1
|
Tran DM, Tran TTT, Luong QH, Tran MTC. A preliminary retrospective evaluation of screening and diagnosis of ornithine transcarbamylase deficiency in high-risk patients at a referral center in Vietnam. Heliyon 2024; 10:e36003. [PMID: 39220945 PMCID: PMC11365392 DOI: 10.1016/j.heliyon.2024.e36003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 08/04/2024] [Accepted: 08/07/2024] [Indexed: 09/04/2024] Open
Abstract
Introduction To date, newborn screening (NBS) for proximal urea cycle disorders, including Ornithine transcarbamylase deficiency (OTCD), was not recommended due to the lack of appropriate tests and insufficient evidence of the benefits. This study aimed to investigate the potential of tandem mass spectrometry (MS/MS) for OTCD screening and its value in guiding further investigation to obtain a final diagnosis in high-risk patients. Methods The study included patients with OTCD referred to the National Children's Hospital between April 2020 and November 2023. A retrospective evaluation of amino acid concentrations measured by MS/MS and their ratios in patients with early-onset and late-onset OTCD was conducted. Results While all ten early-onset cases had glutamine concentrations above the upper limit, only five of them had citrulline concentrations below the lower limit of the reference interval. Only two late-onset cases had elevated glutamine levels, while all had citrulline within reference intervals. The Cit/Phe ratio was decreased, and the Gln/Cit and Met/Cit ratios were increased in all early-onset OTCD cases, while they were abnormal in only one late-onset case. Conclusions The preliminary results suggest that hyperglutaminemia, in combination with low or normal citrulline concentrations and specific ratios (Gln/Cit, Met/Cit, and Cit/Phe), can serve as reliable markers for screening early-onset OTCD in high-risk patients. However, these markers proved less sensitive for detecting the late-onset form, even in symptomatic patients.
Collapse
Affiliation(s)
| | | | | | - Mai Thi Chi Tran
- National Children's Hospital, Hanoi, Viet Nam
- Hanoi Medical University, Hanoi, Viet Nam
| |
Collapse
|
2
|
Sidorina A, Catesini G, Sacchetti E, Rizzo C, Dionisi-Vici C. Propionic Acidemia, Methylmalonic Acidemia, and Cobalamin C Deficiency: Comparison of Untargeted Metabolomic Profiles. Metabolites 2024; 14:428. [PMID: 39195524 DOI: 10.3390/metabo14080428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2024] [Revised: 07/12/2024] [Accepted: 07/31/2024] [Indexed: 08/29/2024] Open
Abstract
Methylmalonic acidemia (MMA), propionic acidemia (PA), and cobalamin C deficiency (cblC) share a defect in propionic acid metabolism. In addition, cblC is also involved in the process of homocysteine remethylation. These three diseases produce various phenotypes and complex downstream metabolic effects. In this study, we used an untargeted metabolomics approach to investigate the biochemical differences and the possible connections among the pathophysiology of each disease. The significantly changed metabolites in the untargeted urine metabolomic profiles of 21 patients (seven MMA, seven PA, seven cblC) were identified through statistical analysis (p < 0.05; log2FC > |1|) and then used for annotation. Annotated features were associated with different metabolic pathways potentially involved in the disease's development. Comparative statistics showed markedly different metabolomic profiles between MMA, PA, and cblC, highlighting the characteristic species for each disease. The most affected pathways were related to the metabolism of organic acids (all diseases), amino acids (all diseases), and glycine and its conjugates (in PA); the transsulfuration pathway; oxidative processes; and neurosteroid hormones (in cblC). The untargeted metabolomics study highlighted the presence of significant differences between the three diseases, pointing to the most relevant contrast in the cblC profile compared to MMA and PA. Some new biomarkers were proposed for PA, while novel data regarding the alterations of steroid hormone profiles and biomarkers of oxidative stress were obtained for cblC disease. The elevation of neurosteroids in cblC may indicate a potential connection with the development of ocular and neuronal deterioration.
Collapse
Affiliation(s)
- Anna Sidorina
- Division of Metabolic Diseases and Hepatology, Bambino Gesù Children's Hospital IRCCS, 00146 Rome, Italy
| | - Giulio Catesini
- Division of Metabolic Diseases and Hepatology, Bambino Gesù Children's Hospital IRCCS, 00146 Rome, Italy
| | - Elisa Sacchetti
- Division of Metabolic Diseases and Hepatology, Bambino Gesù Children's Hospital IRCCS, 00146 Rome, Italy
| | - Cristiano Rizzo
- Division of Metabolic Diseases and Hepatology, Bambino Gesù Children's Hospital IRCCS, 00146 Rome, Italy
| | - Carlo Dionisi-Vici
- Division of Metabolic Diseases and Hepatology, Bambino Gesù Children's Hospital IRCCS, 00146 Rome, Italy
| |
Collapse
|
3
|
Snyder MT, Manor J, Gijavanekar C, Mizerik E, Kralik SF, Elsea SH, Machol K, Emrick L, Scaglia F. Heteroplasmic pathogenic m.12315G>A variant in MT-TL2 presenting with MELAS syndrome and depletion of nitric oxide donors. Am J Med Genet A 2024; 194:e63461. [PMID: 37953071 DOI: 10.1002/ajmg.a.63461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 09/14/2023] [Accepted: 10/19/2023] [Indexed: 11/14/2023]
Abstract
The MT-TL2 m.12315G>A pathogenic variant has previously been reported in five individuals with mild clinical phenotypes. Herein we report the case of a 5-year-old child with heteroplasmy for this variant who developed neurological regression and stroke-like episodes similar to those observed in mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS). Biochemical evaluation revealed depletion of arginine on plasma amino acid analysis and low z-scores for citrulline on untargeted plasma metabolomics analysis. These findings suggested that decreased availability of nitric oxide may have contributed to the stroke-like episodes. The use of intravenous arginine during stroke-like episodes and daily enteral L-citrulline supplementation normalized her biochemical values of arginine and citrulline. Untargeted plasma metabolomics showed the absence of nicotinamide and 1-methylnicotinamide, and plasma total glutathione levels were low; thus, nicotinamide riboside and N-acetylcysteine therapies were initiated. This report expands the phenotype associated with the rare mitochondrial variant MT-TL2 m.12315G>A to include neurological regression and a MELAS-like phenotype. Individuals with this variant should undergo in-depth biochemical analysis to include untargeted plasma metabolomics, plasma amino acids, and glutathione levels to help guide a targeted approach to treatment.
Collapse
Affiliation(s)
- Matthew T Snyder
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Texas Children's Hospital, Houston, Texas, USA
| | - Joshua Manor
- Metabolic Diseases Unit, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Ramat Gan, Israel
| | - Charul Gijavanekar
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Elizabeth Mizerik
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Texas Children's Hospital, Houston, Texas, USA
| | - Stephen F Kralik
- Texas Children's Hospital, Houston, Texas, USA
- Department of Radiology, Baylor College of Medicine, Houston, Texas, USA
| | - Sarah H Elsea
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Keren Machol
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Texas Children's Hospital, Houston, Texas, USA
| | - Lisa Emrick
- Texas Children's Hospital, Houston, Texas, USA
- Department of Pediatrics, Division of Pediatric Neurology and Developmental Neuroscience, Baylor College of Medicine, Houston, Texas, USA
| | - Fernando Scaglia
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Texas Children's Hospital, Houston, Texas, USA
- Joint BCM-CUHK Center of Medical Genetics, Prince of Wales Hospital, Hong Kong SAR, China
| |
Collapse
|
4
|
Blood biomarkers for assessment of mitochondrial dysfunction: An expert review. Mitochondrion 2021; 62:187-204. [PMID: 34740866 DOI: 10.1016/j.mito.2021.10.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 09/28/2021] [Accepted: 10/28/2021] [Indexed: 12/20/2022]
Abstract
Although mitochondrial dysfunction is the known cause of primary mitochondrial disease, mitochondrial dysfunction is often difficult to measure and prove, especially when biopsies of affected tissue are not available. In order to identify blood biomarkers of mitochondrial dysfunction, we reviewed studies that measured blood biomarkers in genetically, clinically or biochemically confirmed primary mitochondrial disease patients. In this way, we were certain that there was an underlying mitochondrial dysfunction which could validate the biomarker. We found biomarkers of three classes: 1) functional markers measured in blood cells, 2) biochemical markers of serum/plasma and 3) DNA markers. While none of the reviewed single biomarkers may perfectly reveal all underlying mitochondrial dysfunction, combining biomarkers that cover different aspects of mitochondrial impairment probably is a good strategy. This biomarker panel may assist in the diagnosis of primary mitochondrial disease patients. As mitochondrial dysfunction may also play a significant role in the pathophysiology of multifactorial disorders such as Alzheimer's disease and glaucoma, the panel may serve to assess mitochondrial dysfunction in complex multifactorial diseases as well and enable selection of patients who could benefit from therapies targeting mitochondria.
