1
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Alghamdi A. A detailed review of pharmacology of MFN1 (mitofusion-1)-mediated mitochondrial dynamics: Implications for cellular health and diseases. Saudi Pharm J 2024; 32:102012. [PMID: 38463181 PMCID: PMC10924208 DOI: 10.1016/j.jsps.2024.102012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 02/22/2024] [Indexed: 03/12/2024] Open
Abstract
The mitochondria are responsible for the production of cellular ATP, the regulation of cytosolic calcium levels, and the organization of numerous apoptotic proteins through the release of cofactors necessary for the activation of caspases. This level of functional adaptability can only be attained by sophisticated structural alignment. The morphology of the mitochondria does not remain unchanged throughout time; rather, it undergoes change as a result of processes known as fusion and fission. Fzo in flies, Fzo1 in yeast, and mitofusins in mammals are responsible for managing the outer mitochondrial membrane fusion process, whereas Mgm1 in yeast and optic atrophy 1 in mammals are responsible for managing the inner mitochondrial membrane fusion process. The fusion process is composed of two phases. MFN1, a GTPase that is located on the outer membrane of the mitochondria, is involved in the process of linking nearby mitochondria, maintaining the potential of the mitochondrial membrane, and apoptosis. This article offers specific information regarding the functions of MFN1 in a variety of cells and organs found in living creatures. According to the findings of the literature review, MFN1 plays an important part in a number of diseases and organ systems; nevertheless, the protein's function in other disease models and cell types has to be investigated in the near future so that it can be chosen as a promising marker for the therapeutic and diagnostic potentials it possesses. Overall, the major findings of this review highlight the pivotal role of mitofusin (MFN1) in regulating mitochondrial dynamics and its implications across various diseases, including neurodegenerative disorders, cardiovascular diseases, and metabolic syndromes. Our review identifies novel therapeutic targets within the MFN1 signaling pathways and underscores the potential of MFN1 modulation as a promising strategy for treating mitochondrial-related diseases. Additionally, the review calls for further research into MFN1's molecular mechanisms to unlock new avenues for clinical interventions, emphasizing the need for targeted therapies that address MFN1 dysfunction.
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Affiliation(s)
- Adel Alghamdi
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Al-Baha University, P.O. Box 1988 Al-Baha, Saudi Arabia
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2
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Wang H, Luo W, Chen H, Cai Z, Xu G. Mitochondrial dynamics and mitochondrial autophagy: Molecular structure, orchestrating mechanism and related disorders. Mitochondrion 2024; 75:101847. [PMID: 38246334 DOI: 10.1016/j.mito.2024.101847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 01/16/2024] [Accepted: 01/17/2024] [Indexed: 01/23/2024]
Abstract
Mitochondrial dynamics and autophagy play essential roles in normal cellular physiological activities, while abnormal mitochondrial dynamics and mitochondrial autophagy can cause cancer and related disorders. Abnormal mitochondrial dynamics usually occur in parallel with mitochondrial autophagy. Both have been reported to have a synergistic effect and can therefore complement or inhibit each other. Progress has been made in understanding the classical mitochondrial PINK1/Parkin pathway and mitochondrial dynamical abnormalities. Still, the mechanisms and regulatory pathways underlying the interaction between mitophagy and mitochondrial dynamics remain unexplored. Like other existing reviews, we review the molecular structure of proteins involved in mitochondrial dynamics and mitochondrial autophagy, and how their abnormalities can lead to the development of related diseases. We will also review the individual or synergistic effects of abnormal mitochondrial dynamics and mitophagy leading to cellular proliferation, differentiation and invasion. In addition, we explore the mechanisms underlying mitochondrial dynamics and mitochondrial autophagy to contribute to targeted and precise regulation of mitochondrial function. Through the study of abnormal mitochondrial dynamics and mitochondrial autophagy regulation mechanisms, as well as the role of early disease development, effective targets for mitochondrial function regulation can be proposed to enable accurate diagnosis and treatment of the associated disorders.
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Affiliation(s)
- Haoran Wang
- Department of Urology, Key Laboratory of Biological Targeting Diagnosis, Therapy and Rehabilitation of Guangdong Higher Education Institutes, The Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou 510700, China; Guangzhou Medical University, Guangzhou 511495, China
| | - Wenjun Luo
- Department of Urology, Key Laboratory of Biological Targeting Diagnosis, Therapy and Rehabilitation of Guangdong Higher Education Institutes, The Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou 510700, China
| | - Haoyu Chen
- Department of Urology, Key Laboratory of Biological Targeting Diagnosis, Therapy and Rehabilitation of Guangdong Higher Education Institutes, The Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou 510700, China
| | - Zhiduan Cai
- Department of Urology, Key Laboratory of Biological Targeting Diagnosis, Therapy and Rehabilitation of Guangdong Higher Education Institutes, The Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou 510700, China.
| | - Guibin Xu
- Department of Urology, Key Laboratory of Biological Targeting Diagnosis, Therapy and Rehabilitation of Guangdong Higher Education Institutes, The Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou 510700, China; Guangdong Provincial Key Laboratory of Urology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou 510230, China.
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3
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Han R, Chu M, Gao J, Wang J, Wang M, Ma Y, Jia T, Zhang X. Compound heterozygous variants of THG1L result in autosomal recessive cerebellar ataxia. J Hum Genet 2023; 68:843-848. [PMID: 37670026 DOI: 10.1038/s10038-023-01192-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 07/04/2023] [Accepted: 08/23/2023] [Indexed: 09/07/2023]
Abstract
tRNA-histidine guanyltransferase 1-like protein (THG1L), located in the mitochondria, plays a crucial role in the tRNA maturation process. Dysfunction of THG1L results in abnormal mitochondrial tRNA modification and neurodevelopmental disorders. To date, few studies have focused on THG1L-related cerebellar ataxia. Whole-exome sequencing revealed compound heterozygous variants NM_017872.5: [c.224A > G]; [c.369-8T > G] in THG1L in a 6-year-old boy with moderate cerebellar ataxia. The variant c.224A > G was demonstrated to downregulate its RNA and protein expression, and c.369-8 T > G resulted in a 7 bp insertion before exon 3. Our case expanded the gene variation and clinical spectrum of THG1L-related cerebellar ataxia.
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Affiliation(s)
- Rui Han
- Department of Pediatrics, The Third Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, Henan, China
| | - Manman Chu
- Department of Pediatrics, The Third Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, Henan, China
| | - Jinshuang Gao
- Clinical Laboratory, The Third Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, Henan, China
| | - Junling Wang
- Department of Pediatrics, The Third Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, Henan, China
| | - Mengyue Wang
- Department of Pediatrics, The Third Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, Henan, China
| | - Yichao Ma
- Department of Pediatrics, The Third Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, Henan, China
| | - Tianming Jia
- Department of Pediatrics, The Third Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, Henan, China
| | - Xiaoli Zhang
- Department of Pediatrics, The Third Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, Henan, China.
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4
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Vlieghe A, Niort K, Fumat H, Guigner JM, Cohen MM, Tareste D. Role of Lipids and Divalent Cations in Membrane Fusion Mediated by the Heptad Repeat Domain 1 of Mitofusin. Biomolecules 2023; 13:1341. [PMID: 37759741 PMCID: PMC10527301 DOI: 10.3390/biom13091341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 08/21/2023] [Accepted: 08/30/2023] [Indexed: 09/29/2023] Open
Abstract
Mitochondria are highly dynamic organelles that constantly undergo fusion and fission events to maintain their shape, distribution and cellular function. Mitofusin 1 and 2 proteins are two dynamin-like GTPases involved in the fusion of outer mitochondrial membranes (OMM). Mitofusins are anchored to the OMM through their transmembrane domain and possess two heptad repeat domains (HR1 and HR2) in addition to their N-terminal GTPase domain. The HR1 domain was found to induce fusion via its amphipathic helix, which interacts with the lipid bilayer structure. The lipid composition of mitochondrial membranes can also impact fusion. However, the precise mode of action of lipids in mitochondrial fusion is not fully understood. In this study, we examined the role of the mitochondrial lipids phosphatidylethanolamine (PE), cardiolipin (CL) and phosphatidic acid (PA) in membrane fusion induced by the HR1 domain, both in the presence and absence of divalent cations (Ca2+ or Mg2+). Our results showed that PE, as well as PA in the presence of Ca2+, effectively stimulated HR1-mediated fusion, while CL had a slight inhibitory effect. By considering the biophysical properties of these lipids in the absence or presence of divalent cations, we inferred that the interplay between divalent cations and specific cone-shaped lipids creates regions with packing defects in the membrane, which provides a favorable environment for the amphipathic helix of HR1 to bind to the membrane and initiate fusion.
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Affiliation(s)
- Anaïs Vlieghe
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), Inserm UMR-S 1266, Team Membrane Traffic in Healthy & Diseased Brain, 75014 Paris, France
| | - Kristina Niort
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), Inserm UMR-S 1266, Team Membrane Traffic in Healthy & Diseased Brain, 75014 Paris, France
| | - Hugo Fumat
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), Inserm UMR-S 1266, Team Membrane Traffic in Healthy & Diseased Brain, 75014 Paris, France
| | - Jean-Michel Guigner
- Sorbonne Université, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), CNRS UMR 7590, MNHN, IRD UR 206, 75005 Paris, France
| | - Mickaël M. Cohen
- Sorbonne Université, Institut de Biologie Physico-Chimique (IBPC), CNRS UMR 8226, Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, 75005 Paris, France
| | - David Tareste
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), Inserm UMR-S 1266, Team Membrane Traffic in Healthy & Diseased Brain, 75014 Paris, France
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5
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Kowaleski SJ, Hurmis CS, Coleman CN, Philips KD, Najor NA. SHE9 deletion mutants display fitness defects during diauxic shift in Saccharomyces cerevisiae . MICROPUBLICATION BIOLOGY 2023; 2023:10.17912/micropub.biology.000899. [PMID: 37577108 PMCID: PMC10422129 DOI: 10.17912/micropub.biology.000899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Figures] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 07/17/2023] [Accepted: 07/20/2023] [Indexed: 08/15/2023]
Abstract
Saccharomyces cerevisiae protein She9 is localized to the inner mitochondrial membrane and is required for normal mitochondrial morphology. While deletion mutants of SHE9 ( she9Δ ) are viable and display large ring-like mitochondrial structures, the molecular function of SHE9 is still unknown. We report a decreased growth of she9Δ cells during a diauxic shift, where mitochondria are primarily employing oxidative phosphorylation to generate ATP versus the alternative mechanism of glycolysis in high glucose conditions. Further bioinformatics analysis reveal putative functional protein associations, and proposes a model to aid in the understanding of the molecular function of She9.
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6
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Dhananjay S, Chandhok G, Neumann B. Novel putative interactors of FZO-1/mitofusin 2 identified using large-scale yeast two-hybrid screening in C. elegans. MICROPUBLICATION BIOLOGY 2022; 2022:10.17912/micropub.biology.000674. [PMID: 36530473 PMCID: PMC9756088 DOI: 10.17912/micropub.biology.000674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 11/23/2022] [Accepted: 11/28/2022] [Indexed: 01/14/2023]
Abstract
Mitochondria are energy-converting organelles that shift between fusion and fission states in order to perform a variety of essential functions. Disruption of these dynamics is detrimental to cellular health and is associated with a range of human diseases. Mitofusin 2 is an essential large GTPase protein that orchestrates fusion of outer mitochondria membranes, and mutations in the encoding gene are causative for Charcot-Marie-Tooth disease. In order to gain further insights into the function of this crucial protein, we have performed large-scale yeast two-hybrid screening to identify interactors of the orthologous protein in Caenorhabditis elegans (FZO-1) . From this screening, we identified 12 novel interactors of FZO-1/mitofusin 2 that, based on their known functions, are strong candidates for further study.
