scholarly journals Protection from mitochondrial complex II inhibition in vitro and in vivo by Nrf2-mediated transcription

2004 ◽  
Vol 102 (1) ◽  
pp. 244-249 ◽  
Author(s):  
M. J. Calkins ◽  
R. J. Jakel ◽  
D. A. Johnson ◽  
K. Chan ◽  
Y. W. Kan ◽  
...  
Keyword(s):  
Mitochondrial Complex ◽  
Complex Ii

scholarly journals The Nitrone Disodium 2,4-Sulphophenyl-N-Tert-Butylnitrone is Without Cytoprotective Effect on Sodium Nitroprusside-Induced Cell Death in N1E-115 Neuroblastoma Cells in vitro

2007 ◽  
Vol 28 (1) ◽  
pp. 24-28 ◽  
Author(s):  
Atticus H Hainsworth ◽  
Nasrin Bhuiyan ◽  
A Richard Green
Keyword(s):  
Cell Death ◽  
Free Radical ◽  
Sodium Nitroprusside ◽  
Neurovascular Unit ◽  
Neuroblastoma Cells ◽  
Mitochondrial Complex ◽  
Complex Ii ◽  
Radical Trapping

Disodium 2,4-sulphophenyl- N-tert-butylnitrone (NXY-059) is a novel free radical-trapping compound that is neuroprotective in both rodent and primate models of acute ischaemic stroke. Neuroprotection in vitro by NXY-059 has not been reported previously, and we have now investigated whether such an effect can be detected using a simple cell culture model of neurotoxicity. Neuron-like cells of the neuroblastoma-derived clonal cell line N1E-115 were exposed to the free radical-generating agent sodium nitroprusside (SNP), which produced a concentration-dependent reduction in mitochondrial complex II activity 24 h later (EC50 approximately 100 micromolar). Cell death induced by SNP (100 micromolar), assessed either by an increased proportion of apoptotic nuclear morphology or by mitochondrial complex II activity, was inhibited by a cocktail of known antioxidants (ascorbate, reduced glutathione, and dithiothreitol, all at 100 micromolar) but not by NXY-059 at a concentration known to be neuroprotective in vivo (300 micromolar). Disodium 2,4-sulphophenyl- N-tert-butylnitrone was also without effect on H2O2-mediated cytotoxicity. These results support recent data suggesting that in vivo NXY-059 probably acts at the neurovascular unit rather than at an intracellular site as a neuroprotective agent.

Azoxystrobin, a mitochondrial complex III Qo site inhibitor, exerts beneficial metabolic effects in vivo and in vitro

2014 ◽  
Vol 1840 (7) ◽  
pp. 2212-2221 ◽  
Author(s):  
An-Hui Gao ◽  
Yan-Yun Fu ◽  
Kun-Zhi Zhang ◽  
Mei Zhang ◽  
Hao-Wen Jiang ◽  
...  
Keyword(s):  
Complex Iii ◽  
Metabolic Effects ◽  
Mitochondrial Complex ◽  
Qo Site

scholarly journals Nm23H2 Facilitates Coat Protein Complex II Assembly and Endoplasmic Reticulum Export in Mammalian Cells

2005 ◽  
Vol 16 (2) ◽  
pp. 835-848 ◽  
Author(s):  
Lori Kapetanovich ◽  
Cassandra Baughman ◽  
Tina H. Lee
Keyword(s):  
Endoplasmic Reticulum ◽  
Coat Protein ◽  
Protein Complex ◽  
Mammalian Cells ◽  
Complex Ii ◽  
Permeabilized Cells ◽  
Er Export ◽  
Coat Protein Complex

The cytosolic coat protein complex II (COPII) mediates vesicle formation from the endoplasmic reticulum (ER) and is essential for ER-to-Golgi trafficking. The minimal machinery for COPII assembly is well established. However, additional factors may regulate the process in mammalian cells. Here, a morphological COPII assembly assay using purified COPII proteins and digitonin-permeabilized cells has been applied to demonstrate a role for a novel component of the COPII assembly pathway. The factor was purified and identified by mass spectrometry as Nm23H2, one of eight isoforms of nucleoside diphosphate kinase in mammalian cells. Importantly, recombinant Nm23H2, as well as a catalytically inactive version, promoted COPII assembly in vitro, suggesting a noncatalytic role for Nm23H2. Consistent with a function for Nm23H2 in ER export, Nm23H2 localized to a reticular network that also stained for the ER marker calnexin. Finally, an in vivo role for Nm23H2 in COPII assembly was confirmed by isoform-specific knockdown of Nm23H2 by using short interfering RNA. Knockdown of Nm23H2, but not its most closely related isoform Nm23H1, resulted in diminished COPII assembly at steady state and reduced kinetics of ER export. These results strongly suggest a previously unappreciated role for Nm23H2 in mammalian ER export.

