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Del Greco C, Antonellis A. The Role of Nuclear-Encoded Mitochondrial tRNA Charging Enzymes in Human Inherited Disease. Genes (Basel) 2022; 13:genes13122319. [PMID: 36553587 PMCID: PMC9777667 DOI: 10.3390/genes13122319] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 11/30/2022] [Accepted: 12/02/2022] [Indexed: 12/13/2022] Open
Abstract
Aminoacyl-tRNA synthetases (ARSs) are highly conserved essential enzymes that charge tRNA with cognate amino acids-the first step of protein synthesis. Of the 37 nuclear-encoded human ARS genes, 17 encode enzymes are exclusively targeted to the mitochondria (mt-ARSs). Mutations in nuclear mt-ARS genes are associated with rare, recessive human diseases with a broad range of clinical phenotypes. While the hypothesized disease mechanism is a loss-of-function effect, there is significant clinical heterogeneity among patients that have mutations in different mt-ARS genes and also among patients that have mutations in the same mt-ARS gene. This observation suggests that additional factors are involved in disease etiology. In this review, we present our current understanding of diseases caused by mutations in the genes encoding mt-ARSs and propose explanations for the observed clinical heterogeneity.
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Affiliation(s)
- Christina Del Greco
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Anthony Antonellis
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
- Department of Neurology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
- Correspondence:
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2
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Göknar N, Keleşoğlu E, Kasap N, Üçkardeş D, Candan C. A case of chronic kidney disease with pulmonary hypertension, hyperuricemia, immunodeficiency and other extrarenal findings: Answers. Pediatr Nephrol 2022; 37:2617-2619. [PMID: 35445976 DOI: 10.1007/s00467-022-05560-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Revised: 03/16/2022] [Accepted: 03/16/2022] [Indexed: 11/24/2022]
Affiliation(s)
- Nilüfer Göknar
- Faculty of Medicine, Department of Pediatric Nephrology, Istanbul Medeniyet University, Istanbul, Turkey.
| | - Emre Keleşoğlu
- Faculty of Medicine, Department of Pediatric Nephrology, Istanbul Medeniyet University, Istanbul, Turkey
| | - Nurhan Kasap
- Faculty of Medicine, Department of Pediatric Allergy and Immunology, Istanbul Medeniyet University, Istanbul, Turkey
| | - Diana Üçkardeş
- Faculty of Medicine, Department of Pediatric Nephrology, Istanbul Medeniyet University, Istanbul, Turkey
| | - Cengiz Candan
- Faculty of Medicine, Department of Pediatric Nephrology, Istanbul Medeniyet University, Istanbul, Turkey
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3
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Ingelfinger JR. A new era for steroid-resistant nephrotic syndrome in childhood. Kidney Int 2022; 102:471-473. [PMID: 35988934 DOI: 10.1016/j.kint.2022.06.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 06/01/2022] [Indexed: 11/18/2022]
Abstract
Among youth with incident nephrotic syndrome, those with steroid-resistant nephrotic syndrome (SRNS) often have an ominous clinical course. Identifying them at or shortly after diagnosis would potentially prevent substantial morbidity and even mortality. For those with a specific monogenic form, targeted therapy might be possible, as is the case presently for CoQ10 insufficiency cases. Further, dissecting specific causes and pathways that lead to SRNS may lead to other targeted, potentially highly effective treatments.
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Affiliation(s)
- Julie R Ingelfinger
- Pediatric Nephrology and Hypertension Unit, MassGeneral Hospital for Children at Massachusetts General Hospital, Boston, Massachusetts, USA; Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA.
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4
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Xu C, Tong L, Rao J, Ye Q, Chen Y, Zhang Y, Xu J, Mao X, Meng F, Shen H, Lu Z, Cang X, Fu H, Wang S, Gu W, Lai EY, Guan M, Jiang P, Mao J. Heteroplasmic and homoplasmic m.616T>C in mitochondria tRNAPhe promote isolated chronic kidney disease and hyperuricemia. JCI Insight 2022; 7:157418. [PMID: 35472031 PMCID: PMC9220945 DOI: 10.1172/jci.insight.157418] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 04/22/2022] [Indexed: 11/22/2022] Open
Abstract
Inherited kidney diseases are the fifth most common cause of end-stage renal disease (ESRD). Mitochondrial dysfunction plays a vital role in the progression of inherited kidney diseases, while mitochondrial-transfer RNA (mt-tRNA) variants and their pathogenic contributions to kidney disease remain largely unclear. In this study, we identified the pathogenic mt-tRNAPhe 616T>C mutation in 3 families and documented that m.616T>C showed a high pathogenic threshold, with both heteroplasmy and homoplasmy leading to isolated chronic kidney disease and hyperuricemia without hematuria, proteinuria, or renal cyst formation. Moreover, 1 proband with homoplamic m.616T>C presented ESRD as a child. No symptoms of nervous system evolvement were observed in these families. Lymphoblast cells bearing m.616T>C exhibited swollen mitochondria, underwent active mitophagy, and showed respiratory deficiency, leading to reduced mitochondrial ATP production, diminished membrane potential, and overproduction of mitochondrial ROS. Pathogenic m.616T>C abolished a highly conserved base pair (A31-U39) in the anticodon stem-loop which altered the structure of mt-tRNAPhe, as confirmed by a decreased melting temperature and slower electrophoretic mobility of the mutant tRNA. Furthermore, the unstable structure of mt-tRNAPhe contributed to a shortage of steady-state mt-tRNAPhe and enhanced aminoacylation efficiency, which resulted in impaired mitochondrial RNA translation and a significant decrease in mtDNA–encoded polypeptides. Collectively, these findings provide potentially new insights into the pathogenesis underlying inherited kidney disease caused by mitochondrial variants.
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Affiliation(s)
- Chengxian Xu
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine and National Clinical Research Center for Child Health, Hangzhou, China
| | - Lingxiao Tong
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine and National Clinical Research Center for Child Health, Hangzhou, China
| | - Jia Rao
- Department of Nephrology, Children's Hospital of Fudan University, Shanghai, China
| | - Qing Ye
- Zhejiang Key Laboratory for Neonatal Diseases, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Yuxia Chen
- Department of Rehabilitation Medicine, Children's Hospital of Chongqing Medical University, Chongqing, China
| | - Yingying Zhang
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine and National Clinical Research Center for Child Health, Hangzhou, China
| | - Jie Xu
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine and National Clinical Research Center for Child Health, Hangzhou, China
| | - Xiaoting Mao
- Department of Human Genetics, Zhejiang University School of Medicine, Hangzhou, China
| | - Feilong Meng
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine and National Clinical Research Center for Child Health, Hangzhou, China
| | - Huijun Shen
- Department of Nephrology, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Zhihong Lu
- Department of Nephrology, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Xiaohui Cang
- Department of Human Genetics, Zhejiang University School of Medicine, Hangzhou, China
| | - Haidong Fu
- Department of Nephrology, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Shugang Wang
- Chigene (Beijing) Translational Medical Research Center, Chigene (Beijing) Translational Medical Research Center, Guangzhou, China
| | - Weiyue Gu
- Chigene (Beijing) Translational Medical Research Center, Chigene (Beijing) Translational Medical Research Center, Guangzhou, China
| | - En Yin Lai
- Department of Physiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Minxin Guan
- Department of Human Genetics, Zhejiang University School of Medicine, Hangzhou, China
| | - Pingping Jiang
- Department of Human Genetics, Zhejiang University School of Medicine, Hangzhou, China
| | - Jianhua Mao
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine and National Clinical Research Center for Child Health, Hangzhou, China
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5
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Clinicopathological Features of Mitochondrial Nephropathy. Kidney Int Rep 2022; 7:580-590. [PMID: 35257070 PMCID: PMC8897298 DOI: 10.1016/j.ekir.2021.12.028] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Revised: 12/16/2021] [Accepted: 12/20/2021] [Indexed: 12/12/2022] Open
Abstract
Introduction The clinicopathologic characteristics of nephropathy associated with mitochondrial disease (MD) remain unknown. We retrospectively analyzed a cohort of patients with proteinuria, decreased glomerular filtration rate, or Fanconi syndrome who had a genetic mutation confirmed as the cause of MD, defined as mitochondrial nephropathy. Methods This nationwide survey included 757 nephrology sections throughout Japan, and consequently, data on 81 cases of mitochondrial nephropathy were collected. Results The most common renal manifestation observed during the disease course was proteinuria. Hearing loss was the most common comorbidity; a renal-limited phenotype was observed only in mitochondrial DNA (mtDNA) point mutation and COQ8B mutation cases. We found a median time delay of 6.0 years from onset of renal manifestations to diagnosis. Focal segmental glomerular sclerosis (FSGS) was the most common pathologic diagnosis. We then focused on 63 cases with the m.3243A>G mutation. The rate of cases with diabetes was significantly higher among adult-onset cases than among childhood-onset cases. Pathologic diagnoses were more variable in adult-onset cases, including diabetic nephropathy, nephrosclerosis, tubulointerstitial nephropathy, and minor glomerular abnormalities. During the median observation period of 11.0 years from the first onset of renal manifestations in patients with m.3243A>G, renal replacement therapy (RRT) was initiated in 50.8% of patients. Death occurred in 25.4% of the patients during the median observation period of 12.0 years. The median estimated glomerular filtration rate (eGFR) decline was 5.4 ml/min per 1.73 m2/yr in the cases, especially 8.3 ml/min per 1.73 m2/yr in FSGS cases, with m.3243A>G. Conclusion Here, we described the clinicopathologic features and prognosis of mitochondrial nephropathy using large-scale data.
