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Woyda-Ploszczyca AM. Direct and indirect targets of carboxyatractyloside, including overlooked toxicity toward nucleoside diphosphate kinase (NDPK) and mitochondrial H + leak. PHARMACEUTICAL BIOLOGY 2023; 61:372-390. [PMID: 36799406 PMCID: PMC9946330 DOI: 10.1080/13880209.2023.2168704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 12/30/2022] [Accepted: 01/10/2023] [Indexed: 06/18/2023]
Abstract
CONTEXT The toxicity of atractyloside/carboxyatractyloside is generally well recognized and commonly ascribed to the inhibition of mitochondrial ADP/ATP carriers, which are pivotal for oxidative phosphorylation. However, these glycosides may 'paralyze' additional target proteins. OBJECTIVE This review presents many facts about atractyloside/carboxyatractyloside and their plant producers, such as Xanthium spp. (Asteraceae), named cockleburs. METHODS Published studies and other information were obtained from databases, such as 'CABI - Invasive Species Compendium', 'PubMed', and 'The World Checklist of Vascular Plants', from 1957 to December 2022. The following major keywords were used: 'carboxyatractyloside', 'cockleburs', 'hepatotoxicity', 'mitochondria', 'nephrotoxicity', and 'Xanthium'. RESULTS In the third decade of the twenty first century, public awareness of the severe toxicity of cockleburs is still limited. Such toxicity is often only perceived by specialists in Europe and other continents. Interestingly, cocklebur is among the most widely distributed invasive plants worldwide, and the recognition of new European stands of Xanthium spp. is provided here. The findings arising from field and laboratory research conducted by the author revealed that (i) some livestock populations may instinctively avoid eating cocklebur while grazing, (ii) carboxyatractyloside inhibits ADP/GDP metabolism, and (iii) the direct/indirect target proteins of carboxyatractyloside are ambiguous. CONCLUSIONS Many aspects of the Xanthium genus still require substantial investigation/revision in the future, such as the unification of the Latin nomenclature of currently distinguished species, bur morphology status, true fruit (achene) description and biogeography of cockleburs, and a detailed description of the physiological roles of atractyloside/carboxyatractyloside and the toxicity of these glycosides, mainly toward mammals. Therefore, a more careful interpretation of atractyloside/carboxyatractyloside data, including laboratory tests using Xanthium-derived extracts and purified toxins, is needed.
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Wu CHW, Caha M, Smoot L, Harris DJ, Roberts AE, Sacharow S, Bodamer O. Sengers syndrome and AGK-related disorders - Minireview of phenotypic variability and clinical outcomes in molecularly confirmed cases. Mol Genet Metab 2023; 139:107626. [PMID: 37354892 DOI: 10.1016/j.ymgme.2023.107626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2023] [Revised: 05/17/2023] [Accepted: 05/31/2023] [Indexed: 06/26/2023]
Abstract
Sengers syndrome (OMIM# 212350) is a rare autosomal recessive mitochondrial disease caused by biallelic pathogenic variants in the AGK gene, which encodes the acylglycerol kinase enzyme. The syndrome was originally defined as a "triad" of hypertrophic cardiomyopathy, cataracts, and lactic acidosis, with or without skeletal myopathy. The clinical manifestation of Sengers Syndrome exhibits substantial heterogeneity, with mild and severe/infantile forms reported. Further, biallelic AGK pathogenic variants have also been identified in a familial case of non-syndromic isolated cataract (OMIM# 614691), expanding our understanding of the gene's influence beyond the originally defined syndrome. In this study, we provide a systematic review of molecularly confirmed cases with biallelic AGK pathogenic variants (Supplementary Table 1). Our analysis demonstrates the variable expressivity and penetrance of the central features of Sengers syndrome, as follows: cataracts (98%), cardiomyopathy (88%), lactic acidosis (adjusted 88%), and skeletal myopathy (adjusted 74%) (Table 1). Furthermore, we investigate the associations between genotype, biochemical profiles, and clinical outcomes, with a particular focus on infantile mortality. Our findings reveal that patients carrying homozygous nonsense variants have a higher incidence of infant mortality and a lower median age of death (p = 0.005 and p = 0.02, Table 2a). However, the location of pathogenic variants within the AGK domains was not significantly associated with infantile death (p = 0.62, Table 2b). Additionally, we observe a borderline association between the absence of lactic acidosis and longer survival (p = 0.053, Table 2c). Overall, our systematic review sheds light on the diverse clinical manifestations of AGK-related disorders and highlights potential factors that influence its prognosis. These provide important implications for the diagnosis, treatment, and counseling of affected individuals and families.
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Affiliation(s)
- Chen-Han Wilfred Wu
- Division of Genetics and Genomics, Department of Medicine, Boston Children's Hospital/Harvard Medical School, United States; Department of Genetics and Genome Sciences, Case Western Reserve University and University Hospitals, United States; Department of Urology, Case Western Reserve University and University Hospitals, United States.
| | - Martin Caha
- Department of Pediatrics, SUNY Downstate Health Sciences University, United States
| | - Leslie Smoot
- Department of Cardiology, Boston Children's Hospital/Harvard Medical School, United States
| | - David J Harris
- Division of Genetics and Genomics, Department of Medicine, Boston Children's Hospital/Harvard Medical School, United States
| | - Amy E Roberts
- Division of Genetics and Genomics, Department of Medicine, Boston Children's Hospital/Harvard Medical School, United States; Department of Cardiology, Boston Children's Hospital/Harvard Medical School, United States
| | - Stephanie Sacharow
- Division of Genetics and Genomics, Department of Medicine, Boston Children's Hospital/Harvard Medical School, United States
| | - Olaf Bodamer
- Division of Genetics and Genomics, Department of Medicine, Boston Children's Hospital/Harvard Medical School, United States
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Chen Y, Wu L, Liu J, Ma L, Zhang W. Adenine nucleotide translocase: Current knowledge in post-translational modifications, regulations and pathological implications for human diseases. FASEB J 2023; 37:e22953. [PMID: 37224026 DOI: 10.1096/fj.202201855rr] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 04/01/2023] [Accepted: 04/25/2023] [Indexed: 05/26/2023]
Abstract
Adenine nucleotide translocases (ANTs) are central to mitochondrial integrity and bioenergetic metabolism. This review aims to integrate the progresses and knowledge on ANTs over the last few years, contributing to a potential implication of ANTs for various diseases. Structures, functions, modifications, regulators and pathological implications of ANTs for human diseases are intensively demonstrated here. ANTs have four isoforms (ANT1-4), responsible for exchanging ATP/ADP, possibly composing of pro-apoptotic mPTP as a major component, and mediating FA-dependent uncoupling of proton efflux. ANT can be modified by methylation, nitrosylation and nitroalkylation, acetylation, glutathionylation, phosphorylation, carbonylation and hydroxynonenal-induced modifications. Compounds, including bongkrekic acid, atractyloside calcium, carbon monoxide, minocycline, 4-(N-(S-penicillaminylacetyl)amino) phenylarsonous acid, cardiolipin, free long-chain fatty acids, agaric acid, long chain acyl-coenzyme A esters, all have an ability to regulate ANT activities. ANT impairment leads to bioenergetic failure and mitochondrial dysfunction, contributing to pathogenesis of diseases, such as diabetes (deficiency), heart disease (deficiency), Parkinson's disease (reduction), Sengers Syndrome (decrease), cancer (isoform shifting), Alzheimer's Disease (coaggregation with Tau), Progressive External Opthalmoplegia (mutation), and Fascioscapulohumeral muscular dystrophy (overexpression). This review improves the understanding of the mechanism of ANT in pathogenesis of human diseases, and opens a window for novel therapeutic strategies targeted on ANT in diseases.
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Affiliation(s)
- Yingfei Chen
- Grade 2020, Capital Medical University, Beijing, China
| | - Leshuang Wu
- Grade 2019, Dalian Medical University, Dalian, China
| | - Jun Liu
- Department of Epidemiology, Dalian Medical University, Dalian, China
| | - Li Ma
- Department of Epidemiology, Dalian Medical University, Dalian, China
| | - Wenli Zhang
- Biochemistry and Molecular Biology Department of College of Basic Medical Sciences, Dalian Medical University, Dalian, China
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4
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A novel AGK splicing mutation in a patient with Sengers syndrome and left ventricular non-compaction cardiomyopathy. Pediatr Res 2023:10.1038/s41390-023-02515-3. [PMID: 36759750 DOI: 10.1038/s41390-023-02515-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 12/16/2022] [Accepted: 01/21/2023] [Indexed: 02/11/2023]
Abstract
BACKGROUND Sengers syndrome characterized by hypertrophic cardiomyopathy is an extremely rare genetic disorder. Sengers syndrome associated with left ventricular non-compaction (LVNC) has not been described. METHODS Genetic testing was used to identify candidate AGK variants in the proband. The predicted molecular structures were constructed by protein modeling. Exon skipping caused by the identified splicing mutations was verified by in silico analyses and in vitro assays. The genotypic and phenotypic features of patients with AGK splicing mutations were extracted by a systematic review. RESULTS The proband was characterized by Sengers syndrome and LVNC and caused by a novel compound heterozygous AGK splicing mutation. This compound mutation simultaneously perturbed the protein sequences and spatial conformation of the acylglycerol kinase protein. In silico and in vitro analyses demonstrated skipping of exons 7 and 8 and premature truncation as a result of exon 8 skipping. The systematic review indicated that patients with an AGK splicing mutation may have milder phenotypes of Sengers syndrome. CONCLUSIONS The genotypic and phenotypic spectrums of Sengers syndrome have been expanded, which will provide essential information for genetic counseling. The molecular mechanism in AGK mutations can offer insights into the potential targets for treatment. IMPACT First description of a child with Sengers syndrome and left ventricular non-compaction cardiomyopathy. A novel pathogenic compound heterozygous splicing mutation in AGK for Sengers syndrome was identified. The identified mutations led to exons skipping by in silico analyses and in vitro assays.
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Successful Anesthetic Management of Mitochondrial Myopathy and Hypertrophic Obstructive Cardiomyopathy in a Child With Senger Syndrome. Am J Ther 2022; 29:e651-e652. [PMID: 35994379 DOI: 10.1097/mjt.0000000000001557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Panicucci C, Schiaffino MC, Nesti C, Derchi M, Trocchio G, Severino M, Stagnaro N, Priolo E, Zara F, Santorelli FM, Bruno C. Long term follow-up in two siblings with Sengers syndrome: Case report. Ital J Pediatr 2022; 48:180. [PMID: 36253788 PMCID: PMC9575244 DOI: 10.1186/s13052-022-01370-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 07/28/2022] [Accepted: 09/13/2022] [Indexed: 11/24/2022] Open
Abstract
Background Sengers syndrome is characterized by congenital cataract, hypertrophic cardiomyopathy, mitochondrial myopathy, and lactic acidosis associated with mutations in AGK gene. Clinical course ranges from a severe fatal neonatal form, to a more benign form allowing survival into adulthood, to an isolated form of congenital cataract. Thus far few reported cases have survived the second decade at their latest examination, and no natural history data are available for the disease. Case presentation Here we provide a 20-year follow-up in two siblings with a benign form of Sengers syndrome, expanding the phenotypical spectrum of the disease by reporting a condition of ovarian agenesis. Conclusion To our knowledge, this report provides the first longitudinal data of Sengers syndrome patients. Supplementary information The online version contains supplementary material available at 10.1186/s13052-022-01370-y.
