101
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Zou C, Synan MJ, Li J, Xiong S, Manni ML, Liu Y, Chen BB, Zhao Y, Shiva S, Tyurina YY, Jiang J, Lee JS, Das S, Ray A, Ray P, Kagan VE, Mallampalli RK. LPS impairs oxygen utilization in epithelia by triggering degradation of the mitochondrial enzyme Alcat1. J Cell Sci 2015; 129:51-64. [PMID: 26604221 DOI: 10.1242/jcs.176701] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 11/09/2015] [Indexed: 12/18/2022] Open
Abstract
Cardiolipin (also known as PDL6) is an indispensable lipid required for mitochondrial respiration that is generated through de novo synthesis and remodeling. Here, the cardiolipin remodeling enzyme, acyl-CoA:lysocardiolipin-acyltransferase-1 (Alcat1; SwissProt ID, Q6UWP7) is destabilized in epithelia by lipopolysaccharide (LPS) impairing mitochondrial function. Exposure to LPS selectively decreased levels of carbon 20 (C20)-containing cardiolipin molecular species, whereas the content of C18 or C16 species was not significantly altered, consistent with decreased levels of Alcat1. Alcat1 is a labile protein that is lysosomally degraded by the ubiquitin E3 ligase Skp-Cullin-F-box containing the Fbxo28 subunit (SCF-Fbxo28) that targets Alcat1 for monoubiquitylation at residue K183. Interestingly, K183 is also an acetylation-acceptor site, and acetylation conferred stability to the enzyme. Histone deacetylase 2 (HDAC2) interacted with Alcat1, and expression of a plasmid encoding HDAC2 or treatment of cells with LPS deacetylated and destabilized Alcat1, whereas treatment of cells with a pan-HDAC inhibitor increased Alcat1 levels. Alcat1 degradation was partially abrogated in LPS-treated cells that had been silenced for HDAC2 or treated with MLN4924, an inhibitor of Cullin-RING E3 ubiquitin ligases. Thus, LPS increases HDAC2-mediated Alcat1 deacetylation and facilitates SCF-Fbxo28-mediated disposal of Alcat1, thus impairing mitochondrial integrity.
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Affiliation(s)
- Chunbin Zou
- Department of Medicine, Acute Lung Injury Center of Excellence, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Matthew J Synan
- Department of Medicine, Acute Lung Injury Center of Excellence, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Jin Li
- Department of Medicine, Acute Lung Injury Center of Excellence, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Sheng Xiong
- Institute of Biomedicine & National Engineering Research Center of Genetic Medicine, College of Life Science and Technology, Jinan University, Guangzhou 510630, China
| | - Michelle L Manni
- Department of Medicine, Acute Lung Injury Center of Excellence, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Yuan Liu
- Department of Medicine, Acute Lung Injury Center of Excellence, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Bill B Chen
- Department of Medicine, Acute Lung Injury Center of Excellence, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Yutong Zhao
- Department of Medicine, Acute Lung Injury Center of Excellence, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Sruti Shiva
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Yulia Y Tyurina
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Jianfei Jiang
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Janet S Lee
- Department of Medicine, Acute Lung Injury Center of Excellence, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Sudipta Das
- Department of Medicine, Acute Lung Injury Center of Excellence, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Anuradha Ray
- Department of Medicine, Acute Lung Injury Center of Excellence, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Prabir Ray
- Department of Medicine, Acute Lung Injury Center of Excellence, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Valerian E Kagan
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15213, USA Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Rama K Mallampalli
- Department of Medicine, Acute Lung Injury Center of Excellence, University of Pittsburgh, Pittsburgh, PA 15213, USA Department of Cell Biology and Physiology and Bioengineering, University of Pittsburgh, Pittsburgh, PA 15213, USA Medical Specialty Service Line, Veterans Affairs Pittsburgh Healthcare System, Pittsburgh, PA 15240, USA
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102
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Moustapha A, Pérétout PA, Rainey NE, Sureau F, Geze M, Petit JM, Dewailly E, Slomianny C, Petit PX. Curcumin induces crosstalk between autophagy and apoptosis mediated by calcium release from the endoplasmic reticulum, lysosomal destabilization and mitochondrial events. Cell Death Discov 2015; 1:15017. [PMID: 27551451 PMCID: PMC4979459 DOI: 10.1038/cddiscovery.2015.17] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 06/23/2015] [Indexed: 12/22/2022] Open
Abstract
Curcumin, a major active component of turmeric (Curcuma longa, L.), has anticancer effects. In vitro studies suggest that curcumin inhibits cancer cell growth by activating apoptosis, but the mechanism underlying these effects is still unclear. Here, we investigated the mechanisms leading to apoptosis in curcumin-treated cells. Curcumin induced endoplasmic reticulum stress causing calcium release, with a destabilization of the mitochondrial compartment resulting in apoptosis. These events were also associated with lysosomal membrane permeabilization and of caspase-8 activation, mediated by cathepsins and calpains, leading to Bid cleavage. Truncated tBid disrupts mitochondrial homeostasis and enhance apoptosis. We followed the induction of autophagy, marked by the formation of autophagosomes, by staining with acridine orange in cells exposed curcumin. At this concentration, only the early events of apoptosis (initial mitochondrial destabilization with any other manifestations) were detectable. Western blotting demonstrated the conversion of LC3-I to LC3-II (light chain 3), a marker of active autophagosome formation. We also found that the production of reactive oxygen species and formation of autophagosomes following curcumin treatment was almost completely blocked by N-acetylcystein, the mitochondrial specific antioxidants MitoQ10 and SKQ1, the calcium chelators, EGTA-AM or BAPTA-AM, and the mitochondrial calcium uniporter inhibitor, ruthenium red. Curcumin-induced autophagy failed to rescue all cells and most cells underwent type II cell death following the initial autophagic processes. All together, these data imply a fail-secure mechanism regulated by autophagy in the action of curcumin, suggesting a therapeutic potential for curcumin. Offering a novel and effective strategy for the treatment of malignant cells.
