Heat and heavy metal stress synergize to mediate transcriptional hyperactivation by metal-responsive transcription factor MTF-1

J Biol Chem. 2003 Aug 22;278(34):31879-83. doi: 10.1074/jbc.M302138200. Epub 2003 Jun 12.

Abstract

Mammalian cells react to heavy metal stress by transcribing a number of genes that contain metal-response elements (MREs) in their promoter/enhancer region; this activation is mediated by metal-responsive transcription factor-1 (MTF-1). Well-known target genes of MTF-1 are those encoding metallothioneins, small, cysteine-rich proteins with a high affinity for heavy metals. The response to heat shock, another cell stress, is mediated by heat shock transcription factor 1 (HSF1), which activates a battery of heat shock genes. Little is known about the cross-talk between the different anti-stress systems of the cell. Here we report a synergistic activation of metal-responsive promoters by heavy metal load (zinc or cadmium) and heat shock. An obvious explanation, cooperativity between MTF-1 and HSF1, seems unlikely: transfected HSF1 boosts the activity of an Hsp70 promoter but hardly affects an MRE-containing promoter upon exposure to metal and heat shock. A clue to the mechanism is given by our finding that heat shock leads to intracellular accumulation of heavy metals. We propose that the known anti-apoptotic effect of heat shock proteins allows for cell survival despite heavy metal accumulation and, consequently, results in a hyperactivation of the metal response pathway.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • DNA-Binding Proteins
  • Hot Temperature*
  • Humans
  • Metals, Heavy / pharmacology*
  • Promoter Regions, Genetic
  • Protein Transport
  • Transcription Factor MTF-1
  • Transcription Factors / metabolism
  • Transcription Factors / physiology*
  • Transcription, Genetic* / drug effects

Substances

  • DNA-Binding Proteins
  • Metals, Heavy
  • Transcription Factors