401
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Abstract
Membrane contact sites between mitochondria and other organelles are important for lipid and ion exchange, membrane dynamics, and signaling. Recent advances are revealing their molecular features and how different types of mitochondria contacts are coordinated with each other for cell function.
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Affiliation(s)
- Andrew Murley
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA
| | - Jodi Nunnari
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA.
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402
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Abstract
Mitochondrial architecture is involved in several functions crucial for cell viability, proliferation, senescence, and signaling. In particular, mitochondrial dynamics, through the balance between fusion and fission events, represents a central mechanism for bioenergetic adaptation to metabolic needs of the cell. As key regulators of mitochondrial dynamics, the fusogenic mitofusins have recently been linked to mitochondrial biogenesis and respiratory functions, impacting on cell fate and organism homeostasis. Here we review the implication of mitofusins in the regulation of mitochondrial metabolism, and their consequence on energy homeostasis at the cellular and physiological level, highlighting their crucial role in metabolic disorders, cancer, and aging.
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403
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Agostini M, Fasolato C. When, where and how? Focus on neuronal calcium dysfunctions in Alzheimer's Disease. Cell Calcium 2016; 60:289-298. [PMID: 27451385 DOI: 10.1016/j.ceca.2016.06.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 06/27/2016] [Accepted: 06/28/2016] [Indexed: 02/06/2023]
Abstract
Alzheimer's disease (AD), since its characterization as a precise form of dementia with its own pathological hallmarks, has captured scientists' attention because of its complexity. The last 30 years have been filled with discoveries regarding the elusive aetiology of this disease and, thanks to advances in molecular biology and live imaging techniques, we now know that an important role is played by calcium (Ca2+). Ca2+, as ubiquitous second messenger, regulates a vast variety of cellular processes, from neuronal excitation and communication, to muscle fibre contraction and hormone secretion, with its action spanning a temporal scale that goes from microseconds to hours. It is therefore very challenging to conceive a single hypothesis that can integrate the numerous findings on this issue with those coming from the classical fields of AD research such as amyloid-beta (Aβ) and tau pathology. In this contribution, we will focus our attention on the Ca2+ hypothesis of AD, dissecting it, as much as possible, in its subcellular localization, where the Ca2+ signal meets its specificity. We will also follow the temporal evolution of the Ca2+ hypothesis, providing some of the most updated discoveries. Whenever possible, we will link the findings regarding Ca2+ dysfunction to the other players involved in AD pathogenesis, hoping to provide a crossover body of evidence, useful to amplify the knowledge that will lead towards the discovery of an effective therapy.
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Affiliation(s)
- Mario Agostini
- Department of Biomedical Sciences, University of Padua, Italy.
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404
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Giacomello M, Pellegrini L. The coming of age of the mitochondria-ER contact: a matter of thickness. Cell Death Differ 2016; 23:1417-27. [PMID: 27341186 DOI: 10.1038/cdd.2016.52] [Citation(s) in RCA: 278] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 05/02/2016] [Accepted: 05/05/2016] [Indexed: 12/12/2022] Open
Abstract
The sites of near-contact between the mitochondrion and the endoplasmic reticulum (ER) have earned a lot of attention due to their key role in the maintenance of lipid and calcium (Ca(2+)) homeostasis, in the initiation of autophagy and mitochondrial division, and in sensing metabolic shifts. At these sites, typically called MAMs (mitochondria-associated ER membranes) or MERCs (mitochondria-ER contacts), the organelles juxtapose at a distance that can range from ~10 to ~50 nm. The multifunctional role of this subcellular compartment is puzzling; further, recent studies have shown that mitochondria-ER contacts are highly plastic structures that remodel upon metabolic transitions and that their activity in controlling lipid homeostasis could be involved in Alzheimer's disease pathogenesis. This review aims at integrating the functions of this subcellular compartment to its most characterizing and unexplored structural parameter, their 'thickness': that is, the width of the cleft that separates the cytosolic face of the outer mitochondrial membrane from that of the ER. We describe and discuss the reasons why the thickness of a MERC should be considered a regulated structural parameter of the cell that defines and controls its function. Further, we propose a MERC classification that will help organize the expanding field of MERCs biology and of their role in cell physiology and human disease.
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Affiliation(s)
- M Giacomello
- Department of Biology, Università di Padova, Padua, Italy.,Venetian Institute of Molecular Medicine, Padua, Italy
| | - L Pellegrini
- Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine, Universitè Laval, Quebec, Québec, Canada.,Mitochondria Biology Laboratory, CRIUSMQ, Quebec, Québec, Canada
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405
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Interplay between hepatic mitochondria-associated membranes, lipid metabolism and caveolin-1 in mice. Sci Rep 2016; 6:27351. [PMID: 27272971 PMCID: PMC4894368 DOI: 10.1038/srep27351] [Citation(s) in RCA: 132] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 05/13/2016] [Indexed: 02/07/2023] Open
Abstract
The mitochondria-associated membrane (MAM) is a specialized subdomain of the endoplasmic reticulum (ER) which acts as an intracellular signaling hub. MAM dysfunction has been related to liver disease. We report a high-throughput mass spectrometry-based proteomics characterization of MAMs from mouse liver, which portrays them as an extremely complex compartment involved in different metabolic processes, including steroid metabolism. Interestingly, we identified caveolin-1 (CAV1) as an integral component of hepatic MAMs, which determine the relative cholesterol content of these ER subdomains. Finally, a detailed comparative proteomics analysis between MAMs from wild type and CAV1-deficient mice suggests that functional CAV1 contributes to the recruitment and regulation of intracellular steroid and lipoprotein metabolism-related processes accrued at MAMs. The potential impact of these novel aspects of CAV1 biology on global cell homeostasis and disease is discussed.
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406
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Filadi R, Greotti E, Turacchio G, Luini A, Pozzan T, Pizzo P. Presenilin 2 Modulates Endoplasmic Reticulum-Mitochondria Coupling by Tuning the Antagonistic Effect of Mitofusin 2. Cell Rep 2016; 15:2226-2238. [PMID: 27239030 DOI: 10.1016/j.celrep.2016.05.013] [Citation(s) in RCA: 119] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 03/23/2016] [Accepted: 04/28/2016] [Indexed: 01/31/2023] Open
Abstract
Communication between organelles plays key roles in cell biology. In particular, physical and functional coupling of the endoplasmic reticulum (ER) and mitochondria is crucial for regulation of various physiological and pathophysiological processes. Here, we demonstrate that Presenilin 2 (PS2), mutations in which underlie familial Alzheimer's disease (FAD), promotes ER-mitochondria coupling only in the presence of mitofusin 2 (Mfn2). PS2 is not necessary for the antagonistic effect of Mfn2 on organelle coupling, although its abundance can tune it. The two proteins physically interact, whereas their homologues Mfn1 and PS1 are dispensable for this interplay. Moreover, PS2 mutants associated with FAD are more effective than the wild-type form in modulating ER-mitochondria tethering because their binding to Mfn2 in mitochondria-associated membranes is favored. We propose a revised model for ER-mitochondria interaction to account for these findings and discuss possible implications for FAD pathogenesis.
