Fig 2: Oxidative homeostasis. A: protein levels of oxidative and nitrosative enzymes. eNOS, endothelial nitric oxide synthase; iNOS, inducible nitric oxide synthase; XO, xanthine oxidase; NOX4, NADPH oxidase 4. B: protein levels of antioxidant enzymes. MnSOD, manganese superoxide dismutase; GPx1, glutathione peroxidase-1; GR, glutathione reductase; CuZnSOD, copper/zinc superoxide dismutase; HO1, heme oxygenase-1. C: mitochondrial complex activities. D: protein levels of mitochondrial enzymes. COX4, cytochrome-c oxidase complex IV; Cyt c, cytochrome c; glutamate DH, glutamate dehydrogenase. Data are presented as means ± SE for control (white bar) and Mat-Ob (gray bar) offspring. n = 6–8 per group. *P < 0.05, **P < 0.01, ***P < 0.001.

Fig 3: (a–c) Immunohistochemistry for nitrotyrosine (brown color) in YWT, OWT, and OTG, with quantification of staining density (d). (e) Levels of F2 isoprostanes, a marker of lipid oxidative damage, in kidney lysates (ng/g tissue). (f) Ratios of reduced glutathione to oxidized glutathione (GSH/GSSG) in kidney lysates. Nitrotyrosine and F2 isoprostanes were significantly increased in old mice, and GPX1 overexpression significantly decreased (nitrotyrosine) or tended to reduce (F2 isoprostanes) the increases observed in old mice. In contrast, the GSH/GSSG ratio tended to decrease in old mice, and GPX1 overexpression tended to rescue the decrease. N = 4–6. (g–i) Representative electron micrographs of mitochondria isolated from kidney cortex of YWT, OWT, and OTG. Scale bar: 0.5 µm. (j). Quantification of mitochondrial cristae density (number of cristae/µm). N = 3

Fig 4: Label-free shotgun proteomics of glomeruli from YWT, OWT, and OTG mice (n = 4 per group) (a–c). (a) Glomeruli were collected using laser capture microdissection, processed for proteomics (Orbitrap Lumos), and analyzed using Student's t tests (with corrections) for OWT versus YWT (aging effect) and OTG versus OWT (transgenic effect). (b, c) Heatmaps show comparisons of protein abundance of OWT versus YWT and OTG versus OWT, respectively. Red indicates increases, and blue indicates decreases, of abundance. Proteins were ranked according to fold-change with age for 77 proteins (see Table S1 for details), N = 4. (d) Targeted proteomics of tubules from YWT, OWT and OTG, which was focused on 139 selected proteins involved in glycolysis, Krebs cycle, mitochondrial respiratory complexes, fatty acid oxidation & biosynthesis, peroxisomes, antioxidants, and proteostasis (see Table S2 for details). In each heatmap, top row indicates OWT versus YWT (aging effect) and bottom row indicates OTG versus OWT (effect of GPX1 overexpression). *Substantial decrease in key enzymes of fatty acid oxidation with aging

Fig 5: SOD and GPX protein expression and activity in the STG of AD cases and controls. Sample supernatants displaying (A) Quantification of SOD1, SOD2 and GPX1 protein expression by direct (B) Total SOD activity, reflected by the inhibition of pyrogallol auto-oxidation as a % of a control lacking the presence of SOD, and (C) Total GPX activity, assessed by monitoring the consumption of NADPH. Data represent mean ± SD, n = 19 for control and n = 20 individual AD cases; *p < 0.05.