scholarly journals Loss of OMA1 delays neurodegeneration by preventing stress-induced OPA1 processing in mitochondria

2016 ◽  
Vol 212 (2) ◽  
pp. 157-166 ◽  
Author(s):  
Anne Korwitz ◽  
Carsten Merkwirth ◽  
Ricarda Richter-Dennerlein ◽  
Simon E. Tröder ◽  
Hans-Georg Sprenger ◽  
...  
Keyword(s):  
Mitochondrial Genome ◽  
Respiratory Chain ◽  
Neuronal Death ◽  
Neuronal Survival ◽  
Neuronal Loss ◽  
Proteolytic Cleavage ◽  
Mitochondrial Morphology ◽  
Guanosine Triphosphatase

Proteolytic cleavage of the dynamin-like guanosine triphosphatase OPA1 in mitochondria is emerging as a central regulatory hub that determines mitochondrial morphology under stress and in disease. Stress-induced OPA1 processing by OMA1 triggersmitochondrial fragmentation, which is associated with mitophagy and apoptosis in vitro. Here, we identify OMA1 as a critical regulator of neuronal survival in vivo and demonstrate that stress-induced OPA1 processing by OMA1 promotes neuronal death and neuroinflammatory responses. Using mice lacking prohibitin membrane scaffolds as a model of neurodegeneration, we demonstrate that additional ablation of Oma1 delays neuronal loss and prolongs lifespan. This is accompanied by the accumulation of fusion-active, long OPA1 forms, which stabilize the mitochondrial genome but do not preserve mitochondrial cristae or respiratory chain supercomplex assembly in prohibitin-depleted neurons. Thus, long OPA1 forms can promote neuronal survival independently of cristae shape, whereas stress-induced OMA1 activation and OPA1 cleavage limit mitochondrial fusion and promote neuronal death.

scholarly journals Overexpression of Mitochondrial Calcium Uniporter Causes Neuronal Death

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Veronica Granatiero ◽  
Marco Pacifici ◽  
Anna Raffaello ◽  
Diego De Stefani ◽  
Rosario Rizzuto
Keyword(s):  
Cell Fate ◽  
Neuronal Death ◽  
Cortical Neurons ◽  
Neuronal Cell Death ◽  
Neuronal Cell ◽  
Neuronal Loss ◽  
Calcium Uniporter ◽  
Organelle Morphology

Neurodegenerative diseases are a large and heterogeneous group of disorders characterized by selective and progressive death of specific neuronal subtypes. In most of the cases, the pathophysiology is still poorly understood, although a number of hypotheses have been proposed. Among these, dysregulation of Ca2+ homeostasis and mitochondrial dysfunction represent two broadly recognized early events associated with neurodegeneration. However, a direct link between these two hypotheses can be drawn. Mitochondria actively participate to global Ca2+ signaling, and increases of [Ca2+] inside organelle matrix are known to sustain energy production to modulate apoptosis and remodel cytosolic Ca2+ waves. Most importantly, while mitochondrial Ca2+ overload has been proposed as the no-return signal, triggering apoptotic or necrotic neuronal death, until now direct evidences supporting this hypothesis, especially in vivo, are limited. Here, we took advantage of the identification of the mitochondrial Ca2+ uniporter (MCU) and tested whether mitochondrial Ca2+ signaling controls neuronal cell fate. We overexpressed MCU both in vitro, in mouse primary cortical neurons, and in vivo, through stereotaxic injection of MCU-coding adenoviral particles in the brain cortex. We first measured mitochondrial Ca2+ uptake using quantitative genetically encoded Ca2+ probes, and we observed that the overexpression of MCU causes a dramatic increase of mitochondrial Ca2+ uptake both at resting and after membrane depolarization. MCU-mediated mitochondrial Ca2+ overload causes alteration of organelle morphology and dysregulation of global Ca2+ homeostasis. Most importantly, MCU overexpression in vivo is sufficient to trigger gliosis and neuronal loss. Overall, we demonstrated that mitochondrial Ca2+ overload is per se sufficient to cause neuronal cell death both in vitro and in vivo, thus highlighting a potential key step in neurodegeneration.

