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Dynamic optical imaging of metabolic and NADPH oxidase-derived superoxide in live mouse brain using fluorescence lifetime unmixing.

ABSTRACT: Superoxide is the single-electron reduction product of molecular oxygen generated by mitochondria and the innate immune enzyme complex, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox), and its isoforms. Initially identified as critical to the host defense against infection, superoxide has recently emerged as an important signaling molecule and as a proposed mediator of central nervous system injury in stroke, neurodegenerative conditions, and aging itself. Complete understanding of superoxide in central nervous system disease has been hampered by lack of noninvasive imaging techniques to evaluate this highly reactive, short-lived molecule in vivo. Here we describe a novel optical imaging technique to monitor superoxide real time in intact animals using a fluorescent probe compound and fluorescence lifetime contrast-based unmixing. Specificity for superoxide was confirmed using validated mouse models with enhanced or attenuated brain superoxide production. Application of fluorescence lifetime unmixing removed autofluorescence, further enhanced sensitivity and specificity of the technique, permitted visualization of physiologically relevant levels of superoxide, and allowed superoxide in specific brain regions (e.g., hippocampus) to be mapped. Lifetime contrast-based unmixing permitted disease model-specific and brain region-specific differences in superoxide levels to be observed, suggesting this approach may provide valuable information on the role of mitochondrial and Nox-derived superoxide in both normal function and pathologic conditions in the central nervous system.

SUBMITTER: Hall DJ

PROVIDER: S-EPMC3323297 | biostudies-literature | 2012 Jan

REPOSITORIES: biostudies-literature

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Dynamic optical imaging of metabolic and NADPH oxidase-derived superoxide in live mouse brain using fluorescence lifetime unmixing.

Hall David J DJ Han Sung-Ho SH Chepetan Andre A Inui Edny G EG Rogers Mike M Dugan Laura L LL

Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism 20110817 1

Superoxide is the single-electron reduction product of molecular oxygen generated by mitochondria and the innate immune enzyme complex, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox), and its isoforms. Initially identified as critical to the host defense against infection, superoxide has recently emerged as an important signaling molecule and as a proposed mediator of central nervous system injury in stroke, neurodegenerative conditions, and aging itself. Complete understandin ...[more]

PMID: 21847136

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Project description:Superoxide (O(2) (.-)) may function as a second messenger or regulator of signal transduction when produced at low concentrations in the proper locations within cells. The purpose of these studies was to determine whether human corneal stromal (HCS) fibroblasts are capable of producing O(2) (.-) via nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, a family of protein complexes believed to be responsible for the localized and limited production of O(2) (.-) with regulatory activity.HCS cells, grown as primary and low-passage cultures of fibroblasts, were used as the sources of RNA for reverse transcriptase PCR, with primers specific for mRNAs encoding the proteins that comprise NADPH oxidases. Small interfering (si)RNAs were used to knockdown specific NOX mRNAs. Proteins composing the NADPH oxidase complexes were identified using western blots. The production of O(2) (.-) by whole cells and cell-free preparations was assessed by measurement of NADPH-dependent superoxide dismutase-inhibitable cytochrome c reduction.Whole cells and cell-free extracts of corneal stromal fibroblasts produced O(2) (.-) in an NADPH-dependent manner. These fibroblasts constitutively produced mRNAs encoding eight proteins known to comprise NADPH oxidase complexes. mRNAs encoding NOX1, NOX4, NOX5, p22 phox, p47 phox, p67 phox, and p40 phox as well as Rac were expressed. Treatment of HCS fibroblasts with siRNA pools specific for each of these three NOXs significantly reduced the steady state levels of the respective mRNAs. Western blots confirmed the existence of all the proteins required for O(2) (.-) production. Rac 1, a regulator of the activity of some forms of NADPH complexes was present in membranous cell fractions containing the oxidase proteins.HCS fibroblasts produced O(2) (.-) in a NADPH-dependent manner via at least three isoforms of NADPH oxidase. These cells expressed NOX1, NOX4, NOX5, p22 phox, p47 phox, p67 phox, and p40 phox as well as Rac. SiRNAs directed against each of the three putative isoforms of NOX significantly reduced the steady state levels of the appropriate NOX mRNA pools, thus confirming the existence of the three isoforms. The O(2) (.-) produced by the NADPH oxidases in HCS fibroblasts is a potential contributor to signal transduction pathways and a regulator of gene expression as well as a potential participant in processes that occur during inflammation.

Dataset Information

Dynamic optical imaging of metabolic and NADPH oxidase-derived superoxide in live mouse brain using fluorescence lifetime unmixing.

Publications

Dynamic optical imaging of metabolic and NADPH oxidase-derived superoxide in live mouse brain using fluorescence lifetime unmixing.

Similar Datasets

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