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Redox properties of mitochondria from C57BL/6J mice that lack NADP+‐transhydrogenase activity due to spontaneous NNT mutation
Author(s) -
Figueira Tiago Rezende,
Ronchi Juliana Aparecida,
Ravagnani Felipe Gustavo,
Oliveira Helena Coutinho,
Vercesi Anibal Eugenio,
Castilho Roger Frigerio
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.lb56
Subject(s) - nad+ kinase , mitochondrion , biochemistry , chemistry , ubiquinol , glutathione , glycerol 3 phosphate dehydrogenase , nicotinamide , redox , mitochondrial matrix , reactive oxygen species , microbiology and biotechnology , biology , enzyme , cytosol , coenzyme q – cytochrome c reductase , cytochrome c , organic chemistry
NADPH homeostasis is critical for mitochondrial H2O2 detoxification. Nicotinamide nucleotide transhydrogenase (NNT) is located in the inner mitochondrial membrane and contributes to an elevated NADPH/NADP+ ratio. This enzyme catalyzes the reduction of NADP+ at the expense of NADH and H+ reentry to the matrix. A spontaneous NNT mutation in C57BL/6J mice arose nearly 3 decades ago but was only discovered in 2005. We aimed to study redox functions of mitochondria from C57BL/6J mice. Liver mitochondria were isolated from both an NNT wild‐type C57BL/6 substrain (C57BL/6/JUnib) and from C57BL/6J mice. Refined NAD(P)H autofluorescence evaluations in respiring mitochondria revealed abnormalities in C57BL/6J mice, including an absence of transhydrogenation between NAD and NADP, the spontaneous oxidation of NADPH, and the very poor ability to metabolize organic peroxide (t‐BOOH). In addition, the mitochondria of C57BL/6J mice displayed a higher ratio of oxidized:reduced glutathione as compared to C57BL/6/JUnib wild‐type mice. The activity of mitochondrial IDH2 (a coexisting source of NADPH) was similar between both groups. Overall, our findings indicate that NNT loss due to mutation greatly affects mitochondrial NAD(P) redox homeostasis, especially upon peroxide challenge. Given these alterations, the potential scientific drawbacks of using C57BL/6J mice in biomedical research should not be overlooked.