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Affiliation(s)
- Riccardo Filadi
- Department of Biomedical Sciences, University of Padua, via U. Bassi 58/B, Padua 35131, Italy
| | - Elisa Greotti
- Department of Biomedical Sciences, University of Padua, via U. Bassi 58/B, Padua 35131, Italy; Department of Biomedical Sciences, Institute of Neuroscience, Italian National Research Council (CNR), via U. Bassi 58/B, Padua 35131, Italy
| | - Gabriele Turacchio
- Department of Biomedical Sciences, Institute of Protein Biochemistry, Italian National Research Council (CNR), via P. Castellino 111, Naples 80131, Italy
| | - Alberto Luini
- Department of Biomedical Sciences, Institute of Protein Biochemistry, Italian National Research Council (CNR), via P. Castellino 111, Naples 80131, Italy
| | - Tullio Pozzan
- Department of Biomedical Sciences, University of Padua, via U. Bassi 58/B, Padua 35131, Italy; Venetian Institute of Molecular Medicine, via Orus 2, Padua 35131, Italy; Department of Biomedical Sciences, Institute of Neuroscience, Italian National Research Council (CNR), via U. Bassi 58/B, Padua 35131, Italy
| | - Paola Pizzo
- Department of Biomedical Sciences, University of Padua, via U. Bassi 58/B, Padua 35131, Italy.
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407
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Leal NS, Schreiner B, Pinho CM, Filadi R, Wiehager B, Karlström H, Pizzo P, Ankarcrona M. Mitofusin-2 knockdown increases ER-mitochondria contact and decreases amyloid β-peptide production. J Cell Mol Med 2016; 20:1686-95. [PMID: 27203684 PMCID: PMC4988279 DOI: 10.1111/jcmm.12863] [Citation(s) in RCA: 120] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 03/04/2016] [Indexed: 12/28/2022] Open
Abstract
Mitochondria are physically and biochemically in contact with other organelles including the endoplasmic reticulum (ER). Such contacts are formed between mitochondria‐associated ER membranes (MAM), specialized subregions of ER, and the outer mitochondrial membrane (OMM). We have previously shown increased expression of MAM‐associated proteins and enhanced ER to mitochondria Ca2+ transfer from ER to mitochondria in Alzheimer's disease (AD) and amyloid β‐peptide (Aβ)‐related neuronal models. Here, we report that siRNA knockdown of mitofusin‐2 (Mfn2), a protein that is involved in the tethering of ER and mitochondria, leads to increased contact between the two organelles. Cells depleted in Mfn2 showed increased Ca2+ transfer from ER to mitchondria and longer stretches of ER forming contacts with OMM. Interestingly, increased contact resulted in decreased concentrations of intra‐ and extracellular Aβ40 and Aβ42. Analysis of γ‐secretase protein expression, maturation and activity revealed that the low Aβ concentrations were a result of impaired γ‐secretase complex function. Amyloid‐β precursor protein (APP), β‐site APP‐cleaving enzyme 1 and neprilysin expression as well as neprilysin activity were not affected by Mfn2 siRNA treatment. In summary, our data shows that modulation of ER–mitochondria contact affects γ‐secretase activity and Aβ generation. Increased ER–mitochondria contact results in lower γ‐secretase activity suggesting a new mechanism by which Aβ generation can be controlled.
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Affiliation(s)
- Nuno Santos Leal
- Center for Alzheimer Research, Division of Neurogeriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
| | - Bernadette Schreiner
- Center for Alzheimer Research, Division of Neurogeriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
| | - Catarina Moreira Pinho
- Center for Alzheimer Research, Division of Neurogeriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
| | - Riccardo Filadi
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Birgitta Wiehager
- Center for Alzheimer Research, Division of Neurogeriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
| | - Helena Karlström
- Center for Alzheimer Research, Division of Neurogeriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
| | - Paola Pizzo
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Maria Ankarcrona
- Center for Alzheimer Research, Division of Neurogeriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
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408
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Gautier CA, Erpapazoglou Z, Mouton-Liger F, Muriel MP, Cormier F, Bigou S, Duffaure S, Girard M, Foret B, Iannielli A, Broccoli V, Dalle C, Bohl D, Michel PP, Corvol JC, Brice A, Corti O. The endoplasmic reticulum-mitochondria interface is perturbed in PARK2 knockout mice and patients with PARK2 mutations. Hum Mol Genet 2016; 25:2972-2984. [PMID: 27206984 DOI: 10.1093/hmg/ddw148] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Revised: 05/10/2016] [Accepted: 05/10/2016] [Indexed: 12/13/2022] Open
Abstract
Mutations in PARK2, encoding the E3 ubiquitin protein ligase Parkin, are a common cause of autosomal recessive Parkinson's disease (PD). Loss of PARK2 function compromises mitochondrial quality by affecting mitochondrial biogenesis, bioenergetics, dynamics, transport and turnover. We investigated the impact of PARK2 dysfunction on the endoplasmic reticulum (ER)-mitochondria interface, which mediates calcium (Ca2+) exchange between the two compartments and is essential for Parkin-dependent mitophagy. Confocal and electron microscopy analyses showed the ER and mitochondria to be in closer proximity in primary fibroblasts from PARK2 knockout (KO) mice and PD patients with PARK2 mutations than in controls. Ca2+ flux to the cytosol was also modified, due to enhanced ER-to-mitochondria Ca2+ transfers, a change that was also observed in neurons derived from induced pluripotent stem cells of a patient with PARK2 mutations. Subcellular fractionation showed the abundance of the Parkin substrate mitofusin 2 (Mfn2), which is known to modulate the ER-mitochondria interface, to be specifically higher in the mitochondrion-associated ER membrane compartment in PARK2 KO tissue. Mfn2 downregulation or the exogenous expression of normal Parkin restored cytosolic Ca2+ transients in fibroblasts from patients with PARK2 mutations. In contrast, a catalytically inactive PD-related Parkin variant had no effect. Overall, our data suggest that Parkin is directly involved in regulating ER-mitochondria contacts and provide new insight into the role of the loss of Parkin function in PD development.