scholarly journals Inhibition of microRNA-181 Reduces Forebrain Ischemia-Induced Neuronal Loss

2013 ◽  
Vol 33 (12) ◽  
pp. 1976-1982 ◽  
Author(s):  
Jeong-mi Moon ◽  
Lijun Xu ◽  
Rona G Giffard
Keyword(s):  
Cell Death ◽  
Neuronal Survival ◽  
Infarct Volume ◽  
Glutamate Transporter ◽  
Neuronal Loss ◽  
Male Rats ◽  
Global Cerebral Ischemia ◽  
Forebrain Ischemia

MicroRNA (miRNA), miR-181a, is enriched in the brain, and inhibition of miR-181a reduced astrocyte death in vitro and infarct volume after stroke in vivo. This study investigated the role of miR-181a in neuronal injury in vitro and hippocampal neuronal loss in vivo after forebrain ischemia. miR-181a levels were altered by transfection with mimic or antagomir. N2a cells subjected to serum deprivation and oxidative stress showed less cell death when miR-181a was reduced and increased death when miR-181a increased; protection was associated with increased Bcl-2 protein. In contrast, transfected primary neurons did not show altered levels of cell death when miR-181a levels changed. Naive male rats and rats stereotactically infused with miR-181a antagomir or control were subjected to forebrain ischemia and cornus ammonis (CA)1 neuronal survival and protein levels were assessed. Forebrain ischemia increased miR-181a expression and decreased Bcl-2 protein in the hippocampal CA1 region. miR-181a antagomir reduced miR-181a levels, reduced CA1 neuronal loss, increased Bcl-2 protein, and significantly prevented the decrease of glutamate transporter 1. Thus, miR-181a antagomir reduced evidence of astrocyte dysfunction and increased CA1 neuronal survival. miR-181a inhibition is thus a potential target in the setting of forebrain or global cerebral ischemia as well as focal ischemia.

scholarly journals Machine learning-based classification of mitochondrial morphology in primary neurons and brain

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Garrett M. Fogo ◽  
Anthony R. Anzell ◽  
Kathleen J. Maheras ◽  
Sarita Raghunayakula ◽  
Joseph M. Wider ◽  
...  
Keyword(s):  
Image Analysis ◽  
Cortical Neurons ◽  
Mitochondrial Dynamics ◽  
Automated Image Analysis ◽  
Mitochondrial Morphology ◽  
Analysis Pipeline ◽  
Genetic Ablation ◽  
Block Face

AbstractThe mitochondrial network continually undergoes events of fission and fusion. Under physiologic conditions, the network is in equilibrium and is characterized by the presence of both elongated and punctate mitochondria. However, this balanced, homeostatic mitochondrial profile can change morphologic distribution in response to various stressors. Therefore, it is imperative to develop a method that robustly measures mitochondrial morphology with high accuracy. Here, we developed a semi-automated image analysis pipeline for the quantitation of mitochondrial morphology for both in vitro and in vivo applications. The image analysis pipeline was generated and validated utilizing images of primary cortical neurons from transgenic mice, allowing genetic ablation of key components of mitochondrial dynamics. This analysis pipeline was further extended to evaluate mitochondrial morphology in vivo through immunolabeling of brain sections as well as serial block-face scanning electron microscopy. These data demonstrate a highly specific and sensitive method that accurately classifies distinct physiological and pathological mitochondrial morphologies. Furthermore, this workflow employs the use of readily available, free open-source software designed for high throughput image processing, segmentation, and analysis that is customizable to various biological models.

scholarly journals NIK promotes metabolic adaptation of glioblastoma cells to bioenergetic stress