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6
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Galvan DL, Mise K, Danesh FR. Mitochondrial Regulation of Diabetic Kidney Disease. Front Med (Lausanne) 2021; 8:745279. [PMID: 34646847 PMCID: PMC8502854 DOI: 10.3389/fmed.2021.745279] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 08/30/2021] [Indexed: 12/14/2022] Open
Abstract
The role and nature of mitochondrial dysfunction in diabetic kidney disease (DKD) has been extensively studied. Yet, the molecular drivers of mitochondrial remodeling in DKD are poorly understood. Diabetic kidney cells exhibit a cascade of mitochondrial dysfunction ranging from changes in mitochondrial morphology to significant alterations in mitochondrial biogenesis, biosynthetic, bioenergetics and production of reactive oxygen species (ROS). How these changes individually or in aggregate contribute to progression of DKD remain to be fully elucidated. Nevertheless, because of the remarkable progress in our basic understanding of the role of mitochondrial biology and its dysfunction in DKD, there is great excitement on future targeted therapies based on improving mitochondrial function in DKD. This review will highlight the latest advances in understanding the nature of mitochondria dysfunction and its role in progression of DKD, and the development of mitochondrial targets that could be potentially used to prevent its progression.
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Affiliation(s)
- Daniel L Galvan
- Section of Nephrology, The University of Texas at MD Anderson Cancer Center, Houston, TX, United States
| | - Koki Mise
- Section of Nephrology, The University of Texas at MD Anderson Cancer Center, Houston, TX, United States.,Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Farhad R Danesh
- Section of Nephrology, The University of Texas at MD Anderson Cancer Center, Houston, TX, United States.,Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, TX, United States
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7
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Govers LP, Toka HR, Hariri A, Walsh SB, Bockenhauer D. Mitochondrial DNA mutations in renal disease: an overview. Pediatr Nephrol 2021; 36:9-17. [PMID: 31925537 PMCID: PMC7701126 DOI: 10.1007/s00467-019-04404-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 10/12/2019] [Accepted: 10/16/2019] [Indexed: 12/28/2022]
Abstract
Kidneys have a high energy demand to facilitate the reabsorption of the glomerular filtrate. For this reason, renal cells have a high density of mitochondria. Mitochondrial cytopathies can be the result of a mutation in both mitochondrial and nuclear DNA. Mitochondrial dysfunction can lead to a variety of renal manifestations. Examples of tubular manifestations are renal Fanconi Syndrome, which is often found in patients diagnosed with Kearns-Sayre and Pearson's marrow-pancreas syndrome, and distal tubulopathies, which result in electrolyte disturbances such as hypomagnesemia. Nephrotic syndrome can be a glomerular manifestation of mitochondrial dysfunction and is typically associated with focal segmental glomerular sclerosis on histology. Tubulointerstitial nephritis can also be seen in mitochondrial cytopathies and may lead to end-stage renal disease. The underlying mechanisms of these cytopathies remain incompletely understood; therefore, current therapies focus mainly on symptom relief. A better understanding of the molecular disease mechanisms is critical in order to improve treatments.
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Affiliation(s)
- Larissa P Govers
- Department of Renal Medicine, University College London, London, UK
| | - Hakan R Toka
- Manatee Kidney Diseases Consultants, Bradenton, USA
| | - Ali Hariri
- Clinical Development, Sanofi Rare Disease, Boston, USA
| | - Stephen B Walsh
- Department of Renal Medicine, University College London, London, UK
| | - Detlef Bockenhauer
- Department of Renal Medicine, University College London, London, UK.
- Renal Unit, Great Ormond Street Hospital for Children NHS Foundation Trust, Great Ormond Street, London, UK.
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8
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Kripps KA, Friederich MW, Chen T, Larson AA, Mirsky DM, Wang Y, Tanji K, Knight KM, Wong LJ, Van Hove JLK. A novel acceptor stem variant in mitochondrial tRNA Tyr impairs mitochondrial translation and is associated with a severe phenotype. Mol Genet Metab 2020; 131:398-404. [PMID: 33279411 PMCID: PMC7749820 DOI: 10.1016/j.ymgme.2020.11.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 11/13/2020] [Accepted: 11/13/2020] [Indexed: 11/25/2022]
Abstract
Genetic defects in mitochondrial DNA encoded tRNA genes impair mitochondrial translation with resultant defects in the mitochondrial respiratory chain and oxidative phosphorylation system. The phenotypic spectrum of disease seen in mitochondrial tRNA defects is variable and proving pathogenicity of new variants is challenging. Only three pathogenic variants have been described previously in the mitochondrial tRNATyr gene MT-TY, with the reported phenotypes consisting largely of adult onset myopathy and ptosis. We report a patient with a novel MT-TY acceptor stem variant m.5889A>G at high heteroplasmy in muscle, low in blood, and absent in the mother's blood. The phenotype consisted of a childhood-onset severe multi-system disorder characterized by a neurodegenerative course including ataxia and seizures, failure-to-thrive, combined myopathy and neuropathy, and hearing and vision loss. Brain imaging showed progressive atrophy and basal ganglia calcifications. Mitochondrial biomarkers lactate and GDF15 were increased. Functional studies showed a deficient activity of the respiratory chain enzyme complexes containing mtDNA-encoded subunits I, III and IV. There were decreased steady state levels of these mitochondrial complex proteins, and presence of incompletely assembled complex V forms in muscle. These changes are typical of a mitochondrial translational defect. These data support the pathogenicity of this novel variant. Careful review of variants in MT-TY additionally identified two other pathogenic variants, one likely pathogenic variant, nine variants of unknown significance, five likely benign and four benign variants.
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Affiliation(s)
- Kimberly A Kripps
- Section of Clinical Genetics and Metabolism, Department of Pediatrics, University of Colorado, Aurora, CO, USA
| | - Marisa W Friederich
- Section of Clinical Genetics and Metabolism, Department of Pediatrics, University of Colorado, Aurora, CO, USA; Department of Pathology and Laboratory Medicine, Children's Hospital Colorado, 13121 East 16th Avenue, Aurora, CO, USA
| | - Ting Chen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA; Department of Endocrinology, Genetics and Metabolism, Children's Hospital of Soochow University, Suzhou, China
| | - Austin A Larson
- Section of Clinical Genetics and Metabolism, Department of Pediatrics, University of Colorado, Aurora, CO, USA
| | - David M Mirsky
- Department of Radiology, University of Colorado, and Children's Hospital Colorado, Aurora, CO, USA
| | - Yue Wang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Kurenai Tanji
- Division of Neuropathology, Columbia University Medical Center, New York, NY, USA
| | - Kaz M Knight
- Section of Clinical Genetics and Metabolism, Department of Pediatrics, University of Colorado, Aurora, CO, USA
| | - Lee-Jun Wong
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Johan L K Van Hove
- Section of Clinical Genetics and Metabolism, Department of Pediatrics, University of Colorado, Aurora, CO, USA; Department of Pathology and Laboratory Medicine, Children's Hospital Colorado, 13121 East 16th Avenue, Aurora, CO, USA.