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Affiliation(s)
- A Moustapha
- INSERM U1124 'Toxicologie, Pharmacologie et Signalisation Cellulaire', Université Paris-Descartes, Centre Universitaire des Saints-Pères , Paris, France
| | - P A Pérétout
- INSERM U1124 'Toxicologie, Pharmacologie et Signalisation Cellulaire', Université Paris-Descartes, Centre Universitaire des Saints-Pères , Paris, France
| | - N E Rainey
- INSERM U1124 'Toxicologie, Pharmacologie et Signalisation Cellulaire', Université Paris-Descartes, Centre Universitaire des Saints-Pères , Paris, France
| | - F Sureau
- Université Pierre et Marie Curie-Paris 6, Laboratoire Jean Perrin , Paris, France
| | - M Geze
- Muséum National d'Histoire Naturelles, CeMIM/USM 0504, 'Biologie Fonctionnelles des Protozoaires' 57 , Paris, France
| | - J-M Petit
- Muséum National d'Histoire Naturelles, UMR 7245 CNRS/MNHN 'Molécules de Communication et Adaptation des Micro-organismes' 57 , Paris, France
| | - E Dewailly
- Laboratoire de Physiologie cellulaire, INSERM U800, Université des Sciences et Techniques de Lille 1 , Villeneuve d'Ascq, France
| | - C Slomianny
- Laboratoire de Physiologie cellulaire, INSERM U800, Université des Sciences et Techniques de Lille 1 , Villeneuve d'Ascq, France
| | - P X Petit
- INSERM U1124 'Toxicologie, Pharmacologie et Signalisation Cellulaire', Université Paris-Descartes, Centre Universitaire des Saints-Pères , Paris, France
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103
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Bernardi P, Rasola A, Forte M, Lippe G. The Mitochondrial Permeability Transition Pore: Channel Formation by F-ATP Synthase, Integration in Signal Transduction, and Role in Pathophysiology. Physiol Rev 2015; 95:1111-55. [PMID: 26269524 DOI: 10.1152/physrev.00001.2015] [Citation(s) in RCA: 420] [Impact Index Per Article: 46.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The mitochondrial permeability transition (PT) is a permeability increase of the inner mitochondrial membrane mediated by a channel, the permeability transition pore (PTP). After a brief historical introduction, we cover the key regulatory features of the PTP and provide a critical assessment of putative protein components that have been tested by genetic analysis. The discovery that under conditions of oxidative stress the F-ATP synthases of mammals, yeast, and Drosophila can be turned into Ca(2+)-dependent channels, whose electrophysiological properties match those of the corresponding PTPs, opens new perspectives to the field. We discuss structural and functional features of F-ATP synthases that may provide clues to its transition from an energy-conserving into an energy-dissipating device as well as recent advances on signal transduction to the PTP and on its role in cellular pathophysiology.
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Affiliation(s)
- Paolo Bernardi
- Department of Biomedical Sciences and Consiglio Nazionale delle Ricerche Neuroscience Institute, University of Padova, Padova, Italy; Vollum Institute, Oregon Health and Sciences University, Portland, Oregon; and Department of Food Science, University of Udine, Udine, Italy
| | - Andrea Rasola
- Department of Biomedical Sciences and Consiglio Nazionale delle Ricerche Neuroscience Institute, University of Padova, Padova, Italy; Vollum Institute, Oregon Health and Sciences University, Portland, Oregon; and Department of Food Science, University of Udine, Udine, Italy
| | - Michael Forte
- Department of Biomedical Sciences and Consiglio Nazionale delle Ricerche Neuroscience Institute, University of Padova, Padova, Italy; Vollum Institute, Oregon Health and Sciences University, Portland, Oregon; and Department of Food Science, University of Udine, Udine, Italy
| | - Giovanna Lippe
- Department of Biomedical Sciences and Consiglio Nazionale delle Ricerche Neuroscience Institute, University of Padova, Padova, Italy; Vollum Institute, Oregon Health and Sciences University, Portland, Oregon; and Department of Food Science, University of Udine, Udine, Italy
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104
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Gaspard GJ, McMaster CR. Cardiolipin metabolism and its causal role in the etiology of the inherited cardiomyopathy Barth syndrome. Chem Phys Lipids 2015; 193:1-10. [PMID: 26415690 DOI: 10.1016/j.chemphyslip.2015.09.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 09/14/2015] [Accepted: 09/16/2015] [Indexed: 01/11/2023]
Abstract
Cardiolipin (CL) is a phospholipid with many unique characteristics. CL is synthesized in the mitochondria and resides almost exclusively within the mitochondrial inner membrane. Unlike most phospholipids that have two fatty acyl chains, CL possesses four fatty acyl chains resulting in unique biophysical characteristics that impact several biological processes including membrane fission and fusion. In addition, several proteins directly bind CL including proteins within the electron transport chain, the ADP/ATP carrier, and proteins that mediate mitophagy. Tafazzin is an enzyme that remodels saturated fatty acyl chains within CL to unsaturated fatty acyl chains, loss of function mutations in the TAZ gene encoding tafazzin are causal for the inherited cardiomyopathy Barth syndrome. Cells from Barth syndrome patients as well as several models of Barth have reduced mitochondrial functions including impaired electron transport chain function and increased reactive oxygen species (ROS) production. Mitochondria in cells from Barth syndrome patients, as well as several model organism mimics of Barth syndrome, are large and lack cristae consistent with the recently described role of CL participating in the generation of mitochondrial membrane contact sites. Cells with an inactive TAZ gene have also been shown to have a decreased capacity to undergo mitophagy when faced with stresses such as increased ROS or decreased mitochondrial quality control. This review describes CL metabolism and how defects in CL metabolism cause Barth syndrome, the etiology of Barth syndrome, and known modifiers of Barth syndrome phenotypes some of which could be explored for their amelioration of Barth syndrome in higher organisms.
