Inhibition of plasma membrane calcium pump by aurintricarboxylic acid

.ROSSI, JUAN PABLO F.C.; BRUNO CAMILA1, SOUTO-GUEVARA CECILIA1, DE SAUTU MARILINA, SAFFIOTI NICOLÁS, FERREIRA-GOMES MARIELA; ROSSI JUAN PABLO AND MANGIALAVORI IRENE

SAN LUIS

Congreso; 277. XLVIII Reunión Anual SAB, 27-29 Noviembre 2019. San Luis,; 2019

SOCIEDAD ARGENTINA DE BIOFÍSICA

Inhibition of plasmamembrane calcium pump by aurintricarboxylic acid Bruno Camila1, Souto-Guevara Cecilia1, deSautu Marilina, Saffioti Nicolás, Ferreira-Gomes Mariela; Rossi Juan Pablo andMangialavori Irene.  Instituto deQuímica y Fisicoquímica Biológicas. ?Prof.Paladini?. Departamento de QuímicaBiológica, Facultad de Farmacia y Bioquímica. Universidad de BuenosAires. BC and SGC contributedequally to this work Plasmamembrane calcium ATPases (PMCAs) are high-affinity calcium pumps that extrudecalcium from the cytosol to the extracellular medium. In humans, PMCAs areencoded by 4 independent genes termed PMCA1 to 4. PMCA1 and 4 are expressedubiquitously, whereas the expression of PMCA2 and 3 is restricted to specificcells and tissues. PMCA4 regulates calcium concentration within its vicinityand modulates the activity of its interacting partners. PMCA4is the isoform more abundant in hematopoietic tissue. PMCA4 has emerged as animportant negative regulator of several pathophysiological processes thatinvolve angiogenesis, increasing the interest on its pharmacological blockadeto potentiate the efficiency of therapeutic strategies. Mohamed et al (2013)1showed that low concentrations of aurintricarboxylic acid (ATA) stronglyinhibit the calcium extrusion activity of PMCA4 in HEK cells without affectingthe activity of PMCA1 or other major pumps. Recently, Kurasamy et al (2017)2have showed that ATA inhibits PMCA4 in endothelial cells triggering a markedincrease in cell motility and blood vessel formation. However, the PMCAinhibition mechanism by ATA remains unknown. Theaim of this study was to characterize the effect of ATA on PMCA from humanerythrocytes (ePMCA), where about 80% is PMCA4 and 20% PMCA1. Our currentresults show that: (1) ATA inhibited Ca2+-ATPase activity ofpurified ePMCA with an apparent Ki = 100 nM; (2) The value ofKi depended on Mg2+ concentration; (3) The valueof Ki did not modify by ATP concentration; (4) When ePMCA isin its native membrane environment, the value of Ki increasedmore than twenty times. Ourresults suggest that ATA does not bind to the ATP binding site of ePMCA and Mg2+is necessary to the total inhibition of Ca2+-ATPase activity.   1 Mohamed TM, Abou-LeisaR, (?.) Oceandy D. (2013) J Mol Cell Cardiol. 63:57-68. 2 Kurusamy S, López-Maderuelo D, (?)Armesilla AL. (2017) JMol Cell Cardiol109: 38-47  Thiswork was supported by Agencia Nacional de Promoción Científica y Tecnológica(PRESTAMO BID-PICT-2017-2615 and 2015-0067) and Universidad de Buenos Aires(UBACYT- 20020130100254B