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Affiliation(s)
- Chiara Panicucci
- Center of Translational and Experimental Myology, IRCCS Istituto Giannina Gaslini, Via G. Gaslini, 5, I-16147, Genova, Italy
| | | | - Claudia Nesti
- Molecular Medicine, IRCCS Stella Maris Foundation, Pisa, Italy
| | - Maria Derchi
- Cardiology Unit, IRCCS Istituto Giannina Gaslini, Genova, Italy
| | | | | | - Nicola Stagnaro
- Radiology Unit, IRCCS Istituto Giannina Gaslini, Genova, Italy
| | - Enrico Priolo
- Ophthalmology Unit, IRCCS Istituto Giannina Gaslini, Genova, Italy
| | - Federico Zara
- Medical Genetics Unit, IRCCS Istituto Giannina Gaslini, Genova, Italy.,Department of Neurology, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genova, Genova, Italy
| | | | - Claudio Bruno
- Center of Translational and Experimental Myology, IRCCS Istituto Giannina Gaslini, Via G. Gaslini, 5, I-16147, Genova, Italy. .,Department of Neurology, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genova, Genova, Italy.
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Characterization of a Novel Splicing Variant in Acylglycerol Kinase (AGK) Associated with Fatal Sengers Syndrome. Int J Mol Sci 2021; 22:ijms222413484. [PMID: 34948281 PMCID: PMC8708263 DOI: 10.3390/ijms222413484] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Revised: 12/09/2021] [Accepted: 12/13/2021] [Indexed: 12/26/2022] Open
Abstract
Mitochondrial functional integrity depends on protein and lipid homeostasis in the mitochondrial membranes and disturbances in their accumulation can cause disease. AGK, a mitochondrial acylglycerol kinase, is not only involved in lipid signaling but is also a component of the TIM22 complex in the inner mitochondrial membrane, which mediates the import of a subset of membrane proteins. AGK mutations can alter both phospholipid metabolism and mitochondrial protein biogenesis, contributing to the pathogenesis of Sengers syndrome. We describe the case of an infant carrying a novel homozygous AGK variant, c.518+1G>A, who was born with congenital cataracts, pielic ectasia, critical congenital dilated myocardiopathy, and hyperlactacidemia and died 20 h after birth. Using the patient’s DNA, we performed targeted sequencing of 314 nuclear genes encoding respiratory chain complex subunits and proteins implicated in mitochondrial oxidative phosphorylation (OXPHOS). A decrease of 96-bp in the length of the AGK cDNA sequence was detected. Decreases in the oxygen consumption rate (OCR) and the OCR:ECAR (extracellular acidification rate) ratio in the patient’s fibroblasts indicated reduced electron flow through the respiratory chain, and spectrophotometry revealed decreased activity of OXPHOS complexes I and V. We demonstrate a clear defect in mitochondrial function in the patient’s fibroblasts and describe the possible molecular mechanism underlying the pathogenicity of this novel AGK variant. Experimental validation using in vitro analysis allowed an accurate characterization of the disease-causing variant.
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Yergöz F, Friebel J, Kränkel N, Rauch-Kroehnert U, Schultheiss HP, Landmesser U, Dörner A. Adenine Nucleotide Translocase 1 Expression Modulates the Immune Response in Ischemic Hearts. Cells 2021; 10:cells10082130. [PMID: 34440901 PMCID: PMC8393693 DOI: 10.3390/cells10082130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Revised: 08/16/2021] [Accepted: 08/17/2021] [Indexed: 11/16/2022] Open
Abstract
Adenine nucleotide translocase 1 (ANT1) transfers ATP and ADP over the mitochondrial inner membrane and thus supplies the cell with energy. This study analyzed the role of ANT1 in the immune response of ischemic heart tissue. Ischemic ANT1 overexpressing hearts experienced a shift toward an anti-inflammatory immune response. The shift was characterized by low interleukin (IL)-1β expression and M1 macrophage infiltration, whereas M2 macrophage infiltration and levels of IL-10, IL-4, and transforming growth factor (TGFβ) were increased. The modulated immune response correlated with high mitochondrial integrity, reduced oxidative stress, low left ventricular end-diastolic heart pressure, and a high survival rate. Isolated ANT1-transgenic (ANT1-TG) cardiomyocytes expressed low levels of pro-inflammatory cytokines such as IL-1α, tumor necrosis factor α, and TGFβ. However, they showed increased expression and cellular release of anti-inflammatory immunomodulators such as vascular endothelial growth factor. The secretome from ANT1-TG cardiomyocytes initiated stress resistance when applied to ischemic wild-type cardiomyocytes and endothelial cells. It additionally prevented macrophages from expressing pro-inflammatory cytokines. Additionally, ANT1 expression correlated with genes that are related to cytokine and growth factor pathways in hearts of patients with ischemic cardiomyopathy. In conclusion, ANT1-TG cardiomyocytes secrete soluble factors that influence ischemic cardiac cells and initiate an anti-inflammatory immune response in ischemic hearts.
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Affiliation(s)
- Fatih Yergöz
- Department of Cardiology, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, 12200 Berlin, Germany; (F.Y.); (J.F.); (N.K.); (U.R.-K.); (U.L.)
- Institute of Health Center for Regenerative Therapies (BCRT), Charité—Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Julian Friebel
- Department of Cardiology, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, 12200 Berlin, Germany; (F.Y.); (J.F.); (N.K.); (U.R.-K.); (U.L.)
- DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, 10785 Berlin, Germany
| | - Nicolle Kränkel
- Department of Cardiology, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, 12200 Berlin, Germany; (F.Y.); (J.F.); (N.K.); (U.R.-K.); (U.L.)
- DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, 10785 Berlin, Germany
| | - Ursula Rauch-Kroehnert
- Department of Cardiology, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, 12200 Berlin, Germany; (F.Y.); (J.F.); (N.K.); (U.R.-K.); (U.L.)
- DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, 10785 Berlin, Germany
| | | | - Ulf Landmesser
- Department of Cardiology, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, 12200 Berlin, Germany; (F.Y.); (J.F.); (N.K.); (U.R.-K.); (U.L.)
- Institute of Health Center for Regenerative Therapies (BCRT), Charité—Universitätsmedizin Berlin, 13353 Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, 10785 Berlin, Germany
| | - Andrea Dörner
- Department of Cardiology, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, 12200 Berlin, Germany; (F.Y.); (J.F.); (N.K.); (U.R.-K.); (U.L.)
- DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, 10785 Berlin, Germany
- Correspondence: ; Tel.: +49-30-450-513-727
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Chaudhuri M, Tripathi A, Gonzalez FS. Diverse Functions of Tim50, a Component of the Mitochondrial Inner Membrane Protein Translocase. Int J Mol Sci 2021; 22:7779. [PMID: 34360547 PMCID: PMC8346121 DOI: 10.3390/ijms22157779] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 07/14/2021] [Accepted: 07/16/2021] [Indexed: 12/17/2022] Open
Abstract
Mitochondria are essential in eukaryotes. Besides producing 80% of total cellular ATP, mitochondria are involved in various cellular functions such as apoptosis, inflammation, innate immunity, stress tolerance, and Ca2+ homeostasis. Mitochondria are also the site for many critical metabolic pathways and are integrated into the signaling network to maintain cellular homeostasis under stress. Mitochondria require hundreds of proteins to perform all these functions. Since the mitochondrial genome only encodes a handful of proteins, most mitochondrial proteins are imported from the cytosol via receptor/translocase complexes on the mitochondrial outer and inner membranes known as TOMs and TIMs. Many of the subunits of these protein complexes are essential for cell survival in model yeast and other unicellular eukaryotes. Defects in the mitochondrial import machineries are also associated with various metabolic, developmental, and neurodegenerative disorders in multicellular organisms. In addition to their canonical functions, these protein translocases also help maintain mitochondrial structure and dynamics, lipid metabolism, and stress response. This review focuses on the role of Tim50, the receptor component of one of the TIM complexes, in different cellular functions, with an emphasis on the Tim50 homologue in parasitic protozoan Trypanosoma brucei.
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Affiliation(s)
- Minu Chaudhuri
- Department of Microbiology, Immunology, and Physiology, Meharry Medical College, Nashville, TN 37208, USA; (A.T.); (F.S.G.)
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Kunji ERS, King MS, Ruprecht JJ, Thangaratnarajah C. The SLC25 Carrier Family: Important Transport Proteins in Mitochondrial Physiology and Pathology. Physiology (Bethesda) 2021; 35:302-327. [PMID: 32783608 PMCID: PMC7611780 DOI: 10.1152/physiol.00009.2020] [Citation(s) in RCA: 77] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Members of the mitochondrial carrier family (SLC25) transport a variety of compounds across the inner membrane of mitochondria. These transport steps provide building blocks for the cell and link the pathways of the mitochondrial matrix and cytosol. An increasing number of diseases and pathologies has been associated with their dysfunction. In this review, the molecular basis of these diseases is explained based on our current understanding of their transport mechanism.
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Affiliation(s)
- Edmund R S Kunji
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Martin S King
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Jonathan J Ruprecht
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Chancievan Thangaratnarajah
- Groningen Biomolecular Sciences and Biotechnology Institute, Membrane Enzymology, University of Groningen, Groningen, The Netherlands
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11
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Molecular Insights into Mitochondrial Protein Translocation and Human Disease. Genes (Basel) 2021; 12:genes12071031. [PMID: 34356047 PMCID: PMC8305315 DOI: 10.3390/genes12071031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 06/27/2021] [Accepted: 06/30/2021] [Indexed: 12/11/2022] Open
Abstract
In human mitochondria, mtDNA encodes for only 13 proteins, all components of the OXPHOS system. The rest of the mitochondrial components, which make up approximately 99% of its proteome, are encoded in the nuclear genome, synthesized in cytosolic ribosomes and imported into mitochondria. Different import machineries translocate mitochondrial precursors, depending on their nature and the final destination inside the organelle. The proper and coordinated function of these molecular pathways is critical for mitochondrial homeostasis. Here, we will review molecular details about these pathways, which components have been linked to human disease and future perspectives on the field to expand the genetic landscape of mitochondrial diseases.
