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Thomas C, Erni R, Wu JY, Fischer F, Lamers G, Grigolon G, Mitchell SJ, Zarse K, Carreira EM, Ristow M. A naturally occurring polyacetylene isolated from carrots promotes health and delays signatures of aging. Nat Commun 2023; 14:8142. [PMID: 38065964 PMCID: PMC10709416 DOI: 10.1038/s41467-023-43672-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 11/16/2023] [Indexed: 12/18/2023] Open
Abstract
To ameliorate or even prevent signatures of aging in ultimately humans, we here report the identification of a previously undescribed polyacetylene contained in the root of carrots (Daucus carota), hereafter named isofalcarintriol, which we reveal as potent promoter of longevity in the nematode C. elegans. We assign the absolute configuration of the compound as (3 S,8 R,9 R,E)-heptadeca-10-en-4,6-diyne-3,8,9-triol, and develop a modular asymmetric synthesis route for all E-isofalcarintriol stereoisomers. At the molecular level, isofalcarintriol affects cellular respiration in mammalian cells, C. elegans, and mice, and interacts with the α-subunit of the mitochondrial ATP synthase to promote mitochondrial biogenesis. Phenotypically, this also results in decreased mammalian cancer cell growth, as well as improved motility and stress resistance in C. elegans, paralleled by reduced protein accumulation in nematodal models of neurodegeneration. In addition, isofalcarintriol supplementation to both wild-type C57BL/6NRj mice on high-fat diet, and aged mice on chow diet results in improved glucose metabolism, increased exercise endurance, and attenuated parameters of frailty at an advanced age. Given these diverse effects on health parameters in both nematodes and mice, isofalcarintriol might become a promising mitohormesis-inducing compound to delay, ameliorate, or prevent aging-associated diseases in humans.
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Affiliation(s)
- Carolin Thomas
- Laboratory of Energy Metabolism, Institute of Translational Medicine, Department of Health Sciences and Technology, Swiss Federal Institute (ETH) Zurich, Schorenstrasse 16, 8603, Schwerzenbach, Switzerland
| | - Reto Erni
- Laboratory of Chemistry and Applied Biosciences, Department of Organic Chemistry, Swiss Federal Institute (ETH) Zurich, Vladimir-Prelog-Weg 1-5/10, Zurich, 8093, Switzerland
- Biozentrum, University of Basel, Basel, 4056, Switzerland
| | - Jia Yee Wu
- Laboratory of Energy Metabolism, Institute of Translational Medicine, Department of Health Sciences and Technology, Swiss Federal Institute (ETH) Zurich, Schorenstrasse 16, 8603, Schwerzenbach, Switzerland
| | - Fabian Fischer
- Laboratory of Energy Metabolism, Institute of Translational Medicine, Department of Health Sciences and Technology, Swiss Federal Institute (ETH) Zurich, Schorenstrasse 16, 8603, Schwerzenbach, Switzerland
- CureVac SE, Tübingen, 72076, Germany
| | - Greta Lamers
- Laboratory of Energy Metabolism, Institute of Translational Medicine, Department of Health Sciences and Technology, Swiss Federal Institute (ETH) Zurich, Schorenstrasse 16, 8603, Schwerzenbach, Switzerland
| | - Giovanna Grigolon
- Laboratory of Energy Metabolism, Institute of Translational Medicine, Department of Health Sciences and Technology, Swiss Federal Institute (ETH) Zurich, Schorenstrasse 16, 8603, Schwerzenbach, Switzerland
| | - Sarah J Mitchell
- Ludwig Princeton Branch, Princeton University, Princeton, NJ, 08540, USA
| | - Kim Zarse
- Laboratory of Energy Metabolism, Institute of Translational Medicine, Department of Health Sciences and Technology, Swiss Federal Institute (ETH) Zurich, Schorenstrasse 16, 8603, Schwerzenbach, Switzerland
- Institute of Experimental Endocrinology, Charité Universitätsmedizin Berlin, Berlin, 10117, Germany
| | - Erick M Carreira
- Laboratory of Chemistry and Applied Biosciences, Department of Organic Chemistry, Swiss Federal Institute (ETH) Zurich, Vladimir-Prelog-Weg 1-5/10, Zurich, 8093, Switzerland.
| | - Michael Ristow
- Laboratory of Energy Metabolism, Institute of Translational Medicine, Department of Health Sciences and Technology, Swiss Federal Institute (ETH) Zurich, Schorenstrasse 16, 8603, Schwerzenbach, Switzerland.