Collapse
|
5
|
Almannai M, El-Hattab AW. Nitric Oxide Deficiency in Mitochondrial Disorders: The Utility of Arginine and Citrulline. Front Mol Neurosci 2021; 14:682780. [PMID: 34421535 PMCID: PMC8374159 DOI: 10.3389/fnmol.2021.682780] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 06/21/2021] [Indexed: 11/21/2022] Open
Abstract
Mitochondrial diseases represent a growing list of clinically heterogeneous disorders that are associated with dysfunctional mitochondria and multisystemic manifestations. In spite of a better understanding of the underlying pathophysiological basis of mitochondrial disorders, treatment options remain limited. Over the past two decades, there is growing evidence that patients with mitochondrial disorders have nitric oxide (NO) deficiency due to the limited availability of NO substrates, arginine and citrulline; decreased activity of nitric oxide synthase (NOS); and NO sequestration. Studies evaluating the use of arginine in patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) presenting with stroke-like episodes showed symptomatic improvement after acute administration as well as a reduction in the frequency and severity of stroke-like episodes following chronic use. Citrulline, another NO precursor, was shown through stable isotope studies to result in a greater increase in NO synthesis. Recent studies showed a positive response of arginine and citrulline in other mitochondrial disorders besides MELAS. Randomized-controlled studies with a larger number of patients are warranted to better understand the role of NO deficiency in mitochondrial disorders and the efficacy of NO precursors as treatment modalities in these disorders.
Collapse
Affiliation(s)
- Mohammed Almannai
- Section of Medical Genetics, Children's Hospital, King Fahad Medical City, Riyadh, Saudi Arabia.,College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Ayman W El-Hattab
- Department of Clinical Sciences, College of Medicine, University of Sharjah, Sharjah, United Arab Emirates.,Clinical Genetics, University Hospital Sharjah, Sharjah, United Arab Emirates
| |
Collapse
|
6
|
Prakash R, Kannan A. Mitochondrial DNA modification by CRISPR/Cas system: Challenges and future direction. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2021; 178:193-211. [PMID: 33685597 DOI: 10.1016/bs.pmbts.2020.12.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)/Cas (CRISPR associated endonuclease), a hotshot genome editing tool which is originally known to be the form of prokaryotic adaptive immune system against viral infections has gained all the attention of scientific community as a promising genome editing platform. This review encompasses a brief description of mitochondrial disease conditions associated with the alteration in mitochondrial genome (mtDNA) and highlights the key role of the CRISPR/Cas system pertaining to its working mechanism and its involvement in gene-based therapeutics in treating the foresaid mitochondrial diseases. Here, we also extend the perception related to the detailed mechanism of CRISPR/Cas system in mtDNA modification.
Collapse
Affiliation(s)
- Rajalakshmi Prakash
- Department of Protein Chemistry and Technology, CSIR-Central Food Technological Research Institute, Mysuru, India; Academy of Scientific and Innovative Research (AcSIR), CSIR-Central Food Technological Research Institute (CSIR-CFTRI) Campus, Mysuru, India
| | - Anbarasu Kannan
- Department of Protein Chemistry and Technology, CSIR-Central Food Technological Research Institute, Mysuru, India; Academy of Scientific and Innovative Research (AcSIR), CSIR-Central Food Technological Research Institute (CSIR-CFTRI) Campus, Mysuru, India.
| |
Collapse
|
7
|
Lee T, Yoshii K, Yoshida S, Suga T, Nakamura K, Sasai H, Murayama K, Kobayashi H, Hasegawa Y, Takeshima Y. Retrospective evaluations revealed pre-symptomatic citrulline concentrations measured by newborn screening were significantly low in late-onset ornithine transcarbamylase deficiency patients. Clin Chim Acta 2020; 510:633-637. [PMID: 32828733 DOI: 10.1016/j.cca.2020.08.027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 07/17/2020] [Accepted: 08/18/2020] [Indexed: 12/31/2022]
Abstract
INTRODUCTION Ornithine transcarbamylase deficiency (OTCD) is the most common urea cycle disorder. Late-onset OTCD manifests after the neonatal period; therefore, if pre-symptomatic diagnosis and treatment are performed, it can improve the prognosis by preventing hyperammonemia. However, pre-symptomatic diagnosis is unreliable as the specific screening marker of OTCD has not been established yet. This retrospective study aimed to evaluate the pre-symptomatic blood citrulline levels in patients with late-onset OTCD. METHODS Patients with late-onset OTCD who were born after the newborn screening based on tandem mass spectrometry (MS/MS-NBS) was started and were referred to Hyogo College of Medicine Hospital between 2014 and 2018 were included. Pre-symptomatic blood citrulline levels measured by MS/MS-NBS were retrospectively evaluated. RESULTS Four patients were included in this study. The pre-symptomatic blood citrulline levels were 2.02, 4.50, 4.97, and 3.75 µmol/l, respectively. Compared with the citrulline levels in all newborns in Hyogo prefecture, these values were significantly low. CONCLUSIONS These results suggest the possibility that hypocitrullinemia detected by the MS/MS-NBS can be used as a screening marker for some patients with late-onset OTCD. Further retrospective evaluation of pre-symptomatic citrulline levels in patients with late-onset OTCD, as well as prospective monitoring of hypocitrullinemia on the MS/MS-NBS should be conducted.
Collapse
Affiliation(s)
- Tomoko Lee
- Department of Pediatrics, Hyogo College of Medicine, Nishinomiya, Japan.
| | - Katsuhiko Yoshii
- Department of Pediatrics, Chibune General Hospital, Osaka, Japan
| | - Satoru Yoshida
- Department of Pediatrics, Seirei Mikatahara General Hospital, Hamamatsu, Japan
| | - Takenori Suga
- Pediatric Intensive Care Unit, Hyogo Prefectural Amagasaki General Medical Center, Amagasaki, Japan
| | - Kimitoshi Nakamura
- Department of Pediatrics, Kumamoto University Graduate School of Medicine, Kumamoto, Japan
| | - Hideo Sasai
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu, Japan
| | - Kei Murayama
- Department of Metabolism, Chiba Children's Hospital, Chiba, Japan
| | - Hironori Kobayashi
- Department of Pediatrics, Shimane University Faculty of Medicine, Shimane, Japan
| | - Yuki Hasegawa
- Department of Pediatrics, Shimane University Faculty of Medicine, Shimane, Japan
| | | |
Collapse
|
8
|
Al Jasmi F, Al Zaabi N, Al-Thihli K, Al Teneiji AM, Hertecant J, El-Hattab AW. Endothelial Dysfunction and the Effect of Arginine and Citrulline Supplementation in Children and Adolescents With Mitochondrial Diseases. J Cent Nerv Syst Dis 2020; 12:1179573520909377. [PMID: 32165851 PMCID: PMC7050027 DOI: 10.1177/1179573520909377] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 02/01/2020] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND In addition to the reduced energy production, characteristic of mitochondrial disorders, nitric oxide (NO) deficiency can occur as well. The NO produced by vascular endothelial cells relaxes vascular smooth muscles, resulting in vasodilation that maintains the patency of small blood vessels and promotes blood flow through microvasculature. Endothelial dysfunction due to inability of vascular endothelium to generate enough NO to maintain adequate vasodilation can result in decreased perfusion in the microvasculature of various tissues, contributing to many complications seen in individuals with mitochondrial diseases. The amino acids arginine and citrulline are NO precursors: increasing their concentrations could potentially restore NO production. METHODS In this study, we assessed endothelial dysfunction in children and adolescents with mitochondrial diseases. We also investigated the effect of arginine and citrulline supplementation on endothelial dysfunction in these individuals. We used peripheral arterial tonometry to measure the reactive hyperemic index (RHI), which is low when there is endothelial dysfunction. RESULTS The results demonstrated low RHI in individuals with mitochondrial diseases, indicating endothelial dysfunction. RHI increased with arginine or citrulline supplementation suggesting that supplementation with NO precursors can improve endothelial dysfunction by enhancing NO production. CONCLUSIONS This study is the first one to use peripheral arterial tonometry methodology in mitochondrial diseases. The results of this study provide evidence for endothelial dysfunction in mitochondrial diseases and demonstrate that arginine or citrulline supplementation can alleviate the endothelial dysfunction, providing more evidence for the potential therapeutic utility of these amino acids in mitochondrial diseases.