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12
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The mitochondrial ADP/ATP carrier exists and functions as a monomer. Biochem Soc Trans 2021; 48:1419-1432. [PMID: 32725219 PMCID: PMC7458400 DOI: 10.1042/bst20190933] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 06/26/2020] [Accepted: 07/06/2020] [Indexed: 12/15/2022]
Abstract
For more than 40 years, the oligomeric state of members of the mitochondrial carrier family (SLC25) has been the subject of debate. Initially, the consensus was that they were dimeric, based on the application of a large number of different techniques. However, the structures of the mitochondrial ADP/ATP carrier, a member of the family, clearly demonstrated that its structural fold is monomeric, lacking a conserved dimerisation interface. A re-evaluation of previously published data, with the advantage of hindsight, concluded that technical errors were at the basis of the earlier dimer claims. Here, we revisit this topic, as new claims for the existence of dimers of the bovine ADP/ATP carrier have emerged using native mass spectrometry of mitochondrial membrane vesicles. However, the measured mass does not agree with previously published values, and a large number of post-translational modifications are proposed to account for the difference. Contrarily, these modifications are not observed in electron density maps of the bovine carrier. If they were present, they would interfere with the structure and function of the carrier, including inhibitor and substrate binding. Furthermore, the reported mass does not account for three tightly bound cardiolipin molecules, which are consistently observed in other studies and are important stabilising factors for the transport mechanism. The monomeric carrier has all of the required properties for a functional transporter and undergoes large conformational changes that are incompatible with a stable dimerisation interface. Thus, our view that the native mitochondrial ADP/ATP carrier exists and functions as a monomer remains unaltered.
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13
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A Walk in the Memory, from the First Functional Approach up to Its Regulatory Role of Mitochondrial Bioenergetic Flow in Health and Disease: Focus on the Adenine Nucleotide Translocator. Int J Mol Sci 2021; 22:ijms22084164. [PMID: 33920595 PMCID: PMC8073645 DOI: 10.3390/ijms22084164] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Revised: 04/11/2021] [Accepted: 04/16/2021] [Indexed: 12/19/2022] Open
Abstract
The mitochondrial adenine nucleotide translocator (ANT) plays the fundamental role of gatekeeper of cellular energy flow, carrying out the reversible exchange of ADP for ATP across the inner mitochondrial membrane. ADP enters the mitochondria where, through the oxidative phosphorylation process, it is the substrate of Fo-F1 ATP synthase, producing ATP that is dispatched from the mitochondrion to the cytoplasm of the host cell, where it can be used as energy currency for the metabolic needs of the cell that require energy. Long ago, we performed a method that allowed us to monitor the activity of ANT by continuously detecting the ATP gradually produced inside the mitochondria and exported in the extramitochondrial phase in exchange with externally added ADP, under conditions quite close to a physiological state, i.e., when oxidative phosphorylation takes place. More than 30 years after the development of the method, here we aim to put the spotlight on it and to emphasize its versatile applicability in the most varied pathophysiological conditions, reviewing all the studies, in which we were able to observe what really happened in the cell thanks to the use of the "ATP detecting system" allowing the functional activity of the ANT-mediated ADP/ATP exchange to be measured.
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14
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Abnormalities of synaptic mitochondria in autism spectrum disorder and related neurodevelopmental disorders. J Mol Med (Berl) 2020; 99:161-178. [PMID: 33340060 PMCID: PMC7819932 DOI: 10.1007/s00109-020-02018-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 11/27/2020] [Accepted: 12/02/2020] [Indexed: 12/18/2022]
Abstract
Autism spectrum disorder (ASD) is a neurodevelopmental condition primarily characterized by an impairment of social interaction combined with the occurrence of repetitive behaviors. ASD starts in childhood and prevails across the lifespan. The variability of its clinical presentation renders early diagnosis difficult. Mutations in synaptic genes and alterations of mitochondrial functions are considered important underlying pathogenic factors, but it is obvious that we are far from a comprehensive understanding of ASD pathophysiology. At the synapse, mitochondria perform diverse functions, which are clearly not limited to their classical role as energy providers. Here, we review the current knowledge about mitochondria at the synapse and summarize the mitochondrial disturbances found in mouse models of ASD and other ASD-related neurodevelopmental disorders, like DiGeorge syndrome, Rett syndrome, Tuberous sclerosis complex, and Down syndrome.
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Metabolic Alterations Caused by Defective Cardiolipin Remodeling in Inherited Cardiomyopathies. Life (Basel) 2020; 10:life10110277. [PMID: 33187128 PMCID: PMC7697959 DOI: 10.3390/life10110277] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 11/04/2020] [Accepted: 11/06/2020] [Indexed: 12/21/2022] Open
Abstract
The heart is the most energy-consuming organ in the human body. In heart failure, the homeostasis of energy supply and demand is endangered by an increase in cardiomyocyte workload, or by an insufficiency in energy-providing processes. Energy metabolism is directly associated with mitochondrial redox homeostasis. The production of toxic reactive oxygen species (ROS) may overwhelm mitochondrial and cellular ROS defense mechanisms in case of heart failure. Mitochondria are essential cell organelles and provide 95% of the required energy in the heart. Metabolic remodeling, changes in mitochondrial structure or function, and alterations in mitochondrial calcium signaling diminish mitochondrial energy provision in many forms of cardiomyopathy. The mitochondrial respiratory chain creates a proton gradient across the inner mitochondrial membrane, which couples respiration with oxidative phosphorylation and the preservation of energy in the chemical bonds of ATP. Akin to other mitochondrial enzymes, the respiratory chain is integrated into the inner mitochondrial membrane. The tight association with the mitochondrial phospholipid cardiolipin (CL) ensures its structural integrity and coordinates enzymatic activity. This review focuses on how changes in mitochondrial CL may be associated with heart failure. Dysfunctional CL has been found in diabetic cardiomyopathy, ischemia reperfusion injury and the aging heart. Barth syndrome (BTHS) is caused by an inherited defect in the biosynthesis of cardiolipin. Moreover, a dysfunctional CL pool causes other types of rare inherited cardiomyopathies, such as Sengers syndrome and Dilated Cardiomyopathy with Ataxia (DCMA). Here we review the impact of cardiolipin deficiency on mitochondrial functions in cellular and animal models. We describe the molecular mechanisms concerning mitochondrial dysfunction as an incitement of cardiomyopathy and discuss potential therapeutic strategies.
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16
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Bertero E, Kutschka I, Maack C, Dudek J. Cardiolipin remodeling in Barth syndrome and other hereditary cardiomyopathies. Biochim Biophys Acta Mol Basis Dis 2020; 1866:165803. [PMID: 32348916 DOI: 10.1016/j.bbadis.2020.165803] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 12/19/2019] [Accepted: 04/13/2020] [Indexed: 12/18/2022]
Abstract
Mitochondria play a prominent role in cardiac energy metabolism, and their function is critically dependent on the integrity of mitochondrial membranes. Disorders characterized by mitochondrial dysfunction are commonly associated with cardiac disease. The mitochondrial phospholipid cardiolipin directly interacts with a number of essential protein complexes in the mitochondrial membranes including the respiratory chain, mitochondrial metabolite carriers, and proteins critical for mitochondrial morphology. Barth syndrome is an X-linked disorder caused by an inherited defect in the biogenesis of the mitochondrial phospholipid cardiolipin. How cardiolipin deficiency impacts on mitochondrial function and how mitochondrial dysfunction causes cardiomyopathy has been intensively studied in cellular and animal models of Barth syndrome. These findings may also have implications for the molecular mechanisms underlying other inherited disorders associated with defects in cardiolipin, such as Sengers syndrome and dilated cardiomyopathy with ataxia (DCMA).
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Affiliation(s)
- Edoardo Bertero
- Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, 97078 Würzburg, Germany
| | - Ilona Kutschka
- Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, 97078 Würzburg, Germany
| | - Christoph Maack
- Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, 97078 Würzburg, Germany
| | - Jan Dudek
- Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, 97078 Würzburg, Germany.
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17
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Dard L, Blanchard W, Hubert C, Lacombe D, Rossignol R. Mitochondrial functions and rare diseases. Mol Aspects Med 2020; 71:100842. [PMID: 32029308 DOI: 10.1016/j.mam.2019.100842] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 12/26/2019] [Accepted: 12/27/2019] [Indexed: 12/19/2022]
Abstract
Mitochondria are dynamic cellular organelles responsible for a large variety of biochemical processes as energy transduction, REDOX signaling, the biosynthesis of hormones and vitamins, inflammation or cell death execution. Cell biology studies established that 1158 human genes encode proteins localized to mitochondria, as registered in MITOCARTA. Clinical studies showed that a large number of these mitochondrial proteins can be altered in expression and function through genetic, epigenetic or biochemical mechanisms including the interaction with environmental toxics or iatrogenic medicine. As a result, pathogenic mitochondrial genetic and functional defects participate to the onset and the progression of a growing number of rare diseases. In this review we provide an exhaustive survey of the biochemical, genetic and clinical studies that demonstrated the implication of mitochondrial dysfunction in human rare diseases. We discuss the striking diversity of the symptoms caused by mitochondrial dysfunction and the strategies proposed for mitochondrial therapy, including a survey of ongoing clinical trials.
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Affiliation(s)
- L Dard
- Bordeaux University, 33000, Bordeaux, France; INSERM U1211, 33000, Bordeaux, France; CELLOMET, CGFB-146 Rue Léo Saignat, Bordeaux, France
| | - W Blanchard
- Bordeaux University, 33000, Bordeaux, France; INSERM U1211, 33000, Bordeaux, France; CELLOMET, CGFB-146 Rue Léo Saignat, Bordeaux, France
| | - C Hubert
- Bordeaux University, 33000, Bordeaux, France; INSERM U1211, 33000, Bordeaux, France
| | - D Lacombe
- Bordeaux University, 33000, Bordeaux, France; INSERM U1211, 33000, Bordeaux, France; CHU de Bordeaux, Service de Génétique Médicale, F-33076, Bordeaux, France
| | - R Rossignol
- Bordeaux University, 33000, Bordeaux, France; INSERM U1211, 33000, Bordeaux, France; CELLOMET, CGFB-146 Rue Léo Saignat, Bordeaux, France.
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18
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Adenine Nucleotide Translocase 1 Expression is Coupled to the HSP27-Mediated TLR4 Signaling in Cardiomyocytes. Cells 2019; 8:cells8121588. [PMID: 31817787 PMCID: PMC6952976 DOI: 10.3390/cells8121588] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 12/03/2019] [Accepted: 12/03/2019] [Indexed: 12/21/2022] Open
Abstract
The cardiac-specific overexpression of the adenine nucleotide translocase 1 (ANT1) has cardioprotective effects in various experimental heart disease models. Here, we analyzed the link between ANT1 expression and heat shock protein 27 (HSP27)-mediated toll-like receptor 4 (TLR4) signaling, which represents a novel communication pathway between mitochondria and the extracellular environment. The interaction between ANT1 and HSP27 was identified by co-immunoprecipitation from neonatal rat cardiomyocytes. ANT1 transgenic (ANT1-TG) cardiomyocytes demonstrated elevated HSP27 expression levels. Increased levels of HSP27 were released from the ANT1-TG cardiomyocytes under both normoxic and hypoxic conditions. Extracellular HSP27 stimulated TLR4 signaling via protein kinase B (AKT). The HSP27-mediated activation of the TLR4 pathway was more pronounced in ANT1-TG cardiomyocytes than in wild-type (WT) cardiomyocytes. HSP27-specific antibodies inhibited TLR4 activation and the expression of HSP27. Inhibition of the HSP27-mediated TLR4 signaling pathway with the TLR4 inhibitor oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (OxPAPC) reduced the mitochondrial membrane potential (∆ψm) and increased caspase 3/7 activity, which are both markers for cell stress. Conversely, treating cardiomyocytes with recombinant HSP27 protein stimulated TLR4 signaling, induced HSP27 and ANT1 expression, and stabilized the mitochondrial membrane potential. The activation of HSP27 signaling was verified in ischemic ANT1-TG heart tissue, where it correlated with ANT1 expression and the tightness of the inner mitochondrial membrane. Our study shows a new mechanism by which ANT1 is part of the cardioprotective HSP27-mediated TLR4 signaling.