- Institute of Experimental Endocrinology, Charité Universitätsmedizin Berlin, Berlin, 10117, Germany.
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2
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Fung TS, Chakrabarti R, Higgs HN. The multiple links between actin and mitochondria. Nat Rev Mol Cell Biol 2023; 24:651-667. [PMID: 37277471 PMCID: PMC10528321 DOI: 10.1038/s41580-023-00613-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/26/2023] [Indexed: 06/07/2023]
Abstract
Actin plays many well-known roles in cells, and understanding any specific role is often confounded by the overlap of multiple actin-based structures in space and time. Here, we review our rapidly expanding understanding of actin in mitochondrial biology, where actin plays multiple distinct roles, exemplifying the versatility of actin and its functions in cell biology. One well-studied role of actin in mitochondrial biology is its role in mitochondrial fission, where actin polymerization from the endoplasmic reticulum through the formin INF2 has been shown to stimulate two distinct steps. However, roles for actin during other types of mitochondrial fission, dependent on the Arp2/3 complex, have also been described. In addition, actin performs functions independent of mitochondrial fission. During mitochondrial dysfunction, two distinct phases of Arp2/3 complex-mediated actin polymerization can be triggered. First, within 5 min of dysfunction, rapid actin assembly around mitochondria serves to suppress mitochondrial shape changes and to stimulate glycolysis. At a later time point, at more than 1 h post-dysfunction, a second round of actin polymerization prepares mitochondria for mitophagy. Finally, actin can both stimulate and inhibit mitochondrial motility depending on the context. These motility effects can either be through the polymerization of actin itself or through myosin-based processes, with myosin 19 being an important mitochondrially attached myosin. Overall, distinct actin structures assemble in response to diverse stimuli to affect specific changes to mitochondria.
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Affiliation(s)
- Tak Shun Fung
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH, USA
- Department of Cancer Biology and Genetics, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Rajarshi Chakrabarti
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH, USA
- MitoCare Center, Department of Pathology and Genomic Medicine, Thomas Jefferson University, Philadelphia, PA, USA
| | - Henry N Higgs
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH, USA.
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3
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Sánchez-Vázquez VH, Martínez-Martínez E, Gallegos-Gómez ML, Arias JM, Pallafacchina G, Rizzuto R, Guerrero-Hernández A. Heterogeneity of the endoplasmic reticulum Ca 2+ store determines colocalization with mitochondria. Cell Calcium 2023; 109:102688. [PMID: 36538845 DOI: 10.1016/j.ceca.2022.102688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 11/14/2022] [Accepted: 12/09/2022] [Indexed: 12/14/2022]
Abstract
Contact sites between the endoplasmic reticulum (ER) and mitochondria play a pivotal role in cell signaling, and the interaction between these organelles is dynamic and finely regulated. We have studied the role of ER Ca2+ concentration ([Ca2+]ER) in modulating this association in HeLa and HEK293 cells and human fibroblasts. According to Manders' coefficient, ER-mitochondria colocalization varied depending on the ER marker; it was the highest with ER-Tracker and the lowest with ER Ca2+ indicators (Mag-Fluo-4, erGAP3, and G-CEPIA1er) in both HeLa cells and human fibroblasts. Only GEM-CEPIA1er displayed a high colocalization with elongated mitochondria in HeLa cells, this ER Ca2+ indicator reveals low Ca2+ regions because this ion quenches its fluorescence. On the contrary, the typical rounded and fragmented mitochondria of HEK293 cells colocalized with Mag-Fluo-4 and, to a lesser extent, with GEM-CEPIA1er. The ablation of the three IP3R isoforms in HEK293 cells increased mitochondria-GEM-CEPIA1er colocalization. This pattern of colocalization was inversely correlated with the rate of ER Ca2+ leak evoked by thapsigargin (Tg). Moreover, Tg and Histamine in the absence of external Ca2+ increased mitochondria-ER colocalization. On the contrary, in the presence of external Ca2+, both Bafilomycin A1 and Tg reduced the mitochondria-ER interaction. Notably, knocking down MCU decreased mitochondria-ER colocalization. Overall, our data suggest that the [Ca2+] is not homogenous within the ER lumen and that mitochondria-ER interaction is modulated by the ER Ca2+ leak and the [Ca2+]i.
