Mitochondrial and redox modifications in early stages of Huntington disease

Defects in mitochondrial function and mitochondrial-related redox deregulation have been attributed to Huntington disease (HD), a genetic neurodegenerative disorder largely affecting the striatum. However, whether these changes occur in early stages of the disease and can be detected in vivo is still unclear. Thus, in the present study, we analyzed changes in mitochondrial function and overreduced states associated with production of reactive oxygen species (ROS) at early stages and along disease progression in vivo in the brain by positron emission tomography (PET) and in skin fibroblasts of premanifest/early and manifest HD patients, and in YAC128 transgenic mouse brain (striatum and cortex) at early-symptomatic (3 month-old, mo) and symptomatic (6 to 12 mo) stages. In vivo human and mouse brain PET imaging was assessed using [64Cu]-ATSM; analysis of oxygen consumption rates was assessed by Seahorse analysis, hydrogen peroxide levels were determined using fluorescent probes and mitochondrial morphology by transmission electron microscopy in human skin fibroblasts and mouse striatal and cortical isolated mitochondria. Premanifest and prodromal HD carriers exhibited enhanced whole-brain (with exception of caudate) [64Cu]-ATSM labelling, correlating with CAG repeat number, concomitantly with enhanced basal and maximal respiration, proton (H+) leak and increased hydrogen peroxide levels, the later progressing to advanced HD stage, in human fibroblasts. Mitochondria from fibroblasts of premanifest HD carriers also showed reduced roundness, while higher number of mitochondrial DNA copies correlated with maximal respiratory capacity. In vivo animal PET analysis showed increased accumulation of [64Cu]-ATSM in YAC128 mouse striatum. Pre/early-symptomatic YAC128 mouse striatal, but not cortical, isolated mitochondria exhibited a rise in basal and maximal mitochondrial respiration and in ATP production along with increased complex II and III activities, enhanced mitochondrial hydrogen peroxide and roundness, as revealed by brain ultrastructure analysis, further presenting defects in Ca2+ handling, supporting increased striatal susceptibility in the YAC128 mouse model. Data demonstrate both human and mouse mitochondrial overactivity and altered morphology at early HD stages, facilitating redox unbalance, the latter extending over late disease stages.

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PEROXIDASE-MEDIATED MAMMALIAN CELL CYTOTOXICITY

Journal of Experimental Medicine ◽

10.1084/jem.138.1.318 ◽

1973 ◽

Vol 138 (1) ◽

pp. 318-323 ◽

Cited By ~ 51

Author(s):

Paul J. Edelson ◽

Zanvil A. Cohn

Keyword(s):

Hydrogen Peroxide ◽

Cell Death ◽

Mammalian Cell ◽

Lymphoid Cells ◽

Cell Cytotoxicity ◽

Inflammatory Exudate ◽

Cell Association ◽

Human And Mouse ◽

Monocytes And Lymphocytes

Lactoperoxidase, in the presence of hydrogen peroxide and iodide is cytotoxic for human and mouse lymphoid cells, and human erythrocytes. Myeloperoxidase, in amounts equivalent to 1.5 x 106 neutrophils, readily replaces lactoperoxidase, and allows the substitution of the iodide ion by chloride. The myeloperoxidase-mediated reaction is rapid, and highly efficient, leading to 85–90% cell death in 90 min, as measured by 51chromium release and dye exclusion. The mixture of granulocytes. monocytes, and lymphocytes present in an inflammatory exudate, and the intimate cell-to-cell association characteristic of cytotoxic phenomena may provide the in vivo requirements for such a system.

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Mechanisms of the interaction of nitroxyl with mitochondria

Biochemical Journal ◽

10.1042/bj20031758 ◽

2004 ◽

Vol 379 (2) ◽

pp. 359-366 ◽

Cited By ~ 51

Author(s):

Sruti SHIVA ◽

Jack H. CRAWFORD ◽

Anup RAMACHANDRAN ◽

Erin K. CEASER ◽

Tess HILLSON ◽

...

Keyword(s):

