title: Hypoxia-enhanced expression of the proprotein convertase furin is mediated by hypoxia-inducible factor-1: impact on the bioactivation of proproteins.
abstract: Hypoxia is a common tumorigenesis enhancer, mostly owing to its impact on gene expression of many angiogenic and invasion-related mediators, some of which are natural substrates for the proprotein convertase furin. Analysis of furin promoters revealed the presence of putative binding sites for hypoxia-inducible factor-1 (HIF-1), a transcription complex that plays a pivotal role in cellular adaptation to hypoxia. In fact, we demonstrate herein that the levels of fur mRNA, encoding furin, are remarkably increased upon hypoxic challenge. Cotransfection of a HIF-1alpha dominant negative form in wild-type (WT) cells or transfection of a furin promoter-reporter gene in HIF-1-deficient cells indicated the requirement of HIF-1 for furin promoter activation by hypoxia. Direct HIF-1 action on the furin promoter was identified as a canonical hypoxia-responsive element site with enhancer capability. The hypoxic/HIF-1 regulation of furin correlated with an increased proteolytic activation of the substrates membrane-type 1 matrix metalloproteinase and transforming growth factor-beta1. Our findings unveil a new facet of the physiological consequences of hypoxia/HIF-1, through enhanced furin-induced proteolytic processing/activation of proproteins known to be involved in tumorigenesis.
authors.affiliation: Immunology Division, Pulmonary Division, Faculty of Medicine, Université de Sherbrooke, Sherbrooke, Québec.
authors.forename: Stephanie
authors.initials: S
authors.lastname: McMahon
authors.forename: Francine
authors.initials: F
authors.lastname: Grondin
authors.forename: Patrick P
authors.initials: PP
authors.lastname: McDonald
authors.forename: Darren E
authors.initials: DE
authors.lastname: Richard
authors.forename: Claire M
authors.initials: CM
authors.lastname: Dubois
mesh_terms: D001665:Binding Sites; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000502:physiology*; D045683:Furin / Q000235:genetics*; D005786:Gene Expression Regulation; D006801:Humans; D000860:Hypoxia / Q000235:genetics*; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D020781:Matrix Metalloproteinase 1 / Q000378:metabolism; D009363:Neoplasm Proteins / Q000378:metabolism; D009687:Nuclear Proteins / Q000502:physiology*; D011401:Promoter Regions, Genetic; D043484:Proprotein Convertases / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D015533:Transcriptional Activation; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000378:metabolism; D053773:Transforming Growth Factor beta1
chemical_list: D004268:DNA-Binding Proteins; C497442:HIF1A protein, human; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; C508960:TGFB1 protein, human; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D043484:Proprotein Convertases; D045683:Furin; D020781:Matrix Metalloproteinase 1