d-Galactose Decreases Anion Exchange Capability through Band 3 Protein in Human Erythrocytes

Abstract

d-Galactose (d-Gal), when abnormally accumulated in the plasma, results in oxidative stress production, and may alter the homeostasis of erythrocytes, which are particularly exposed to oxidants driven by the blood stream. In the present investigation, the effect of d-Gal (0.1 and 10 mM, for 3 and 24 h incubation), known to induce oxidative stress, has been assayed on human erythrocytes by determining the rate constant of SO42− uptake through the anion exchanger Band 3 protein (B3p), essential to erythrocytes homeostasis. Moreover, lipid peroxidation, membrane sulfhydryl groups oxidation, glycated hemoglobin (% A1c), methemoglobin levels (% MetHb), and expression levels of B3p have been verified. Our results show that d-Gal reduces anion exchange capability of B3p, involving neither lipid peroxidation, nor oxidation of sulfhydryl membrane groups, nor MetHb formation, nor altered expression levels of B3p. d-Gal-induced %A1c, known to crosslink with B3p, could be responsible for rate of anion exchange alteration. The present findings confirm that erythrocytes are a suitable model to study the impact of high sugar concentrations on cell homeostasis; show the first in vitro effect of d-Gal on B3p, contributing to the understanding of mechanisms underlying an in vitro model of aging; demonstrate that the first impact of d-Gal on B3p is mediated by early Hb glycation, rather than by oxidative stress, which may be involved on a later stage, possibly adding more knowledge about the consequences of d-Gal accumulation.

d‐Galactose induced early aging in human erythrocytes: Role of band 3 protein

“…In these experimental conditions, the rate constant for SO 4 2− uptake was accelerated and, in parallel, SO 4 2− uptake was significantly reduced (Figure 1 and Table 1). This finding appears to be in disagreement with what was reported by our group in a recent study (Remigante et al, 2020), where the exposure of erythrocytes to 10 mmol/L D-Gal for 24 h has been observed to induce a reduction (0.051 ± 0.001 in 19.60 min) of the rate constant for SO 4 2− uptake, not accompanied by lipid peroxidation, oxidation of -SH membrane groups, alteration of GSH/GSSG ratio, or MetHb formation (Remigante et al, 2020).…”

“…Similar to what was performed in the previous investigation (Remigante et al, 2020) and to better explain the altered functional mechanism observed in the present experiments, lipid peroxidation and oxidation of membrane -SH groups, mainly belonging to B3p (Roy et al, 2005) & Zakaria, 2019). These findings suggest that 25 mmol/L D-Gal represents a threshold value for differential effects on B3p.…”

“…Similar to what was performed in the previous investigation (Remigante et al, 2020) and to better explain the altered functional mechanism observed in the present experiments, lipid peroxidation and oxidation of membrane -SH groups, mainly belonging to B3p (Roy et al, 2005) On the basis of our results, we suggest that this in vitro model of aging induced by the D-Gal application may give the chance to study the impact of aging at early stages, as revealed by the mechanism through which B3p transport efficiency is affected. The present in vitro model of aging shows that B3p efficiency is affected by the contribution of slight oxidative events, putatively targeting Hb.…”

Role of SLC4 and SLC26 solute carriers during oxidative stress

“…82 OS plays a fundamental role in the pathophysiology of galactosemia, which is also characterized by the formation of glycated haemoglobin. [82][83][84] Remigante et al 85 have reported that the rate constant for SO 4 2− uptake via…”

Cellular Oxidative Stress

“…Despite d-Gal being known to induce oxidative stress, exposure of erythrocytes to relatively low (0.1–10 mM) d-Gal concentrations led to a reduced anion exchange capability independent from oxidative stress, but rather linked to glycated Hb production. This study sheds light on the early effects of excessive d-Gal on membrane transport systems and possible complications related to undiagnosed galactosemia [ 2 ].…”