MITOL deletion in the brain impairs mitochondrial structure and ER tethering leading to oxidative stress

Mitochondrial abnormalities are associated with developmental disorders, although a causal relationship remains largely unknown. Here, we report that increased oxidative stress in neurons by deletion of mitochondrial ubiquitin ligase MITOL causes a potential neuroinflammation including aberrant astrogliosis and microglial activation, indicating that mitochondrial abnormalities might confer a risk for inflammatory diseases in brain such as psychiatric disorders. A role of MITOL in both mitochondrial dynamics and ER-mitochondria tethering prompted us to characterize three-dimensional structures of mitochondria in vivo. In MITOL-deficient neurons, we observed a significant reduction in the ER-mitochondria contact sites, which might lead to perturbation of phospholipids transfer, consequently reduce cardiolipin biogenesis. We also found that branched large mitochondria disappeared by deletion of MITOL. These morphological abnormalities of mitochondria resulted in enhanced oxidative stress in brain, which led to astrogliosis and microglial activation partly causing abnormal behavior. In conclusion, the reduced ER-mitochondria tethering and excessive mitochondrial fission may trigger neuroinflammation through oxidative stress.

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Abstract 392: Angiotensin II TypeI Receptor-mediated Mitochondrial Fission and Suppression of Mitophagy Play Crucial Role in Vascular Senescence and Arteriosclerosis

Circulation Research ◽

10.1161/res.127.suppl_1.392 ◽

2020 ◽

Vol 127 (Suppl_1) ◽

Author(s):

Yoshihiro Uchikado ◽

Yoshiyuki Ikeda ◽

Yuichi Sasaki ◽

Yuichi Akasaki ◽

Mitsuru Ohishi

Keyword(s):

Oxidative Stress ◽

Angiotensin Ii ◽

Mitochondrial Dysfunction ◽

Cellular Senescence ◽

Mitochondrial Dynamics ◽

Mitochondrial Fission ◽

Double Knockout ◽

Apoe Ko ◽

Vascular Senescence

Introduction: Metabolic stress including oxidized low density lipoprotein (ox-LDL) cause mitochondrial dysfunction and evoke vascular senescence and atherosclerosis. Mitochondria are highly dynamic organelles that undergo quality control by mitochondrial dynamics and mitophagy. This study aims to clarify whether and how mitochondrial dynamics and mitophagy are involved in the etiology of vascular senescence and arteriosclerosis. Methods: VSMC were stimulated by ox-LDL. We also conducted in vivo experiment using C57BL6 (WT), apolipoprotein E (ApoE) deficient and the double knockout of ApoE mice and Angiotensin II Type1 Receptor (AT1R). Results: Treatment of ox-LDL forced mitochondria to fission through activation of Drp1, induced mitochondrial dysfunction and oxidative stress, and developed cellular senescence. Inhibition of either Drp1, AT1R, MAPK retarded them, suggesting that mitochondrial fission plays key roles to develop premature cellular senescence and is modulated by AT1R/MAPK signal.Administration of ox-LDL decreased the number of mitophagy assessed by electron microscopy and immunohistochemistry of LAMP2 and TOMM20. AT1R signal inhibition increased mitophagy which was not affected by Atg7 knockdown, whereas it was decreased by either Rab9 or Ulk1 knockdown. Immunohistochemistry showed Rab9 dots were co-localized to TOMM20 and LAMP2, whereas LC3 dots were not, suggesting that AT1R signal induces mitophagy through Rab9-dependent alternative autophagy. The degree of vascular senescence was higher, the number of fused mitochondria and mitochondrial function were lower and mitochondrial oxidative stress was higher in ApoE KO than those in WT. DKO attenuated these adverse effect of ApoE KO. Conclusion: AT1R regulates vascular senescence and arteriosclerosis via induction of mitochondrial fission and inhibition of mitophagy.

