation mechanism for this receptor. Comprehensive structural analysis, combined with mutagenesis and molecular dynamic simulation studies, elucidate the broad-spectrum ligand recognition and activation of the receptor by means of intricate multiple ligand-binding sites. Our study also uncovers the specific coupling modes of TAS2R14 with gustducin and Gi1 proteins. These findings should be instrumental in advancing knowledge of bitter taste perception and its broader implications in sensory biology and drug discovery.
Asunto(s)
Ácidos Aristolóquicos , Colesterol , Ácido Flufenámico , Receptores Acoplados a Proteínas G , Gusto , Humanos , Ácidos Aristolóquicos/metabolismo , Ácidos Aristolóquicos/química , Ácidos Aristolóquicos/farmacología , Sitios de Unión/efectos de los fármacos , Colesterol/química , Colesterol/metabolismo , Colesterol/farmacología , Microscopía por Crioelectrón , Ácido Flufenámico/química , Ácido Flufenámico/metabolismo , Ácido Flufenámico/farmacología , Subunidades alfa de la Proteína de Unión al GTP Gi-Go/química , Subunidades alfa de la Proteína de Unión al GTP Gi-Go/metabolismo , Ligandos , Modelos Moleculares , Simulación de Dinámica Molecular , Mutación , Receptores Acoplados a Proteínas G/agonistas , Receptores Acoplados a Proteínas G/genética , Receptores Acoplados a Proteínas G/metabolismo , Receptores Acoplados a Proteínas G/ultraestructura , Gusto/efectos de los fármacos , Gusto/fisiología , Transducina/química , Transducina/metabolismoRESUMEN
An asymmetric bi-nuclear copper(II) complex with both cytotoxic and immunogenic activity towards breast cancer stem cells (CSCs) is reported. The bi-nuclear copper(II) complex comprises of two copper(II) centres bound to flufenamic acid and 3,4,7,8-tetramethyl-1,10-phenanthroline. The bi-nuclear copper(II) complex exhibits sub-micromolar potency towards breast CSCs grown in monolayers and three-dimensional cultures. Remarkably, the bi-nuclear copper(II) complex is up to 25-fold more potent toward breast CSC mammospheres than salinomycin (a gold standard anti-breast CSC agent) and cisplatin (a clinically administered metallodrug). Mechanistic studies showed that the bi-nuclear copper(II) complex readily enters breast CSCs, elevates intracellular reactive oxygen species levels, induces apoptosis, and promotes damage-associated molecular pattern release. The latter triggers phagocytosis of breast CSCs by macrophages. As far as we are aware, this is the first report of a bi-nuclear copper(II) complex to induce engulfment of breast CSCs by immune cells.