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Affiliation(s)
- Gerard J Gaspard
- Departments of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, Canada
| | - Christopher R McMaster
- Departments of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, Canada; Departments of Pharmacology, Dalhousie University, Halifax, NS, Canada.
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105
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Luévano-Martínez LA, Kowaltowski AJ. Phosphatidylglycerol-derived phospholipids have a universal, domain-crossing role in stress responses. Arch Biochem Biophys 2015; 585:90-97. [PMID: 26391924 DOI: 10.1016/j.abb.2015.09.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 09/15/2015] [Accepted: 09/16/2015] [Indexed: 11/19/2022]
Abstract
Phosphatidylglycerol and phospholipids derived from it are widely distributed throughout the three domains of life. Cardiolipin is the best characterized of these phospholipids, and plays a key role in the response to environmental variations. Phosphatidylglycerol-derived phospholipids confer cell membranes with a wide range of responses, including changes in surface charge, fluidity, flexibility, morphology, biosynthesis and remodeling, that adapt the cell to these situations. Furthermore, the synthesis and remodeling of these phospholipids is finely regulated, highlighting the importance of these lipids in cell homeostasis and responses during stressful situations. In this article, we review the most important roles of these anionic phospholipids across domains, focusing on the biophysical basis by which these phospholipids are used in stress responses.
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Affiliation(s)
| | - Alicia J Kowaltowski
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, SP, Brazil.
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106
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Lack of mitochondrial topoisomerase I (TOP1mt) impairs liver regeneration. Proc Natl Acad Sci U S A 2015; 112:11282-7. [PMID: 26305952 DOI: 10.1073/pnas.1511016112] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The liver has an exceptional replicative capacity following partial hepatectomy or chemical injuries. Cellular proliferation requires increased production of energy and essential metabolites, which critically depend on the mitochondria. To determine whether Top1mt, the vertebrate mitochondrial topoisomerase, is involved in this process, we studied liver regeneration after carbon tetrachloride (CCl4) administration. TOP1mt knockout (KO) mice showed a marked reduction in regeneration and hepatocyte proliferation. The hepatic mitochondrial DNA (mtDNA) failed to increase during recovery from CCl4 exposure. Reduced glutathione was also depleted, indicating increased reactive oxygen species (ROS). Steady-state levels of ATP, O2 consumption, mtDNA, and mitochondrial mass were also reduced in primary hepatocytes from CCl4-treated KO mice. To further test whether Top1mt acted by enabling mtDNA regeneration, we tested TOP1mt KO fibroblasts and human colon carcinoma HCT116 cells and measured mtDNA after 3-d treatment with ethidium bromide. Both types of TOP1mt knockout cells showed defective mtDNA regeneration following mtDNA depletion. Our study demonstrates that Top1mt is required for normal mtDNA homeostasis and for linking mtDNA expansion with hepatocyte proliferation.
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107
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Differential reduction in cardiac and liver monolysocardiolipin acyltransferase-1 and reduction in cardiac and liver tetralinoleoyl-cardiolipin in the α-subunit of trifunctional protein heterozygous knockout mice. Biochem J 2015; 471:123-9. [PMID: 26251360 DOI: 10.1042/bj20150648] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 08/04/2015] [Indexed: 12/19/2022]
Abstract
The contribution of α-subunit of trifunctional protein (αTFP) to cardiolipin (CL) (diphosphatidylglycerol) remodelling and mitochondrial supercomplex formation was examined in heart and liver mitochondria from wild-type (WT) and αTFP heterozygous knockout [Mtpa(+/-)] mice. Mtpa(+/-) mouse heart and liver exhibited an approximate 55% and 50% reduction in αTFP protein expression compared with WT respectively. Monolysocardiolipin (MLCL) acyltransferase (MLCL AT)-1 protein derived from αTFP was reduced by 30% in Mtpa(+/-) mouse heart but not in liver compared with WT. In vitro acylation of MLCL was significantly reduced in heart but not in liver mitochondria of Mtpa(+/-) mice compared with WT. CL mass was reduced and significant reductions in linoleate-containing CL species, in particular tetralinoleoyl-CL (L4-CL) and trilinoleoyl-CL (L3-MLCL) species, were observed in heart and liver mitochondria of Mtpa(+/-) mice compared with WT. Cardiac and liver mitochondrial supercomplex assembly and NADH dehydrogenase (complex I) activity within these supercomplexes were unaltered in both Mtpa(+/-) mouse heart and Mtpa(+/-) mouse liver compared with WT. The results indicate that αTFP may modulate CL molecular species composition in murine heart and liver. In addition, L4-CL might not be an essential requirement for mitochondrial supercomplex assembly.
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108
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Reynolds S. Successful management of Barth syndrome: a systematic review highlighting the importance of a flexible and multidisciplinary approach. J Multidiscip Healthc 2015; 8:345-58. [PMID: 26251611 PMCID: PMC4524586 DOI: 10.2147/jmdh.s54802] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
This review describes and summarizes the available evidence related to the treatment and management of Barth syndrome. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standards were used to identify articles published between December 2004 and January 2015. The Cochrane Population, Intervention, Control, Outcome, Study Design (PICOS) approach was used to guide the article selection and evaluation process. Of the 128 articles screened, 28 articles matched the systematic review inclusion criteria. The results of this review indicate the need for a flexible and multidisciplinary approach to manage the symptoms most commonly associated with Barth syndrome. It is recommended that a comprehensive care team should include individuals with Barth syndrome, their family members and caregivers, as well as medical, rehabilitative, nutritional, psychological, and educational professionals. The evidence for specific treatments, therapies, and techniques for individuals with Barth syndrome is currently lacking in both quality and quantity.