Collapse
Affiliation(s)
- Fatma Al Jasmi
- Division of Clinical Genetic and Metabolic Disorders, Tawam Hospital, Al-Ain, United Arab Emirates
- Department of Pediatrics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Nuha Al Zaabi
- Division of Clinical Genetic and Metabolic Disorders, Tawam Hospital, Al-Ain, United Arab Emirates
- Department of Pediatrics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Khalid Al-Thihli
- Genetic and Developmental Medicine Clinic, Sultan Qaboos University Hospital, Muscat, Oman
| | - Amal M Al Teneiji
- Genetic and Metabolic Division, Pediatrics Department, Sheikh Khalifa Medical City, Abu Dhabi, United Arab Emirates
| | - Jozef Hertecant
- Division of Clinical Genetic and Metabolic Disorders, Tawam Hospital, Al-Ain, United Arab Emirates
| | - Ayman W El-Hattab
- Department of Clinical Sciences, College of Medicine, University of Sharjah, Sharjah, United Arab Emirates
| |
Collapse
|
9
|
Staretz-Chacham O, Wormser O, Manor E, Birk OS, Ferreira CR. TMEM70 deficiency: Novel mutation and hypercitrullinemia during metabolic decompensation. Am J Med Genet A 2019; 179:1293-1298. [PMID: 30950220 PMCID: PMC10515609 DOI: 10.1002/ajmg.a.61138] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Revised: 02/06/2019] [Accepted: 03/09/2019] [Indexed: 09/24/2023]
Abstract
Respiratory chain disorders comprise a heterogeneous group of diseases that are the result of mutations in nuclear or mitochondrial genes. TMEM70 encodes a nuclear protein involved in the assembly of respiratory chain complex V. Although mutations in various genes can result in isolated complex V deficiency; TMEM70 mutations represent the most common reported etiology. TMEM70 deficiency is known to cause a syndrome of neonatal mitochondrial encephalocardiomyopathy, accompanied by elevated lactate and hyperammonemia. Elevated citrulline has been reported previously in different inborn errors of metabolism, although uncommonly associated with TMEMT70 deficiency. We present a series of two siblings diagnosed with TMEM70 deficiency, and describe hypercitrullinemia during decompensation as a new finding in this condition. The cause of hyperammonemia in TMEM70 deficiency was previously assumed to be related to carbamoyl phosphate synthase 1 deficiency, but our finding of hypercitrullinemia rules out this possibility. We thus propose a different etiology for the hyperammonemia seen in these patients.
Collapse
Affiliation(s)
- Orna Staretz-Chacham
- Metabolic Clinic, Pediatric Division, Soroka University Medical Center, Ben Gurion University, Beer Sheva, Israel
| | - Ohad Wormser
- The Morris Kahn Laboratory of Human Genetics, National Institute for Biotechnology in the Negev and Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva, Israel
- Shraga Segal Department of Microbiology, Immunology and Genetics, Ben Gurion University of the Negev, Beer Sheva, Israel
| | - Esther Manor
- Shraga Segal Department of Microbiology, Immunology and Genetics, Ben Gurion University of the Negev, Beer Sheva, Israel
- Genetics Institute, Soroka University Medical Center, Ben Gurion University of the Negev, Beer Sheva, Israel
| | - Ohad S Birk
- The Morris Kahn Laboratory of Human Genetics, National Institute for Biotechnology in the Negev and Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva, Israel
- Shraga Segal Department of Microbiology, Immunology and Genetics, Ben Gurion University of the Negev, Beer Sheva, Israel
- Genetics Institute, Soroka University Medical Center, Ben Gurion University of the Negev, Beer Sheva, Israel
| | - Carlos R Ferreira
- National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland
| |
Collapse
|
10
|
Clinical syndromes associated with mtDNA mutations: where we stand after 30 years. Essays Biochem 2018; 62:235-254. [DOI: 10.1042/ebc20170097] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 05/29/2018] [Accepted: 05/30/2018] [Indexed: 01/16/2023]
Abstract
The landmark year 1988 can be considered as the birthdate of mitochondrial medicine, when the first pathogenic mutations affecting mtDNA were associated with human diseases. Three decades later, the field still expands and we are not ‘scraping the bottom of the barrel’ yet. Despite the tremendous progress in terms of molecular characterization and genotype/phenotype correlations, for the vast majority of cases we still lack a deep understanding of the pathogenesis, good models to study, and effective therapeutic options. However, recent technological advances including somatic cell reprogramming to induced pluripotent stem cells (iPSCs), organoid technology, and tailored endonucleases provide unprecedented opportunities to fill these gaps, casting hope to soon cure the major primary mitochondrial phenotypes reviewed here. This group of rare diseases represents a key model for tackling the pathogenic mechanisms involving mitochondrial biology relevant to much more common disorders that affect our currently ageing population, such as diabetes and metabolic syndrome, neurodegenerative and inflammatory disorders, and cancer.
Collapse
|
11
|
Uittenbogaard M, Brantner CA, Fang Z, Wong LJC, Gropman A, Chiaramello A. Novel insights into the functional metabolic impact of an apparent de novo m.8993T>G variant in the MT-ATP6 gene associated with maternally inherited form of Leigh Syndrome. Mol Genet Metab 2018; 124:71-81. [PMID: 29602698 PMCID: PMC6016550 DOI: 10.1016/j.ymgme.2018.03.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 03/22/2018] [Accepted: 03/22/2018] [Indexed: 01/02/2023]
Abstract
In this study, we report a novel perpective of metabolic consequences for the m.8993T>G variant using fibroblasts from a proband with clinical symptoms compatible with Maternally Inherited Leigh Syndrome (MILS). Definitive diagnosis was corroborated by mitochondrial DNA testing for the pathogenic variant m.8993T>G in MT-ATP6 subunit by Sanger sequencing. The long-range PCR followed by massively parallel sequencing method detected the near homoplasmic m.8993T>G variant at 83% in the proband's fibroblasts and at 0.4% in the mother's fibroblasts. Our results are compatible with very low levels of germline heteroplasmy or an apparent de novo mutation. Our mitochondrial morphometric analysis reveals severe defects in mitochondrial cristae structure in the proband's fibroblasts. Our live-cell mitochondrial respiratory analyses show impaired oxidative phosphorylation with decreased spare respiratory capacity in response to energy stress in the proband's fibroblasts. We detected a diminished glycolysis with a lessened glycolytic capacity and reserve, revealing a stunted ability to switch to glycolysis upon full inhibition of OXPHOS activities. This dysregulated energy reprogramming results in a defective interplay between OXPHOS and glycolysis during an energy crisis. Our study sheds light on the potential pathophysiologic mechanism leading to chronic energy crisis in this MILS patient harboring the m.8993T>G variant.
Collapse
Affiliation(s)
- Martine Uittenbogaard
- Department of Anatomy and Regenerative Biology, George Washington University School of Medicine and Health Sciences, Washington, DC 20037, USA
| | - Christine A Brantner
- GW Nanofabrication and Imaging Center, Office of the Vice President for Research, George Washington University, Washington, DC 20052, USA
| | - ZiShui Fang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Lee-Jun C Wong
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Andrea Gropman
- Children's National Medical Center, Division of Neurogenetics and Developmental Pediatrics, Washington, DC 20010, USA
| | - Anne Chiaramello
- Department of Anatomy and Regenerative Biology, George Washington University School of Medicine and Health Sciences, Washington, DC 20037, USA.
| |
Collapse
|
12
|
Chen Q, Kirk K, Shurubor YI, Zhao D, Arreguin AJ, Shahi I, Valsecchi F, Primiano G, Calder EL, Carelli V, Denton TT, Beal MF, Gross SS, Manfredi G, D'Aurelio M. Rewiring of Glutamine Metabolism Is a Bioenergetic Adaptation of Human Cells with Mitochondrial DNA Mutations. Cell Metab 2018; 27:1007-1025.e5. [PMID: 29657030 PMCID: PMC5932217 DOI: 10.1016/j.cmet.2018.03.002] [Citation(s) in RCA: 119] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 01/03/2018] [Accepted: 03/12/2018] [Indexed: 01/05/2023]
Abstract
Using molecular, biochemical, and untargeted stable isotope tracing approaches, we identify a previously unappreciated glutamine-derived α-ketoglutarate (αKG) energy-generating anaplerotic flux to be critical in mitochondrial DNA (mtDNA) mutant cells that harbor human disease-associated oxidative phosphorylation defects. Stimulating this flux with αKG supplementation enables the survival of diverse mtDNA mutant cells under otherwise lethal obligatory oxidative conditions. Strikingly, we demonstrate that when residual mitochondrial respiration in mtDNA mutant cells exceeds 45% of control levels, αKG oxidative flux prevails over reductive carboxylation. Furthermore, in a mouse model of mitochondrial myopathy, we show that increased oxidative αKG flux in muscle arises from enhanced alanine synthesis and release into blood, concomitant with accelerated amino acid catabolism from protein breakdown. Importantly, in this mouse model of mitochondriopathy, muscle amino acid imbalance is normalized by αKG supplementation. Taken together, our findings provide a rationale for αKG supplementation as a therapeutic strategy for mitochondrial myopathies.