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Affiliation(s)
| | | | | | - Juan M Arias
- Programa de Neurociencias-UIICSE, Facultad de Estudios Superiores Iztacala, UNAM; Tlalnepantla de Baz, Estado de México, 54090, Mexico
| | - Giorgia Pallafacchina
- CNR, Neuroscience Institute, Padua, 35131. Italy; Department of Biomedical Sciences, University of Padua, Padua, 35131. Italy
| | - Rosario Rizzuto
- Department of Biomedical Sciences, University of Padua, Padua, 35131. Italy
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4
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Fung TS, Chakrabarti R, Kollasser J, Rottner K, Stradal TEB, Kage F, Higgs HN. Parallel kinase pathways stimulate actin polymerization at depolarized mitochondria. Curr Biol 2022; 32:1577-1592.e8. [PMID: 35290799 PMCID: PMC9078333 DOI: 10.1016/j.cub.2022.02.058] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 02/04/2022] [Accepted: 02/21/2022] [Indexed: 12/31/2022]
Abstract
Mitochondrial damage (MtD) represents a dramatic change in cellular homeostasis, necessitating metabolic changes and stimulating mitophagy. One rapid response to MtD is a rapid peri-mitochondrial actin polymerization termed ADA (acute damage-induced actin). The activation mechanism for ADA is unknown. Here, we use mitochondrial depolarization or the complex I inhibitor metformin to induce ADA. We show that two parallel signaling pathways are required for ADA. In one pathway, increased cytosolic calcium in turn activates PKC-β, Rac, WAVE regulatory complex, and Arp2/3 complex. In the other pathway, a drop in cellular ATP in turn activates AMPK (through LKB1), Cdc42, and FMNL formins. We also identify putative guanine nucleotide exchange factors for Rac and Cdc42, Trio and Fgd1, respectively, whose phosphorylation states increase upon mitochondrial depolarization and whose suppression inhibits ADA. The depolarization-induced calcium increase is dependent on the mitochondrial sodium-calcium exchanger NCLX, suggesting initial mitochondrial calcium efflux. We also show that ADA inhibition results in enhanced mitochondrial shape changes upon mitochondrial depolarization, suggesting that ADA inhibits these shape changes. These depolarization-induced shape changes are not fragmentation but a circularization of the inner mitochondrial membrane, which is dependent on the inner mitochondrial membrane protease Oma1. ADA inhibition increases the proteolytic processing of an Oma1 substrate, the dynamin GTPase Opa1. These results show that ADA requires the combined action of the Arp2/3 complex and formin proteins to polymerize a network of actin filaments around mitochondria and that the ADA network inhibits the rapid mitochondrial shape changes that occur upon mitochondrial depolarization.
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Affiliation(s)
- Tak Shun Fung
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH 03755, USA
| | - Rajarshi Chakrabarti
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH 03755, USA
| | - Jana Kollasser
- Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Klemens Rottner
- Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany; Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany
| | - Theresia E B Stradal
- Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Frieda Kage
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH 03755, USA
| | - Henry N Higgs
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH 03755, USA.
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5
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Pohan G, Espinosa JA, Chen S, Ang KK, Arkin MR, Markossian S. Multiparametric High-Content Assays to Measure Cell Health and Oxidative Damage as a Model for Drug-Induced Liver Injury. ACTA ACUST UNITED AC 2021; 12:e90. [PMID: 33315311 DOI: 10.1002/cpch.90] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Drug-induced liver injury is an important cause of non-approval in drug development and the withdrawal of already approved drugs from the market. Screening human hepatic cell lines for toxicity has been used extensively to predict drug-induced liver injury in preclinical drug development. Assessing hepatic-cell health with more diverse markers will increase the value of in vitro assays and help predict the mechanism of toxicity. We describe three live cell-based assays using HepG2 cells to measure cell health parameters indicative of hepatotoxicity. The first assay measures cellular ATP levels using luciferase. The second and third assays are multiparametric high-content screens covering a panel of cell health markers including cell count, mitochondrial membrane potential and structure, nuclear morphology, vacuolar density, and reactive oxygen species and glutathione levels. © 2020 Wiley Periodicals LLC. Basic Protocol 1: Measurement of cellular ATP content Basic Protocol 2: High-content analysis assay to assess cell count, mitochondrial membrane potential and structure, and reactive oxygen species Basic Protocol 3: High-content analysis assay to assess nuclear morphology, vacuoles, and glutathione content Support Protocol 1: Subculturing and maintaining HepG2 cells Support Protocol 2: Plating HepG2 cell line Support Protocol 3: Transferring compounds by pin tool Support Protocol 4: Generating dose-response curves.