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Affiliation(s)
- Clément A Gautier
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Inserm, U1127, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, CNRS, UMR 7225, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France
| | - Zoi Erpapazoglou
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Inserm, U1127, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, CNRS, UMR 7225, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France
| | - François Mouton-Liger
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Inserm, U1127, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, CNRS, UMR 7225, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France
| | - Marie Paule Muriel
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Inserm, U1127, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, CNRS, UMR 7225, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France
| | - Florence Cormier
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Inserm, U1127, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, CNRS, UMR 7225, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France
- National Research Council (CNR), Institute of Neuroscience, Milan, Italy
| | - Stéphanie Bigou
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Inserm, U1127, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, CNRS, UMR 7225, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France
| | - Sophie Duffaure
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Inserm, U1127, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, CNRS, UMR 7225, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France
| | - Mathilde Girard
- CECS, I-Stem, AFM, Institute of Stem Cell Therapy and Exploration of Monogenic Diseases, 91030 Evry cedex, France
| | - Benjamin Foret
- CECS, I-Stem, AFM, Institute of Stem Cell Therapy and Exploration of Monogenic Diseases, 91030 Evry cedex, France
| | - Angelo Iannielli
- National Research Council (CNR), Institute of Neuroscience, Milan, Italy
- Division of Neuroscience, San Raffaele Scientific Institute, 20132 Milan, Italy
| | - Vania Broccoli
- National Research Council (CNR), Institute of Neuroscience, Milan, Italy
- Division of Neuroscience, San Raffaele Scientific Institute, 20132 Milan, Italy
| | - Carine Dalle
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Inserm, U1127, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, CNRS, UMR 7225, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France
| | - Delphine Bohl
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Inserm, U1127, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, CNRS, UMR 7225, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France
| | - Patrick P Michel
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Inserm, U1127, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, CNRS, UMR 7225, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France
| | - Jean-Christophe Corvol
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Inserm, U1127, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, CNRS, UMR 7225, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France
- Assistance-publique Hôpitaux de Paris, Inserm, CIC-1422, Department of Neurology, Hôpital Pitié-Salpêtrière, F-75013 Paris, France
| | - Alexis Brice
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Inserm, U1127, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, CNRS, UMR 7225, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France
| | - Olga Corti
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Inserm, U1127, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, CNRS, UMR 7225, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France
- Bases moléculaires, physiopathologie et traitement des maladies neurodégénératives, Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France
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409
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Okeke E, Dingsdale H, Parker T, Voronina S, Tepikin AV. Endoplasmic reticulum-plasma membrane junctions: structure, function and dynamics. J Physiol 2016; 594:2837-47. [PMID: 26939537 DOI: 10.1113/jp271142] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 02/13/2016] [Indexed: 12/20/2022] Open
Abstract
Endoplasmic reticulum (ER)-plasma membrane (PM) junctions are contact sites between the ER and the PM; the distance between the two organelles in the junctions is below 40 nm and the membranes are connected by protein tethers. A number of molecular tools and technical approaches have been recently developed to visualise, modify and characterise properties of ER-PM junctions. The junctions serve as the platforms for lipid exchange between the organelles and for cell signalling, notably Ca(2+) and cAMP signalling. Vice versa, signalling events regulate the development and properties of the junctions. Two Ca(2+) -dependent mechanisms of de novo formation of ER-PM junctions have been recently described and characterised. The junction-forming proteins and lipids are currently the focus of vigorous investigation. Junctions can be relatively short-lived and simple structures, forming and dissolving on the time scale of a few minutes. However, complex, sophisticated and multifunctional ER-PM junctions, capable of attracting numerous protein residents and other cellular organelles, have been described in some cell types. The road from simplicity to complexity, i.e. the transformation from simple 'nascent' ER-PM junctions to advanced stable multiorganellar complexes, is likely to become an attractive research avenue for current and future junctologists. Another area of considerable research interest is the downstream cellular processes that can be activated by specific local signalling events in the ER-PM junctions. Studies of the cell physiology and indeed pathophysiology of ER-PM junctions have already produced some surprising discoveries, likely to expand with advances in our understanding of these remarkable organellar contact sites.
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Affiliation(s)
- Emmanuel Okeke
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool, L69 3BX, UK
| | - Hayley Dingsdale
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool, L69 3BX, UK
| | - Tony Parker
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool, L69 3BX, UK
| | - Svetlana Voronina
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool, L69 3BX, UK
| | - Alexei V Tepikin
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool, L69 3BX, UK
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410
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La Rovere RML, Roest G, Bultynck G, Parys JB. Intracellular Ca(2+) signaling and Ca(2+) microdomains in the control of cell survival, apoptosis and autophagy. Cell Calcium 2016; 60:74-87. [PMID: 27157108 DOI: 10.1016/j.ceca.2016.04.005] [Citation(s) in RCA: 192] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2016] [Revised: 04/14/2016] [Accepted: 04/15/2016] [Indexed: 01/01/2023]
Abstract
The endoplasmic reticulum (ER), mitochondria and lysosomes are physically and/or functionally linked, establishing close contact sites between these organelles. As a consequence, Ca(2+) release events from the ER, the major intracellular Ca(2+)-storage organelle, have an immediate effect on the physiological function of mitochondria and lysosomes. Also, the lysosomes can act as a Ca(2+) source for Ca(2+) release into the cytosol, thereby influencing ER-based Ca(2+) signaling. Given the important role for mitochondria and lysosomes in cell survival, cell death and cell adaptation processes, it has become increasingly clear that Ca(2+) signals from or towards these organelles impact these processes. In this review, we discuss the most recent insights in the emerging role of Ca(2+) signaling in cellular survival by controlling basal mitochondrial bioenergetics and by regulating apoptosis, a mitochondrial process, and autophagy, a lysosomal process, in response to cell damage and cell stress.
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Affiliation(s)
- Rita M L La Rovere
- KU Leuven, Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, BE-3000 Leuven, Belgium
| | - Gemma Roest
- KU Leuven, Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, BE-3000 Leuven, Belgium
| | - Geert Bultynck
- KU Leuven, Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, BE-3000 Leuven, Belgium.
| | - Jan B Parys
- KU Leuven, Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, BE-3000 Leuven, Belgium.