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Affiliation(s)
- Samiksha Dhananjay
- Neuroscience Program, Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne VIC 3800 Australia
| | - Gursimran Chandhok
- Neuroscience Program, Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne VIC 3800 Australia.
,
Correspondence to: Gursimran Chandhok (
)
| | - Brent Neumann
- Neuroscience Program, Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne VIC 3800 Australia.
,
Correspondence to: Brent Neumann (
)
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7
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Ozeir M, Cohen MM. From dynamin related proteins structures and oligomers to membrane fusion mediated by mitofusins. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148913. [PMID: 36057374 DOI: 10.1016/j.bbabio.2022.148913] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Revised: 07/17/2022] [Accepted: 08/26/2022] [Indexed: 06/15/2023]
Abstract
Mitochondria assemble in a highly dynamic network where interconnected tubules evolve in length and size through regulated cycles of fission and fusion of mitochondrial membranes thereby adapting to cellular needs. Mitochondrial fusion and fission processes are mediated by specific sets of mechano-chemical large GTPases that belong to the Dynamin-Related Proteins (DRPs) super family. DRPs bind to cognate membranes and auto-oligomerize to drive lipid bilayers remodeling in a nucleotide dependent manner. Although structural characterization and mechanisms of DRPs that mediate membrane fission are well established, the capacity of DRPs to mediate membrane fusion is only emerging. In this review, we discuss the distinct structures and mechanisms of DRPs that trigger the anchoring and fusion of biological membranes with a specific focus on mitofusins that are dedicated to the fusion of mitochondrial outer membranes. In particular, we will highlight oligomeric assemblies of distinct DRPs and confront their mode of action against existing models of mitofusins assemblies with emphasis on recent biochemical, structural and computational reports. As we will see, the literature brings valuable insights into the presumed macro-assemblies mitofusins may form during anchoring and fusion of mitochondrial outer membranes.
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Affiliation(s)
- Mohammad Ozeir
- Sorbonne Université, CNRS, UMR8226, Institut de Biologie Physico-Chimique, Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, F-75005 Paris, France
| | - Mickael M Cohen
- Sorbonne Université, CNRS, UMR8226, Institut de Biologie Physico-Chimique, Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, F-75005 Paris, France.
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8
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Mitochondria homeostasis: Biology and involvement in hepatic steatosis to NASH. Acta Pharmacol Sin 2022; 43:1141-1155. [PMID: 35105958 PMCID: PMC9061859 DOI: 10.1038/s41401-022-00864-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 01/09/2022] [Indexed: 12/13/2022] Open
Abstract
Mitochondrial biology and behavior are central to the physiology of liver. Multiple mitochondrial quality control mechanisms remodel mitochondrial homeostasis under physiological and pathological conditions. Mitochondrial dysfunction and damage induced by overnutrition lead to oxidative stress, inflammation, liver cell death, and collagen production, which advance hepatic steatosis to nonalcoholic steatohepatitis (NASH). Accumulating evidence suggests that specific interventions that target mitochondrial homeostasis, including energy metabolism, antioxidant effects, and mitochondrial quality control, have emerged as promising strategies for NASH treatment. However, clinical translation of these findings is challenging due to the complex and unclear mechanisms of mitochondrial homeostasis in the pathophysiology of NASH.
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9
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Suslov AV, Afanasyev MA, Degtyarev PA, Chumachenko PV, Ekta MB, Sukhorukov VN, Khotina VA, Yet SF, Sobenin IA, Postnov AY. Molecular Pathogenesis and the Possible Role of Mitochondrial Heteroplasmy in Thoracic Aortic Aneurysm. Life (Basel) 2021; 11:1395. [PMID: 34947926 PMCID: PMC8709403 DOI: 10.3390/life11121395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 11/26/2021] [Accepted: 12/07/2021] [Indexed: 12/06/2022] Open
Abstract
Thoracic aortic aneurysm (TAA) is a life-threatening condition associated with high mortality, in which the aortic wall is deformed due to congenital or age-associated pathological changes. The mechanisms of TAA development remain to be studied in detail, and are the subject of active research. In this review, we describe the morphological changes of the aortic wall in TAA. We outline the genetic disorders associated with aortic enlargement and discuss the potential role of mitochondrial pathology, in particular mitochondrial DNA heteroplasmy, in the disease pathogenesis.
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Affiliation(s)
- A. V. Suslov
- National Medical Research Center of Cardiology, Moscow 121552, Russia; (A.V.S.); (M.A.A.); (P.V.C.); (I.A.S.); (A.Y.P.)
- Department of Human Anatomy, First Moscow State Medical University (Sechenov University), Moscow 119435, Russia;
| | - M. A. Afanasyev
- National Medical Research Center of Cardiology, Moscow 121552, Russia; (A.V.S.); (M.A.A.); (P.V.C.); (I.A.S.); (A.Y.P.)
| | - P. A. Degtyarev
- Department of Human Anatomy, First Moscow State Medical University (Sechenov University), Moscow 119435, Russia;
| | - P. V. Chumachenko
- National Medical Research Center of Cardiology, Moscow 121552, Russia; (A.V.S.); (M.A.A.); (P.V.C.); (I.A.S.); (A.Y.P.)
| | - M. Bagheri Ekta
- Research Institute of Human Morphology, Moscow 117418, Russia; (M.B.E.); (V.A.K.)
| | - V. N. Sukhorukov
- National Medical Research Center of Cardiology, Moscow 121552, Russia; (A.V.S.); (M.A.A.); (P.V.C.); (I.A.S.); (A.Y.P.)
- Research Institute of Human Morphology, Moscow 117418, Russia; (M.B.E.); (V.A.K.)
| | - V. A. Khotina
- Research Institute of Human Morphology, Moscow 117418, Russia; (M.B.E.); (V.A.K.)
- Institute of General Pathology and Pathophysiology, Moscow 125315, Russia
| | - S.-F. Yet
- Institute of Cellular and System Medicine, National Health Research Institutes, 35 Keyan Road, Zhunan Town 35053, Taiwan;
| | - I. A. Sobenin
- National Medical Research Center of Cardiology, Moscow 121552, Russia; (A.V.S.); (M.A.A.); (P.V.C.); (I.A.S.); (A.Y.P.)
| | - A. Yu Postnov
- National Medical Research Center of Cardiology, Moscow 121552, Russia; (A.V.S.); (M.A.A.); (P.V.C.); (I.A.S.); (A.Y.P.)
- Research Institute of Human Morphology, Moscow 117418, Russia; (M.B.E.); (V.A.K.)
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10
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Xin Y, Li J, Wu W, Liu X. Mitofusin-2: A New Mediator of Pathological Cell Proliferation. Front Cell Dev Biol 2021; 9:647631. [PMID: 33869201 PMCID: PMC8049505 DOI: 10.3389/fcell.2021.647631] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 03/02/2021] [Indexed: 02/05/2023] Open
Abstract
Cell proliferation is an important cellular process for physiological tissue homeostasis and remodeling. The mechanisms of cell proliferation in response to pathological stresses are not fully understood. Mitochondria are highly dynamic organelles whose shape, number, and biological functions are modulated by mitochondrial dynamics, including fusion and fission. Mitofusin-2 (Mfn-2) is an essential GTPase-related mitochondrial dynamics protein for maintaining mitochondrial network and bioenergetics. A growing body of evidence indicates that Mfn-2 has a potential role in regulating cell proliferation in various cell types. Here we review these new functions of Mfn-2, highlighting its crucial role in several signaling pathways during the process of pathological cell proliferation. We conclude that Mfn-2 could be a new mediator of pathological cell proliferation and a potential therapeutic target.
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Affiliation(s)
- Yanguo Xin
- Department of Cardiology, West China Hospital, Sichuan University, Chengdu, China
| | - Junli Li
- Laboratory of Cardiovascular Diseases, Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu, China
| | - Wenchao Wu
- Laboratory of Cardiovascular Diseases, Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu, China
| | - Xiaojing Liu
- Department of Cardiology, West China Hospital, Sichuan University, Chengdu, China.,Laboratory of Cardiovascular Diseases, Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu, China
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11
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Lamade AM, Anthonymuthu TS, Hier ZE, Gao Y, Kagan VE, Bayır H. Mitochondrial damage & lipid signaling in traumatic brain injury. Exp Neurol 2020; 329:113307. [PMID: 32289317 DOI: 10.1016/j.expneurol.2020.113307] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 04/09/2020] [Accepted: 04/10/2020] [Indexed: 12/13/2022]
Abstract
Mitochondria are essential for neuronal function because they serve not only to sustain energy and redox homeostasis but also are harbingers of death. A dysregulated mitochondrial network can cascade until function is irreparably lost, dooming cells. TBI is most prevalent in the young and comes at significant personal and societal costs. Traumatic brain injury (TBI) triggers a biphasic and mechanistically heterogenous response and this mechanistic heterogeneity has made the development of standardized treatments challenging. The secondary phase of TBI injury evolves over hours and days after the initial insult, providing a window of opportunity for intervention. However, no FDA approved treatment for neuroprotection after TBI currently exists. With recent advances in detection techniques, there has been increasing recognition of the significance and roles of mitochondrial redox lipid signaling in both acute and chronic central nervous system (CNS) pathologies. Oxidized lipids and their downstream products result from and contribute to TBI pathogenesis. Therapies targeting the mitochondrial lipid composition and redox state show promise in experimental TBI and warrant further exploration. In this review, we provide 1) an overview for mitochondrial redox homeostasis with emphasis on glutathione metabolism, 2) the key mechanisms of TBI mitochondrial injury, 3) the pathways of mitochondria specific phospholipid cardiolipin oxidation, and 4) review the mechanisms of mitochondria quality control in TBI with consideration of the roles lipids play in this process.
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Affiliation(s)
- Andrew M Lamade
- Department of Critical Care Medicine, Safar Center for Resuscitation Research UPMC, Pittsburgh, PA, USA; Department of Environmental and Occupational Health, Center for Free Radical and Antioxidant Health, University of Pittsburgh, Pittsburgh, PA, USA; Children's Neuroscience Institute, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, USA
| | - Tamil S Anthonymuthu
- Department of Critical Care Medicine, Safar Center for Resuscitation Research UPMC, Pittsburgh, PA, USA; Department of Environmental and Occupational Health, Center for Free Radical and Antioxidant Health, University of Pittsburgh, Pittsburgh, PA, USA; Children's Neuroscience Institute, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, USA
| | - Zachary E Hier
- Department of Critical Care Medicine, Safar Center for Resuscitation Research UPMC, Pittsburgh, PA, USA; Department of Environmental and Occupational Health, Center for Free Radical and Antioxidant Health, University of Pittsburgh, Pittsburgh, PA, USA; Children's Neuroscience Institute, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, USA
| | - Yuan Gao
- Department of Critical Care Medicine, Safar Center for Resuscitation Research UPMC, Pittsburgh, PA, USA; Children's Neuroscience Institute, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, USA
| | - Valerian E Kagan
- Department of Environmental and Occupational Health, Center for Free Radical and Antioxidant Health, University of Pittsburgh, Pittsburgh, PA, USA; Children's Neuroscience Institute, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, USA; Institute for Regenerative Medicine, IM Sechenov First Moscow State Medical University, Russian Federation
| | - Hülya Bayır
- Department of Critical Care Medicine, Safar Center for Resuscitation Research UPMC, Pittsburgh, PA, USA; Department of Environmental and Occupational Health, Center for Free Radical and Antioxidant Health, University of Pittsburgh, Pittsburgh, PA, USA; Children's Neuroscience Institute, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, USA.