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Affiliation(s)
- Grace Pohan
- Small Molecule Discovery Center and Department of Pharmaceutical Chemistry, University of California, San Francisco, California
| | - Jether Amos Espinosa
- Small Molecule Discovery Center and Department of Pharmaceutical Chemistry, University of California, San Francisco, California
| | | | - Kenny K Ang
- Small Molecule Discovery Center and Department of Pharmaceutical Chemistry, University of California, San Francisco, California
| | - Michelle R Arkin
- Small Molecule Discovery Center and Department of Pharmaceutical Chemistry, University of California, San Francisco, California
| | - Sarine Markossian
- Small Molecule Discovery Center and Department of Pharmaceutical Chemistry, University of California, San Francisco, California.,Current address: National Center for Advancing Translational Sciences, Rockville, Maryland
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6
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Abstract
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.
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Affiliation(s)
- Antonina J Kruppa
- Cambridge Institute for Medical Research, Department of Clinical Biochemistry, University of Cambridge, Cambridge Biomedical Campus, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
| | - Folma Buss
- Cambridge Institute for Medical Research, Department of Clinical Biochemistry, University of Cambridge, Cambridge Biomedical Campus, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
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7
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Espinosa JA, Pohan G, Arkin MR, Markossian S. Real-Time Assessment of Mitochondrial Toxicity in HepG2 Cells Using the Seahorse Extracellular Flux Analyzer. Curr Protoc 2021; 1:e75. [PMID: 33735523 DOI: 10.1002/cpz1.75] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The liver is the primary organ responsible for drug detoxification. Drug-induced liver injury (DILI) is a leading cause of attrition during drug development and is one of the main reasons that drugs are withdrawn from the market. Hence, the prevention of DILI plays a central role in the overall drug-discovery process. Most of the liver's energy supply comes in the form of adenosine triphosphate (ATP), which is largely generated by mitochondria. This article describes the evaluation of drug-induced mitochondrial dysfunction using the Seahorse Extracellular Flux Analyzer (Agilent). The described protocols detail the accurate measurement of ATP production rate in HepG2 cells after exposure to a panel of potentially toxic compounds. This assay measures changes in extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) as indicators of glycolysis and mitochondrial respiration-the two major energy-generating pathways in a cell. This assay provides a useful model to predict mitochondrial dysfunction-mediated DILI. © 2021 Wiley Periodicals LLC. Basic Protocol: Measurement of cellular ECAR, OCR, and ATP production in live HepG2 cells Support Protocol 1: Culturing and maintaining of HepG2 cells Support Protocol 2: Determining optimal cell density per well.
