bims-mikwok Biomed News
on Mitochondrial quality control
Issue of 2021–05–02
eightteen papers selected by
Avinash N. Mukkala, University of Toronto
  1. Common Principles and Specific Mechanisms of Mitophagy from Yeast to Humans.
  2. The Role of Mitophagy in Pulmonary Sepsis.
  3. PINK1: A Bridge between Mitochondria and Parkinson's Disease.
  4. Motor proteins at the mitochondria-cytoskeleton interface.
  5. Mitochondrial calcium at the synapse.
  6. Mitochondrial N-Methyl-D-Aspartate Receptor Activation Enhances Bioenergetics by Calcium-Dependent and -Independent Mechanisms.
  7. Mitochondria Donation by Mesenchymal Stem Cells: Current Understanding and Mitochondria Transplantation Strategies.
  8. PINK1-mediated mitophagy maintains pluripotency through optineurin.
  9. Inhibition of mitochondrial translation suppresses glioblastoma stem cell growth.
  10. Modeling the Effects of Calcium Overload on Mitochondrial Ultrastructural Remodeling.
  11. Bcl-2 Family of Proteins in the Control of Mitochondrial Calcium Signalling: An Old Chap with New Roles.
  12. Human Mitoribosome Biogenesis and Its Emerging Links to Disease.
  13. Mitochondrial Transplantation Modulates Inflammation and Apoptosis, Alleviating Tendinopathy Both In Vivo and In Vitro.
  14. Mitophagy in Human Diseases.
  15. A Crucial Role of Mitochondrial Dynamics in Dehydration Resistance in Saccharomyces cerevisiae.
  16. Role of PGC-1α in the Mitochondrial NAD+ Pool in Metabolic Diseases.
  17. Cellular pyrimidine imbalance triggers mitochondrial DNA-dependent innate immunity.
  18. The Novel Role of PGC1α in Bone Metabolism.
  1. Int J Mol Sci. 2021 Apr 22. pii: 4363. [Epub ahead of print]22(9):
    Common Principles and Specific Mechanisms of Mitophagy from Yeast to Humans.
    Rajesh Kumar, Andreas S Reichert.
      Mitochondria are double membrane-bound organelles in eukaryotic cells essential to a variety of cellular functions including energy conversion and ATP production, iron-sulfur biogenesis, lipid and amino acid metabolism, and regulating apoptosis and stress responses. Mitochondrial dysfunction is mechanistically linked to several neurodegenerative diseases, cancer, and ageing. Excessive and dysfunctional/damaged mitochondria are degraded by selective autophagic pathways known as mitophagy. Both budding yeast and mammals use the well-conserved machinery of core autophagy-related genes (ATGs) to execute and regulate mitophagy. In mammalian cells, the PINK1-PARKIN mitophagy pathway is a well-studied pathway that senses dysfunctional mitochondria and marks them for degradation in the lysosome. PINK1-PARKIN mediated mitophagy relies on ubiquitin-binding mitophagy adaptors that are non-ATG proteins. Loss-of-function mutations in PINK1 and PARKIN are linked to Parkinson´s disease (PD) in humans, and defective mitophagy is proposed to be a main pathomechanism. Despite the common view that yeast cells lack PINK1- and PARKIN-homologs and that mitophagy in yeast is solely regulated by receptor-mediated mitophagy, some studies suggest that a ubiquitination-dependent mitophagy pathway also exists. Here, we will discuss shared mechanisms between mammals and yeast, how mitophagy in the latter is regulated in a ubiquitin-dependent and -independent manner, and why these pathways are essential for yeast cell survival and fitness under various physiological stress conditions.
    Keywords:  PARKIN; PINK1; autophagy; cancer; mitophagy; quality control; ubiquitin
    DOI:  https://doi.org/10.3390/ijms22094363
  2. Mitochondrion. 2021 Apr 21. pii: S1567-7249(21)00055-6. [Epub ahead of print]
    The Role of Mitophagy in Pulmonary Sepsis.
    Mohd Mohsin, Gulnaz Tabassum, Shaniya Ahmad, Shakir Ali, Mansoor Ali Syed.