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9
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Schijvens AM, van de Kar NC, Bootsma-Robroeks CM, Cornelissen EA, van den Heuvel LP, Schreuder MF. Mitochondrial Disease and the Kidney With a Special Focus on CoQ 10 Deficiency. Kidney Int Rep 2020; 5:2146-2159. [PMID: 33305107 PMCID: PMC7710892 DOI: 10.1016/j.ekir.2020.09.044] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 09/29/2020] [Indexed: 12/13/2022] Open
Abstract
Mitochondrial cytopathies include a heterogeneous group of diseases that are characterized by impaired oxidative phosphorylation, leading to multi-organ involvement and progressive clinical deterioration. Most mitochondrial cytopathies that cause kidney symptoms are characterized by tubular defects, but glomerular, tubulointerstitial, and cystic diseases have also been described. Mitochondrial cytopathies can result from mitochondrial or nuclear DNA mutations. Early recognition of defects in the coenzyme Q10 (CoQ10) biosynthesis is important, as patients with primary CoQ10 deficiency may be responsive to treatment with oral CoQ10 supplementation, in contrast to most mitochondrial diseases. A literature search was conducted to investigate kidney involvement in genetic mitochondrial cytopathies and to identify mitochondrial and nuclear DNA mutations involved in mitochondrial kidney disease. Furthermore, we identified all reported cases to date with a CoQ10 deficiency with glomerular involvement, including 3 patients with variable renal phenotypes in our clinic. To date, 144 patients from 95 families with a primary CoQ10 deficiency and glomerular involvement have been described based on mutations in PDSS1, PDSS2, COQ2, COQ6, and COQ8B/ADCK4. This review provides an overview of kidney involvement in genetic mitochondrial cytopathies with a special focus on CoQ10 deficiency.
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Affiliation(s)
- Anne M. Schijvens
- Department of Pediatric Nephrology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Amalia Children’s Hospital, Nijmegen, the Netherlands
| | - Nicole C. van de Kar
- Department of Pediatric Nephrology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Amalia Children’s Hospital, Nijmegen, the Netherlands
| | - Charlotte M. Bootsma-Robroeks
- Department of Pediatric Nephrology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Amalia Children’s Hospital, Nijmegen, the Netherlands
| | - Elisabeth A. Cornelissen
- Department of Pediatric Nephrology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Amalia Children’s Hospital, Nijmegen, the Netherlands
| | - Lambertus P. van den Heuvel
- Department of Pediatric Nephrology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Amalia Children’s Hospital, Nijmegen, the Netherlands
- Department of Development and Regeneration,University Hospital Leuven, Leuven, Belgium
| | - Michiel F. Schreuder
- Department of Pediatric Nephrology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Amalia Children’s Hospital, Nijmegen, the Netherlands
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10
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Płoszaj T, Antosik K, Młudzik P, Traczyk-Borszyńska M, Borowiec M. Clinical use of NGS data from the targeted gene panel for mitochondrial diseases screening. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2020; 194:105529. [PMID: 32470904 DOI: 10.1016/j.cmpb.2020.105529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 04/09/2020] [Accepted: 05/01/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND AND OBJECTIVE Mitochondrial diseases are a frequent cause of inherited genetic disorders caused by mutations in both the mitochondrial and nuclear human genome. The new technique of high-throughput sequencing, which is used more and more frequently around the world, is most often focused on nuclear DNA. In some cases, such data after proper IT processing could also allow to determine alterations in mtDNA genome. In our work, we want to verify that off-target reads from targeted gene panels are sufficient data to determine pathogenic variants in the mitochondrial genome. METHODS We analyzed 50 patients who underwent routine diagnostics with the Illumina's TruSight One Sequencing Panel. In the entire bioinformatic analysis process, we have used only free, user-friendly and generally available online tools that do not require specialized IT knowledge. RESULTS Most of the data obtained were suitable for determining the presence of homoplasmic variants in mtDNA; 84% of the data met the minimum 20-fold coverage requirement as defined in the scientific literature for clinical data. We managed to identify 16 pathogenic variants in the examined genetic material (mtDNA) according to the ClinVar database. CONCLUSIONS In conclusion, we have outlined that off-target reads from targeted gene panel (TruSight One Sequencing Panel) may also be suitable for determining potentially pathogenic homoplasmic variants in mtDNA. We also described a simple pipeline based only on free tools available online. Introducing such a pipeline into a standard procedure of clinical units which carry out such research undoubtedly can extend the diagnostic potential by information about mtDNA, especially when it is based on purely free tools that do not require specialized bioinformatic knowledge.
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Affiliation(s)
- Tomasz Płoszaj
- Department of Clinical Genetics, Medical University of Lodz, Pomorska 251, 92-213 Lodz, Poland.
| | - Karolina Antosik
- Department of Clinical Genetics, Medical University of Lodz, Pomorska 251, 92-213 Lodz, Poland
| | - Paulina Młudzik
- Department of Clinical Genetics, Medical University of Lodz, Pomorska 251, 92-213 Lodz, Poland
| | | | - Maciej Borowiec
- Department of Clinical Genetics, Medical University of Lodz, Pomorska 251, 92-213 Lodz, Poland
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11
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Lim AZ, McMacken G, Rastelli F, Oláhová M, Baty K, Hopton S, Falkous G, Töpf A, Lochmüller H, Marini-Bettolo C, McFarland R, Taylor RW. A novel, pathogenic dinucleotide deletion in the mitochondrial MT-TY gene causing myasthenia-like features. Neuromuscul Disord 2020; 30:661-668. [PMID: 32684384 PMCID: PMC7477489 DOI: 10.1016/j.nmd.2020.06.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 06/16/2020] [Accepted: 06/17/2020] [Indexed: 11/29/2022]
Abstract
Mitochondrial DNA (mtDNA)-related diseases often pose a diagnostic challenge and require rigorous clinical and laboratory investigation. Pathogenic variants in the mitochondrial tRNA gene MT-TY, which encodes the tRNATyr, are a rare cause of mitochondrial disease. Here we describe a novel m.5860delTA anticodon variant in the MT-TY gene in a patient who initially presented with features akin to a childhood onset myasthenic syndrome. Using histochemical, immunohistochemical and protein studies we demonstrate that this mutation leads to severe biochemical defects of mitochondrial translation, which is reflected in the early onset and progressive phenotype. This case highlights the clinical overlap between mtDNA-related diseases and other neuromuscular disorders, and demonstrates the potential pitfalls in analysis of next generation sequencing results, given whole exome sequencing of a blood DNA sample failed to make a genetics diagnosis. Muscle biopsy remains an important requirement in the diagnosis of mitochondrial disease and in establishing the pathogenicity of novel mtDNA variants.
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Affiliation(s)
- Albert Z Lim
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Grace McMacken
- The John Walton Muscular Dystrophy Research Centre, Newcastle University, Newcastle upon Tyne, UK; Department of Neurosciences, Royal Victoria Hospital, Belfast Health and Social Care Trust, Belfast, UK
| | - Francesca Rastelli
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Monika Oláhová
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, Newcastle upon Tyne, UK; Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Karen Baty
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, Newcastle upon Tyne, UK; NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne, UK
| | - Sila Hopton
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, Newcastle upon Tyne, UK; NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne, UK
| | - Gavin Falkous
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, Newcastle upon Tyne, UK; NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne, UK
| | - Ana Töpf
- The John Walton Muscular Dystrophy Research Centre, Newcastle University, Newcastle upon Tyne, UK
| | - Hanns Lochmüller
- Department of Neuropediatrics and Muscle Disorders, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany; Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Spain; Research Institute, Children's Hospital of Eastern Ontario, Ottawa, Canada; Division of Neurology, Department of Medicine, Ottawa University, Ottawa, Canada
| | - Chiara Marini-Bettolo
- The John Walton Muscular Dystrophy Research Centre, Newcastle University, Newcastle upon Tyne, UK
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, Newcastle upon Tyne, UK; Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom.
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, Newcastle upon Tyne, UK; NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne, UK; Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
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12
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Ge M, Fontanesi F, Merscher S, Fornoni A. The Vicious Cycle of Renal Lipotoxicity and Mitochondrial Dysfunction. Front Physiol 2020; 11:732. [PMID: 32733268 PMCID: PMC7358947 DOI: 10.3389/fphys.2020.00732] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 06/08/2020] [Indexed: 12/15/2022] Open
Abstract
The kidney is one of the most energy-demanding organs that require abundant and healthy mitochondria to maintain proper function. Increasing evidence suggests a strong association between mitochondrial dysfunction and chronic kidney diseases (CKDs). Lipids are not only important sources of energy but also essential components of mitochondrial membrane structures. Dysregulation of mitochondrial oxidative metabolism and increased reactive oxygen species (ROS) production lead to compromised mitochondrial lipid utilization, resulting in lipid accumulation and renal lipotoxicity. However, lipotoxicity can be either the cause or the consequence of mitochondrial dysfunction. Imbalanced lipid metabolism, in turn, can hamper mitochondrial dynamics, contributing to the alteration of mitochondrial lipids and reduction in mitochondrial function. In this review, we summarize the interplay between renal lipotoxicity and mitochondrial dysfunction, with a focus on glomerular diseases.
