Nox2 contributes to age-related oxidative damage to neurons and the cerebral vasculature
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
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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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 6

Nox2 activity and activation of stress signaling pathways in WT and HuNox2Tg mouse midbrain tissues.

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Nox2 activity and activation of stress signaling pathways in WT and HuNo...
(A) ROS production detected by lucigenin chemiluminescence in the presence of SCP or Nox2tat. (B) O2•– production as detected by SOD-inhibitable cytochrome c reduction assay. (C) H2O2 production detected by catalase-inhibitable Amplex red assay. (D) Endothelial Nox2 expression. Endothelial cells were labeled with CD31 (red), and Nox2 was labeled with FITC. Yellow represents endothelial Nox2 expression. (E) ROS production as detected by DHE fluorescence on midbrain sections. (F) p47phox and MARCKS phosphorylation. ODs of protein bands were quantified and normalized to α-tubulin detected in the same sample. (G) Brain tissue Ang II levels as detected by ELISA. (H) Immunofluorescence detection of phospho-ERK1/2 (red, top row) and γH2AX (red, bottom row). Nuclei were labeled with DAPI (blue). Pink indicates the nuclear location of γH2AX. Scale bars: 100 μm. n = 6 mouse brains and 3 sections/per brain. *P < 0.05 for indicated values versus young values in the same genetic group; †P < 0.05 for indicated values versus WT values of the same age group; #P < 0.05 for indicated values versus values without inhibitor in the same age and genetic group. Statistical analysis was performed using 1-way ANOVA followed by Bonferroni’s post hoc tests.