Induction of metallothionein and stimulation of calcification by dexamethasone in cultured clonal osteogenic cells, MC3T3-E1.
To clarify the effects of dexamethasone (Dex) on metallothionein (MT) synthesis and calcification in osteoblastic cells, a clonal osteogenic cell line (MC3T3-E1) was used in the present study. Under culture conditions designed not to cause calcification, MT synthesis of cells at 3 days after inoculation increased with increasing concentration of Dex (2.5-50 nM) for a 24-h culture period. Cells at 6 or 9 days after inoculation also synthesized MT by a 24-h exposure to Dex. These show that undifferentiated osteoblasts have the ability to synthesize MT by Dex. Under culture conditions designed to cause calcification, cells at 6 days after inoculation were cultured with 50 nM Dex in the presence of 7 mM beta-glycerophosphate (beta-GP) for 7 days. Ca content of Dex-treated cells was about 7.5 times as high as that of untreated cells. Dex-treated cells showed a high activity of alkaline phosphatase (ALP). The Zn content of the MT fraction in Dex-treated cells was about 8 times as high as that of untreated cells. These results show that Dex has the ability to induce MT synthesis in osteoblastic cells and to cause a high calcification which is due at least partly to an enhanced activity of ALP.
Miyahara
T
T
Faculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, Japan.
Nemoto
M
M
Tukamoto
S
S
Yamada
H
H
Kozuka
H
H
Kuze
S
S
Sudo
H
H
Yamamoto
S
S
D000469:Alkaline Phosphatase / Q000032:analysis; D002113:Calcification, Physiologic / Q000187:drug effects*; D002454:Cell Differentiation; D002478:Cells, Cultured; D004247:DNA / Q000032:analysis; D003907:Dexamethasone / Q000494:pharmacology*; D008668:Metallothionein / Q000096:biosynthesis*; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism; D015032:Zinc / Q000378:metabolism
D003907:Dexamethasone; D004247:DNA; D008668:Metallothionein; D000469:Alkaline Phosphatase; D015032:Zinc