Inhibition of the Plasma membrane Ca2+-ATPase by Epigallocatechin-3-gallate

RINALDI, D.E; FERREIRA GOMES, M; MANGIALAVORI, I. .; AMABLE, G; REY, O; ROSSI, J.P.

Mar del Plata

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

SAIB

Green tea polyphenols are natural plant flavonoids and comprise many types of catechin. Among them, epigallocatechin gallate (EGCg) is the major polyphenol component and primarily responsible for the green tea effect. The beneficial effects of EGCg include antioxidant, anticarcinogenic, anti-inflammatory properties and neuroprotective effects.Previous studies have shown that EGCg inhibits the Na+,K+-ATPase activity by reducing the rate of the E1P to E2P transition through interaction with plasma membrane phospholipid. The purpose of this work is to investigate the effect of EGCg on the Plasma membrane Ca2+- ATPase (PMCA) as a member of the P-type ATPases family.We examined the effects of EGCg on the activity of the PMCA by using vesicles from human red cells. The EGCg showed an inhibitory effect on the Ca2+ ATPase activity in a dose-dependent manner with K0.5 values of 3.5 M. Inhibition by EGCg of the PMCA was similar to that of the Na+, K+- ATPase.One biological action attributed to EGCg is the ability to influence intracellular Ca2+ in both non-excitable and excitable cells. We characterized EGCg-regulated Ca2+ signaling by cytoplasmic free Ca2+ measurements using Fluo4-AM. EGCg decreased the rate of removal of Ca2+ in HEK293 cells respect to the control, suggesting that those systems that remove calcium including the PMCA would be affected, through a process that remains to be determined.