Hsp40 Affinity Profiling Reveals Protein Destabilization Profiles Following Cellular Manganese and Vanadate Exposure

Heavy metals such as arsenic, lead, and cadmium are well-characterized toxicants and heavily regulated in ground and surface waters. However, even metals that are essential nutrients can be hazardous at higher concentrations. These transition metals may be less aggressively regulated due to the perception that they do not pose health risks even in the ppm range. One such metal is manganese, which is highly abundant in many drinking water sources in the United States despite emerging evidence that these metals can pose a threat. Vanadium is more tightly regulated due to its phosphatase inhibition, but also is commonly present in drinking water at > 100 ppb. Herein, we evaluate the effects of 100 M (~5 ppm) manganese (II) and vanadium (V) exposure on cellular proteostasis, using HEK293T cells. We find that cellular manganese exposure destabilizes hundreds of proteins. These include NKRF, a repressor of NF-kB, explaining the known inflammation phenotype associated with manganese exposure. Vanadium, by contrast, stabilizes RNA-binding splicing factors, explaining its known perturbation of RNA splicing. These studies provide evidence that manganese and vanadium can strongly perturb cellular processes, and provide motivation for further study.