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Affiliation(s)
- Stacey Reynolds
- Department of Occupational Therapy, Virginia Commonwealth University, Richmond, VA, USA
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109
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RCF1-dependent respiratory supercomplexes are integral for lifespan-maintenance in a fungal ageing model. Sci Rep 2015. [PMID: 26220011 PMCID: PMC4518240 DOI: 10.1038/srep12697] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Mitochondrial respiratory supercomplexes (mtRSCs) are stoichiometric assemblies of electron transport chain (ETC) complexes in the inner mitochondrial membrane. They are hypothesized to regulate electron flow, the generation of reactive oxygen species (ROS) and to stabilize ETC complexes. Using the fungal ageing model Podospora anserina, we investigated the impact of homologues of the Saccharomyces cerevisiae respiratory supercomplex factors 1 and 2 (termed PaRCF1 and PaRCF2) on mtRSC formation, fitness and lifespan. Whereas PaRCF2’s role seems negligible, ablation of PaRCF1 alters size of monomeric complex IV, reduces the abundance of complex IV-containing supercomplexes, negatively affects vital functions and shortens lifespan. PaRcf1 overexpression slightly prolongs lifespan, though without appreciably influencing ETC organization. Overall, our results identify PaRCF1 as necessary yet not sufficient for mtRSC formation and demonstrate that PaRCF1-dependent stability of complex IV and associated supercomplexes is highly relevant for maintenance of the healthy lifespan in a eukaryotic model organism.
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110
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Abstract
SIGNIFICANCE The molecular mechanism of aging is still vigorously debated, although a general consensus exists that mitochondria are significantly involved in this process. However, the previously postulated role of mitochondrial-derived reactive oxygen species (ROS) as the damaging agents inducing functional loss in aging has fallen out of favor in the recent past. In this review, we critically examine the role of ROS in aging in the light of recent advances on the relationship between mitochondrial structure and function. RECENT ADVANCES The functional mitochondrial respiratory chain is now recognized as a reflection of the dynamic association of respiratory complexes in the form of supercomplexes (SCs). Besides providing kinetic advantage (channeling), SCs control ROS generation by the respiratory chain, thus providing a means to regulate ROS levels in the cell. Depending on their concentration, these ROS are either physiological signals essential for the life of the cell or toxic species that damage cell structure and functions. CRITICAL ISSUES We propose that under physiological conditions the dynamic nature of SCs reversibly controls the generation of ROS as signals involved in mitochondrial-nuclear communication. During aging, there is a progressive loss of control of ROS generation so that their production is irreversibly enhanced, inducing a vicious circle in which signaling is altered and structural damage takes place. FUTURE DIRECTIONS A better understanding on the forces affecting SC association would allow the manipulation of ROS generation, directing these species to their physiological signaling role.
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Affiliation(s)
- Maria Luisa Genova
- Dipartimento di Scienze Biomediche e Neuromotorie, Alma Mater Studiorum-Università di Bologna , Bologna, Italy
| | - Giorgio Lenaz
- Dipartimento di Scienze Biomediche e Neuromotorie, Alma Mater Studiorum-Università di Bologna , Bologna, Italy
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111
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Gaspard GJ, McMaster CR. The mitochondrial quality control protein Yme1 is necessary to prevent defective mitophagy in a yeast model of Barth syndrome. J Biol Chem 2015; 290:9284-98. [PMID: 25688091 DOI: 10.1074/jbc.m115.641878] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Indexed: 11/06/2022] Open
Abstract
The Saccharomyces cerevisiae TAZ1 gene is an orthologue of human TAZ; both encode the protein tafazzin. Tafazzin is a transacylase that transfers acyl chains with unsaturated fatty acids from phospholipids to monolysocardiolipin to generate cardiolipin with unsaturated fatty acids. Mutations in human TAZ cause Barth syndrome, a fatal childhood cardiomyopathy biochemically characterized by reduced cardiolipin mass and increased monolysocardiolipin levels. To uncover cellular processes that require tafazzin to maintain cell health, we performed a synthetic genetic array screen using taz1Δ yeast cells to identify genes whose deletion aggravated its fitness. The synthetic genetic array screen uncovered several mitochondrial cellular processes that require tafazzin. Focusing on the i-AAA protease Yme1, a mitochondrial quality control protein that degrades misfolded proteins, we determined that in cells lacking both Yme1 and Taz1 function, there were substantive mitochondrial ultrastructural defects, ineffective superoxide scavenging, and a severe defect in mitophagy. We identify an important role for the mitochondrial protease Yme1 in the ability of cells that lack tafazzin function to maintain mitochondrial structural integrity and mitochondrial quality control and to undergo mitophagy.
