Nox2 contributes to age-related oxidative damage to neurons and the cerebral vasculature
Lampson M. Fan, … , Keith M. Channon, Jian-Mei Li
Lampson M. Fan, … , Keith M. Channon, Jian-Mei Li
Published July 22, 2019
Citation Information: J Clin Invest. 2019;129(8):3374-3386. https://doi.org/10.1172/JCI125173.
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Research Article Aging Neuroscience

Nox2 contributes to age-related oxidative damage to neurons and the cerebral vasculature

Abstract

Oxidative stress plays an important role in aging-related neurodegeneration. This study used littermates of WT and Nox2-knockout (Nox2KO) mice plus endothelial cell–specific human Nox2 overexpression–transgenic (HuNox2Tg) mice to investigate Nox2-derived ROS in brain aging. Compared with young WT mice (3–4 months), aging WT mice (20–22 months) had obvious metabolic disorders and loss of locomotor activity. Aging WT brains had high levels of angiotensin II (Ang II) and ROS production; activation of ERK1/2, p53, and γH2AX; and losses of capillaries and neurons. However, these abnormalities were markedly reduced in aging Nox2KO brains. HuNox2Tg brains at middle age (11–12 months) already had high levels of ROS production and activation of stress signaling pathways similar to those found in aging WT brains. The mechanism of Ang II–induced endothelial Nox2 activation in capillary damage was examined using primary brain microvascular endothelial cells. The clinical significance of Nox2-derived ROS in aging-related loss of cerebral capillaries and neurons was investigated using postmortem midbrain tissues of young (25–38 years) and elderly (61–85 years) adults. In conclusion, Nox2 activation is an important mechanism in aging-related cerebral capillary rarefaction and reduced brain function, with the possibility of a key role for endothelial cells.

Authors

Lampson M. Fan, Li Geng, Sarah Cahill-Smith, Fangfei Liu, Gillian Douglas, Chris-Anne Mckenzie, Colin Smith, Gavin Brooks, Keith M. Channon, Jian-Mei Li

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Figure 5

Nox2 expression, activation of stress signaling pathways, and oxidative damage in postmortem human midbrain tissues.

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Nox2 expression, activation of stress signaling pathways, and oxidative ...
(A) ROS production detected by lucigenin chemiluminescence in the presence of an SCP or Nox2tat. (B) ROS production by midbrain sections detected by DHE fluorescence with or without Peg-SOD. *P < 0.05 between indicated group values. (C) Brain tissue Ang II levels detected by ELISA. (D) Nox subunit and p53 expression and phosphorylation of ERK1/2 and H2AX (to form γH2AX) detected by Western blot analysis. (E) p47phox and MARCKS phosphorylation detected by Western blot analysis. ODs of protein bands were quantified and normalized to α-tubulin detected in the same samples. The phospho-ERK1/2 and γH2AX bands were normalized to the total protein bands detected in the same samples, expressed as OD P/T. (F) Immunofluorescence on midbrain sections. Nox2 was labeled with FITC; cerebral vessels were labeled with LE-lectin (FITC); neurons were labeled with NeuN (Cy3, red); and γH2AX was labeled by Cy3 (red). Nuclei were labeled with DAPI (blue) to visualize cells. Scale bars: 100 μm. n = 7–8 individual brains and 2 sections/per brain. Fluorescence intensities were quantified and expressed as percent relative to young (100%). *P < 0.05 for indicated values versus young values (C–F). Statistical analysis was performed using 1-way ANOVA followed by Bonferroni’s post hoc tests.