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12
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De Vecchis D, Brandner A, Baaden M, Cohen MM, Taly A. A Molecular Perspective on Mitochondrial Membrane Fusion: From the Key Players to Oligomerization and Tethering of Mitofusin. J Membr Biol 2019; 252:293-306. [PMID: 31485701 DOI: 10.1007/s00232-019-00089-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 08/14/2019] [Indexed: 12/29/2022]
Abstract
Mitochondria are dynamic organelles characterized by an ultrastructural organization which is essential in maintaining their quality control and ensuring functional efficiency. The complex mitochondrial network is the result of the two ongoing forces of fusion and fission of inner and outer membranes. Understanding the functional details of mitochondrial dynamics is physiologically relevant as perturbations of this delicate equilibrium have critical consequences and involved in several neurological disorders. Molecular actors involved in this process are large GTPases from the dynamin-related protein family. They catalyze nucleotide-dependent membrane remodeling and are widely conserved from bacteria to higher eukaryotes. Although structural characterization of different family members has contributed in understanding molecular mechanisms of mitochondrial dynamics in more detail, the complete structure of some members as well as the precise assembly of functional oligomers remains largely unknown. As increasing structural data become available, the domain modularity across the dynamin superfamily emerged as a foundation for transfering the knowledge towards less characterized members. In this review, we will first provide an overview of the main actors involved in mitochondrial dynamics. We then discuss recent example of computational methodologies for the study of mitofusin oligomers, and present how the usage of integrative modeling in conjunction with biochemical data can be an asset in progressing the still challenging field of membrane dynamics.
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Affiliation(s)
- Dario De Vecchis
- School of Medicine, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, LIGHT Building, Leeds, LS2 9JT, UK.
| | - Astrid Brandner
- CNRS, Université de Paris, UPR 9080, Laboratoire de Biochimie Théorique, 13 Rue Pierre et Marie Curie, 75005, Paris, France.,Institut de Biologie Physico-Chimique - Fondation Edmond de Rothschild, PSL Research University, Paris, France
| | - Marc Baaden
- CNRS, Université de Paris, UPR 9080, Laboratoire de Biochimie Théorique, 13 Rue Pierre et Marie Curie, 75005, Paris, France.,Institut de Biologie Physico-Chimique - Fondation Edmond de Rothschild, PSL Research University, Paris, France
| | - Mickael M Cohen
- Institut de Biologie Physico-Chimique - Fondation Edmond de Rothschild, PSL Research University, Paris, France.,Laboratoire de Biologie Cellulaire et Moléculaire des Eucaryotes, Sorbonne Université, CNRS, UMR 8226, Paris, France
| | - Antoine Taly
- CNRS, Université de Paris, UPR 9080, Laboratoire de Biochimie Théorique, 13 Rue Pierre et Marie Curie, 75005, Paris, France. .,Institut de Biologie Physico-Chimique - Fondation Edmond de Rothschild, PSL Research University, Paris, France.
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13
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Kou Y, He Y, Qiu J, Shu Y, Yang F, Deng Y, Naqvi NI. Mitochondrial dynamics and mitophagy are necessary for proper invasive growth in rice blast. MOLECULAR PLANT PATHOLOGY 2019; 20:1147-1162. [PMID: 31218796 PMCID: PMC6640187 DOI: 10.1111/mpp.12822] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Magnaporthe oryzae causes blast disease, which is one of the most devastating infections in rice and several important cereal crops. Magnaporthe oryzae needs to coordinate gene regulation, morphological changes, nutrient acquisition and host evasion in order to invade and proliferate within the plant tissues. Thus far, the molecular mechanisms underlying the regulation of invasive growth in planta have remained largely unknown. We identified a precise filamentous-punctate-filamentous cycle in mitochondrial morphology during Magnaporthe-rice interaction. Interestingly, disruption of such mitochondrial dynamics by deletion of genes regulating either the mitochondrial fusion (MoFzo1) or fission (MoDnm1) machinery, or inhibition of mitochondrial fission using Mdivi-1 caused significant reduction in M. oryzae pathogenicity. Furthermore, exogenous carbon source(s) but not antioxidant treatment delayed such mitochondrial dynamics/transition during invasive growth. In contrast, carbon starvation induced the breakdown of the mitochondrial network and led to more punctate mitochondria in vitro. Such nutrient-based regulation of organellar dynamics preceded MoAtg24-mediated mitophagy, which was found to be essential for proper biotrophic development and invasive growth in planta. We propose that precise mitochondrial dynamics and mitophagy occur during the transition from biotrophy to necrotrophy and are required for proper induction and establishment of the blast disease in rice.
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Affiliation(s)
- Yanjun Kou
- State Key Laboratory of Rice BiologyChina National Rice Research InstituteHangzhou311400China
| | - Yunlong He
- Temasek Life Sciences Laboratory, and Department of Biological Sciences, 1 Research LinkNational University of Singapore117604Singapore
| | - Jiehua Qiu
- State Key Laboratory of Rice BiologyChina National Rice Research InstituteHangzhou311400China
| | - Yazhou Shu
- State Key Laboratory of Rice BiologyChina National Rice Research InstituteHangzhou311400China
| | - Fan Yang
- Temasek Life Sciences Laboratory, and Department of Biological Sciences, 1 Research LinkNational University of Singapore117604Singapore
| | - YiZhen Deng
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research CentreSouth China Agricultural UniversityGuangzhou510642China
| | - Naweed I. Naqvi
- Temasek Life Sciences Laboratory, and Department of Biological Sciences, 1 Research LinkNational University of Singapore117604Singapore
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14
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Brandner A, De Vecchis D, Baaden M, Cohen MM, Taly A. Physics-based oligomeric models of the yeast mitofusin Fzo1 at the molecular scale in the context of membrane docking. Mitochondrion 2019; 49:234-244. [PMID: 31306768 DOI: 10.1016/j.mito.2019.06.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 06/07/2019] [Accepted: 06/24/2019] [Indexed: 11/17/2022]
Abstract
Tethering and homotypic fusion of mitochondrial outer membranes is mediated by large GTPases of the dynamin-related proteins family called the mitofusins. The yeast mitofusin Fzo1 forms high molecular weight complexes and its assembly during membrane fusion likely involves the formation of high order complexes. Consistent with this possibility, mitofusins form oligomers in both cis (on the same lipid bilayer) and trans to mediate membrane attachment and fusion. Here, we utilize our recent Fzo1 model to investigate and discuss the formation of cis and trans mitofusin oligomers. We have built three distinct cis-assembly Fzo1 models that gave rise to three distinct trans-oligomeric models of mitofusin constructs. Each model involves two main components of mitofusin oligomerization: the GTPase and the trunk domains. The oligomeric models proposed in this study were further assessed for stability and dynamics in a membrane environment using a coarse-grained molecular dynamics (MD) simulation approach. A narrow opening 'head-to-head' cis-oligomerization (via the GTPase domain) followed by the antiparallel 'back-to-back' trans-associations (via the trunk domain) appears to be in agreement with all of the available experimental data. More broadly, this study opens new possibilities to start exploring cis and trans conformations for Fzo1 and mitofusins in general.
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Affiliation(s)
- Astrid Brandner
- CNRS, Université de Paris, UPR 9080, Laboratoire de Biochimie Théorique, UPR 9080, 13 rue Pierre et Marie Curie, F-75005, Paris, France; Institut de Biologie Physico-Chimique-Fondation Edmond de Rothschild, PSL Research University, Paris, France
| | - Dario De Vecchis
- CNRS, Université de Paris, UPR 9080, Laboratoire de Biochimie Théorique, UPR 9080, 13 rue Pierre et Marie Curie, F-75005, Paris, France; Institut de Biologie Physico-Chimique-Fondation Edmond de Rothschild, PSL Research University, Paris, France
| | - Marc Baaden
- CNRS, Université de Paris, UPR 9080, Laboratoire de Biochimie Théorique, UPR 9080, 13 rue Pierre et Marie Curie, F-75005, Paris, France; Institut de Biologie Physico-Chimique-Fondation Edmond de Rothschild, PSL Research University, Paris, France
| | - Mickael M Cohen
- Laboratoire de Biologie Cellulaire et Moléculaire des Eucaryotes, Sorbonne Université, CNRS, UMR 8226, France; Institut de Biologie Physico-Chimique-Fondation Edmond de Rothschild, PSL Research University, Paris, France.
| | - Antoine Taly
- CNRS, Université de Paris, UPR 9080, Laboratoire de Biochimie Théorique, UPR 9080, 13 rue Pierre et Marie Curie, F-75005, Paris, France; Institut de Biologie Physico-Chimique-Fondation Edmond de Rothschild, PSL Research University, Paris, France.
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15
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Breda CNDS, Davanzo GG, Basso PJ, Saraiva Câmara NO, Moraes-Vieira PMM. Mitochondria as central hub of the immune system. Redox Biol 2019; 26:101255. [PMID: 31247505 PMCID: PMC6598836 DOI: 10.1016/j.redox.2019.101255] [Citation(s) in RCA: 174] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 06/01/2019] [Accepted: 06/10/2019] [Indexed: 02/08/2023] Open
Abstract
Nearly 130 years after the first insights into the existence of mitochondria, new rolesassociated with these organelles continue to emerge. As essential hubs that dictate cell fate, mitochondria integrate cell physiology, signaling pathways and metabolism. Thus, recent research has focused on understanding how these multifaceted functions can be used to improve inflammatory responses and prevent cellular dysfunction. Here, we describe the role of mitochondria on the development and function of immune cells, highlighting metabolic aspects and pointing out some metabolic- independent features of mitochondria that sustain cell function.
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Affiliation(s)
- Cristiane Naffah de Souza Breda
- Transplantation Immunobiology Lab, Department of Immunology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Gustavo Gastão Davanzo
- Laboratory of Immunometabolism, Department of Genetics, Evolution, Microbiology and Immunology, Institute of Biology, University of Campinas, Campinas, Brazil
| | - Paulo José Basso
- Transplantation Immunobiology Lab, Department of Immunology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Niels Olsen Saraiva Câmara
- Transplantation Immunobiology Lab, Department of Immunology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil.
| | - Pedro Manoel Mendes Moraes-Vieira
- Laboratory of Immunometabolism, Department of Genetics, Evolution, Microbiology and Immunology, Institute of Biology, University of Campinas, Campinas, Brazil.
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16
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Abstract
Mitochondria undergo frequent fusion and fission events to adapt their morphology to cellular needs. Homotypic docking and fusion of outer mitochondrial membranes are controlled by Mitofusins, a set of large membrane-anchored GTPase proteins belonging to the dynamin superfamily. Mitofusins include, in addition to their GTPase and transmembrane domains, two heptad repeat domains, HR1 and HR2. All four regions are crucial for Mitofusin function, but their precise contribution to mitochondrial docking and fusion events has remained elusive until very recently. In this commentary, we first give an overview of the established strategies employed by various protein machineries distinct from Mitofusins to mediate membrane fusion. We then present recent structure–function data on Mitofusins that provide important novel insights into their mode of action in mitochondrial fusion.
