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Chen Z, Xu P, Wang X, Li Y, Yang J, Xia Y, Wang S, Liu H, Xu Z, Li Z. MSC-NPRA loop drives fatty acid oxidation to promote stemness and chemoresistance of gastric cancer. Cancer Lett 2023; 565:216235. [PMID: 37209945 DOI: 10.1016/j.canlet.2023.216235] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 05/10/2023] [Accepted: 05/16/2023] [Indexed: 05/22/2023]
Abstract
Cisplatin (CDDP)-based chemotherapy is the preferred treatment strategy for advanced stage gastric cancer (GC) patients. Despite the efficacy of chemotherapy, the development of chemoresistance negatively affects the prognosis of GC and the underlying mechanism remains poorly understood. Accumulated evidence suggests that mesenchymal stem cells (MSCs) play important roles in drug resistance. The chemoresistance and stemness of GC cells were observed by colony formation, CCK-8, sphere formation and flow cytometry assays. Cell lines and animal models were utilized to investigate related functions. Western blot, quantitative real-time PCR (qRT-PCR) and co-immunoprecipitation were used to explore related pathways. The results showed that MSCs improved the stemness and chemoresistance of GC cells and accounted for the poor prognosis of GC. Natriuretic peptide receptor A (NPRA) was upregulated in GC cells cocultured with MSCs and knockdown of NPRA reversed the MSC-induced stemness and chemoresistance. At the same time, MSCs could be recruited to GC by NPRA, which formed a loop. In addition, NPRA facilitated stemness and chemoresistance through fatty acid oxidation (FAO). Mechanistically, NPRA protected Mfn2 against protein degradation and promoted its mitochondrial localization, which consequently improved FAO. Furthermore, inhibition of FAO with etomoxir (ETX) attenuated MSC-induced CDDP resistance in vivo. In conclusion, MSC-induced NPRA promoted stemness and chemoresistance by upregulating Mfn2 and improving FAO. These findings help us understand the role of NPRA in the prognosis and chemotherapy of GC. NPRA may be a promising target to overcome chemoresistance.
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Affiliation(s)
- Zetian Chen
- Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, Jiangsu Province, China
| | - Penghui Xu
- Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, Jiangsu Province, China
| | - Xinghong Wang
- Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, Jiangsu Province, China
| | - Ying Li
- Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, Jiangsu Province, China
| | - Jing Yang
- Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, Jiangsu Province, China
| | - Yiwen Xia
- Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, Jiangsu Province, China
| | - Sen Wang
- Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, Jiangsu Province, China
| | - Hongda Liu
- Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, Jiangsu Province, China
| | - Zekuan Xu
- Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, Jiangsu Province, China; Collaborative Innovation Center for Cancer Personalized Medicine, Nanjing Medical University, Nanjing, Jiangsu Province, China; The Institute of Gastric Cancer, Nanjing Medical University, Nanjing, Jiangsu Province, China.
| | - Zheng Li
- Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, Jiangsu Province, China.
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Kumar M, Sharma S, Mazumder S. Role of UPR mt and mitochondrial dynamics in host immunity: it takes two to tango. Front Cell Infect Microbiol 2023; 13:1135203. [PMID: 37260703 PMCID: PMC10227438 DOI: 10.3389/fcimb.2023.1135203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Accepted: 04/24/2023] [Indexed: 06/02/2023] Open
Abstract
The immune system of a host contains a group of heterogeneous cells with the prime aim of restraining pathogenic infection and maintaining homeostasis. Recent reports have proved that the various subtypes of immune cells exploit distinct metabolic programs for their functioning. Mitochondria are central signaling organelles regulating a range of cellular activities including metabolic reprogramming and immune homeostasis which eventually decree the immunological fate of the host under pathogenic stress. Emerging evidence suggests that following bacterial infection, innate immune cells undergo profound metabolic switching to restrain and countervail the bacterial pathogens, promote inflammation and restore tissue homeostasis. On the other hand, bacterial pathogens affect mitochondrial structure and functions to evade host immunity and influence their intracellular survival. Mitochondria employ several mechanisms to overcome bacterial stress of which mitochondrial UPR (UPRmt) and mitochondrial dynamics are critical. This review discusses the latest advances in our understanding of the immune functions of mitochondria against bacterial infection, particularly the mechanisms of mitochondrial UPRmt and mitochondrial dynamics and their involvement in host immunity.
