Metal-dependent binding of a factor in vivo to the metal-responsive elements of the metallothionein 1 gene promoter.
AUTOR(ES)
Andersen, R D
RESUMO
Using the technique of genomic footprinting, we demonstrate cadmium-inducible protection from dimethyl sulfate (DMS) modification of guanine residues in vivo in five metal-responsive elements (MREs) in the promoter of the rat metallothionein 1 (MT-1) gene. We also identify a site of extreme DMS hyperreactivity which, like the MRE protection, occurs only after metal ion induction. With this hyperreactive site as an indicator, we can measure the kinetics of induction and deinduction. Changes in the intracellular metal ion concentrations are reflected in alterations in the reactivity with DMS of guanine residues in the MT-1 gene promoter. Lastly, for both control and metal-induced cells, we observe DMS protection and enhancement of a binding site (located 5' of the distal MRE) which is a consensus sequence for the Sp1 transcription factor. Transfection experiments with deletion mutations of a fusion gene construct indicate both that a sequence region which includes this GC box regulates the basal level of expression of the MT-1 gene and that increasing the number of MREs in the promoter increases the induced level of transcription. Our genomic footprinting and transfection data together suggest that (i) a transcription factor, possibly Sp1, plays an important role in regulating the basal level of expression of the MT-1 gene and (ii) metal induction involves the metal-dependent binding to a sequence-specific binding factor which responds to changes in intracellular metal ion levels.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=368011Documentos Relacionados
- Metal-dependent binding of a nuclear factor to the rat metallothionein-I promoter.
- Dynamics of the metal-dependent transcription factor complex in vivo at the mouse metallothionein-I promoter
- A metal-dependent DNA-binding protein interacts with a constitutive element of a light-responsive promoter.
- Building a metal-responsive promoter with synthetic regulatory elements.
- Metal-responsive elements act as positive modulators of human metallothionein-IIA enhancer activity.