Zinc-induced activation of the human cytomegalovirus major immediate-early promoter is mediated by metallothionein and nuclear factor-kappaB.
We previously reported that major immediate-early promoter (MIEP) activity was regulated by intercellular zinc levels. In this report, we elucidate the mechanisms involved in this phenomenon. In luciferase reporter assays, zinc-induced activation of MIEP (-735/+62) was decreased with deletion of the promoter in stages, and MIEP (-117/+62) did not respond to zinc. The time course of the activity of MIEP responding to diethylenetriamine pentaacetic acid and zinc was not parallel with metallothionein (MT) promoter, which contains metal responsive elements. SV40 promoter that contains AP-1 binding sites, a candidate for the zinc-responsive motif in the MIEP, was not affected by zinc under our conditions. The activation of MIEP (-735/+62) by zinc was prevented with NF-kappaB decoy. When three kappaB motifs from the enhancer in the MIEP were inserted in the front of the zinc-nonresponsive MIEP (-117/+62), it became responsive to zinc. Moreover, overexpression of MT up-regulates the DNA binding of NF-kappaB and NF-kappaB-induced activation of transcription. These findings strongly suggest that MT and NF-kappaB act as mediator/regulator in zinc-induced activation of MIEP.
Kanekiyo
M
M
Department of Toxicology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka, 565-0871, Japan.
Itoh
N
N
Kawasaki
A
A
Tanaka
J
J
Nakanishi
T
T
Tanaka
K
K
D000956:Antigens, Viral / Q000235:genetics*; D001665:Binding Sites; D015153:Blotting, Western; D018929:Cell Culture Techniques; D002467:Cell Nucleus / Q000737:chemistry; D003587:Cytomegalovirus / Q000235:genetics*; D004247:DNA / Q000378:metabolism; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics*; D007700:Kinetics; D008668:Metallothionein / Q000235:genetics* / Q000494:pharmacology / Q000502:physiology; D016328:NF-kappa B / Q000235:genetics* / Q000502:physiology; D004369:Pentetic Acid / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D020218:Response Elements; D013539:Simian virus 40 / Q000235:genetics; D018808:Transcription Factor AP-1 / Q000378:metabolism; D015533:Transcriptional Activation; D015032:Zinc / Q000494:pharmacology*
D000956:Antigens, Viral; D017874:Immediate-Early Proteins; D016328:NF-kappa B; D018808:Transcription Factor AP-1; C044582:immediate-early proteins, cytomegalovirus; D004369:Pentetic Acid; D004247:DNA; D008668:Metallothionein; D015032:Zinc