Mutant Ubiquitin UBB+1 Induces Mitochondrial Fusion by Destabilizing Mitochondrial Fission-Specific Proteins and Confers Resistance to Oxidative Stress-Induced Cell Death in Astrocytic Cells

NME3 is a member of the nucleoside diphosphate kinase (NDPK) family that binds to the mitochondrial outer membrane to stimulate mitochondrial fusion. In this study, we showed that NME3 knockdown delayed DNA repair without reducing the cellular levels of nucleotide triphosphates. Further analyses revealed that NME3 knockdown increased fragmentation of mitochondria, which in turn led to mitochondrial oxidative stress-mediated DNA single-strand breaks (SSBs) in nuclear DNA. Re-expression of wild-type NME3 or inhibition of mitochondrial fission markedly reduced SSBs and facilitated DNA repair in NME3 knockdown cells, while expression of N-terminal deleted mutant defective in mitochondrial binding had no rescue effect. We further showed that disruption of mitochondrial fusion by knockdown of NME4 or MFN1 also caused mitochondrial oxidative stress-mediated genome instability. In conclusion, the contribution of NME3 to redox-regulated genome stability lies in its function in mitochondrial fusion.

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The calcilytic drug Calhex-231 ameliorates vascular hyporesponsiveness in traumatic hemorrhagic shock by inhibiting oxidative stress and mitochondrial fission

10.21203/rs.2.23868/v1 ◽

2020 ◽

Author(s):

Yan Lei ◽

Xiaoyong Peng ◽

Tao Li ◽

Liangming Liu ◽

Guangming Yang

Keyword(s):

Oxidative Stress ◽

Hemorrhagic Shock ◽

Vascular Reactivity ◽

Mitochondrial Fission ◽

Blood Perfusion ◽

Mitochondrial Fusion ◽

Vital Organ ◽

Animal Survival ◽

Traumatic Hemorrhagic Shock ◽

Mlc Phosphorylation

Abstract Background The calcium-sensing receptor (CaSR) plays a fundamental role in extracellular calcium homeostasis in humans. Surprisingly, CaSR is also expressed in non-homeostatic tissues and is involved in regulating diverse cellular functions. The objective of this study was to determine if Calhex-231 (Cal), a negative modulator of CaSR, may be beneficial in the treatment of traumatic hemorrhagic shock (THS) by improving cardiovascular function, and investigated its relationship to oxidative stress and the mitochondrial fusion-fission pathway. Methods Rats that had been subjected to traumatic hemorrhagic shock were used as models in this study. Hypoxia-treated vascular smooth muscle cells (VSMCs) were also used. The effects of Cal on cardiovascular function, animal survival, hemodynamic parameters, and vital organ function in THS rats were observed, and the relationship to oxidative stress and mitochondrial fusion-fission was investigated. Results Cal significantly improved hemodynamics, elevated blood pressure, increased vital organ blood perfusion and local oxygen supply, and markedly improved the survival outcomes of THS rats. Furthermore, Cal significantly improved vascular reactivity after THS, including the pressor response of THS rats to norepinephrine (NE), and also the contractile response of superior mesenteric arteries, mesenteric arterioles, and isolated VSMCs to NE. Cal also restored the THS-induced decrease in myosin light chain (MLC) phosphorylation, which is the principal mechanism responsible for VSMC contraction and vascular reactivity. Inhibition of MLC phosphorylation antagonized the Cal-induced restoration of vascular reactivity following THS. Cal decreased oxidative stress indexes and increased antioxidant enzyme levels in THS rats, and also reduced reactive oxygen species levels in hypoxic VSMCs. In addition, THS induced expression of mitochondrial fission proteins Drp1 and Fis1, and decreased expression of mitochondrial fusion protein Mfn1 in vascular tissues. Cal reduced expression of Drp1 and Fis1, but did not affect Mfn1 expression. In hypoxic VSMCs, Cal inhibited hypoxia-induced mitochondrial fragmentation and preserved mitochondrial morphology. Conclusions Calhex-231 exhibits outstanding potential for effective therapy of traumatic hemorrhagic shock, due to its ability to improve hemodynamics, increase vital organ blood perfusion, and markedly prolong animal survival. These beneficial effects result from its protection of vascular function via inhibition of oxidative stress and mitochondrial fission.

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T-2 Toxin-Induced Oxidative Stress Leads to Imbalance of Mitochondrial Fission and Fusion to Activate Cellular Apoptosis in the Human Liver 7702 Cell Line

Toxins ◽

10.3390/toxins12010043 ◽

2020 ◽

Vol 12 (1) ◽

pp. 43 ◽

Cited By ~ 5

Author(s):

Junhua Yang ◽

Wenbo Guo ◽

Jianhua Wang ◽

Xianli Yang ◽

Zhiqi Zhang ◽

...