scholarly journals Loss of the SdhB, but Not the SdhA, Subunit of Complex II Triggers Reactive Oxygen Species-Dependent Hypoxia-Inducible Factor Activation and Tumorigenesis

2007 ◽  
Vol 28 (2) ◽  
pp. 718-731 ◽  
Author(s):  
Robert D. Guzy ◽  
Bhumika Sharma ◽  
Eric Bell ◽  
Navdeep S. Chandel ◽  
Paul T. Schumacker
Keyword(s):  
Reactive Oxygen Species ◽  
Rna Interference ◽  
Growth Rates ◽  
Hypoxia Inducible Factor ◽  
Tumor Formation ◽  
Ros Production ◽  
Oxygen Species ◽  
Complex Ii

ABSTRACT Mitochondrial complex II is a tumor suppressor comprised of four subunits (SdhA, SdhB, SdhC, and SdhD). Mutations in any of these should disrupt complex II enzymatic activity, yet defects in SdhA produce bioenergetic deficiency while defects in SdhB, SdhC, or SdhD induce tumor formation. The mechanisms underlying these differences are not known. We show that the inhibition of distal subunits of complex II, either pharmacologically or via RNA interference of SdhB, increases normoxic reactive oxygen species (ROS) production, increases hypoxia-inducible factor alpha (HIF-α) stabilization in an ROS-dependent manner, and increases growth rates in vitro and in vivo without affecting hypoxia-mediated activation of HIF-α. Proximal pharmacologic inhibition or RNA interference of complex II at SdhA, however, does not increase normoxic ROS production or HIF-α stabilization and results in decreased growth rates in vitro and in vivo. Furthermore, the enhanced growth rates resulting from SdhB suppression are inhibited by the suppression of HIF-1α and/or HIF-2α, indicating that the mechanism of SdhB-induced tumor formation relies upon ROS production and subsequent HIF-α activation. Therefore, differences in ROS production, HIF proliferation, and cell proliferation contribute to the differences in tumor phenotype in cells lacking SdhB as opposed to those lacking SdhA.

scholarly journals Molecular mechanism and physiological role of active–deactive transition of mitochondrial complex I

2013 ◽  
Vol 41 (5) ◽  
pp. 1325-1330 ◽  
Author(s):  
Marion Babot ◽  
Alexander Galkin
Keyword(s):  
Complex I ◽  
Physiological Role ◽  
Protective Mechanism ◽  
Mitochondrial Complex I ◽  
Mitochondrial Complex ◽  
The Status ◽  
Nitric Oxide Metabolites

The unique feature of mitochondrial complex I is the so-called A/D transition (active–deactive transition). The A-form catalyses rapid oxidation of NADH by ubiquinone (k ~104 min−1) and spontaneously converts into the D-form if the enzyme is idle at physiological temperatures. Such deactivation occurs in vitro in the absence of substrates or in vivo during ischaemia, when the ubiquinone pool is reduced. The D-form can undergo reactivation given both NADH and ubiquinone availability during slow (k ~1–10 min−1) catalytic turnover(s). We examined known conformational differences between the two forms and suggested a mechanism exerting A/D transition of the enzyme. In addition, we discuss the physiological role of maintaining the enzyme in the D-form during the ischaemic period. Accumulation of the D-form of the enzyme would prevent reverse electron transfer from ubiquinol to FMN which could lead to superoxide anion generation. Deactivation would also decrease the initial burst of respiration after oxygen reintroduction. Therefore the A/D transition could be an intrinsic protective mechanism for lessening oxidative damage during the early phase of reoxygenation. Exposure of Cys39 of mitochondrially encoded subunit ND3 makes the D-form susceptible for modification by reactive oxygen species and nitric oxide metabolites which arrests the reactivation of the D-form and inhibits the enzyme. The nature of thiol modification defines deactivation reversibility, the reactivation timescale, the status of mitochondrial bioenergetics and therefore the degree of recovery of the ischaemic tissues after reoxygenation.

scholarly journals Deficiency of Mitochondrial Functions and Peroxidation of Frontoparietal Cortex Enhance Isoflurane Sensitivity in Aging Mice