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Affiliation(s)
- Mickael M Cohen
- Sorbonne Université, CNRS UMR8226, Institut de Biologie Physico-Chimique, Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, Paris, France
| | - David Tareste
- Université Paris Descartes, Sorbonne Paris Cité, INSERM ERL U950, Trafic Membranaire dans le Cerveau Normal et Pathologique, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, INSERM UMR 894, Institut de Psychiatrie et Neurosciences de Paris, Paris, France
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17
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Maintenance of Mitochondrial Morphology in Cryptococcus neoformans Is Critical for Stress Resistance and Virulence. mBio 2018; 9:mBio.01375-18. [PMID: 30401774 PMCID: PMC6222134 DOI: 10.1128/mbio.01375-18] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
C. neoformans is a yeast that causes fatal brain infection in close to 200,000 people worldwide every year, mainly afflicting individuals with AIDS or others who are severely immunocompromised. One feature of this microbe that helps it cause disease is that it is able to withstand toxic molecules it encounters when host cells engulf it in their efforts to control the infection. Mitochondria are important organelles responsible for energy production and other key cellular processes. They typically exist in a complex network that changes morphology by fusing and dividing; these alterations also influence mitochondrial function. Using genetic approaches, we found that changes in mitochondrial morphology dramatically influence cryptococcal virulence. We showed that this occurs because the altered mitochondria are less able to eliminate the harmful molecules that host cells produce to kill invading microbes. These findings are important because they elucidate fundamental biology and virulence and may suggest avenues for therapy. Mitochondria are essential organelles that act in pathways including ATP production, β-oxidation, and clearance of reactive oxygen species. They occur as a complex reticular network that constantly undergoes fusion and fission, mediated by dynamin-related proteins (DRPs). DRPs include Fzo1, which mediates fusion, and Dnm1, Mdv1, and Fis1, which mediate fission. Mitochondrial morphology has been implicated in virulence in multiple fungi, as with the association between virulence and increased mitochondrial fusion in Cryptococcus gattii. This relationship, however, has not been studied in Cryptococcus neoformans, a related opportunistic pathogen. C. neoformans is an environmental yeast that can adapt to the human host environment, overcome the innate immune system, and eventually disseminate and cause lethal meningoencephalitis. We used gene deletion of key DRPs to study their role in mitochondrial morphology and pathogenesis of this yeast. Interestingly, increasing mitochondrial fusion did not increase resistance to oxidative stress, unlike in model yeast. Blocking mitochondrial fusion, however, yielded increased susceptibility to oxidative and nitrosative stresses as well as complete avirulence. This lack of virulence was not mediated by any effects of altered mitochondrial function on two major virulence factors, capsule and melanin. Instead, it was due to decreased survival within macrophages, which in turn was a consequence of increased susceptibility to oxidative and nitrosative stress. Supporting this conclusion, reactive oxygen species (ROS) scavengers rescued the ability of fusion mutants to survive intracellularly. These findings increase our understanding of cryptococcal biology and virulence and shed light on an important group of proteins and cellular processes in this pathogen.
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18
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Structural basis for membrane tethering by a bacterial dynamin-like pair. Nat Commun 2018; 9:3345. [PMID: 30131557 PMCID: PMC6104087 DOI: 10.1038/s41467-018-05523-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2018] [Accepted: 07/11/2018] [Indexed: 01/11/2023] Open
Abstract
Dynamin-like proteins (DLPs) are large GTPases that restructure membrane. DLPs such as the mitofusins form heterotypic oligomers between isoform pairs that bridge and fuse opposing membranes. In bacteria, heterotypic oligomerisation may also be important for membrane remodelling as most DLP genes are paired within operons. How DLPs tether opposing membranes is unknown. Here we show the crystal structure of a DLP heterotypic pair from the pathogen Campylobacter jejuni. A 2:2 stoichiometric tetramer is observed where heterodimers, conjoined by a random coil linker, assemble back-to-back to form a tripartite DLP chain with extreme flexibility. In vitro, tetramerisation triggers GTPase activity and induces lipid binding. Liposomes are readily tethered and form tubes at high tetramer concentration. Our results provide a direct mechanism for the long-range binding and bridging of opposing membranes by a bacterial DLP pair. They also provide broad mechanistic and structural insights that are relevant to other heterotypic DLP complexes. Dynamin-like proteins (DLPs) such as the mitofusins form homotypic and heterotypic oligomers that bridge and fuse opposing membranes. Here, Liu, Noel and Low present the crystal structure of a bacterial DLP heterotypic pair, providing insights into the mechanism behind long-range binding of opposing membranes.
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19
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Kar UP, Dey H, Rahaman A. Tetrahymena dynamin-related protein 6 self-assembles independent of membrane association. J Biosci 2018; 43:139-148. [PMID: 29485122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Self-assembly on target membranes is one of the important properties of all dynamin family proteins. Drp6, a dynaminrelated protein in Tetrahymena, controls nuclear remodelling and undergoes cycles of assembly/disassembly on the nuclear envelope. To elucidate the mechanism of Drp6 function, we have characterized its biochemical and biophysical properties using size exclusion chromatography, chemical cross-linking and electron microscopy. The results demonstrate that Drp6 readily forms high-molecular-weight self-assembled structures as determined by size exclusion chromatography and chemical cross-linking. Negative stain electron microscopy revealed that Drp6 assembles into rings and spirals at physiological ionic strength. We have also shown that the recombinant Drp6 expressed in bacteria is catalytically active and its GTPase activity is not enhanced by low salt. These results suggest that, in contrast to dynamins but similar to MxA, Drp6 self-assembles in the absence of membrane templates, and its GTPase activity is not affected by ionic strength of the buffer. We discuss the self-assembly structure of Drp6 and explain the basis for lack of membrane-stimulated GTPase activity.
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Affiliation(s)
- Usha P Kar
- School of Biological Sciences, National Institute of Science Education and Research-HBNI, Bhubaneswar, India
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20
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Kar UP, Dey H, Rahaman A. Tetrahymena dynamin-related protein 6 self-assembles independent of membrane association. J Biosci 2017. [DOI: 10.1007/s12038-017-9726-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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21
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Schorr S, van der Laan M. Integrative functions of the mitochondrial contact site and cristae organizing system. Semin Cell Dev Biol 2017; 76:191-200. [PMID: 28923515 DOI: 10.1016/j.semcdb.2017.09.021] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 09/13/2017] [Accepted: 09/14/2017] [Indexed: 12/23/2022]
Abstract
Mitochondria are complex double-membrane-bound organelles of eukaryotic cells that function as energy-converting powerhouses, metabolic factories and signaling centers. The outer membrane controls the exchange of material and information with other cellular compartments. The inner membrane provides an extended, highly folded surface for selective transport and energy-coupling reactions. It can be divided into an inner boundary membrane and tubular or lamellar cristae membranes that accommodate the oxidative phosphorylation units. Outer membrane, inner boundary membrane and cristae come together at crista junctions, where the mitochondrial contact site and cristae organizing system (MICOS) acts as a membrane-shaping and -connecting scaffold. This peculiar architecture is of pivotal importance for multiple mitochondrial functions. Many elaborate studies in the past years have shed light on the subunit composition and organization of MICOS. In this review article, we summarize these insights and then move on to discuss exciting recent discoveries on the integrative functions of MICOS. Multi-faceted connections to other major players of mitochondrial biogenesis and physiology, like the protein import machineries, the oxidative phosphorylation system, carrier proteins and phospholipid biosynthesis enzymes, are currently emerging. Therefore, we propose that MICOS acts as a central hub in mitochondrial membrane architecture and functionality.
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Affiliation(s)
- Stefan Schorr
- Medical Biochemistry and Molecular Biology, Center for Molecular Signaling, PZMS, Saarland University, School of Medicine, 66421, Homburg, Germany
| | - Martin van der Laan
- Medical Biochemistry and Molecular Biology, Center for Molecular Signaling, PZMS, Saarland University, School of Medicine, 66421, Homburg, Germany.
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22
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A membrane-inserted structural model of the yeast mitofusin Fzo1. Sci Rep 2017; 7:10217. [PMID: 28860650 PMCID: PMC5578988 DOI: 10.1038/s41598-017-10687-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 08/14/2017] [Indexed: 01/23/2023] Open
Abstract
Mitofusins are large transmembrane GTPases of the dynamin-related protein family, and are required for the tethering and fusion of mitochondrial outer membranes. Their full-length structures remain unknown, which is a limiting factor in the study of outer membrane fusion. We investigated the structure and dynamics of the yeast mitofusin Fzo1 through a hybrid computational and experimental approach, combining molecular modelling and all-atom molecular dynamics simulations in a lipid bilayer with site-directed mutagenesis and in vivo functional assays. The predicted architecture of Fzo1 improves upon the current domain annotation, with a precise description of the helical spans linked by flexible hinges, which are likely of functional significance. In vivo site-directed mutagenesis validates salient aspects of this model, notably, the long-distance contacts and residues participating in hinges. GDP is predicted to interact with Fzo1 through the G1 and G4 motifs of the GTPase domain. The model reveals structural determinants critical for protein function, including regions that may be involved in GTPase domain-dependent rearrangements.
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23
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Böckler S, Chelius X, Hock N, Klecker T, Wolter M, Weiss M, Braun RJ, Westermann B. Fusion, fission, and transport control asymmetric inheritance of mitochondria and protein aggregates. J Cell Biol 2017; 216:2481-2498. [PMID: 28615194 PMCID: PMC5551707 DOI: 10.1083/jcb.201611197] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 04/13/2017] [Accepted: 05/12/2017] [Indexed: 12/18/2022] Open
Abstract
Asymmetric inheritance of cell organelles determines the fate of daughter cells. Böckler et al. use yeast as a model to demonstrate that the dynamics of mitochondrial fusion, fission, and transport determine partitioning of mitochondria and cytosolic protein aggregates, which is critical for rejuvenation of daughter cells. Partitioning of cell organelles and cytoplasmic components determines the fate of daughter cells upon asymmetric division. We studied the role of mitochondria in this process using budding yeast as a model. Anterograde mitochondrial transport is mediated by the myosin motor, Myo2. A genetic screen revealed an unexpected interaction of MYO2 and genes required for mitochondrial fusion. Genetic analyses, live-cell microscopy, and simulations in silico showed that fused mitochondria become critical for inheritance and transport across the bud neck in myo2 mutants. Similarly, fused mitochondria are essential for retention in the mother when bud-directed transport is enforced. Inheritance of a less than critical mitochondrial quantity causes a severe decline of replicative life span of daughter cells. Myo2-dependent mitochondrial distribution also is critical for the capture of heat stress–induced cytosolic protein aggregates and their retention in the mother cell. Together, these data suggest that coordination of mitochondrial transport, fusion, and fission is critical for asymmetric division and rejuvenation of daughter cells.
