The Werner syndrome gene product (WRN): a repressor of hypoxia-inducible factor-1 activity.
Werner syndrome (WS) is a rare autosomal disease characterized by the premature onset of several age-associated pathologies. The protein defective in WS patients (WRN) is a helicase/exonuclease involved in DNA repair, replication, transcription and telomere maintenance. Hypoxia-inducible factor-1 (HIF-1) is a decisive element for the transcriptional regulation of genes essential for adaptation to low oxygen conditions. HIF-1 is also implicated in the molecular mechanisms of ageing. Here, we show that the cellular depletion of WRN protein (by siRNA targeting) leads to increased HIF-1 complex stabilization and activation. HIF-1 activation in the absence of WRN involves the generation of mitochondrial reactive oxygen species (mtROS) since SkQ1, a mitochondrial-targeted antioxidant, and stigmatellin, an inhibitor of mitochondrial complex III, blocked increased HIF-1 levels. Ascorbate, an essential co-factor involved in HIF-1 stability, was decreased in WRN-depleted cells. Interestingly, expression levels of GLUT1, a known dehydroascorbic acid transporter, were also decreased in WRN-depleted cells. Ascorbate supplementation of WRN-depleted cells led to a dose-dependent inhibition of HIF-1 activation. These results indicate that WRN protein regulates HIF-1 activation by affecting mitochondrial ROS production and intracellular ascorbate levels. This work provides a novel mechanistic link between HIF-1 activity and different age-associated pathologies.
Centre de Recherche en Cancérologie de l'Université Laval, Centre de recherche du CHUQ, L'Hôtel-Dieu de Québec, Québec, QC, Canada G1R 2J6.
Adam
A
Labbé
Véronique N
VN
Lafleur
David A
DA
Patten
Geneviève A
GA
Robitaille
Chantal
C
Garand
Laurent
L
Lamalice
Michel
M
Lebel
Darren E
DE
Richard
D002478:Cells, Cultured; D005090:Exodeoxyribonucleases / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins; D009363:Neoplasm Proteins / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D053484:RecQ Helicases / Q000235:genetics / Q000378:metabolism*; D014898:Werner Syndrome / Q000235:genetics*; D000071657:Werner Syndrome Helicase
C405619:HIGD1A protein, human; D047908:Intracellular Signaling Peptides and Proteins; D024101:Mitochondrial Proteins; D009363:Neoplasm Proteins; D017382:Reactive Oxygen Species; D005090:Exodeoxyribonucleases; D053484:RecQ Helicases; C098785:WRN protein, human; D000071657:Werner Syndrome Helicase