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Aberrant mitochondrial fission in neurons induced by protein kinase Cδ under oxidative stress conditions in vivo

Molecular Biology of the Cell ◽

10.1091/mbc.e10-06-0551 ◽

2011 ◽

Vol 22 (2) ◽

pp. 256-265 ◽

Cited By ~ 162

Author(s):

Xin Qi ◽

Marie-Helene Disatnik ◽

Ning Shen ◽

Raymond A. Sobel ◽

Daria Mochly-Rosen

Keyword(s):

Oxidative Stress ◽

Protein Kinase ◽

Mitochondrial Dynamics ◽

Mitochondrial Fission ◽

Neuronal Cell Death ◽

Neuronal Cell ◽

Mitochondrial Fragmentation ◽

Neurological Pathology ◽

Protein Kinase Cδ

Neuronal cell death in a number of neurological disorders is associated with aberrant mitochondrial dynamics and mitochondrial degeneration. However, the triggers for this mitochondrial dysregulation are not known. Here we show excessive mitochondrial fission and mitochondrial structural disarray in brains of hypertensive rats with hypertension-induced brain injury (encephalopathy). We found that activation of protein kinase Cδ (PKCδ) induced aberrant mitochondrial fragmentation and impaired mitochondrial function in cultured SH-SY5Y neuronal cells and in this rat model of hypertension-induced encephalopathy. Immunoprecipitation studies indicate that PKCδ binds Drp1, a major mitochondrial fission protein, and phosphorylates Drp1 at Ser 579, thus increasing mitochondrial fragmentation. Further, we found that Drp1 Ser 579 phosphorylation by PKCδ is associated with Drp1 translocation to the mitochondria under oxidative stress. Importantly, inhibition of PKCδ, using a selective PKCδ peptide inhibitor (δV1-1), reduced mitochondrial fission and fragmentation and conferred neuronal protection in vivo and in culture. Our study suggests that PKCδ activation dysregulates the mitochondrial fission machinery and induces aberrant mitochondrial fission, thus contributing to neurological pathology.

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Mitochondrial Transplantation Modulates Inflammation and Apoptosis, Alleviating Tendinopathy Both In Vivo and In Vitro

Antioxidants ◽

10.3390/antiox10050696 ◽

2021 ◽

Vol 10 (5) ◽

pp. 696

Author(s):

Ji Min Lee ◽

Jung Wook Hwang ◽

Mi Jin Kim ◽

Sang Youn Jung ◽

Kyung-Soo Kim ◽

...

Keyword(s):

Oxidative Stress ◽

Mitochondrial Dynamics ◽

Mitochondrial Fission ◽

Tendon Healing ◽

Nuclear Factor Κb ◽

Therapeutic Effects ◽

Matrix Metalloproteinase 1 ◽

Anti Inflammatory

Tendinopathy is a common musculoskeletal condition causing pain and dysfunction. Conventional treatment and surgical procedures for tendinopathy are insufficient; accordingly, recent research has focused on tendon-healing regenerative approaches. Tendon injuries usually occur in the hypoxic critical zone, characterized by increased oxidative stress and mitochondrial dysfunction; thus, exogenous intact mitochondria may be therapeutic. We aimed to assess whether mitochondrial transplantation could induce anti-inflammatory activity and modulate the metabolic state of a tendinopathy model. Exogenous mitochondria were successfully delivered into damaged tenocytes by centrifugation. Levels of Tenomodulin and Collagen I in damaged tenocytes were restored with reductions in nuclear factor-κB and matrix metalloproteinase 1. The dysregulation of oxidative stress and mitochondrial membrane potential was attenuated by mitochondrial transplantation. Activated mitochondrial fission markers, such as fission 1 and dynamin-related protein 1, were dose-dependently downregulated. Apoptosis signaling pathway proteins were restored to the pre-damage levels. Similar changes were observed in a collagenase injection-induced rat model of tendinopathy. Exogenous mitochondria incorporated into the Achilles tendon reduced inflammatory and fission marker levels. Notably, collagen production was restored. Our results demonstrate the therapeutic effects of direct mitochondrial transplantation in tendinopathy. These effects may be explained by alterations in anti-inflammatory and apoptotic processes via changes in mitochondrial dynamics.