Mitochondrial Function ◽

Mitochondrial Protein ◽

Present Evidence ◽

Physiological Regulation ◽

Isolated Mitochondria ◽

Angeli's Salt ◽

Biological Responses ◽

Protein Thiols ◽

Proteomics Approach

It is now thought that NO• (nitric oxide) and its redox congeners may play a role in the physiological regulation of mitochondrial function. The inhibition of cytochrome c oxidase by NO• is characterized as being reversible and oxygen dependent. In contrast, peroxynitrite, the product of the reaction of NO• with superoxide, irreversibly inhibits several of the respiratory complexes. However, little is known about the effects of HNO (nitroxyl) on mitochondrial function. This is especially important, since HNO has been shown to be more cytotoxic than NO•, may potentially be generated in vivo, and elicits biological responses with some of the characteristics of NO and peroxynitrite. In the present study, we present evidence that isolated mitochondria, in the absence or presence of substrate, convert HNO into NO• by a process that is dependent on mitochondrial concentration as well as the concentration of the HNO donor Angeli's salt. In addition, HNO is able to inhibit mitochondrial respiration through the inhibition of complexes I and II, most probably via modification of specific cysteine residues in the proteins. Using a proteomics approach, extensive modification of mitochondrial protein thiols was demonstrated. From these data it is evident that HNO interacts with mitochondria through mechanisms distinct from those of either NO• or peroxynitrite, including the generation of NO•, the modification of thiols and the inhibition of complexes I and II.

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Generation of superoxide and hydrogen peroxide by side reactions of mitochondrial 2-oxoacid dehydrogenase complexes in isolation and in cells

Biological Chemistry ◽

10.1515/hsz-2017-0284 ◽

2018 ◽

Vol 399 (5) ◽

pp. 407-420 ◽

Cited By ~ 10

Author(s):

Victoria I. Bunik ◽

Martin D. Brand

Keyword(s):

Hydrogen Peroxide ◽

Side Reactions ◽

Isolated Mitochondria ◽

Pathological Conditions ◽

High Maximum ◽

Generate Superoxide Anion ◽

Branched Chain ◽

Enzyme Complexes ◽

In Cells

Abstract Mitochondrial 2-oxoacid dehydrogenase complexes oxidize 2-oxoglutarate, pyruvate, branched-chain 2-oxoacids and 2-oxoadipate to the corresponding acyl-CoAs and reduce NAD+ to NADH. The isolated enzyme complexes generate superoxide anion radical or hydrogen peroxide in defined reactions by leaking electrons to oxygen. Studies using isolated mitochondria in media mimicking cytosol suggest that the 2-oxoacid dehydrogenase complexes contribute little to the production of superoxide or hydrogen peroxide relative to other mitochondrial sites at physiological steady states. However, the contributions may increase under pathological conditions, in accordance with the high maximum capacities of superoxide or hydrogen peroxide-generating reactions of the complexes, established in isolated mitochondria. We assess available data on the use of modulations of enzyme activity to infer superoxide or hydrogen peroxide production from particular 2-oxoacid dehydrogenase complexes in cells, and limitations of such methods to discriminate specific superoxide or hydrogen peroxide sources in vivo.

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Comparison of in vivo postexercise phosphocreatine recovery and resting ATP synthesis flux for the assessment of skeletal muscle mitochondrial function

AJP Cell Physiology ◽

10.1152/ajpcell.00200.2010 ◽

2010 ◽

Vol 299 (5) ◽

pp. C1136-C1143 ◽

Cited By ~ 30

Author(s):

N. M. A. van den Broek ◽

J. Ciapaite ◽

K. Nicolay ◽

J. J. Prompers

Keyword(s):

Skeletal Muscle ◽

Oxygen Consumption ◽

Mitochondrial Dysfunction ◽

Mitochondrial Function ◽

Atp Synthesis ◽

Resonance Spectroscopy ◽

Isolated Mitochondria ◽

Significant Difference

31P magnetic resonance spectroscopy (MRS) has been used to assess skeletal muscle mitochondrial function in vivo by measuring 1) phosphocreatine (PCr) recovery after exercise or 2) resting ATP synthesis flux with saturation transfer (ST). In this study, we compared both parameters in a rat model of mitochondrial dysfunction with the aim of establishing the most appropriate method for the assessment of in vivo muscle mitochondrial function. Mitochondrial dysfunction was induced in adult Wistar rats by daily subcutaneous injections with the complex I inhibitor diphenyleneiodonium (DPI) for 2 wk. In vivo 31P MRS measurements were supplemented by in vitro measurements of oxygen consumption in isolated mitochondria. Two weeks of DPI treatment induced mitochondrial dysfunction, as evidenced by a 20% lower maximal ADP-stimulated oxygen consumption rate in isolated mitochondria from DPI-treated rats oxidizing pyruvate plus malate. This was paralleled by a 46% decrease in in vivo oxidative capacity, determined from postexercise PCr recovery. Interestingly, no significant difference in resting, ST-based ATP synthesis flux was observed between DPI-treated rats and controls. These results show that PCr recovery after exercise has a more direct relationship with skeletal muscle mitochondrial function than the ATP synthesis flux measured with 31P ST MRS in the resting state.