2021 ◽  
Vol 12 (3) ◽  
Author(s):  
Michael L. Kamradt ◽  
Ji-Ung Jung ◽  
Kathryn M. Pflug ◽  
Dong W. Lee ◽  
Victor Fanniel ◽  
...  
Keyword(s):  
Stress Responses ◽  
Glucose Deprivation ◽  
Metabolic Adaptation ◽  
Mitochondrial Morphology ◽  
Atp Production ◽  
Tumor Microenvironments ◽  
Iκb Kinase ◽  
Critical Measure

AbstractCancers, including glioblastoma multiforme (GBM), undergo coordinated reprogramming of metabolic pathways that control glycolysis and oxidative phosphorylation (OXPHOS) to promote tumor growth in diverse tumor microenvironments. Adaptation to limited nutrient availability in the microenvironment is associated with remodeling of mitochondrial morphology and bioenergetic capacity. We recently demonstrated that NF-κB-inducing kinase (NIK) regulates mitochondrial morphology to promote GBM cell invasion. Here, we show that NIK is recruited to the outer membrane of dividing mitochondria with the master fission regulator, Dynamin-related protein1 (DRP1). Moreover, glucose deprivation-mediated metabolic shift to OXPHOS increases fission and mitochondrial localization of both NIK and DRP1. NIK deficiency results in decreased mitochondrial respiration, ATP production, and spare respiratory capacity (SRC), a critical measure of mitochondrial fitness. Although IκB kinase α and β (IKKα/β) and NIK are required for OXPHOS in high glucose media, only NIK is required to increase SRC under glucose deprivation. Consistent with an IKK-independent role for NIK in regulating metabolism, we show that NIK phosphorylates DRP1-S616 in vitro and in vivo. Notably, a constitutively active DRP1-S616E mutant rescues oxidative metabolism, invasiveness, and tumorigenic potential in NIK−/− cells without inducing IKK. Thus, we establish that NIK is critical for bioenergetic stress responses to promote GBM cell pathogenesis independently of IKK. Our data suggest that targeting NIK may be used to exploit metabolic vulnerabilities and improve therapeutic strategies for GBM.

scholarly journals Comparative analysis of the bioenergetics of human adenocarcinoma Caco-2 cell line and postoperative tissue samples from colorectal cancer patients

2018 ◽  
Vol 96 (6) ◽  
pp. 808-817 ◽  
Author(s):  
Lyudmila Ounpuu ◽  
Laura Truu ◽  
Igor Shevchuk ◽  
Vladimir Chekulayev ◽  
Aleksandr Klepinin ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Cell Line ◽  
Respiratory Chain ◽  
Growth Conditions ◽  
Control Analysis ◽  
Respiratory Chain Complexes ◽  
Colon Tissue ◽  
Tissue Samples

The aim of this work was to explore the key bioenergetic properties for mitochondrial respiration in the widely-used Caco-2 cell line and in human colorectal cancer (HCC) postoperational tissue samples. Oxygraphy and metabolic control analysis (MCA) were applied to estimate the function of oxidative phosphorylation in cultured Caco-2 cells and HCC tissue samples. The mitochondria of Caco-2 cells and HCC tissues displayed larger functional activity of respiratory complex (C)II compared with CI, whereas in normal colon tissue an inverse pattern in the ratio of CI to CII activity was observed. MCA showed that the respiration in Caco-2 and HCC tissue cells is regulated by different parts of electron transport chain. In HCC tissues, this control is performed essentially at the level of respiratory chain complexes I–IV, whereas in Caco-2 cells at the level of CIV (cytochrome c oxidase) and the ATP synthasome. The differences we found in the regulation of respiratory chain activity and glycose index could represent an adaptive response to distinct growth conditions; this highlights the importance of proper validation of results obtained from in-vitro models before their extrapolation to the more complex in-vivo systems.

scholarly journals Modulator of apoptosis-1 is a potential therapeutic target in acute ischemic injury