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411
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Burton GJ, Yung HW, Murray AJ. Mitochondrial - Endoplasmic reticulum interactions in the trophoblast: Stress and senescence. Placenta 2016; 52:146-155. [PMID: 27091649 DOI: 10.1016/j.placenta.2016.04.001] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 03/30/2016] [Accepted: 04/01/2016] [Indexed: 12/22/2022]
Abstract
Placental stress has been implicated in the pathophysiology of complications of pregnancy, including growth restriction and pre-eclampsia. Initially, attention focused on oxidative stress, but recently mitochondrial and endoplasmic reticulum stress have been identified. Complex molecular interactions exist among these different forms of stress, making it unlikely that any occurs in isolation. In part, this is due to close physiological connections between the two organelles principally involved, mitochondria and the endoplasmic reticulum (ER), mediated through Ca2+ signalling. Here, we review the involvement of the mitochondria-ER unit in the generation of stress within the trophoblast, and consider consequences for obstetric outcome. Mild stress may induce adaptive responses, including upregulation of antioxidant defences and autophagy, while moderate levels may affect stem cell behaviour and reduce cell proliferation, contributing to the growth-restricted phenotype. High levels of stress can stimulate release of pro-inflammatory cytokines and anti-angiogenic factors, increasing the risk of pre-eclampsia. In addition, chronic stress may promote senescence of the trophoblast, which in other cell types leads to a pro-inflammatory senescence-associated secretory phenotype. Evidence from rodents suggests that a degree of trophoblastic stress develops with increasing gestational age in normal pregnancies. The increase in maternal concentrations of soluble fms-like tyrosine kinase-1 (sFlt-1) and reduction in placental growth factor (PlGF) suggest the same may occur in the human, starting around 30 weeks of pregnancy. Placental malperfusion, or co-existing maternal conditions, such as diabetes, will exacerbate that stress. Amelioration of trophoblastic stress should remain a research priority, but will be difficult due to the complexity of the molecular pathways involved.
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Affiliation(s)
- G J Burton
- Centre for Trophoblast Research and Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK.
| | - H W Yung
- Centre for Trophoblast Research and Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK
| | - A J Murray
- Centre for Trophoblast Research and Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK
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Krols M, van Isterdael G, Asselbergh B, Kremer A, Lippens S, Timmerman V, Janssens S. Mitochondria-associated membranes as hubs for neurodegeneration. Acta Neuropathol 2016; 131:505-23. [PMID: 26744348 PMCID: PMC4789254 DOI: 10.1007/s00401-015-1528-7] [Citation(s) in RCA: 147] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 12/18/2015] [Accepted: 12/18/2015] [Indexed: 12/17/2022]
Abstract
There is a growing appreciation that membrane-bound organelles in eukaryotic cells communicate directly with one another through direct membrane contact sites. Mitochondria-associated membranes are specialized subdomains of the endoplasmic reticulum that function as membrane contact sites between the endoplasmic reticulum and mitochondria. These sites have emerged as major players in lipid metabolism and calcium signaling. More recently also autophagy and mitochondrial dynamics have been found to be regulated at ER-mitochondria contact sites. Neurons critically depend on mitochondria-associated membranes as a means to exchange metabolites and signaling molecules between these organelles. This is underscored by the fact that genes affecting mitochondrial and endoplasmic reticulum homeostasis are clearly overrepresented in several hereditary neurodegenerative disorders. Conversely, the processes affected by the contact sites between the endoplasmic reticulum and mitochondria are widely implicated in neurodegeneration. This review will focus on the most recent data addressing the structural composition and function of the mitochondria-associated membranes. In addition, the 3D morphology of the contact sites as observed using volume electron microscopy is discussed. Finally, it will highlight the role of several key proteins associated with these contact sites that are involved not only in dementias, amyotrophic lateral sclerosis and Parkinson's disease, but also in axonopathies such as hereditary spastic paraplegia and Charcot-Marie-Tooth disease.
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413
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Su L, Zhang Y, He K, Wei S, Pei H, Wang Q, Yang D, Yang Y. Activation of transient receptor potential vanilloid 1 accelerates re-endothelialization and inhibits neointimal formation after vascular injury. J Vasc Surg 2016; 65:197-205.e2. [PMID: 26947234 DOI: 10.1016/j.jvs.2015.12.037] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 12/10/2015] [Indexed: 02/06/2023]
Abstract
OBJECTIVE Transient receptor potential vanilloid 1 (TRPV1) is an important regulator of endothelial function, but the effects of TRPV1 on endothelial recovery and neointimal formation after vascular injury remain elusive. We tested the effects of activating TRPV1 using capsaicin on re-endothelialization and neointimal formation after wire-induced injury of the carotid artery in mice. METHODS The human umbilical vein endothelial cells (HUVECs) were treated with the TRPV1 agonist capsaicin, its antagonist capsazepine, intracellular calcium chelator BAPTA, or mitofusin 2 (Mfn2)-specific short interfering RNA (siRNA). The migration, proliferation, mitochondrial morphology, membrane potential, and adenosine triphosphate production were measured. The carotid artery wire injury procedure was performed in male TRPV1 knockout mice and C57BL/6J wild-type (WT) mice that were then treated with or without Mfn2 siRNA. The re-endothelialization and neointimal formation were evaluated. RESULTS Capsaicin significantly enhanced the migration and proliferation of HUVECs. Both capsazepine and BAPTA abolished capsaicin-induced migration and proliferation of HUVECs. In addition, capsaicin stimulated the formation of reticular mitochondria, augmented mitochondrial membrane potential, increased adenosine triphosphate production, and upregulated Mfn2. However, these effects were attenuated by knockdown of Mfn2 with specific siRNA. Dietary capsaicin markedly accelerated re-endothelialization and inhibited neointimal formation in WT mice but not in TRPV1 knockout mice. Moreover, Mfn2 siRNA also attenuated capsaicin-induced enhancement of endothelial recovery and suppression of neointimal hyperplasia in WT mice. CONCLUSIONS Activation of TRPV1 with capsaicin attenuates neointimal formation by accelerating re-endothelialization through upregulation of Mfn2.
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Affiliation(s)
- Linan Su
- Department of Cardiology, Chengdu Military General Hospital, Chengdu, Sichuan, China
| | - Yunrong Zhang
- Department of Cardiology, Chengdu Military General Hospital, Chengdu, Sichuan, China
| | - Kecheng He
- Department of Cardiology, Chengdu Military General Hospital, Chengdu, Sichuan, China
| | - Shujie Wei
- Department of Cardiology, Chengdu Military General Hospital, Chengdu, Sichuan, China
| | - Haifeng Pei
- Department of Cardiology, Chengdu Military General Hospital, Chengdu, Sichuan, China
| | - Qiang Wang
- Department of Cardiology, Chengdu Military General Hospital, Chengdu, Sichuan, China
| | - Dachun Yang
- Department of Cardiology, Chengdu Military General Hospital, Chengdu, Sichuan, China.
| | - Yongjian Yang
- Department of Cardiology, Chengdu Military General Hospital, Chengdu, Sichuan, China
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414
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There's Something Wrong with my MAM; the ER-Mitochondria Axis and Neurodegenerative Diseases. Trends Neurosci 2016; 39:146-157. [PMID: 26899735 PMCID: PMC4780428 DOI: 10.1016/j.tins.2016.01.008] [Citation(s) in RCA: 329] [Impact Index Per Article: 41.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 01/19/2016] [Accepted: 01/21/2016] [Indexed: 12/18/2022]
Abstract
Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis with associated frontotemporal dementia (ALS/FTD) are major neurodegenerative diseases for which there are no cures. All are characterised by damage to several seemingly disparate cellular processes. The broad nature of this damage makes understanding pathogenic mechanisms and devising new treatments difficult. Can the different damaged functions be linked together in a common disease pathway and which damaged function should be targeted for therapy? Many functions damaged in neurodegenerative diseases are regulated by communications that mitochondria make with a specialised region of the endoplasmic reticulum (ER; mitochondria-associated ER membranes or 'MAM'). Moreover, several recent studies have shown that disturbances to ER-mitochondria contacts occur in neurodegenerative diseases. Here, we review these findings.
