INHIBITION OF THE PLASMA MEMBRANE CA2+?ATPASE BY EPIGALLOCATECHIN 3?GALLATE

RINALDI, DEBORA; FERREIRA GOMES, MARIELA; MANGIALAVORI IRENE; AMABLE, GASTON; REY, OSVALDO; ROSSI, JUAN PABLO

Mar del Plata

Congreso; SAIB 2015. 51 Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2015

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Green tea polyphenols are natural plant flavonoids and comprise many types of catechins. Epigallocatechin 3?gallate(EGCg) is the major polyphenol component and primarily responsible for the green tea effects. EGCg beneficialeffects include mainly antioxidant, anti?inflammatory and neuroprotective effects. Previous studies showed thatEGCg inhibits the Na+,K+?ATPase activity by reducing the rate of the E1P to E2P transition through interaction withplasma membrane phospholipids. The purpose of this work is to investigate the effect of EGCg on the Plasmamembrane Ca2+? ATPase (PMCA) as another member of the P-type ATPases family. We examined the effects ofEGCg on the PMCA activity by using vesicles from human red blood cells. The EGCg showed an inhibitory effect onthe Ca2+?ATPase activity in a dose-dependent manner with K0.5 values of 3.5 μM. This value was similar to thosefound for Na+, K+?ATPase. One biological action attributed to EGCg is the ability to influence intracellular Ca2+ inboth non-excitable and excitable cells. We characterized EGCg-regulated Ca2+ signaling by cytoplasmic freeCa2+ measurements using Fluo4?AM. EGCg decreased the rate of removal of Ca2+ in HEK293 cells with respect tothe control, suggesting that those systems that remove calcium including PMCA would be affected, through a processthat remains to be determined.