Alpha-synuclein Affects Certain Iron Transporters of BV2 Microglia Cell through its ferric reductase activity

Objective: Alpha-synuclein (α-syn) is a major component of lewy bodies, which is biomarker of Parkinson's disease (PD). It accumulates in substantia nigra pars compacts (SNpc) to form insoluble aggregates and cause neurotoxicity, which is often accompanied by iron deposition. Method: We compared the iron reductase activity between monomeric α-syn (M-α-syn) and oligomeric α-syn (O-α-syn), investigated the effect of α-syn on iron metabolism of BV2 microglia cells as well. Results: α-syn had ferric reductase activity, and O-α-syn had stronger enzyme activity than M-α-syn. M-α-syn upregulated iron uptake protein, divalent metal transporter1 (DMT1) expression and iron influx, but did not regulate iron release protein, ferroportin1 (FPN1) expression and iron efflux. O-α-syn elevated the expression of both DMT1 and FPN1, thus increased the iron influx and efflux in BV2 microglial cells, but the expressions of iron regulatory protein1 (IRP1) and hypoxia inducible factor2α (HIF-2α) had no significant change. Moreover, both M-α-syn and O-α-syn could increase the mRNA expressions of TNF-α and IL-1β in BV2 microglia cells. Conclusion: Both types of α-syn can activate microglia, which leads to increased expressions of pro-inflammatory factors. α-syn can affect DMT1 and FPN1 expressions in BV2 microglia cells, which might be through its ferric reductase activity.