Differences in the mechanisms of inhibition of aluminium on the plasma membrane and the sarcoplasmic reticulum calcium pumps

DE SAUTU, M., SAFFIOTI, N., FERREIRA-GOMES, M., RINALDI D. ROSSI RC ROSSI, JPFC AND MANGIALAVORI, IC.

San Miguel de Tucumán

Congreso; 242. III Latin American Federation of Biophysical Societies (LAFeBS) IX IberoAmerican Congress of Biophysics XLV Reunion Anual SAB 2016; 2016

Sociedad Argentina de Biofísica

Tipo: pósterTópico:       Proteins, Structure and Function     Aluminium inhibits the plasma membrane and thesarcoplasmic reticulum calcium pumps by different mechanismsDe Sautu, M., Saffioti, N.,Ferreira-Gomes, M., Rinaldi D. Rossi RC Rossi,JPFC and Mangialavori, IC. IQUIFIB- Dr. Paladini -Departamento de Química Biológica, Universidad deBuenos Aires  Aluminium (Al3+) is a metal widelydistributed in the environment and seems to be involved with thepathophysiology of neurodegenerative disorders, such as Parkinsonism dementiaand Alzheimer?s disease. Several mechanisms explain its neurotoxicity as the damageto the glycolytic metabolism, lipid peroxidation, protein modifications andchanges in the cellular calcium homeostasis. The aim of this work was to study the inhibitorymechanism of Al3+ of the plasma membrane (PMCA) and the sarcoplasmicreticulum (SERCA) Ca2+-ATPases, which regulate the cytoplasmiccalcium concentration. For this reason, we performed measurements of the effectof Al3+ on purified preparations of PMCA and SERCA. Further, wemeasured the effect of Al3+ on intracellular calcium concentrationin HEK293 cells using fluorescent probes. Our results show that: (1) Al3+ inhibitsCa2+-ATPase activity of both enzymes with similar apparent affinity;(2) In the presence of ATP, Al3+ associates reversibly to SERCA, althoughin PMCA the enzyme remains inhibited. (3) In the presence of Al3+,the apparent affinity for Ca2+ of SERCA decreased, while theapparent affinity remains constant for PMCA; (4) Al3+ increases thephosphorylated intermediate level (EP) of PMCA while in SERCA decreases; (5) Al3+inhibits the calcium efflux mediated by PMCA in HEK293 cells, suggesting an in vivo action; (6) Preliminary studiesusing fluorescence microscopy and Lumogallion as a probe, suggest that Al3+could be located in the membrane of HEK293 cells.This work demonstrates for the first time differentinhibitory mechanisms of action of Al3+ on these two Ca2+-transportATPases that changes the cellular calcium homeostasis. With grants of ANPCYT, CONICET, UBACYT