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Affiliation(s)
- Manmohan Kumar
- Immunobiology Laboratory, Department of Zoology, University of Delhi, Delhi, India
| | - Shagun Sharma
- Immunobiology Laboratory, Department of Zoology, University of Delhi, Delhi, India
| | - Shibnath Mazumder
- Immunobiology Laboratory, Department of Zoology, University of Delhi, Delhi, India
- Faculty of Life Sciences and Biotechnology, South Asian University, Delhi, India
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3
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Xu J, Shamul JG, Kwizera EA, He X. Recent Advancements in Mitochondria-Targeted Nanoparticle Drug Delivery for Cancer Therapy. NANOMATERIALS 2022; 12:nano12050743. [PMID: 35269231 PMCID: PMC8911864 DOI: 10.3390/nano12050743] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Revised: 02/11/2022] [Accepted: 02/16/2022] [Indexed: 02/01/2023]
Abstract
Mitochondria are critical subcellular organelles that produce most of the adenosine triphosphate (ATP) as the energy source for most eukaryotic cells. Moreover, recent findings show that mitochondria are not only the "powerhouse" inside cells, but also excellent targets for inducing cell death via apoptosis that is mitochondria-centered. For several decades, cancer nanotherapeutics have been designed to specifically target mitochondria with several targeting moieties, and cause mitochondrial dysfunction via photodynamic, photothermal, or/and chemo therapies. These strategies have been shown to augment the killing of cancer cells in a tumor while reducing damage to its surrounding healthy tissues. Furthermore, mitochondria-targeting nanotechnologies have been demonstrated to be highly efficacious compared to non-mitochondria-targeting platforms both in vitro and in vivo for cancer therapies. Moreover, mitochondria-targeting nanotechnologies have been intelligently designed and tailored to the hypoxic and slightly acidic tumor microenvironment for improved cancer therapies. Collectively, mitochondria-targeting may be a promising strategy for the engineering of nanoparticles for drug delivery to combat cancer.
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Affiliation(s)
- Jiangsheng Xu
- Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA; (J.X.); (J.G.S.); (E.A.K.)
| | - James G. Shamul
- Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA; (J.X.); (J.G.S.); (E.A.K.)
| | - Elyahb Allie Kwizera
- Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA; (J.X.); (J.G.S.); (E.A.K.)
| | - Xiaoming He
- Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA; (J.X.); (J.G.S.); (E.A.K.)
- Marlene and Stewart Greenebaum Comprehensive Cancer Center, University of Maryland, Baltimore, MD 21201, USA
- Correspondence:
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4
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Hu Y, Chen H, Zhang L, Lin X, Li X, Zhuang H, Fan H, Meng T, He Z, Huang H, Gong Q, Zhu D, Xu Y, He P, Li L, Feng D. The AMPK-MFN2 axis regulates MAM dynamics and autophagy induced by energy stresses. Autophagy 2020; 17:1142-1156. [PMID: 32249716 DOI: 10.1080/15548627.2020.1749490] [Citation(s) in RCA: 121] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Energy deprivation activates the cellular energy sensor AMP-activated protein kinase (AMPK), which in turn induces macroautophagy/autophagy. The mitochondrial-associated ER membrane (MAM) plays a key role in mitochondrial division and autophagy, and the mitochondrial fusion protein MFN2 (mitofusin 2) tethers the MAM, but the mechanism by which AMPK and MFN2 regulate autophagy in response to energy stress remains unclear. Here, we found that energy stress not only triggers mitochondrial fission and autophagy, but more importantly increases the number of MAMs, a process that requires AMPK. Interestingly, under energy stress, considerable amounts of AMPK translocate from cytosol to the MAM and the mitochondrion as mitochondrial fission occurs. Unexpectedly, AMPK interacts directly with MFN2. The autophagic ability of mouse embryonic fibroblasts (MEFs) lacking MFN2 (mfn2-/-) is significantly attenuated in response to energy stress as compared to wild-type MEFs (WT MEFs), while re-expression of MFN2 in mfn2-/- cells rescues the autophagy defects of these cells. The abundance of MAMs is also greatly reduced in MFN2-deficient cells. Functional experiments show that the oxygen consumption rate and the glycolytic function of cells lacking MFN2 but not MFN1 are obviously attenuated, and MFN2 is important for cell survival under energy stress. In conclusion, our study establishes the molecular link between the energy sensor AMPK and the MAM tether MFN2, and reveals the important role of AMPK and MFN2 in energy stress-induced autophagy and MAM dynamics.Abbreviations: ACTB, actin beta; AMPK, AMP-activated protein kinase; BECN1, beclin 1; CANX, calnexin; ER, endoplasmic reticulum; HRP, horseradish peroxidase; EM, electron microscopy; FL, full-length; KD, kinase dead, KO, knockout; MAb, monoclonal antibody; MAMs, mitochondria-associated membranes; MAP1LC3/LC3B, microtubule associated protein 1 light chain 3; MFN2, mitofusin 2; OPA1, OPA1 mitochondrial dynamin like GTPase; PAb, polyclonal antibody; PtdIns3K, class III phosphatidylinositol 3-kinase; PtdIns3P, phosphatidylinositol 3-phosphate; SD, standard deviation; TEM, transmission electron microscopy; TOMM20, translocase of outer mitochondrial membrane 20; ULK1, unc-51 like autophagy activating kinase 1; MEF, mouse embryonic fibroblast; WT, wildtype.
