title: Molecular cloning and characterization of the Xenopus hypoxia-inducible factor 1alpha (xHIF1alpha).
abstract: We report the molecular cloning and the characterization of the Xenopus homolog of mammalian hypoxia-inducible factor 1alpha (HIF1alpha), a member of the bHLH/PAS transcription factor family. Searches in Xenopus genome sequences and phylogenetic analysis reveal the existence of HIF1alpha and HIF2alpha paralogs in the Xenopus laevis species. Sequence data analyses indicate that the organization of protein domains in Xenopus HIF1alpha (xHIF1alpha) is strongly conserved. We also show that xHIF1alpha heterodimerizes with the Xenopus Arnt1 protein (xArnt1) with the proteic complex being mediated by the HLH and PAS domains. Subcellular analysis in a Xenopus XTC cell line using chimeric GFP constructs show that over-expression of xHIF1alpha and xArnt1 allows us to detect the xHIF1alpha/xArnt1 complex in the nucleus, but only in the presence of both partners. Further analyses in XTC cell line show that over-producing xHIF1alpha and xArnt1 mediates trans-activation of the hypoxia response element (HRE) reporter. The trans-activation level can be increased in hypoxia conditions. Interestingly such trans-activation properties can be also observed when human Arnt1 is used together with the xHIF1alpha.
authors.affiliation: Université Pierre et Marie Curie, UMR7622-CNRS Biologie Moléculaire et Cellulaire du Développement, 9 quai St. Bernard, 75252 Paris Cedex 05, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: de Beaucourt
authors.forename: Pascal
authors.initials: P
authors.lastname: Coumailleau
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator / Q000378:metabolism; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D017124:Conserved Sequence; D017930:Genes, Reporter; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins / Q000378:metabolism; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics* / Q000378:metabolism; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D010802:Phylogeny; D010957:Plasmids; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D020218:Response Elements; D017386:Sequence Homology, Amino Acid; D013347:Subcellular Fractions / Q000378:metabolism; D015533:Transcriptional Activation; D014981:Xenopus / Q000235:genetics*; D029867:Xenopus Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: C527133:ARNT protein, Xenopus; C527134:HIF1A protein, Xenopus; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D029867:Xenopus Proteins; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D049452:Green Fluorescent Proteins