Abstract
Mercury (Hg) is a global environmental pollutant that affects human and ecosystem health. With the aim of exploring the Hg-induced protein modifications, intact human erythrocytes were exposed to HgCl2 (1–60 µM) and cytosolic and membrane proteins were analyzed by SDS-PAGE and AU-PAGE. A spectrofluorimetric assay for quantification of Reactive Oxygen Species (ROS) generation was also performed. Hg2+ exposure induces alterations in the electrophoretic profile of cytosolic proteins with a significant decrease in the intensity of the hemoglobin monomer, associated with the appearance of a 64 kDa band, identified as a mercurized tetrameric form. This protein decreases with increasing HgCl2 concentrations and Hg-induced ROS formation. Moreover, it appears resistant to urea denaturation and it is only partially dissociated by exposure to dithiothreitol, likely due to additional protein–Hg interactions involved in aggregate formation. In addition, specific membrane proteins, including band 3 and cytoskeletal proteins 4.1 and 4.2, are affected by Hg2+-treatment. The findings reported provide new insights into the Hg-induced possible detrimental effects on erythrocyte physiology, mainly related to alterations in the oxygen binding capacity of hemoglobin as well as decreases in band 3-mediated anion exchange. Finally, modifications of cytoskeletal proteins 4.1 and 4.2 could contribute to the previously reported alteration in cell morphology.
Highlights
Human exposure to heavy metals has increased significantly in the last decades as a result of a parallel increment in the use of these metals in industrial processes [1] and products [2,3]
We offer experimental evidence that both hemoglobin (Hb) as well as specific membrane proteins can be altered by HgCl2 treatment, as revealed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Acetic Acid Urea-Polyacrylamide Gel Electrophoresis (AU-PAGE)
In order to explore the possible interaction of Hg with erythrocyte proteins, intact human red blood cell (RBC)
Summary
Human exposure to heavy metals has increased significantly in the last decades as a result of a parallel increment in the use of these metals in industrial processes [1] and products [2,3]. Considerable attention has been focused on environmental pollution and the biological effects of these elements [4,5], including mercury (Hg) [6]. Hg contamination is extensive in all environmental compartments such as soil, air and water [7,8] and human exposure to Hg has increased with modern industrialization due to its anthropogenic emissions from fuel combustion, municipal incinerators and chemical industries. The contribution of environmental pollutants, including Hg, to the etiology of autism
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