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Affiliation(s)
- Yongquan Hu
- Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, Affiliated Cancer Hospital & Institute of Guangzhou Medical University, School of Basic Medical Sciences, Guangzhou Medical University, 511436, Guangzhou, China.,State Key Laboratory of Respiratory Disease, Guangzhou Medical University, 511436, Guangzhou, China
| | - Hao Chen
- Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, Affiliated Cancer Hospital & Institute of Guangzhou Medical University, School of Basic Medical Sciences, Guangzhou Medical University, 511436, Guangzhou, China.,Institute of Neurology, Affiliated Hospital of Guangdong Medical University, Zhanjiang 524001, China
| | - Luying Zhang
- Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, Affiliated Cancer Hospital & Institute of Guangzhou Medical University, School of Basic Medical Sciences, Guangzhou Medical University, 511436, Guangzhou, China.,State Key Laboratory of Respiratory Disease, Guangzhou Medical University, 511436, Guangzhou, China
| | - Xiaoying Lin
- Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, Affiliated Cancer Hospital & Institute of Guangzhou Medical University, School of Basic Medical Sciences, Guangzhou Medical University, 511436, Guangzhou, China.,Institute of Neurology, Affiliated Hospital of Guangdong Medical University, Zhanjiang 524001, China
| | - Xia Li
- Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, Affiliated Cancer Hospital & Institute of Guangzhou Medical University, School of Basic Medical Sciences, Guangzhou Medical University, 511436, Guangzhou, China.,State Key Laboratory of Respiratory Disease, Guangzhou Medical University, 511436, Guangzhou, China
| | - Haixia Zhuang
- Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, Affiliated Cancer Hospital & Institute of Guangzhou Medical University, School of Basic Medical Sciences, Guangzhou Medical University, 511436, Guangzhou, China.,State Key Laboratory of Respiratory Disease, Guangzhou Medical University, 511436, Guangzhou, China
| | - Hualin Fan
- Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, School of Medicine, South China University of Technology, Guangzhou, China
| | - Tian Meng
- Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, Affiliated Cancer Hospital & Institute of Guangzhou Medical University, School of Basic Medical Sciences, Guangzhou Medical University, 511436, Guangzhou, China.,State Key Laboratory of Respiratory Disease, Guangzhou Medical University, 511436, Guangzhou, China
| | - Zhengjie He
- Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, Affiliated Cancer Hospital & Institute of Guangzhou Medical University, School of Basic Medical Sciences, Guangzhou Medical University, 511436, Guangzhou, China.,State Key Laboratory of Respiratory Disease, Guangzhou Medical University, 511436, Guangzhou, China
| | - Haofeng Huang
- Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, Affiliated Cancer Hospital & Institute of Guangzhou Medical University, School of Basic Medical Sciences, Guangzhou Medical University, 511436, Guangzhou, China.,Institute of Neurology, Affiliated Hospital of Guangdong Medical University, Zhanjiang 524001, China
| | - Qing Gong
- Department of Biochemistry and Molecular Biology, GMU-GIBH Joint School of Life Sciences, Guangzhou Medical University, Guangzhou 511436, People's Republic of China
| | - Dongxing Zhu
- Guangzhou Institute of Cardiovascular Diseases, the Second Affiliated Hospital, Key Laboratory of Cardiovascular Diseases, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou 511436, China
| | - Yiming Xu
- School of Basic Medical Sciences, The Sixth Affiliated Hospital of Guangzhou Medical University, Qingyuan People's Hospital, Guangzhou Medical University, Guangzhou, China
| | - Pengcheng He
- Department of Cardiology, Guangdong Cardiovascular Institute, Guangdong Provincial Key Laboratory of Coronary Heart Disease Prevention, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China
| | - Longxuan Li
- Department of Neurology, Gongli Hospital, Pudong New Area, Shanghai 219 Miaopu Road, Pudong New Area, Shanghai 200135, P. R. China
| | - Du Feng
- Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, Affiliated Cancer Hospital & Institute of Guangzhou Medical University, School of Basic Medical Sciences, Guangzhou Medical University, 511436, Guangzhou, China.,State Key Laboratory of Respiratory Disease, Guangzhou Medical University, 511436, Guangzhou, China
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5
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Sinha S, Renganathan A, Nagendra PB, Bhat V, Mathew BS, Rao MRS. AEBP1 down regulation induced cell death pathway depends on PTEN status of glioma cells. Sci Rep 2019; 9:14577. [PMID: 31601918 PMCID: PMC6787275 DOI: 10.1038/s41598-019-51068-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 09/20/2019] [Indexed: 02/06/2023] Open
Abstract
Glioblastoma (GBM) is the most common aggressive form of brain cancer with overall dismal prognosis (10–12 months) despite all current multimodal treatments. Previously we identified adipocyte enhancer binding protein 1 (AEBP1) as a differentially regulated gene in GBM. On probing the role of AEBP1 over expression in glioblastoma, we found that both cellular proliferation and survival were affected upon AEBP1 silencing in glioma cells, resulting in cell death. In the present study we report that the classical caspase pathway components are not activated in cell death induced by AEBP1 down regulation in PTEN-deficient (U87MG and U138MG) cells. PARP-1 was not cleaved but over-activated under AEBP1 down regulation which leads to the synthesis of PAR in the nucleus triggering the release of AIF from the mitochondria. Subsequently, AIF translocates to the nucleus along with MIF causing chromatinolysis. AEBP1 positively regulates PI3KinaseCβ by the binding to AE-1 binding element in the PI3KinaseCβ promoter. Loss of PI3KinaseCβ expression under AEBP1 depleted condition leads to excessive DNA damage and activation of PARP-1. Furthermore, over expression of PIK3CB (in trans) in U138MG cells prevents DNA damage in these AEBP1 depleted cells. On the contrary, AEBP1 down regulation induces caspase-dependent cell death in PTEN-proficient (LN18 and LN229) cells. Ectopic expression of wild-type PTEN in PTEN-deficient U138MG cells results in the activation of canonical caspase and Akt dependent cell death. Collectively, our findings define AEBP1 as a potential oncogenic driver in glioma, with potential implications for therapeutic intervention.