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Affiliation(s)
| | - Xenia Chelius
- Zellbiologie, Universität Bayreuth, Bayreuth, Germany
| | - Nadine Hock
- Zellbiologie, Universität Bayreuth, Bayreuth, Germany
| | - Till Klecker
- Zellbiologie, Universität Bayreuth, Bayreuth, Germany
| | - Madita Wolter
- Zellbiologie, Universität Bayreuth, Bayreuth, Germany
| | - Matthias Weiss
- Experimentalphysik I, Universität Bayreuth, Bayreuth, Germany
| | - Ralf J Braun
- Zellbiologie, Universität Bayreuth, Bayreuth, Germany
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24
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Mitochondrial contact site and cristae organizing system: A central player in membrane shaping and crosstalk. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:1481-1489. [PMID: 28526561 DOI: 10.1016/j.bbamcr.2017.05.004] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 05/01/2017] [Indexed: 01/08/2023]
Abstract
Mitochondria are multifunctional metabolic factories and integrative signaling organelles of eukaryotic cells. The structural basis for their numerous functions is a complex and dynamic double-membrane architecture. The outer membrane connects mitochondria to the cytosol and other organelles. The inner membrane is composed of a boundary region and highly folded cristae membranes. The evolutionarily conserved mitochondrial contact site and cristae organizing system (MICOS) connects the two inner membrane domains via formation and stabilization of crista junction structures. Moreover, MICOS establishes contact sites between inner and outer mitochondrial membranes by interacting with outer membrane protein complexes. MICOS deficiency leads to a grossly altered inner membrane architecture resulting in far-reaching functional perturbations in mitochondria. Consequently, mutations affecting the function of MICOS are responsible for a diverse spectrum of human diseases. In this article, we summarize recent insights and concepts on the role of MICOS in the organization of mitochondrial membranes. This article is part of a Special Issue entitled: Membrane Contact Sites edited by Christian Ungermann and Benoit Kornmann.
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25
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Organelle Communication at Membrane Contact Sites (MCS): From Curiosity to Center Stage in Cell Biology and Biomedical Research. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 997:1-12. [DOI: 10.1007/978-981-10-4567-7_1] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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26
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Harner ME, Unger AK, Geerts WJ, Mari M, Izawa T, Stenger M, Geimer S, Reggiori F, Westermann B, Neupert W. An evidence based hypothesis on the existence of two pathways of mitochondrial crista formation. eLife 2016; 5. [PMID: 27849155 PMCID: PMC5138035 DOI: 10.7554/elife.18853] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 11/14/2016] [Indexed: 12/31/2022] Open
Abstract
Metabolic function and architecture of mitochondria are intimately linked. More than 60 years ago, cristae were discovered as characteristic elements of mitochondria that harbor the protein complexes of oxidative phosphorylation, but how cristae are formed, remained an open question. Here we present experimental results obtained with yeast that support a novel hypothesis on the existence of two molecular pathways that lead to the generation of lamellar and tubular cristae. Formation of lamellar cristae depends on the mitochondrial fusion machinery through a pathway that is required also for homeostasis of mitochondria and mitochondrial DNA. Tubular cristae are formed via invaginations of the inner boundary membrane by a pathway independent of the fusion machinery. Dimerization of the F1FO-ATP synthase and the presence of the MICOS complex are necessary for both pathways. The proposed hypothesis is suggested to apply also to higher eukaryotes, since the key components are conserved in structure and function throughout evolution. DOI:http://dx.doi.org/10.7554/eLife.18853.001 Cells contain compartments called mitochondria, which are often called the powerhouses of the cell because they provide energy that drives vital cellular processes. Mitochondria have two membranes: an outer and an inner membrane. The outer membrane separates the mitochondria from the rest of the cell. The inner membrane is elaborately folded and the folds – called cristae – create a larger space to accommodate all of the protein machinery involved in producing energy. The cristae can be shaped as flat sac-like structures called lamellar cristae or as tubes known as tubular cristae. Mitochondria are dynamic and are constantly fusing with other mitochondria and splitting up. Even though the internal architecture of mitochondria was first revealed around 60 years ago, it is still not clear how the cristae form. Harner et al. now address this question in yeast cells by combining imaging, biochemistry and genetic approaches. The experiments show that lamellar cristae form when two mitochondria fuse with each other. The outer membranes merge and then the inner membranes start to fuse around their edges to generate the sac-like structure of lamellar cristae. A yeast protein called Mgm1 (known as Opa1 in mammals) drives the fusion of the inner membranes, but this process only takes place when enzymes called F1FO-ATP synthases on the inner membrane form pairs with one another. These F1FO-ATP synthase pairs stabilize the cristae membranes as they curve to form the sac-like structure. Later on, the formation of a group of proteins called the MICOS complex halts the fusion process to prevent the lamellar cristae from completely separating from the rest of the inner membrane. Harner et al. also found that tubular cristae form using a different mechanism when the inner membrane of the mitochondria grows inwards. This process also requires pairs of F1FO-ATP synthases and the MICOS complex, but does not involve Mgm1/Opa1. Together, these findings show that lamellar and tubular cristae in yeast form using two different mechanisms. Since the key components of these mechanisms are also found in virtually all other eukaryotes, the findings of Harner et al. are also likely to apply to many other organisms including animals. DOI:http://dx.doi.org/10.7554/eLife.18853.002
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Affiliation(s)
- Max E Harner
- Max Planck Institute of Biochemistry, Martinsried, Germany.,Walter Brendel Centre of Experimental Medicine, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Ann-Katrin Unger
- Cell Biology and Electron Microscopy, Universität Bayreuth, Bayreuth, Germany
| | - Willie Jc Geerts
- Biomolecular Imaging, Bijvoet Center, Universiteit Utrecht, Utrecht, Netherlands
| | - Muriel Mari
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Toshiaki Izawa
- Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Maria Stenger
- Cell Biology and Electron Microscopy, Universität Bayreuth, Bayreuth, Germany
| | - Stefan Geimer
- Cell Biology and Electron Microscopy, Universität Bayreuth, Bayreuth, Germany
| | - Fulvio Reggiori
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Benedikt Westermann
- Cell Biology and Electron Microscopy, Universität Bayreuth, Bayreuth, Germany
| | - Walter Neupert
- Max Planck Institute of Biochemistry, Martinsried, Germany.,Department of Anatomy and Cell Biology, Biomedical Center, Ludwig-Maximilians Universität München, Martinsried, Germany
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27
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Patrushev MV, Mazunin IO, Vinogradova EN, Kamenski PA. Mitochondrial Fission and Fusion. BIOCHEMISTRY (MOSCOW) 2016; 80:1457-64. [PMID: 26615436 DOI: 10.1134/s0006297915110061] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Mitochondria are key cellular organelles responsible for many different functions. The molecular biology of mitochondria is continuously subject to comprehensive studies. However, detailed mechanisms of mitochondrial biogenesis are still unclear. Fusion and fission are among the most enigmatic processes connected with mitochondria. On the other hand, it has been shown that these events are of great biological importance for functioning of living cells. In this review, we summarize existing molecular data on mitochondrial dynamics and discuss possible biological functions of fusion and fission of these organelles.
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Affiliation(s)
- M V Patrushev
- Lomonosov Moscow State University, Faculty of Biology, Moscow, 119991, Russia.
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28
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Chien L, Chen WK, Liu ST, Chang CR, Kao MC, Chen KW, Chiu SC, Hsu ML, Hsiang IC, Chen YJ, Chen L. Low-dose ionizing radiation induces mitochondrial fusion and increases expression of mitochondrial complexes I and III in hippocampal neurons. Oncotarget 2016; 6:30628-39. [PMID: 26415228 PMCID: PMC4741557 DOI: 10.18632/oncotarget.5790] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Accepted: 09/07/2015] [Indexed: 11/25/2022] Open
Abstract
High energy ionizing radiation can cause DNA damage and cell death. During clinical radiation therapy, the radiation dose could range from 15 to 60 Gy depending on targets. While 2 Gy radiation has been shown to cause cancer cell death, studies also suggest a protective potential by low dose radiation. In this study, we examined the effect of 0.2-2 Gy radiation on hippocampal neurons. Low dose 0.2 Gy radiation treatment increased the levels of MTT. Since hippocampal neurons are post-mitotic, this result reveals a possibility that 0.2 Gy irradiation may increase mitochondrial activity to cope with stimuli. Maintaining neural plasticity is an energy-demanding process that requires high efficient mitochondrial function. We thus hypothesized that low dose radiation may regulate mitochondrial dynamics and function to ensure survival of neurons. Our results showed that five days after 0.2 Gy irradiation, no obvious changes on neuronal survival, neuronal synapses, membrane potential of mitochondria, reactive oxygen species levels, and mitochondrial DNA copy numbers. Interestingly, 0.2 Gy irradiation promoted the mitochondria fusion, resulting in part from the increased level of a mitochondrial fusion protein, Mfn2, and inhibition of Drp1 fission protein trafficking to the mitochondria. Accompanying with the increased mitochondrial fusion, the expressions of complexes I and III of the electron transport chain were also increased. These findings suggest that, hippocampal neurons undergo increased mitochondrial fusion to modulate cellular activity as an adaptive mechanism in response to low dose radiation.
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Affiliation(s)
- Ling Chien
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu, Taiwan, R.O.C
| | - Wun-Ke Chen
- Department of Radiation Oncology, MacKay Memorial Hospital, Taipei, Taiwan, R.O.C
| | - Szu-Ting Liu
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu, Taiwan, R.O.C
| | - Chuang-Rung Chang
- Department of Medical Science, National Tsing Hua University, Hsinchu, Taiwan, R.O.C.,Center for Brain Research, National Tsing Hua University, Hsinchu, Taiwan, R.O.C
| | - Mou-Chieh Kao
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu, Taiwan, R.O.C
| | - Kuan-Wei Chen
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu, Taiwan, R.O.C
| | - Shih-Che Chiu
- Department of Radiation Oncology, MacKay Memorial Hospital, Taipei, Taiwan, R.O.C
| | - Ming-Ling Hsu
- Department of Radiation Oncology, MacKay Memorial Hospital, Taipei, Taiwan, R.O.C
| | - I-Chou Hsiang
- Department of Radiation Oncology, MacKay Memorial Hospital, Taipei, Taiwan, R.O.C
| | - Yu-Jen Chen
- Department of Radiation Oncology, MacKay Memorial Hospital, Taipei, Taiwan, R.O.C
| | - Linyi Chen
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu, Taiwan, R.O.C.,Department of Medical Science, National Tsing Hua University, Hsinchu, Taiwan, R.O.C.,Center for Brain Research, National Tsing Hua University, Hsinchu, Taiwan, R.O.C
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A mutation in the THG1L gene in a family with cerebellar ataxia and developmental delay. Neurogenetics 2016; 17:219-225. [PMID: 27307223 DOI: 10.1007/s10048-016-0487-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 05/29/2016] [Indexed: 12/31/2022]
Abstract
Autosomal-recessive cerebellar atrophy is usually associated with inactivating mutations and early-onset presentation. The underlying molecular diagnosis suggests the involvement of neuronal survival pathways, but many mechanisms are still lacking and most patients elude genetic diagnosis. Using whole exome sequencing, we identified homozygous p.Val55Ala in the THG1L (tRNA-histidine guanylyltransferase 1 like) gene in three siblings who presented with cerebellar signs, developmental delay, dysarthria, and pyramidal signs and had cerebellar atrophy on brain MRI. THG1L protein was previously reported to participate in mitochondrial fusion via its interaction with MFN2. Abnormal mitochondrial fragmentation, including mitochondria accumulation around the nuclei and confinement of the mitochondrial network to the nuclear vicinity, was observed when patient fibroblasts were cultured in galactose containing medium. Culturing cells in galactose containing media promotes cellular respiration by oxidative phosphorylation and the action of the electron transport chain thus stimulating mitochondrial activity. The growth defect of the yeast thg1Δ strain was rescued by the expression of either yeast Thg1 or human THG1L; however, clear growth defect was observed following the expression of the human p.Val55Ala THG1L or the corresponding yeast mutant. A defect in the protein tRNAHis guanylyltransferase activity was excluded by the normal in vitro G-1 addition to either yeast tRNAHis or human mitochondrial tRNAHis in the presence of the THG1L mutation. We propose that homozygosity for the p.Val55Ala mutation in THG1L is the cause of the abnormal mitochondrial network in the patient fibroblasts, likely by interfering with THG1L activity towards MFN2. This may result in lack of mitochondria in the cerebellar Purkinje dendrites, with degeneration of Purkinje cell bodies and apoptosis of granule cells, as reported for MFN2 deficient mice.
