title: Identification of the hypoxia-inducible factor 2α nuclear interactome in melanoma cells reveals master proteins involved in melanoma development.
abstract: Hypoxia-inducible factors (HIFs) are heterodimeric transcription factors that play a key role in cellular adaptation to hypoxia. HIF proteins are composed of an α subunit regulated by oxygen pressure (essentially HIF1α or HIF2α) and a constitutively expressed β subunit. These proteins are often overexpressed in cancer cells, and HIF overexpression frequently correlates with poor prognosis, making HIF proteins promising therapeutic targets. HIF proteins are involved in melanoma initiation and progression; however, the specific function of HIF2 in melanoma has not yet been studied comprehensively. Identifying protein complexes is a valuable way to uncover protein function, and affinity purification coupled with mass spectrometry and label-free quantification is a reliable method for this approach. We therefore applied quantitative interaction proteomics to identify exhaustively the nuclear complexes containing HIF2α in a human melanoma cell line, 501mel. We report, for the first time, a high-throughput analysis of the interactome of an HIF subunit. Seventy proteins were identified that interact with HIF2α, including some well-known HIF partners and some new interactors. The new HIF2α partners microphthalmia-associated transcription factor, SOX10, and AP2α, which are master actors of melanoma development, were confirmed via co-immunoprecipitation experiments. Their ability to bind to HIF1α was also tested: microphthalmia-associated transcription factor and SOX10 were confirmed as HIF1α partners, but the transcription factor AP2α was not. AP2α expression correlates with low invasive capacities. Interestingly, we demonstrated that when HIF2α was overexpressed, only cells expressing large amounts of AP2α exhibited decreased invasive capacities in hypoxia relative to normoxia. The simultaneous presence of both transcription factors therefore reduces cells' invasive properties. Knowledge of the HIF2α interactome is thus a useful resource for investigating the general mechanisms of HIF function and regulation, and here we reveal unexpected, distinct roles for the HIF1 and HIF2 isoforms in melanoma progression.
authors.affiliation: Université de Toulouse, UPS, IPBS, Toulouse, France.
authors.forename: Anne-Lise
authors.initials: AL
authors.lastname: Steunou
authors.forename: Manuelle
authors.initials: M
authors.lastname: Ducoux-Petit
authors.forename: Ikrame
authors.initials: I
authors.lastname: Lazar
authors.forename: Bernard
authors.initials: B
authors.lastname: Monsarrat
authors.forename: Monique
authors.initials: M
authors.lastname: Erard
authors.forename: Catherine
authors.initials: C
authors.lastname: Muller
authors.forename: Eric
authors.initials: E
authors.lastname: Clottes
authors.forename: Odile
authors.initials: O
authors.lastname: Burlet-Schiltz
authors.forename: Laurence
authors.initials: L
authors.lastname: Nieto
mesh_terms: D000595:Amino Acid Sequence; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D002465:Cell Movement; D002467:Cell Nucleus / Q000378:metabolism*; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D047468:Immunoprecipitation; D013058:Mass Spectrometry / Q000379:methods; D008545:Melanoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D051739:Microphthalmia-Associated Transcription Factor / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D011485:Protein Binding; D025941:Protein Interaction Mapping / Q000379:methods; D020543:Proteome / Q000235:genetics / Q000378:metabolism*; D040901:Proteomics / Q000379:methods*; D034622:RNA Interference; D055757:SOXE Transcription Factors / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D050656:Transcription Factor AP-2 / Q000235:genetics / Q000378:metabolism; D000099162:Endothelial PAS Domain-Containing Protein 1
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D051739:Microphthalmia-Associated Transcription Factor; D020543:Proteome; D055757:SOXE Transcription Factors; D050656:Transcription Factor AP-2; D000099162:Endothelial PAS Domain-Containing Protein 1; C497442:HIF1A protein, human; C497234:MITF protein, human; C527923:SOX10 protein, human; C493673:TFAP2A protein, human