Collapse
Affiliation(s)
- Qiuying Chen
- Department of Pharmacology, Weill Cornell Medicine, New York, NY 10065, USA
| | - Kathryne Kirk
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA
| | - Yevgeniya I Shurubor
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA
| | - Dazhi Zhao
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA
| | - Andrea J Arreguin
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA
| | - Ifrah Shahi
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA
| | - Federica Valsecchi
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA
| | - Guido Primiano
- Institute of Neurology, Catholic University of the Sacred Heart, Rome, Italy
| | - Elizabeth L Calder
- Center for Stem Cell Biology and Developmental Biology Program, Sloan-Kettering Institute for Cancer Research, New York, NY 10065, USA
| | - Valerio Carelli
- IRCCS, Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy; Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | - Travis T Denton
- Department of Pharmaceutical Sciences, Washington State University, College of Pharmacy, Spokane, WA 99210, USA
| | - M Flint Beal
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA
| | - Steven S Gross
- Department of Pharmacology, Weill Cornell Medicine, New York, NY 10065, USA
| | - Giovanni Manfredi
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA.
| | - Marilena D'Aurelio
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA.
| |
Collapse
|
13
|
Lemoine S, Panaye M, Rabeyrin M, Errazuriz-Cerda E, Mousson de Camaret B, Petiot P, Juillard L, Guebre-Egziabher F. Renal Involvement in Neuropathy, Ataxia, Retinitis Pigmentosa (NARP) Syndrome: A Case Report. Am J Kidney Dis 2017; 71:754-757. [PMID: 29224958 DOI: 10.1053/j.ajkd.2017.09.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 09/22/2017] [Indexed: 11/11/2022]
Abstract
We report a case of a patient who had the mitochondrial cytopathy complex of neuropathy, ataxia, and retinitis pigmentosa (NARP) syndrome diagnosed at age 11 years with a biopsy-proven kidney involvement that progressed to end-stage renal disease at age 21 years. Mutations of mitochondrial DNA (mtDNA) are maternally inherited and lead to mitochondrial cytopathies with predominant neurologic manifestations: psychomotor retardation, epilepsy, ataxia, neuropathy, and myopathy. Given the ubiquitous nature of mitochondria, cellular dysfunction can also appear in tissues with high metabolic turnover; thus, there can be cardiac, digestive, ophthalmologic, and kidney complications. Mutations in the MT-ATP6 gene of mtDNA have been shown to cause NARP syndrome without renal involvement. We report a patient who had NARP syndrome diagnosed at age 11 years in whom glomerular proteinuria was present very early after diagnosis. Although neurologic manifestations were stable over time, he developed worsening proteinuria and kidney function. He started dialysis therapy at age 21 years. Kidney biopsy confirmed the mitochondrial cytopathy histologically, with abnormal mitochondria seen on electron microscopy. The MT-ATP6 gene mutation was detected in the kidney biopsy specimen.
Collapse
Affiliation(s)
- Sandrine Lemoine
- Hospices Civils de Lyon, Service de Néphrologie, Hôpital Edouard Herriot, Lyon, France; Université de Lyon, INSERM U1060, CarMeN, Université Lyon-1, Lyon, France
| | - Marine Panaye
- Hospices Civils de Lyon, Service de Néphrologie, Hôpital Edouard Herriot, Lyon, France
| | - Maud Rabeyrin
- Hospices Civils de Lyon, Laboratoire d'Anatomie et Cytologie Pathologique, Hôpital Edouard Herriot, Lyon, France
| | | | - Bénédicte Mousson de Camaret
- Hospices Civils de Lyon, Service des Maladies Héréditaires du Métabolisme, Centre de Biologie et de Pathologie Est, Bron, France
| | - Philippe Petiot
- Hospices Civils de Lyon, Explorations fonctionnelles Neurologiques, Centre de Référence des Maladies Neuro-Musculaires, Hôpital de la Croix-Rousse, Lyon, France
| | - Laurent Juillard
- Hospices Civils de Lyon, Service de Néphrologie, Hôpital Edouard Herriot, Lyon, France; Université de Lyon, INSERM U1060, CarMeN, Université Lyon-1, Lyon, France
| | - Fitsum Guebre-Egziabher
- Hospices Civils de Lyon, Service de Néphrologie, Hôpital Edouard Herriot, Lyon, France; Université de Lyon, INSERM U1060, CarMeN, Université Lyon-1, Lyon, France; Department of Nephrology Dialysis-Apheresis Transplantation, Centre hospitalier universitaire Grenoble Alpes, La Tronche, France.
| |
Collapse
|
14
|
Mordel P, Schaeffer S, Dupas Q, Laville MA, Gérard M, Chapon F, Allouche S. A 2 bp deletion in the mitochondrial ATP 6 gene responsible for the NARP (neuropathy, ataxia, and retinitis pigmentosa) syndrome. Biochem Biophys Res Commun 2017; 494:133-137. [PMID: 29054413 DOI: 10.1016/j.bbrc.2017.10.066] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Accepted: 10/13/2017] [Indexed: 01/12/2023]
Abstract
Mitochondrial (mt) DNA-associated NARP (neurogenic muscle weakness, ataxia, and retinitis pigmentosa) syndrome is due to mutation in the MT-ATP6 gene. We report the case of a 18-year-old man who presented with deafness, a myoclonic epilepsy, muscle weakness since the age of 10 and further developed a retinitis pigmentosa and ataxia. The whole mtDNA analysis by next-generation sequencing revealed the presence of the 2 bp microdeletion m.9127-9128 del AT in the ATP6 gene at 82% heteroplasmy in muscle and to a lower load in blood (10-20%) and fibroblasts (50%). Using the patient's fibroblasts, we demonstrated a 60% reduction of the oligomycin-sensitive ATPase hydrolytic activity, a 40% decrease in the ATP synthesis and determination of the mitochondrial membrane potential using the fluorescent probe tetramethylrhodamine, ethyl ester indicated a significant reduction in oligomycin sensitivity. In conclusion, we demonstrated that this novel AT deletion in the ATP6 gene is pathogenic and responsible for the NARP syndrome.
Collapse
Affiliation(s)
- Patrick Mordel
- Normandie Univ, UNICAEN, CHU Caen, Signalisation, électrophysiologie et imagerie des lésions d'ischémie-reperfusion myocardique, Caen, F-14032, France
| | | | - Quentin Dupas
- Normandie Univ, UNICAEN, CHU Caen, Signalisation, électrophysiologie et imagerie des lésions d'ischémie-reperfusion myocardique, Caen, F-14032, France
| | | | - Marion Gérard
- CHU de Caen, Department of medical genetics, Caen, F-14032, France
| | - Françoise Chapon
- CHU de Caen, Neuromuscular Competence Center, Caen, F-14032, France; CHU de Caen, Department of Pathology, Caen, F-14032, France
| | - S Allouche
- Normandie Univ, UNICAEN, CHU Caen, Signalisation, électrophysiologie et imagerie des lésions d'ischémie-reperfusion myocardique, Caen, F-14032, France; CHU de Caen, Department of biochemistry, Caen, F-14032, France.
| |
Collapse
|
15
|
Balasubramaniam S, Lewis B, Mock DM, Said HM, Tarailo-Graovac M, Mattman A, van Karnebeek CD, Thorburn DR, Rodenburg RJ, Christodoulou J. Leigh-Like Syndrome Due to Homoplasmic m.8993T>G Variant with Hypocitrullinemia and Unusual Biochemical Features Suggestive of Multiple Carboxylase Deficiency (MCD). JIMD Rep 2016; 33:99-107. [PMID: 27450367 DOI: 10.1007/8904_2016_559] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/01/2016] [Revised: 03/09/2016] [Accepted: 03/16/2016] [Indexed: 01/15/2023] Open
Abstract
Leigh syndrome (LS), or subacute necrotizing encephalomyelopathy, is a genetically heterogeneous, relentlessly progressive, devastating neurodegenerative disorder that usually presents in infancy or early childhood. A diagnosis of Leigh-like syndrome may be considered in individuals who do not fulfil the stringent diagnostic criteria but have features resembling Leigh syndrome.We describe a unique presentation of Leigh-like syndrome in a 3-year-old boy with elevated 3-hydroxyisovalerylcarnitine (C5-OH) on newborn screening (NBS). Subsequent persistent plasma elevations of C5-OH and propionylcarnitine (C3) as well as fluctuating urinary markers were suggestive of multiple carboxylase deficiency (MCD). Normal enzymology and mutational analysis of genes encoding holocarboxylase synthetase (HLCS) and biotinidase (BTD) excluded MCD. Biotin uptake studies were normal excluding biotin transporter deficiency. His clinical features at 13 months of age comprised psychomotor delay, central hypotonia, myopathy, failure to thrive, hypocitrullinemia, recurrent episodes of decompensation with metabolic keto-lactic acidosis and an episode of hyperammonemia. Biotin treatment from 13 months of age was associated with increased patient activity, alertness, and attainment of new developmental milestones, despite lack of biochemical improvements. Whole exome sequencing (WES) analysis failed to identify any other variants which could likely contribute to the observed phenotype, apart from the homoplasmic (100%) m.8993T>G variant initially detected by mitochondrial DNA (mtDNA) sequencing.Hypocitrullinemia has been reported in patients with the m.8993T>G variant and other mitochondrial disorders. However, persistent plasma elevations of C3 and C5-OH have previously only been reported in one other patient with this homoplasmic mutation. We suggest considering the m.8993T>G variant early in the diagnostic evaluation of MCD-like biochemical disturbances, particularly when associated with hypocitrullinemia on NBS and subsequent confirmatory tests. An oral biotin trial is also warranted.
