Heat shock protein hsp90 regulates dioxin receptor function in vivo

Murray L. Whitelaw, Jacqueline Mcguire, Didier Picard, Jan Åke Gustafsson, Lorenz Poellinger

Research output: Contribution to journalArticle

106 Scopus citations

Abstract

The dioxin (aryl hydrocarbon) receptor is a ligand-dependent basic helix- loop-helix (bHLH) factor that hinds to xenobiotic response elements of target promoters upon heterodimerization with the bHLH partner factor Arnt. Here we have replaced the bHLH motif of the dioxin receptor with a heterologous DNA- binding domain to create fusion proteins that mediate ligand-dependent transcriptional enhancement in yeast (Saccharomyces cerevisiae). Previously, our experiments indicated that the ligand-free dioxin receptor is stably associated with the 90-kDa heat shock protein, hsp90. To investigate the role of hsp90 in dioxin signaling we have studied receptor function in a yeast strain where hsp90 expression can be down-regulated to about 5% relative to wild-type levels. At low levels of hsp90, ligand-dependent activation of the chimeric dioxin receptor construct was almost completely inhibited, whereas the activity of a similar chimeric construct containing the structurally related Arnt factor was not affected. Moreover, a chimeric dioxin receptor construct lacking the central ligand- and hsp90-binding region of the receptor showed constitutive transcriptional activity in yeast that was not impaired upon down-regulation of hsp90 expression levels. Thus, these data suggest that hsp90 is a critical determinant of conditional regulation of dioxin receptor function in vivo via the ligand-binding domain.

Original languageEnglish (US)
Pages (from-to)4437-4441
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume92
Issue number10
DOIs
StatePublished - May 9 1995

Keywords

  • gene expression
  • protein folding
  • yeast

ASJC Scopus subject areas

  • General
  • Genetics

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