Effect of oxidative stress on SO4= uptake through band 3 protein in human erythrocytes

Human erythrocyte membrane consists of a lipid bilayer and integral proteins, amongst which Band 3 protein (B3p) playing a role in membrane deformability due to its cross link with cytoplasmic proteins, is responsible for Cl-/HCO3- exchange, reflecting on gas exchange efficiency. The effect of oxidative stress in terms of lipid peroxidation, -SH groups oxidation, anion exchange capability and phosphorylation of Tyrosine residues of Bp3, modulating its function, has been here considered. Oxidative conditions have been induced by exposure to either H2O2 or CdCl2 or NEM (N-ethylamelimide), with or without antioxidants such as Curcumin, Melatonin or MgCl2. The efficiency of B3p has been verified by measuring the rate constant for SO4= uptake, more easily estimated than Cl- transport, while oxidative status was assessed by determining levels of MDA (malonyldialdehyde), membrane –SH groups and intracellular GSH (reduced glutathione). B3p expression levels have been also measured. Our results show that the exposure to all oxidative compounds used for the present protocol reduced SO4= uptake via different mechanisms, as H2O2-induced damage was dependent neither on MDA production, nor on –SH groups and GSH levels reduction, contrarily to the other oxidants, while B3p expression levels were reduced after treatment with each oxidant. Moreover, phosphorylative pathways are involved in this inhibitory effect which is reversed by antioxidants. In conclusion, SO4= uptake may be suggested as a tool to monitor erythrocytes function under oxidative conditions possibly deriving from environment (food, water, enspired air) and B3p may be a candidate for pharmacological targeting against oxidative stress-related pathologies.