bims-mikwok Biomed News
on Mitochondrial quality control
Issue of 2022–10–09
eleven papers selected by
Avinash N. Mukkala, University of Toronto
  1. Primary astrocytic mitochondrial transplantation ameliorates ischemic stroke.
  2. Defective Mitochondrial Quality Control during Dengue Infection Contributes to Disease Pathogenesis.
  3. RHOA, a small G-protein, signals to mitophagy through regulation of PINK1 protein stability and protects cardiomyocytes against ischemia.
  4. Ischemic Preconditioning and Postconditioning Protect the Heart by Preserving the Mitochondrial Network.
  5. Mechanisms and significance of tissue-specific MICU regulation of the mitochondrial calcium uniporter complex.
  6. Nuclear-embedded mitochondrial DNA sequences in 66,083 human genomes.
  7. Mesoscale structure-function relationships in mitochondrial transcriptional condensates.
  8. Omentin1 ameliorates myocardial ischemia-induced heart failure via SIRT3/FOXO3a-dependent mitochondrial dynamical homeostasis and mitophagy.
  9. Preparation of mitochondrial damage-associated molecular patterns from mouse liver tissue.
  10. Cyclophilin D-induced mitochondrial impairment confers axonal injury after intracerebral hemorrhage in mice.
  11. Two independent respiratory chains adapt OXPHOS performance to glycolytic switch.
  1. BMB Rep. 2022 Oct 05. pii: 5674. [Epub ahead of print]
    Primary astrocytic mitochondrial transplantation ameliorates ischemic stroke.
    Eun-Hye Lee, Minkyung Kim, Seung Hwan Kim, Chun-Hyung Kim, Minhyung Lee, Chang-Hwan Park.
      Mitochondria are important organelles that regulate adenosine triphosphate (ATP) production, intracellular calcium buffering, cell survival, and apoptosis. They play therapeutic roles in injured cells via transcellular transfer through extracellular vesicles, gap junctions, and tunneling nanotubes. Astrocytes can secrete numerous factors known to promote neuronal survival, synaptic formation, and plasticity. Recent studies have demonstrated that astrocytes can transfer mitochondria to damaged neurons to enhance their viability and recovery. In this study, we observed that treatment with mitochondria isolated from rat primary astrocytes enhanced cell viability and ameliorated hydrogen peroxide-damaged neurons. Interestingly, isolated astrocytic mitochondria increased the number of cells under damaged neuronal conditions, but not under normal conditions, although the mitochondrial transfer efficiency did not differ between the two conditions. This effect was also observed after transplanting astrocytic mitochondria in a rat middle cerebral artery occlusion model. These findings suggest that mitochondria transfer therapy can be used to treat acute ischemic stroke and other diseases.
  2. J Virol. 2022 Oct 05. e0082822
    Defective Mitochondrial Quality Control during Dengue Infection Contributes to Disease Pathogenesis.
    Bharati Singh, Kiran Avula, Shamim Akhtar Sufi, Nahid Parwin, Sayani Das, Mohd Faraz Alam, Subhashish Samantaray, Leelakrishna Bankapalli, Alankrita Rani, Kokavalla Poornima, Biswajita Prusty, Tareni P Mallick, Shubham K Shaw, Hiren Dodia, Shobhitendu Kabi, Trupti T Pagad, Sriprasad Mohanty, Gulam Hussain Syed.