2020 ◽  
Vol 12 ◽  
Author(s):  
Cansheng Gong ◽  
Donghang Zhang ◽  
Wei Ou ◽  
Mengchan Ou ◽  
Peng Liang ◽  
...  
Keyword(s):  
Lipid Oxidation ◽  
Mitochondrial Function ◽  
Protein Oxidation ◽  
General Anesthetics ◽  
Mitochondrial Complex ◽  
Complex Ii ◽  
Mitochondrial Functions ◽  
Frontoparietal Cortex ◽  
Antioxidative Therapy

Background: Hypersensitivity to general anesthetics may predict poor postoperative outcomes, especially among the older subjects. Therefore, it is essential to elucidate the mechanism underlying hypersensitivity to volatile anesthetics in the aging population. Given the fact that isoflurane sensitivity increases with aging, we hypothesized that deficiencies of mitochondrial function and elevated oxidative levels in the frontoparietal cortex may contribute to the enhanced sensitivity to isoflurane in aging mice.Methods: Isoflurane sensitivity in aging mice was determined by the concentration of isoflurane that is required for loss of righting reflex (LORR). Mitochondrial bioenergetics of the frontoparietal cortex was measured using a Seahorse XFp analyzer. Protein oxidation and lipid oxidation in the frontoparietal cortex were assessed using the Oxyblot protein oxidation detection kit and thiobarbituric acid reactive substance (TBARS) assay, respectively. Contributions of mitochondrial complex II inhibition by malonate and peroxidation by ozone to isoflurane sensitivity were tested in vivo. Besides, effects of antioxidative therapy on mitochondrial function and isoflurane sensitivity in mice were also measured.Results: The mean concentration of isoflurane that is required for LORR in aging mice (14–16 months old) was 0.83% ± 0.13% (mean ± SD, n = 80). Then, the mice were divided into three groups as sensitive group (S group, mean − SD), medium group (M group), and resistant group (R group, mean + SD) based on individual concentrations of isoflurane required for LORR. Activities of mitochondrial complex II and complex IV in mice of the S group were significantly lower than those of the R group, while frontoparietal cortical malondialdehyde (MDA) levels were higher in the mice of S group. Both inhibition of mitochondrial complexes and peroxidation significantly decreased the concentration of isoflurane that is required for LORR in vivo. After treatment with idebenone, the levels of lipid oxidation were alleviated and mitochondrial function was restored in aging mice. The concentration of isoflurane that required for LORR was also elevated after idebenone treatment.Conclusions: Decreased mitochondrial functions and higher oxidative stress levels in the frontoparietal cortex may contribute to the hypersensitivity to isoflurane in aging mice.

In Vitro and In Vivo Behaviour of Four Different 99(m)Tc-HEDP Complexes

1982 ◽  
Vol 21 (06) ◽  
pp. 227-231. ◽  
Author(s):  
T. Yamaguchi ◽  
I. Ikeda ◽  
O. Inoue
Keyword(s):  
Complex Iii ◽  
Alkaline Media ◽  
Organ Distribution ◽  
Air Oxidation ◽  
Complex Iv ◽  
Complex Ii ◽  
High Bone ◽  
Distribution Studies

According to absorption spectra, at least four different 99Tc-HEDP complexes [complex I (colorless), complex II (yellow), complex III (pink-red) and complex IV (brown)] were observed under various labeling conditions. Both pH and Sn (II)-HEDP concentration greatly influenced the formation of these complexes. In acidic or neutral media, complex II was the main product while in alkaline media complex III and complex IV were formed below concentration levels of 1 x 10–3M of Sn (II) and of 3x 10–3M of HEDP. At high Sn (II)-HEDP concentrations complexes I and II were formed, while complexes III and IV were found at lower Sn (II)-HEDP concentrations in weak alkaline media. All four 99(m)Tc-HEDP complexes were stable against air oxidation until at least 6 hrs after preparation. Complexes I and II were stable against dilution by distilled water, while complexes III and IV were unstable and readily dissociated. In organ distribution studies high soft-tissue uptakes were observed with complexes III and IV, while complexes I and II had high bone-seeking properties.

scholarly journals cFLIPL protects macrophages from LPS-induced pyroptosis via inhibition of complex II formation