      Sepsis is a systemic inflammatory disease with an unacceptably high mortality rate caused by an infection or trauma that involves both innate and adaptive immune systems. Inflammatory events activate different downstream pathways leading to tissue damage and ultimately multi-organ failure. Mitochondria are responsible for cellular energy, thermoregulation, metabolite biosynthesis, intracellular calcium regulation, and cell death. Damaged mitochondria induce the high Ca2+ influx through mitochondrial calcium uniporter (MCU). It also generates excessive Reactive oxygen species (ROS) and releases mtDNA into the cytoplasm, which causes induction of NLRP3 inflammasome and apoptosis. Mitophagy (Autophagy of damaged mitochondria) controls mitochondrial dynamics and function. It also maintains cellular homeostasis. This review is about how pulmonary sepsis affects the body. What is the aftermath of sepsis, and how mitophagy affects Acute Lung Injury and macrophage polarisation to overcome the damages.
    Keywords:  ALI; Intracellular calcium; Macrophage polarisation; Mitophagy; Oxidative stress; Pulmonary sepsis; Sepsis
    DOI:  https://doi.org/10.1016/j.mito.2021.04.009
  3. Life (Basel). 2021 Apr 21. pii: 371. [Epub ahead of print]11(5):
    PINK1: A Bridge between Mitochondria and Parkinson's Disease.
    Filipa Barroso Gonçalves, Vanessa Alexandra Morais.
      Mitochondria are known as highly dynamic organelles essential for energy production. Intriguingly, in the recent years, mitochondria have revealed the ability to maintain cell homeostasis and ultimately regulate cell fate. This regulation is achieved by evoking mitochondrial quality control pathways that are capable of sensing the overall status of the cellular environment. In a first instance, actions to maintain a robust pool of mitochondria take place; however, if unsuccessful, measures that lead to overall cell death occur. One of the central key players of these mitochondrial quality control pathways is PINK1 (PTEN-induce putative kinase), a mitochondrial targeted kinase. PINK1 is known to interact with several substrates to regulate mitochondrial functions, and not only is responsible for triggering mitochondrial clearance via mitophagy, but also participates in maintenance of mitochondrial functions and homeostasis, under healthy conditions. Moreover, PINK1 has been associated with the familial form of Parkinson's disease (PD). Growing evidence has strongly linked mitochondrial homeostasis to the central nervous system (CNS), a system that is replenished with high energy demanding long-lasting neuronal cells. Moreover, sporadic cases of PD have also revealed mitochondrial impairments. Thus, one could speculate that mitochondrial homeostasis is the common denominator in these two forms of the disease, and PINK1 may play a central role in maintaining mitochondrial homeostasis. In this review, we will discuss the role of PINK1 in the mitochondrial physiology and scrutinize its role in the cascade of PD pathology.
    Keywords:  PINK1; Parkinson’s disease; mitochondria homeostasis
    DOI:  https://doi.org/10.3390/life11050371
  4. J Cell Sci. 2021 Apr 01. pii: jcs226084. [Epub ahead of print]134(7):
    Motor proteins at the mitochondria-cytoskeleton interface.
    Antonina J Kruppa, Folma Buss.
      Mitochondria are multifunctional organelles that not only produce energy for the cell, but are also important for cell signalling, apoptosis and many biosynthetic pathways. In most cell types, they form highly dynamic networks that are constantly remodelled through fission and fusion events, repositioned by motor-dependent transport and degraded when they become dysfunctional. Motor proteins and their tracks are key regulators of mitochondrial homeostasis, and in this Review, we discuss the diverse functions of the three classes of motor proteins associated with mitochondria - the actin-based myosins, as well as the microtubule-based kinesins and dynein. In addition, Miro and TRAK proteins act as adaptors that link kinesin-1 and dynein, as well as myosin of class XIX (MYO19), to mitochondria and coordinate microtubule- and actin-based motor activities. Here, we highlight the roles of motor proteins and motor-linked track dynamics in the transporting and docking of mitochondria, and emphasize their adaptations in specialized cells. Finally, we discuss how motor-cargo complexes mediate changes in mitochondrial morphology through fission and fusion, and how they modulate the turnover of damaged organelles via quality control pathways, such as mitophagy. Understanding the importance of motor proteins for mitochondrial homeostasis will help to elucidate the molecular basis of a number of human diseases.
