Molecular mechanism of the metallothionein gene expression mediated by metal-responsive transcription factor 1

Abstract

Metal-responsive transcription factor 1 (MTF-1) is essential for activating transcription of the metallothionein genes in response to multiple species of heavy metals by binding to the metal-responsive element (MRE) located in the upstream region of the genes. In contrast, MTF-1 binding to the MRE in vitro is induced only by zinc ions, suggesting that MTF-1 acts as a zinc sensor protein. Although the mechanism allowing such a zinc-responsive factor to respond to various metal species in vivo remains ambiguous, recent information regarding the metal response of MTF-1 and the genes expressed downstream of MTF-1 provides important clues to unraveling the intrinsic mechanism and the biological significance of the MTF-1 functions in vivo.