Keyword(s):

Oxidative Stress ◽

Cell Apoptosis ◽

Human Liver ◽

Mitochondrial Dynamics ◽

Mitochondrial Fission ◽

Mitochondrial Fusion ◽

Mitochondrial Dynamic ◽

Normal Human Liver ◽

Induced Apoptosis

T-2 toxin, as a highly toxic mycotoxin to humans and animals, induces oxidative stress and apoptosis in various cells and tissues. Apoptosis and mitochondrial fusion/fission are two tightly interconnected processes that are crucial for maintaining physiological homeostasis. However, the role of mitochondrial fusion/fission in apoptosis of T-2 toxin remains unknown. Hence, we aimed to explore the putative role of mitochondrial fusion/fission on T-2 toxin induced apoptosis in normal human liver (HL-7702) cells. T-2 toxin treatment (0, 0.1, 1.0, or 10 μg/L) for 24 h caused decreased cell viability and ATP concentration and increased production of (ROS), as seen by a loss of mitochondrial membrane potential (∆Ψm) and increase in mitochondrial fragmentation. Subsequently, the mitochondrial dynamic imbalance was activated, evidenced by a dose-dependent decrease and increase in the protein expression of mitochondrial fusion (OPA1, Mfn1, and Mfn2) and fission (Drp1 and Fis1), respectively. Furthermore, the T-2 toxin promoted the release of cytochrome c from mitochondria to cytoplasm and induced cell apoptosis triggered by upregulation of Bax and Bax/Bcl-2 ratios, and further activated the caspase pathways. Taken together, these results indicate that altered mitochondrial dynamics induced by oxidative stress with T-2 toxin exposure likely contribute to mitochondrial injury and HL-7702 cell apoptosis.

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Fzo1, a Protein Involved in Mitochondrial Fusion, Inhibits Apoptosis

Journal of Biological Chemistry ◽

10.1074/jbc.m408910200 ◽

2004 ◽

Vol 279 (50) ◽

pp. 52726-52734 ◽

Cited By ~ 245

Author(s):

Rie Sugioka ◽

Shigeomi Shimizu ◽

Yoshihide Tsujimoto

Keyword(s):

Cell Death ◽

Conformational Changes ◽

Apoptotic Cell ◽

Mitochondrial Fission ◽

Apoptotic Cell Death ◽

Mitochondrial Fusion ◽

Mitochondrial Morphology ◽

Human Homolog ◽

Mitochondrial Fragmentation ◽

Apoptotic Death

Mitochondrial morphology and physiology are regulated by the processes of fusion and fission. Some forms of apoptosis are reported to be associated with mitochondrial fragmentation. We showed that overexpression of Fzo1A/B (rat) proteins involved in mitochondrial fusion, or silencing of Dnm1 (rat)/Drp1 (human) (a mitochondrial fission protein), increased elongated mitochondria in healthy cells. After apoptotic stimulation, these interventions inhibited mitochondrial fragmentation and cell death, suggesting that a process involved in mitochondrial fusion/fission might play a role in the regulation of apoptosis. Consistently, silencing of Fzo1A/B or Mfn1/2 (a human homolog of Fzo1A/B) led to an increase of shorter mitochondria and enhanced apoptotic death. Overexpression of Fzo1 inhibited cytochromecrelease and activation of Bax/Bak, as assessed from conformational changes and oligomerization. Silencing of Mfn or Drp1 caused an increase or decrease of mitochondrial sensitivity to apoptotic stimulation, respectively. These results indicate that some of the proteins involved in mitochondrial fusion/fission modulate apoptotic cell death at the mitochondrial level.

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Med13p prevents mitochondrial fission and programmed cell death in yeast through nuclear retention of cyclin C

Molecular Biology of the Cell ◽

10.1091/mbc.e14-05-0953 ◽

2014 ◽

Vol 25 (18) ◽

pp. 2807-2816 ◽

Cited By ~ 25

Author(s):

Svetlana Khakhina ◽

Katrina F. Cooper ◽

Randy Strich

Keyword(s):