    Keywords:  Actin; Dynein; Kinesin; Microtubules; Mitochondria; Myosin
    DOI:  https://doi.org/10.1242/jcs.226084
  5. Mitochondrion. 2021 Apr 22. pii: S1567-7249(21)00052-0. [Epub ahead of print]
    Mitochondrial calcium at the synapse.
    Sayantan Datta, Manish Jaiswal.
      Mitochondria are dynamic organelles, which serve various purposes, including but not limited to the production of ATP and various metabolites, buffering ions, acting as a signaling hub, etc. In recent years, mitochondria are being seen as the central regulators of cellular growth, development, and death. Since neurons are highly specialized cells with a heavy metabolic demand, it is not surprising that neurons are one of the most mitochondria-rich cells in an animal. At synapses, mitochondrial function and dynamics is tightly regulated by synaptic calcium. Calcium influx during synaptic activity causes increased mitochondrial calcium influx leading to an increased ATP production as well as buffering of synaptic calcium. While increased ATP production is required during synaptic transmission, calcium buffering by mitochondria is crucial to prevent faulty neurotransmission and excitotoxicity. Interestingly, mitochondrial calcium also regulates the mobility of mitochondria within synapses causing mitochondria to halt at the synapse during synaptic transmission. In this review, we summarize the various roles of mitochondrial calcium at the synapse.
    Keywords:  LETM1; MCU; Mitochondrial Calcium Efflux; Mitochondrial Calcium Influx; NCLX; Synaptic Calcium; VDAC
    DOI:  https://doi.org/10.1016/j.mito.2021.04.006
  6. Mitochondrion. 2021 Apr 21. pii: S1567-7249(21)00057-X. [Epub ahead of print]
    Mitochondrial N-Methyl-D-Aspartate Receptor Activation Enhances Bioenergetics by Calcium-Dependent and -Independent Mechanisms.
    Amit S Korde, William F Maragos.
      Our laboratory has demonstrated that functional N-methyl-D-aspartate-like receptors are present on neuronal mitochondria (NMDAm). This novel site gates the influx of Ca2+ and causes a several-fold increase in ATP levels. Although elevations in ATP in other cell types have been linked to increases in mitochondrial Ca2+, it has not been established whether the same holds true for calcium uptake via NMDAm. In this study, we have investigated the effect of NMDAm activation on a variety of bioenergetic parameters. Our findings suggest that mitochondrial bioenergetics are not only modulated by NMDAm activation in a Ca2+-dependent but also in a Ca2+-independent manner.
    Keywords:  ATP; Bioenergetics; Calcium; Mitochondria; N-methyl-D-aspartate; Respiration
    DOI:  https://doi.org/10.1016/j.mito.2021.04.011
  7. Front Cell Dev Biol. 2021 ;9 653322
    Mitochondria Donation by Mesenchymal Stem Cells: Current Understanding and Mitochondria Transplantation Strategies.
    Marina O Gomzikova, Victoria James, Albert A Rizvanov.
      The phenomenon of mitochondria donation is found in various tissues of humans and animals and is attracting increasing attention. To date, numerous studies have described the transfer of mitochondria from stem cells to injured cells, leading to increased ATP production, restoration of mitochondria function, and rescue of recipient cells from apoptosis. Mitochondria transplantation is considered as a novel therapeutic approach for the treatment of mitochondrial diseases and mitochondrial function deficiency. Mitochondrial dysfunction affects cells with high energy needs such as neural, skeletal muscle, heart, and liver cells and plays a crucial role in type 2 diabetes, as well as Parkinson's, Alzheimer's diseases, ischemia, stroke, cancer, and age-related disorders. In this review, we summarize recent findings in the field of mitochondria donation and mechanism of mitochondria transfer between cells. We review the existing clinical trials and discuss advantages and disadvantages of mitochondrial transplantation strategies based on the injection of stem cells, isolated functional mitochondria, or EVs containing mitochondria.
    Keywords:  cell fusion; extracellular vesicles; isolated mitochondria; mitochondria donation; mitochondria transplantation; tunneling nanotubes
    DOI:  https://doi.org/10.3389/fcell.2021.653322
  8. Cell Prolif. 2021 May 01. e13034
    PINK1-mediated mitophagy maintains pluripotency through optineurin.