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Affiliation(s)
- Jether Amos Espinosa
- Small Molecule Discovery Center and Department of Pharmaceutical Chemistry, University of California, San Francisco, California
| | - Grace Pohan
- Small Molecule Discovery Center and Department of Pharmaceutical Chemistry, University of California, San Francisco, California
| | - Michelle R Arkin
- Small Molecule Discovery Center and Department of Pharmaceutical Chemistry, University of California, San Francisco, California
| | - Sarine Markossian
- Small Molecule Discovery Center and Department of Pharmaceutical Chemistry, University of California, San Francisco, California.,Current Address: National Center for Advancing Translational Sciences, Rockville, Maryland
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8
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Aplak E, von Montfort C, Haasler L, Stucki D, Steckel B, Reichert AS, Stahl W, Brenneisen P. CNP mediated selective toxicity on melanoma cells is accompanied by mitochondrial dysfunction. PLoS One 2020; 15:e0227926. [PMID: 31951630 PMCID: PMC6968876 DOI: 10.1371/journal.pone.0227926] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 01/02/2020] [Indexed: 12/16/2022] Open
Abstract
Cerium (Ce) oxide nanoparticles (CNP; nanoceria) are reported to have cytotoxic effects on certain cancerous cell lines, while at the same concentration they show no cytotoxicity on normal (healthy) cells. Redox-active CNP exhibit both selective prooxidative as well as antioxidative properties. The former is proposed to be responsible for impairment of tumor growth and invasion and the latter for rescuing normal cells from reactive oxygen species (ROS)-induced damage. Here we address possible underlying mechanisms of prooxidative effects of CNP in a metastatic human melanoma cell line. Malignant melanoma is the most aggressive form of skin cancer, and once it becomes metastatic the prognosis is very poor. We have shown earlier that CNP selectively kill A375 melanoma cells by increasing intracellular ROS levels, whose basic amount is significantly higher than in the normal (healthy) counterpart, the melanocytes. Here we show that CNP initiate a mitochondrial increase of ROS levels accompanied by an increase in mitochondrial thiol oxidation. Furthermore, we observed CNP-induced changes in mitochondrial bioenergetics, dynamics, and cristae morphology demonstrating mitochondrial dysfunction which finally led to tumor cell death. CNP-induced cell death is abolished by administration of PEG-conjugated catalase. Overall, we propose that cerium oxide nanoparticles mediate cell death via hydrogen peroxide production linked to mitochondrial dysfunction.
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Affiliation(s)
- Elif Aplak
- Institute of Biochemistry and Molecular Biology I, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Claudia von Montfort
- Institute of Biochemistry and Molecular Biology I, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- * E-mail:
| | - Lisa Haasler
- Institute of Biochemistry and Molecular Biology I, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - David Stucki
- Institute of Biochemistry and Molecular Biology I, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Bodo Steckel
- Department of Molecular Cardiology, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Andreas S. Reichert
- Institute of Biochemistry and Molecular Biology I, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Wilhelm Stahl
- Institute of Biochemistry and Molecular Biology I, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Peter Brenneisen
- Institute of Biochemistry and Molecular Biology I, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
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9
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Kang SWS, Cogger VC, Le Couteur DG, Fu D. Multiple cellular pathways regulate lipid droplet homeostasis for the establishment of polarity in collagen sandwich-cultured hepatocytes. Am J Physiol Cell Physiol 2019; 317:C942-C952. [DOI: 10.1152/ajpcell.00051.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hepatocyte polarization is energy dependent. The establishment of polarization in collagen sandwich culture of hepatocytes requires utilization of lipid droplets and mitochondrial β-oxidation to supply ATP. Multiple cellular pathways are involved in lipid droplet homeostasis; however, mechanistic insights of how hepatocytes utilize lipid droplets during polarization remain elusive. The current study investigated the effects of various pathways involved in lipid droplet homeostasis on bioenergetics during hepatocyte polarization. The results showed that hepatocytes were dependent on lipolysis of lipid droplets to release fatty acids for β-oxidation. Inhibition of lipolysis significantly decreased cellular fatty acid and ATP levels and inhibited hepatocyte polarization, revealing that lipolysis was an important mechanism for providing energy for hepatocyte polarization. The results also demonstrated that autophagic degradation of lipid droplets (lipophagy) was not essential for breaking down lipid droplets. Conversely, autophagy contributed to lipid droplet formation and played a key role in sustaining lipid droplet stores for energy production. In addition, cholesterol biosynthesis/cholesterol esterification and de novo fatty acid synthesis also contributed to maintaining lipid droplet stores for bioenergetics during hepatocyte polarization. In summary, multiple cellular pathways are coordinated to maintain lipid droplet homeostasis and sustain fatty acid β-oxidation during hepatocyte polarization.
