Research activities

RESEARCH ACTIVITIES

ANIMAL PEROXIREDOXINS AND THIOREDOXIN SYSTEMS

In 1997, during a research project leaded by Prof. Alfred Bernard and aimed at identifying new lung proteins, we have cloned human, rat and mouse cDNAs encoding a novel mammalian antioxidant enzyme of the peroxiredoxin family. This enzyme was first named AOEB166 for antioxidant enzyme B166. The deduced amino acid sequence revealed that AOEB166 was a new mammalian member of the peroxiredoxin family. AOEB166 is now designated as peroxiredoxin 5. Peroxiredoxins are recently discovered enzymes that play essential roles in bacteria, archaea and eukaryotes in reducing hydrogen peroxide, organic hydroperoxides and peroxynitrite by the use of reducing equivalents derived from thiol-containing donor molecules such as thioredoxin.

In our initial report, we showed that peroxiredoxin 5 is indeed a peroxidase. The analysis of peroxiredoxin 5 mRNA distribution in 30 different human tissues showed also that the gene is widely expressed in the body. Of interest, the analysis of N- and C-terminal domains of peroxiredoxin 5 revealed amino acid sequences presenting features of mitochondrial and peroxisomal targeting sequences. Furthermore, human peroxiredoxin 5 expressed as a fusion protein with GFP in HepG2 cell line was sorted to these organelles.

Since our initial characterization of human peroxiredoxin 5, we have studied, in collaboration with different groups, the expression and the regulation of this antioxidant enzyme in inflammatory-associated diseases such as osteoarthritis. Moreover, antioxidant protection conferred by mitochondrial human peroxiredoxin 5 was studied using Saccharomyces cerevisiae or human cell lines overexpressing the enzyme.

More recently, it was shown that recombinant peroxiredoxin 5 applied exogenously is able to protect against excitotoxic brain lesions in newborn mice. Cloning peroxiredoxin 5 in bovine, pig, baboon, african green monkey and identification of homologues in Branchiostoma and Drosophila revealed also the very high conservation of the enzyme and its conserved mitochondrial subcellular localization during evolution. These data suggest an essential role for peroxiredoxin 5 in this organelle.

Finally, in a collaborative work with Prof. Jean-Paul Declercq from the Laboratory of Crystallography of our University, the crystal structure of human peroxiredoxin 5 was reported in its reduced form and more recently in its oxidized form.

   

Our current work is aimed at characterizing functionally and structurally mitochondrial peroxiredoxin 5 and associated thioredoxin systems. Recent data obtained in our laboratory show that peroxiredoxin 5 is targeted to mitochondria in mammalian cells with high metabolic rate such as neurons of the central nervous system. A systematic study of peroxiredoxin 5 localization in rat tissues is performed using histological techniques. Moreover, we have engineered by transfection different mammalian cell lines that overexpress mitochondrial and cytosolic peroxiredoxin 5 or in which endogenous expression of peroxiredoxin 5 has been inactivated by siRNAs. These mammalian cell lines are now used to determine the cytoprotective activity of mitochondrial peroxiredoxin 5 against mitochondrial oxidative or nitro-oxidative stresses caused, for example, by paraquat, and by NO and ONOO- donors. Moreover, post-translational modifications of peroxiredoxin 5 are also studied such as phosphorylation. Indeed, it has been previously shown that enzymatic activity of other members of the mammalian peroxiredoxin family are highly regulated by phosphorylation of key residues.

     

Key publications: 

• KNOOPS B., GOEMAERE J., VAN DER EECKEN V., DECLERCQ J.P. Peroxiredoxin 5: Structure, mechanism and function of the mammalian atypical 2-Cys peroxiredoxin. Antioxidants & Redox Signaling, 15, 2011, 817-829
• DE SIMONI S., GOEMAERE J., KNOOPS B. Silencing of peroxiredoxin 3 and peroxiredoxin 5 reveals the role of mitochondrial peroxiredoxins in the protection of human SH-SY5Y cells toward MPP+. Neuroscience Letters, 433, 2008, 219-224
• TRUJILLO M., CLIPPE A., MANTA B., FERRER-SUETA G., SMEETS A., DECLERCQ J.P., KNOOPS B. & RADI R.. Pre-steady state kinetic characterization of human peroxiredoxin 5: taking advantage of Trp 84 fluorescence increase upon oxidation. Archives of Biochemistry and Biophysics, 467, 2007, 95-106
• NGUYEN-NHU N, BERCK J, CLIPPE A, DUCONSEILLE E, CHERIF H, BOONE C, VAN DER EECKEN V, BERNARD A, BANMEYER I, KNOOPS B, Human peroxiredoxin 5 gene organization, initial characterization of its promoter and identification of alternative forms of mRNA., Biochimica et Biophysica Acta, 1769, 2007, 472-483.
• BANMEYER I, MARCHAND C, CLIPPE A, KNOOPS B, Human mitochondrial peroxiredoxin 5 protects from mitochondrial DNA damages induced by hydrogen peroxide, FEBS Letters, 579, 2005, 2327-2333.
• DECLERCQ J-P, EVRARD C, CLIPPE A, VANDER STRICHT D, BERNARD A, KNOOPS B, Crystal structure of human peroxiredoxin 5, a novel type of mammalian peroxiredoxin at 1.54 Å resolution, Journal of Molecular Biology, 311, 2001, 751-759.
• KNOOPS B, CLIPPE A, BOGARD C, ARSALANE K, WATTIEZ R, HERMANS C, DUCONSEILLE E, FALMAGNE P, BERNARD A, Cloning and characterization of AOEB166, a novel mammalian antioxidant enzyme of the peroxiredoxin family, J Biol Chem, 274, 43, 1999, 30451-30458.