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Toxicol Appl Pharmacol. 2014 Apr 1;276(1):47-54. doi: 10.1016/j.taap.2014.01.002. Epub 2014 Jan 14.

A systems toxicology approach identifies Lyn as a key signaling phosphoprotein modulated by mercury in a B lymphocyte cell model.

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Institute of Environmental Health Sciences, Wayne State University, Detroit, MI, USA.
Department of Pediatrics, Wayne State University, Detroit, MI, USA.
Department of Immunology and Microbiology, Wayne State University, Detroit, MI, USA.
Department of Immunology and Microbiology, Wayne State University, Detroit, MI, USA. Electronic address:


Network and protein-protein interaction analyses of proteins undergoing Hg²⁺-induced phosphorylation and dephosphorylation in Hg²⁺-intoxicated mouse WEHI-231 B cells identified Lyn as the most interconnected node. Lyn is a Src family protein tyrosine kinase known to be intimately involved in the B cell receptor (BCR) signaling pathway. Under normal signaling conditions the tyrosine kinase activity of Lyn is controlled by phosphorylation, primarily of two well known canonical regulatory tyrosine sites, Y-397 and Y-508. However, Lyn has several tyrosine residues that have not yet been determined to play a major role under normal signaling conditions, but are potentially important sites for phosphorylation following mercury exposure. In order to determine how Hg²⁺ exposure modulates the phosphorylation of additional residues in Lyn, a targeted MS assay was developed. Initial mass spectrometric surveys of purified Lyn identified 7 phosphorylated tyrosine residues. A quantitative assay was developed from these results using the multiple reaction monitoring (MRM) strategy. WEHI-231 cells were treated with Hg²⁺, pervanadate (a phosphatase inhibitor), or anti-Ig antibody (to stimulate the BCR). Results from these studies showed that the phosphoproteomic profile of Lyn after exposure of the WEHI-231 cells to a low concentration of Hg²⁺ closely resembled that of anti-Ig antibody stimulation, whereas exposure to higher concentrations of Hg²⁺ led to increases in the phosphorylation of Y-193/Y-194, Y-501 and Y-508 residues. These data indicate that mercury can disrupt a key regulatory signal transduction pathway in B cells and point to phospho-Lyn as a potential biomarker for mercury exposure.


Autoimmune disease; B cell; Lyn; Mercury; Multiple reaction monitoring; Phosphoproteomics

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