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Affiliation(s)
- Swati Sinha
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advance Scientific Research, Bangalore, Karnataka, 560064, India
| | - Arun Renganathan
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advance Scientific Research, Bangalore, Karnataka, 560064, India.,Department of Surgery, Washington University in St. Louis, St. Louis, MO, USA
| | - Prathima B Nagendra
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advance Scientific Research, Bangalore, Karnataka, 560064, India.,Gynaecology Oncology Group, School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia
| | - Vasudeva Bhat
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advance Scientific Research, Bangalore, Karnataka, 560064, India.,Department of Immunology, Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Brian Steve Mathew
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advance Scientific Research, Bangalore, Karnataka, 560064, India
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6
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Chen F, Ardalan M, Elfving B, Wegener G, Madsen TM, Nyengaard JR. Mitochondria Are Critical for BDNF-Mediated Synaptic and Vascular Plasticity of Hippocampus following Repeated Electroconvulsive Seizures. Int J Neuropsychopharmacol 2017; 21:291-304. [PMID: 29228215 PMCID: PMC5838811 DOI: 10.1093/ijnp/pyx115] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 12/05/2017] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Electroconvulsive therapy is a fast-acting and efficient treatment of depression used in the clinic. The underlying mechanism of its therapeutic effect is still unclear. However, recovery of synaptic connections and synaptic remodeling is thought to play a critical role for the clinical efficacy obtained from a rapid antidepressant response. Here, we investigated the relationship between synaptic changes and concomitant nonneuronal changes in microvasculature and mitochondria and its relationship to brain-derived neurotrophic factor level changes after repeated electroconvulsive seizures, an animal model of electroconvulsive therapy. METHODS Electroconvulsive seizures or sham treatment was given daily for 10 days to rats displaying a genetically driven phenotype modelling clinical depression: the Flinders Sensitive and Resistant Line rats. Stereological principles were employed to quantify numbers of synapses and mitochondria, and the length of microvessels in the hippocampus. The brain-derived neurotrophic factor protein levels were quantified with immunohistochemistry. RESULTS In untreated controls, a lower number of synapses and mitochondria was accompanied by shorter microvessels of the hippocampus in "depressive" phenotype (Flinders Sensitive Line) compared with the "nondepressed" phenotype (Flinders Resistant Line). Electroconvulsive seizure administration significantly increased the number of synapses and mitochondria, and length of microvessels both in Flinders Sensitive Line-electroconvulsive seizures and Flinders Resistant Line-electroconvulsive seizures rats. In addition, the amount of brain-derived neurotrophic factor protein was significantly increased in Flinders Sensitive Line and Flinders Resistant Line rats after electroconvulsive seizures. Furthermore, there was a significant positive correlation between brain-derived neurotrophic factor level and mitochondria/synapses. CONCLUSION Our results indicate that rapid and efficient therapeutic effect of electroconvulsive seizures may be related to synaptic plasticity, accompanied by brain-derived neurotrophic factor protein level elevation and mitochondrial and vascular support.
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Affiliation(s)
- Fenghua Chen
- Core Center for Molecular Morphology, Section for Stereology and Microscopy, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark,Correspondence: Fenghua Chen, MD, PhD, Department of Clinical Medicine, Translational Neuropsychiatry Unit, Skovagervej 2, building 14K, 0.15, 8240 Risskov, Denmark ()
| | - Maryam Ardalan
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Risskov, Denmark,Center of Excellence for Pharmaceutical Sciences, North-West University, Potchefstroom, South Africa,Department of Clinical Medicine, Center of Functionally Integrative Neuroscience, Aarhus University, Aarhus, Denmark
| | - Betina Elfving
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Risskov, Denmark
| | - Gregers Wegener
- AUGUST Centre, Department of Clinical Medicine, Aarhus University, Risskov, Denmark
| | | | - Jens R Nyengaard
- Core Center for Molecular Morphology, Section for Stereology and Microscopy, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark,Centre for Stochastic Geometry and Advanced Bioimaging, Aarhus University, Aarhus, Denmark
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7
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Mitochondrial protein p32/HAPB1/gC1qR/C1qbp is required for efficient respiratory syncytial virus production. Biochem Biophys Res Commun 2017; 489:460-465. [DOI: 10.1016/j.bbrc.2017.05.171] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 05/29/2017] [Indexed: 11/21/2022]
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8
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Wang L, Ishihara T, Ibayashi Y, Tatsushima K, Setoyama D, Hanada Y, Takeichi Y, Sakamoto S, Yokota S, Mihara K, Kang D, Ishihara N, Takayanagi R, Nomura M. Disruption of mitochondrial fission in the liver protects mice from diet-induced obesity and metabolic deterioration. Diabetologia 2015; 58:2371-80. [PMID: 26233250 DOI: 10.1007/s00125-015-3704-7] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2015] [Accepted: 07/01/2015] [Indexed: 02/01/2023]
Abstract
AIM/HYPOTHESIS Mitochondria and the endoplasmic reticulum (ER) physically interact by close structural juxtaposition, via the mitochondria-associated ER membrane. Inter-organelle communication between the ER and mitochondria has been shown to regulate energy metabolism and to be central to the modulation of various key processes such as ER stress. We aimed to clarify the role of mitochondrial fission in this communication. METHODS We generated mice lacking the mitochondrial fission protein dynamin-related protein 1 (DRP1) in the liver (Drp1LiKO mice). RESULTS Drp1LiKO mice showed decreased fat mass and were protected from high-fat diet (HFD)-induced obesity. Analysis of liver gene expression profiles demonstrated marked elevation of ER stress markers. In addition, we observed increased expression of the fibroblast growth factor 21 (FGF21) gene through induction of activating transcription factor 4, master regulator of the integrated stress response. CONCLUSIONS/INTERPRETATION Disruption of mitochondrial fission in the liver provoked ER stress, while inducing the expression of FGF21 to increase energy expenditure and protect against HFD-induced obesity.