    Chaoqun Wang, Kun Liu, Jiani Cao, Liang Wang, Qian Zhao, Zheng Li, Honghai Zhang, Quan Chen, Tongbiao Zhao.
       OBJECTIVES: Dysfunction of autophagy results in accumulation of depolarized mitochondria and breakdown of self-renewal and pluripotency in ESCs. However, the regulators that control how mitochondria are degraded by autophagy for pluripotency regulation remains largely unknown. This study aims to dissect the molecular mechanisms that regulate mitochondrial homeostasis for pluripotency regulation in mouse ESCs.
    MATERIALS AND METHODS: Parkin+/+ and parkin-/- ESCs were established from E3.5 blastocysts of parkin+/- x parkin+/- mating mice. The pink1-/- , optn-/- and ndp52-/- ESCs were generated by CRISPR-Cas9. shRNAs were used for function loss assay of target genes. Mito-Keima, ROS and ATP detection were used to investigate the mitophagy and mitochondrial function. Western blot, Q-PCR, AP staining and teratoma formation assay were performed to evaluate the PSC stemness.
    RESULTS: PINK1 or OPTN depletion impairs the degradation of dysfunctional mitochondria during reprogramming, and reduces the reprogramming efficiency and quality. In ESCs, PINK1 or OPTN deficiency leads to accumulation of dysfunctional mitochondria and compromised pluripotency. The defective mitochondrial homeostasis and pluripotency in pink1-/- ESCs can be compensated by gain expression of phosphomimetic Ubiquitin (Ub-S65D) together with WT or a constitutively active phosphomimetic OPTN mutant (S187D, S476D, S517D), rather than constitutively inactive OPTN (S187A, S476A, S517A) or a Ub-binding dead OPTN mutant (D477N).
    CONCLUSIONS: The mitophagy receptor OPTN guards ESC mitochondrial homeostasis and pluripotency by scavenging damaged mitochondria through TBK1-activated OPTN binding of PINK1-phosphorylated Ubiquitin.
    Keywords:  OPTN; PINK1; embryonic stem cells; mitochondria; mitophagy; reprogramming
    DOI:  https://doi.org/10.1111/cpr.13034
  9. Cell Rep. 2021 Apr 27. pii: S2211-1247(21)00338-7. [Epub ahead of print]35(4): 109024
    Inhibition of mitochondrial translation suppresses glioblastoma stem cell growth.
    Denise Sighel, Michela Notarangelo, Shintaro Aibara, Angela Re, Gianluca Ricci, Marianna Guida, Alessia Soldano, Valentina Adami, Chiara Ambrosini, Francesca Broso, Emanuele Filiberto Rosatti, Sara Longhi, Mariachiara Buccarelli, Quintino G D'Alessandris, Stefano Giannetti, Simone Pacioni, Lucia Ricci-Vitiani, Joanna Rorbach, Roberto Pallini, Sandrine Roulland, Alexey Amunts, Ines Mancini, Angelika Modelska, Alessandro Quattrone.
      Glioblastoma stem cells (GSCs) resist current glioblastoma (GBM) therapies. GSCs rely highly on oxidative phosphorylation (OXPHOS), whose function requires mitochondrial translation. Here we explore the therapeutic potential of targeting mitochondrial translation and report the results of high-content screening with putative blockers of mitochondrial ribosomes. We identify the bacterial antibiotic quinupristin/dalfopristin (Q/D) as an effective suppressor of GSC growth. Q/D also decreases the clonogenicity of GSCs in vitro, consequently dysregulating the cell cycle and inducing apoptosis. Cryoelectron microscopy (cryo-EM) reveals that Q/D binds to the large mitoribosomal subunit, inhibiting mitochondrial protein synthesis and functionally dysregulating OXPHOS complexes. These data suggest that targeting mitochondrial translation could be explored to therapeutically suppress GSC growth in GBM and that Q/D could potentially be repurposed for cancer treatment.
    Keywords:  OXPHOS; cryo-EM; dalfopristin; drug repurposing; glioblastoma; glioblastoma stem cells; high-content screening; mitochondrial translation; mitoribosome; quinupristin
    DOI:  https://doi.org/10.1016/j.celrep.2021.109024
  10. Appl Sci (Basel). 2021 Mar;pii: 2071. [Epub ahead of print]11(5):
    Modeling the Effects of Calcium Overload on Mitochondrial Ultrastructural Remodeling.