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Affiliation(s)
- Mengyuan Ge
- Katz Family Division of Nephrology and Hypertension, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, United States.,Peggy and Harold Katz Family Drug Discovery Center, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Flavia Fontanesi
- Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Sandra Merscher
- Katz Family Division of Nephrology and Hypertension, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, United States.,Peggy and Harold Katz Family Drug Discovery Center, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Alessia Fornoni
- Katz Family Division of Nephrology and Hypertension, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, United States.,Peggy and Harold Katz Family Drug Discovery Center, University of Miami Miller School of Medicine, Miami, FL, United States
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13
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Park E, Lee C, Kim NKD, Ahn YH, Park YS, Lee JH, Kim SH, Cho MH, Cho H, Yoo KH, Shin JI, Kang HG, Ha IS, Park WY, Cheong HI. Genetic Study in Korean Pediatric Patients with Steroid-Resistant Nephrotic Syndrome or Focal Segmental Glomerulosclerosis. J Clin Med 2020; 9:jcm9062013. [PMID: 32604935 PMCID: PMC7355646 DOI: 10.3390/jcm9062013] [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: 06/05/2020] [Revised: 06/16/2020] [Accepted: 06/19/2020] [Indexed: 11/17/2022] Open
Abstract
Steroid-resistant nephrotic syndrome (SRNS) is one of the major causes of end-stage renal disease (ESRD) in childhood and is mostly associated with focal segmental glomerulosclerosis (FSGS). More than 50 monogenic causes of SRNS or FSGS have been identified. Recently, the mutation detection rate in pediatric patients with SRNS has been reported to be approximately 30%. In this study, genotype-phenotype correlations in a cohort of 291 Korean pediatric patients with SRNS/FSGS were analyzed. The overall mutation detection rate was 43.6% (127 of 291 patients). WT1 was the most common causative gene (23.6%), followed by COQ6 (8.7%), NPHS1 (8.7%), NUP107 (7.1%), and COQ8B (6.3%). Mutations in COQ6, NUP107, and COQ8B were more frequently detected, and mutations in NPHS2 were less commonly detected in this cohort than in study cohorts from Western countries. The mutation detection rate was higher in patients with congenital onset, those who presented with proteinuria or chronic kidney disease/ESRD, and those who did not receive steroid treatment. Genetic diagnosis in patients with SRNS provides not only definitive diagnosis but also valuable information for decisions on treatment policy and prediction of prognosis. Therefore, further genotype-phenotype correlation studies are required.
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Affiliation(s)
- Eujin Park
- Department of Pediatrics, Seoul National University College of Medicine, Seoul 03080, Korea; (E.P.); (Y.H.A.); (H.G.K.); (I.-S.H.)
- Department of Pediatrics, Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul 07441, Korea
| | - Chung Lee
- Samsung Genome Institute, Samsung Medical Center, Seoul 06351, Korea; (C.L.); (N.K.D.K.); (W.-Y.P.)
- GENINUS Inc., Seoul 05836, Korea
| | - Nayoung K. D. Kim
- Samsung Genome Institute, Samsung Medical Center, Seoul 06351, Korea; (C.L.); (N.K.D.K.); (W.-Y.P.)
- GENINUS Inc., Seoul 05836, Korea
| | - Yo Han Ahn
- Department of Pediatrics, Seoul National University College of Medicine, Seoul 03080, Korea; (E.P.); (Y.H.A.); (H.G.K.); (I.-S.H.)
| | - Young Seo Park
- Department of Pediatrics, Asan Medical Center Children’s Hospital, University of Ulsan College of Medicine, Seoul 05505, Korea; (Y.S.P.); (J.H.L.)
| | - Joo Hoon Lee
- Department of Pediatrics, Asan Medical Center Children’s Hospital, University of Ulsan College of Medicine, Seoul 05505, Korea; (Y.S.P.); (J.H.L.)
| | - Seong Heon Kim
- Department of Pediatrics, Pusan National University Children’s Hospital, Yangsan 50612, Korea;
| | - Min Hyun Cho
- Department of Pediatrics, Kyungpook National University School of Medicine, Daegu 41944, Korea;
| | - Heeyeon Cho
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea;
| | - Kee Hwan Yoo
- Department of Pediatrics, Korea University Guro Hospital, Seoul 02841, Korea;
| | - Jae Il Shin
- Department of Pediatrics, Yonsei University College of Medicine, Seoul 03722, Korea;
- Division of Pediatric Nephrology, Severance Children’s Hospital, Seoul 03722, Korea
| | - Hee Gyung Kang
- Department of Pediatrics, Seoul National University College of Medicine, Seoul 03080, Korea; (E.P.); (Y.H.A.); (H.G.K.); (I.-S.H.)
| | - Il-Soo Ha
- Department of Pediatrics, Seoul National University College of Medicine, Seoul 03080, Korea; (E.P.); (Y.H.A.); (H.G.K.); (I.-S.H.)
| | - Woong-Yang Park
- Samsung Genome Institute, Samsung Medical Center, Seoul 06351, Korea; (C.L.); (N.K.D.K.); (W.-Y.P.)
- GENINUS Inc., Seoul 05836, Korea
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon 16419, Korea
| | - Hae Il Cheong
- Department of Pediatrics, Seoul National University College of Medicine, Seoul 03080, Korea; (E.P.); (Y.H.A.); (H.G.K.); (I.-S.H.)
- Correspondence: ; Tel.: +82-2-2072-2810
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14
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Minor Glomerular Abnormalities are Associated with Deterioration of Long-Term Kidney Function and Mitochondrial Injury. J Clin Med 2019; 9:jcm9010033. [PMID: 31877839 PMCID: PMC7019622 DOI: 10.3390/jcm9010033] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 12/14/2019] [Accepted: 12/17/2019] [Indexed: 12/15/2022] Open
Abstract
Minor glomerular abnormalities (MGAs) are unclassified glomerular lesions indicated by the presence of minor structural abnormalities that are insufficient for a specific pathological diagnosis. The long-term clinical outcomes and pathogenesis have not been examined. We hypothesized that MGAs would be associated with the deterioration of long-term kidney function and increased urinary mitochondrial DNA (mtDNA) copy numbers. We retrospectively enrolled patients with MGAs, age-/sex-/estimated glomerular filtration rate (eGFR)-matched patients with immunoglobulin A nephropathy (IgAN), and similarly matched healthy controls (MHCs; n = 49 each). We analyzed the time × group interaction effects of the eGFR and compared mean annual eGFR decline rates between the groups. We prospectively enrolled patients with MGAs, age- and sex-matched patients with IgAN, and MHCs (n = 15 each) and compared their urinary mtDNA copy numbers. Compared to the MHC group, the MGA and IgAN groups displayed differences in the time × group effects of eGFR, higher mean annual rates of eGFR decline, and higher urinary mtDNA copy numbers; however, these groups did not significantly differ from each other. The results indicate that MGAs are associated with deteriorating long-term kidney function, and mitochondrial injury, despite few additional pathological changes. We suggest that clinicians conduct close long-term follow-up of patients with MGAs.
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15
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IgA nephropathy is associated with elevated urinary mitochondrial DNA copy numbers. Sci Rep 2019; 9:16068. [PMID: 31690796 PMCID: PMC6831703 DOI: 10.1038/s41598-019-52535-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 10/16/2019] [Indexed: 12/25/2022] Open
Abstract
Mitochondrial injury plays important roles in the pathogenesis of various kidney diseases. However, mitochondrial injury in IgA nephropathy (IgAN) remains largely unexplored. Here, we examined the associations among mitochondrial injury, IgAN, and treatment outcomes. We prospectively enrolled patients with IgAN and age-/sex-matched healthy volunteers (HVs) as controls (n = 31 each). Urinary copy numbers of the mitochondrial DNA (mtDNA) genes cytochrome-c oxidase-3 (COX3) and nicotinamide adenine dinucleotide dehydrogenase subunit-1 (ND1) were measured. Urinary mtDNA levels were elevated in the IgAN group compared with that in HVs (p < 0.001). Urinary ND1 levels were significantly higher in the low proteinuria group than in the high proteinuria group (p = 0.027). Changes in urinary levels of ND1 and COX3 were positively correlated with changes in proteinuria (p = 0.038 and 0.024, respectively) and inversely correlated with changes in the estimated glomerular filtration rate (p = 0.033 and 0.017, respectively) after medical treatment. Mitochondrial injury played important roles in IgAN pathogenesis and may be involved in early-stage glomerular inflammation, prior to pathological changes and increased proteinuria. The correlation between changes in urinary mtDNA and proteinuria suggest that these factors may be promising biomarkers for treatment outcomes in IgAN.