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Affiliation(s)
- Lixiang Wang
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Science, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Takaya Ishihara
- Department of Protein Biochemistry, Institute of Life Science, Kurume University, Kurume, Japan
| | - Yuta Ibayashi
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Science, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Keita Tatsushima
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Science, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Daiki Setoyama
- Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Science, Kyushu University, Fukuoka, Japan
| | - Yuki Hanada
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Science, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Yukina Takeichi
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Science, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Shohei Sakamoto
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Science, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Sadaki Yokota
- Division of Functional Morphology, Faculty of Pharmaceutical Sciences, Nagasaki International University, Sasebo, Nagasaki, Japan
| | - Katsuyoshi Mihara
- Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, Fukuoka, Japan
| | - Dongchon Kang
- Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Science, Kyushu University, Fukuoka, Japan
| | - Naotada Ishihara
- Department of Protein Biochemistry, Institute of Life Science, Kurume University, Kurume, Japan
| | - Ryoichi Takayanagi
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Science, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Masatoshi Nomura
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Science, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka, 812-8582, Japan.
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9
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Sanderson TH, Raghunayakula S, Kumar R. Neuronal hypoxia disrupts mitochondrial fusion. Neuroscience 2015; 301:71-8. [PMID: 26049142 PMCID: PMC4504771 DOI: 10.1016/j.neuroscience.2015.05.078] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 05/07/2015] [Accepted: 05/29/2015] [Indexed: 01/04/2023]
Abstract
Brain ischemia/reperfusion injury results in death of vulnerable neurons and extensive brain damage. It is well known that mitochondrial release of cytochrome c (cyto c) is a hallmark of neuronal death, however the molecular events underlying this release are largely unknown. We tested the hypothesis that cyto c release is regulated by breakdown of the cristae architecture maintenance protein, optic atrophy 1 (OPA1), located in the inner mitochondrial membrane. We simulated ischemia/reperfusion in isolated primary rat neurons and interrogated OPA1 release from the mitochondria, OPA1 oligomeric breakdown, and concomitant dysfunction of mitochondrial dynamic state. We found that ischemia/reperfusion induces cyto c release and cell death that corresponds to multiple changes in OPA1, including: (i) translocation of the mitochondrial fusion protein OPA1 from the mitochondria to the cytosol, (ii) increase in the short isoform of OPA1, suggestive of proteolytic processing, (iii) breakdown of OPA1 oligomers in the mitochondria, and (iv) increased mitochondrial fission. Thus, we present novel evidence of a connection between release of cyto c from mitochondria and disruption of the mitochondrial fusion.
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Affiliation(s)
- T H Sanderson
- Department of Emergency Medicine, Wayne State University School of Medicine, 540 E. Canfield, Detroit, MI, USA; Cardiovascular Research Institute, Wayne State University School of Medicine, 421E. Canfield, Detroit, MI, USA
| | - S Raghunayakula
- Department of Emergency Medicine, Wayne State University School of Medicine, 540 E. Canfield, Detroit, MI, USA
| | - R Kumar
- Department of Emergency Medicine, Wayne State University School of Medicine, 540 E. Canfield, Detroit, MI, USA; Cardiovascular Research Institute, Wayne State University School of Medicine, 421E. Canfield, Detroit, MI, USA; Department of Physiology, Wayne State University School of Medicine, 540 E. Canfield, Detroit, MI, USA.
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10
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Sanderson TH, Raghunayakula S, Kumar R. Release of mitochondrial Opa1 following oxidative stress in HT22 cells. Mol Cell Neurosci 2015; 64:116-22. [PMID: 25579226 DOI: 10.1016/j.mcn.2014.12.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 11/07/2014] [Accepted: 12/22/2014] [Indexed: 12/01/2022] Open
Abstract
Cellular mechanisms involved in multiple neurodegenerative diseases converge on mitochondria to induce overproduction of reactive oxygen species, damage to mitochondria, and subsequent cytochrome c release. Little is currently known regarding the contribution mitochondrial dynamics play in cytochrome c release following oxidative stress in neurodegenerative disease. Here we induced oxidative stress in the HT22 cell line with glutamate and investigated key mediators of mitochondrial dynamics to determine the role this process may play in oxidative stress induced neuronal death. We report that glutamate treatment in HT22 cells induces increase in reactive oxygen species (ROS), release of the mitochondrial fusion protein Opa1 into the cytosol, with concomitant release of cytochrome c. Furthermore, following the glutamate treatment alterations in cell signaling coincide with mitochondrial fragmentation which culminates in significant cell death in HT22 cells. Finally, we report that treatment with the antioxidant tocopherol attenuates glutamate induced-ROS increase, release of mitochondrial Opa1 and cytochrome c, and prevents cell death.