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Affiliation(s)
| | - Christopher R McMaster
- From the Departments of Biochemistry and Molecular Biology and Pharmacology, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
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112
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Lu YW, Claypool SM. Disorders of phospholipid metabolism: an emerging class of mitochondrial disease due to defects in nuclear genes. Front Genet 2015; 6:3. [PMID: 25691889 PMCID: PMC4315098 DOI: 10.3389/fgene.2015.00003] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 01/06/2015] [Indexed: 01/14/2023] Open
Abstract
The human nuclear and mitochondrial genomes co-exist within each cell. While the mitochondrial genome encodes for a limited number of proteins, transfer RNAs, and ribosomal RNAs, the vast majority of mitochondrial proteins are encoded in the nuclear genome. Of the multitude of mitochondrial disorders known to date, only a fifth are maternally inherited. The recent characterization of the mitochondrial proteome therefore serves as an important step toward delineating the nosology of a large spectrum of phenotypically heterogeneous diseases. Following the identification of the first nuclear gene defect to underlie a mitochondrial disorder, a plenitude of genetic variants that provoke mitochondrial pathophysiology have been molecularly elucidated and classified into six categories that impact: (1) oxidative phosphorylation (subunits and assembly factors); (2) mitochondrial DNA maintenance and expression; (3) mitochondrial protein import and assembly; (4) mitochondrial quality control (chaperones and proteases); (5) iron–sulfur cluster homeostasis; and (6) mitochondrial dynamics (fission and fusion). Here, we propose that an additional class of genetic variant be included in the classification schema to acknowledge the role of genetic defects in phospholipid biosynthesis, remodeling, and metabolism in mitochondrial pathophysiology. This seventh class includes a small but notable group of nuclear-encoded proteins whose dysfunction impacts normal mitochondrial phospholipid metabolism. The resulting human disorders present with a diverse array of pathologic consequences that reflect the variety of functions that phospholipids have in mitochondria and highlight the important role of proper membrane homeostasis in mitochondrial biology.
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Affiliation(s)
- Ya-Wen Lu
- Department of Physiology, School of Medicine, Johns Hopkins University Baltimore, MD, USA
| | - Steven M Claypool
- Department of Physiology, School of Medicine, Johns Hopkins University Baltimore, MD, USA
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113
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114
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Koob S, Reichert AS. Novel intracellular functions of apolipoproteins: the ApoO protein family as constituents of the Mitofilin/MINOS complex determines cristae morphology in mitochondria. Biol Chem 2015; 395:285-96. [PMID: 24391192 DOI: 10.1515/hsz-2013-0274] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 12/21/2013] [Indexed: 11/15/2022]
Abstract
Mitochondria exist in a highly dynamic network that is constantly altered by fusion and fission events depending on various factors such as cellular bioenergetic state and cell cycle. Next to this dynamic nature of the organelle, its cristae membrane also undergoes drastic morphological changes upon physiological or pathological alterations. The Mitofilin/mitochondrial inner membrane organizing system (MINOS) complex was recently reported to ensure mitochondrial architecture and crista junction integrity. Several subunits of this complex are linked to a diverse set of neurological human disorders. Recently, two apolipoproteins, ApoO (APOO) and ApoO-like (APOOL) were suggested to represent constituents of the mammalian Mitofilin/MINOS complex. APOOL was shown to bind the mitochondrial phospholipid cardiolipin (CL) and to interact physically with this complex. In this review we highlight the current view on the mammalian Mitofilin/MINOS complex and focus on APOOL and the role of CL in determining cristae morphology. We will discuss possible functions of the Mitofilin/MINOS complex on lipid transport, on assembly of respiratory supercomplexes, on F1FO-ATP synthase organization, on contact site formation, and on trapping CL within the cristae subcompartment.
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115
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Jha BK, Seo I, Kong HH, Suh SI, Suh MH, Baek WK. Tigecycline inhibits proliferation of Acanthamoeba castellanii. Parasitol Res 2015; 114:1189-95. [DOI: 10.1007/s00436-014-4302-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 12/23/2014] [Indexed: 10/24/2022]
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116
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Porras CAM, Bai Y. Respiratory supercomplexes: plasticity and implications. Front Biosci (Landmark Ed) 2015; 20:621-34. [PMID: 25553469 DOI: 10.2741/4327] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The plasticity model of the electron transport chain has slowly begun to replace both the liquid model of free complexes and the solid model of supercomplexes. The plasticity model predicts that respiratory complexes exist and function both as single complexes and as supercomplexes. The advantages of this system is an electron transport train which is able to adapt to changes in its environment. This review will investigate the current body of work on supercomplexes including their assembly, regulation, and plasticity, and particularly their role in the generation of reactive oxygen species and aging.
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Affiliation(s)
- Christina Ann-Marie Porras
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
| | - Yidong Bai
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
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117
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von Stockum S, Giorgio V, Trevisan E, Lippe G, Glick GD, Forte MA, Da-Rè C, Checchetto V, Mazzotta G, Costa R, Szabò I, Bernardi P. F-ATPase of Drosophila melanogaster forms 53-picosiemen (53-pS) channels responsible for mitochondrial Ca2+-induced Ca2+ release. J Biol Chem 2014; 290:4537-4544. [PMID: 25550160 DOI: 10.1074/jbc.c114.629766] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mitochondria of Drosophila melanogaster undergo Ca(2+)-induced Ca(2+) release through a putative channel (mCrC) that has several regulatory features of the permeability transition pore (PTP). The PTP is an inner membrane channel that forms from F-ATPase, possessing a conductance of 500 picosiemens (pS) in mammals and of 300 pS in yeast. In contrast to the PTP, the mCrC of Drosophila is not permeable to sucrose and appears to be selective for Ca(2+) and H(+). We show (i) that like the PTP, the mCrC is affected by the sense of rotation of F-ATPase, by Bz-423, and by Mg(2+)/ADP; (ii) that expression of human cyclophilin D in mitochondria of Drosophila S2R(+) cells sensitizes the mCrC to Ca(2+) but does not increase its apparent size; and (iii) that purified dimers of D. melanogaster F-ATPase reconstituted into lipid bilayers form 53-pS channels activated by Ca(2+) and thiol oxidants and inhibited by Mg(2+)/γ-imino ATP. These findings indicate that the mCrC is the PTP of D. melanogaster and that the signature conductance of F-ATPase channels depends on unique structural features that may underscore specific roles in different species.