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16
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Proximal Myopathy due to m.5835G>A Mutation in Mitochondrial MT-TY Gene. Case Rep Neurol Med 2019; 2018:8406712. [PMID: 30643656 PMCID: PMC6311237 DOI: 10.1155/2018/8406712] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 10/31/2018] [Accepted: 12/02/2018] [Indexed: 11/17/2022] Open
Abstract
Mitochondrial (mt) tRNA (MTT) gene mutations are an important cause of mitochondrial diseases and are associated with a wide range of clinical presentations. Most mutations fall into three mitochondrial tRNAs (tRNAIle, tRNALeu (UUR), and tRNALys) and are responsible for half of the mitochondrial diseasees associated with tRNA mutation, with MERRF, MELAS, mitochondrial myopathy, and Leigh syndrome being the most frequent phenotypes. More than 100 tRNA pathogenetic mutations are described, showing little correlation between the observed clinical phenotype and a specific mitochondrial tRNA mutation. Furthermore different mutation can manifest with similar clinical phenotypes, making the genotype-phenotype correlation difficult. Here we report the case of an Italian 53-year-old woman presenting with a proximal myopathy and the m.5835G>A mutation in MT-TY gene coding for the mitochondrial tRNA Tyrosine gene.
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17
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de Paiva ARB, Lynch DS, Melo US, Lucato LT, Freua F, de Assis BDR, Barcelos I, Listik C, de Castro Dos Santos D, Macedo-Souza LI, Houlden H, Kok F. PUS3 mutations are associated with intellectual disability, leukoencephalopathy, and nephropathy. NEUROLOGY-GENETICS 2019; 5:e306. [PMID: 30697592 PMCID: PMC6340380 DOI: 10.1212/nxg.0000000000000306] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 11/08/2018] [Indexed: 11/27/2022]
Affiliation(s)
- Anderson Rodrigues Brandão de Paiva
- Neurogenetics Unit (A.R.B.d.P., F.F., B.D.R.d.A., I.B., C.L., D.d.C.d.S., F.K.), Neurology Department, Hospital das Clínicas da Universidade de São Paulo, Brazil; Department of Molecular Neuroscience (D.S.L., H.H.), UCL Institute of Neurology, London, UK; Leonard Wolfson Experimental Neurology Centre (D.S.L., H.H.), UCL Institute of Neurology, London, UK; Human Genome and Stem Cell Research Center (U.S.M., L.I.M.-S., F.K.), Department of Genetics and Evolutionary Biology, Instituto de Biociências, Universidade de São Paulo, Brazil; and Neuroradiology Section (L.T.L.), Hospital das Clínicas da Universidade de São Paulo, Brazil
| | - David S Lynch
- Neurogenetics Unit (A.R.B.d.P., F.F., B.D.R.d.A., I.B., C.L., D.d.C.d.S., F.K.), Neurology Department, Hospital das Clínicas da Universidade de São Paulo, Brazil; Department of Molecular Neuroscience (D.S.L., H.H.), UCL Institute of Neurology, London, UK; Leonard Wolfson Experimental Neurology Centre (D.S.L., H.H.), UCL Institute of Neurology, London, UK; Human Genome and Stem Cell Research Center (U.S.M., L.I.M.-S., F.K.), Department of Genetics and Evolutionary Biology, Instituto de Biociências, Universidade de São Paulo, Brazil; and Neuroradiology Section (L.T.L.), Hospital das Clínicas da Universidade de São Paulo, Brazil
| | - Uirá Souto Melo
- Neurogenetics Unit (A.R.B.d.P., F.F., B.D.R.d.A., I.B., C.L., D.d.C.d.S., F.K.), Neurology Department, Hospital das Clínicas da Universidade de São Paulo, Brazil; Department of Molecular Neuroscience (D.S.L., H.H.), UCL Institute of Neurology, London, UK; Leonard Wolfson Experimental Neurology Centre (D.S.L., H.H.), UCL Institute of Neurology, London, UK; Human Genome and Stem Cell Research Center (U.S.M., L.I.M.-S., F.K.), Department of Genetics and Evolutionary Biology, Instituto de Biociências, Universidade de São Paulo, Brazil; and Neuroradiology Section (L.T.L.), Hospital das Clínicas da Universidade de São Paulo, Brazil
| | - Leandro Tavares Lucato
- Neurogenetics Unit (A.R.B.d.P., F.F., B.D.R.d.A., I.B., C.L., D.d.C.d.S., F.K.), Neurology Department, Hospital das Clínicas da Universidade de São Paulo, Brazil; Department of Molecular Neuroscience (D.S.L., H.H.), UCL Institute of Neurology, London, UK; Leonard Wolfson Experimental Neurology Centre (D.S.L., H.H.), UCL Institute of Neurology, London, UK; Human Genome and Stem Cell Research Center (U.S.M., L.I.M.-S., F.K.), Department of Genetics and Evolutionary Biology, Instituto de Biociências, Universidade de São Paulo, Brazil; and Neuroradiology Section (L.T.L.), Hospital das Clínicas da Universidade de São Paulo, Brazil
| | - Fernando Freua
- Neurogenetics Unit (A.R.B.d.P., F.F., B.D.R.d.A., I.B., C.L., D.d.C.d.S., F.K.), Neurology Department, Hospital das Clínicas da Universidade de São Paulo, Brazil; Department of Molecular Neuroscience (D.S.L., H.H.), UCL Institute of Neurology, London, UK; Leonard Wolfson Experimental Neurology Centre (D.S.L., H.H.), UCL Institute of Neurology, London, UK; Human Genome and Stem Cell Research Center (U.S.M., L.I.M.-S., F.K.), Department of Genetics and Evolutionary Biology, Instituto de Biociências, Universidade de São Paulo, Brazil; and Neuroradiology Section (L.T.L.), Hospital das Clínicas da Universidade de São Paulo, Brazil
| | - Bruno Della Ripa de Assis
- Neurogenetics Unit (A.R.B.d.P., F.F., B.D.R.d.A., I.B., C.L., D.d.C.d.S., F.K.), Neurology Department, Hospital das Clínicas da Universidade de São Paulo, Brazil; Department of Molecular Neuroscience (D.S.L., H.H.), UCL Institute of Neurology, London, UK; Leonard Wolfson Experimental Neurology Centre (D.S.L., H.H.), UCL Institute of Neurology, London, UK; Human Genome and Stem Cell Research Center (U.S.M., L.I.M.-S., F.K.), Department of Genetics and Evolutionary Biology, Instituto de Biociências, Universidade de São Paulo, Brazil; and Neuroradiology Section (L.T.L.), Hospital das Clínicas da Universidade de São Paulo, Brazil
| | - Isabella Barcelos
- Neurogenetics Unit (A.R.B.d.P., F.F., B.D.R.d.A., I.B., C.L., D.d.C.d.S., F.K.), Neurology Department, Hospital das Clínicas da Universidade de São Paulo, Brazil; Department of Molecular Neuroscience (D.S.L., H.H.), UCL Institute of Neurology, London, UK; Leonard Wolfson Experimental Neurology Centre (D.S.L., H.H.), UCL Institute of Neurology, London, UK; Human Genome and Stem Cell Research Center (U.S.M., L.I.M.-S., F.K.), Department of Genetics and Evolutionary Biology, Instituto de Biociências, Universidade de São Paulo, Brazil; and Neuroradiology Section (L.T.L.), Hospital das Clínicas da Universidade de São Paulo, Brazil
| | - Clarice Listik
- Neurogenetics Unit (A.R.B.d.P., F.F., B.D.R.d.A., I.B., C.L., D.d.C.d.S., F.K.), Neurology Department, Hospital das Clínicas da Universidade de São Paulo, Brazil; Department of Molecular Neuroscience (D.S.L., H.H.), UCL Institute of Neurology, London, UK; Leonard Wolfson Experimental Neurology Centre (D.S.L., H.H.), UCL Institute of Neurology, London, UK; Human Genome and Stem Cell Research Center (U.S.M., L.I.M.-S., F.K.), Department of Genetics and Evolutionary Biology, Instituto de Biociências, Universidade de São Paulo, Brazil; and Neuroradiology Section (L.T.L.), Hospital das Clínicas da Universidade de São Paulo, Brazil
| | - Diego de Castro Dos Santos
- Neurogenetics Unit (A.R.B.d.P., F.F., B.D.R.d.A., I.B., C.L., D.d.C.d.S., F.K.), Neurology Department, Hospital das Clínicas da Universidade de São Paulo, Brazil; Department of Molecular Neuroscience (D.S.L., H.H.), UCL Institute of Neurology, London, UK; Leonard Wolfson Experimental Neurology Centre (D.S.L., H.H.), UCL Institute of Neurology, London, UK; Human Genome and Stem Cell Research Center (U.S.M., L.I.M.-S., F.K.), Department of Genetics and Evolutionary Biology, Instituto de Biociências, Universidade de São Paulo, Brazil; and Neuroradiology Section (L.T.L.), Hospital das Clínicas da Universidade de São Paulo, Brazil