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Affiliation(s)
- Thomas H Sanderson
- Department of Emergency Medicine, Wayne State University School of Medicine, 550 E. Canfield, Detroit, MI, USA; Cardiovascular Research Institute, Wayne State University School of Medicine, 540 E. Canfield, Detroit, MI, USA; Department of Physiology, Wayne State University School of Medicine, 550 E. Canfield, Detroit, MI, USA
| | - Sarita Raghunayakula
- Department of Emergency Medicine, Wayne State University School of Medicine, 550 E. Canfield, Detroit, MI, USA
| | - Rita Kumar
- Department of Emergency Medicine, Wayne State University School of Medicine, 550 E. Canfield, Detroit, MI, USA; Cardiovascular Research Institute, Wayne State University School of Medicine, 540 E. Canfield, Detroit, MI, USA; Department of Physiology, Wayne State University School of Medicine, 550 E. Canfield, Detroit, MI, USA.
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11
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Díaz-Carballo D, Gustmann S, Jastrow H, Acikelli AH, Dammann P, Klein J, Dembinski U, Bardenheuer W, Malak S, Araúzo-Bravo MJ, Schultheis B, Aldinger C, Strumberg D. Atypical cell populations associated with acquired resistance to cytostatics and cancer stem cell features: the role of mitochondria in nuclear encapsulation. DNA Cell Biol 2014; 33:749-74. [PMID: 25126674 DOI: 10.1089/dna.2014.2375] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Until recently, acquired resistance to cytostatics had mostly been attributed to biochemical mechanisms such as decreased intake and/or increased efflux of therapeutics, enhanced DNA repair, and altered activity or deregulation of target proteins. Although these mechanisms have been widely investigated, little is known about membrane barriers responsible for the chemical imperviousness of cell compartments and cellular segregation in cytostatic-treated tumors. In highly heterogeneous cross-resistant and radiorefractory cell populations selected by exposure to anticancer agents, we found a number of atypical recurrent cell types in (1) tumor cell cultures of different embryonic origins, (2) mouse xenografts, and (3) paraffin sections from patient tumors. Alongside morphologic peculiarities, these populations presented cancer stem cell markers, aberrant signaling pathways, and a set of deregulated miRNAs known to confer both stem-cell phenotypes and highly aggressive tumor behavior. The first type, named spiral cells, is marked by a spiral arrangement of nuclei. The second type, monastery cells, is characterized by prominent walls inside which daughter cells can be seen maturing amid a rich mitochondrial environment. The third type, called pregnant cells, is a giant cell with a syncytium-like morphology, a main nucleus, and many endoreplicative functional progeny cells. A rare fourth cell type identified in leukemia was christened shepherd cells, as it was always associated with clusters of smaller cells. Furthermore, a portion of resistant tumor cells displayed nuclear encapsulation via mitochondrial aggregation in the nuclear perimeter in response to cytostatic insults, probably conferring imperviousness to drugs and long periods of dormancy until nuclear eclosion takes place. This phenomenon was correlated with an increase in both intracellular and intercellular mitochondrial traffic as well as with the uptake of free extracellular mitochondria. All these cellular disorders could, in fact, be found in untreated tumor cells but were more pronounced in resistant entities, suggesting a natural mechanism of cell survival triggered by chemical injury, or a primitive strategy to ensure stemming, self-renewal, and differentiation under adverse conditions, a fact that may play a significant role in chemotherapy outcomes.
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Affiliation(s)
- David Díaz-Carballo
- 1 Institute of Molecular Oncology and Experimental Therapeutics, Marienhospital Herne, Ruhr University of Bochum Medical School , Herne, Germany
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12
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A new non-canonical pathway of Gα(q) protein regulating mitochondrial dynamics and bioenergetics. Cell Signal 2014; 26:1135-46. [PMID: 24444709 DOI: 10.1016/j.cellsig.2014.01.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 01/09/2014] [Indexed: 12/12/2022]
Abstract
Contrary to previous assumptions, G proteins do not permanently reside on the plasma membrane, but are constantly monitoring the cytoplasmic surfaces of the plasma membrane and endomembranes. Here, we report that the Gαq and Gα11 proteins locate at the mitochondria and play a role in a complex signaling pathway that regulates mitochondrial dynamics. Our results provide evidence for the presence of the heteromeric G protein (Gαq/11βγ) at the outer mitochondrial membrane and for Gαq at the inner membrane. Both localizations are necessary to maintain the proper equilibrium between fusion and fission; which is achieved by altering the activity of mitofusin proteins, Drp1, OPA1 and the membrane potential at both the outer and inner mitochondrial membranes. As a result of the absence of Gαq/11, there is a decrease in mitochondrial fusion rates and a decrease in overall respiratory capacity, ATP production and OXPHOS-dependent growth. These findings demonstrate that the presence of Gαq proteins at the mitochondria serves as a physiological function: stabilizing elongated mitochondria and regulating energy production in Drp1 and Opa1 dependent mechanisms. This thereby links organelle dynamics and physiology.
