title: Identification of a novel partner of duox: EFP1, a thioredoxin-related protein.
abstract: H(2)O(2) is a crucial substrate of thyroproxidase (TPO) to iodinate thyroglobulin and synthesize thyroid hormones in thyroid. ThOX proteins (thyroid oxidase) also called Duox are believed to be responsible for H(2)O(2) generation. Duoxs expressed in transfected cells do not generate an active system, nor permit their membrane localization suggesting that other proteins are required to fulfill these functions. In this study, we demonstrate interactions of Duoxs with TPO and with p22(phox) without any effect on Duox activity. By yeast two-hybrid method using EF-hand fragment of dog Duox1 as the bait we have isolated EFP1 (EF-hand binding protein 1), one partner of Duoxs that belongs to the thioredoxin-related protein family. EFP1 shares moderate similarities with other members of thioredoxin-related proteins, but the characteristic active site and the folding structures are well conserved. EFP1 can be co-immunoprecipitated with Duoxs in transfected COS cells as well as in primary cultured human thyrocytes. It interacts also with TPO but not thyroglobulin. Immunofluorescence studies show that EFP1 and Duox proteins are co-localized inside the transfected cells, suggesting that EFP1 is not sufficient to induce either the expression of Duox at the plasma membrane or to permit H(2)O(2) production. EFP1 and Duox mRNA share similar distribution in nine different tissues. These results suggest that EFP1 could be one of the partners in the assembly of the multiprotein complex constituting the thyroid H(2)O(2) generating system but is certainly not sufficient to permit H(2)O(2) generation.
authors.affiliation: Institut de Recherche Interdisciplinaire, Université Libre De Bruxelles, Campus Erasme, 808, route de Lennik, 1070 Bruxelles, Belgium.
authors.forename: Dantong
authors.initials: D
authors.lastname: Wang
authors.forename: Xavier
authors.initials: X
authors.lastname: De Deken
authors.forename: Milutin
authors.initials: M
authors.lastname: Milenkovic
authors.forename: Yue
authors.initials: Y
authors.lastname: Song
authors.forename: Isabelle
authors.initials: I
authors.lastname: Pirson
authors.forename: Jacques E
authors.initials: JE
authors.lastname: Dumont
authors.forename: Françoise
authors.initials: F
authors.lastname: Miot
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D015152:Blotting, Northern; D016466:CHO Cells; D019556:COS Cells; D017173:Caenorhabditis elegans; D002352:Carrier Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000502:physiology*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003001:Cloning, Molecular; D006224:Cricetinae; D018076:DNA, Complementary / Q000378:metabolism; D004330:Drosophila; D000074623:Dual Oxidases; D020224:Expressed Sequence Tags; D005420:Flavoproteins / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D047468:Immunoprecipitation; D026901:Membrane Transport Proteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009252:NADPH Dehydrogenase / Q000378:metabolism; D019255:NADPH Oxidases / Q000737:chemistry* / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D011485:Protein Binding; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013879:Thioredoxins / Q000737:chemistry*; D013961:Thyroid Gland / Q000166:cytology; D014018:Tissue Distribution; D014162:Transfection; D020798:Two-Hybrid System Techniques
chemical_list: D002352:Carrier Proteins; D018076:DNA, Complementary; D005420:Flavoproteins; D026901:Membrane Transport Proteins; D010750:Phosphoproteins; D012333:RNA, Messenger; C497165:TXNDC11 protein, human; D013879:Thioredoxins; D006861:Hydrogen Peroxide; D000074623:Dual Oxidases; D019255:NADPH Oxidases; C086986:CYBA protein, human; C431513:DUOX1 protein, human; D009252:NADPH Dehydrogenase