| | - Lúcia Inês Macedo-Souza
- Neurogenetics Unit (A.R.B.d.P., F.F., B.D.R.d.A., I.B., C.L., D.d.C.d.S., F.K.), Neurology Department, Hospital das Clínicas da Universidade de São Paulo, Brazil; Department of Molecular Neuroscience (D.S.L., H.H.), UCL Institute of Neurology, London, UK; Leonard Wolfson Experimental Neurology Centre (D.S.L., H.H.), UCL Institute of Neurology, London, UK; Human Genome and Stem Cell Research Center (U.S.M., L.I.M.-S., F.K.), Department of Genetics and Evolutionary Biology, Instituto de Biociências, Universidade de São Paulo, Brazil; and Neuroradiology Section (L.T.L.), Hospital das Clínicas da Universidade de São Paulo, Brazil
| | - Henry Houlden
- Neurogenetics Unit (A.R.B.d.P., F.F., B.D.R.d.A., I.B., C.L., D.d.C.d.S., F.K.), Neurology Department, Hospital das Clínicas da Universidade de São Paulo, Brazil; Department of Molecular Neuroscience (D.S.L., H.H.), UCL Institute of Neurology, London, UK; Leonard Wolfson Experimental Neurology Centre (D.S.L., H.H.), UCL Institute of Neurology, London, UK; Human Genome and Stem Cell Research Center (U.S.M., L.I.M.-S., F.K.), Department of Genetics and Evolutionary Biology, Instituto de Biociências, Universidade de São Paulo, Brazil; and Neuroradiology Section (L.T.L.), Hospital das Clínicas da Universidade de São Paulo, Brazil
| | - Fernando Kok
- Neurogenetics Unit (A.R.B.d.P., F.F., B.D.R.d.A., I.B., C.L., D.d.C.d.S., F.K.), Neurology Department, Hospital das Clínicas da Universidade de São Paulo, Brazil; Department of Molecular Neuroscience (D.S.L., H.H.), UCL Institute of Neurology, London, UK; Leonard Wolfson Experimental Neurology Centre (D.S.L., H.H.), UCL Institute of Neurology, London, UK; Human Genome and Stem Cell Research Center (U.S.M., L.I.M.-S., F.K.), Department of Genetics and Evolutionary Biology, Instituto de Biociências, Universidade de São Paulo, Brazil; and Neuroradiology Section (L.T.L.), Hospital das Clínicas da Universidade de São Paulo, Brazil
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Detection of mitochondrial transfer RNA (mt-tRNA) gene mutations in patients with idiopathic pulmonary fibrosis and sarcoidosis. Mitochondrion 2018; 43:43-52. [PMID: 30473003 DOI: 10.1016/j.mito.2018.10.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2018] [Revised: 09/10/2018] [Accepted: 10/25/2018] [Indexed: 12/17/2022]
Abstract
Mitochondrial reactive oxygen species production may lead to tissue injury associated with two respiratory disorders of unknown origin which are shared by common tissue fibrosis, IPF and sarcoidosis. Sequence analysis of 22 mt-tRNA genes and parts of their flanking genes revealed 32 and 45 mutations in 38/40 IPF and 69/85 sarcoidosis patients respectively. 4 novel mutations were identified. 15/32 and 25/45 mutations were exclusively expressed while 12/32 and 17/45 mutations predominantly occurred in IPF and sarcoidosis group respectively, compared to healthy controls. Novel mutation combinations were solely expressed in disease. Hence, a mitochondrial-mediated pathogenic pathway seems to underlie both entities.
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19
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Finsterer J, Scorza FA. Renal manifestations of primary mitochondrial disorders. Biomed Rep 2017; 6:487-494. [PMID: 28515908 DOI: 10.3892/br.2017.892] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 03/31/2017] [Indexed: 12/19/2022] Open
Abstract
The aim of the present review was to summarize and discuss previous findings concerning renal manifestations of primary mitochondrial disorders (MIDs). A literature review was performed using frequently used databases. The study identified that primary MIDs frequently present as mitochondrial multiorgan disorder syndrome (MIMODS) at onset or in the later course of the MID. Occasionally, the kidneys are affected in MIDs. Renal manifestations of MIDs include renal insufficiency, nephrolithiasis, nephrotic syndrome, renal cysts, renal tubular acidosis, Bartter-like syndrome, Fanconi syndrome, focal segmental glomerulosclerosis, tubulointerstitial nephritis, nephrocalcinosis, and benign or malign neoplasms. Among the syndromic MIDs, renal involvement has been most frequently reported in patients with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes syndrome, Kearns-Sayre syndrome, Leigh syndrome and mitochondrial depletion syndromes. Only in single cases was renal involvement also reported in chronic progressive external ophthalmoplegia, Pearson syndrome, Leber's hereditary optic neuropathy, coenzyme-Q deficiency, X-linked sideroblastic anemia and ataxia, myopathy, lactic acidosis, and sideroblastic anemia, pyruvate dehydrogenase deficiency, growth retardation, aminoaciduria, cholestasis, iron overload, lactacidosis, and early death, and hyperuricemia, pulmonary hypertension, renal failure in infancy and alkalosis syndrome. The present study proposes that the frequency of renal involvement in MIDs is probably underestimated. Diagnosis of renal involvement follows general guidelines and treatment is symptomatic. Thus, renal manifestations of primary MIDs require recognition and appropriate management, as they determine the outcome of MID patients.
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Affiliation(s)
- Josef Finsterer
- Neurological Department, Municipal Hospital Rudolfstiftung, A-1030 Vienna, Austria
| | - Fulvio Alexandre Scorza
- Paulista de Medicina School, Federal University of São Paulo, Primeiro Andar CEP, São Paulo 04039-032, SP, Brazil
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20
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Focal segmental glomerulosclerosis associated with mitochondrial disease. Clin Nephrol Case Stud 2017; 5:20-25. [PMID: 29043143 PMCID: PMC5438005 DOI: 10.5414/cncs109083] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 01/06/2017] [Indexed: 12/30/2022] Open
Abstract
Primary mitochondrial diseases (MD) are complex, heterogeneous inherited diseases caused by mutations in either the mitochondrial or nuclear DNA. Glomerular diseases in MD have been reported with tRNA mutation m.3243A>G causing a syndrome of mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS). We describe here a case of focal segmental glomerulosclerosis (FSGS) associated with a new tRNA mutation site. A 34-year-old man with a history of living related kidney transplantation, diabetes, hearing loss, and developmental delay presented to the outpatient clinic with complaints of new behavioral difficulties, worsening symptoms, and brain involvement on imaging. Physical examination was remarkable for difficulty hearing, a pattern of dysarthric speech, and cerebellar gait. Laboratory investigations including lactate levels were unremarkable. Based on this set of clinical circumstances, concern for an underlying genetic abnormality was raised. Multiple metabolic tests were unremarkable. Whole exome sequencing revealed a mitochondrial MT-TW tRNA change at position m.5538G>A. Genotype-phenotype correlations are consistent with this tRNA mutation as a cause of his symptoms. To the best of our knowledge, this is the first case describing FSGS-associated MD caused by an m.5538 G>A mutation. Consideration of an underlying MD should be made in patients presenting with deafness, neurologic changes, diabetes, and renal failure.
