Gene- and cell-type-specific effects of signal transduction cascades on metal-regulated gene transcription appear to be independent of changes in the phosphorylation of metal-response-element-binding transcription factor-1

Huimin Jiang, Kai Fu, Glen K. Andrews

Research output: Contribution to journalArticle

28 Scopus citations

Abstract

Post-translational modification of MTF-1 (metal-response-element-binding transcription factor-1) was suggested to play a role in its metalloregulatory functions. In the present study, pulse labelling and two-dimensional electrophoresis-Western blotting were used to demonstrate that, although MTF-1 is highly modified in vivo, its phosphorylation level does not rapidly change in response to metals, nor does its overall modification pattern. Recombinant MTF-1 was found to serve as an in vitro substrate for casein kinase II, c-Jun N-terminal kinase and protein kinase C, but inhibition of these kinases in vivo did not significantly change the modification pattern of MTF-1. Northern blotting revealed that inhibitors of casein kinase II and c-Jun N-terminal kinase severely attenuate the metal-induced transcription of the native chromatin-packaged metallothionein-1 and zinc transporter-1 genes, whereas protein kinase C inhibitors exerted gene- and cell-type-specific effects on the metal regulation and basal expression of these two genes. A chromatin immunoprecipitation assay was used to demonstrate that none of these inhibitors prevent the metal-dependent recruitment of MTF-1 to the MT-1 promoter. In brief, results of the present study suggest that protein kinases may not alter the phosphorylation state of MTF-1 during the rapid-response phase to metals, nor do they regulate the metal-dependent formation of a stable MTF-1-chromatin complex. Instead, protein kinases may exert their interdependent effects on metal-induced gene expression by acting on cofactors that interact with MTF-1.

Original languageEnglish (US)
Pages (from-to)33-41
Number of pages9
JournalBiochemical Journal
Volume382
Issue number1
DOIs
Publication statusPublished - Aug 15 2004

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Keywords

  • Metal
  • Metal-response-element-binding transcription factor-1 (MTF-1)
  • Metallothionein
  • Phosphorylation
  • Signal transduction
  • Zinc transporter-1

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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