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Affiliation(s)
| | | | | | - Giovanna Lippe
- the Department of Food Science, University of Udine, I-33100 Udine, Italy
| | - Gary D Glick
- the Department of Chemistry, Graduate Program in Immunology, University of Michigan, Ann Arbor, Michigan 48109, and
| | - Michael A Forte
- the Vollum Institute, Oregon Health and Sciences University, Portland, Oregon 97239
| | - Caterina Da-Rè
- Biology, University of Padova and Consiglio Nazionale delle Ricerche Neuroscience Institute, I-35131 Padova, Italy
| | - Vanessa Checchetto
- Biology, University of Padova and Consiglio Nazionale delle Ricerche Neuroscience Institute, I-35131 Padova, Italy
| | - Gabriella Mazzotta
- Biology, University of Padova and Consiglio Nazionale delle Ricerche Neuroscience Institute, I-35131 Padova, Italy
| | - Rodolfo Costa
- Biology, University of Padova and Consiglio Nazionale delle Ricerche Neuroscience Institute, I-35131 Padova, Italy
| | - Ildikò Szabò
- Biology, University of Padova and Consiglio Nazionale delle Ricerche Neuroscience Institute, I-35131 Padova, Italy
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118
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Chao YJ, Chang WH, Ting HC, Chao WT, Hsu YHH. Cell cycle arrest and cell survival induce reverse trends of cardiolipin remodeling. PLoS One 2014; 9:e113680. [PMID: 25422939 PMCID: PMC4244155 DOI: 10.1371/journal.pone.0113680] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 10/27/2014] [Indexed: 11/18/2022] Open
Abstract
Cell survival from the arrested state can be a cause of the cancer recurrence. Transition from the arrest state to the growth state is highly regulated by mitochondrial activity, which is related to the lipid compositions of the mitochondrial membrane. Cardiolipin is a critical phospholipid for the mitochondrial integrity and functions. We examined the changes of cardiolipin species by LC-MS in the transition between cell cycle arrest and cell reviving in HT1080 fibrosarcoma cells. We have identified 41 cardiolipin species by MS/MS and semi-quantitated them to analyze the detailed changes of cardiolipin species. The mass spectra of cardiolipin with the same carbon number form an envelope, and the C64, C66, C68, C70 C72 and C74 envelopes in HT1080 cells show a normal distribution in the full scan mass spectrum. The cardiolipin quantity in a cell decreases while entering the cell cycle arrest, but maintains at a similar level through cell survival. While cells awakening from the arrested state and preparing itself for replication, the groups with short acyl chains, such as C64, C66 and C68 show a decrease of cardiolipin percentage, but the groups with long acyl chains, such as C70 and C72 display an increase of cardiolipin percentage. Interestingly, the trends of the cardiolipin species changes during the arresting state are completely opposite to cell growing state. Our results indicate that the cardiolipin species shift from the short chain to long chain cardiolipin during the transition from cell cycle arrest to cell progression.
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Affiliation(s)
- Yu-Jen Chao
- Department of Chemistry, Tunghai University, Taichung, Taiwan
| | - Wan-Hsin Chang
- Department of Chemistry, Tunghai University, Taichung, Taiwan
| | - Hsiu-Chi Ting
- Department of Chemistry, Tunghai University, Taichung, Taiwan
| | - Wei-Ting Chao
- Department of Life Science, Tunghai University, Taichung, Taiwan
- Life Science Research Center, Tunghai University, Taichung, Taiwan
| | - Yuan-Hao Howard Hsu
- Department of Chemistry, Tunghai University, Taichung, Taiwan
- Life Science Research Center, Tunghai University, Taichung, Taiwan
- * E-mail:
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119
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Abstract
Beyond their contribution to basic metabolism, the major cellular organelles, in particular mitochondria, can determine whether cells respond to stress in an adaptive or suicidal manner. Thus, mitochondria can continuously adapt their shape to changing bioenergetic demands as they are subjected to quality control by autophagy, or they can undergo a lethal permeabilization process that initiates apoptosis. Along similar lines, multiple proteins involved in metabolic circuitries, including oxidative phosphorylation and transport of metabolites across membranes, may participate in the regulated or catastrophic dismantling of organelles. Many factors that were initially characterized as cell death regulators are now known to physically or functionally interact with metabolic enzymes. Thus, several metabolic cues regulate the propensity of cells to activate self-destructive programs, in part by acting on nutrient sensors. This suggests the existence of "metabolic checkpoints" that dictate cell fate in response to metabolic fluctuations. Here, we discuss recent insights into the intersection between metabolism and cell death regulation that have major implications for the comprehension and manipulation of unwarranted cell loss.
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Affiliation(s)
- Douglas R Green
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
| | - Lorenzo Galluzzi
- Equipe 11 labellisée par la Ligue Nationale contre le Cancer, Centre de Recherche des Cordeliers, F-75006 Paris, France. Université Paris Descartes/Paris V; Sorbonne Paris Cité; F-75005 Paris, France. INSERM, U1138, F-94805 Villejuif, France
| | - Guido Kroemer
- Equipe 11 labellisée par la Ligue Nationale contre le Cancer, Centre de Recherche des Cordeliers, F-75006 Paris, France. Université Paris Descartes/Paris V; Sorbonne Paris Cité; F-75005 Paris, France. INSERM, U1138, F-94805 Villejuif, France. Metabolomics and Cell Biology Platforms, Gustave Roussy, F-94805 Villejuif, France. Pôle de Biologie, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, F-75015 Paris, France.