    Jasiel O Strubbe-Rivera, Jiahui Chen, Benjamin A West, Kristin N Parent, Guo-Wei Wei, Jason N Bazil.
      Mitochondrial cristae are dynamic invaginations of the inner membrane and play a key role in its metabolic capacity to produce ATP. Structural alterations caused by either genetic abnormalities or detrimental environmental factors impede mitochondrial metabolic fluxes and lead to a decrease in their ability to meet metabolic energy requirements. While some of the key proteins associated with mitochondrial cristae are known, very little is known about how the inner membrane dynamics are involved in energy metabolism. In this study, we present a computational strategy to understand how cristae are formed using a phase-based separation approach of both the inner membrane space and matrix space, which are explicitly modeled using the Cahn-Hilliard equation. We show that cristae are formed as a consequence of minimizing an energy function associated with phase interactions which are subject to geometric boundary constraints. We then extended the model to explore how the presence of calcium phosphate granules, entities that form in calcium overload conditions, exert a devastating inner membrane remodeling response that reduces the capacity for mitochondria to produce ATP. This modeling approach can be extended to include arbitrary geometrical constraints, the spatial heterogeneity of enzymes, and electrostatic effects to mechanize the impact of ultrastructural changes on energy metabolism.
    Keywords:  bioenergetics; calcium overload; computer simulation; cristae; cryo-electron microscopy; mathematical modeling; membrane topology; mitochondria; mitochondria ultrastructure; mitochondrial dynamics
    DOI:  https://doi.org/10.3390/app11052071
  11. Int J Mol Sci. 2021 Apr 02. pii: 3730. [Epub ahead of print]22(7):
    Bcl-2 Family of Proteins in the Control of Mitochondrial Calcium Signalling: An Old Chap with New Roles.
    Jordan L Morris, Germain Gillet, Julien Prudent, Nikolay Popgeorgiev.
      Bcl-2 family proteins are considered as one of the major regulators of apoptosis. Indeed, this family is known to control the mitochondrial outer membrane permeabilization (MOMP): a central step in the mitochondrial pathway of apoptosis. However, in recent years Bcl-2 family members began to emerge as a new class of intracellular calcium (Ca2+) regulators. At mitochondria-ER contacts (MERCs) these proteins are able to interact with major Ca2+ transporters, thus controlling mitochondrial Ca2+ homeostasis and downstream Ca2+ signalling pathways. Beyond the regulation of cell survival, this Bcl-2-dependent control over the mitochondrial Ca2+ dynamics has far-reaching consequences on the physiology of the cell. Here, we review how the Bcl-2 family of proteins mechanistically regulate mitochondrial Ca2+ homeostasis and how this regulation orchestrates cell death/survival decisions as well as the non-apoptotic process of cell migration.
    Keywords:  Bcl-2 proteins; IP3R; VDAC; apoptosis; cell migration; mitochondrial calcium homeostasis
    DOI:  https://doi.org/10.3390/ijms22073730
  12. Int J Mol Sci. 2021 Apr 07. pii: 3827. [Epub ahead of print]22(8):
    Human Mitoribosome Biogenesis and Its Emerging Links to Disease.
    Maria Isabel G Lopez Sanchez, Annika Krüger, Dmitrii I Shiriaev, Yong Liu, Joanna Rorbach.
      Mammalian mitochondrial ribosomes (mitoribosomes) synthesize a small subset of proteins, which are essential components of the oxidative phosphorylation machinery. Therefore, their function is of fundamental importance to cellular metabolism. The assembly of mitoribosomes is a complex process that progresses through numerous maturation and protein-binding events coordinated by the actions of several assembly factors. Dysregulation of mitoribosome production is increasingly recognized as a contributor to metabolic and neurodegenerative diseases. In recent years, mutations in multiple components of the mitoribosome assembly machinery have been associated with a range of human pathologies, highlighting their importance to cell function and health. Here, we provide a review of our current understanding of mitoribosome biogenesis, highlighting the key factors involved in this process and the growing number of mutations in genes encoding mitoribosomal RNAs, proteins, and assembly factors that lead to human disease.
