. Differential inhibition of Plasma Membrane Ca2+-ATPase by quercetin and gossypin

GENTILE, L.; RINALDI, D.; MANGIALAVORI, I.; MARDER, M, ROSSI, JP; FERREIRA-GOMES, M.

Córdoba

Congreso; 243. LII Reunión de SAIB. 7 al 10 de noviembre de 2016. Universidad Nacional de Córdoba, Córdo-ba. Argentina.; 2016

Sociedad Argentina de Bioquímica y Biología Molecular

Tipo:PósterTópico:Proteins, Structure and Function o Membrane Transporters and Channels Quercetin and gossypin inhibit the PlasmaMembrane Ca2+-ATPase by different mechanismsOntiveros M.*; Gentile, L.*; Rinaldi, D.; Mangialavori, I.; Marder, M, Rossi,JP; Ferreira-Gomes, M.Instituto de Química y FisicoquímicaBiológicas. ?Prof. Paladini?. Departamento de Química Biológica, Facultad deFarmacia y Bioquímic,. Universidad de Buenos Aires.*Both authors contributed equally to this work. A large number of flavonoids, mostlyO-glycosides, are found in foods of plant origin. These compounds are believedto have cancer chemoprotective properties by triggering apoptosis through anincrease of cytosolic concentration of calcium ([Ca2+]c).The increase of [Ca2+]c could be due to the fact thatsome flavonoids inhibit specific Ca2+ removing systems, as thesarcoplasmic/endoplasmic reticulum Ca2+ ATPase and the plasmamembrane calcium ATPase (PMCA) [1, 2].Fromthe screening of Hibiscus flavonoids quercetin and gossypin emerged as the mostactive compounds on PMCA inhibitors. The aim of this work is to characterizethe effect these flavonoids on PMCA. We measured the Ca2+-ATPaseactivity in purified PMCA obtained from human erythrocytes and the [Ca2+]cin HEK293T cells. Resultsusing purified PMCA showed that (1) PMCA activity was inhibited by quercetinand gossypin with a K0.5 of0.34 ± 0.01 and 5.1 ± 1.0 µM, respectively; (2) the inhibition wasnoncompetitive with Ca2+; (3) both quercetin and gossypin affectedCaM activation, but quercetin produced a decrease in the apparent affinity forCaM while gossypin did not; (4) quercetin led to the increase of phosphoenzymelevel (EP) although gossypin induceda decrease. EP formed in the presenceof quercetin was dephosphorylated by ADP, suggesting that it could stabilize theE1P intermediate. These resultssuggest that gossypin could affect the binding of ATP while quercetin couldprevent the conformational change E1P→ E2P.InHEK293T cells quercetin and gossypin lowered the Ca2+ removal rate byPMCA compared to the control.Theseresults show that quercetin and gossypin inhibit PMCA by different mechanisms, changing the cellular calcium homeostasispossibly due to their different molecular structures.Withgrants of CONICET, ANPCYT and UBACYT[1]Ogunbayo et al. (2008) IUBMB Life.60, 853-858[2]Rinaldi et al. (2015) Latin AmericanCrosstalk in Biophysics and Physiology. SBF.Uy