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Genome-Wide Screens in Saccharomyces cerevisiae Highlight a Role for Cardiolipin in Biogenesis of Mitochondrial Outer Membrane Multispan Proteins. Mol Cell Biol 2015; 35:3200-11. [PMID: 26149385 DOI: 10.1128/mcb.00107-15] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 06/26/2015] [Indexed: 11/20/2022] Open
Abstract
A special group of mitochondrial outer membrane (MOM) proteins spans the membrane several times via multiple helical segments. Such multispan proteins are synthesized on cytosolic ribosomes before their targeting to mitochondria and insertion into the MOM. Previous work recognized the import receptor Tom70 and the mitochondrial import (MIM) complex, both residents of the MOM, as required for optimal biogenesis of these proteins. However, their involvement is not sufficient to explain either the entire import pathway or its regulation. To identify additional factors that are involved in the biogenesis of MOM multispan proteins, we performed complementary high-throughput visual and growth screens in Saccharomyces cerevisiae. Cardiolipin (CL) synthase (Crd1) appeared as a candidate in both screens. Our results indeed demonstrate lower steady-state levels of the multispan proteins Ugo1, Scm4, and Om14 in mitochondria from crd1Δ cells. Importantly, MOM single-span proteins were not affected by this mutation. Furthermore, organelles lacking Crd1 had a lower in vitro capacity to import newly synthesized Ugo1 and Scm4 molecules. Crd1, which is located in the mitochondrial inner membrane, condenses phosphatidylglycerol together with CDP-diacylglycerol to obtain de novo synthesized CL molecules. Hence, our findings suggest that CL is an important component in the biogenesis of MOM multispan proteins.
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Hickey FB, Corcoran JB, Griffin B, Bhreathnach U, Mortiboys H, Reid HM, Andrews D, Byrne S, Furlong F, Martin F, Godson C, Murphy M. IHG-1 increases mitochondrial fusion and bioenergetic function. Diabetes 2014; 63:4314-25. [PMID: 25008184 DOI: 10.2337/db13-1256] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Induced in high glucose-1 (IHG-1) is a conserved mitochondrial protein associated with diabetic nephropathy (DN) that amplifies profibrotic transforming growth factor (TGF)-β1 signaling and increases mitochondrial biogenesis. Here we report that inhibition of endogenous IHG-1 expression results in reduced mitochondrial respiratory capacity, ATP production, and mitochondrial fusion. Conversely, overexpression of IHG-1 leads to increased mitochondrial fusion and also protects cells from reactive oxygen species-induced apoptosis. IHG-1 forms complexes with known mediators of mitochondrial fusion-mitofusins (Mfns) 1 and 2-and enhances the GTP-binding capacity of Mfn2, suggesting that IHG-1 acts as a guanine nucleotide exchange factor. IHG-1 must be localized to mitochondria to interact with Mfn1 and Mfn2, and this interaction is necessary for increased IHG-1-mediated mitochondrial fusion. Together, these findings indicate that IHG-1 is a novel regulator of both mitochondrial dynamics and bioenergetic function and contributes to cell survival following oxidant stress. We propose that in diabetic kidney disease increased IHG-1 expression protects cell viability and enhances the actions of TGF-β, leading to renal proximal tubule dedifferentiation, an important event in the pathogenesis of this devastating condition.
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Affiliation(s)
- Fionnuala B Hickey
- Diabetes Complications Research Centre, Conway Institute, University College Dublin, Belfield, Dublin, Ireland School of Medicine and Medical Sciences, University College Dublin, Belfield, Dublin, Ireland Trinity Health Kidney Centre, Trinity College, Dublin, Ireland
| | - James B Corcoran
- Diabetes Complications Research Centre, Conway Institute, University College Dublin, Belfield, Dublin, Ireland School of Medicine and Medical Sciences, University College Dublin, Belfield, Dublin, Ireland
| | - Brenda Griffin
- Diabetes Complications Research Centre, Conway Institute, University College Dublin, Belfield, Dublin, Ireland School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin, Ireland
| | - Una Bhreathnach
- Diabetes Complications Research Centre, Conway Institute, University College Dublin, Belfield, Dublin, Ireland School of Medicine and Medical Sciences, University College Dublin, Belfield, Dublin, Ireland
| | - Heather Mortiboys
- Academic Neurology Unit, Medical School, University of Sheffield, Sheffield, U.K
| | - Helen M Reid
- School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin, Ireland
| | - Darrell Andrews
- Diabetes Complications Research Centre, Conway Institute, University College Dublin, Belfield, Dublin, Ireland School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin, Ireland
| | - Shane Byrne
- Diabetes Complications Research Centre, Conway Institute, University College Dublin, Belfield, Dublin, Ireland School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin, Ireland
| | - Fiona Furlong
- School of Pharmacy, Queen's University Belfast, Belfast, Northern Ireland
| | - Finian Martin
- Diabetes Complications Research Centre, Conway Institute, University College Dublin, Belfield, Dublin, Ireland School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin, Ireland
| | - Catherine Godson
- Diabetes Complications Research Centre, Conway Institute, University College Dublin, Belfield, Dublin, Ireland School of Medicine and Medical Sciences, University College Dublin, Belfield, Dublin, Ireland
| | - Madeline Murphy
- Diabetes Complications Research Centre, Conway Institute, University College Dublin, Belfield, Dublin, Ireland School of Medicine and Medical Sciences, University College Dublin, Belfield, Dublin, Ireland
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Harbauer AB, Opalińska M, Gerbeth C, Herman JS, Rao S, Schönfisch B, Guiard B, Schmidt O, Pfanner N, Meisinger C. Mitochondria. Cell cycle-dependent regulation of mitochondrial preprotein translocase. Science 2014; 346:1109-13. [PMID: 25378463 DOI: 10.1126/science.1261253] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mitochondria play central roles in cellular energy conversion, metabolism, and apoptosis. Mitochondria import more than 1000 different proteins from the cytosol. It is unknown if the mitochondrial protein import machinery is connected to the cell division cycle. We found that the cyclin-dependent kinase Cdk1 stimulated assembly of the main mitochondrial entry gate, the translocase of the outer membrane (TOM), in mitosis. The molecular mechanism involved phosphorylation of the cytosolic precursor of Tom6 by cyclin Clb3-activated Cdk1, leading to enhanced import of Tom6 into mitochondria. Tom6 phosphorylation promoted assembly of the protein import channel Tom40 and import of fusion proteins, thus stimulating the respiratory activity of mitochondria in mitosis. Tom6 phosphorylation provides a direct means for regulating mitochondrial biogenesis and activity in a cell cycle-specific manner.
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Affiliation(s)
- Angelika B Harbauer
- Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany. Trinationales Graduiertenkolleg 1478, Universität Freiburg, 79104 Freiburg, Germany. Faculty of Biology, Universität Freiburg, 79104 Freiburg, Germany. BIOSS Centre for Biological Signalling Studies, Universität Freiburg, 79104 Freiburg, Germany
| | - Magdalena Opalińska
- Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany
| | - Carolin Gerbeth
- Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany. Trinationales Graduiertenkolleg 1478, Universität Freiburg, 79104 Freiburg, Germany. Faculty of Biology, Universität Freiburg, 79104 Freiburg, Germany
| | - Josip S Herman
- Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany
| | - Sanjana Rao
- Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany. Faculty of Biology, Universität Freiburg, 79104 Freiburg, Germany. Spemann Graduate School of Biology and Medicine, Universität Freiburg, 79104 Freiburg, Germany
| | - Birgit Schönfisch
- Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany
| | - Bernard Guiard
- Centre de Génétique Moléculaire, CNRS, 91190 Gif-sur-Yvette, France
| | - Oliver Schmidt
- Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany. BIOSS Centre for Biological Signalling Studies, Universität Freiburg, 79104 Freiburg, Germany
| | - Nikolaus Pfanner
- Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany. BIOSS Centre for Biological Signalling Studies, Universität Freiburg, 79104 Freiburg, Germany.
| | - Chris Meisinger
- Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany. BIOSS Centre for Biological Signalling Studies, Universität Freiburg, 79104 Freiburg, Germany.
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33
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Troppens DM, Chu M, Holcombe LJ, Gleeson O, O'Gara F, Read ND, Morrissey JP. The bacterial secondary metabolite 2,4-diacetylphloroglucinol impairs mitochondrial function and affects calcium homeostasis in Neurospora crassa. Fungal Genet Biol 2013; 56:135-46. [PMID: 23624246 DOI: 10.1016/j.fgb.2013.04.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Revised: 03/25/2013] [Accepted: 04/12/2013] [Indexed: 10/26/2022]
Abstract
The bacterial secondary metabolite 2,4-diacetylphloroglucinol (DAPG) is of interest as an active ingredient of biological control strains of Pseudomonas fluorescens and as a potential lead pharmaceutical molecule because of its capacity to inhibit growth of diverse microbial and non-microbial cells. The mechanism by which this occurs is unknown and in this study the filamentous fungus Neurospora crassa was used as a model to investigate the effects of DAPG on a eukaryotic cell. Colony growth, conidial germination and cell fusion assays confirmed the inhibitory nature of DAPG towards N. crassa. A number of different fluorescent dyes and fluorescent protein reporters were used to assess the effects of DAPG treatment on mitochondrial and other cellular functions. DAPG treatment led to changes in mitochondrial morphology, and rapid loss of mitochondrial membrane potential. These effects are likely to be responsible for the toxicity of DAPG. It was also found that DAPG treatment caused extracellular calcium to be taken up by conidial germlings leading to a transient increase in cytosolic free Ca(2+) with a distinct concentration dependent Ca(2+) signature.
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34
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Escobar-Henriques M, Anton F. Mechanistic perspective of mitochondrial fusion: tubulation vs. fragmentation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:162-75. [PMID: 22884630 DOI: 10.1016/j.bbamcr.2012.07.016] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Revised: 07/28/2012] [Accepted: 07/30/2012] [Indexed: 01/02/2023]
Abstract
Mitochondrial fusion is a fundamental process driven by dynamin related GTPase proteins (DRPs), in contrast to the general SNARE-dependence of most cellular fusion events. The DRPs Mfn1/Mfn2/Fzo1 and OPA1/Mgm1 are the key effectors for fusion of the mitochondrial outer and inner membranes, respectively. In order to promote fusion, these two DRPs require post-translational modifications and proteolysis. OPA1/Mgm1 undergoes partial proteolytic processing, which results in a combination between short and long isoforms. In turn, ubiquitylation of mitofusins, after oligomerization and GTP hydrolysis, promotes and positively regulates mitochondrial fusion. In contrast, under conditions of mitochondrial dysfunction, negative regulation by proteolysis on these DRPs results in mitochondrial fragmentation. This occurs by complete processing of OPA1 and via ubiquitylation and degradation of mitofusins. Mitochondrial fragmentation contributes to the elimination of damaged mitochondria by mitophagy, and may play a protective role against Parkinson's disease. Moreover, a link of Mfn2 to Alzheimer's disease is emerging and mutations in Mfn2 or OPA1 cause Charcot-Marie-Tooth type 2A neuropathy or autosomal-dominant optic atrophy. Here, we summarize our current understanding on the molecular mechanisms promoting or inhibiting fusion of mitochondrial membranes, which is essential for cellular survival and disease control. This article is part of a Special Issue entitled: Mitochondrial dynamics and physiology.