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Exploiting Anti-Inflammation Effects of Flavonoids in Chronic Inflammatory Diseases

Current Pharmaceutical Design ◽

10.2174/1381612826666200408101550 ◽

2020 ◽

Vol 26 (22) ◽

pp. 2610-2619 ◽

Cited By ~ 2

Author(s):

Tarique Hussain ◽

Ghulam Murtaza ◽

Huansheng Yang ◽

Muhammad S. Kalhoro ◽

Dildar H. Kalhoro

Keyword(s):

Oxidative Stress ◽

Chronic Diseases ◽

Inflammatory Diseases ◽

Therapeutic Option ◽

Cellular Level ◽

Antiinflammatory Drugs ◽

Suitable Alternative ◽

Chronic Inflammatory Diseases

Background: Inflammation is a complex response of the host defense system to different internal and external stimuli. It is believed that persistent inflammation may lead to chronic inflammatory diseases such as, inflammatory bowel disease, neurological and cardiovascular diseases. Oxidative stress is the main factor responsible for the augmentation of inflammation via various molecular pathways. Therefore, alleviating oxidative stress is effective a therapeutic option against chronic inflammatory diseases. Methods: This review article extends the knowledge of the regulatory mechanisms of flavonoids targeting inflammatory pathways in chronic diseases, which would be the best approach for the development of suitable therapeutic agents against chronic diseases. Results: Since the inflammatory response is initiated by numerous signaling molecules like NF-κB, MAPK, and Arachidonic acid pathways, their encountering function can be evaluated with the activation of Nrf2 pathway, a promising approach to inhibit/prevent chronic inflammatory diseases by flavonoids. Over the last few decades, flavonoids drew much attention as a potent alternative therapeutic agent. Recent clinical evidence has shown significant impacts of flavonoids on chronic diseases in different in-vivo and in-vitro models. Conclusion: Flavonoid compounds can interact with chronic inflammatory diseases at the cellular level and modulate the response of protein pathways. A promising approach is needed to overlook suitable alternative compounds providing more therapeutic efficacy and exerting fewer side effects than commercially available antiinflammatory drugs.

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Heme Oxygenase-1 Deficiency and Oxidative Stress: A Review of 9 Independent Human Cases and Animal Models

International Journal of Molecular Sciences ◽

10.3390/ijms22041514 ◽

2021 ◽

Vol 22 (4) ◽

pp. 1514 ◽

Cited By ~ 1

Author(s):

Akihiro Yachie

Keyword(s):

Oxidative Stress ◽

Animal Models ◽

Heme Oxygenase ◽

Inflammatory Diseases ◽

Cell Types ◽

Pharmacological Intervention ◽

Heme Oxygenase 1 ◽

Inflammatory Reactions

Since Yachie et al. reported the first description of human heme oxygenase (HO)-1 deficiency more than 20 years ago, few additional human cases have been reported in the literature. A detailed analysis of the first human case of HO-1 deficiency revealed that HO-1 is involved in the protection of multiple tissues and organs from oxidative stress and excessive inflammatory reactions, through the release of multiple molecules with anti-oxidative stress and anti-inflammatory functions. HO-1 production is induced in vivo within selected cell types, including renal tubular epithelium, hepatic Kupffer cells, vascular endothelium, and monocytes/macrophages, suggesting that HO-1 plays critical roles in these cells. In vivo and in vitro studies have indicated that impaired HO-1 production results in progressive monocyte dysfunction, unregulated macrophage activation and endothelial cell dysfunction, leading to catastrophic systemic inflammatory response syndrome. Data from reported human cases of HO-1 deficiency and numerous studies using animal models suggest that HO-1 plays critical roles in various clinical settings involving excessive oxidative stress and inflammation. In this regard, therapy to induce HO-1 production by pharmacological intervention represents a promising novel strategy to control inflammatory diseases.