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120
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Functional role of mitochondrial respiratory supercomplexes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:427-43. [DOI: 10.1016/j.bbabio.2013.11.002] [Citation(s) in RCA: 224] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 10/30/2013] [Accepted: 11/02/2013] [Indexed: 12/30/2022]
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121
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Birk AV, Chao WM, Bracken C, Warren JD, Szeto HH. Targeting mitochondrial cardiolipin and the cytochrome c/cardiolipin complex to promote electron transport and optimize mitochondrial ATP synthesis. Br J Pharmacol 2014; 171:2017-28. [PMID: 24134698 PMCID: PMC3976619 DOI: 10.1111/bph.12468] [Citation(s) in RCA: 217] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2013] [Revised: 09/19/2013] [Accepted: 10/09/2013] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND AND PURPOSE Cardiolipin plays an important role in mitochondrial respiration and cardiolipin peroxidation is associated with age-related diseases. Hydrophobic interactions between cytochrome c and cardiolipin converts cytochrome c from an electron carrier to a peroxidase. In addition to cardiolipin peroxidation, this impedes electron flux and inhibits mitochondrial ATP synthesis. SS-31 (D-Arg-dimethylTyr-Lys-Phe-NH2 ) selectively binds to cardiolipin and inhibits cytochrome c peroxidase activity. Here, we examined whether SS-31 also protected the electron carrier function of cytochrome c. EXPERIMENTAL APPROACH Interactions of SS-31 with cardiolipin were studied using liposomes and bicelles containing phosphatidylcholine alone or with cardiolipin. Structural interactions were assessed by fluorescence spectroscopy, turbidity and nuclear magnetic resonance. Effects of cardiolipin on electron transfer kinetics of cytochrome c were determined by cytochrome c reduction in vitro and oxygen consumption using mitoplasts, frozen and fresh mitochondria. KEY RESULTS SS-31 interacted only with liposomes and bicelles containing cardiolipin in about 1:1 ratio. NMR studies demonstrated that the aromatic residues of SS-31 penetrated deep into cardiolipin-containing bilayers. SS-31 restored cytochrome c reduction and mitochondrial oxygen consumption in the presence of added cardiolipin. In fresh mitochondria, SS-31 increased state 3 respiration and efficiency of ATP synthesis. CONCLUSIONS AND IMPLICATIONS SS-31 selectively targeted cardiolipin and modulated its interaction with cytochrome c. SS-31 inhibited the cytochrome c/cardiolipin complex peroxidase activity while protecting its ability to serve as an electron carrier, thus optimizing mitochondrial electron transport and ATP synthesis. This novel class of cardiolipin therapeutics has the potential to restore mitochondrial bioenergetics for treatment of numerous age-related diseases.
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Affiliation(s)
- A V Birk
- Department of Pharmacology, Joan and Sanford I. Weill Medical College of Cornell UniversityNew York, NY, USA
| | - W M Chao
- Department of Pharmacology, Joan and Sanford I. Weill Medical College of Cornell UniversityNew York, NY, USA
| | - C Bracken
- Department of Biochemistry, Joan and Sanford I. Weill Medical College of Cornell UniversityNew York, NY, USA
- Nuclear Magnetic Resonance Core Facility, Joan and Sanford I. Weill Medical College of Cornell UniversityNew York, NY, USA
| | - J D Warren
- Department of Biochemistry, Joan and Sanford I. Weill Medical College of Cornell UniversityNew York, NY, USA
- Milstein Chemistry Core Facility, Joan and Sanford I. Weill Medical College of Cornell UniversityNew York, NY, USA
| | - H H Szeto
- Department of Pharmacology, Joan and Sanford I. Weill Medical College of Cornell UniversityNew York, NY, USA
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122
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Hishikawa D, Hashidate T, Shimizu T, Shindou H. Diversity and function of membrane glycerophospholipids generated by the remodeling pathway in mammalian cells. J Lipid Res 2014; 55:799-807. [PMID: 24646950 PMCID: PMC3995458 DOI: 10.1194/jlr.r046094] [Citation(s) in RCA: 230] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Cellular membranes are composed of numerous kinds of glycerophospholipids with different combinations of polar heads at the sn-3 position and acyl moieties at the sn-1 and sn-2 positions, respectively. The glycerophospholipid compositions of different cell types, organelles, and inner/outer plasma membrane leaflets are quite diverse. The acyl moieties of glycerophospholipids synthesized in the de novo pathway are subsequently remodeled by the action of phospholipases and lysophospholipid acyltransferases. This remodeling cycle contributes to the generation of membrane glycerophospholipid diversity and the production of lipid mediators such as fatty acid derivatives and lysophospholipids. Furthermore, specific glycerophospholipid transporters are also important to organize a unique glycerophospholipid composition in each organelle. Recent progress in this field contributes to understanding how and why membrane glycerophospholipid diversity is organized and maintained.
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Affiliation(s)
- Daisuke Hishikawa
- Department of Lipid Signaling, Research Institute, National Center for Global Health and Medicine, Tokyo 162-8655, Japan
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123
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Acin-Perez R, Enriquez JA. The function of the respiratory supercomplexes: the plasticity model. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1837:444-50. [PMID: 24368156 DOI: 10.1016/j.bbabio.2013.12.009] [Citation(s) in RCA: 206] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Revised: 12/12/2013] [Accepted: 12/17/2013] [Indexed: 01/16/2023]
Abstract
Mitochondria are important organelles not only as efficient ATP generators but also in controlling and regulating many cellular processes. Mitochondria are dynamic compartments that rearrange under stress response and changes in food availability or oxygen concentrations. The mitochondrial electron transport chain parallels these rearrangements to achieve an optimum performance and therefore requires a plastic organization within the inner mitochondrial membrane. This consists in a balanced distribution between free respiratory complexes and supercomplexes. The mechanisms by which the distribution and organization of supercomplexes can be adjusted to the needs of the cells are still poorly understood. The aim of this review is to focus on the functional role of the respiratory supercomplexes and its relevance in physiology. This article is part of a Special Issue entitled: Dynamic and ultrastructure of bioenergetic membranes and their components.