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415
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Qi H, Shuai J. Alzheimer's disease via enhanced calcium signaling caused by the decrease of endoplasmic reticulum-mitochondrial distance. Med Hypotheses 2016; 89:28-31. [PMID: 26968904 DOI: 10.1016/j.mehy.2016.01.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 01/30/2016] [Indexed: 10/22/2022]
Abstract
It has long been recognized that Ca(2+) dysregulation is relevant to the initiation of Alzheimer's disease (AD), and most recent works have suggested that increased cross-talk between endoplasmic reticulum (ER) and mitochondria plays an important role in the pathogenesis of the disease. However, the detailed mechanism involved has not been fully elucidated. Owing to its importance in the regulation of Ca(2+) signaling, ER-mitochondrial distance in the neurons is tightly controlled in the physiological conditions. When the distance is decreased, Ca(2+) overload occurs both in the cytosol and mitochondria. The cytosolic Ca(2+) overload can (1) hyperactivate Ca(2+)-dependent enzymes, which in turn regulate activities of pro-apoptotic BCL-2 family proteins, causing mitochondrial outer membrane permeabilization and thereby resulting in the release of cytochrome c to activate caspase-3; (2) indirectly activate caspase-3 through the activation of caspase-12; and (3) promote the production and aggregation of β-amyloid. The three pathways eventually trigger neuronal apoptotic cell death. The mitochondrial Ca(2+) overload can lead to increased generation of reactive oxygen species, inducing the opening of the mitochondrial permeability transition pore and ultimately causing neuronal apoptotic and necrotic cell death. The resultant death of neurons which are responsible for memory and cognition would contribute to the pathogenesis of AD. Therefore, we propose that the reduction in the distance between ER and mitochondria may be implicated in AD pathology by enhanced Ca(2+) signaling, which provides a more complete picture of the Ca(2+) hypothesis of AD.
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Affiliation(s)
- Hong Qi
- Complex Systems Research Center, Shanxi University, Taiyuan 030006, PR China.
| | - Jianwei Shuai
- Department of Physics, Xiamen University, Xiamen 361005, PR China; State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, Xiamen University, Xiamen 361005, PR China.
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416
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Lipid transfer and metabolism across the endolysosomal-mitochondrial boundary. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:880-894. [PMID: 26852832 DOI: 10.1016/j.bbalip.2016.02.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Revised: 01/30/2016] [Accepted: 02/03/2016] [Indexed: 01/10/2023]
Abstract
Lysosomes and mitochondria occupy a central stage in the maintenance of cellular homeostasis, by playing complementary roles in nutrient sensing and energy metabolism. Specifically, these organelles function as signaling hubs that integrate environmental and endogenous stimuli with specific metabolic responses. In particular, they control various lipid biosynthetic and degradative pipelines, either directly or indirectly, by regulating major cellular metabolic pathways, and by physical and functional connections established with each other and with other organelles. Membrane contact sites allow the exchange of ions and molecules between organelles, even without membrane fusion, and are privileged routes for lipid transfer among different membrane compartments. These inter-organellar connections typically involve the endoplasmic reticulum. Direct membrane contacts have now been described also between lysosomes, autophagosomes, lipid droplets, and mitochondria. This review focuses on these recently identified membrane contact sites, and on their role in lipid biosynthesis, exchange, turnover and catabolism. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon.
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417
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Mukherjee R, Chakrabarti O. Ubiquitin mediated regulation of the E3 ligase GP78 by Mahogunin in trans affects mitochondrial homeostasis. J Cell Sci 2016; 129:757-73. [DOI: 10.1242/jcs.176537] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 12/29/2015] [Indexed: 12/29/2022] Open
Abstract
Cellular quality control provides an efficient surveillance system to regulate mitochondrial turn-over. This study elucidates a novel interaction of the cytosolic E3 ligase, MGRN1 with the ER ubiquitin E3 ligase, GP78. Loss of Mgrn1 function has been implicated in late-onset spongiform neurodegeneration, congenital heart defects amongst several developmental defects. MGRN1 ubiquitinates GP78 in trans via non-canonical K11 linkages. This helps maintain constitutively low levels of GP78 in healthy cells, in turn downregulating mitophagy. GP78, however, does not regulate MGRN1. When mitochondria are stressed, cytosolic Ca2+ increases.This leads to reduced interaction between MGRN1 and GP78 and its compromised ubiquitination. Chelating Ca2+ restores association between the two ligases and the trans ubiquitination. Catalytic inactivation of MGRN1 results in elevated levels of GP78 and consequential increase in the initiation of mitophagy. This is significant because functional depletion of MGRN1 by membrane-associated disease causing prion protein, CtmPrP affects polyubiquitination and degradation of GP78, also leading to an increase in mitophagy events. This suggests that MGRN1 participates in mitochondrial quality control and could contribute to neurodegeneration in a sub-set of CtmPrP mediated prion diseases.
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Affiliation(s)
- Rukmini Mukherjee
- Biophysics & Structural Genomics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata – 700064, India
| | - Oishee Chakrabarti
- Biophysics & Structural Genomics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata – 700064, India
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418
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Prudent J, Zunino R, Sugiura A, Mattie S, Shore GC, McBride HM. MAPL SUMOylation of Drp1 Stabilizes an ER/Mitochondrial Platform Required for Cell Death. Mol Cell 2015; 59:941-55. [PMID: 26384664 DOI: 10.1016/j.molcel.2015.08.001] [Citation(s) in RCA: 234] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 06/11/2015] [Accepted: 08/04/2015] [Indexed: 01/01/2023]
Abstract
There has been evidence that mitochondrial fragmentation is required for apoptosis, but the molecular links between the machinery regulating dynamics and cell death have been controversial. Indeed, activated BAX and BAK can form functional channels in liposomes, bringing into question the contribution of mitochondrial dynamics in apoptosis. We now demonstrate that the activation of apoptosis triggers MAPL/MUL1-dependent SUMOylation of the fission GTPase Drp1, a process requisite for cytochrome c release. SUMOylated Drp1 functionally stabilizes ER/mitochondrial contact sites that act as hotspots for mitochondrial constriction, calcium flux, cristae remodeling, and cytochrome c release. The loss of MAPL does not alter the activation and assembly of BAX/BAK oligomers, indicating that MAPL is activated downstream of BAX/BAK. This work demonstrates how interorganellar contacts are dynamically regulated through active SUMOylation during apoptosis, creating a stabilized platform that signals cytochrome c release.