Oxidative Stress ◽

Cell Death ◽

Programmed Cell Death ◽

Mitochondrial Fission ◽

Regulatory System ◽

Stress Sensitivity ◽

26S Proteasome ◽

Mitochondrial Fragmentation ◽

Nuclear Retention ◽

Cyclin C

The yeast cyclin C-Cdk8 kinase forms a complex with Med13p to repress the transcription of genes involved in the stress response and meiosis. In response to oxidative stress, cyclin C displays nuclear to cytoplasmic relocalization that triggers mitochondrial fission and promotes programmed cell death. In this report, we demonstrate that Med13p mediates cyclin C nuclear retention in unstressed cells. Deleting MED13 allows aberrant cytoplasmic cyclin C localization and extensive mitochondrial fragmentation. Loss of Med13p function resulted in mitochondrial dysfunction and hypersensitivity to oxidative stress–induced programmed cell death that were dependent on cyclin C. The regulatory system controlling cyclin C-Med13p interaction is complex. First, a previous study found that cyclin C phosphorylation by the stress-activated MAP kinase Slt2p is required for nuclear to cytoplasmic translocation. This study found that cyclin C-Med13p association is impaired when the Slt2p target residue is substituted with a phosphomimetic amino acid. The second step involves Med13p destruction mediated by the 26S proteasome and cyclin C-Cdk8p kinase activity. In conclusion, Med13p maintains mitochondrial structure, function, and normal oxidative stress sensitivity through cyclin C nuclear retention. Releasing cyclin C from the nucleus involves both its phosphorylation by Slt2p coupled with Med13p destruction.

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Novel Mitochondrial Targets for Neuroprotection

Journal of Cerebral Blood Flow & Metabolism ◽

10.1038/jcbfm.2012.32 ◽

2012 ◽

Vol 32 (7) ◽

pp. 1362-1376 ◽

Cited By ~ 99

Author(s):

Miguel A Perez-Pinzon ◽

R Anne Stetler ◽

Gary Fiskum

Keyword(s):

Oxidative Stress ◽

Cell Death ◽

Mitochondrial Fission ◽

Permeability Transition Pore ◽

Permeability Transition ◽

Mitochondrial Proteins ◽

Neuronal Necrosis ◽

Mitochondrial Energy Metabolism ◽

Neurologic Disorders ◽

Transport Chain

Mitochondrial dysfunction contributes to the pathophysiology of acute neurologic disorders and neurodegenerative diseases. Bioenergetic failure is the primary cause of acute neuronal necrosis, and involves excitotoxicity-associated mitochondrial Ca2+ overload, resulting in opening of the inner membrane permeability transition pore and inhibition of oxidative phosphorylation. Mitochondrial energy metabolism is also very sensitive to inhibition by reactive O2 and nitrogen species, which modify many mitochondrial proteins, lipids, and DNA/RNA, thus impairing energy transduction and exacerbating free radical production. Oxidative stress and Ca2+-activated calpain protease activities also promote apoptosis and other forms of programmed cell death, primarily through modification of proteins and lipids present at the outer membrane, causing release of proapoptotic mitochondrial proteins, which initiate caspase-dependent and caspase-independent forms of cell death. This review focuses on three classifications of mitochondrial targets for neuroprotection. The first is mitochondrial quality control, maintained by the dynamic processes of mitochondrial fission and fusion and autophagy of abnormal mitochondria. The second includes targets amenable to ischemic preconditioning, e.g., electron transport chain components, ion channels, uncoupling proteins, and mitochondrial biogenesis. The third includes mitochondrial proteins and other molecules that defend against oxidative stress. Each class of targets exhibits excellent potential for translation to clinical neuroprotection.

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Abstract 393: MCL-1 Promotes Survival and Influences Mitochondrial Dynamics in Cardiac Myocytes

Circulation Research ◽

10.1161/res.117.suppl_1.393 ◽

2015 ◽

Vol 117 (suppl_1) ◽

Author(s):

Alexandra G Moyzis ◽

Robert L Thomas ◽

Jennifer Kuo ◽

Åsa B Gustafsson

Keyword(s):

