Dual oxidase-2 has an intrinsic Ca2+-dependent H 2O2-generating activity

Rabii Ameziane-El-Hassani, Stanislas Morand, Jean Luc Boucher, Yves Michel Frapart, Daphné Apostolou, Diane Agnandji, Sédami Gnidehou, Renée Ohayon, Marie Sophie Noël-Hudson, Jacques Francon, Khalid Lalaoui, Alain Virion, Corinne Dupuy

    Résultats de recherche: Contribution à un journalArticleRevue par des pairs

    197 Citations (Scopus)

    Résumé

    Duox2 (and probably Duox1) is a glycoflavoprotein involved in thyroid hormone biosynthesis, as the thyroid H2O2 generator functionally associated with Tpo (thyroperoxidase). So far, because of the impairment of maturation and of the targeting process, transfecting DUOX into nonthyroid cell lines has not led to the expression of a functional H 2O2-generating system at the plasma membrane. For the first time, we investigated the H2O2-generating activity in the participate fractions from DUOX2- and DUOX1-transfected HEK293 and Chinese hamster ovary cells. The particulate fractions of these cells stably or transiently transfected with human or porcine DUOX cDNA demonstrate a functional NADPH/Ca2+-dependent H2O2-generating activity. The immature Duox proteins had less activity than pig thyrocyte particulate fractions, and their activity depended on their primary structures. Human Duox2 seemed to be more active than human Duox1 but only half as active as its porcine counterpart. TPO co-transfection produced a slight increase in the enzymatic activity, whereas p22phox, the 22-kDa subunit of the leukocyte NADPH oxidase, had no effect. In previous studies on the mechanism of H 2O2 formation, it was shown that mature thyroid NADPH oxidase does not release O2 .- but H2O 2. Using a spin-trapping technique combined with electron paramagnetic resonance spectroscopy, we confirmed this result but also demonstrated that the partially glycosylated form of Duox2, located in the endoplasmic reticulum, generates superoxide in a calcium-dependent manner. These results suggest that post-translational modifications during the maturation process of Duox2 could be implicated in the mechanism of H2O 2 formation by favoring intramolecular superoxide dismutation.

    langue originaleAnglais
    Pages (de - à)30046-30054
    Nombre de pages9
    journalJournal of Biological Chemistry
    Volume280
    Numéro de publication34
    Les DOIs
    étatPublié - 26 août 2005

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