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Affiliation(s)
- Rebeca Acin-Perez
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Melchor Fernández Almagro, 3, 28029 Madrid, Spain
| | - Jose A Enriquez
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Melchor Fernández Almagro, 3, 28029 Madrid, Spain.
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124
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Baile MG, Sathappa M, Lu YW, Pryce E, Whited K, McCaffery JM, Han X, Alder NN, Claypool SM. Unremodeled and remodeled cardiolipin are functionally indistinguishable in yeast. J Biol Chem 2013; 289:1768-78. [PMID: 24285538 DOI: 10.1074/jbc.m113.525733] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
After biosynthesis, an evolutionarily conserved acyl chain remodeling process generates a final highly homogeneous and yet tissue-specific molecular form of the mitochondrial lipid cardiolipin. Hence, cardiolipin molecules in different organisms, and even different tissues within the same organism, contain a distinct collection of attached acyl chains. This observation is the basis for the widely accepted paradigm that the acyl chain composition of cardiolipin is matched to the unique mitochondrial demands of a tissue. For this hypothesis to be correct, cardiolipin molecules with different acyl chain compositions should have distinct functional capacities, and cardiolipin that has been remodeled should promote cardiolipin-dependent mitochondrial processes better than its unremodeled form. However, functional disparities between different molecular forms of cardiolipin have never been established. Here, we interrogate this simple but crucial prediction utilizing the best available model to do so, Saccharomyces cerevisiae. Specifically, we compare the ability of unremodeled and remodeled cardiolipin, which differ markedly in their acyl chain composition, to support mitochondrial activities known to require cardiolipin. Surprisingly, defined changes in the acyl chain composition of cardiolipin do not alter either mitochondrial morphology or oxidative phosphorylation. Importantly, preventing cardiolipin remodeling initiation in yeast lacking TAZ1, an ortholog of the causative gene in Barth syndrome, ameliorates mitochondrial dysfunction. Thus, our data do not support the prevailing hypothesis that unremodeled cardiolipin is functionally distinct from remodeled cardiolipin, at least for the functions examined, suggesting alternative physiological roles for this conserved pathway.
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Affiliation(s)
- Matthew G Baile
- From the Department of Physiology, The Johns Hopkins School of Medicine, Baltimore, Maryland 21205
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125
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Cardiolipin-dependent formation of mitochondrial respiratory supercomplexes. Chem Phys Lipids 2013; 179:42-8. [PMID: 24220496 DOI: 10.1016/j.chemphyslip.2013.10.012] [Citation(s) in RCA: 182] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2013] [Revised: 10/21/2013] [Accepted: 10/30/2013] [Indexed: 11/20/2022]
Abstract
The organization of individual respiratory Complexes I, III, and IV (mammalian cells) or III and IV (yeast) of the mitochondria into higher order supercomplexes (SCs) is generally accepted. However, the factors that regulate SC formation and the functional significance of SCs are not well understood. The mitochondrial signature phospholipid cardiolipin (CL) plays a central role in formation and stability of respiratory SCs from yeast to man. Studies in yeast mutants in which the CL level can be regulated displayed a direct correlation between CL levels and SC formation. Disease states in which CL levels are reduced also show defects in SC formation. Three-dimensional density maps of yeast and bovine SCs by electron cryo-microscopy show gaps between the transmembrane-localized interfaces of individual complexes consistent with the large excess of CL in SCs over that integrated into the structure of individual respiratory complexes. Finally, the yeast SC composed of Complex III and two Complexes IV was reconstituted in liposomes from purified individual complexes containing integrated CLs. Reconstitution was wholly dependent on inclusion of additional CL in the liposomes. Therefore, non-integral CL molecules play an important role in SC formation and may be involved in regulation of SC stability under metabolic conditions where CL levels fluctuate.
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126
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Baile MG, Whited K, Claypool SM. Deacylation on the matrix side of the mitochondrial inner membrane regulates cardiolipin remodeling. Mol Biol Cell 2013; 24:2008-20. [PMID: 23637464 PMCID: PMC3681703 DOI: 10.1091/mbc.e13-03-0121] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Our understanding of the clinically relevant tafazzin-mediated cardiolipin (CL) remodeling pathway is incomplete. In this study, a new trafficking step required for CL remodeling has been identified. Further, it is demonstrated that flux through this CL remodeling pathway is controlled by the strength of the mitochondrial electrochemical gradient. The mitochondrial-specific lipid cardiolipin (CL) is required for numerous processes therein. After its synthesis on the matrix-facing leaflet of the inner membrane (IM), CL undergoes acyl chain remodeling to achieve its final form. In yeast, this process is completed by the transacylase tafazzin, which associates with intermembrane space (IMS)-facing membrane leaflets. Mutations in TAZ1 result in the X-linked cardiomyopathy Barth syndrome. Amazingly, despite this clear pathophysiological association, the physiological importance of CL remodeling is unresolved. In this paper, we show that the lipase initiating CL remodeling, Cld1p, is associated with the matrix-facing leaflet of the mitochondrial IM. Thus monolysocardiolipin generated by Cld1p must be transported to IMS-facing membrane leaflets to gain access to tafazzin, identifying a previously unknown step required for CL remodeling. Additionally, we show that Cld1p is the major site of regulation in CL remodeling; and that, like CL biosynthesis, CL remodeling is augmented in growth conditions requiring mitochondrially produced energy. However, unlike CL biosynthesis, dissipation of the mitochondrial membrane potential stimulates CL remodeling, identifying a novel feedback mechanism linking CL remodeling to oxidative phosphorylation capacity.
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Affiliation(s)
- Matthew G Baile
- Department of Physiology, Johns Hopkins School of Medicine, Baltimore, MD 21205-2185, USA
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