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13
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p32 protein levels are integral to mitochondrial and endoplasmic reticulum morphology, cell metabolism and survival. Biochem J 2013; 453:381-91. [PMID: 23692256 PMCID: PMC3727215 DOI: 10.1042/bj20121829] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
p32 [also known as HABP1 (hyaluronan-binding protein 1), gC1qR (receptor for globular head domains complement 1q) or C1qbp (complement 1q-binding protein)] has been shown previously to have both mitochondrial and non-mitochondrial localization and functions. In the present study, we show for the first time that endogenous p32 protein is a mitochondrial protein in HeLa cells under control and stress conditions. In defining the impact of altering p32 levels in these cells, we demonstrate that the overexpression of p32 increased mitochondrial fibrils. Conversely, siRNA-mediated p32 knockdown enhanced mitochondrial fragmentation accompanied by a loss of detectable levels of the mitochondrial fusion mediator proteins Mfn (mitofusin) 1 and Mfn2. More detailed ultrastructure analysis by transmission electron microscopy revealed aberrant mitochondrial structures with less and/or fragmented cristae and reduced mitochondrial matrix density as well as more punctate ER (endoplasmic reticulum) with noticeable dissociation of their ribosomes. The analysis of mitochondrial bioenergetics showed significantly reduced capacities in basal respiration and oxidative ATP turnover following p32 depletion. Furthermore, siRNA-mediated p32 knockdown resulted in differential stress-dependent effects on cell death, with enhanced cell death observed in the presence of hyperosmotic stress or cisplatin treatment, but decreased cell death in the presence of arsenite. Taken together, our studies highlight the critical contributions of the p32 protein to the morphology of mitochondria and ER under normal cellular conditions, as well as important roles of the p32 protein in cellular metabolism and various stress responses.
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14
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Eisner V, Csordás G, Hajnóczky G. Interactions between sarco-endoplasmic reticulum and mitochondria in cardiac and skeletal muscle - pivotal roles in Ca²⁺ and reactive oxygen species signaling. J Cell Sci 2013; 126:2965-78. [PMID: 23843617 DOI: 10.1242/jcs.093609] [Citation(s) in RCA: 156] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Mitochondria are strategically and dynamically positioned in the cell to spatially coordinate ATP production with energy needs and to allow the local exchange of material with other organelles. Interactions of mitochondria with the sarco-endoplasmic reticulum (SR/ER) have been receiving much attention owing to emerging evidence on the role these sites have in cell signaling, dynamics and biosynthetic pathways. One of the most important physiological and pathophysiological paradigms for SR/ER-mitochondria interactions is in cardiac and skeletal muscle. The contractile activity of these tissues has to be matched by mitochondrial ATP generation that is achieved, at least in part, by propagation of Ca(2+) signals from SR to mitochondria. However, the muscle has a highly ordered structure, providing only limited opportunity for mitochondrial dynamics and interorganellar interactions. This Commentary focuses on the latest advances in the structure, function and disease relevance of the communication between SR/ER and mitochondria in muscle. In particular, we discuss the recent demonstration of SR/ER-mitochondria tethers that are formed by multiple proteins, and local Ca(2+) transfer between SR/ER and mitochondria.
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Affiliation(s)
- Verónica Eisner
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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15
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Meyer JN, Leung MCK, Rooney JP, Sendoel A, Hengartner MO, Kisby GE, Bess AS. Mitochondria as a target of environmental toxicants. Toxicol Sci 2013; 134:1-17. [PMID: 23629515 PMCID: PMC3693132 DOI: 10.1093/toxsci/kft102] [Citation(s) in RCA: 345] [Impact Index Per Article: 31.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Enormous strides have recently been made in our understanding of the biology and pathobiology of mitochondria. Many diseases have been identified as caused by mitochondrial dysfunction, and many pharmaceuticals have been identified as previously unrecognized mitochondrial toxicants. A much smaller but growing literature indicates that mitochondria are also targeted by environmental pollutants. We briefly review the importance of mitochondrial function and maintenance for health based on the genetics of mitochondrial diseases and the toxicities resulting from pharmaceutical exposure. We then discuss how the principles of mitochondrial vulnerability illustrated by those fields might apply to environmental contaminants, with particular attention to factors that may modulate vulnerability including genetic differences, epigenetic interactions, tissue characteristics, and developmental stage. Finally, we review the literature related to environmental mitochondrial toxicants, with a particular focus on those toxicants that target mitochondrial DNA. We conclude that the fields of environmental toxicology and environmental health should focus more strongly on mitochondria.
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Affiliation(s)
- Joel N Meyer
- Nicholas School of the Environment, Duke University, Durham, NC, USA.
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16
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Chen F, Wegener G, Madsen TM, Nyengaard JR. Mitochondrial plasticity of the hippocampus in a genetic rat model of depression after antidepressant treatment. Synapse 2012; 67:127-34. [PMID: 23152197 DOI: 10.1002/syn.21622] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 10/29/2012] [Indexed: 12/28/2022]
Abstract
Depressive disorders and the treatment thereof have been associated with a number of neuroplastic events, such as neurogenesis and synaptic remodeling in discrete areas of the brain. The associations of these events in changes regarding the energy supply have not been investigated. Here, we investigated the changes in mitochondrial plasticity and its correlation to morphological alterations of neuroplasticity in the hippocampus, both associated with a depressive phenotype, and after treatment, with antidepressant imipramine. Design-based stereological methods were used to estimate the number and volume of mitochondria in CA1 of the hippocampus in two different strains of rats, the Sprague-Dawley (SD) and Flinders rats, which display a genetic susceptibility to depressive behavior, the Flinders-sensitive line (FSL) and their corresponding controls, the Flinders-resistant line (FRL). Results showed a significantly reduced number of mitochondria in CA1, which was significantly smaller in the untreated FSL saline group compared to the FRL group. However, the mean volume of mitochondria was significantly larger in the FSL saline group compared to the FRL saline group. Following treatment, the FSL imipramine group showed a significant increase in the number of mitochondria compared to the FSL saline group. Treatment with imipramine in the SD rats did not induce significant differences in the number of mitochondria. Our results indicate that depression may be related to impairments of mitochondrial plasticity in the hippocampus and antidepressant treatment may counteract with the structural impairments. Moreover, the changes in mitochondrial morphology and number are a consistent feature of neuroplasticity.