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Zhao J, Lendahl U, Nistér M. Regulation of mitochondrial dynamics: convergences and divergences between yeast and vertebrates. Cell Mol Life Sci 2012; 70:951-76. [PMID: 22806564 PMCID: PMC3578726 DOI: 10.1007/s00018-012-1066-6] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 06/18/2012] [Accepted: 06/19/2012] [Indexed: 12/20/2022]
Abstract
In eukaryotic cells, the shape of mitochondria can be tuned to various physiological conditions by a balance of fusion and fission processes termed mitochondrial dynamics. Mitochondrial dynamics controls not only the morphology but also the function of mitochondria, and therefore is crucial in many aspects of a cell’s life. Consequently, dysfunction of mitochondrial dynamics has been implicated in a variety of human diseases including cancer. Several proteins important for mitochondrial fusion and fission have been discovered over the past decade. However, there is emerging evidence that there are as yet unidentified proteins important for these processes and that the fusion/fission machinery is not completely conserved between yeast and vertebrates. The recent characterization of several mammalian proteins important for the process that were not conserved in yeast, may indicate that the molecular mechanisms regulating and controlling the morphology and function of mitochondria are more elaborate and complex in vertebrates. This difference could possibly be a consequence of different needs in the different cell types of multicellular organisms. Here, we review recent advances in the field of mitochondrial dynamics. We highlight and discuss the mechanisms regulating recruitment of cytosolic Drp1 to the mitochondrial outer membrane by Fis1, Mff, and MIEF1 in mammals and the divergences in regulation of mitochondrial dynamics between yeast and vertebrates.
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Affiliation(s)
- Jian Zhao
- Department of Oncology-Pathology, Karolinska Institutet, CCK R8:05, Karolinska University Hospital Solna, 171 76, Stockholm, Sweden,
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Papanicolaou KN, Phillippo MM, Walsh K. Mitofusins and the mitochondrial permeability transition: the potential downside of mitochondrial fusion. Am J Physiol Heart Circ Physiol 2012; 303:H243-55. [PMID: 22636681 DOI: 10.1152/ajpheart.00185.2012] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Mitofusins (Mfn-1 and Mfn-2) are transmembrane proteins that bind and hydrolyze guanosine 5'-triphosphate to bring about the merging of adjacent mitochondrial membranes. This event is necessary for mitochondrial fusion, a biological process that is critical for organelle function. The broad effects of mitochondrial fusion on cell bioenergetics have been extensively studied, whereas the local effects of mitofusin activity on the structure and integrity of the fusing mitochondrial membranes have received relatively little attention. From the study of fusogenic proteins, theoretical models, and simulations, it has been noted that the fusion of biological membranes is associated with local perturbations on the integrity of the membrane that present in the form of lipidic holes which open on the opposing bilayers. These lipidic holes represent obligate intermediates that make the fusion process thermodynamically more favorable and at the same time induce leakage to the fusing membranes. In this perspectives article we present the relevant evidence selected from a spectrum of membrane fusion/leakage models and attempt to couple this information with observations conducted with cardiac myocytes or mitochondria deficient in Mfn-1 and Mfn-2. More specifically, we argue in favor of a situation whereby mitochondrial fusion in cardiac myocytes is coupled with outer mitochondrial membrane destabilization that is opportunistically employed during the process of mitochondrial permeability transition. We hope that these insights will initiate research on this new hypothesis of mitochondrial permeability transition regulation, a poorly understood mitochondrial function with significant consequences on myocyte survival.
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Affiliation(s)
- Kyriakos N Papanicolaou
- Whitaker Cardiovascular Institute, Boston University School of Medicine, Massachusetts, 02118, USA
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Tang WX, Wu WH, Zeng XX, Bo H, Huang SM. Early protective effect of mitofusion 2 overexpression in STZ-induced diabetic rat kidney. Endocrine 2012; 41:236-47. [PMID: 22095488 DOI: 10.1007/s12020-011-9555-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Accepted: 10/27/2011] [Indexed: 02/05/2023]
Abstract
Diabetic nephropathy (DN) is a serious complication of diabetes with a poorly defined etiology and limited treatment options. Early intervention is key to preventing the progression of DN. Mitofusin 2 (Mfn2) regulates mitochondrial morphology and signaling, and is involved in the pathogenesis of numerous diseases. Furthermore, Mfn2 is also closely associated with the development of diabetes, but its functional roles in the diabetic kidney remain unknown. This study investigated the effect of Mfn2 at an early stage of DN. Mfn2 was overexpressed by adenovirus-mediated gene transfer in streptozotocin-induced diabetic rats. Clinical parameters (proteinuria, albumin/creatinine ratio), pathological changes, ultra-microstructural changes in nephrons, expression of collagen IV and phosph-p38, ROS production, mitochondrial function, and apoptosis were evaluated and compared with diabetic rats expressing control levels of Mfn2. Endogenous Mfn2 expression decreased with time in DN. Compared to the blank transfection control group, overexpression of Mfn2 decreased kidney weight relative to body weight, reduced proteinuria and ACR, and improved pathological changes typical of the diabetic kidney, like enlargement of glomeruli, accumulation of ECM, and thickening of the basement membrane. In addition, Mfn2 overexpression inhibited activation of p38, and the accumulation of ROS; prevented mitochondrial dysfunction; and reduced the synthesis of collagen IV, but did not affect apoptosis of kidney cells. This study demonstrates that Mfn2 overexpression can attenuate pathological changes in the kidneys of diabetic rats. Further studies are needed to clarify the underlying mechanism of this protective function. Mfn2 might be a potential therapeutic target for the treatment of early stage DN.
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Affiliation(s)
- Wan Xin Tang
- Division of Nephrology, West China Hospital of Sichuan University, Chengdu, Sichuan, China.
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38
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Plafker SM, O'Mealey GB, Szweda LI. Mechanisms for countering oxidative stress and damage in retinal pigment epithelium. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 298:135-77. [PMID: 22878106 DOI: 10.1016/b978-0-12-394309-5.00004-3] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Clinical and experimental evidence supports that chronic oxidative stress is a primary contributing factor to numerous retinal degenerative diseases, such as age-related macular degeneration (AMD). Eyes obtained postmortem from AMD patients have extensive free radical damage to the proteins, lipids, DNA, and mitochondria of their retinal pigment epithelial (RPE) cells. In addition, several mouse models of chronic oxidative stress develop many of the pathological hallmarks of AMD. However, the extent to which oxidative stress is an etiologic component versus its involvement in disease progression remains a major unanswered question. Further, whether the primary target of oxidative stress and damage is photoreceptors or RPE cells, or both, is still unclear. In this review, we discuss the major functions of RPE cells with an emphasis on the oxidative challenges these cells encounter and the endogenous antioxidant mechanisms employed to neutralize the deleterious effects that such stresses can elicit if left unchecked.
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Affiliation(s)
- Scott M Plafker
- Free Radical Biology and Aging Program, Oklahoma Medical Research Foundation, Oklahoma City, USA
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39
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The mitochondrial contact site complex, a determinant of mitochondrial architecture. EMBO J 2011; 30:4356-70. [PMID: 22009199 DOI: 10.1038/emboj.2011.379] [Citation(s) in RCA: 348] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 09/29/2011] [Indexed: 11/08/2022] Open
Abstract
Mitochondria are organelles with a complex architecture. They are bounded by an envelope consisting of the outer membrane and the inner boundary membrane (IBM). Narrow crista junctions (CJs) link the IBM to the cristae. OMs and IBMs are firmly connected by contact sites (CS). The molecular nature of the CS remained unknown. Using quantitative high-resolution mass spectrometry we identified a novel complex, the mitochondrial contact site (MICOS) complex, formed by a set of mitochondrial membrane proteins that is essential for the formation of CS. MICOS is preferentially located at the CJs. Upon loss of one of the MICOS subunits, CJs disappear completely or are impaired, showing that CJs require the presence of CS to form a superstructure that links the IBM to the cristae. Loss of MICOS subunits results in loss of respiratory competence and altered inheritance of mitochondrial DNA.
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40
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Papic D, Krumpe K, Dukanovic J, Dimmer KS, Rapaport D. Multispan mitochondrial outer membrane protein Ugo1 follows a unique Mim1-dependent import pathway. ACTA ACUST UNITED AC 2011; 194:397-405. [PMID: 21825074 PMCID: PMC3153653 DOI: 10.1083/jcb.201102041] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The mitochondrial outer membrane (MOM) harbors several multispan proteins that execute various functions. Despite their importance, the mechanisms by which these proteins are recognized and inserted into the outer membrane remain largely unclear. In this paper, we address this issue using yeast mitochondria and the multispan protein Ugo1. Using a specific insertion assay and analysis by native gel electrophoresis, we show that the import receptor Tom70, but not its partner Tom20, is involved in the initial recognition of the Ugo1 precursor. Surprisingly, the import pore formed by the translocase of the outer membrane complex appears not to be required for the insertion process. Conversely, the multifunctional outer membrane protein mitochondrial import 1 (Mim1) plays a central role in mediating the insertion of Ugo1. Collectively, these results suggest that Ugo1 is inserted into the MOM by a novel pathway in which Tom70 and Mim1 contribute to the efficiency and selectivity of the process.
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Affiliation(s)
- Drazen Papic
- Interfaculty Institute of Biochemistry, University of Tübingen, Germany
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Ma H, May RC. Mitochondria and the regulation of hypervirulence in the fatal fungal outbreak on Vancouver Island. Virulence 2011; 1:197-201. [PMID: 21178442 DOI: 10.4161/viru.1.3.11053] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
In our recent paper, we demonstrated that the hypervirulence exhibited by a lineage of the fatal fungal pathogen Cryptococcus gattii is associated with its mitochondrial gene expression and an unusual mitochondrial morphology. As an important organelle, the mitochondrion has been linked to various cellular activities, but its role in modulating virulence of pathogens remains unclear. In this addendum, the potential role of mitochondria in determining virulence in eukaryotic pathogens is discussed along with future experiments that may lead to an improved understanding of this topic.
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Affiliation(s)
- Hansong Ma
- University of Birmingham, School of Biosciences, Edgbaston, Birmingham, West Midlands, UK
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Mendl N, Occhipinti A, Müller M, Wild P, Dikic I, Reichert AS. Mitophagy in yeast is independent of mitochondrial fission and requires the stress response gene WHI2. J Cell Sci 2011; 124:1339-50. [PMID: 21429936 DOI: 10.1242/jcs.076406] [Citation(s) in RCA: 134] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Dysfunctional mitochondria show a reduced capacity for fusion and, as mitochondrial fission is maintained, become spatially separated from the intact network. By that mechanism, dysfunctional mitochondria have been proposed to be targeted for selective degradation by mitophagy, thereby providing a quality control system for mitochondria. In yeast, conflicting results concerning the role of mitochondrial dynamics in mitophagy have been reported. Here, we investigate the effects on mitophagy of altering mitochondrial fission and fusion, using biochemical, as well as fluorescence-based, assays. Rapamycin-induced mitophagy was shown to depend upon the autophagy-related proteins Atg11, Atg20 and Atg24, confirming that a selective type of autophagy occurred. Both fragmentation of mitochondria and inhibition of oxidative phosphorylation were not sufficient to trigger mitophagy, and neither deletion of the fission factors Dnm1, Fis1, Mdv1 or Caf4 nor expression of dominant-negative variants of Dnm1 impaired mitophagy. The diminished mitophagy initially observed in a Δfis1 mutant was not due to the absence of Fis1 but rather due to a secondary mutation in WHI2, which encodes a factor reported to function in the general stress response and the Ras-protein kinase A (PKA) signaling pathway. We propose that, in yeast, mitochondrial fission is not a prerequisite for the selective degradation of mitochondria, and that mitophagy is linked to the general stress response and the Ras-PKA signaling pathway.