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Nicolas E, Tricarico R, Savage M, Golemis EA, Hall MJ. Disease-Associated Genetic Variation in Human Mitochondrial Protein Import. Am J Hum Genet 2019; 104:784-801. [PMID: 31051112 PMCID: PMC6506819 DOI: 10.1016/j.ajhg.2019.03.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 03/19/2019] [Indexed: 12/14/2022] Open
Abstract
Mitochondrial dysfunction has consequences not only for cellular energy output but also for cellular signaling pathways. Mitochondrial dysfunction, often based on inherited gene variants, plays a role in devastating human conditions such as mitochondrial neuropathies, myopathies, cardiovascular disorders, and Parkinson and Alzheimer diseases. Of the proteins essential for mitochondrial function, more than 98% are encoded in the cell nucleus, translated in the cytoplasm, sorted based on the presence of encoded mitochondrial targeting sequences (MTSs), and imported to specific mitochondrial sub-compartments based on the integrated activity of a series of mitochondrial translocases, proteinases, and chaperones. This import process is typically dynamic; as cellular homeostasis is coordinated through communication between the mitochondria and the nucleus, many of the adaptive responses to stress depend on modulation of mitochondrial import. We here describe an emerging class of disease-linked gene variants that are found to impact the mitochondrial import machinery itself or to affect the proteins during their import into mitochondria. As a whole, this class of rare defects highlights the importance of correct trafficking of mitochondrial proteins in the cell and the potential implications of failed targeting on metabolism and energy production. The existence of this variant class could have importance beyond rare neuromuscular disorders, given an increasing body of evidence suggesting that aberrant mitochondrial function may impact cancer risk and therapeutic response.
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Affiliation(s)
- Emmanuelle Nicolas
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Rossella Tricarico
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Michelle Savage
- Cancer Prevention and Control Program, Department of Clinical Genetics, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Erica A Golemis
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Michael J Hall
- Cancer Prevention and Control Program, Department of Clinical Genetics, Fox Chase Cancer Center, Philadelphia, PA 19111, USA.
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20
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Liu Y, Wang X, Coyne LP, Yang Y, Qi Y, Middleton FA, Chen XJ. Mitochondrial carrier protein overloading and misfolding induce aggresomes and proteostatic adaptations in the cytosol. Mol Biol Cell 2019; 30:1272-1284. [PMID: 30893019 PMCID: PMC6724602 DOI: 10.1091/mbc.e19-01-0046] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Previous studies in yeast showed that mitochondrial stressors not directly targeting the protein import machinery can cause mitochondrial precursor overaccumulation stress (mPOS) in the cytosol independent of bioenergetics. Here, we demonstrate mPOS and stress responses in human cells. We show that overloading of mitochondrial membrane carrier, but not matrix proteins, is sufficient to induce cytosolic aggresomes and apoptosis. The aggresomes appear to triage unimported mitochondrial proteins. Interestingly, expression of highly unstable mutant variants of the mitochondrial carrier protein, Ant1, also induces aggresomes despite a greater than 20-fold reduction in protein level compared to wild type. Thus, overloading of the protein import machinery, rather than protein accumulation, is critical for aggresome induction. The data suggest that the import of mitochondrial proteins is saturable and that the cytosol is limited in degrading unimported mitochondrial proteins. In addition, we found that EGR1, eEF1a, and ubiquitin C are up-regulated by Ant1 overloading. These proteins are known to promote autophagy, protein targeting to aggresomes, and the processing of protein aggregates, respectively. Finally, we found that overexpression of the misfolded variants of Ant1 induces additional cytosolic responses including proteasomal activation. In summary, our work captured a profound effect of unimported mitochondrial proteins on cytosolic proteostasis and revealed multiple anti-mPOS mechanisms in human cells.
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Affiliation(s)
- Yaxin Liu
- Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, NY 13210
| | - Xiaowen Wang
- Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, NY 13210
| | - Liam P Coyne
- Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, NY 13210
| | - Yuan Yang
- Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, NY 13210
| | - Yue Qi
- Department of Pathology, State University of New York Upstate Medical University, Syracuse, NY 13210
| | - Frank A Middleton
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, NY 13210
| | - Xin Jie Chen
- Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, NY 13210.,Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, NY 13210
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21
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Mitochondrial diseases caused by dysfunctional mitochondrial protein import. Biochem Soc Trans 2018; 46:1225-1238. [PMID: 30287509 DOI: 10.1042/bst20180239] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 08/20/2018] [Accepted: 08/31/2018] [Indexed: 12/18/2022]
Abstract
Mitochondria are essential organelles which perform complex and varied functions within eukaryotic cells. Maintenance of mitochondrial health and functionality is thus a key cellular priority and relies on the organelle's extensive proteome. The mitochondrial proteome is largely encoded by nuclear genes, and mitochondrial proteins must be sorted to the correct mitochondrial sub-compartment post-translationally. This essential process is carried out by multimeric and dynamic translocation and sorting machineries, which can be found in all four mitochondrial compartments. Interestingly, advances in the diagnosis of genetic disease have revealed that mutations in various components of the human import machinery can cause mitochondrial disease, a heterogenous and often severe collection of disorders associated with energy generation defects and a multisystem presentation often affecting the cardiovascular and nervous systems. Here, we review our current understanding of mitochondrial protein import systems in human cells and the molecular basis of mitochondrial diseases caused by defects in these pathways.
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22
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Dudek J, Hartmann M, Rehling P. The role of mitochondrial cardiolipin in heart function and its implication in cardiac disease. Biochim Biophys Acta Mol Basis Dis 2018; 1865:810-821. [PMID: 30837070 DOI: 10.1016/j.bbadis.2018.08.025] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 08/14/2018] [Accepted: 08/17/2018] [Indexed: 01/21/2023]
Abstract
Mitochondria play an essential role in the energy metabolism of the heart. Many of the essential functions are associated with mitochondrial membranes and oxidative phosphorylation driven by the respiratory chain. Mitochondrial membranes are unique in the cell as they contain the phospholipid cardiolipin. The important role of cardiolipin in cardiovascular health is highlighted by several cardiac diseases, in which cardiolipin plays a fundamental role. Barth syndrome, Sengers syndrome, and Dilated cardiomyopathy with ataxia (DCMA) are genetic disorders, which affect cardiolipin biosynthesis. Other cardiovascular diseases including ischemia/reperfusion injury and heart failure are also associated with changes in the cardiolipin pool. Here, we summarize molecular functions of cardiolipin in mitochondrial biogenesis and morphology. We highlight the role of cardiolipin for the respiratory chain, metabolite carriers, and mitochondrial metabolism and describe links to apoptosis and mitochondria specific autophagy (mitophagy) with possible implications in cardiac disease.
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Affiliation(s)
- Jan Dudek
- Institute of Cellular Biochemistry, University Medical Center Göttingen, D-37073 Göttingen, Germany
| | - Magnus Hartmann
- Institute of Cellular Biochemistry, University Medical Center Göttingen, D-37073 Göttingen, Germany
| | - Peter Rehling
- Institute of Cellular Biochemistry, University Medical Center Göttingen, D-37073 Göttingen, Germany; Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany.
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23
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Ogunbona OB, Baile MG, Claypool SM. Cardiomyopathy-associated mutation in the ADP/ATP carrier reveals translation-dependent regulation of cytochrome c oxidase activity. Mol Biol Cell 2018; 29:1449-1464. [PMID: 29688796 PMCID: PMC6014099 DOI: 10.1091/mbc.e17-12-0700] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 03/16/2018] [Accepted: 04/18/2018] [Indexed: 01/07/2023] Open
Abstract
How the absence of the major mitochondrial ADP/ATP carrier in yeast, Aac2p, results in a specific defect in cytochrome c oxidase (COX; complex IV) activity is a long-standing mystery. Aac2p physically associates with respiratory supercomplexes, which include complex IV, raising the possibility that its activity is dependent on its association with Aac2p. Here, we have leveraged a transport-dead pathogenic AAC2 point mutant to determine the basis for the reduced COX activity in the absence of Aac2p. The steady-state levels of complex IV subunits encoded by the mitochondrial genome are significantly reduced in the absence of Aac2p function, whether its association with respiratory supercomplexes is preserved or not. This diminution in COX amounts is not caused by a reduction in the mitochondrial genome copy number or the steady-state level of its transcripts, and does not reflect a defect in complex IV assembly. Instead, the absence of Aac2p activity, genetically or pharmacologically, results in an aberrant pattern of mitochondrial translation. Interestingly, compared with the complete absence of Aac2p, the complex IV-related defects are greater in mitochondria expressing the transport-inactive Aac2p mutant. Our results highlight a critical role for Aac2p transport in mitochondrial translation whose disturbance uniquely impacts cytochrome c oxidase.
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Affiliation(s)
- Oluwaseun B. Ogunbona
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205-2185
| | | | - Steven M. Claypool
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205-2185
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24
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Woznicka-Misaila A, Juillan-Binard C, Baud D, Pebay-Peyroula E, Ravaud S. Cell-free production, purification and characterization of human mitochondrial ADP/ATP carriers. Protein Expr Purif 2017; 144:46-54. [PMID: 29217202 DOI: 10.1016/j.pep.2017.11.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 11/17/2017] [Accepted: 11/29/2017] [Indexed: 11/17/2022]
Abstract
Mitochondrial Carriers (MCs) are responsible for fluent traffic of a variety of compounds that need to be shuttled via mitochondrial inner membranes to maintain cell metabolism. The ADP/ATP Carriers (AACs) are responsible for the import of ADP inside the mitochondria and the export of newly synthesized ATP. In human, four different AACs isoforms are described which are expressed in tissue-specific manner. They are involved in different genetic diseases and play a role in cancerogenesis. Up to now only the structures of the bovine (isoform 1) and yeast (isoforms 2 and 3) AAC have been determined in one particular conformation, obtained in complex with the CATR inhibitor. Herein, we report that full-length human ADP/ATP Carriers isoform 1 and 3 were successfully expressed in cell-free system and purified in milligram amounts in detergent-solubilized state. The proteins exhibited the expected secondary structure content. Thermostability profiles showing stabilization by the CATR inhibitor suggest that the carriers are well folded.