2018 ◽  
Vol 39 (12) ◽  
pp. 2406-2418 ◽  
Author(s):  
Su Jing Chan ◽  
Hui Zhao ◽  
Kazuhide Hayakawa ◽  
Chou Chai ◽  
Chong Teik Tan ◽  
...  
Keyword(s):  
Cortical Neurons ◽  
Infarct Volume ◽  
Neuronal Loss ◽  
Ischemic Injury ◽  
Glucose Deprivation ◽  
Artery Occlusion ◽  
In Vivo Models ◽  
The Brain

Modulator of apoptosis 1 (MOAP-1) is a Bax-associating protein highly enriched in the brain. In this study, we examined the role of MOAP-1 in promoting ischemic injuries following a stroke by investigating the consequences of MOAP-1 overexpression or deficiency in in vitro and in vivo models of ischemic stroke. MOAP-1 overexpressing SH-SY5Y cells showed significantly lower cell viability following oxygen and glucose deprivation (OGD) treatment when compared to control cells. Consistently, MOAP-1−/− primary cortical neurons were observed to be more resistant against OGD treatment than the MOAP-1+/+ primary neurons. In the mouse transient middle cerebral artery occlusion (tMCAO) model, ischemia triggered MOAP-1/Bax association, suggested activation of the MOAP-1-dependent apoptotic cascade. MOAP-1−/− mice were found to exhibit reduced neuronal loss and smaller infarct volume 24 h after tMCAO when compared to MOAP-1+/+ mice. Correspondingly, MOAP-1−/− mice also showed better integrity of neurological functions as demonstrated by their performance in the rotarod test. Therefore, both in vitro and in vivo data presented strongly support the conclusion that MOAP-1 is an important apoptotic modulator in ischemic injury. These results may suggest that a reduction of MOAP-1 function in the brain could be a potential therapeutic approach in the treatment of acute stroke.

LncRNA PVT1 Mediated by ZFP36L2 Regulates Myocardial Ischemia/Reperfusion Injury and Attenuates Mitochondrial Fusion and Fission via Activating miR-21-5p/MARCH5 Axis

2020 ◽  
Author(s):  
Weifeng Huang ◽  
Qin Tan ◽  
Yong Guo ◽  
Yongmei Cao ◽  
Jiawei Shang ◽  
...  
Keyword(s):  
Zinc Finger Protein ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Mitochondrial Fission ◽  
Tumor Biology ◽  
Luciferase Reporter ◽  
Mitochondrial Morphology ◽  
Mrna Levels

Abstract BackgroundAmong several leading cardiovascular disorders, ischemia-reperfusion (I/R) injury causes severe manifestations including acute heart failure, inflammation, and systemic dysfunction. Recently, there has been increasing evidence suggesting that alterations in mitochondrial morphology play a role in the prognoses of cardiac disorders. Long non-coding RNAs (lncRNAs) form major regulatory networks to modify gene transcription and translation. While several roles of lncRNAs have been explored in cancer and tumor biology, their implications on mitochondrial morphology and functions remain to be elucidated. MethodsThe functional roles of ZFP36L2 and lncRNA PVT1 were determined by a series of cardiomyocyte hypoxia/ reoxygenation (H/R) in vitro and myocardial I/R injury in vivo experiments. Quantitative Reverse transcription-polymerase chain reaction (qRT-PCR) and western blot analysis were used to detect the mRNA levels of ZFP36L2 and mitochondrial fission and fusion markers in the myocardial tissues and cardiomyocyte. Cardiac function was determined by immunohistochemistry, H&E, Masson’s staining and echocardiogram. Ultrastructural analysis of mitochondrial fission was performed using transmission electron microscopy (TEM). The mechanistic model of PVT1 with ZFP36L2 and miR-21-5p with MARCH5 was detected by subcellular fraction, RNA pull down, FISH, and luciferase reporter assays.ResultsIn this study, we report a novel regulatory axis involving lncRNA PVT1, microRNA miR-21-5p, and E3 ubiquitin ligase MARCH5, which alters mitochondrial morphology during myocardial I/R injury. Using an in vivo I/R injury mouse model and in vitro cardiomyocyte H/R model, we observed that zinc finger protein ZFP36L2 directly associated with PVT1 and altered mitochondrial fission and fusion. PVT1 also interacted with miR-21-5p and suppressed its expression and activity. Furthermore, we identified MARCH5 as a modifier of miR-21-5p, and expression of MARCH5 and its effect on mitochondrial fission and fusion were directly proportional to PVT1 expression during H/R injury. ConclusionsOur findings demonstrated that manipulation of PVT1-miR-21-5p-MARCH5-mediated mitochondrial fission and fusion via ZFP36L2 may be a novel therapeutic approach to regulate myocardial I/R injury.