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Affiliation(s)
- Nadine Mendl
- Adolf-Butenandt-Institut für Physiologische Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5, 81377 München, Germany
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Dukanovic J, Rapaport D. Multiple pathways in the integration of proteins into the mitochondrial outer membrane. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:971-80. [DOI: 10.1016/j.bbamem.2010.06.021] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2010] [Revised: 06/22/2010] [Accepted: 06/23/2010] [Indexed: 11/25/2022]
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Guillet V, Gueguen N, Cartoni R, Chevrollier A, Desquiret V, Angebault C, Amati-Bonneau P, Procaccio V, Bonneau D, Martinou JC, Reynier P. Bioenergetic defect associated with mK
ATP
channel opening in a mouse model carrying a mitofusin 2 mutation. FASEB J 2011; 25:1618-27. [DOI: 10.1096/fj.10-173609] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Virginie Guillet
- Unité Mixte de Recherche (UMR) Centre National de la Recherche Scientifique (CNRS) 6214Institut National de la Santé et de la Recherche Médicale (INSERM) U771AngersFrance
- School of MedicineUniversity of AngersAngersFrance
- Department of Biochemistry and GeneticsUniversity Hospital of AngersAngersFrance
| | - Naïg Gueguen
- Unité Mixte de Recherche (UMR) Centre National de la Recherche Scientifique (CNRS) 6214Institut National de la Santé et de la Recherche Médicale (INSERM) U771AngersFrance
- Department of Biochemistry and GeneticsUniversity Hospital of AngersAngersFrance
| | - Romain Cartoni
- Department of Cell BiologyUniversity of GenevaGenevaSwitzerland
- F. M. Kirby Neurobiology CenterChildren's HospitalBostonMassachusettsUSA
- Department of NeurologyHarvard Medical SchoolBostonMassachusettsUSA
| | - Arnaud Chevrollier
- Unité Mixte de Recherche (UMR) Centre National de la Recherche Scientifique (CNRS) 6214Institut National de la Santé et de la Recherche Médicale (INSERM) U771AngersFrance
- Department of Biochemistry and GeneticsUniversity Hospital of AngersAngersFrance
| | - Valérie Desquiret
- Department of Biochemistry and GeneticsUniversity Hospital of AngersAngersFrance
| | - Claire Angebault
- Unité Mixte de Recherche (UMR) Centre National de la Recherche Scientifique (CNRS) 6214Institut National de la Santé et de la Recherche Médicale (INSERM) U771AngersFrance
- School of MedicineUniversity of AngersAngersFrance
| | - Patrizia Amati-Bonneau
- Unité Mixte de Recherche (UMR) Centre National de la Recherche Scientifique (CNRS) 6214Institut National de la Santé et de la Recherche Médicale (INSERM) U771AngersFrance
- Department of Biochemistry and GeneticsUniversity Hospital of AngersAngersFrance
| | - Vincent Procaccio
- Unité Mixte de Recherche (UMR) Centre National de la Recherche Scientifique (CNRS) 6214Institut National de la Santé et de la Recherche Médicale (INSERM) U771AngersFrance
- School of MedicineUniversity of AngersAngersFrance
- Department of Biochemistry and GeneticsUniversity Hospital of AngersAngersFrance
| | - Dominique Bonneau
- Unité Mixte de Recherche (UMR) Centre National de la Recherche Scientifique (CNRS) 6214Institut National de la Santé et de la Recherche Médicale (INSERM) U771AngersFrance
- School of MedicineUniversity of AngersAngersFrance
- Department of Biochemistry and GeneticsUniversity Hospital of AngersAngersFrance
| | | | - Pascal Reynier
- Unité Mixte de Recherche (UMR) Centre National de la Recherche Scientifique (CNRS) 6214Institut National de la Santé et de la Recherche Médicale (INSERM) U771AngersFrance
- School of MedicineUniversity of AngersAngersFrance
- Department of Biochemistry and GeneticsUniversity Hospital of AngersAngersFrance
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Abstract
Mitochondria are dynamic organelles that constantly fuse and divide. These processes (collectively termed mitochondrial dynamics) are important for mitochondrial inheritance and for the maintenance of mitochondrial functions. The core components of the evolutionarily conserved fusion and fission machineries have now been identified, and mechanistic studies have revealed the first secrets of the complex processes that govern fusion and fission of a double membrane-bound organelle. Mitochondrial dynamics was recently recognized as an important constituent of cellular quality control. Defects have detrimental consequences on bioenergetic supply and contribute to the pathogenesis of neurodegenerative diseases. These findings open exciting new directions to explore mitochondrial biology.
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Hammermeister M, Schödel K, Westermann B. Mdm36 is a mitochondrial fission-promoting protein in Saccharomyces cerevisiae. Mol Biol Cell 2010; 21:2443-52. [PMID: 20505073 PMCID: PMC2903673 DOI: 10.1091/mbc.e10-02-0096] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Mdm36 is a novel component of mitochondrial fission in yeast. Genetic and cytological approaches suggest that Mdm36 promotes the formation of attachment sites for mitochondria at the cell cortex. These Dnm1- and Num1-containing structures seem to be important for dynamin-mediated membrane fission and link mitochondrial motility and division. The division of mitochondrial membranes is a complex process mediated by the dynamin-related protein Dnm1 in yeast, acting in concert with several cofactors. We have identified Mdm36 as a mitochondria-associated protein required for efficient mitochondrial division. Δmdm36 mutants contain highly interconnected mitochondrial networks that strikingly resemble known fission mutants. Furthermore, mitochondrial fission induced by depolymerization of the actin cytoskeleton is blocked in Δmdm36 mutants, and the number of Dnm1 clusters on mitochondrial tips is reduced. Double mutant analyses indicate that Mdm36 acts antagonistically to fusion-promoting components, such as Fzo1 and Mdm30. The cell cortex-associated protein Num1 was shown previously to interact with Dnm1 and promote mitochondrial fission. We observed that mitochondria are highly motile and that their localization is not restricted to the cell periphery in Δmdm36 and Δnum1 mutants. Intriguingly, colocalization of Num1 and Dnm1 is abolished in the absence of Mdm36. These data suggest that Mdm36 is required for mitochondrial division by facilitating the formation of protein complexes containing Dnm1 and Num1 at the cell cortex. We propose a model that Mdm36-dependent formation of cell cortex anchors is required for the generation of tension on mitochondrial membranes to promote mitochondrial fission by Dnm1.
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Low HH, Sachse C, Amos LA, Löwe J. Structure of a bacterial dynamin-like protein lipid tube provides a mechanism for assembly and membrane curving. Cell 2010; 139:1342-52. [PMID: 20064379 PMCID: PMC2862293 DOI: 10.1016/j.cell.2009.11.003] [Citation(s) in RCA: 144] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Revised: 08/17/2009] [Accepted: 11/02/2009] [Indexed: 11/18/2022]
Abstract
Proteins of the dynamin superfamily mediate membrane fission, fusion, and restructuring events by polymerizing upon lipid bilayers and forcing regions of high curvature. In this work, we show the electron cryomicroscopy reconstruction of a bacterial dynamin-like protein (BDLP) helical filament decorating a lipid tube at ∼11 Å resolution. We fitted the BDLP crystal structure and produced a molecular model for the entire filament. The BDLP GTPase domain dimerizes and forms the tube surface, the GTPase effector domain (GED) mediates self-assembly, and the paddle region contacts the lipids and promotes curvature. Association of BDLP with GMPPNP and lipid induces radical, large-scale conformational changes affecting polymerization. Nucleotide hydrolysis seems therefore to be coupled to polymer disassembly and dissociation from lipid, rather than membrane restructuring. Observed structural similarities with rat dynamin 1 suggest that our results have broad implication for other dynamin family members.
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Affiliation(s)
- Harry H. Low
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
- Corresponding author
| | - Carsten Sachse
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
| | - Linda A. Amos
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
| | - Jan Löwe
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
- Corresponding author
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Schäfer A, Reichert AS. Emerging roles of mitochondrial membrane dynamics in health and disease. Biol Chem 2009; 390:707-15. [PMID: 19453275 DOI: 10.1515/bc.2009.086] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Mitochondria are highly dynamic organelles forming a tubular network that is sustained by fusion and fission events. Impairment thereof leads to various neuropathies in humans, such as optic atrophy and Parkinson's disease. We have only begun to understand the molecular machineries facilitating fusion and fission of mitochondria and how these processes are regulated. The physiological role of mitochondrial dynamics and how it may be involved in maintaining mitochondrial functionality is still unclear. Here, we discuss current views in this emerging field focusing on the molecular basis of how mitochondrial morphology is regulated and how this may contribute to mitochondrial quality control.
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Affiliation(s)
- Anja Schäfer
- CEF Makromolekulare Komplexe, Mitochondriale Biologie, Fachbereich Medizin, Goethe-Universität Frankfurt am Main, Theodor-Stern-Kai 7, D-60590 Frankfurt/Main, Germany
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Jourdain I, Gachet Y, Hyams JS. The dynamin related protein Dnm1 fragments mitochondria in a microtubule-dependent manner during the fission yeast cell cycle. ACTA ACUST UNITED AC 2009; 66:509-23. [PMID: 19373772 DOI: 10.1002/cm.20351] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Mitochondria are dynamic organelles that undergo cycles of fission and fusion. In the fission yeast, Schizosaccharomyces pombe, mitochondria align with microtubules and mitochondrial integrity is dependent upon an intact microtubule cytoskeleton. Here we show that mitochondria re-organize during the cell cycle and that this process is both dynamin- and microtubule-dependent. Microtubule depolymerization results in mitochondrial fragmentation but only when the dynamin-related protein Dnm1 is present. Mitochondrial fusion is, on the other hand, microtubule-independent. dnm1Delta cells, besides showing extensively fused mitochondria, are specifically resistant to anti-microtubule drugs. Dnm1-YFP localizes to foci at sites of mitochondrial severing which occupy the interface between adjacent nucleoids, suggesting the existence of defined mitochondrial "territories," each of which contains a nucleoid. Such territories are lost in dnm1Delta in which nucleoids become aggregated. Mitochondrial ends exhibit motile behavior, extending towards and retracting from the cell poles, independently of the cytoskeleton. We conclude that: (a) mitochondria are organized by microtubules in fission yeast but are not moved by them; (b) Dnm1 mediates mitochondrial fission during interphasic growth and at cell division; (c) the interaction between microtubules and mitochondria, either directly or indirectly via Dnm1, not only modifies the disposition of mitochondria it also modifies the behavior of microtubules. Cell Motil. Cytoskeleton 2009. (c) 2009 Wiley-Liss, Inc.
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Affiliation(s)
- Isabelle Jourdain
- Institute of Molecular Biosciences, Massey University, Private Bag 11 222, Palmerston North, New Zealand
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50
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Multidimensional quantification of subcellular morphology of Saccharomyces cerevisiae using CalMorph, the high-throughput image-processing program. J Biotechnol 2009; 141:109-17. [DOI: 10.1016/j.jbiotec.2009.03.014] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2009] [Revised: 03/12/2009] [Accepted: 03/20/2009] [Indexed: 11/19/2022]
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