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Affiliation(s)
| | - Céline Juillan-Binard
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale (IBS), 38000 Grenoble, France
| | - Delphine Baud
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale (IBS), 38000 Grenoble, France
| | - Eva Pebay-Peyroula
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale (IBS), 38000 Grenoble, France
| | - Stéphanie Ravaud
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale (IBS), 38000 Grenoble, France.
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25
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Allali S, Dorboz I, Samaan S, Slama A, Rambaud C, Boespflug-Tanguy O, Sarret C. Mutation in the AGK gene in two siblings with unusual Sengers syndrome. Metab Brain Dis 2017; 32:2149-2154. [PMID: 28868593 DOI: 10.1007/s11011-017-0101-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Accepted: 08/21/2017] [Indexed: 12/14/2022]
Abstract
Sengers syndrome is a rare autosomal recessive metabolic disorder caused by lack of acylglycerol kinase due to mutations in the AGK gene. It is characterized by congenital cataract, hypertrophic cardiomyopathy, myopathy and lactic acidosis. Two clinical forms have been described: a severe neonatal form, and a more benign form displaying exercise intolerance. We describe two siblings with congenital cataract, cardiomyopathy, hypotonia, intellectual disability and lactic acidosis. Whole exome sequencing revealed a homozygous c.1035dup mutation in the two siblings, supporting a diagnosis of Sengers syndrome. Our patients presented an intermediate form with intellectual deficiency, an unusual feature in Sengers syndrome. This permitted a prenatal diagnosis for a following pregnancy.
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Affiliation(s)
- Sanae Allali
- Service des Urgences Pédiatriques, Hôpital Estaing, Centre Hospitalier Universitaire de Clermont-Ferrand, Clermont-Ferrand, France
| | - Imen Dorboz
- Inserm U1141 Paris Diderot Sorbonne Université-Paris Cité, DHU PROTECT, Hôpital Robert Debré, Paris, France
| | - Simon Samaan
- Département de Génétique, Hôpital Robert Debré, Assistance Publique - Hôpitaux de Paris, Paris, France
| | - Abdelhamid Slama
- pôle BPP-SP, Hôpital de Bicêtre, Assistance Publique - Hôpitaux de Paris, Le Kremlin-Bicêtre, France
| | - Charlène Rambaud
- Service de Génétique Médicale, Hôpital Estaing, Centre Hospitalier Universitaire de Clermont-Ferrand, Clermont-Ferrand, France
| | - Odile Boespflug-Tanguy
- Inserm U1141 Paris Diderot Sorbonne Université-Paris Cité, DHU PROTECT, Hôpital Robert Debré, Paris, France
| | - Catherine Sarret
- Service de Génétique Médicale, Hôpital Estaing, Centre Hospitalier Universitaire de Clermont-Ferrand, Clermont-Ferrand, France.
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26
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Vukotic M, Nolte H, König T, Saita S, Ananjew M, Krüger M, Tatsuta T, Langer T. Acylglycerol Kinase Mutated in Sengers Syndrome Is a Subunit of the TIM22 Protein Translocase in Mitochondria. Mol Cell 2017; 67:471-483.e7. [DOI: 10.1016/j.molcel.2017.06.013] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 05/13/2017] [Accepted: 06/13/2017] [Indexed: 11/15/2022]
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27
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Sengers Syndrome-Associated Mitochondrial Acylglycerol Kinase Is a Subunit of the Human TIM22 Protein Import Complex. Mol Cell 2017; 67:457-470.e5. [DOI: 10.1016/j.molcel.2017.06.014] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 05/28/2017] [Accepted: 06/13/2017] [Indexed: 11/19/2022]
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28
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Lu YW, Acoba MG, Selvaraju K, Huang TC, Nirujogi RS, Sathe G, Pandey A, Claypool SM. Human adenine nucleotide translocases physically and functionally interact with respirasomes. Mol Biol Cell 2017; 28:1489-1506. [PMID: 28404750 PMCID: PMC5449148 DOI: 10.1091/mbc.e17-03-0195] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 03/30/2017] [Accepted: 04/04/2017] [Indexed: 11/11/2022] Open
Abstract
A network of interactions for human adenine nucleotide translocases, required for oxidative phosphorylation, is reported. Of particular interest is an evolutionarily conserved and functionally important association with respiratory supercomplexes, which is surprising because the respirasomes of yeast and mammals are different. Members of the adenine nucleotide translocase (ANT) family exchange ADP for ATP across the mitochondrial inner membrane, an activity that is essential for oxidative phosphorylation (OXPHOS). Mutations in or dysregulation of ANTs is associated with progressive external ophthalmoplegia, cardiomyopathy, nonsyndromic intellectual disability, apoptosis, and the Warburg effect. Binding partners of human ANTs have not been systematically identified. The absence of such information has prevented a detailed molecular understanding of the assorted ANT-associated diseases, including insight into their disparate phenotypic manifestations. To fill this void, in this study, we define the interactomes of two human ANT isoforms. Analogous to its yeast counterpart, human ANTs associate with heterologous partner proteins, including the respiratory supercomplex (RSC) and other solute carriers. The evolutionarily conserved ANT–RSC association is particularly noteworthy because the composition, and thereby organization, of RSCs in yeast and human is different. Surprisingly, absence of the major ANT isoform only modestly impairs OXPHOS in HEK293 cells, indicating that the low levels of other isoforms provide functional redundancy. In contrast, pharmacological inhibition of OXPHOS expression and function inhibits ANT-dependent ADP/ATP exchange. Thus ANTs and the OXPHOS machinery physically interact and functionally cooperate to enhance ANT transport capacity and mitochondrial respiration.
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Affiliation(s)
- Ya-Wen Lu
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205-2185
| | - Michelle Grace Acoba
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205-2185
| | - Kandasamy Selvaraju
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205-2185
| | - Tai-Chung Huang
- McKusick-Nathans Institute of Genetic Medicine, Departments of Biological Chemistry, Pathology and Oncology, Johns Hopkins University School of Medicine, Baltimore, MD 21205-2185.,Department of Internal Medicine, National Taiwan University Hospital and National Taiwan University Cancer Center, Taipei 10051, Taiwan
| | - Raja S Nirujogi
- McKusick-Nathans Institute of Genetic Medicine, Departments of Biological Chemistry, Pathology and Oncology, Johns Hopkins University School of Medicine, Baltimore, MD 21205-2185
| | - Gajanan Sathe
- McKusick-Nathans Institute of Genetic Medicine, Departments of Biological Chemistry, Pathology and Oncology, Johns Hopkins University School of Medicine, Baltimore, MD 21205-2185
| | - Akhilesh Pandey
- McKusick-Nathans Institute of Genetic Medicine, Departments of Biological Chemistry, Pathology and Oncology, Johns Hopkins University School of Medicine, Baltimore, MD 21205-2185
| | - Steven M Claypool
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205-2185
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29
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El-Hattab AW, Craigen WJ, Scaglia F. Mitochondrial DNA maintenance defects. Biochim Biophys Acta Mol Basis Dis 2017; 1863:1539-1555. [PMID: 28215579 DOI: 10.1016/j.bbadis.2017.02.017] [Citation(s) in RCA: 185] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 01/31/2017] [Accepted: 02/14/2017] [Indexed: 01/12/2023]
Abstract
The maintenance of mitochondrial DNA (mtDNA) depends on a number of nuclear gene-encoded proteins including a battery of enzymes forming the replisome needed to synthesize mtDNA. These enzymes need to be in balanced quantities to function properly that is in part achieved by exchanging intramitochondrial contents through mitochondrial fusion. In addition, mtDNA synthesis requires a balanced supply of nucleotides that is achieved by nucleotide recycling inside the mitochondria and import from the cytosol. Mitochondrial DNA maintenance defects (MDMDs) are a group of diseases caused by pathogenic variants in the nuclear genes involved in mtDNA maintenance resulting in impaired mtDNA synthesis leading to quantitative (mtDNA depletion) and qualitative (multiple mtDNA deletions) defects in mtDNA. Defective mtDNA leads to organ dysfunction due to insufficient mtDNA-encoded protein synthesis, resulting in an inadequate energy production to meet the needs of affected organs. MDMDs are inherited as autosomal recessive or dominant traits, and are associated with a broad phenotypic spectrum ranging from mild adult-onset ophthalmoplegia to severe infantile fatal hepatic failure. To date, pathogenic variants in 20 nuclear genes known to be crucial for mtDNA maintenance have been linked to MDMDs, including genes encoding enzymes of mtDNA replication machinery (POLG, POLG2, TWNK, TFAM, RNASEH1, MGME1, and DNA2), genes encoding proteins that function in maintaining a balanced mitochondrial nucleotide pool (TK2, DGUOK, SUCLG1, SUCLA2, ABAT, RRM2B, TYMP, SLC25A4, AGK, and MPV17), and genes encoding proteins involved in mitochondrial fusion (OPA1, MFN2, and FBXL4).
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Affiliation(s)
- Ayman W El-Hattab
- Division of Clinical Genetics and Metabolic Disorders, Pediatrics Department, Tawam Hospital, Al-Ain, United Arab Emirates
| | - William J Craigen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.
