Transcription factor GABP/NRF-2 controlling biogenesis of mitochondria regulates basal expression of peroxiredoxin V but the mitochondrial function of peroxiredoxin V is dispensable in the dog.
ABSTRACT Peroxiredoxins (PRDXs) represent a conserved family of six antioxidant proteins which are widely expressed in different organisms. Human PRDX5 is detected in the cytosol and nucleus and can also target peroxisomes and mitochondria. However, it remains unknown if mitochondrial localization of PRDX5 is essential for its functions. Here we studied whether the known regulator of mitochondrial biogenesis, transcription factor GABP/NRF-2, is required for the basal expression of the human PRDX5 gene and what the significance is of the mitochondrial targeting of the PRDX5 protein. It was found that mutation-mediated inactivation of all potential binding sites for GAPB in the PRDX5 promoter lead to ∼80% inhibition of its basal activity in a reporter gene assay. Co-transfection of plasmids expressing GABP-alpha and GABP-beta stimulated activity of the non-mutated PRDX5 promoter but had no effect on the mutated promoter, suggesting that basal expression of the human PRDX5 gene is regulated by GABP. We found that the dog c-Myc-tagged PRDX5 did not target the mitochondria of human cells. Endogenously expressed PRDX5 also showed no association with mitochondria in the dog cells. It appears, therefore, that during evolution the dog PRDX5 gene lost its upstream ATG codon and mitochondrial targeting signal without major functional consequences.
- SourceAvailable from: Bernard Knoops[show abstract] [hide abstract]
ABSTRACT: In human, the subcellular targeting of peroxiredoxin-5 (PRDX5), a thioredoxin peroxidase, is dependent on the use of multiple alternative transcription start sites and two alternative in-frame translation initiation sites, which determine whether or not the region encoding a mitochondrial targeting sequence (MTS) is translated. In the present study, the abolition of PRDX5 mitochondrial targeting in dog is highlighted and the molecular mechanism underlying the loss of mitochondrial PRDX5 during evolution is examined. Here, we show that the absence of mitochondrial PRDX5 is generalized among the extant canids and that the first events leading to PRDX5 MTS abolition in canids involve a mutation in the more 5' translation initiation codon as well as the appearance of a STOP codon. Furthermore, we found that PRDX5 MTS functionality is maintained in giant panda and northern elephant seal, which are phylogenetically closely related to canids. Also, the functional consequences of the restoration of mitochondrial PRDX5 in dog Madin-Darby canine kidney (MDCK) cells were investigated. The restoration of PRDX5 mitochondrial targeting in MDCK cells, instead of protecting, provokes deleterious effects following peroxide exposure independently of its peroxidase activity, indicating that mitochondrial PRDX5 gains cytotoxic properties under acute oxidative stress in MDCK cells. Altogether our results show that, although mitochondrial PRDX5 cytoprotective function against oxidative stress has been clearly demonstrated in human and rodents, PRDX5 targeting to mitochondria has been evolutionary lost in canids. Moreover, restoration of mitochondrial PRDX5 in dog MDCK cells, instead of conferring protection against peroxide exposure, makes them more vulnerable.PLoS ONE 01/2013; 8(9):e72844. · 3.73 Impact Factor
- 11/2011; , ISBN: 978-953-307-714-7
Conference Proceeding: 3-dimensional configuration to promote timely settling of quantum-dot cellular automata[show abstract] [hide abstract]
ABSTRACT: Asymmetric spacing is a previously proposed design methodology for removing the possibility of metastable states in Quantum-dot Cellular Automata (QCA). A new three-dimensional architecture is presented which should yield the same effect. Both the asymmetric method and the 3D architecture are compared and contrasted. Simulations on the propagation of a signal down a binary wire indicate that this new architecture is an effective way to remove the meta-stable states.Nanotechnology, 2003. IEEE-NANO 2003. 2003 Third IEEE Conference on; 09/2003