      Mitochondrial fitness is governed by mitochondrial quality control pathways comprising mitochondrial dynamics and mitochondrial-selective autophagy (mitophagy). Disruption of these processes has been implicated in many human diseases, including viral infections. Here, we report a comprehensive analysis of the effect of dengue infection on host mitochondrial homeostasis and its significance in dengue disease pathogenesis. Despite severe mitochondrial stress and injury, we observed that the pathways of mitochondrial quality control and mitochondrial biogenesis are paradoxically downregulated in dengue-infected human liver cells. This leads to the disruption of mitochondrial homeostasis and the onset of cellular injury and necrotic death in the infected cells. Interestingly, dengue promotes global autophagy but selectively disrupts mitochondrial-selective autophagy (mitophagy). Dengue downregulates the expression of PINK1 and Parkin, the two major proteins involved in tagging the damaged mitochondria for elimination through mitophagy. Mitophagy flux assays also suggest that Parkin-independent pathways of mitophagy are also inactive during dengue infection. Dengue infection also disrupts mitochondrial biogenesis by downregulating the master regulators PPARγ and PGC1α. Dengue-infected cells release mitochondrial damage-associated molecular patterns (mtDAMPs) such as mitochondrial DNA into the cytosol and extracellular milieu. Furthermore, the challenge of naive immune cells with culture supernatants from dengue-infected liver cells was sufficient to trigger proinflammatory signaling. In correlation with our in vitro observations, dengue patients have high levels of cell-free mitochondrial DNA in their blood in proportion to the degree of thrombocytopenia. Overall, our study shows how defective mitochondrial homeostasis in dengue-infected liver cells can drive dengue disease pathogenesis. IMPORTANCE Many viruses target host cell mitochondria to create a microenvironment conducive to viral dissemination. Dengue virus also exploits host cell mitochondria to facilitate its viral life cycle. Dengue infection of liver cells leads to severe mitochondrial injury and inhibition of proteins that regulate mitochondrial quality control and biogenesis, thereby disrupting mitochondrial homeostasis. A defect in mitochondrial quality control leads to the accumulation of damaged mitochondria and promotes cellular injury. This leads to the release of mitochondrial damage-associated molecular patterns (mt-DAMPs) into the cell cytoplasm and extracellular milieu. These mt-DAMPs activate the naive immune cells and trigger proinflammatory signaling, leading to the release of cytokines and chemokines, which may trigger systemic inflammation and contribute to dengue disease pathogenesis. In correlation with this, we observed high levels of cell-free mitochondrial DNA in dengue patient blood. This study provides insight into how the disruption of mitochondrial quality control in dengue-infected cells can trigger inflammation and drive dengue disease pathogenesis.
    Keywords:  autophagy; dengue virus; inflammation; mitochondria; mitochondrial homeostasis; mitochondrial quality control; mitophagy; mt-DNA; necrosis
    DOI:  https://doi.org/10.1128/jvi.00828-22
  3. Autophagy. 2022 Oct 06.
    RHOA, a small G-protein, signals to mitophagy through regulation of PINK1 protein stability and protects cardiomyocytes against ischemia.
    Michelle Tu, Shigeki Miyamoto.
      RHOA (ras homolog family member A) is a small G-protein that regulates a range of cellular processes including cell growth and survival. RHOA is a proximal downstream effector of G protein-coupled receptor coupling to GNA12/Gα12-GNA13/Gα13 proteins, and is activated in response to stretch and oxidative stress, functioning as a stress-response molecule. It has been demonstrated that RHOA signaling provides cardioprotection through inhibition of mitochondrial death pathways. Mitochondrial integrity is preserved not only by inhibition of mitochondrial death pathways but also by mitochondrial quality control mechanisms including mitophagy. One of the most well-established mechanisms of mitophagy is the mitochondrial membrane depolarization-dependent PINK1-PRKN/Parkin pathway. However, depolarization of the mitochondrial membrane potential is a late-stage event that occurs just before cell death, and additional intracellular mechanisms that enhance the PINK1-PRKN pathway have not been fully determined. We recently discovered that RHOA activation engages a unique mechanism to regulate PINK1 protein stability without inducing mitochondrial membrane depolarization, leading to increased mitophagy and protection against ischemia in cardiomyocytes. Our results suggest regulation of RHOA signaling as a potential strategy to enhance protective mitophagy against stress without compromising mitochondrial functions.
    Keywords:  Cardiomyocytes; PINK1, RHOA; ischemia; mitophagy, Parkin
    DOI:  https://doi.org/10.1080/15548627.2022.2132707
  4. Biomed Res Int. 2022 ;2022 6889278
    Ischemic Preconditioning and Postconditioning Protect the Heart by Preserving the Mitochondrial Network.