| | - Fernando Scaglia
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
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Jiang H, Zhang C, Tang Y, Zhao J, Wang T, Liu H, Sun X. The regulator of calcineurin 1 increases adenine nucleotide translocator 1 and leads to mitochondrial dysfunctions. J Neurochem 2016; 140:307-319. [PMID: 27861892 PMCID: PMC5248620 DOI: 10.1111/jnc.13900] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 10/08/2016] [Accepted: 11/07/2016] [Indexed: 11/29/2022]
Abstract
The over‐expression of regulator of calcineurin 1 isoform 1 (RCAN1.1) has been implicated in mitochondrial dysfunctions of Alzheimer's disease; however, the mechanism linking RCAN1.1 over‐expression and the mitochondrial dysfunctions remains unknown. In this study, we use human neuroblastoma SH‐SY5Y cells stably expressing RCAN1.1S and rat primary neurons infected with RCAN1.1S expression lentivirus to study the association of RCAN1 with mitochondrial functions. Our study here showed that the over‐expression of RCAN1.1S remarkably up‐regulates the expression of adenine nucleotide translocator (ANT1) by stabilizing ANT1 mRNA. The increased ANT1 level leads to accelerated ATP–ADP exchange rate, more Ca2+‐induced mitochondrial permeability transition pore opening, increased cytochrome c release, and eventually cell apoptosis. Furthermore, knockdown of ANT1 expression brings these mitochondria perturbations caused by RCAN1.1S back to normal. The effect of RCAN1.1S on ANT1 was independent of its inhibition on calcineurin. This study elucidated a novel function of RCAN1 in mitochondria and provides a molecular basis for the RCAN1.1S over‐expression‐induced mitochondrial dysfunctions and neuronal apoptosis. ![]()
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Affiliation(s)
- Hui Jiang
- Otolaryngology Key Lab, Qilu Hospital of Shandong University, Jinan, Shandong, China.,Department of Pediatrics, 2nd Hospital of Shandong University, Jinan, Shandong, China
| | - Chen Zhang
- Otolaryngology Key Lab, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Yu Tang
- Otolaryngology Key Lab, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Juan Zhao
- Otolaryngology Key Lab, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Tan Wang
- Department of Geriatrics, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Heng Liu
- Otolaryngology Key Lab, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Xiulian Sun
- Brain Research Institute, Qilu Hospital of Shandong University, Jinan, Shandong, China
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Sengers syndrome: a unique cause of severe hypertrophic cardiomyopathy. J Electrocardiol 2015; 48:915-6. [DOI: 10.1016/j.jelectrocard.2015.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2015] [Indexed: 11/16/2022]
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Ahmed N, Ronchi D, Comi GP. Genes and Pathways Involved in Adult Onset Disorders Featuring Muscle Mitochondrial DNA Instability. Int J Mol Sci 2015; 16:18054-76. [PMID: 26251896 PMCID: PMC4581235 DOI: 10.3390/ijms160818054] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 07/27/2015] [Accepted: 07/28/2015] [Indexed: 12/31/2022] Open
Abstract
Replication and maintenance of mtDNA entirely relies on a set of proteins encoded by the nuclear genome, which include members of the core replicative machinery, proteins involved in the homeostasis of mitochondrial dNTPs pools or deputed to the control of mitochondrial dynamics and morphology. Mutations in their coding genes have been observed in familial and sporadic forms of pediatric and adult-onset clinical phenotypes featuring mtDNA instability. The list of defects involved in these disorders has recently expanded, including mutations in the exo-/endo-nuclease flap-processing proteins MGME1 and DNA2, supporting the notion that an enzymatic DNA repair system actively takes place in mitochondria. The results obtained in the last few years acknowledge the contribution of next-generation sequencing methods in the identification of new disease loci in small groups of patients and even single probands. Although heterogeneous, these genes can be conveniently classified according to the pathway to which they belong. The definition of the molecular and biochemical features of these pathways might be helpful for fundamental knowledge of these disorders, to accelerate genetic diagnosis of patients and the development of rational therapies. In this review, we discuss the molecular findings disclosed in adult patients with muscle pathology hallmarked by mtDNA instability.
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Affiliation(s)
- Naghia Ahmed
- Neurology Unit, IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, Dino Ferrari Centre, Department of Pathophysiology and Transplantation, Università degli Studi di Milano, via Francesco Sforza 35, Milan 20122, Italy.
| | - Dario Ronchi
- Neurology Unit, IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, Dino Ferrari Centre, Department of Pathophysiology and Transplantation, Università degli Studi di Milano, via Francesco Sforza 35, Milan 20122, Italy.
| | - Giacomo Pietro Comi
- Neurology Unit, IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, Dino Ferrari Centre, Department of Pathophysiology and Transplantation, Università degli Studi di Milano, via Francesco Sforza 35, Milan 20122, Italy.
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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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Kabunga P, Lau AK, Phan K, Puranik R, Liang C, Davis RL, Sue CM, Sy RW. Systematic review of cardiac electrical disease in Kearns–Sayre syndrome and mitochondrial cytopathy. Int J Cardiol 2015; 181:303-10. [DOI: 10.1016/j.ijcard.2014.12.038] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 12/06/2014] [Accepted: 12/12/2014] [Indexed: 11/27/2022]
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Mayr JA. Lipid metabolism in mitochondrial membranes. J Inherit Metab Dis 2015; 38:137-44. [PMID: 25082432 DOI: 10.1007/s10545-014-9748-x] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Revised: 07/10/2014] [Accepted: 07/15/2014] [Indexed: 12/26/2022]
Abstract
Mitochondrial membranes have a unique lipid composition necessary for proper shape and function of the organelle. Mitochondrial lipid metabolism involves biosynthesis of the phospholipids phosphatidylethanolamine, cardiolipin and phosphatidylglycerol, the latter is a precursor of the late endosomal lipid bis(monoacylglycero)phosphate. It also includes mitochondrial fatty acid synthesis necessary for the formation of the lipid cofactor lipoic acid. Furthermore the synthesis of coenzyme Q takes place in mitochondria as well as essential parts of the steroid and vitamin D metabolism. Lipid transport and remodelling, which are necessary for tailoring and maintaining specific membrane properties, are just partially unravelled. Mitochondrial lipids are involved in organelle maintenance, fission and fusion, mitophagy and cytochrome c-mediated apoptosis. Mutations in TAZ, SERAC1 and AGK affect mitochondrial phospholipid metabolism and cause Barth syndrome, MEGDEL and Sengers syndrome, respectively. In these disorders an abnormal mitochondrial energy metabolism was found, which seems to be due to disturbed protein-lipid interactions, affecting especially enzymes of the oxidative phosphorylation. Since a growing number of enzymes and transport processes are recognised as parts of the mitochondrial lipid metabolism, a further increase of lipid-related disorders can be expected.
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Affiliation(s)
- Johannes A Mayr
- Department of Paediatrics, Paracelsus Medical University Salzburg, Salzburg, 5020, Austria,
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Wortmann SB, Espeel M, Almeida L, Reimer A, Bosboom D, Roels F, de Brouwer APM, Wevers RA. Inborn errors of metabolism in the biosynthesis and remodelling of phospholipids. J Inherit Metab Dis 2015; 38:99-110. [PMID: 25178427 DOI: 10.1007/s10545-014-9759-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 07/29/2014] [Accepted: 07/31/2014] [Indexed: 11/24/2022]
Abstract
Since the proposal to define a separate subgroup of inborn errors of metabolism involved in the biosynthesis and remodelling of phospholipids, sphingolipids and long chain fatty acids in 2013, this group is rapidly expanding. This review focuses on the disorders involved in the biosynthesis of phospholipids. Phospholipids are involved in uncountable cellular processes, e.g. as structural components of membranes, by taking part in vesicle and mitochondrial fusion and fission or signal transduction. Here we provide an overview on both pathophysiology and the extremely heterogeneous clinical presentations of the disorders reported so far (Sengers syndrome (due to mutations in AGK), MEGDEL syndrome (or SERAC defect, SERAC1), Barth syndrome (or TAZ defect, TAZ), congenital muscular dystrophy due to CHKB deficiency (CHKB). Boucher-Neuhäuser/Gordon Holmes syndrome (PNPLA6), PHARC syndrome (ABHD12), hereditary spastic paraplegia type 28, 54 and 56 (HSP28, DDHD1; HSP54, DDHD2; HSP56, CYP2U1), Lenz Majewski syndrome (PTDSS1), spondylometaphyseal dysplasia with cone-rod dystrophy (PCYT1A), atypical haemolytic-uremic syndrome due to DGKE deficiency (DGKE).
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Affiliation(s)
- Saskia B Wortmann
- Nijmegen Centre for Mitochondrial Disorders (NCMD) at the Amalia Children's Hospital, Radboudumc, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands,
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Haghighi A, Haack TB, Atiq M, Mottaghi H, Haghighi-Kakhki H, Bashir RA, Ahting U, Feichtinger RG, Mayr JA, Rötig A, Lebre AS, Klopstock T, Dworschak A, Pulido N, Saeed MA, Saleh-Gohari N, Holzerova E, Chinnery PF, Taylor RW, Prokisch H. Sengers syndrome: six novel AGK mutations in seven new families and review of the phenotypic and mutational spectrum of 29 patients. Orphanet J Rare Dis 2014; 9:119. [PMID: 25208612 PMCID: PMC4167147 DOI: 10.1186/s13023-014-0119-3] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 07/17/2014] [Indexed: 01/28/2023] Open
Abstract
Background Sengers syndrome is an autosomal recessive condition characterized by congenital cataract, hypertrophic cardiomyopathy, skeletal myopathy and lactic acidosis. Mutations in the acylglycerol kinase (AGK) gene have been recently described as the cause of Sengers syndrome in nine families. Methods We investigated the clinical and molecular features of Sengers syndrome in seven new families; five families with the severe and two with the milder form. Results Sequence analysis of AGK revealed compound heterozygous or homozygous predicted loss-of-function mutations in all affected individuals. A total of eight different disease alleles were identified, of which six were novel, homozygous c.523_524delAT (p.Ile175Tyrfs*2), c.424-1G > A (splice site), c.409C > T (p.Arg137*) and c.877 + 3G > T (splice site), and compound heterozygous c.871C > T (p.Gln291*) and c.1035dup (p.Ile346Tyrfs*39). All patients displayed perinatal or early-onset cardiomyopathy and cataract, clinical features pathognomonic for Sengers syndrome. Other common findings included blood lactic acidosis and tachydyspnoea while nystagmus, eosinophilia and cervical meningocele were documented in only either one or two cases. Deficiency of the adenine nucleotide translocator was found in heart and skeletal muscle biopsies from two patients associated with respiratory chain complex I deficiency. In contrast to previous findings, mitochondrial DNA content was normal in both tissues. Conclusion We compare our findings to those in 21 previously reported AGK mutation-positive Sengers patients, confirming that Sengers syndrome is a clinically recognisable disorder of mitochondrial energy metabolism.
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Affiliation(s)
- Alireza Haghighi
- Department of Genetics, Harvard Medical School, 77 Ave Louis Pasteur, Boston 02115, MA, USA.
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Vartiainen S, Chen S, George J, Tuomela T, Luoto KR, O'Dell KMC, Jacobs HT. Phenotypic rescue of a Drosophila model of mitochondrial ANT1 disease. Dis Model Mech 2014; 7:635-48. [PMID: 24812436 PMCID: PMC4036471 DOI: 10.1242/dmm.016527] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
A point mutation in the Drosophila gene that codes for the major adult isoform of adenine nuclear translocase (ANT) represents a model for human diseases that are associated with ANT insufficiency [stress-sensitive B1 (sesB1)]. We characterized the organismal, bioenergetic and molecular phenotype of sesB1 flies then tested strategies to compensate the mutant phenotype. In addition to developmental delay and mechanical-stress-induced seizures, sesB1 flies have an impaired response to sound, defective male courtship, female sterility and curtailed lifespan. These phenotypes, excluding the latter two, are shared with the mitoribosomal protein S12 mutant, tko25t. Mitochondria from sesB1 adults showed a decreased respiratory control ratio and downregulation of cytochrome oxidase. sesB1 adults exhibited ATP depletion, lactate accumulation and changes in gene expression that were consistent with a metabolic shift towards glycolysis, characterized by activation of lactate dehydrogenase and anaplerotic pathways. Females also showed downregulation of many genes that are required for oogenesis, and their eggs, although fertilized, failed to develop to the larval stages. The sesB1 phenotypes of developmental delay and mechanical-stress-induced seizures were alleviated by an altered mitochondrial DNA background. Female sterility was substantially rescued by somatic expression of alternative oxidase (AOX) from the sea squirt Ciona intestinalis, whereas AOX did not alleviate developmental delay. Our findings illustrate the potential of different therapeutic strategies for ANT-linked diseases, based on alleviating metabolic stress.
