Phosphorylation of HSF1 by MAPK-activated protein kinase 2 on serine 121, inhibits transcriptional activity and promotes HSP90 binding

J Biol Chem. 2006 Jan 13;281(2):782-91. doi: 10.1074/jbc.M505822200. Epub 2005 Nov 8.


Heat shock transcription factor 1 (HSF1) monitors the structural integrity of intracellular proteins and its regulation is essential for the health and longevity of eukaryotic organisms. HSF1 also plays a role in the acute inflammatory response in the negative regulation of cytokine gene transcription. Here we show, for the first time, that HSF1 is regulated by the proinflammatory protein kinase MAPKAP kinase 2 (MK2). We have shown that MK2 directly phosphorylates HSF1 and inhibits activity by decreasing its ability to bind the heat shock elements (HSE) found in the promoters of target genes encoding the HSP molecular chaperones and cytokine genes. We show that activation of HSF1 to bind HSE in hsp promoters is inhibited through the phosphorylation of a specific residue, serine 121 by MK2. A potential mechanism for MK2-induced HSF1 inactivation is suggested by the findings that phosphorylation of serine 121 enhances HSF1 binding to HSP90, a major repressor of HSF1. Dephosphorylation of serine 121 in cells exposed to non-steroidal anti-inflammatory drugs leads to HSP90 dissociation from HSF1, which then forms active DNA binding trimers. These experiments indicate a novel mechanism for the regulation of HSF1 by proinflammatory signaling and may permit HSF1 to respond rapidly to extracellular events, permitting optimal physiological regulation.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Blotting, Western
  • Cell Line
  • Cell Nucleus / metabolism
  • Chromatography, Gel
  • DNA-Binding Proteins / metabolism*
  • Dimerization
  • HSP90 Heat-Shock Proteins / chemistry*
  • HSP90 Heat-Shock Proteins / metabolism
  • HeLa Cells
  • Heat Shock Transcription Factors
  • Humans
  • Immunoprecipitation
  • Inflammation
  • MAP Kinase Kinase 2 / chemistry
  • MAP Kinase Kinase 2 / metabolism*
  • Molecular Sequence Data
  • Mutation
  • Phosphorylation
  • Phosphoserine / chemistry
  • Plasmids / metabolism
  • Promoter Regions, Genetic
  • Protein Binding
  • Sequence Homology, Amino Acid
  • Serine / chemistry*
  • Signal Transduction
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  • Transcription Factors / metabolism*
  • Transcription, Genetic*
  • Transfection


  • DNA-Binding Proteins
  • HSF1 protein, human
  • HSP90 Heat-Shock Proteins
  • Heat Shock Transcription Factors
  • Transcription Factors
  • Phosphoserine
  • Serine
  • MAP Kinase Kinase 2