    Nur Izzah Ismail, Nathaly Anto Michel, Khairunnisa Katwadi, Mim-Mim Lim, To-Kiu Chan, Attaur Rahman, Dachun Xu, Sang-Ging Ong, Derek J Hausenloy, Sang-Bing Ong.
       Background: Mitochondria fuse to form elongated networks which are more tolerable to stress and injury. Ischemic pre- and postconditioning (IPC and IPost, respectively) are established cardioprotective strategies in the preclinical setting. Whether IPC and IPost modulates mitochondrial morphology is unknown. We hypothesize that the protective effects of IPC and IPost may be conferred via preservation of mitochondrial network.
    Methods: IPC and IPost were applied to the H9c2 rat myoblast cells, isolated adult primary murine cardiomyocytes, and the Langendorff-isolated perfused rat hearts. The effects of IPC and IPost on cardiac cell death following ischemia-reperfusion injury (IRI), mitochondrial morphology, and gene expression of mitochondrial-shaping proteins were investigated.
    Results: IPC and IPost successfully reduced cardiac cell death and myocardial infarct size. IPC and IPost maintained the mitochondrial network in both H9c2 and isolated adult primary murine cardiomyocytes. 2D-length measurement of the 3 mitochondrial subpopulations showed that IPC and IPost significantly increased the length of interfibrillar mitochondria (IFM). Gene expression of the pro-fusion protein, Mfn1, was significantly increased by IPC, while the pro-fission protein, Drp1, was significantly reduced by IPost in the H9c2 cells. In the primary cardiomyocytes, gene expression of both Mfn1 and Mfn2 were significantly upregulated by IPC and IPost, while Drp1 was significantly downregulated by IPost. In the Langendorff-isolated perfused heart, gene expression of Drp1 was significantly downregulated by both IPC and IPost.
    Conclusion: IPC and IPost-mediated upregulation of pro-fusion proteins (Mfn1 and Mfn2) and downregulation of pro-fission (Drp1) promote maintenance of the interconnected mitochondrial network, ultimately conferring cardioprotection against IRI.
    DOI:  https://doi.org/10.1155/2022/6889278
  5. Mol Cell. 2022 Oct 06. pii: S1097-2765(22)00895-4. [Epub ahead of print]82(19): 3661-3676.e8
    Mechanisms and significance of tissue-specific MICU regulation of the mitochondrial calcium uniporter complex.
    Chen-Wei Tsai, Madison X Rodriguez, Anna M Van Keuren, Charles B Phillips, Hannah M Shushunov, Jessica E Lee, Anastacia M Garcia, Amrut V Ambardekar, Joseph C Cleveland, Julie A Reisz, Catherine Proenza, Kathryn C Chatfield, Ming-Feng Tsai.
      Mitochondrial Ca2+ uptake, mediated by the mitochondrial Ca2+ uniporter, regulates oxidative phosphorylation, apoptosis, and intracellular Ca2+ signaling. Previous studies suggest that non-neuronal uniporters are exclusively regulated by a MICU1-MICU2 heterodimer. Here, we show that skeletal-muscle and kidney uniporters also complex with a MICU1-MICU1 homodimer and that human/mouse cardiac uniporters are largely devoid of MICUs. Cells employ protein-importation machineries to fine-tune the relative abundance of MICU1 homo- and heterodimers and utilize a conserved MICU intersubunit disulfide to protect properly assembled dimers from proteolysis by YME1L1. Using the MICU1 homodimer or removing MICU1 allows mitochondria to more readily take up Ca2+ so that cells can produce more ATP in response to intracellular Ca2+ transients. However, the trade-off is elevated ROS, impaired basal metabolism, and higher susceptibility to death. These results provide mechanistic insights into how tissues can manipulate mitochondrial Ca2+ uptake properties to support their unique physiological functions.
