Induction of Metallothionein mRNA in HeLa Cells by Dexamethasone and by Heavy Metals

Synthesis of metallothionein, a cysteine-rich heavy metal binding protein, is induced in cultured HeLa cells both by the heavy metals Cd2+, Zn2+ and Cu2+, and by the glucocorticoid hormone dexamethasone. The accumulation of [35S]cysteine-labeled metallothionein and the amount of translatable metallothionein mRNA show identical concentration dependences in response to dexamethasone treatment and in response to zinc exposure. Induction of translatable metallothionein mRNA is rapid in response to both the metal and glucocorticoid inducers. Increased synthesis and accumulation of metallothionein in response to either metal or glucocorticoid exposure is regulated by the level of translatable metallothionein mRNA in HeLa cells.