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Affiliation(s)
- Julien Prudent
- Montreal Neurological Institute, McGill University, 3801 University Ave, Montreal, QC H3A 2B4, Canada
| | - Rodolfo Zunino
- Montreal Neurological Institute, McGill University, 3801 University Ave, Montreal, QC H3A 2B4, Canada
| | - Ayumu Sugiura
- Montreal Neurological Institute, McGill University, 3801 University Ave, Montreal, QC H3A 2B4, Canada
| | - Sevan Mattie
- Montreal Neurological Institute, McGill University, 3801 University Ave, Montreal, QC H3A 2B4, Canada
| | - Gordon C Shore
- McIntyre Medical Sciences Building, Department of Biochemistry, McGill University, Montreal, QC H3G 1Y6, Canada
| | - Heidi M McBride
- Montreal Neurological Institute, McGill University, 3801 University Ave, Montreal, QC H3A 2B4, Canada.
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419
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Phillips MJ, Voeltz GK. Structure and function of ER membrane contact sites with other organelles. Nat Rev Mol Cell Biol 2015; 17:69-82. [PMID: 26627931 DOI: 10.1038/nrm.2015.8] [Citation(s) in RCA: 638] [Impact Index Per Article: 70.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The endoplasmic reticulum (ER) is the largest organelle in the cell, and its functions have been studied for decades. The past several years have provided novel insights into the existence of distinct domains between the ER and other organelles, known as membrane contact sites (MCSs). At these contact sites, organelle membranes are closely apposed and tethered, but do not fuse. Here, various protein complexes can work in concert to perform specialized functions such as binding, sensing and transferring molecules, as well as engaging in organelle biogenesis and dynamics. This Review describes the structure and functions of MCSs, primarily focusing on contacts of the ER with mitochondria and endosomes.
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Affiliation(s)
- Melissa J Phillips
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309, USA
| | - Gia K Voeltz
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309, USA
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420
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Von Stockum S, Nardin A, Schrepfer E, Ziviani E. Mitochondrial dynamics and mitophagy in Parkinson's disease: A fly point of view. Neurobiol Dis 2015; 90:58-67. [PMID: 26550693 DOI: 10.1016/j.nbd.2015.11.002] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 11/02/2015] [Accepted: 11/05/2015] [Indexed: 12/27/2022] Open
Abstract
Mitochondria are double membrane-bounded organelles residing in the cytoplasm of almost all eukaryotic cells, which convert energy from the disposal of organic substrates into an electrochemical gradient that is in turn converted into ATP. However, the ion gradient that is generated through the oxidation of nutrients, may lead to the production of reactive oxygen species (ROS), which can generate free radicals, damaging cells and contributing to disease. Originally described as static structures, to date they are considered extremely plastic and dynamic organelles. In this respect, mitochondrial dynamics is crucial to prevent potential damage that is generated by ROS. For instance, mitochondria elongate to dilute oxidized proteins into the mitochondrial network, and they fragment to allow selective elimination of dysfunctional mitochondria via mitophagy. Accordingly, mitochondrial dynamics perturbation may compromise the selective elimination of damaged proteins and dysfunctional organelles and lead to the development of different diseases including neurodegenerative diseases. In recent years the fruit fly Drosophila melanogaster has proved to be a valuable model system to evaluate the consequences of mitochondria quality control dysfunction in vivo, particularly with respect to PINK1/Parkin dependent dysregulation of mitophagy in the onset of Parkinson's Disease (PD). The current challenge is to be able to use fly based genetic strategies to gain further insights into molecular mechanisms underlying disease in order to develop new therapeutic strategies. This article is part of a Special Issue entitled: Role of mitochondria in physiological and pathophysiological functions in the central nervous system.
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Affiliation(s)
| | - Alice Nardin
- Department of Biochemistry, University of Padova, via Ugo Bassi 56, Padova, Italy
| | - Emilie Schrepfer
- Department of Biochemistry, University of Padova, via Ugo Bassi 56, Padova, Italy; VIMM, Venetian Institute of Molecular Medicine, Via Giuseppe Orus 2, Padova, Italy
| | - Elena Ziviani
- Fondazione Ospedale San Camillo, IRCCS, Lido di Venezia, Venezia, Italy; Department of Biochemistry, University of Padova, via Ugo Bassi 56, Padova, Italy.
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421
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Diaz B, Fuentes-Mera L, Tovar A, Montiel T, Massieu L, Martínez-Rodríguez H, Camacho A. Saturated lipids decrease mitofusin 2 leading to endoplasmic reticulum stress activation and insulin resistance in hypothalamic cells. Brain Res 2015; 1627:80-9. [DOI: 10.1016/j.brainres.2015.09.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 07/23/2015] [Accepted: 09/10/2015] [Indexed: 02/07/2023]
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422
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Bertholet AM, Delerue T, Millet AM, Moulis MF, David C, Daloyau M, Arnauné-Pelloquin L, Davezac N, Mils V, Miquel MC, Rojo M, Belenguer P. Mitochondrial fusion/fission dynamics in neurodegeneration and neuronal plasticity. Neurobiol Dis 2015; 90:3-19. [PMID: 26494254 DOI: 10.1016/j.nbd.2015.10.011] [Citation(s) in RCA: 245] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 09/16/2015] [Accepted: 10/13/2015] [Indexed: 12/17/2022] Open
Abstract
Mitochondria are dynamic organelles that continually move, fuse and divide. The dynamic balance of fusion and fission of mitochondria determines their morphology and allows their immediate adaptation to energetic needs, keeps mitochondria in good health by restoring or removing damaged organelles or precipitates cells in apoptosis in cases of severe defects. Mitochondrial fusion and fission are essential in mammals and their disturbances are associated with several diseases. However, while mitochondrial fusion/fission dynamics, and the proteins that control these processes, are ubiquitous, associated diseases are primarily neurological disorders. Accordingly, inactivation of the main actors of mitochondrial fusion/fission dynamics is associated with defects in neuronal development, plasticity and functioning, both ex vivo and in vivo. Here, we present the central actors of mitochondrial fusion and fission and review the role of mitochondrial dynamics in neuronal physiology and pathophysiology. Particular emphasis is placed on the three main actors of these processes i.e. DRP1,MFN1-2, and OPA1 as well as on GDAP1, a protein of the mitochondrial outer membrane preferentially expressed in neurons. This article is part of a Special Issue entitled: Mitochondria & Brain.