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Comprehensive assessment of mitochondrial respiratory function in freshly isolated nephron segments

AJP Renal Physiology ◽

10.1152/ajprenal.00031.2020 ◽

2020 ◽

Vol 318 (5) ◽

pp. F1237-F1245

Author(s):

Allison McCrimmon ◽

Mark Domondon ◽

Regina F. Sultanova ◽

Daria V. Ilatovskaya ◽

Krisztian Stadler

Keyword(s):

Oxygen Consumption ◽

Mitochondrial Function ◽

Respiratory Function ◽

Rapid Assessment ◽

Acute Injury ◽

Mitochondrial Oxygen Consumption ◽

Isolated Mitochondria ◽

Proximal Tubular ◽

Mitochondrial Respiratory

Changes in mitochondrial function are central to many forms of kidney disease, including acute injury, diabetic nephropathy, hypertension, and chronic kidney diseases. As such, there is an increasing need for reliable and fast methods for assessing mitochondrial respiratory function in renal cells. Despite being indispensable for many mechanistic studies, cultured cells or isolated mitochondria, however, often do not recapitulate in vivo or close to in vivo situations. Cultured and/or immortalized cells often change their bioenergetic profile and phenotype compared with in vivo or ex vivo situations, and isolated mitochondria are simply removed from their cellular milieu. This is especially important for extremely complex organs such as the kidney. Here, we report the development and validation of a new approach for the rapid assessment of mitochondrial oxygen consumption on freshly isolated glomeruli or proximal tubular fragments using Agilent SeaHorse XFe24 and XF96 Extracellular Flux Analyzers. We validated the technique in several healthy and diseased rodent models: the C57BL/6J mouse, the diabetic db/ db mouse and matching db/+ control mouse, and the Dahl salt-sensitive rat. We compared the data to respiration from isolated mitochondria. The method can be adapted and used for the rapid assessment of mitochondrial oxygen consumption from any rodent model of the investigator’s choice. The isolation methods presented here ensure viable and functional proximal tubular fragments and glomeruli, with a preserved cellular environment for studying mitochondrial function within the context of their surroundings and interactions.

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HACE1 is essential for astrocyte mitochondrial function and influences Huntington disease phenotypes in vivo

Human Molecular Genetics ◽

10.1093/hmg/ddx394 ◽

2017 ◽

Vol 27 (2) ◽

pp. 239-253 ◽

Cited By ~ 4

Author(s):

Dagmar E Ehrnhoefer ◽

Amber L Southwell ◽

Meenalochani Sivasubramanian ◽

Xiaofan Qiu ◽

Erika B Villanueva ◽

...

Keyword(s):

Mitochondrial Function ◽

Huntington Disease ◽

Disease Phenotypes

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Fluorescent proteins for in vivo imaging, where's the biliverdin?

Biochemical Society Transactions ◽

10.1042/bst20200444 ◽

2020 ◽

Vol 48 (6) ◽

pp. 2657-2667

Author(s):

Felipe Montecinos-Franjola ◽

John Y. Lin ◽

Erik A. Rodriguez

Keyword(s):

Hydrogen Peroxide ◽

In Vivo Imaging ◽

Near Infrared ◽

Fluorescent Protein ◽

Fluorescent Proteins ◽

Fluorescent Imaging ◽

Infrared Light ◽

Red Fluorescent Protein ◽

Color Palette

Noninvasive fluorescent imaging requires far-red and near-infrared fluorescent proteins for deeper imaging. Near-infrared light penetrates biological tissue with blood vessels due to low absorbance, scattering, and reflection of light and has a greater signal-to-noise due to less autofluorescence. Far-red and near-infrared fluorescent proteins absorb light >600 nm to expand the color palette for imaging multiple biosensors and noninvasive in vivo imaging. The ideal fluorescent proteins are bright, photobleach minimally, express well in the desired cells, do not oligomerize, and generate or incorporate exogenous fluorophores efficiently. Coral-derived red fluorescent proteins require oxygen for fluorophore formation and release two hydrogen peroxide molecules. New fluorescent proteins based on phytochrome and phycobiliproteins use biliverdin IXα as fluorophores, do not require oxygen for maturation to image anaerobic organisms and tumor core, and do not generate hydrogen peroxide. The small Ultra-Red Fluorescent Protein (smURFP) was evolved from a cyanobacterial phycobiliprotein to covalently attach biliverdin as an exogenous fluorophore. The small Ultra-Red Fluorescent Protein is biophysically as bright as the enhanced green fluorescent protein, is exceptionally photostable, used for biosensor development, and visible in living mice. Novel applications of smURFP include in vitro protein diagnostics with attomolar (10−18 M) sensitivity, encapsulation in viral particles, and fluorescent protein nanoparticles. However, the availability of biliverdin limits the fluorescence of biliverdin-attaching fluorescent proteins; hence, extra biliverdin is needed to enhance brightness. New methods for improved biliverdin bioavailability are necessary to develop improved bright far-red and near-infrared fluorescent proteins for noninvasive imaging in vivo.

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