    Keywords:  calcium channels; cardiac pathophysiology; cellular metabolism; intracellular calcium signaling; membrane-transport mechanisms; mitochondrial physiology; mitochondrial proteases; organellar channels; protein complexes
    DOI:  https://doi.org/10.1016/j.molcel.2022.09.006
  6. Nature. 2022 Oct 05.
    Nuclear-embedded mitochondrial DNA sequences in 66,083 human genomes.
    Wei Wei, Katherine R Schon, Greg Elgar, Andrea Orioli, Melanie Tanguy, Adam Giess, Marc Tischkowitz, Mark J Caulfield, Patrick F Chinnery.
      DNA transfer from cytoplasmic organelles to the cell nucleus is a legacy of the endosymbiotic event-the majority of nuclear-mitochondrial segments (NUMTs) are thought to be ancient, preceding human speciation1-3. Here we analyse whole-genome sequences from 66,083 people-including 12,509 people with cancer-and demonstrate the ongoing transfer of mitochondrial DNA into the nucleus, contributing to a complex NUMT landscape. More than 99% of individuals had at least one of 1,637 different NUMTs, with 1 in 8 individuals having an ultra-rare NUMT that is present in less than 0.1% of the population. More than 90% of the extant NUMTs that we evaluated inserted into the nuclear genome after humans diverged from apes. Once embedded, the sequences were no longer under the evolutionary constraint seen within the mitochondrion, and NUMT-specific mutations had a different mutational signature to mitochondrial DNA. De novo NUMTs were observed in the germline once in every 104 births and once in every 103 cancers. NUMTs preferentially involved non-coding mitochondrial DNA, linking transcription and replication to their origin, with nuclear insertion involving multiple mechanisms including double-strand break repair associated with PR domain zinc-finger protein 9 (PRDM9) binding. The frequency of tumour-specific NUMTs differed between cancers, including a probably causal insertion in a myxoid liposarcoma. We found evidence of selection against NUMTs on the basis of size and genomic location, shaping a highly heterogenous and dynamic human NUMT landscape.
    DOI:  https://doi.org/10.1038/s41586-022-05288-7
  7. Proc Natl Acad Sci U S A. 2022 Oct 11. 119(41): e2207303119
    Mesoscale structure-function relationships in mitochondrial transcriptional condensates.
    Marina Feric, Azadeh Sarfallah, Furqan Dar, Dmitry Temiakov, Rohit V Pappu, Tom Misteli.
      In live cells, phase separation is thought to organize macromolecules into membraneless structures known as biomolecular condensates. Here, we reconstituted transcription in condensates from purified mitochondrial components using optimized in vitro reaction conditions to probe the structure-function relationships of biomolecular condensates. We find that the core components of the mt-transcription machinery form multiphasic, viscoelastic condensates in vitro. Strikingly, the rates of condensate-mediated transcription are substantially lower than in solution. The condensate-mediated decrease in transcriptional rates is associated with the formation of vesicle-like structures that are driven by the production and accumulation of RNA during transcription. The generation of RNA alters the global phase behavior and organization of transcription components within condensates. Coarse-grained simulations of mesoscale structures at equilibrium show that the components stably assemble into multiphasic condensates and that the vesicles formed in vitro are the result of dynamical arrest. Overall, our findings illustrate the complex phase behavior of transcribing, multicomponent condensates, and they highlight the intimate, bidirectional interplay of structure and function in transcriptional condensates.
    Keywords:  biomolecular condensates; mitochondrial genome; phase separation; transcription; vesicles
    DOI:  https://doi.org/10.1073/pnas.2207303119
  8. J Transl Med. 2022 Oct 04. 20(1): 447
    Omentin1 ameliorates myocardial ischemia-induced heart failure via SIRT3/FOXO3a-dependent mitochondrial dynamical homeostasis and mitophagy.
    Jingui Hu, Tao Liu, Fei Fu, Zekun Cui, Qiong Lai, Yuanyuan Zhang, Boyang Yu, Fuming Liu, Junping Kou, Fang Li.
