PMID:23624625

Citation	Case, AJ, Li, S, Basu, U, Tian, J and Zimmerman, MC (2013) Mitochondrial-localized NADPH oxidase 4 is a source of superoxide in angiotensin II-stimulated neurons. Am. J. Physiol. Heart Circ. Physiol. 305:H19-28
Abstract	Angiotensin II (ANG II) plays an important role in the central regulation of systemic cardiovascular function. ANG II-mediated intraneuronal signaling has been shown to be predicated by an increase in mitochondrial superoxide (O₂∙-), yet the source of this reactive oxygen species (ROS) production remains unclear. NADPH oxidase 4 (Nox4), a member of the NADPH oxidase family, has been reported to be localized in mitochondria of various cell types and has been implicated in brain angiotensinergic signaling. However, the subcellular localization and function of Nox4 in neurons has not been fully elucidated. In this study, we hypothesized that Nox4 is expressed in neuron mitochondria and is involved in ANG II-dependent O₂∙--mediated intraneuronal signaling. To query this, Nox4 immunofluorescent staining and mitochondrial enrichment were performed in a mouse catecholaminergic neuronal cell model (CATH.a). Nox4 was shown to be present in neuron mitochondria as evidenced by colocalization with both the mitochondrial-localized protein manganese superoxide dismutase (MnSOD) and dye MitoTracker Red. Moreover, Nox4 expression was significantly increased in enriched mitochondrial fractions compared with whole cell lysates. Additionally, adenoviral-encoded small interfering RNA for Nox4 (AdsiNox4) caused a robust knockdown in Nox4 mRNA and protein levels, which led to the attenuation of ANG II-induced mitochondrial O₂∙- production. Finally, in the subfornical organ (SFO) of the brain, Nox4 not only demonstrated mitochondrial localization but was induced by chronic, peripheral infusion of ANG II. Collectively, these data suggest that Nox4 is a source of O₂∙- in neuron mitochondria that contributes to ANG II intraneuronal signaling.
Links	PubMed PMC3727106 Online version:10.1152/ajpheart.00974.2012
Keywords	Angiotensin II/pharmacology; Animals; Cell Line; Gene Expression; Mice; Mice, Inbred C57BL; Mitochondria/enzymology; Mitochondria/metabolism; NADPH Oxidase/genetics; NADPH Oxidase/metabolism; Neurons/drug effects; Neurons/enzymology; Neurons/metabolism; RNA, Small Interfering; Signal Transduction; Superoxide Dismutase/metabolism; Superoxides/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
MOUSE:NOX4		GO:0005739: mitochondrion	ECO:0000314:		C		Fig.1 shows immunofluorescence reveals Nox4 localized to neuron mitochondria. Fig.2 shows Nox4 expression is increased in neuron mitochondria-enriched cellular fraction	complete CACAO 11841
MOUSE:NOX4		GO:0043025: neuronal cell body	ECO:0000314:		C		Fig.5 shows Nox4 silencing attenuates ANG II-induced increase in intracellular superoxide levels. Fig.6 shows Nox4 knockdown inhibits ANG II-induced increase in mitochondrial superoxide levels.	complete CACAO 11843

References

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