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Affiliation(s)
- A M Bertholet
- Université de Toulouse, Centre de Biologie du Développement, CNRS, UMR5547/Université Paul Sabatier, Toulouse, France; CNRS, Centre de Biologie du Développement, UMR5547/Université Paul Sabatier, Toulouse, France
| | - T Delerue
- Université de Toulouse, Centre de Biologie du Développement, CNRS, UMR5547/Université Paul Sabatier, Toulouse, France; CNRS, Centre de Biologie du Développement, UMR5547/Université Paul Sabatier, Toulouse, France
| | - A M Millet
- Université de Toulouse, Centre de Biologie du Développement, CNRS, UMR5547/Université Paul Sabatier, Toulouse, France; CNRS, Centre de Biologie du Développement, UMR5547/Université Paul Sabatier, Toulouse, France
| | - M F Moulis
- Université de Toulouse, Centre de Biologie du Développement, CNRS, UMR5547/Université Paul Sabatier, Toulouse, France; CNRS, Centre de Biologie du Développement, UMR5547/Université Paul Sabatier, Toulouse, France
| | - C David
- CNRS, Institut de Biochimie et Génétique Cellulaires (IBGC), UMR5095, Bordeaux, France; Université de Bordeaux, Institut de Biochimie et Génétique Cellulaires (IBGC), UMR5095, Bordeaux, France
| | - M Daloyau
- Université de Toulouse, Centre de Biologie du Développement, CNRS, UMR5547/Université Paul Sabatier, Toulouse, France; CNRS, Centre de Biologie du Développement, UMR5547/Université Paul Sabatier, Toulouse, France
| | - L Arnauné-Pelloquin
- Université de Toulouse, Centre de Biologie du Développement, CNRS, UMR5547/Université Paul Sabatier, Toulouse, France; CNRS, Centre de Biologie du Développement, UMR5547/Université Paul Sabatier, Toulouse, France
| | - N Davezac
- Université de Toulouse, Centre de Biologie du Développement, CNRS, UMR5547/Université Paul Sabatier, Toulouse, France; CNRS, Centre de Biologie du Développement, UMR5547/Université Paul Sabatier, Toulouse, France
| | - V Mils
- Université de Toulouse, Centre de Biologie du Développement, CNRS, UMR5547/Université Paul Sabatier, Toulouse, France; CNRS, Centre de Biologie du Développement, UMR5547/Université Paul Sabatier, Toulouse, France
| | - M C Miquel
- Université de Toulouse, Centre de Biologie du Développement, CNRS, UMR5547/Université Paul Sabatier, Toulouse, France; CNRS, Centre de Biologie du Développement, UMR5547/Université Paul Sabatier, Toulouse, France
| | - M Rojo
- CNRS, Institut de Biochimie et Génétique Cellulaires (IBGC), UMR5095, Bordeaux, France; Université de Bordeaux, Institut de Biochimie et Génétique Cellulaires (IBGC), UMR5095, Bordeaux, France.
| | - P Belenguer
- Université de Toulouse, Centre de Biologie du Développement, CNRS, UMR5547/Université Paul Sabatier, Toulouse, France; CNRS, Centre de Biologie du Développement, UMR5547/Université Paul Sabatier, Toulouse, France.
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423
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Schrader M, Godinho LF, Costello JL, Islinger M. The different facets of organelle interplay-an overview of organelle interactions. Front Cell Dev Biol 2015; 3:56. [PMID: 26442263 PMCID: PMC4585249 DOI: 10.3389/fcell.2015.00056] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 09/08/2015] [Indexed: 12/28/2022] Open
Abstract
Membrane-bound organelles such as mitochondria, peroxisomes, or the endoplasmic reticulum (ER) create distinct environments to promote specific cellular tasks such as ATP production, lipid breakdown, or protein export. During recent years, it has become evident that organelles are integrated into cellular networks regulating metabolism, intracellular signaling, cellular maintenance, cell fate decision, and pathogen defence. In order to facilitate such signaling events, specialized membrane regions between apposing organelles bear distinct sets of proteins to enable tethering and exchange of metabolites and signaling molecules. Such membrane associations between the mitochondria and a specialized site of the ER, the mitochondria associated-membrane (MAM), as well as between the ER and the plasma membrane (PAM) have been partially characterized at the molecular level. However, historical and recent observations imply that other organelles like peroxisomes, lysosomes, and lipid droplets might also be involved in the formation of such apposing membrane contact sites. Alternatively, reports on so-called mitochondria derived-vesicles (MDV) suggest alternative mechanisms of organelle interaction. Moreover, maintenance of cellular homeostasis requires the precise removal of aged organelles by autophagy—a process which involves the detection of ubiquitinated organelle proteins by the autophagosome membrane, representing another site of membrane associated-signaling. This review will summarize the available data on the existence and composition of organelle contact sites and the molecular specializations each site uses in order to provide a timely overview on the potential functions of organelle interaction.
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Affiliation(s)
- Michael Schrader
- Department of Biosciences, College of Life and Environmental Sciences, University of Exeter Exeter, UK
| | - Luis F Godinho
- Centre for Cell Biology and Department of Biology, University of Aveiro Aveiro, Portugal
| | - Joseph L Costello
- Department of Biosciences, College of Life and Environmental Sciences, University of Exeter Exeter, UK
| | - Markus Islinger
- Neuroanatomy, Center for Biomedicine and Medical Technology Mannheim, University of Heidelberg Mannheim, Germany
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424
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Abstract
A number of chronic metabolic pathologies, including obesity, diabetes, cardiovascular disease, asthma, and cancer, cluster together to present the greatest threat to human health. As research in this field has advanced, it has become clear that unresolved metabolic inflammation, organelle dysfunction, and other cellular and metabolic stresses underlie the development of these chronic metabolic diseases. However, the relationship between these systems and pathological mechanisms is poorly understood. Here we discuss the role of cellular Ca(2+) homeostasis as a critical mechanism integrating the myriad of cellular and subcellular dysfunctional networks found in metabolic tissues such as liver and adipose tissue in the context of metabolic disease, particularly in obesity and diabetes.
