Proteome changes in methylmercury-exposed mouse primary cerebellar granule neurons and astrocytes

Methylmercury (MeHg) is a neurotoxicant, with the cerebellum as the main target of toxicity; however, the toxic effects of MeHg on specific cell types remain unclear. Here, primary cerebellar granule neurons (CGNs) and cerebellar astrocytes were isolated and analyzed for total mercury accumulation, cellular reactive oxygen species (ROS) production, and whole-cell proteome expression after exposure to 0-10 μM MeHg for 24 h. Intracellular mercury and ROS levels showed dose-dependent increases. Mercury accumulation was greater in CGNs than astrocytes. The proteomic analysis identified a total of 1966 and 3214 proteins in CGNs and astrocytes, among which 183 and 262 proteins were differentially expressed after mercury exposure, respectively. Enrichment analysis revealed mitochondrial-associated organelles as the main targets of MeHg in both cell types. Whereas multiple functions/pathways were affected in CGNs, the oxidation-reduction process was the most significantly changed function/pathway in astrocytes. CGNs were more sensitive to MeHg-mediated neurotoxicity than astrocytes. The two cell types showed distinct mechanistic responses to MeHg. In astrocytes, the mitochondrion was the primary target of toxicity, resulting in increases in oxidation-reduction process responses. In CGNs, the neurotrophin signaling pathway, cytoskeleton, cAMP signaling pathway, and thyroid hormone signaling pathway were affected.