McDermott JR, Geng X, Jiang L, Gálvez-Peralta M, Chen F, Nebert DW, Liu Z. Zinc- and bicarbonate-dependent ZIP8 transporter mediates selenite uptake.
Oncotarget 2018;
7:35327-40. [PMID:
27166256 PMCID:
PMC5085232 DOI:
10.18632/oncotarget.9205]
[Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2015] [Accepted: 04/11/2016] [Indexed: 12/26/2022] Open
Abstract
Selenite (HSeO3−) is a monovalent anion of the essential trace element and micronutrient selenium (Se). In therapeutic concentrations, HSeO3− has been studied for treating certain cancers, serious inflammatory disorders, and septic shock. Little is known, however, about HSeO3− uptake into mammalian cells; until now, no mammalian HSeO3− uptake transporter has been identified. The ubiquitous mammalian ZIP8 divalent cation transporter (encoded by the SLC39A8 gene) is bicarbonate-dependent, moving endogenous substrates (Zn2+, Mn2+, Fe2+ or Co2+) and nonessential metals such as Cd2+ into the cell. Herein we studied HSeO3− uptake in: human and mouse cell cultures, shRNA-knockdown experiments, Xenopus oocytes, wild-type mice and two transgenic mouse lines having genetically altered ZIP8 expression, and mouse erythrocytes ex vivo. In mammalian cell culture, excess Zn2+ levels and/or ZIP8 over-expression can be associated with diminished viability in selenite-treated cells. Intraperitoneal HSeO3− causes the largest ZIP8-dependent increases in intracellular Se content in liver, followed by kidney, heart, lung and spleen. In every model system studied, HSeO3− uptake is tightly associated with ZIP8 protein levels and sufficient Zn2+ and HCO3− concentrations, suggesting that the ZIP8-mediated electroneutral complex transported contains three ions: Zn2+/(HCO3−)(HSeO3−). Transporters having three different ions in their transport complex are not without precedent. Although there might be other HSeO3− influx transporters as yet undiscovered, data herein suggest that mammalian ZIP8 plays a major role in HSeO3− uptake.
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