Metalloproteomic Investigation of Hg-Binding Proteins in Renal Tissue of Rats Exposed to Mercury Chloride

Abstract

Results obtained from rat studies indicate that, even at low concentrations, mercurial species cause harmful effects on the kidneys, by inducing the nephrotic oxidative stress response. In the present work, Hg-associated proteins were identified as possible mercury-exposure biomarkers in rat kidneys exposed to low mercury chloride concentrations for 30 days (Hg-30) and 60 days (Hg-60), using metalloproteomic strategies. The renal proteomic profile was fractioned by two-dimensional electrophoresis and the mercury determinations in kidney samples, protein pellets and protein spots were performed using graphite furnace atomic absorption spectrometry. The characterization of Hg-associated protein spots and the analysis of differentially expressed proteins were performed by liquid chromatography, coupled with tandem mass spectrometry. Eleven Hg-associated protein spots with a concentration range of 79 ± 1 to 750 ± 9 mg kg−1 in the Hg-60 group were identified. The characterization and expression analyses allowed the identification of 53 proteins that were expressed only in the Hg-60 group, 13 “upregulated” proteins (p > 0.95) and 47 “downregulated” proteins (p < 0.05). Actin isoforms and hemoglobin subunits were identified in protein spots of the Hg-60 group, with mercury concentrations in the range of 138 to 750 mg kg−1, which qualifies these proteins as potential mercury-exposure biomarkers.

Toward a Mechanism-Driven Integrated Framework to Link Human Exposure to Multiple Toxic Metal(loid) Species with Environmental Diseases

“…In one noteworthy, recent study, rats were injected with Hg 2+ to deliver a total dose of 8.03 μg/kg over 60 days after which their kidneys were collected. The subsequent homogenization of the kidneys followed by the extraction of the cytosolic proteins allowed to analyze the obtained complex mixture by 2D-GE [ 111 ]. While this study revealed 13 upregulated proteins and 47 downregulated proteins compared with the control group, the excision of protein spots followed by their analysis for total Hg by graphite furnace atomic absorption spectrometry revealed 11 Hg-containing spots, some of which contained up to 750 ppm of Hg.…”