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21
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Guo Y, Bosompem A, Mohan S, Erdogan B, Ye F, Vickers KC, Sheng Q, Zhao S, Li CI, Su PF, Jagasia M, Strickland SA, Griffiths EA, Kim AS. Transfer RNA detection by small RNA deep sequencing and disease association with myelodysplastic syndromes. BMC Genomics 2015; 16:727. [PMID: 26400237 PMCID: PMC4581457 DOI: 10.1186/s12864-015-1929-y] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 09/16/2015] [Indexed: 11/10/2022] Open
Abstract
Background Although advances in sequencing technologies have popularized the use of microRNA (miRNA) sequencing (miRNA-seq) for the quantification of miRNA expression, questions remain concerning the optimal methodologies for analysis and utilization of the data. The construction of a miRNA sequencing library selects RNA by length rather than type. However, as we have previously described, miRNAs represent only a subset of the species obtained by size selection. Consequently, the libraries obtained for miRNA sequencing also contain a variety of additional species of small RNAs. This study looks at the prevalence of these other species obtained from bone marrow aspirate specimens and explores the predictive value of these small RNAs in the determination of response to therapy in myelodysplastic syndromes (MDS). Methods Paired pre and post treatment bone marrow aspirate specimens were obtained from patients with MDS who were treated with either azacytidine or decitabine (24 pre-treatment specimens, 23 post-treatment specimens) with 22 additional non-MDS control specimens. Total RNA was extracted from these specimens and submitted for next generation sequencing after an additional size exclusion step to enrich for small RNAs. The species of small RNAs were enumerated, single nucleotide variants (SNVs) identified, and finally the differential expression of tRNA-derived species (tDRs) in the specimens correlated with diseasestatus and response to therapy. Results Using miRNA sequencing data generated from bone marrow aspirate samples of patients with known MDS (N = 47) and controls (N = 23), we demonstrated that transfer RNA (tRNA) fragments (specifically tRNA halves, tRHs) are one of the most common species of small RNA isolated from size selection. Using tRNA expression values extracted from miRNA sequencing data, we identified six tRNA fragments that are differentially expressed between MDS and normal samples. Using the elastic net method, we identified four tRNAs-derived small RNAs (tDRs) that together can explain 67 % of the variation in treatment response for MDS patients. Similar analysis of specifically mitochondrial tDRs (mt-tDRs) identified 13 mt-tDRs which distinguished disease status in the samples and a single mt-tDR which predited response. Finally, 14 SNVs within the tDRs were found in at least 20 % of the MDS samples and were not observed in any of the control specimens. Discussion This study highlights the prevalence of tDRs in RNA-seq studies focused on small RNAs. The potential etiologies of these species, both technical and biologic, are discussed as well as important challenges in the interpretation of tDR data. Conclusions Our analysis results suggest that tRNA fragments can be accurately detected through miRNA sequencing data and that the expression of these species may be useful in the diagnosis of MDS and the prediction of response to therapy. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1929-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yan Guo
- Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Amma Bosompem
- Department of Pathology, Immunology, and Microbiology, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Sanjay Mohan
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Begum Erdogan
- Department of Pathology, Immunology, and Microbiology, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Fei Ye
- Department of Biostatistics, Vanderbilt University, Nashville, TN, USA.
| | - Kasey C Vickers
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Quanhu Sheng
- Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Shilin Zhao
- Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Chung-I Li
- Department of Applied Mathematics, National Chiayi University, Chiayi City, Taiwan.
| | - Pei-Fang Su
- Department of Statistics, National Cheng Kung University, Tainan City, Taiwan.
| | - Madan Jagasia
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Stephen A Strickland
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.
| | | | - Annette S Kim
- Department of Pathology, Immunology, and Microbiology, Vanderbilt University Medical Center, Nashville, TN, USA. .,Present address: Brigham and Women's Hospital, 75 Francis Street, Boston, MA, 02115, USA.
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22
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Deltas C, Savva I, Voskarides K, Papazachariou L, Pierides A. Carriers of Autosomal Recessive Alport Syndrome with Thin Basement Membrane Nephropathy Presenting as Focal Segmental Glomerulosclerosis in Later Life. Nephron Clin Pract 2015. [PMID: 26201269 DOI: 10.1159/000435789] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Collagen IV nephropathies (COL4Ns) comprise benign familial microscopic hematuria, thin basement membrane nephropathy (TBMN), X-linked Alport syndrome (AS) and also autosomal recessive and dominant AS. Apart from the X-linked form of AS, which is caused by hemizygous mutations in the COL4A5 gene, the other entities are caused by mutations in the COL4A3 or COL4A4 genes. The diagnosis of these conditions used to be based on clinical and/or histological findings of renal biopsies, but it is the new molecular genetics approach that revolutionised their investigation and proved particularly instrumental, especially, in many not so clear-cut cases. More recently, the spectrum of COL4N has expanded to include late onset focal segmental glomerulosclerosis (FSGS) that develops on top of TBMN in later life. Also, other reports showed that some patients with a primary diagnosis of familial FSGS proved to have variants in COL4 genes. In the presence of a renal biopsy picture of FSGS and in the absence of either electron microscopy studies or molecular genetic studies that point to TBMN and COL4N, the patient and his family may be mistakenly diagnosed with hereditary FSGS leading to unnecessary further investigations, erroneous family counselling and improper corticosteroid treatment. TBMN is a frequent finding in the general population, and according to several recent reports, it may be the underlying cause and the explanation for many familial and sporadic cases of late-onset FSGS with non-nephrotic proteinuria. This is an important new finding that needs widespread recognition. It is anticipated that the molecular genetic analysis with next generation sequencing will certainly offer timely correct diagnosis.
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Affiliation(s)
- Constantinos Deltas
- Molecular Medicine Research Center and Laboratory of Molecular and Medical Genetics, Department of Biological Sciences, University of Cyprus, Nicosia, Cyprus
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23
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Che R, Yuan Y, Huang S, Zhang A. Mitochondrial dysfunction in the pathophysiology of renal diseases. Am J Physiol Renal Physiol 2014; 306:F367-78. [PMID: 24305473 DOI: 10.1152/ajprenal.00571.2013] [Citation(s) in RCA: 286] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Mitochondrial dysfunction has gained recognition as a contributing factor in many diseases. The kidney is a kind of organ with high energy demand, rich in mitochondria. As such, mitochondrial dysfunction in the kidney plays a critical role in the pathogenesis of kidney diseases. Despite the recognized importance mitochondria play in the pathogenesis of the diseases, there is limited understanding of various aspects of mitochondrial biology. This review examines the physiology and pathophysiology of mitochondria. It begins by discussing mitochondrial structure, mitochondrial DNA, mitochondrial reactive oxygen species production, mitochondrial dynamics, and mitophagy, before turning to inherited mitochondrial cytopathies in kidneys (inherited or sporadic mitochondrial DNA or nuclear DNA mutations in genes that affect mitochondrial function). Glomerular diseases, tubular defects, and other renal diseases are then discussed. Next, acquired mitochondrial dysfunction in kidney diseases is discussed, emphasizing the role of mitochondrial dysfunction in the pathogenesis of chronic kidney disease and acute kidney injury, as their prevalence is increasing. Finally, it summarizes the possible beneficial effects of mitochondrial-targeted therapeutic agents for treatment of mitochondrial dysfunction-mediated kidney injury-genetic therapies, antioxidants, thiazolidinediones, sirtuins, and resveratrol-as mitochondrial-based drugs may offer potential treatments for renal diseases.
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Affiliation(s)
- Ruochen Che
- Department of Nephrology, Nanjing Children's Hospital, Affiliated with Nanjing Medical University, Nanjing, China
- Institute of Pediatrics, Nanjing Medical University, Nanjing, China; and
| | - Yanggang Yuan
- Department of Nephrology, First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Songming Huang
- Department of Nephrology, Nanjing Children's Hospital, Affiliated with Nanjing Medical University, Nanjing, China
- Institute of Pediatrics, Nanjing Medical University, Nanjing, China; and
| | - Aihua Zhang
- Department of Nephrology, Nanjing Children's Hospital, Affiliated with Nanjing Medical University, Nanjing, China
- Institute of Pediatrics, Nanjing Medical University, Nanjing, China; and
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24
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Abstract
Mitochondrial diseases can be related to mutations in either the nuclear or mitochondrial genome. Childhood presentations are commonly associated with renal tubular dysfunction, but renal involvement is less commonly reported outside of this age-group. Mitochondrial diseases are notable for the significant variability in their clinical presentation and the broad spectrum of genes implicated in their etiology. These features contribute to the challenges of establishing a definitive diagnosis and understanding the pathogenetic mechanisms leading to kidney involvement in these diseases. Here, we review the deoxyribonucleic acid variants in the mitochondrial and nuclear genomes that have been associated with a kidney phenotype, and examine some of the possible pathogenic mechanisms that may contribute to the expression of a renal phenotype.