Collapse
Affiliation(s)
- Shanti Balasubramaniam
- Metabolic Unit, Department of Rheumatology and Metabolic Medicine, Princess Margaret Hospital, Perth, WA, Australia. .,School of Paediatrics and Child Health, University of Western Australia, Perth, WA, Australia. .,Western Sydney Genetics Program, Children's Hospital at Westmead, Westmead, NSW, Australia.
| | - B Lewis
- PathWest Laboratories WA, Princess Margaret Hospital, Perth, WA, Australia
| | - D M Mock
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - H M Said
- Department of Medicine, University of California School of Medicine Irvine, Irvine, CA, USA
| | - M Tarailo-Graovac
- Centre for Molecular Medicine, Department of Medical Genetics, Child and Family Research Institute, University of British Columbia, Vancouver, BC, Canada
| | - A Mattman
- Adult Metabolic Diseases Clinic, Division of Endocrinology and Metabolism, Vancouver General Hospital, UBC, Vancouver, BC, Canada
| | - C D van Karnebeek
- Centre for Molecular Medicine, Department of Pediatrics, Child and Family Research Institute, University of British Columbia, Vancouver, BC, Canada
| | - D R Thorburn
- Murdoch Childrens Research Institute and Victorian Clinical Genetics Services, Royal Children's Hospital, Melbourne, VIC, Australia.,Department of Paediatrics, The University of Melbourne, Melbourne, VIC, Australia
| | - R J Rodenburg
- Radboud Center for Mitochondrial Medicine, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - J Christodoulou
- Murdoch Childrens Research Institute and Victorian Clinical Genetics Services, Royal Children's Hospital, Melbourne, VIC, Australia.,Department of Paediatrics, The University of Melbourne, Melbourne, VIC, Australia
| |
Collapse
|
16
|
Crippa BL, Leon E, Calhoun A, Lowichik A, Pasquali M, Longo N. Biochemical abnormalities in Pearson syndrome. Am J Med Genet A 2016; 167A:621-8. [PMID: 25691415 DOI: 10.1002/ajmg.a.36939] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 12/15/2014] [Indexed: 01/10/2023]
Abstract
Pearson marrow-pancreas syndrome is a multisystem mitochondrial disorder characterized by bone marrow failure and pancreatic insufficiency. Children who survive the severe bone marrow dysfunction in childhood develop Kearns-Sayre syndrome later in life. Here we report on four new cases with this condition and define their biochemical abnormalities. Three out of four patients presented with failure to thrive, with most of them having normal development and head size. All patients had evidence of bone marrow involvement that spontaneously improved in three out of four patients. Unique findings in our patients were acute pancreatitis (one out of four), renal Fanconi syndrome (present in all patients, but symptomatic only in one), and an unusual organic aciduria with 3-hydroxyisobutyric aciduria in one patient. Biochemical analysis indicated low levels of plasma citrulline and arginine, despite low-normal ammonia levels. Regression analysis indicated a significant correlation between each intermediate of the urea cycle and the next, except between ornithine and citrulline. This suggested that the reaction catalyzed by ornithine transcarbamylase (that converts ornithine to citrulline) might not be very efficient in patients with Pearson syndrome. In view of low-normal ammonia levels, we hypothesize that ammonia and carbamylphosphate could be diverted from the urea cycle to the synthesis of nucleotides in patients with Pearson syndrome and possibly other mitochondrial disorders.
Collapse
Affiliation(s)
- Beatrice Letizia Crippa
- Department of Pediatrics, Division of Medical Genetics, University of Utah, Salt Lake City, Utah; University of Milano, Milan, Italy
| | | | | | | | | | | |
Collapse
|
17
|
Mori M, Mytinger JR, Martin LC, Bartholomew D, Hickey S. m.8993T>G-Associated Leigh Syndrome with Hypocitrullinemia on Newborn Screening. JIMD Rep 2014; 17:47-51. [PMID: 25240982 DOI: 10.1007/8904_2014_332] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 06/09/2014] [Accepted: 07/01/2014] [Indexed: 12/31/2022] Open
Abstract
Citrulline is among the metabolites measured by expanded newborn screening (NBS). While hypocitrullinemia can be a marker for deficiency of proximal urea cycle enzymes such as ornithine transcarbamylase (OTC), only a handful of state newborn screening programs in the United States officially report a low citrulline value for further work-up due to low positive predictive value. We report a case of a male infant who was found to have hypocitrullinemia on NBS. After excluding proximal urea cycle disorders by DNA sequencing, his NBS result was felt to be a false positive. At 4 months of age, he developed poor feeding, failure to thrive, apnea and infantile spasms with a progression to intractable seizures, as well as persistent hypocitrullinemia. He was diagnosed with Leigh syndrome due to a maternally inherited homoplasmic m.8993T>G mutation in the ATPase 6 gene. His mother, who had previously been diagnosed with cerebral palsy, was concurrently diagnosed with neuropathy, ataxia, and retinitis pigmentosa (NARP) due to heteroplasmy of the same mutation. She had progressive muscle weakness, ataxia, and speech dyspraxia. The m.8993T>G mutation causes mitochondrial ATP synthase deficiency and it is hypothesized to undermine the synthesis of citrulline by CPS1. In addition to proximal urea cycle disorders, the evaluation of an infant with persistent hypocitrullinemia should include testing for the m.8993T>G mutation and other disorders that cause mitochondrial dysfunction.
Collapse
Affiliation(s)
- Mari Mori
- Section of Human and Molecular Genetics, Nationwide Children's Hospital, Columbus, OH, USA,
| | | | | | | | | |
Collapse
|
18
|
El-Hattab AW, Emrick LT, Chanprasert S, Craigen WJ, Scaglia F. Mitochondria: Role of citrulline and arginine supplementation in MELAS syndrome. Int J Biochem Cell Biol 2014; 48:85-91. [DOI: 10.1016/j.biocel.2013.12.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Revised: 11/14/2013] [Accepted: 12/26/2013] [Indexed: 12/18/2022]
|
19
|
El-Hattab AW, Emrick LT, Craigen WJ, Scaglia F. Citrulline and arginine utility in treating nitric oxide deficiency in mitochondrial disorders. Mol Genet Metab 2012; 107:247-52. [PMID: 22819233 DOI: 10.1016/j.ymgme.2012.06.018] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2012] [Revised: 06/30/2012] [Accepted: 06/30/2012] [Indexed: 12/20/2022]
Abstract
Mitochondrial diseases arise as a result of dysfunction of the respiratory chain, leading to inadequate ATP production required to meet the energy needs of various organs. On the other hand, nitric oxide (NO) deficiency can occur in mitochondrial diseases and potentially play major roles in the pathogenesis of several complications including stroke-like episodes, myopathy, diabetes, and lactic acidosis. NO deficiency in mitochondrial disorders can result from multiple factors including decreased NO production due to endothelial dysfunction, NO sequestration by cytochrome c oxidase, NO shunting into reactive nitrogen species formation, and decreased availability of the NO precursors arginine and citrulline. Arginine and citrulline supplementation can result in increased NO production and hence potentially have therapeutic effects on NO deficiency-related manifestations of mitochondrial diseases. Citrulline is a more efficient NO donor than arginine as it results in a greater increase in de novo arginine synthesis, which plays a major role in driving NO production. This concept is supported by the observation that the three enzymes responsible for recycling citrulline to NO (argininosuccinate synthase and lyase, and nitric oxide synthase) function as a complex that can result in compartmentalizing NO synthesis and channeling citrulline efficiently to NO synthesis. Clinical research evaluating the effect of arginine and citrulline in mitochondrial diseases is limited to uncontrolled open label studies demonstrating that arginine administration to subjects with MELAS syndrome results in improvement in the clinical symptoms associated with stroke-like episodes and a decrease in the frequency and severity of these episodes. Therefore, controlled clinical studies of the effects of arginine or citrulline supplementation on different aspects of mitochondrial diseases are needed to explore the potential therapeutic effects of these NO donors.