scholarly journals Caffeine Modulates Cadmium-Induced Oxidative Stress, Neuroinflammation, and Cognitive Impairments by Regulating Nrf-2/HO-1 In Vivo and In Vitro

2019 ◽  
Vol 8 (5) ◽  
pp. 680 ◽  
Author(s):  
Amjad Khan ◽  
Muhammad Ikram ◽  
Tahir Muhammad ◽  
Junsung Park ◽  
Myeong Ok Kim
Keyword(s):  
Oxidative Stress ◽  
Cell Lines ◽  
Cognitive Deficits ◽  
Calcium Binding ◽  
Neuronal Loss ◽  
Treated Group ◽  
Nuclear Factor ◽  
Acute And Chronic Exposure

Cadmium (Cd), a nonbiodegradable heavy metal and one of the most neurotoxic environmental and industrial pollutants, promotes disturbances in major organs and tissues following both acute and chronic exposure. In this study, we assessed the neuroprotective potential of caffeine (30 mg/kg) against Cd (5 mg/kg)-induced oxidative stress-mediated neuroinflammation, neuronal apoptosis, and cognitive deficits in male C57BL/6N mice in vivo and in HT-22 and BV-2 cell lines in vitro. Interestingly, our findings indicate that caffeine markedly reduced reactive oxygen species (ROS) and lipid peroxidation (LPO) levels and enhanced the expression of nuclear factor-2 erythroid-2 (Nrf-2) and hemeoxygenase-1 (HO-1), which act as endogenous antioxidant regulators. Also, 8-dihydro-8-oxoguanine (8-OXO-G) expression was considerably reduced in the caffeine-treated group as compared to the Cd-treated group. Similarly, caffeine ameliorated Cd-mediated glial activation by reducing the expression of glial fibrillary acidic protein (GFAP), ionized calcium-binding adapter molecule 1 (Iba-1), and other inflammatory mediators in the cortical and hippocampal regions of the mouse brain. Moreover, caffeine markedly attenuated Cd-induced neuronal loss, synaptic dysfunction, and learning and cognitive deficits. Of note, nuclear factor-2 erythroid-2 (Nrf-2) gene silencing and nuclear factor-κB (NF-κB) inhibition studies revealed that caffeine exerted neuroprotection via regulation of Nrf-2- and NF-κB-dependent mechanisms in the HT-22 and BV-2 cell lines, respectively. On the whole, these findings reveal that caffeine rescues Cd-induced oxidative stress-mediated neuroinflammation, neurodegeneration, and memory impairment. The present study suggests that caffeine might be a potential antioxidant and neuroprotective agent against Cd-induced neurodegeneration.

scholarly journals Antisense Proline-Arginine RAN Dipeptides Linked to C9ORF72-ALS/FTD Form Toxic Nuclear Aggregates that Initiate In Vitro and In Vivo Neuronal Death

Neuron ◽  
2014 ◽  
Vol 84 (6) ◽  
pp. 1213-1225 ◽  
Author(s):  
Xinmei Wen ◽  
Wenzhi Tan ◽  
Thomas Westergard ◽  
Karthik Krishnamurthy ◽  
Shashirekha S. Markandaiah ◽  
...  
Keyword(s):  
Neuronal Death
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