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Affiliation(s)
- Suvi Vartiainen
- BioMediTech and Tampere University Hospital, FI-33014 University of Tampere, Finland
| | - Shanjun Chen
- BioMediTech and Tampere University Hospital, FI-33014 University of Tampere, Finland
| | - Jack George
- BioMediTech and Tampere University Hospital, FI-33014 University of Tampere, Finland
| | - Tea Tuomela
- BioMediTech and Tampere University Hospital, FI-33014 University of Tampere, Finland
| | - Kaisa R Luoto
- BioMediTech and Tampere University Hospital, FI-33014 University of Tampere, Finland
| | - Kevin M C O'Dell
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
| | - Howard T Jacobs
- BioMediTech and Tampere University Hospital, FI-33014 University of Tampere, Finland. Research Program of Molecular Neurology, FI-00014 University of Helsinki, Finland.
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Clémençon B, Babot M, Trézéguet V. The mitochondrial ADP/ATP carrier (SLC25 family): pathological implications of its dysfunction. Mol Aspects Med 2013; 34:485-93. [PMID: 23506884 DOI: 10.1016/j.mam.2012.05.006] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Accepted: 02/10/2012] [Indexed: 02/04/2023]
Abstract
In aerobic eukaryotic cells, the high energy metabolite ATP is generated mainly within the mitochondria following the process of oxidative phosphorylation. The mitochondrial ATP is exported to the cytoplasm using a specialized transport protein, the ADP/ATP carrier, to provide energy to the cell. Any deficiency or dysfunction of this membrane protein leads to serious consequences on cell metabolism and can cause various diseases such as muscular dystrophy. Described as a decisive player in the programmed cell death, it was recently shown to play a role in cancer. The objective of this review is to summarize the current knowledge of the involvement of the ADP/ATP carrier, encoded by the SLC25A4, SLC25A5, SLC25A6 and SLC25A31 genes, in human diseases and of the efforts made at designing different model systems to study this carrier and the associated pathologies through biochemical, genetic, and structural approaches.
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Affiliation(s)
- Benjamin Clémençon
- Institute of Biochemistry and Molecular Medicine, NCCR TransCure, University of Bern, Bern, Switzerland.
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Adenine nucleotide translocase, mitochondrial stress, and degenerative cell death. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2013; 2013:146860. [PMID: 23970947 PMCID: PMC3732615 DOI: 10.1155/2013/146860] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Revised: 06/14/2013] [Accepted: 06/24/2013] [Indexed: 12/18/2022]
Abstract
Mitochondria are intracellular organelles involved in ATP synthesis, apoptosis, calcium signaling, metabolism, and the synthesis of critical metabolic cofactors. Mitochondrial dysfunction is associated with age-related degenerative diseases. How mitochondrial dysfunction causes cell degeneration is not well understood. Recent studies have shown that mutations in the adenine nucleotide translocase (Ant) cause aging-dependent degenerative cell death (DCD) in yeast, which is sequentially manifested by inner membrane stress, mitochondrial DNA (mtDNA) loss, and progressive loss of cell viability. Ant is an abundant protein primarily involved in ADP/ATP exchange across the mitochondrial inner membrane. It also mediates basal proton leak and regulates the mitochondrial permeability transition pore. Missense mutations in the human Ant1 cause several degenerative diseases which are commonly manifested by fractional mtDNA deletions. Multiple models have been proposed to explain the Ant1-induced pathogenesis. Studies from yeast have suggested that in addition to altered nucleotide transport properties, the mutant proteins cause a global stress on the inner membrane. The mutant proteins likely interfere with general mitochondrial biogenesis in a dominant-negative manner, which secondarily destabilizes mtDNA. More recent work revealed that the Ant-induced DCD is suppressed by reduced cytosolic protein synthesis. This finding suggests a proteostatic crosstalk between mitochondria and the cytosol, which may play an important role for cell survival during aging.
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Bonofiglio D, Santoro A, Martello E, Vizza D, Rovito D, Cappello AR, Barone I, Giordano C, Panza S, Catalano S, Iacobazzi V, Dolce V, Andò S. Mechanisms of divergent effects of activated peroxisome proliferator-activated receptor-γ on mitochondrial citrate carrier expression in 3T3-L1 fibroblasts and mature adipocytes. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1831:1027-36. [PMID: 23370576 DOI: 10.1016/j.bbalip.2013.01.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Revised: 01/16/2013] [Accepted: 01/18/2013] [Indexed: 12/14/2022]
Abstract
The citrate carrier (CIC), a nuclear-encoded protein located in the mitochondrial inner membrane, plays an important metabolic role in the transport of acetyl-CoA from the mitochondrion to the cytosol in the form of citrate for fatty acid and cholesterol synthesis. Citrate has been reported to be essential for fibroblast differentiation into fat cells. Because peroxisome proliferator-activated receptor-gamma (PPARγ) is known to be one of the master regulators of adipogenesis, we aimed to study the regulation of CIC by the PPARγ ligand rosiglitazone (BRL) in 3T3-L1 fibroblasts and in adipocytes. We demonstrated that BRL up-regulated CIC mRNA and protein levels in fibroblasts, while it did not elicit any effects in mature adipocytes. The enhancement of CIC levels upon BRL treatment was reversed using the PPARγ antagonist GW9662, addressing how this effect was mediated by PPARγ. Functional experiments using a reporter gene containing rat CIC promoter showed that BRL enhanced CIC promoter activity. Mutagenesis studies, electrophoretic-mobility-shift assay and chromatin-immunoprecipitation analysis revealed that upon BRL treatment, PPARγ and Sp1 are recruited on the Sp1-containing region within the CIC promoter, leading to an increase in CIC expression. In addition, mithramycin, a specific inhibitor for Sp1-DNA binding activity, abolished the PPARγ-mediated up-regulation of CIC in fibroblasts. The stimulatory effects of BRL disappeared in mature adipocytes in which PPARγ/Sp1 complex recruited SMRT corepressor to the Sp1 site of the CIC promoter. Taken together, our results contribute to clarify the molecular mechanisms by which PPARγ regulates CIC expression during the differentiation stages of fibroblasts into mature adipocytes.
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Affiliation(s)
- Daniela Bonofiglio
- Dept. Pharmacy, Health Sciences and Nutritional, University of Calabria, Cosenza, Italy
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Siriwardena K, Mackay N, Levandovskiy V, Blaser S, Raiman J, Kantor PF, Ackerley C, Robinson BH, Schulze A, Cameron JM. Mitochondrial citrate synthase crystals: novel finding in Sengers syndrome caused by acylglycerol kinase (AGK) mutations. Mol Genet Metab 2013; 108:40-50. [PMID: 23266196 DOI: 10.1016/j.ymgme.2012.11.282] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Accepted: 11/24/2012] [Indexed: 11/16/2022]
Abstract
We report on two families with Sengers syndrome and mutations in the acylglycerol kinase gene (AGK). In the first family, two brothers presented with vascular strokes, lactic acidosis, cardiomyopathy and cataracts, abnormal muscle cell histopathology and mitochondrial function. One proband had very abnormal mitochondria with citrate synthase crystals visible in electron micrographs, associated with markedly high citrate synthase activity. Exome sequencing was used to identify mutations in the AGK gene in the index patient. Targeted sequencing confirmed the same homozygous mutation (c.3G>A, p.M1I) in the brother. The second family had four affected members, of which we examined two. They also presented with similar clinical symptoms, but no strokes. Postmortem heart and skeletal muscle tissues showed low complex I, III and IV activities in the heart, but normal in the muscle. Skin fibroblasts showed elevated lactate/pyruvate ratios and low complex I+III activity. Targeted sequencing led to identification of a homozygous c.979A>T, p.K327* mutation. AGK is located in the mitochondria and phosphorylates monoacylglycerol and diacylglycerol to lysophosphatidic acid and phosphatidic acid. Disruption of these signaling molecules affects the mitochondria's response to superoxide radicals, resulting in oxidative damage to mitochondrial DNA, lipids and proteins, and stimulation of cellular detoxification pathways. High levels of manganese superoxide dismutase protein were detected in all four affected individuals, consistent with increased free radical damage. Phosphatidic acid is also involved in the synthesis of phospholipids and its loss will result in changes to the lipid composition of the inner mitochondrial membrane. These effects manifest as cataract formation in the eye, respiratory chain dysfunction and cardiac hypertrophy in heart tissue. These two pedigrees confirm that mutation of AGK is responsible for the severe neonatal presentation of Sengers syndrome. The identification of citrate synthase precipitates by electron microscopy and the presence of vascular strokes in two siblings may expand the cellular and clinical phenotype of this disease.
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Affiliation(s)
- Komudi Siriwardena
- Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, Toronto, ON, Canada M5G 1X8
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Ravaud S, Bidon-Chanal A, Blesneac I, Machillot P, Juillan-Binard C, Dehez F, Chipot C, Pebay-Peyroula E. Impaired transport of nucleotides in a mitochondrial carrier explains severe human genetic diseases. ACS Chem Biol 2012; 7:1164-9. [PMID: 22497660 DOI: 10.1021/cb300012j] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The mitochondrial ADP/ATP carrier (AAC) is a prominent actor in the energetic regulation of the cell, importing ADP into the mitochondria and exporting ATP toward the cytoplasm. Severe genetic diseases have been ascribed to specific mutations in this membrane protein. How minute, well-localized modifications of the transporter impact the function of the mitochondria remains, however, largely unclear. Here, for the first time, the relationship between all documented pathological mutations of the AAC and its transport properties is established. Activity measurements combined synergistically with molecular-dynamics simulations demonstrate how all documented pathological mutations alter the binding affinity and the translocation kinetics of the nucleotides. Throwing a bridge between the pathologies and their molecular origins, these results reveal two distinct mechanisms responsible for AAC-related genetic disorders, wherein the mutations either modulate the association of the nucleotides to the carrier by modifying its electrostatic signature or reduce its conformational plasticity.