Collapse
Affiliation(s)
- Ayman W El-Hattab
- Medical Genetics Section, Department of Pediatrics, The Children's Hospital at King Fahad Medical City and King Saud bin Abdulaziz University for Health Science, Riyadh, Kingdom of Saudi Arabia
| | | | | | | |
Collapse
|
20
|
Leong DW, Komen JC, Hewitt CA, Arnaud E, McKenzie M, Phipson B, Bahlo M, Laskowski A, Kinkel SA, Davey GM, Heath WR, Voss AK, Zahedi RP, Pitt JJ, Chrast R, Sickmann A, Ryan MT, Smyth GK, Thorburn DR, Scott HS. Proteomic and metabolomic analyses of mitochondrial complex I-deficient mouse model generated by spontaneous B2 short interspersed nuclear element (SINE) insertion into NADH dehydrogenase (ubiquinone) Fe-S protein 4 (Ndufs4) gene. J Biol Chem 2012; 287:20652-63. [PMID: 22535952 PMCID: PMC3370248 DOI: 10.1074/jbc.m111.327601] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Revised: 04/05/2012] [Indexed: 01/11/2023] Open
Abstract
Eukaryotic cells generate energy in the form of ATP, through a network of mitochondrial complexes and electron carriers known as the oxidative phosphorylation system. In mammals, mitochondrial complex I (CI) is the largest component of this system, comprising 45 different subunits encoded by mitochondrial and nuclear DNA. Humans diagnosed with mutations in the gene NDUFS4, encoding a nuclear DNA-encoded subunit of CI (NADH dehydrogenase ubiquinone Fe-S protein 4), typically suffer from Leigh syndrome, a neurodegenerative disease with onset in infancy or early childhood. Mitochondria from NDUFS4 patients usually lack detectable NDUFS4 protein and show a CI stability/assembly defect. Here, we describe a recessive mouse phenotype caused by the insertion of a transposable element into Ndufs4, identified by a novel combined linkage and expression analysis. Designated Ndufs4(fky), the mutation leads to aberrant transcript splicing and absence of NDUFS4 protein in all tissues tested of homozygous mice. Physical and behavioral symptoms displayed by Ndufs4(fky/fky) mice include temporary fur loss, growth retardation, unsteady gait, and abnormal body posture when suspended by the tail. Analysis of CI in Ndufs4(fky/fky) mice using blue native PAGE revealed the presence of a faster migrating crippled complex. This crippled CI was shown to lack subunits of the "N assembly module", which contains the NADH binding site, but contained two assembly factors not present in intact CI. Metabolomic analysis of the blood by tandem mass spectrometry showed increased hydroxyacylcarnitine species, implying that the CI defect leads to an imbalanced NADH/NAD(+) ratio that inhibits mitochondrial fatty acid β-oxidation.
Collapse
Affiliation(s)
| | - Jasper C. Komen
- the Murdoch Childrens Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Parkville, Victoria 3052, Australia
| | | | - Estelle Arnaud
- the Département de Génétique Médicale, Université de Lausanne, 1005 Lausanne, Switzerland
| | - Matthew McKenzie
- the Centre for Reproduction and Development, Monash Institute of Medical Research, Clayton, Victoria 3168, Australia
| | - Belinda Phipson
- Bioinformatics Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
| | - Melanie Bahlo
- Bioinformatics Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
- Department of Mathematics and Statistics, University of Melbourne, Parkville, Victoria 3052, Australia
| | - Adrienne Laskowski
- the Murdoch Childrens Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Parkville, Victoria 3052, Australia
| | - Sarah A. Kinkel
- From the Molecular Medicine Division
- Immunology Division, and
- the Department of Medical Biology and
| | | | | | - Anne K. Voss
- From the Molecular Medicine Division
- the Department of Medical Biology and
| | - René P. Zahedi
- the Leibniz-Institut für Analytische Wissenschaften e.V., 44227 Dortmund, Germany
| | - James J. Pitt
- VCGS Pathology, Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, Victoria 3052, Australia
| | - Roman Chrast
- the Département de Génétique Médicale, Université de Lausanne, 1005 Lausanne, Switzerland
| | - Albert Sickmann
- the Leibniz-Institut für Analytische Wissenschaften e.V., 44227 Dortmund, Germany
- the Medizinisches Proteom Center, Ruhr-Universität-Bochum, 44780 Bochum, Germany
| | - Michael T. Ryan
- the Department of Biochemistry, La Trobe University, Bundoora, Victoria 3086, Australia, and
| | - Gordon K. Smyth
- Bioinformatics Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
- the Department of Medical Biology and
- Department of Mathematics and Statistics, University of Melbourne, Parkville, Victoria 3052, Australia
| | - David R. Thorburn
- the Murdoch Childrens Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Parkville, Victoria 3052, Australia
| | - Hamish S. Scott
- From the Molecular Medicine Division
- the Department of Medical Biology and
- the Department of Molecular Pathology, Centre for Cancer Biology, SA Pathology, Box 14 Rundle Mall Post Office, Adelaide, South Australia 5000, Australia, and
- the Schools of Medicine and Molecular and Biomedical Science, University of Adelaide, South Australia 5005, Australia
| |
Collapse
|
21
|
El-Hattab AW, Hsu JW, Emrick LT, Wong LJC, Craigen WJ, Jahoor F, Scaglia F. Restoration of impaired nitric oxide production in MELAS syndrome with citrulline and arginine supplementation. Mol Genet Metab 2012; 105:607-14. [PMID: 22325939 PMCID: PMC4093801 DOI: 10.1016/j.ymgme.2012.01.016] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 01/18/2012] [Accepted: 01/18/2012] [Indexed: 10/14/2022]
Abstract
Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome is one of the most common mitochondrial disorders. Although the pathogenesis of stroke-like episodes remains unclear, it has been suggested that mitochondrial proliferation may result in endothelial dysfunction and decreased nitric oxide (NO) availability leading to cerebral ischemic events. This study aimed to assess NO production in subjects with MELAS syndrome and the effect of the NO precursors arginine and citrulline. Using stable isotope infusion techniques, we assessed arginine, citrulline, and NO metabolism in control subjects and subjects with MELAS syndrome before and after arginine or citrulline supplementation. The results showed that subjects with MELAS had lower NO synthesis rate associated with reduced citrulline flux, de novo arginine synthesis rate, and plasma arginine and citrulline concentrations, and higher plasma asymmetric dimethylarginine (ADMA) concentration and arginine clearance. We conclude that the observed impaired NO production is due to multiple factors including elevated ADMA, higher arginine clearance, and, most importantly, decreased de novo arginine synthesis secondary to decreased citrulline availability. Arginine and, to a greater extent, citrulline supplementation increased the de novo arginine synthesis rate, the plasma concentrations and flux of arginine and citrulline, and NO production. De novo arginine synthesis increased markedly with citrulline supplementation, explaining the superior efficacy of citrulline in increasing NO production. The improvement in NO production with arginine or citrulline supplementation supports their use in MELAS and suggests that citrulline may have a better therapeutic effect than arginine. These findings can have a broader relevance for other disorders marked by perturbations in NO metabolism.
Collapse
Affiliation(s)
- Ayman W. El-Hattab
- Division of Medical Genetics, Department of Child Health, University of Missouri Health Care, One Hospital Drive, Columbia, MO, 65212, USA
| | - Jean W. Hsu
- US Department of Agriculture/Agricultural Research Service-Children’s Nutrition Research Center, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Lisa T. Emrick
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
- Texas Children’s Hospital, 6621 Fannin Street, Houston, TX 77030, USA
| | - Lee-Jun C. Wong
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - William J. Craigen
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
- Texas Children’s Hospital, 6621 Fannin Street, Houston, TX 77030, USA
| | - Farook Jahoor
- US Department of Agriculture/Agricultural Research Service-Children’s Nutrition Research Center, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
- Department of Pediatrics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Fernando Scaglia
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
- Texas Children’s Hospital, 6621 Fannin Street, Houston, TX 77030, USA
- Corresponding author at: Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, MS BCM225, Houston, TX, 77030, USA. Fax: +1 832 825 4294. (F. Scaglia)
| |
Collapse
|
22
|
Liu S, Lee YF, Chou S, Uno H, Li G, Brookes P, Massett MP, Wu Q, Chen LM, Chang C. Mice lacking TR4 nuclear receptor develop mitochondrial myopathy with deficiency in complex I. Mol Endocrinol 2011; 25:1301-10. [PMID: 21622535 DOI: 10.1210/me.2010-0455] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The estimated incidence of mitochondrial diseases in humans is approximately 1:5000 to 1:10,000, whereas the molecular mechanisms for more than 50% of human mitochondrial disease cases still remain unclear. Here we report that mice lacking testicular nuclear receptor 4 (TR4(-/-)) suffered mitochondrial myopathy, and histological examination of TR4(-/-) soleus muscle revealed abnormal mitochondrial accumulation. In addition, increased serum lactate levels, decreased mitochondrial ATP production, and decreased electron transport chain complex I activity were found in TR4(-/-) mice. Restoration of TR4 into TR4(-/-) myoblasts rescued mitochondrial ATP generation capacity and complex I activity. Further real-time PCR quantification and promoter studies found TR4 could modulate complex I activity via transcriptionally regulating the complex I assembly factor NDUFAF1, and restoration of NDUFAF1 level in TR4(-/-) myoblasts increased mitochondrial ATP generation capacity and complex I activity. Together, these results suggest that TR4 plays vital roles in mitochondrial function, which may help us to better understand the pathogenesis of mitochondrial myopathy, and targeting TR4 via its ligands/activators may allow us to develop better therapeutic approaches.