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Affiliation(s)
- Sun Woo Sophie Kang
- Ageing and Alzheimers Institute, ANZAC Research Institute, Concord Clinical School/Sydney Medical School, Concord, New South Wales, Australia
- Faculty of Pharmacy, The University of Sydney, Sydney, New South Wales, Australia
- Charles Perkins Centre, The University of Sydney, Sydney, New South Wales, Australia
| | - Victoria C. Cogger
- Ageing and Alzheimers Institute, ANZAC Research Institute, Concord Clinical School/Sydney Medical School, Concord, New South Wales, Australia
- Charles Perkins Centre, The University of Sydney, Sydney, New South Wales, Australia
| | - David G. Le Couteur
- Ageing and Alzheimers Institute, ANZAC Research Institute, Concord Clinical School/Sydney Medical School, Concord, New South Wales, Australia
- Charles Perkins Centre, The University of Sydney, Sydney, New South Wales, Australia
| | - Dong Fu
- Faculty of Pharmacy, The University of Sydney, Sydney, New South Wales, Australia
- UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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10
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Fung TS, Ji WK, Higgs HN, Chakrabarti R. Two distinct actin filament populations have effects on mitochondria, with differences in stimuli and assembly factors. J Cell Sci 2019; 132:jcs234435. [PMID: 31413070 PMCID: PMC6765187 DOI: 10.1242/jcs.234435] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 08/07/2019] [Indexed: 12/12/2022] Open
Abstract
Recent studies show that mitochondria and actin filaments work together in two contexts: (1) increased cytoplasmic calcium induces cytoplasmic actin polymerization that stimulates mitochondrial fission and (2) mitochondrial depolarization causes actin assembly around mitochondria, with roles in mitophagy. It is unclear whether these two processes utilize similar actin assembly mechanisms. Here, we show that these are distinct actin assembly mechanisms in the acute phase after treatment (<10 min). Calcium-induced actin assembly is INF2 dependent and Arp2/3 complex independent, whereas depolarization-induced actin assembly is Arp2/3 complex dependent and INF2 independent. The two types of actin polymerization are morphologically distinct, with calcium-induced filaments throughout the cytosol and depolarization-induced filaments as 'clouds' around depolarized mitochondria. We have previously shown that calcium-induced actin stimulates increases in both mitochondrial calcium and recruitment of the dynamin GTPase Drp1 (also known as DNM1L). In contrast, depolarization-induced actin is temporally associated with extensive mitochondrial dynamics that do not result in mitochondrial fission, but in circularization of the inner mitochondrial membrane (IMM). These dynamics are dependent on the protease OMA1 and independent of Drp1. Actin cloud inhibition causes increased IMM circularization, suggesting that actin clouds limit these dynamics.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Tak Shun Fung
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Wei-Ke Ji
- Department of Biochemistry and Molecular Biology, School of Basic Medicine and the Collaborative Innovation Center for Brain Science, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Henry N Higgs
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Rajarshi Chakrabarti
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
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11
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Takase S, Kurokawa R, Kondoh Y, Honda K, Suzuki T, Kawahara T, Ikeda H, Dohmae N, Osada H, Shin-ya K, Kushiro T, Yoshida M, Matsumoto K. Mechanism of Action of Prethioviridamide, an Anticancer Ribosomally Synthesized and Post-Translationally Modified Peptide with a Polythioamide Structure. ACS Chem Biol 2019; 14:1819-1828. [PMID: 31365229 DOI: 10.1021/acschembio.9b00410] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Thioviridamide, prethioviridamide, and JBIR-140, which are ribosomally synthesized and post-translationally modified peptides (RiPPs) possessing five thioamide bonds, induce selective apoptosis in various cancer cells, especially those expressing the adenovirus oncogene E1A. However, the target protein of this unique family of bioactive compounds was previously unknown. To investigate the mechanism of action, we adopted a combined approach of genome-wide shRNA library screening, transcriptome profiling, and biochemical identification of prethioviridamide-binding proteins. An shRNA screen identified 63 genes involved in cell sensitivity to prethioviridamide, which included translation initiation factors, aminoacyl tRNA synthetases, and mitochondrial proteins. Transcriptome profiling and subsequent analysis revealed that prethioviridamide induces the integrated stress response (ISR) through the GCN2-ATF4 pathway, which is likely to cause cell death. Furthermore, we found that prethioviridamide binds and inhibits respiratory chain complex V (F1Fo-ATP synthase) in mitochondria, suggesting that inhibition of complex V leads to activation of the GCN2-ATF4 pathway. These results imply that the members of a unique family of RiPPs with polythioamide structure target mitochondria to induce the ISR.
