Abstract
Heat shock factor 1 (HSF1) regulates the transcription of molecular chaperone hsp genes. However, the cellular control mechanisms that regulate HSF1 activity are not well understood. In this study, we have demonstrated for the first time that human HSF1 binds to the essential cell signaling protein 14-3-3 epsilon. Binding of HSF1 to 14-3-3 epsilon occurs in cells in which extracellular signal regulated kinase (ERK) is activated and blockade of the ERK pathway by treatment with the specific ERK pathway inhibitor PD98059 in vivo strongly suppresses the binding. We previously showed that ERK1 phosphorylates HSF1 on serine 307 and leads to secondary phosphorylation by glycogen synthase kinase 3 (GSK3) on serine 303 within the regulatory domain and that these phosphorylation events repress HSF1. We show here that HSF1 binding to 14-3-3 epsilon requires HSF1 phosphorylation on serines 303 and 307. Furthermore, the serine phosphorylation-dependent binding of HSF1 to 14-3-3 epsilon results in the transcriptional repression of HSF1 and its sequestration in the cytoplasm. Leptomycin B, a specific inhibitor of nuclear export receptor CRM1, was found to reverse the cytoplasmic sequestration of HSF1 mediated by 14-3-3 epsilon, suggesting that CRM1/14-3-3 epsilon directed nuclear export plays a major role in repression of HSF1 by the ERK/GSK3/14-3-3 epsilon pathway. Our experiments indicate a novel pathway for HSF1 regulation and suggest a mechanism for suppression of its activity during cellular proliferation.
Publication types
-
Research Support, U.S. Gov't, P.H.S.
MeSH terms
-
14-3-3 Proteins
-
Amino Acid Sequence
-
Cytoplasm / metabolism*
-
DNA-Binding Proteins / genetics
-
DNA-Binding Proteins / metabolism*
-
Enzyme Inhibitors / pharmacology
-
Exportin 1 Protein
-
Fatty Acids, Unsaturated / pharmacology
-
Flavonoids / pharmacology
-
Gene Expression Regulation
-
HeLa Cells / drug effects
-
Heat Shock Transcription Factors
-
Humans
-
Karyopherins / antagonists & inhibitors
-
Karyopherins / metabolism
-
MAP Kinase Kinase 1
-
Mitogen-Activated Protein Kinase Kinases / antagonists & inhibitors
-
Mitogen-Activated Protein Kinase Kinases / metabolism
-
Mitogen-Activated Protein Kinases / metabolism
-
Molecular Chaperones / genetics*
-
Molecular Chaperones / metabolism
-
Molecular Sequence Data
-
Phosphorylation
-
Protein Binding
-
Protein Serine-Threonine Kinases / antagonists & inhibitors
-
Protein Serine-Threonine Kinases / metabolism
-
Receptors, Cytoplasmic and Nuclear*
-
Recombinant Proteins / genetics
-
Recombinant Proteins / metabolism
-
Serine / metabolism*
-
Transcription Factors
-
Transcription, Genetic*
-
Tyrosine 3-Monooxygenase / genetics
-
Tyrosine 3-Monooxygenase / metabolism*
Substances
-
14-3-3 Proteins
-
DNA-Binding Proteins
-
Enzyme Inhibitors
-
Fatty Acids, Unsaturated
-
Flavonoids
-
HSF1 protein, human
-
Heat Shock Transcription Factors
-
Karyopherins
-
Molecular Chaperones
-
Receptors, Cytoplasmic and Nuclear
-
Recombinant Proteins
-
Transcription Factors
-
Serine
-
Tyrosine 3-Monooxygenase
-
Protein Serine-Threonine Kinases
-
Mitogen-Activated Protein Kinases
-
MAP Kinase Kinase 1
-
MAP2K1 protein, human
-
Mitogen-Activated Protein Kinase Kinases
-
2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one
-
leptomycin B