       BACKGROUND: Adipose tissue-derived adipokines are involved in various crosstalk between adipose tissue and other organs. Omentin1, a novel adipokine, exerts vital roles in the maintenance of body metabolism, insulin resistance and the like. However, the protective effect of omentin1 in myocardial ischemia (MI)-induced heart failure (HF) and its specific mechanism remains unclear and to be elucidated.
    METHODS: The model of MI-induced HF mice and oxygen glucose deprivation (OGD)-injured cardiomyocytes were performed. Mice with overexpression of omentin1 were constructed by a fat-specific adeno-associated virus (AAV) vector system.
    RESULTS: We demonstrated that circulating omentin1 level diminished in HF patients compared with healthy subjects. Furthermore, the fat-specific overexpression of omentin1 ameliorated cardiac function, cardiac hypertrophy, infarct size and cardiac pathological features, and also enhanced SIRT3/FOXO3a signaling in HF mice. Additionally, administration with AAV-omentin1 increased mitochondrial fusion and decreased mitochondrial fission in HF mice, as evidenced by up-regulated expression of Mfn2 and OPA1, and downregulation of p-Drp1(Ser616). Then, it also promoted PINK1/Parkin-dependent mitophagy. Simultaneously, treatment with recombinant omentin1 strengthened OGD-injured cardiomyocyte viability, restrained LDH release, and enhanced the mitochondrial accumulation of SIRT3 and nucleus transduction of FOXO3a. Besides, omentin1 also ameliorated unbalanced mitochondrial fusion-fission dynamics and activated mitophagy, thereby, improving the damaged mitochondria morphology and controlling mitochondrial quality in OGD-injured cardiomyocytes. Interestingly, SIRT3 played an important role in the improvement effects of omentin1 on mitochondrial function, unbalanced mitochondrial fusion-fission dynamics and mitophagy.
    CONCLUSION: Omentin1 improves MI-induced HF and myocardial injury by maintaining mitochondrial dynamical homeostasis and activating mitophagy via upregulation of SIRT3/FOXO3a signaling. This study provides evidence for further application of omentin1 in cardiovascular diseases from the perspective of crosstalk between heart and adipose tissue.
    Keywords:  Heart failure; Heart-adipose crosstalk; Mitochondrial dynamical homeostasis; Mitophagy; Omentin1; Sirtuin 3
    DOI:  https://doi.org/10.1186/s12967-022-03642-x
  9. STAR Protoc. 2022 Sep 30. pii: S2666-1667(22)00618-9. [Epub ahead of print]3(4): 101738
    Preparation of mitochondrial damage-associated molecular patterns from mouse liver tissue.
    Lauren P Westhaver, Sarah Nersesian, Adam Nelson, Leah K MacLean, Emily B Carter, Jeanette E Boudreau.
      Mitochondrial damage-associated molecular patterns (mitoDAMPs) are released from cells dying uncontrolled, non-apoptotic deaths, usually secondary to disease or trauma. Here, we describe preparation of mitoDAMPs from mouse liver, but this protocol can be adapted for preparation of mitoDAMPs from other species and tissues. Tissues are dissociated and then processed to isolate mitochondria. Mitochondria are then sonicated and mitoDAMPs are collected by ultracentrifugation. This procedure produces μg quantities of mitoDAMPs and facilitates research to understand their impacts in health and disease. For complete details on the use and execution of this protocol, please refer to Westhaver et al. (2022).
    Keywords:  Cell Biology; Cell isolation; Cell separation/fractionation; Cell-based Assays; Immunology; Metabolomics
    DOI:  https://doi.org/10.1016/j.xpro.2022.101738
  10. Neural Regen Res. 2023 Apr;18(4): 849-855
    Cyclophilin D-induced mitochondrial impairment confers axonal injury after intracerebral hemorrhage in mice.
    Yang Yang, Kai-Yuan Zhang, Xue-Zhu Chen, Chuan-Yan Yang, Ju Wang, Xue-Jiao Lei, Yu-Lian Quan, Wei-Xiang Chen, Heng-Li Zhao, Li-Kun Yang, Yu-Hai Wang, Yu-Jie Chen, Hua Feng.
