Phosphoproteomic analysis indicates that the B cell cytoskeleton is disrupted after exposure to mercury

Exposure to environmental mercury (Hg) currently may contribute to immune system dysfunction and autoimmune disease. In this study phosphoproteomic analysis was used to investigate the impact of Hg2+ on a B cell line. Treatments were with 0, 2, 5, 10, 20, 50 and 100 uM Hg2+. 1713 phosphoproteins and 1937 confidently localized phosphorylation sites were identified. 161 phosphoproteins responded to Hg2+ treatment (ANOVA, 10% FDR). Hg2+ at 50 and 100 uM stimulated Tyr phosphorylation on residues in the B-cell receptor complex as well as other systems. At 20 uM and below Hg2+ primarily caused hyperphosphorylation of pSer/Thr residues and affected cytoskeletal systems. Map Kinase 1 was exceptional as it was hyperphosphorylated at Tyr 185 following 20 uM and lower Hg2+ treatments. These results contribute novel insight into the mechanism for immune system disruption by Hg2+.