title: The role of ZIP8 down-regulation in cadmium-resistant metallothionein-null cells.
abstract: The mechanisms of cellular cadmium uptake in mammalian cells remain obscure. To solve this problem, we established cadmium-resistant cells (A7 and B5) from metallothionein-null mouse cells, and found that cadmium accumulation was markedly suppressed in these cells. DNA microarray and real-time PCR analyses revealed that expressions of ZIP (Zrt-, Irt-related protein) 8 and ZIP14 were down-regulated in A7 and B5 cells. In particular, both mRNA and protein levels of ZIP8 were markedly suppressed in A7 and B5 cells. Introduction of short hairpin RNA (shRNA) of ZIP8 into parental cells reduced the accumulation of cadmium to about 35% of that of mock-transfected cells, whereas the introduction of shRNA of divalent metal transporter 1 hardly changed cadmium accumulation. Thus, the cadmium resistance in A7 and B5 cells may be conferred primarily by the down-regulation of ZIP8. In mouse tissues, high expression of ZIP8 was noted in the liver, kidney, lung and testis. These data suggest that ZIP8 plays an important role in cellular uptake of cadmium.
authors.affiliation: Tokushima Bunri University, Yamashiro-cho, Japan.
authors.forename: Hitomi
authors.initials: H
authors.lastname: Fujishiro
authors.forename: Satomi
authors.initials: S
authors.lastname: Okugaki
authors.forename: Keisuke
authors.initials: K
authors.lastname: Kubota
authors.forename: Tastuo
authors.initials: T
authors.lastname: Fujiyama
authors.forename: Hideki
authors.initials: H
authors.lastname: Miyataka
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Himeno
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D002104:Cadmium / Q000378:metabolism / Q000494:pharmacology*; D027682:Cation Transport Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000502:physiology; D002460:Cell Line; D015536:Down-Regulation; D004351:Drug Resistance / Q000502:physiology*; D008297:Male; D008668:Metallothionein / Q000096:biosynthesis / Q000502:physiology*; D051379:Mice; D008813:Mice, Inbred ICR; D009928:Organ Specificity; D012333:RNA, Messenger / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000099236:Solute Carrier Family 11, Member 2
chemical_list: D000911:Antibodies, Monoclonal; D002104:Cadmium; D027682:Cation Transport Proteins; D008668:Metallothionein; D012333:RNA, Messenger; D000099236:Solute Carrier Family 11, Member 2; C499256:Slc39a8 protein, mouse