      The mitochondrial permeability transition pore is a nonspecific transmembrane channel. Inhibition of mitochondrial permeability transition pore opening has been shown to alleviate mitochondrial swelling, calcium overload, and axonal degeneration. Cyclophilin D is an important component of the mitochondrial permeability transition pore. Whether cyclophilin D participates in mitochondrial impairment and axonal injury after intracerebral hemorrhage is not clear. In this study, we established mouse models of intracerebral hemorrhage in vivo by injection of autologous blood and oxyhemoglobin into the striatum in Thy1-YFP mice, in which pyramidal neurons and axons express yellow fluorescent protein. We also simulated intracerebral hemorrhage in vitro in PC12 cells using oxyhemoglobin. We found that axonal degeneration in the early stage of intracerebral hemorrhage depended on mitochondrial swelling induced by cyclophilin D activation and mitochondrial permeability transition pore opening. We further investigated the mechanism underlying the role of cyclophilin D in mouse models and PC12 cell models of intracerebral hemorrhage. We found that both cyclosporin A inhibition and short hairpin RNA interference of cyclophilin D reduced mitochondrial permeability transition pore opening and mitochondrial injury. In addition, inhibition of cyclophilin D and mitochondrial permeability transition pore opening protected corticospinal tract integrity and alleviated motor dysfunction caused by intracerebral hemorrhage. Our findings suggest that cyclophilin D is used as a key mediator of axonal degeneration after intracerebral hemorrhage; inhibition of cyclophilin D expression can protect mitochondrial structure and function and further alleviate corticospinal tract injury and motor dysfunction after intracerebral hemorrhage. Our findings provide a therapeutic target for preventing axonal degeneration of white matter injury and subsequent functional impairment in central nervous diseases.
    Keywords:  axonal injury; corticospinal tract; cyclophilin D; cyclosporin A; intracerebral hemorrhage; mitochondrial impairment; mitochondrial permeability transition pore; motor dysfunction; retraction bulb; white matter
    DOI:  https://doi.org/10.4103/1673-5374.353495
  11. Cell Metab. 2022 Sep 28. pii: S1550-4131(22)00395-3. [Epub ahead of print]
    Two independent respiratory chains adapt OXPHOS performance to glycolytic switch.
    Erika Fernández-Vizarra, Sandra López-Calcerrada, Ana Sierra-Magro, Rafael Pérez-Pérez, Luke E Formosa, Daniella H Hock, María Illescas, Ana Peñas, Michele Brischigliaro, Shujing Ding, Ian M Fearnley, Charalampos Tzoulis, Robert D S Pitceathly, Joaquín Arenas, Miguel A Martín, David A Stroud, Massimo Zeviani, Michael T Ryan, Cristina Ugalde.
      The structural and functional organization of the mitochondrial respiratory chain (MRC) remains intensely debated. Here, we show the co-existence of two separate MRC organizations in human cells and postmitotic tissues, C-MRC and S-MRC, defined by the preferential expression of three COX7A subunit isoforms, COX7A1/2 and SCAFI (COX7A2L). COX7A isoforms promote the functional reorganization of distinct co-existing MRC structures to prevent metabolic exhaustion and MRC deficiency. Notably, prevalence of each MRC organization is reversibly regulated by the activation state of the pyruvate dehydrogenase complex (PDC). Under oxidative conditions, the C-MRC is bioenergetically more efficient, whereas the S-MRC preferentially maintains oxidative phosphorylation (OXPHOS) upon metabolic rewiring toward glycolysis. We show a link between the metabolic signatures converging at the PDC and the structural and functional organization of the MRC, challenging the widespread notion of the MRC as a single functional unit and concluding that its structural heterogeneity warrants optimal adaptation to metabolic function.
    Keywords:  COX7A1–2; SCAFI/COX7RP/COX7A2L; bioenergetics; glycolysis; metabolic switch; mitochondria; oxidative metabolism; pyruvate dehydrogenase; respiratory chain organizations; respiratory supercomplexes
    DOI:  https://doi.org/10.1016/j.cmet.2022.09.005
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