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Syntaxin-17-Dependent Mitochondrial Dynamics is Essential for Protection Against Oxidative-Stress-Induced Apoptosis

Antioxidants ◽

10.3390/antiox8110522 ◽

2019 ◽

Vol 8 (11) ◽

pp. 522 ◽

Cited By ~ 4

Author(s):

Wang ◽

Xiao ◽

Huang ◽

Liu

Keyword(s):

Oxidative Stress ◽

Mitochondrial Dynamics ◽

Mitochondrial Fission ◽

Autophagic Flux ◽

Wild Type ◽

Dual Roles ◽

Defective Mutant ◽

U2os Cells ◽

Induced Apoptosis

In this study, cell death induced by the oxidant tert-butylhydroperoxide (tBH) was observed in U2OS cells; this phenotype was rescued by Syntaxin 17 (STX17) knockout (KO) but the mechanism is unknown. STX17 plays dual roles in autophagosome–lysosome fusion and mitochondrial fission. However, the contribution of the two functions of STX17 to apoptosis has not been extensively studied. Here, we sought to dissect the dual roles of STX17 in oxidative-stress-induced apoptosis by taking advantage of STX17 knockout cells and an autophagosome–lysosome fusion defective mutant of STX17. We generated STX17 knockout U2OS cells using the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system and the STX17 knockout cells were reconstituted with wild-type STX17 and its autophagosome–lysosome fusion defective mutant. Autophagy was assessed by autophagic flux assay, Monomer red fluorescent protein (mRFP)–GFP–LC3 assay and protease protection assay. Golgi, endoplasmic reticulum (ER)/ER–Golgi intermediate compartment (ERGIC) and mitochondrial dynamics were examined by staining the different indicator proteins. Apoptosis was evaluated by caspase cleavage assay. The general reactive oxygen species (ROS) were detected by flow cytometry. In STX17 complete knockout cells, sealed autophagosomes were efficiently formed but their fusion with lysosomes was less defective. The fusion defect was rescued by wild-type STX17 but not the autophagosome–lysosome fusion defective mutant. No obvious defects in Golgi, ERGIC or ER dynamics were observed. Mitochondria were significantly elongated, supporting a role of STX17 in mitochondria fission and the elongation caused by STX17 KO was reversed by the autophagosome–lysosome fusion defective mutant. The clearance of protein aggregation was compromised, correlating with the autophagy defect but not with mitochondrial dynamics. This study revealed a mixed role of STX17 in autophagy, mitochondrial dynamics and oxidative stress response. STX17 knockout cells were highly resistant to oxidative stress, largely due to the function of STX17 in mitochondrial fission rather than autophagy.

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Non-alcoholic fatty liver disease in mice with hepatocyte-specific deletion of mitochondrial fission factor

Diabetologia ◽

10.1007/s00125-021-05488-2 ◽

2021 ◽

Author(s):

Yukina Takeichi ◽

Takashi Miyazawa ◽

Shohei Sakamoto ◽

Yuki Hanada ◽

Lixiang Wang ◽

...

Keyword(s):

Er Stress ◽

Mitochondrial Dynamics ◽

Mitochondrial Fission ◽

Primary Hepatocytes ◽

Alcoholic Fatty Liver ◽

Expression Of Genes ◽

Specific Deletion

Abstract Aims/hypothesis Mitochondria are highly dynamic organelles continuously undergoing fission and fusion, referred to as mitochondrial dynamics, to adapt to nutritional demands. Evidence suggests that impaired mitochondrial dynamics leads to metabolic abnormalities such as non-alcoholic steatohepatitis (NASH) phenotypes. However, how mitochondrial dynamics are involved in the development of NASH is poorly understood. This study aimed to elucidate the role of mitochondrial fission factor (MFF) in the development of NASH. Methods We created mice with hepatocyte-specific deletion of MFF (MffLiKO). MffLiKO mice fed normal chow diet (NCD) or high-fat diet (HFD) were evaluated for metabolic variables and their livers were examined by histological analysis. To elucidate the mechanism of development of NASH, we examined the expression of genes related to endoplasmic reticulum (ER) stress and lipid metabolism, and the secretion of triacylglycerol (TG) using the liver and primary hepatocytes isolated from MffLiKO and control mice. Results MffLiKO mice showed aberrant mitochondrial morphologies with no obvious NASH phenotypes during NCD, while they developed full-blown NASH phenotypes in response to HFD. Expression of genes related to ER stress was markedly upregulated in the liver from MffLiKO mice. In addition, expression of genes related to hepatic TG secretion was downregulated, with reduced hepatic TG secretion in MffLiKO mice in vivo and in primary cultures of MFF-deficient hepatocytes in vitro. Furthermore, thapsigargin-induced ER stress suppressed TG secretion in primary hepatocytes isolated from control mice. Conclusions/interpretation We demonstrated that ablation of MFF in liver provoked ER stress and reduced hepatic TG secretion in vivo and in vitro. Moreover, MffLiKO mice were more susceptible to HFD-induced NASH phenotype than control mice, partly because of ER stress-induced apoptosis of hepatocytes and suppression of TG secretion from hepatocytes. This study provides evidence for the role of mitochondrial fission in the development of NASH. Graphical abstract

