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

DEBORA E. RINALDI; MARIELA FERREIRA GOMES; IRENE MANGIALAVORI; AMABLE G; OSVALDO REY; JUAN PABLO ROSSI

Congreso; LI Reunión Anual de la Sociedad Argentina de Investigaciones Bioquímicas (SAIB).; 2015

Green tea polyphenols are natural plant flavonoids and comprise many types of catechins. Epigallocatechin gallate (EGCg) is the major polyphenol component and primarily responsible for the green tea effects. EGCgbeneficial effects include mainly antioxidant, anti-inflammatory and neuroprotective effects.Previous studies showed that EGCg inhibits the Na+,K+-ATPase activity by reducing the rate of the E1P to E2P transition through interaction with plasma membrane phospholipids.The purpose of this work is to investigate the effect of EGCgon thePlasma membrane Ca2+- ATPase (PMCA) as anothermember of the P-type ATPases family.We examined the effects of EGCg on the PMCA activityby using vesicles from human red blood cells. The EGCg showed an inhibitory effect on the Ca2+ ATPase activity in a dose-dependent manner with K0.5values of 3.5 M. This valuewas similar to those found for 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 bycytoplasmic free Ca2+measurements using Fluo4-AM. EGCg decreasedthe rate of removal of Ca2+ in HEK293 cellswith respect to the control, suggesting that those systems that remove calciumincluding PMCA would be affected, through a process that remains to be determined.