Collapse
Affiliation(s)
- Su Liu
- Department of Pathology, University of Rochester, Medical Center, Rochester, New York 14646, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Debray FG, Lambert M, Allard P, Mitchell GA. Low citrulline in Leigh disease: still a biomarker of maternally inherited Leigh syndrome. J Child Neurol 2010; 25:1000-2. [PMID: 20472868 DOI: 10.1177/0883073809351983] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Two siblings presented with encephalopathy, lactic acidosis, and hypocitrullinemia. Muscle and liver biopsies were considered for respiratory chain studies, but because of hypocitrullinemia, molecular analysis for maternally inherited Leigh syndrome was first performed, revealing in both siblings the mitochondrial DNA T8993G mutation (95% heteroplasmy), allowing to avoid tissue biopsies. Hypocitrullinemia, an occasional finding in mitochondrial diseases, has been specifically associated with T8993G mutation. However, only few patients have been reported, and the prevalence of hypocitrullinemia in 8993 mitochondrial DNA mutations is unknown. In a small series of 16 Leigh syndrome patients, sensitivity and specificity of hypocitrullinemia (< or = 12 micromol/L) for 8993 mitochondrial DNA mutations were 66% and 85%, respectively. Although studies in larger cohorts are necessary, we suggest considering T8993G mutation early in the diagnostic evaluation of infantile mitochondrial diseases with hypocitrullinemia, which minimizes the need for invasive procedures associated with a small but nonnegligible risk of complications and incorrect diagnosis.
Collapse
|
24
|
D'Aurelio M, Vives-Bauza C, Davidson MM, Manfredi G. Mitochondrial DNA background modifies the bioenergetics of NARP/MILS ATP6 mutant cells. Hum Mol Genet 2009; 19:374-86. [PMID: 19875463 DOI: 10.1093/hmg/ddp503] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Mutations in the mitochondrial DNA (mtDNA) encoded subunit 6 of ATPase (ATP6) are associated with variable disease expression, ranging from adult onset neuropathy, ataxia and retinitis pigmentosa (NARP) to fatal childhood maternally inherited Leigh's syndrome (MILS). Phenotypical variations have largely been attributed to mtDNA heteroplasmy. However, there is often a discrepancy between the levels of mutant mtDNA and disease severity. Therefore, the correlation among genetic defect, bioenergetic impairment and clinical outcome in NARP/MILS remains to be elucidated. We investigated the bioenergetics of cybrids from five patients carrying different ATP6 mutations: three harboring the T8993G, one with the T8993C and one with the T9176G mutation. The bioenergetic defects varied dramatically, not only among different ATP6 mutants, but also among lines carrying the same T8993G mutation. Mutants with the most severe ATP synthesis impairment showed defective respiration and disassembly of respiratory chain complexes. This indicates that respiratory chain defects modulate the bioenergetic impairment in NARP/MILS cells. Sequencing of the entire mtDNA from the different mutant cell lines identified variations in structural genes, resulting in amino acid changes that destabilize the respiratory chain. Taken together, these results indicate that the mtDNA background plays an important role in modulating the biochemical defects and clinical outcome in NARP/MILS.
Collapse
Affiliation(s)
- M D'Aurelio
- Weill Medical College of Cornell University, New York, NY 10065, USA
| | | | | | | |
Collapse
|
25
|
Morava E, Rodenburg RJ, Hol F, de Vries M, Janssen A, van den Heuvel L, Nijtmans L, Smeitink J. Clinical and biochemical characteristics in patients with a high mutant load of the mitochondrial T8993G/C mutations. Am J Med Genet A 2009; 140:863-8. [PMID: 16532470 DOI: 10.1002/ajmg.a.31194] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We retrospectively analyzed the clinical, histological, and biochemical data of 11 children, five of which carried the maternally-inherited mitochondrial T8993C and six carrying the T8993G point mutations in the ATP synthase 6 gene. The percentage of heteroplasmy was 95% or higher in muscle and in blood. All patients had an early clinical presentation with muscle hypotonia, severe extrapyramidal dysfunction and Leigh disease demonstrated by the cranial MRI. A slower clinical progression and more frequent sensory-neuronal involvement were noted in the patients carrying the T8993C mutation in a high mutation load in muscle and blood. No histological abnormality was found. In 9 out of 11 patients a decreased ATP production was detected, and complex V activity was deficient in all children. The activities of the respiratory enzyme complexes II and IV were normal, whereas an associated combined complex I and III deficiency were present in two patients. No obvious difference was found between the biochemical parameters of the two patient groups harboring different mutations in the same gene. No correlation was found between the degree of complex V enzyme deficiency and the severity of the phenotype. We confirmed an impaired assembly/stability of complex V in our patients. This is the first report of decreased activity and impaired assembly/stability of complex V in patients with T8993C mutations measured in muscle tissue.
Collapse
Affiliation(s)
- Eva Morava
- Department of Pediatrics, Radboud University Nijmegen Medical Centre, Nijmegen Centre for Mitochondrial Disorders, Nijmegen, The Netherlands.
| | | | | | | | | | | | | | | |
Collapse
|
26
|
Cavicchi C, Malvagia S, la Marca G, Gasperini S, Donati MA, Zammarchi E, Guerrini R, Morrone A, Pasquini E. Hypocitrullinemia in expanded newborn screening by LC-MS/MS is not a reliable marker for ornithine transcarbamylase deficiency. J Pharm Biomed Anal 2009; 49:1292-5. [PMID: 19359120 DOI: 10.1016/j.jpba.2009.03.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2009] [Revised: 03/02/2009] [Accepted: 03/03/2009] [Indexed: 12/14/2022]
Abstract
In an expanded newborn screening program for inborn errors of metabolism by LC-MS/MS in Tuscany, six newborns out of 169,000 showed decreased blood citrulline levels. In one of them, molecular analysis of the OTC gene identified the known p.Trp265Leu mutation, which is correlated with late-onset ornithine transcarbamylase deficiency (OTCD). Hypocitrullinemia is not a reliable marker for OTCD newborn screening, especially for late-onset forms that may exhibit normal citrulline levels. However, when hypocitrullinemia is detected in a newborn in whom intestinal dysfunction and prematurity have been excluded, OTCD should be investigated first because of the OTCD incidence (1:14,000) and the small size of the OTC gene coding sequence.
Collapse
Affiliation(s)
- C Cavicchi
- Metabolic and Muscular Unit, Clinic of Pediatric Neurology, AOU Meyer, Florence, Italy
| | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Inherited disorders affecting mitochondrial function are associated with glutathione deficiency and hypocitrullinemia. Proc Natl Acad Sci U S A 2009; 106:3941-5. [PMID: 19223582 DOI: 10.1073/pnas.0813409106] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Disorders affecting mitochondria, including those that directly affect the respiratory chain function or result from abnormalities in branched amino acid metabolism (organic acidemias), have been shown to be associated with impaired redox balance. Almost all of the evidence underlying this conclusion has been obtained from studies on patient biopsies or animal models. Since the glutathione (iGSH) system provides the main protection against oxidative damage, we hypothesized that untreated oxidative stress in individuals with mitochondrial dysfunction would result in chronic iGSH deficiency. We confirm this hypothesis here in studies using high-dimensional flow cytometry (Hi-D FACS) and biochemical analysis of freshly obtained blood samples from patients with mitochondrial disorders or organic acidemias. T lymphocyte subsets, monocytes and neutrophils from organic acidemia and mitochondrial patients who were not on antioxidant supplements showed low iGSH levels, whereas similar subjects on antioxidant supplements showed normal iGSH. Measures of iROS levels in blood were insufficient to reveal the chronic oxidative stress in untreated patients. Patients with organic acidemias showed elevated plasma protein carbonyls, while plasma samples from all patients tested showed hypocitrullinemia. These findings indicate that measurements of iGSH in leukocytes may be a particularly useful biomarker to detect redox imbalance in mitochondrial disorders and organic acidemias, thus providing a relatively non-invasive means to monitor disease status and response to therapies. Furthermore, studies here suggest that antioxidant therapy may be useful for relieving the chronic oxidative stress that otherwise occurs in patients with mitochondrial dysfunction.
Collapse
|
28
|
Schapira A. MITOCHONDRIAL DNA AND DISEASE. Continuum (Minneap Minn) 2008. [DOI: 10.1212/01.con.0000275629.24690.30] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|
29
|
Disorders of the mitochondrial respiratory chain. NEURODEGENER DIS 2005. [DOI: 10.1017/cbo9780511544873.063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
|
30
|
Naini A, Kaufmann P, Shanske S, Engelstad K, De Vivo DC, Schon EA. Hypocitrullinemia in patients with MELAS: an insight into the “MELAS paradox”. J Neurol Sci 2005; 229-230:187-93. [PMID: 15760638 DOI: 10.1016/j.jns.2004.11.026] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
L-citrulline, classified as a nonessential amino acid, is synthesized predominantly via Delta-1-pyrroline carboxylate synthase in the endothelial cells of the small intestine. In mammals, small quantities of citrulline are also produced in nitric oxide synthase-expressing cells. Considering the fact that the enzymes involved in the endogenous synthesis of L-citrulline are all located in the mitochondria and the fact that citrulline is a component of the citrulline-nitric oxide (NO) cycle, we hypothesized that the distinct clinical, biochemical, and morphological characteristics of MELAS, a maternally inherited mitochondrial disorder, might be due to alterations in nitric oxide homeostasis. Analysis of serum from MELAS patients showed that levels of plasma arginine were similar in both patients and in controls. However, levels of citrulline in MELAS patients were significantly lower than in controls, and there was a clear inverse correlation between arginine and citrulline levels in these patients. We found no correlation between the level of heteroplasmy and the plasma levels of either arginine or citrulline. We discuss the depressed citrulline levels in MELAS patients, who have an unusual and paradoxical pattern of vascular respiratory chain expression, in the context of NO homeostasis.
