Natural flavonoids and calcium transport through biological membranes: molecular target and mechanisms of action

ONTIVEROS, M; RINALDI, D; PANTANO S; VIGIL, M; MARDER, M; ESPELT, M; MANGIALAVORI, I, ROSSI, RC, ROSSI, JP; FERREIRA-GOMES, M

Lima

Congreso; Revisiting the Central Dogma of Molecular Biology at the Single Molecule Level; 2019

Sociedad Peruana de Biofísica

Natural flavonoidsand calcium transport through biological membranes: molecular target andmechanisms of action? Ontiveros, M; Rinaldi, D; Pantano S; Vigil, M; Marder, M; Espelt, M;Mangialavori, I, Rossi, RC, Rossi, JP; Ferreira-Gomes, M Research onflavonoids from plant sources has recently sparked increasing interest becauseof their beneficial health properties. Different studies have shown thatflavonoids change the intracellular Ca2+ homeostasis linked toalterations in the function of mitochondria, Ca2+ channels and Ca2+pumps. These findings hint at plasma membrane Ca2+-ATPase (PMCA)involvement, as it transports Ca2+ actively to the extracellularmedium coupled to ATP hydrolysis, thus maintaining ion cellular homeostasis.The present study aims to investigate the effect of a flavonoid -quercetin- onPMCA both in isolated protein systems and in living cells,Results obtainedusing enzyme purified show that a quercetin-Mg2+complex inhibited PMCA and it did not avoid the PMCA phosphorylation, resultingin an increased level of phosphoenzyme in E1P conformation. On the otherhand, we performed docking assays of quercetin-Mg2+ as ligand andPMCA structure models as the receptor. PMCA model was obtained by homologymodelling on Na,K-ATPase crystallographic structure. Then, we propose aninteraction model between quercetin-Mg2+ complex and ATP bindingdomain in E1P conformation. To assesswhether these quercetin-Mg2+ effects on PMCA purified could occur inliving cells, we measured Ca2+ dynamics in different cell types. Resultsreveal that quercetin-Mg2+ treatment affected the cytoplasmic Ca2+dynamics probably because the PMCA activity is inhibited. Experiments performedwith human embryonic kidney cells, which transiently overexpress PMCA, showthat the quercetin-Mg2+ treatment induced the PMCA inhibition,suggesting that the effects observed on isolated system could occur in acomplex structure like a living cell.In conclusion,this work reveals a novel molecular mechanism through which quercetin-Mg2+inhibit PMCA, which leads to Ca2+ homeostasis and signalingalterations in the cell.