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Affiliation(s)
- Fenghua Chen
- Stereology and Electron Microscopy Laboratory, Centre for Stochastic Geometry and Advanced Bioimaging, Aarhus University Hospital, DK-8000 Aarhus C, Denmark.
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17
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Mitochondrial dynamics and bioenergetic dysfunction is associated with synaptic alterations in mutant SOD1 motor neurons. J Neurosci 2012; 32:229-42. [PMID: 22219285 DOI: 10.1523/jneurosci.1233-11.2012] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Mutations in Cu,Zn superoxide dismutase (SOD1) cause familial amyotrophic lateral sclerosis (FALS), a rapidly fatal motor neuron disease. Mutant SOD1 has pleiotropic toxic effects on motor neurons, among which mitochondrial dysfunction has been proposed as one of the contributing factors in motor neuron demise. Mitochondria are highly dynamic in neurons; they are constantly reshaped by fusion and move along neurites to localize at sites of high-energy utilization, such as synapses. The finding of abnormal mitochondria accumulation in neuromuscular junctions, where the SOD1-FALS degenerative process is though to initiate, suggests that impaired mitochondrial dynamics in motor neurons may be involved in pathogenesis. We addressed this hypothesis by live imaging microscopy of photo-switchable fluorescent mitoDendra in transgenic rat motor neurons expressing mutant or wild-type human SOD1. We demonstrate that mutant SOD1 motor neurons have impaired mitochondrial fusion in axons and cell bodies. Mitochondria also display selective impairment of retrograde axonal transport, with reduced frequency and velocity of movements. Fusion and transport defects are associated with smaller mitochondrial size, decreased mitochondrial density, and defective mitochondrial membrane potential. Furthermore, mislocalization of mitochondria at synapses among motor neurons, in vitro, correlates with abnormal synaptic number, structure, and function. Dynamics abnormalities are specific to mutant SOD1 motor neuron mitochondria, since they are absent in wild-type SOD1 motor neurons, they do not involve other organelles, and they are not found in cortical neurons. Together, these results suggest that impaired mitochondrial dynamics may contribute to the selective degeneration of motor neurons in SOD1-FALS.
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18
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The mitochondrial contact site complex, a determinant of mitochondrial architecture. EMBO J 2011; 30:4356-70. [PMID: 22009199 DOI: 10.1038/emboj.2011.379] [Citation(s) in RCA: 340] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 09/29/2011] [Indexed: 11/08/2022] Open
Abstract
Mitochondria are organelles with a complex architecture. They are bounded by an envelope consisting of the outer membrane and the inner boundary membrane (IBM). Narrow crista junctions (CJs) link the IBM to the cristae. OMs and IBMs are firmly connected by contact sites (CS). The molecular nature of the CS remained unknown. Using quantitative high-resolution mass spectrometry we identified a novel complex, the mitochondrial contact site (MICOS) complex, formed by a set of mitochondrial membrane proteins that is essential for the formation of CS. MICOS is preferentially located at the CJs. Upon loss of one of the MICOS subunits, CJs disappear completely or are impaired, showing that CJs require the presence of CS to form a superstructure that links the IBM to the cristae. Loss of MICOS subunits results in loss of respiratory competence and altered inheritance of mitochondrial DNA.
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Abstract
Mitochondria are derived from eubacteria; however, in most eukaryotes, novel mechanisms for the propagation of this organelle and its genome have evolved. This review focuses on what is currently known about the novel molecular machines that divide and fuse mitochondria.
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Affiliation(s)
- Suzanne Hoppins
- Section of Molecular and Cellular Biology, University of California, Davis, California 95616, USA.
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Abstract
Mitochondria cannot be made de novo but replicate by a mechanism of recruitment of new proteins, which are added to preexisting subcompartments. Although mitochondria have their own DNA, more than 98% of the total protein complement of the organelle is encoded by the nuclear genome. Mitochondrial biogenesis requires a coordination of expression of two genomes and therefore cross talk between the nucleus and mitochondria. In mammals, regulation of mitochondrial biogenesis and proliferation is influenced by external factors, such as nutrients, hormones, temperature, exercise, hypoxia, and aging. This complexity points to the existence of a coordinated and tightly regulated network connecting different pathways. Communications are also required for eliciting mitochondrial responses to specific stress pathways. This review covers the mechanisms of mitochondrial biogenesis and the way cells respond to external signals to maintain mitochondrial function and cellular homeostasis.
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Affiliation(s)
- Michael T Ryan
- Department of Biochemistry, La Trobe University, Melbourne 3086, Australia.
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