Collapse
Affiliation(s)
- Ali Naini
- Department of Neurology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA
| | | | | | | | | | | |
Collapse
|
31
|
Dubot A, Godinot C, Dumur V, Sablonnière B, Stojkovic T, Cuisset JM, Vojtiskova A, Pecina P, Jesina P, Houstek J. GUG is an efficient initiation codon to translate the human mitochondrial ATP6 gene. Biochem Biophys Res Commun 2004; 313:687-93. [PMID: 14697245 DOI: 10.1016/j.bbrc.2003.12.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A maternally inherited and practically homoplasmic mitochondrial (mtDNA) mutation, 8527A>G, changing the initiation codon AUG into GUG, normally coding for a valine, was observed in the ATP6 gene encoding the ATPase subunit a. No alternate Met codon could replace the normal translational initiator. The patient harboring this mutation exhibited clinical symptoms suggesting a mitochondrial disease but his mother who carried the same mtDNA mutation was healthy. The mutation was absent from 100 controls and occurred once amongst 44 patients suspected of Leber Hereditary Optic Neuropathy (LHON) but devoid of typical LHON mutations. In patient fibroblasts, no effect of 8527A>G mutation could be demonstrated on the biosynthesis of mtDNA-encoded proteins, on size and the content of ATPase subunit a, on ATP hydrolysis and on mitochondrial membrane potential. In addition, ATP synthesis was barely decreased. Therefore, GUG is a functional initiation codon for the human ATP6 gene.
Collapse
Affiliation(s)
- A Dubot
- Centre National de la Recherche Scientifique, Université Claude Bernard de Lyon I, 69622 Villeurbanne France
| | | | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Abstract
Mitochondrial disorders are important causes of progressive ataxia in children. Clinical examination, metabolic studies, imaging studies, muscle biopsies, and mitochondrial DNA studies are required to arrive at a specific diagnosis. There is poor correlation between phenotype and genotype in mitochondrial disorders. Ataxia is a major clinical presentation in Kearns-Sayre syndrome; mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes; myoclonic epilepsy with ragged-red fibers; neurogenic muscle weakness, ataxia, and retinitis pigmentosa; Leigh's syndrome; and coenzyme Q10 deficiency.
Collapse
|
33
|
Husson A, Brasse-Lagnel C, Fairand A, Renouf S, Lavoinne A. Argininosuccinate synthetase from the urea cycle to the citrulline-NO cycle. EUROPEAN JOURNAL OF BIOCHEMISTRY 2003; 270:1887-99. [PMID: 12709047 DOI: 10.1046/j.1432-1033.2003.03559.x] [Citation(s) in RCA: 224] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Argininosuccinate synthetase (ASS, EC 6.3.4.5) catalyses the condensation of citrulline and aspartate to form argininosuccinate, the immediate precursor of arginine. First identified in the liver as the limiting enzyme of the urea cycle, ASS is now recognized as a ubiquitous enzyme in mammalian tissues. Indeed, discovery of the citrulline-NO cycle has increased interest in this enzyme that was found to represent a potential limiting step in NO synthesis. Depending on arginine utilization, location and regulation of ASS are quite different. In the liver, where arginine is hydrolyzed to form urea and ornithine, the ASS gene is highly expressed, and hormones and nutrients constitute the major regulating factors: (a) glucocorticoids, glucagon and insulin, particularly, control the expression of this gene both during development and adult life; (b) dietary protein intake stimulates ASS gene expression, with a particular efficiency of specific amino acids like glutamine. In contrast, in NO-producing cells, where arginine is the direct substrate in the NO synthesis, ASS gene is expressed at a low level and in this way, proinflammatory signals constitute the main factors of regulation of the gene expression. In most cases, regulation of ASS gene expression is exerted at a transcriptional level, but molecular mechanisms are still poorly understood.
Collapse
Affiliation(s)
- Annie Husson
- ADEN, Institut Fédératif de Recherches Multidisciplinaires sur les Peptides no. 23 (IFRMP 23), Rouen, France.
| | | | | | | | | |
Collapse
|
34
|
Scaglia F, Scheuerle AE, Towbin JA, Armstrong DL, Sweetman L, Wong LJC. Neonatal presentation of ventricular tachycardia and a Reye-like syndrome episode associated with disturbed mitochondrial energy metabolism. BMC Pediatr 2002; 2:12. [PMID: 12507404 PMCID: PMC140035 DOI: 10.1186/1471-2431-2-12] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2002] [Accepted: 12/30/2002] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Hyperammonemia, hypoglycemia, hepatopathy, and ventricular tachycardia are common presenting features of carnitine-acylcarnitine translocase deficiency (Mendelian Inheritance in Man database: *212138), a mitochondrial fatty acid oxidation disorder with a lethal prognosis. These features have not been identified as the presenting features of mitochondrial cytopathy in the neonatal period. CASE PRESENTATION We describe an atypical presentation of mitochondrial cytopathy in a 2 day-old neonate. She presented with a Reye-like syndrome episode, premature ventricular contractions and ventricular tachycardia. Initial laboratory evaluation exhibited a large amount of 3-methylglutaconic acid on urine organic acid analysis, mild orotic aciduria and a nonspecific abnormal acylcarnitine profile. The evaluation for carnitine-acylcarnitine translocase deficiency and other fatty acid oxidation disorders was negative. The patient later developed a hypertrophic cardiomyopathy and continued to be affected by recurrent Reye-like syndrome episodes triggered by infections. A muscle biopsy exhibited signs of a mitochondrial cytopathy. During the course of her disease, her Reye-like syndrome episodes have subsided; however, cardiomyopathy has persisted along with fatigue and exercise intolerance. CONCLUSIONS This case illustrates that, in the neonatal period, hyperammonemia and ventricular tachycardia may be the presenting features of a lethal carnitine-acylcarnitine translocase deficiency or of a mitochondrial cytopathy, associated with a milder clinical course. This association broadens the spectrum of presenting phenotypes observed in patients with disturbed mitochondrial energy metabolism. Also, the presence of 3-methylglutaconic aciduria suggests mitochondrial dysfunction and mild orotic aciduria could potentially be used as a marker of mitochondrial disease.
Collapse
Affiliation(s)
- Fernando Scaglia
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Angela E Scheuerle
- Department of Genetics, Teratology and Ethics Consulting, Dallas, TX, USA
- Texas Birth Defects Research Center, Dallas, TX, USA
| | - Jeffrey A Towbin
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Dawna L Armstrong
- Department of Pathology, Baylor College of Medicine, Houston, TX, 77030, USA
| | | | - Lee-Jun C Wong
- Institute for Molecular and Human Genetics, Georgetown University Medical Center, Washington DC, 20007, USA
| |
Collapse
|
35
|
Schuelke M, Krude H, Finckh B, Mayatepek E, Janssen A, Schmelz M, Trefz F, Trijbels F, Smeitink J. Septo-optic dysplasia associated with a new mitochondrial cytochrome b mutation. Ann Neurol 2002; 51:388-92. [PMID: 11891837 DOI: 10.1002/ana.10151] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We report on a 25-year-old patient with isolated mitochondrial complex III deficiency and a new heteroplasmic mutation (T14849C) in the cytochrome b gene. He suffered from septo-optic dysplasia, retinitis pigmentosa, exercise intolerance, hypertrophic cardiomyopathy, and rhabdomyolysis. A HESX1 mutation was excluded as a cause of his septo-optic dysplasia. Low alpha-tocopherol concentrations in his muscles and an elevated urinary leukotriene E(4) excretion indicate increased production of reactive oxygen species.
Collapse
Affiliation(s)
- Markus Schuelke
- Department Neuropediatrics, Charité University Hospital, Berlin, Germany.
| | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Vilarinho L, Leão E, Barbot C, Santos M, Rocha H, Santorelli FM. Clinical and molecular studies in three Portuguese mtDNA T8993G families. Pediatr Neurol 2000; 22:29-32. [PMID: 10669202 DOI: 10.1016/s0887-8994(99)00113-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The T8993G mutation in the mitochondrial DNA adenosine triphosphatase 6 gene represents an important cause of maternally inherited Leigh's syndrome. Reported are the clinical findings and mutational loads in three Portuguese T8993G pedigrees. Polymerase chain reaction-restriction fragment length polymorphism analyses demonstrated the T8993G mutation in a high percentage of tissues from all patients (97% +/- 2.3%), but it was less abundant in the blood from 14 maternal relatives. The disease progressed severely in the probands but did not have the fatal course reported by others. To test whether this prolonged course was related to the presence of a specific, disease-associated haplogroup the origin of the mutational event in Portugal was traced. Haplotype investigation revealed an independent occurrence of the mutation in the three probands. These analyses represent the first molecular characterization of Portuguese patients with Leigh's syndrome.
Collapse
Affiliation(s)
- L Vilarinho
- Department of Clinical Biology, Instituto de Genética Médica, Porto, Portugal
| | | | | | | | | | | |
Collapse
|