Metallothionein is required for zinc-induced expression of the macrophage colony stimulating factor gene.
Macrophage colony stimulating factor (M-CSF) plays an important role in the proliferation and differentiation of mononuclear phagocytes. The present study investigates the effect of zinc on M-CSF expression in MC3T3-E1 and L929 cells. Zinc dose-dependently increased M-CSF mRNA levels. The time-course of zinc-induced M-CSF mRNA expression peaked at 6 h. Stability studies of mRNA using actinomycin D revealed that zinc does not affect M-CSF mRNA stability. We examined the function of the M-CSF gene promoter using a luciferase reporter assay. A construct containing the -467/+39 region of the promoter was upregulated by zinc. In the presence of cycloheximide, zinc did not induce a greater increase in the M-CSF mRNA than cycloheximide alone. To confirm the effect of MT on M-CSF mRNA expression, mouse lung fibroblasts (MLFs) were prepared from MT+/+ and MT-/- mice. Zinc induced an increase in the expression of M-CSF in MT+/+ MLFs, but this response was not evident in MT-/- MLFs. Moreover, overexpression of MT upregulated M-CSF mRNA expression as well as M-CSF secretion. Our findings suggest that MT expression mediates zinc regulation of M-CSF gene expression at the transcriptional level.
Department of Toxicology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka 565-0871, Japan.
Masako
M
Kanekiyo
Norio
N
Itoh
Atsuko
A
Kawasaki
Kimihiro
K
Matsuda
Tsuyoshi
T
Nakanishi
Keiichi
K
Tanaka
D000818:Animals; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D004789:Enzyme Activation; D005347:Fibroblasts; D017353:Gene Deletion; D005786:Gene Expression Regulation / Q000187:drug effects*; D016173:Macrophage Colony-Stimulating Factor / Q000096:biosynthesis / Q000235:genetics*; D008668:Metallothionein / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D011401:Promoter Regions, Genetic / Q000235:genetics; D020871:RNA Stability / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D015032:Zinc / Q000494:pharmacology*
D012333:RNA, Messenger; D016173:Macrophage Colony-Stimulating Factor; D008668:Metallothionein; D003513:Cycloheximide; D015032:Zinc