Cell Death ◽

Cardiac Myocytes ◽

Apoptotic Cell ◽

Mitochondrial Dynamics ◽

Mitochondrial Fission ◽

Apoptotic Cell Death ◽

Mitochondrial Fusion ◽

Mitochondrial Outer Membrane ◽

Mitochondrial Morphology ◽

Rapid Degradation

The BCL-2 family proteins are important regulators of mitochondrial structure and integrity. MCL-1 is an anti-apoptotic BCL-2 protein that is highly expressed in the myocardium compared to the other anti-apoptotic proteins BCL-2 and BCL-X L. Recently, we reported that MCL-1 is essential for myocardial homeostasis. Cardiac-specific deletion of MCL-1 in mice led to rapid mitochondrial dysfunction, hypertrophy, and lethal cardiomyopathy. Surprisingly, MCL-1 deficient myocytes did not undergo apoptotic cell death. Instead, the cells displayed signs of mitochondrial deterioration and necrotic cell death, suggesting that MCL-1 has an additional role in maintaining mitochondrial function in cardiac myocytes. Similarly, deletion of MCL-1 in fibroblasts caused rapid mitochondrial fragmentation followed by cell death at 72 hours. Interestingly, the MCL-1 deficient fibroblasts retained cytochrome c in the mitochondria , confirming that the cells were not undergoing apoptotic cell death. We have also identified that MCL-1 localizes to the mitochondrial outer membrane (OM) and the matrix in the myocardium and that the two forms respond differently to stress. MCL-1 OM was rapidly degraded after myocardial infarction or fasting, whereas MCL-1 Matrix levels were maintained. Similarly, starvation of MEFs resulted in rapid degradation of MCL-1 OM , whereas MCL-1 Matrix showed delayed degradation. Treatment with the mitochondrial uncoupler FCCP led to rapid degradation of both forms. This suggests that the susceptibility to degradation is dependent on its localization and the nature of the stress. Our data also suggests that these two forms perform distinct functions in regulating mitochondrial morphology and survival. Overexpression of MCL-1 Matrix promoted mitochondrial fusion in fibroblasts under baseline conditions and protected cells against FCCP-mediated mitochondrial fission and clearance by autophagosomes. Thus, our data suggest that MCL-1 exists in two separate locations where it performs different functions. MCL-1 Matrix promotes mitochondrial fusion, which protects cells against excessive mitochondrial clearance during unfavorable conditions.

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DRP1-dependent apoptotic mitochondrial fission occurs independently of BAX, BAK and APAF1 to amplify cell death by BID and oxidative stress

Biochimica et Biophysica Acta (BBA) - Bioenergetics ◽

10.1016/j.bbabio.2016.03.016 ◽

2016 ◽

Vol 1857 (8) ◽

pp. 1267-1276 ◽

Cited By ~ 30

Author(s):

Björn Oettinghaus ◽

Donato D'Alonzo ◽

Elisa Barbieri ◽

Lisa Michelle Restelli ◽

Claudia Savoia ◽

...

Keyword(s):

Oxidative Stress ◽

Cell Death ◽

Mitochondrial Fission ◽

And Oxidative Stress

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Neuroprotective Effects of a Small Mitochondrially-Targeted Tetrapeptide Elamipretide in Neurodegeneration

Frontiers in Integrative Neuroscience ◽

10.3389/fnint.2021.747901 ◽

2022 ◽

Vol 15 ◽

Author(s):

Nguyen Thanh Nhu ◽

Shu-Yun Xiao ◽

Yijie Liu ◽

V. Bharath Kumar ◽

Zhen-Yang Cui ◽

...

Keyword(s):

Oxidative Stress ◽

Mitochondrial Biogenesis ◽

Mitochondrial Respiration ◽

Mitochondrial Fission ◽

Mitochondrial Fusion ◽

Protein Accumulation ◽

Therapeutic Effects ◽

Neuroprotective Effects ◽

Toxic Protein ◽

Neural Apoptosis

Neural mitochondrial dysfunction, neural oxidative stress, chronic neuroinflammation, toxic protein accumulation, and neural apoptosis are common causes of neurodegeneration. Elamipretide, a small mitochondrially-targeted tetrapeptide, exhibits therapeutic effects and safety in several mitochondria-related diseases. In neurodegeneration, extensive studies have shown that elamipretide enhanced mitochondrial respiration, activated neural mitochondrial biogenesis via mitochondrial biogenesis regulators (PCG-1α and TFAM) and the translocate factors (TOM-20), enhanced mitochondrial fusion (MNF-1, MNF-2, and OPA1), inhibited mitochondrial fission (Fis-1 and Drp-1), as well as increased mitophagy (autophagy of mitochondria). In addition, elamipretide has been shown to attenuate neural oxidative stress (hydrogen peroxide, lipid peroxidation, and ROS), neuroinflammation (TNF, IL-6, COX-2, iNOS, NLRP3, cleaved caspase-1, IL-1β, and IL-18), and toxic protein accumulation (Aβ). Consequently, elamipretide could prevent neural apoptosis (cytochrome c, Bax, caspase 9, and caspase 3) and enhance neural pro-survival (Bcl2, BDNF, and TrkB) in neurodegeneration. These findings suggest that elamipretide may prevent the progressive development of neurodegenerative diseases via enhancing mitochondrial respiration, mitochondrial biogenesis, mitochondrial fusion, and neural pro-survival pathway, as well as inhibiting mitochondrial fission, oxidative stress, neuroinflammation, toxic protein accumulation, and neural apoptosis. Elamipretide or mitochondrially-targeted peptide might be a targeted agent to attenuate neurodegenerative progression.

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