Science ◽  
2020 ◽  
Vol 367 (6484) ◽  
pp. 1379-1384 ◽  
Author(s):  
Hayley I. Muendlein ◽  
David Jetton ◽  
Wilson M. Connolly ◽  
Keith P. Eidell ◽  
Zoie Magri ◽  
...  
Keyword(s):  
Cell Death ◽  
Pore Formation ◽  
Host Responses ◽  
Activated Macrophages ◽  
Danger Signal ◽  
Inhibitory Protein ◽  
Complex Ii ◽  
Conflicting Evidence

Cell death and inflammation are interdependent host responses to infection. During pyroptotic cell death, interleukin-1β (IL-1β) release occurs through caspase-1 and caspase-11–mediated gasdermin D pore formation. In vivo, responses to lipopolysaccharide (LPS) result in IL-1β secretion. In vitro, however, murine macrophages require a second “danger signal” for the inflammasome-driven maturation of IL-1β. Recent reports have shown caspase-8–mediated pyroptosis in LPS-activated macrophages but have provided conflicting evidence regarding the release of IL-1β under these conditions. Here, to further characterize the mechanism of LPS-induced secretion in vitro, we reveal an important role for cellular FLICE-like inhibitory protein (cFLIP) in the regulation of the inflammatory response. Specifically, we show that deficiency of the long isoform cFLIPL promotes complex II formation, driving pyroptosis, and the secretion of IL-1β in response to LPS alone.

scholarly journals Intrastriatal Neurotoxin Injections Reduce in Vitro and in Vivo Binding of Radiolabeled Rotenoids to Mitochondrial Complex I

1997 ◽  
Vol 17 (3) ◽  
pp. 265-272 ◽  
Author(s):  
Michael R. Kilbourn ◽  
Avgui Charalambous ◽  
Kirk A. Frey ◽  
Phillip Sherman ◽  
Donald S. Higgins ◽  
...  
Keyword(s):  
Quinolinic Acid ◽  
Complex I ◽  
Rat Striatum ◽  
Mitochondrial Complex I ◽  
Mitochondrial Complex ◽  
In Vivo Binding ◽  
Vitro Binding ◽  
Direct Competition

The in vivo and in vitro bindings of radiolabeled rotenoids to mitochondrial complex I of rat striatum were examined after unilateral intrastriatal injections of quinolinic acid or 1-methyl-4-phenylpyridinium salt (MPP+). Quinolinic acid produced significant, similar losses of in vivo binding of [11C]dihydrorotenol ([11C]DHROL: 40%) and in vitro binding of [3H]dihydrorotenone ([3H]DHR: 53%) in the injected striata at 13 days after the injection of neurotoxin. MPP+ reduced in vivo binding of [11C]DHROL (up to −55%) as measured 1.5 to 6 h after its administration. Reductions of in vivo [11C]DHROL binding after either quinolinic acid or MPP+ injections did not correlate with changes in striatal blood flow as measured with [14C]iodoantipyrine. These results are consistent with losses of complex I binding sites for radiolabeled rotenoids, produced using cell death (quinolinic acid) or direct competition for the binding site (MPP+). Appropriately radiolabeled rotenoids may be useful for in vivo imaging studies of changes of complex I in neurodegenerative diseases.

The Effect of Cd on Chlorophyll and Light-Harvesting Complex II Biosynthesis in Greening Plants

1999 ◽  
Vol 54 (9-10) ◽  
pp. 740-745 ◽  
Author(s):  
Leto Tziveleka ◽  
Athanassios Kaldis ◽  
Attila Hegedüs ◽  
Judit Kissimon ◽  
Anastasia Prombona ◽  
...  
Keyword(s):  
Phaseolus Vulgaris ◽  
Light Harvesting ◽  
Northern Hybridization ◽  
Total Chlorophyll ◽  
Intermittent Light ◽  
Light Harvesting Complex ◽  
Complex Ii ◽  
Light Harvesting Complex Ii

The effect of Cd on chlorophyll (Chl) as well as on light-harvesting complex II (LHCII) accumulation, has been examined during the early stages of development in etiolated Phaseolus vulgaris leaves exposed to intermittent light-dark cycles. We found that at the Cd concentrations studied, both Chl and LHCII accumulation were drastically reduced, although the LDS-solubilized total leaf protein level remained unaffected. However, on the basis of total chlorophyll present, the amount of stabilized LHCII was similar in both Cd-treated and nontreated samples. Additionally, the thylakoid-bound protease known to degrade LHCII, was found to be inhibited by Cd treatment both in vivo and in vitro. Finally, Northern hybridization analysis indicated that Cd affects LHCII accumulation by reducing drastically the steadystate level of Lhcb transcripts

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