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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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Mitochondrial pathogenic mechanism and degradation in optineurin E50K mutation-mediated retinal ganglion cell degeneration

Scientific Reports ◽

10.1038/srep33830 ◽

2016 ◽

Vol 6 (1) ◽

Cited By ~ 32

Author(s):

Myoung Sup Shim ◽

Yuji Takihara ◽

Keun-Young Kim ◽

Takeshi Iwata ◽

Beatrice Y. J. T. Yue ◽

...

Keyword(s):

Oxidative Stress ◽

Ganglion Cell ◽

Retinal Ganglion Cell ◽

Open Angle Glaucoma ◽

Mitochondrial Fission ◽

Retinal Ganglion ◽

Cell Degeneration ◽

Transport Dynamics

Abstract Mutations in optineurin (OPTN) are linked to the pathology of primary open angle glaucoma (POAG) and amyotrophic lateral sclerosis. Emerging evidence indicates that OPTN mutation is involved in accumulation of damaged mitochondria and defective mitophagy. Nevertheless, the role played by an OPTN E50K mutation in the pathogenic mitochondrial mechanism that underlies retinal ganglion cell (RGC) degeneration in POAG remains unknown. We show here that E50K expression induces mitochondrial fission-mediated mitochondrial degradation and mitophagy in the axons of the glial lamina of aged E50K−tg mice in vivo. While E50K activates the Bax pathway and oxidative stress, and triggers dynamics alteration-mediated mitochondrial degradation and mitophagy in RGC somas in vitro, it does not affect transport dynamics and fission of mitochondria in RGC axons in vitro. These results strongly suggest that E50K is associated with mitochondrial dysfunction in RGC degeneration in synergy with environmental factors such as aging and/or oxidative stress.

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PIM Kinases Alter Mitochondrial Dynamics and Chemosensitivity in Lung Cancer

10.1101/863811 ◽

2019 ◽

Author(s):

Shailender S. Chauhan ◽

Rachel K. Toth ◽

Corbin C. Jensen ◽

Andrea L. Casillas ◽

David F. Kashatus ◽

...

Keyword(s):

Lung Cancer ◽

Mitochondrial Dynamics ◽

Nsclc Patient ◽

Mitochondrial Fission ◽

Inverse Correlation ◽

Mitochondrial Superoxide ◽

Pim Kinases ◽

Response To Chemotherapy

AbstractResistance to chemotherapy represents a major obstacle to the successful treatment of non-small cell lung cancer (NSCLC). The goal of this study was to determine how PIM kinases impact mitochondrial dynamics, ROS production, and response to chemotherapy in lung cancer. Live cell imaging and microscopy were used to determine the effect of PIM loss or inhibition on mitochondrial phenotype and ROS. Inhibition of PIM kinases caused excessive mitochondrial fission and significant upregulation of mitochondrial superoxide, increasing intercellular ROS. Mechanistically, we define a signaling axis linking PIM1 to Drp1 and mitochondrial fission in lung cancer. PIM inhibition significantly increased the protein levels and mitochondrial localization of Drp1, causing marked fragmentation of mitochondria. An inverse correlation between PIM1 and Drp1 was confirmed in NSCLC patient samples. Inhibition of PIM sensitized NSCLC to chemotherapy and produced a synergistic anti-tumor response in vitro and in vivo. Immunohistochemistry and transmission electron microscopy verified that PIM inhibitors promote mitochondrial fission and apoptosis in vivo. These data improve our knowledge about how PIM1 regulates mitochondria and provide justification for combining PIM inhibition with chemotherapy in NSCLC.

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