    Keywords:  assembly factors; mitochondria; mitochondrial disease; mitoribosome; rRNA
    DOI:  https://doi.org/10.3390/ijms22083827
  13. Antioxidants (Basel). 2021 Apr 28. pii: 696. [Epub ahead of print]10(5):
    Mitochondrial Transplantation Modulates Inflammation and Apoptosis, Alleviating Tendinopathy Both In Vivo and In Vitro.
    Ji Min Lee, Jung Wook Hwang, Mi Jin Kim, Sang Youn Jung, Kyung-Soo Kim, Eun Hee Ahn, Kyunghoon Min, Yong-Soo Choi.
      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.
    Keywords:  apoptosis; inflammation; mitochondrial dynamics; mitochondrial transplantation; tendinopathy; tenocyte
    DOI:  https://doi.org/10.3390/antiox10050696
  14. Int J Mol Sci. 2021 Apr 09. pii: 3903. [Epub ahead of print]22(8):
    Mitophagy in Human Diseases.
    Laura Doblado, Claudia Lueck, Claudia Rey, Alejandro K Samhan-Arias, Ignacio Prieto, Alessandra Stacchiotti, Maria Monsalve.
      Mitophagy is a selective autophagic process, essential for cellular homeostasis, that eliminates dysfunctional mitochondria. Activated by inner membrane depolarization, it plays an important role during development and is fundamental in highly differentiated post-mitotic cells that are highly dependent on aerobic metabolism, such as neurons, muscle cells, and hepatocytes. Both defective and excessive mitophagy have been proposed to contribute to age-related neurodegenerative diseases, such as Parkinson's and Alzheimer's diseases, metabolic diseases, vascular complications of diabetes, myocardial injury, muscle dystrophy, and liver disease, among others. Pharmacological or dietary interventions that restore mitophagy homeostasis and facilitate the elimination of irreversibly damaged mitochondria, thus, could serve as potential therapies in several chronic diseases. However, despite extraordinary advances in this field, mainly derived from in vitro and preclinical animal models, human applications based on the regulation of mitochondrial quality in patients have not yet been approved. In this review, we summarize the key selective mitochondrial autophagy pathways and their role in prevalent chronic human diseases and highlight the potential use of specific interventions.
    Keywords:  Alzheimer’s; Huntington’s; PINK1; Parkin; Parkinson’s; aging; atherosclerosis; dementia; diabetes; exercise; heart failure; mice; mitophagy; muscle wasting; rats
    DOI:  https://doi.org/10.3390/ijms22083903
  15. Int J Mol Sci. 2021 Apr 27. pii: 4607. [Epub ahead of print]22(9):
    A Crucial Role of Mitochondrial Dynamics in Dehydration Resistance in Saccharomyces cerevisiae.
    Chang-Lin Chen, Ying-Chieh Chen, Wei-Ling Huang, Steven Lin, Rimantas Daugelavičius, Alexander Rapoport, Chuang-Rung Chang.
      Mitochondria are dynamic organelles as they continuously undergo fission and fusion. These dynamic processes conduct not only mitochondrial network morphology but also activity regulation and quality control. Saccharomyces cerevisiae has a remarkable capacity to resist stress from dehydration/rehydration. Although mitochondria are noted for their role in desiccation tolerance, the mechanisms underlying these processes remains obscure. Here, we report that yeast cells that went through stationary growth phase have a better survival rate after dehydration/rehydration. Dynamic defective yeast cells with reduced mitochondrial genome cannot maintain the mitochondrial activity and survival rate of wild type cells. Our results demonstrate that yeast cells balance mitochondrial fusion and fission according to growth conditions, and the ability to adjust dynamic behavior aids the dehydration resistance by preserving mitochondria.
    Keywords:  dehydration; dynamics; mitochondria; yeast
    DOI:  https://doi.org/10.3390/ijms22094607
  16. Int J Mol Sci. 2021 Apr 27. pii: 4558. [Epub ahead of print]22(9):
    Role of PGC-1α in the Mitochondrial NAD+ Pool in Metabolic Diseases.
    Jin-Ho Koh, Jong-Yeon Kim.
