Hypoxia-induced activation of HIF-1: role of HIF-1alpha-Hsp90 interaction.
The protein chaperone heat shock protein 90 (Hsp90) is a major regulator of different transcription factors such as MyoD, a basic helix loop helix (bHLH) protein, and the bHLH-Per-aryl hydrocarbon nuclear translocator (ARNT)-Sim (PAS) factors Sim and aryl hydrocarbon receptor (Ahr). The transcription factor hypoxia-inducible factor-1alpha (HIF-1alpha), involved in the response to hypoxia, also belongs to the bHLH-PAS family. This work was aimed to investigate the putative role of Hsp90 in HIF-1 activation by hypoxia. Using a EGFP-HIF-1alpha fusion protein, co-immunoprecipitation experiments evidenced that the chimeric protein expressed in COS-7 cells interacts with Hsp90 in normoxia but not in hypoxia. We also demonstrated that Hsp90 interacts with the bHLH-PAS domain of HIF-1alpha. Moreover, Hsp90 is not co-translocated with HIF-1alpha into the nucleus. At last, we showed that Hsp90 activity is essential for HIF-1 activation in hypoxia since it is inhibited in the presence of geldanamycin. These results indicate that Hsp90 is a major regulator in HIF-1alpha activation.
Minet
E
E
Laboratoire de Biochimie et Biologie Cellulaire, Facultés Universitaires de la Paix, 61 rue de Bruxelles, 5000, Namur, Belgium. emmanuel.minet@fundp.ac.be
Mottet
D
D
Michel
G
G
Roland
I
I
Raes
M
M
Remacle
J
J
Michiels
C
C
D000818:Animals; D019556:COS Cells; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004730:Endothelium, Vascular; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D000860:Hypoxia / Q000378:metabolism*; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008856:Microscopy, Fluorescence; D018832:Molecular Chaperones; D009687:Nuclear Proteins / Q000378:metabolism*; D011485:Protein Binding; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection
D004268:DNA-Binding Proteins; C497442:HIF1A protein, human; D018841:HSP90 Heat-Shock Proteins; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D018832:Molecular Chaperones; D009687:Nuclear Proteins; D014157:Transcription Factors