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Affiliation(s)
- Stéphanie Ravaud
- Université
Grenoble 1,
IBS, Institut de Biologie Structurale, 41, rue Jules Horowitz, 38027
Grenoble cedex 1, France
- CEA, IBS, Grenoble, France
- CNRS, IBS, Grenoble, France
| | - Axel Bidon-Chanal
- Nancy Université, BP239,
54506 Vandoeuvre-lès-Nancy Cedex, France
- CNRS, SRSMC, Nancy, France
| | - Iulia Blesneac
- Université
Grenoble 1,
IBS, Institut de Biologie Structurale, 41, rue Jules Horowitz, 38027
Grenoble cedex 1, France
- CEA, IBS, Grenoble, France
- CNRS, IBS, Grenoble, France
| | - Paul Machillot
- Université
Grenoble 1,
IBS, Institut de Biologie Structurale, 41, rue Jules Horowitz, 38027
Grenoble cedex 1, France
- CEA, IBS, Grenoble, France
- CNRS, IBS, Grenoble, France
| | - Céline Juillan-Binard
- Université
Grenoble 1,
IBS, Institut de Biologie Structurale, 41, rue Jules Horowitz, 38027
Grenoble cedex 1, France
- CEA, IBS, Grenoble, France
- CNRS, IBS, Grenoble, France
| | - François Dehez
- Nancy Université, BP239,
54506 Vandoeuvre-lès-Nancy Cedex, France
- CNRS, SRSMC, Nancy, France
| | - Chris Chipot
- Nancy Université, BP239,
54506 Vandoeuvre-lès-Nancy Cedex, France
- CNRS, SRSMC, Nancy, France
| | - Eva Pebay-Peyroula
- Université
Grenoble 1,
IBS, Institut de Biologie Structurale, 41, rue Jules Horowitz, 38027
Grenoble cedex 1, France
- CEA, IBS, Grenoble, France
- CNRS, IBS, Grenoble, France
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44
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Lack of the mitochondrial protein acylglycerol kinase causes Sengers syndrome. Am J Hum Genet 2012; 90:314-20. [PMID: 22284826 DOI: 10.1016/j.ajhg.2011.12.005] [Citation(s) in RCA: 157] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Revised: 12/02/2011] [Accepted: 12/08/2011] [Indexed: 11/23/2022] Open
Abstract
Exome sequencing of an individual with congenital cataracts, hypertrophic cardiomyopathy, skeletal myopathy, and lactic acidosis, all typical symptoms of Sengers syndrome, discovered two nonsense mutations in the gene encoding mitochondrial acylglycerol kinase (AGK). Mutation screening of AGK in further individuals with congenital cataracts and cardiomyopathy identified numerous loss-of-function mutations in an additional eight families, confirming the causal nature of AGK deficiency in Sengers syndrome. The loss of AGK led to a decrease of the adenine nucleotide translocator in the inner mitochondrial membrane in muscle, consistent with a role of AGK in driving the assembly of the translocator as a result of its effects on phospholipid metabolism in mitochondria.
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45
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Mayr JA, Zimmermann FA, Horváth R, Schneider HC, Schoser B, Holinski-Feder E, Czermin B, Freisinger P, Sperl W. Deficiency of the mitochondrial phosphate carrier presenting as myopathy and cardiomyopathy in a family with three affected children. Neuromuscul Disord 2011; 21:803-8. [PMID: 21763135 DOI: 10.1016/j.nmd.2011.06.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Revised: 05/12/2011] [Accepted: 06/10/2011] [Indexed: 01/12/2023]
Abstract
In a family three children presented with severe neonatal lactic acidosis, hypertrophic cardiomyopathy and generalised muscular hypotonia. One child died in infancy, two survived a clinically severe neonatal period. At an age of 9 and 17years, respectively, they present with exercise intolerance, proximal muscle weakness, non-progressive hypertrophic cardiomyopathy and normal mental development. In a muscle biopsy normal activity of respiratory chain enzymes was found; however the amount of the mitochondrial phosphate carrier was decreased. This protein is expressed in two tissue-specific isoforms generated by mutually exclusive alternative splicing of the SLC25A3 gene transcript. We identified a homozygous mutation c.158-9A>G located in the 5'-intron next to exon 3A specific for heart and skeletal muscle. This creates a novel splice site resulting in a more than 95% decrease of the wild type allele.
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Affiliation(s)
- Johannes A Mayr
- Department of Paediatrics, Paracelsus Medical University Salzburg, Müllner Hauptstrasse 48, Salzburg, Austria.
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46
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Nishi H, Ono K, Iwanaga Y, Horie T, Nagao K, Takemura G, Kinoshita M, Kuwabara Y, Mori RT, Hasegawa K, Kita T, Kimura T. MicroRNA-15b modulates cellular ATP levels and degenerates mitochondria via Arl2 in neonatal rat cardiac myocytes. J Biol Chem 2009; 285:4920-30. [PMID: 20007690 DOI: 10.1074/jbc.m109.082610] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
MicroRNAs (miRNAs or miRs) are small, non-coding RNAs that modulate mRNA stability and post-transcriptional translation. A growing body of evidence indicates that specific miRNAs can affect the cellular function of cardiomyocytes. In the present study, miRNAs that are highly expressed in the heart were overexpressed in neonatal rat ventricular myocytes, and cellular ATP levels were assessed. As a result, miR-15b, -16, -195, and -424, which have the same seed sequence, the most critical determinant of miRNA targeting, decreased cellular ATP levels. These results suggest that these miRNAs could specifically down-regulate the same target genes and consequently decrease cellular ATP levels. Through a bioinformatics approach, ADP-ribosylation factor-like 2 (Arl2) was identified as a potential target of miR-15b. It has already been shown that Arl2 localizes to adenine nucleotide transporter 1, the exchanger of ADP/ATP in mitochondria. Overexpression of miR-15b, -16, -195, and -424 suppressed the activity of a luciferase reporter construct fused with the 3'-untranslated region of Arl2. In addition, miR-15b overexpression decreased Arl2 mRNA and protein expression levels. The effects of Arl2 siRNA on cellular ATP levels were the same as those of miR-15b, and the expression of Arl2 could restore ATP levels reduced by miR-15b. A loss-of-function study of miR-15b resulted in increased Arl2 protein and cellular ATP levels. Electron microscopic analysis revealed that mitochondria became degenerated in cardiomyocytes that had been transduced with miR-15b and Arl2 siRNA. The present results suggest that miR-15b may decrease mitochondrial integrity by targeting Arl2 in the heart.
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Affiliation(s)
- Hitoo Nishi
- Department of Cardiovascular Medicine, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
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47
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Claypool SM. Cardiolipin, a critical determinant of mitochondrial carrier protein assembly and function. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:2059-68. [PMID: 19422785 DOI: 10.1016/j.bbamem.2009.04.020] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Revised: 03/31/2009] [Accepted: 04/28/2009] [Indexed: 10/20/2022]
Abstract
The ability of phospholipids to act as determinants of membrane protein structure and function is probably best exemplified by cardiolipin (CL), the signature phospholipid of mitochondria. Early efforts to reconstitute individual respiratory complexes and members of the mitochondrial carrier family, most notably the ADP/ATP carrier (AAC), often demonstrated the importance of CL. Over the past decade, the significance of CL in the organization of components of the electron transport chain into higher order assemblies, termed respiratory supercomplexes, has been established. Another protein required for oxidative phosphorylation, AAC, has received comparatively little attention likely stemming from the fact that AACs were thought to function in isolation as either homodimers or monomers. Recently however, AACs have been demonstrated to interact with the respiratory supercomplex, other members of the mitochondrial carrier family, and the TIM23 translocon. Interestingly, many if not all of these interactions depend on CL. As the paradigm for the mitochondrial carrier family, these discoveries with AAC suggest that other members of this large group of important proteins may be more gregarious than anticipated. Moreover, it is proposed that AAC and perhaps additional members of the mitochondrial carrier family might represent downstream targets of pathological states involving alterations in CL.
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Affiliation(s)
- Steven M Claypool
- Department of Physiology, Johns Hopkins Medical School, MD 21205, USA.
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48
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Trézéguet V, Pélosi L, Lauquin GJM, Brandolin G. The mitochondrial ADP/ATP carrier: functional and structural studies in the route of elucidating pathophysiological aspects. J Bioenerg Biomembr 2008; 40:435-43. [PMID: 18979193 DOI: 10.1007/s10863-008-9178-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2008] [Accepted: 07/23/2008] [Indexed: 01/21/2023]
Abstract
The mitochondrial ADP/ATP carrier plays a central role in aerobic cell energetics by providing to the cytosol the ATP generated by oxidative phosphorylation. Though discovered around 40 years ago owing to the existence of unique inhibitors and in spite of numerous experimental approaches, this carrier, which stands as a model of the mitochondrial solute carriers keeps some long-standing mystery. There are still open challenging questions among them the precise ADP/ATP transport mechanism, the functional oligomeric state of the carrier and relationships between human ADP/ATP carrier dysfunctioning and pathologies. Deciphering the 3D structure of this carrier afforded a considerable progress of the knowledge but requires now additional data focused on molecular dynamics from this static picture. State of the art in this topic is reviewed and debated in this paper in view of better comprehending origin of the discrepancies in these questions and, finally, the multiple physiological roles of this carrier in eukaryotic cell economy.
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Affiliation(s)
- Véronique Trézéguet
- Laboratoire de Physiologie Moléculaire et Cellulaire, Institut de Biochimie et Génétique Cellulaires-UMR 5095, CNRS-Université Bordeaux2, Bordeaux Cedex, France.
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49
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Farina F, Alberti A, Breuil N, Bolotin-Fukuhara M, Pinto M, Culetto E. Differential expression pattern of the four mitochondrial adenine nucleotide transporter ant genes and their roles during the development of Caenorhabditis elegans. Dev Dyn 2008; 237:1668-81. [PMID: 18498090 DOI: 10.1002/dvdy.21578] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The adenine nucleotide transporter (ANT) mediates exchange of cytosolic ADP and mitochondrial ATP. Although most species contain more than one ANT family member, it is not known whether their roles in developmental processes are redundant or specific. Here, we show that the Caenorhabditis elegans genome encodes four candidate ant genes (ant-1.1, ant-1.2, ant-1.3, and ant-1.4). We have investigated their spatiotemporal expression patterns and discovered that, whereas ANT-1.1 is a ubiquitously expressed mitochondrial protein, the other three ANT proteins show a restricted range of cell type expression. Moreover, only the disruption of ant-1.1 function, through RNA interference (RNAi), gives a mutant phenotype. Most of the ant-1.1(RNAi) mutant embryos arrest before the morphogenesis stage. Furthermore, ant-1.1 is also required postembryonically because RNAi mutants exhibit small size and life-span extension. Our results suggest that ant-1.1 is the only ant gene strictly required for embryonic and postembryonic development in C. elegans.
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Affiliation(s)
- Francesca Farina
- Université Paris-Sud 11, CNRS UMR8621, Institut de Génétique et Microbiologie, Orsay Cedex, France
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50
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Neuroradiologic findings in Sengers syndrome. Pediatr Neurol 2008; 39:113-5. [PMID: 18639755 DOI: 10.1016/j.pediatrneurol.2008.05.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2008] [Revised: 05/08/2008] [Accepted: 05/14/2008] [Indexed: 11/24/2022]
Abstract
Sengers syndrome is characterized by a constellation of congenital cataracts, hypertrophic cardiomyopathy, skeletal myopathy, and lactic acidosis. Two forms of the disease have been described: a fatal neonatal form, and a more benign form in which patients live into their second or third decades. With the exception of time to death, no findings have distinguished these two forms. We present 3 cases of neonatal Sengers syndrome with significant central nervous system involvement, a finding not previously described. We suggest that the fatal neonatal form of Sengers syndrome would be more accurately described as a mitochondrial encephalomyopathy. Cranial imaging may help distinguish the two types of this syndrome.
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