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Affiliation(s)
- Shohei Takase
- Chemical Genomics Research Group, RIKEN Center for Sustainable Resource Science, Saitama 351-0198, Japan
- School of Agriculture, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan
| | - Rumi Kurokawa
- Chemical Genomics Research Group, RIKEN Center for Sustainable Resource Science, Saitama 351-0198, Japan
| | - Yasumitsu Kondoh
- Chemical Biology Research Group, RIKEN Center for Sustainable Resource Science, Saitama 351-0198, Japan
| | - Kaori Honda
- Chemical Biology Research Group, RIKEN Center for Sustainable Resource Science, Saitama 351-0198, Japan
| | - Takehiro Suzuki
- Biomolecular Characterization Unit, RIKEN Center for Sustainable Resource Science, Saitama 351-0198, Japan
| | - Teppei Kawahara
- Japan Biological Informatics Consortium (JBIC), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan
| | - Haruo Ikeda
- Kitasato Institute for Life Sciences, Kitasato University, 1-15-1 Kitasato, Sagamihara, Kanagawa 252-0373, Japan
| | - Naoshi Dohmae
- Biomolecular Characterization Unit, RIKEN Center for Sustainable Resource Science, Saitama 351-0198, Japan
| | - Hiroyuki Osada
- Chemical Biology Research Group, RIKEN Center for Sustainable Resource Science, Saitama 351-0198, Japan
| | - Kazuo Shin-ya
- National Institute of Advanced Industrial Science and Technology (AIST), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Tetsuo Kushiro
- School of Agriculture, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan
| | - Minoru Yoshida
- Chemical Genomics Research Group, RIKEN Center for Sustainable Resource Science, Saitama 351-0198, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
- Seed Compounds Exploratory Unit for Drug Discovery Platform, Drug Discovery Platforms Cooperation Division, RIKEN Center for Sustainable Resource Science, Saitama 351-0198, Japan
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Tokyo 113-8657, Japan
| | - Ken Matsumoto
- Chemical Genomics Research Group, RIKEN Center for Sustainable Resource Science, Saitama 351-0198, Japan
- Seed Compounds Exploratory Unit for Drug Discovery Platform, Drug Discovery Platforms Cooperation Division, RIKEN Center for Sustainable Resource Science, Saitama 351-0198, Japan
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12
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Fu D, Cardona P, Ho H, Watkins PB, Brouwer KLR. Novel Mechanisms of Valproate Hepatotoxicity: Impaired Mrp2 Trafficking and Hepatocyte Depolarization. Toxicol Sci 2019; 171:431-442. [PMID: 31368504 PMCID: PMC6760262 DOI: 10.1093/toxsci/kfz154] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 07/02/2019] [Accepted: 07/03/2019] [Indexed: 12/14/2022] Open
Abstract
Drug-induced liver injury (DILI) remains a major challenge in drug development. Although numerous mechanisms for DILI have been identified, few studies have focused on loss of hepatocyte polarization as a DILI mechanism. The current study investigated the effects of valproate, an antiepileptic drug with DILI risk, on the cellular mechanisms responsible for loss of hepatocyte polarization. Fully polarized collagen sandwich-cultured rat hepatocytes were treated with valproate (1-20mM) for specified times (3-24hr). Hepatocyte viability was significantly decreased by 10mM and 20mM valproate. Valproate depolarized hepatocytes, even at non-cytotoxic concentrations (=5mM). Depolarization was associated with significantly decreased canalicular levels of multidrug resistance-associated protein 2 (Mrp2) resulting in reduced canalicular excretion of the Mrp2 substrate carboxydichlorofluorescein. The decreased canalicular Mrp2 was associated with intracellular accumulation of Mrp2 in Rab11-positive recycling endosomes and early endosomes. Mechanistic studies suggested that valproate inhibited canalicular trafficking of Mrp2. This effect of valproate on Mrp2 appeared to be selective in that valproate had less impact on canalicular levels of the bile salt export pump (Bsep) and no detectable effect on P-glycoprotein (P-gp) canalicular levels. Treatment with valproate for 24hr also significantly downregulated levels of tight junction-associated protein, zonula occludens 2 (ZO2), but appeared to have no effect on the levels of tight junction proteins claudin 1, claudin 2, occludin, ZO1 and ZO3. These findings reveal that two novel mechanisms may contribute to valproate hepatotoxicity: impaired canalicular trafficking of Mrp2 and disruption of ZO2-associated hepatocyte polarization.
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Affiliation(s)
- Dong Fu
- UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Panli Cardona
- UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Henry Ho
- UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Paul B Watkins
- UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Kim L R Brouwer
- UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC
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