      Mitochondria play vital roles, including ATP generation, regulation of cellular metabolism, and cell survival. Mitochondria contain the majority of cellular nicotinamide adenine dinucleotide (NAD+), which an essential cofactor that regulates metabolic function. A decrease in both mitochondria biogenesis and NAD+ is a characteristic of metabolic diseases, and peroxisome proliferator-activated receptor γ coactivator 1-α (PGC-1α) orchestrates mitochondrial biogenesis and is involved in mitochondrial NAD+ pool. Here we discuss how PGC-1α is involved in the NAD+ synthesis pathway and metabolism, as well as the strategy for increasing the NAD+ pool in the metabolic disease state.
    Keywords:  NAD+, SIRTs; PGC-1α; metabolic disease; mitochondria
    DOI:  https://doi.org/10.3390/ijms22094558
  17. Nat Metab. 2021 Apr 26.
    Cellular pyrimidine imbalance triggers mitochondrial DNA-dependent innate immunity.
    Hans-Georg Sprenger, Thomas MacVicar, Amir Bahat, Kai Uwe Fiedler, Steffen Hermans, Denise Ehrentraut, Katharina Ried, Dusanka Milenkovic, Nina Bonekamp, Nils-Göran Larsson, Hendrik Nolte, Patrick Giavalisco, Thomas Langer.
      Cytosolic mitochondrial DNA (mtDNA) elicits a type I interferon response, but signals triggering the release of mtDNA from mitochondria remain enigmatic. Here, we show that mtDNA-dependent immune signalling via the cyclic GMP-AMP synthase‒stimulator of interferon genes‒TANK-binding kinase 1 (cGAS-STING-TBK1) pathway is under metabolic control and is induced by cellular pyrimidine deficiency. The mitochondrial protease YME1L preserves pyrimidine pools by supporting de novo nucleotide synthesis and by proteolysis of the pyrimidine nucleotide carrier SLC25A33. Deficiency of YME1L causes inflammation in mouse retinas and in cultured cells. It drives the release of mtDNA and a cGAS-STING-TBK1-dependent inflammatory response, which requires SLC25A33 and is suppressed upon replenishment of cellular pyrimidine pools. Overexpression of SLC25A33 is sufficient to induce immune signalling by mtDNA. Similarly, depletion of cytosolic nucleotides upon inhibition of de novo pyrimidine synthesis triggers mtDNA-dependent immune responses in wild-type cells. Our results thus identify mtDNA release and innate immune signalling as a metabolic response to cellular pyrimidine deficiencies.
    DOI:  https://doi.org/10.1038/s42255-021-00385-9
  18. Int J Mol Sci. 2021 Apr 28. pii: 4670. [Epub ahead of print]22(9):
    The Novel Role of PGC1α in Bone Metabolism.
    Cinzia Buccoliero, Manuela Dicarlo, Patrizia Pignataro, Francesco Gaccione, Silvia Colucci, Graziana Colaianni, Maria Grano.
      Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α) is a protein that promotes transcription of numerous genes, particularly those responsible for the regulation of mitochondrial biogenesis. Evidence for a key role of PGC1α in bone metabolism is very recent. In vivo studies showed that PGC1α deletion negatively affects cortical thickness, trabecular organization and resistance to flexion, resulting in increased risk of fracture. Furthermore, in a mouse model of bone disease, PGC1α activation stimulates osteoblastic gene expression and inhibits atrogene transcription. PGC1α overexpression positively affects the activity of Sirtuin 3, a mitochondrial nicotinammide adenina dinucleotide (NAD)-dependent deacetylase, on osteoblastic differentiation. In vitro, PGC1α overexpression prevents the reduction of mitochondrial density, membrane potential and alkaline phosphatase activity caused by Sirtuin 3 knockdown in osteoblasts. Moreover, PGC1α influences the commitment of skeletal stem cells towards an osteogenic lineage, while negatively affects marrow adipose tissue accumulation. In this review, we will focus on recent findings about PGC1α action on bone metabolism, in vivo and in vitro, and in pathologies that cause bone loss, such as osteoporosis and type 2 diabetes.
    Keywords:  bone metabolism; metabolic regulations; mitochondria
    DOI:  https://doi.org/10.3390/ijms22094670
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