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425
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UCP2 modulates single-channel properties of a MCU-dependent Ca(2+) inward current in mitochondria. Pflugers Arch 2015; 467:2509-18. [PMID: 26275882 PMCID: PMC4646917 DOI: 10.1007/s00424-015-1727-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 07/28/2015] [Accepted: 07/30/2015] [Indexed: 01/14/2023]
Abstract
The mitochondrial Ca(2+) uniporter is a highly Ca(2+)-selective protein complex that consists of the pore-forming mitochondrial Ca(2+) uniporter protein (MCU), the scaffolding essential MCU regulator (EMRE), and mitochondrial calcium uptake 1 and 2 (MICU1/2), which negatively regulate mitochondrial Ca(2+) uptake. We have previously reported that uncoupling proteins 2 and 3 (UCP2/3) are also engaged in the activity of mitochondrial Ca(2+) uptake under certain conditions, while the mechanism by which UCP2/3 facilitates mitochondrial Ca(2+) uniport remains elusive. This work was designed to investigate the impact of UCP2 on the three distinct mitochondrial Ca(2+) currents found in mitoplasts isolated from HeLa cells, the intermediate- (i-), burst- (b-) and extra-large (xl-) mitochondrial/mitoplast Ca(2+) currents (MCC). Using the patch clamp technique on mitoplasts from cells with reduced MCU and EMRE unveiled a very high affinity of MCU for xl-MCC that succeeds that for i-MCC, indicating the coexistence of at least two MCU/EMRE-dependent Ca(2+) currents. The manipulation of the expression level of UCP2 by either siRNA-mediated knockdown or overexpression changed exclusively the open probability (NPo) of xl-MCC by approx. 38% decrease or nearly a 3-fold increase, respectively. These findings confirm a regulatory role of UCP2 in mitochondrial Ca(2+) uptake and identify UCP2 as a selective modulator of just one distinct MCU/EMRE-dependent mitochondrial Ca(2+) inward current.
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426
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Kawalec M, Boratyńska-Jasińska A, Beręsewicz M, Dymkowska D, Zabłocki K, Zabłocka B. Mitofusin 2 Deficiency Affects Energy Metabolism and Mitochondrial Biogenesis in MEF Cells. PLoS One 2015; 10:e0134162. [PMID: 26230519 PMCID: PMC4521854 DOI: 10.1371/journal.pone.0134162] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2015] [Accepted: 07/06/2015] [Indexed: 12/13/2022] Open
Abstract
Mitofusin 2 (Mfn2), mitochondrial outer membrane protein which is involved in rearrangement of these organelles, was first described in pathology of hypertension and diabetes, and more recently much attention is paid to its functions in Charcot-Marie-Tooth type 2A neuropathy (CMT2A). Here, cellular energy metabolism was investigated in mouse embryonic fibroblasts (MEF) differing in the presence of the Mfn2 gene; control (MEFwt) and with Mfn2 gene depleted MEFMfn2-/-. These two cell lines were compared in terms of various parameters characterizing mitochondrial bioenergetics. Here, we have shown that relative rate of proliferation of MEFMfn2-/- cells versus control fibroblasts depend on serum supplementation of the growth media. Moreover, MEFMfn2-/- cells exhibited significantly increased respiration rate in comparison to MEFwt, regardless of serum supplementation of the medium. This effect was correlated with increased level of mitochondrial markers (TOM20 and NAO) as well as mitochondrial transcription factor A (TFAM) and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) protein levels and unchanged total ATP content. Interestingly, mitochondrial DNA content in MEFMfn2-/- cells was not reduced. Fundamentally, these results are in contrast to a commonly accepted belief that mitofusin 2 deficiency inevitably results in debilitation of mitochondrial energy metabolism. However, we suggest a balance between negative metabolic consequences of mitofusin 2 deficiency and adaptive processes exemplified by increased level of PGC-1α and TFAM transcription factor which prevent an excessive depletion of mtDNA and severe impairment of cell metabolism.
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Affiliation(s)
- Maria Kawalec
- Molecular Biology Unit, Mossakowski Medical Research Centre, PAS, Warsaw, Poland
| | | | | | - Dorota Dymkowska
- Department of Biochemistry, Nencki Institute of Experimental Biology, PAS, Warsaw, Poland
| | - Krzysztof Zabłocki
- Department of Biochemistry, Nencki Institute of Experimental Biology, PAS, Warsaw, Poland
| | - Barbara Zabłocka
- Molecular Biology Unit, Mossakowski Medical Research Centre, PAS, Warsaw, Poland
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427
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Wang PTC, Garcin PO, Fu M, Masoudi M, St-Pierre P, Panté N, Nabi IR. Distinct mechanisms controlling rough and smooth endoplasmic reticulum contacts with mitochondria. J Cell Sci 2015; 128:2759-65. [PMID: 26065430 DOI: 10.1242/jcs.171132] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 06/08/2015] [Indexed: 01/17/2023] Open
Abstract
Gp78 (also known as AMFR), an endoplasmic-reticulum (ER)-associated protein degradation (ERAD) E3 ubiquitin ligase, localizes to mitochondria-associated ER and targets the mitofusin (Mfn1 and Mfn2) mitochondrial fusion proteins for degradation. Gp78 is also the cell surface receptor for autocrine motility factor (AMF), which prevents Gp78-dependent mitofusin degradation. Gp78 ubiquitin ligase activity promotes ER-mitochondria association and ER-mitochondria Ca(2+) coupling, processes that are reversed by AMF. Electron microscopy of HT-1080 fibrosarcoma cancer cells identified both smooth ER (SER; ∼8 nm) and wider (∼50-60 nm) rough ER (RER)-mitochondria contacts. Both short hairpin RNA (shRNA)-mediated knockdown of Gp78 (shGp78) and AMF treatment selectively reduced the extent of RER-mitochondria contacts without impacting on SER--mitochondria contacts. Concomitant small interfering RNA (siRNA)-mediated knockdown of Mfn1 increased SER-mitochondria contacts in both control and shGp78 cells, whereas knockdown of Mfn2 increased RER-mitochondria contacts selectively in shGp78 HT-1080 cells. The mitofusins therefore inhibit ER-mitochondria interaction. Regulation of close SER-mitochondria contacts by Mfn1 and of RER-mitochondria contacts by AMF-sensitive Gp78-mediated degradation of Mfn2 define new mechanisms that regulate ER-mitochondria interactions.
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Affiliation(s)
- Peter T C Wang
- Departments of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Pierre O Garcin
- Department of Zoology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Min Fu
- Departments of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Matthew Masoudi
- Departments of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Pascal St-Pierre
- Departments of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Nelly Panté
- Department of Zoology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Ivan R Nabi
- Departments of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
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