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Affiliation(s)
- John F O'Toole
- Department of Internal Medicine, Division of Nephrology, MetroHealth Medical System, Case Western Reserve University School of Medicine, Cleveland, OH, USA
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25
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Gasser DL, Winkler CA, Peng M, An P, McKenzie LM, Kirk GD, Shi Y, Xie LX, Marbois BN, Clarke CF, Kopp JB. Focal segmental glomerulosclerosis is associated with a PDSS2 haplotype and, independently, with a decreased content of coenzyme Q10. Am J Physiol Renal Physiol 2013; 305:F1228-38. [PMID: 23926186 PMCID: PMC3798722 DOI: 10.1152/ajprenal.00143.2013] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 08/05/2013] [Indexed: 11/22/2022] Open
Abstract
Focal segmental glomerulosclerosis (FSGS) and collapsing glomerulopathy are common causes of nephrotic syndrome. Variants in >20 genes, including genes critical for mitochondrial function, have been associated with these podocyte diseases. One such gene, PDSS2, is required for synthesis of the decaprenyl tail of coenzyme Q10 (Q10) in humans. The mouse gene Pdss2 is mutated in the kd/kd mouse model of collapsing glomerulopathy. We examined the hypothesis that human PDSS2 polymorphisms are associated with podocyte diseases. We genotyped 377 patients with primary FSGS or collapsing glomerulopathy, together with 900 controls, for 9 single-nucleotide polymorphisms in the PDSS2 gene in a case-control study. Subjects included 247 African American (AA) and 130 European American (EA) patients and 641 AA and 259 EA controls. Among EAs, a pair of proxy SNPs was significantly associated with podocyte disease, and patients homozygous for one PDSS2 haplotype had a strongly increased risk for podocyte disease. By contrast, the distribution of PDSS2 genotypes and haplotypes was similar in AA patients and controls. Thus a PDSS2 haplotype, which has a frequency of 13% in the EA control population and a homozygote frequency of 1.2%, is associated with a significantly increased risk for FSGS and collapsing glomerulopathy in EAs. Lymphoblastoid cell lines from FSGS patients had significantly less Q10 than cell lines from controls; contrary to expectation, this finding was independent of PDSS2 haplotype. These results suggest that FSGS patients have Q10 deficiency and that this deficiency is manifested in patient-derived lymphoblastoid cell lines.
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Affiliation(s)
- David L Gasser
- Dept. of Genetics, Univ. of Pennsylvania School of Medicine, 415 Curie Blvd., Philadelphia, PA 19104.
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26
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Shahni R, Wedatilake Y, Cleary MA, Lindley KJ, Sibson KR, Rahman S. A distinct mitochondrial myopathy, lactic acidosis and sideroblastic anemia (MLASA) phenotype associates with YARS2 mutations. Am J Med Genet A 2013; 161A:2334-8. [PMID: 23918765 PMCID: PMC3884767 DOI: 10.1002/ajmg.a.36065] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Accepted: 05/02/2013] [Indexed: 01/19/2023]
Abstract
Nuclear-encoded disorders of mitochondrial translation are clinically and genetically heterogeneous. Genetic causes include defects of mitochondrial aminoacyl-tRNA synthetases, and factors required for initiation, elongation and termination of protein synthesis as well as ribosome recycling. We report on a new case of myopathy, lactic acidosis and sideroblastic anemia (MLASA) syndrome caused by defective mitochondrial tyrosyl aminoacylation. The patient presented at 1 year with anemia initially attributed to iron deficiency. Bone marrow aspirate at 5 years revealed ringed sideroblasts but transfusion dependency did not occur until 11 years. Other clinical features included lactic acidosis, poor weight gain, hypertrophic cardiomyopathy and severe myopathy leading to respiratory failure necessitating ventilatory support. Long-range PCR excluded mitochondrial DNA rearrangements. Clinical diagnosis of MLASA prompted direct sequence analysis of the YARS2 gene encoding the mitochondrial tyrosyl-tRNA synthetase, which revealed homozygosity for a known pathogenic mutation, c.156C>G;p.F52L. Comparison with four previously reported cases demonstrated remarkable clinical homogeneity. First line investigation of MLASA should include direct sequence analysis of YARS2 and PUS1 (encoding a tRNA modification factor) rather than muscle biopsy. Early genetic diagnosis is essential for counseling and to facilitate appropriate supportive therapy. Reasons for segregation of specific clinical phenotypes with particular mitochondrial aminoacyl tRNA-synthetase defects remain unknown. © 2013 Wiley Periodicals, Inc.
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Affiliation(s)
- Rojeen Shahni
- Mitochondrial Research Group, Clinical and Molecular Genetics Unit, UCL Institute of Child HealthLondon, UK
| | - Yehani Wedatilake
- Mitochondrial Research Group, Clinical and Molecular Genetics Unit, UCL Institute of Child HealthLondon, UK
| | | | - Keith J Lindley
- Gastroenterology Unit, Great Ormond Street HospitalLondon, UK
| | - Keith R Sibson
- Haematology Unit, Great Ormond Street HospitalLondon, UK
| | - Shamima Rahman
- Mitochondrial Research Group, Clinical and Molecular Genetics Unit, UCL Institute of Child HealthLondon, UK
- Metabolic Unit, Great Ormond Street HospitalLondon, UK
- *Correspondence to:, Dr. Shamima Rahman, Mitochondrial Research Group, Clinical and Molecular Genetics Unit, UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK., E-mail:
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27
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Mitochondrial DNA variations in Madras motor neuron disease. Mitochondrion 2013; 13:721-8. [PMID: 23419391 DOI: 10.1016/j.mito.2013.02.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Revised: 02/06/2013] [Accepted: 02/08/2013] [Indexed: 11/20/2022]
Abstract
Although the Madras motor neuron disease (MMND) was found three decades ago, its genetic basis has not been elucidated, so far. The symptom at onset was impaired hearing, upper limb weakness and atrophy. Since some clinical features of MMND overlap with mitochondrial disorders, we analyzed the complete mitochondrial genome of 45 MMND patients and found 396 variations, including 13 disease-associated, 2 mt-tRNA and 33 non-synonymous (16 MT-ND, 10 MT-CO, 3 MT-CYB and 4 MT-ATPase). A rare variant (m.8302A>G) in mt-tRNA(Leu) was found in three patients. We predict that these variation(s) may influence the disease pathogenesis along with some unknown factor(s).
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28
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Progress in pathogenesis of proteinuria. Int J Nephrol 2012; 2012:314251. [PMID: 22693670 PMCID: PMC3368192 DOI: 10.1155/2012/314251] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2012] [Revised: 03/24/2012] [Accepted: 03/26/2012] [Indexed: 02/06/2023] Open
Abstract
Aims. Proteinuria not only is a sign of kidney damage, but also is involved in the progression of renal diseases as an independent pathologic factor. Clinically, glomerular proteinuria is most commonly observed, which relates to structural and functional anomalies in the glomerular filtration barrier. The aim of this paper was to describe the pathogenesis of glomerular proteinuria. Data Sources. Articles on glomerular proteinuria retrieved from Pubmed and MEDLINE in the recent 5 years were reviewed. Results. The new understanding of the roles of glomerular endothelial cells and the glomerular basement membrane (GBM) in the pathogenesis of glomerular proteinuria was gained. The close relationships of slit diaphragm (SD) molecules such as nephrin, podocin, CD2-associated protein (CD2AP), a-actinin-4, transient receptor potential cation channel 6 (TRPC6), Densin and membrane-associated guanylate kinase inverted 1 (MAGI-1), α3β1 integrin, WT1, phospholipase C epsilon-1 (PLCE1), Lmx1b, and MYH9, and mitochondrial disorders and circulating factors in the pathogenesis of glomerular proteinuria were also gradually discovered. Conclusion. Renal proteinuria is a manifestation of glomerular filtration barrier dysfunction. Not only glomerular endothelial cells and GBM, but also the glomerular podocytes and their SDs play an important role in the pathogenesis of glomerular proteinuria.
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29
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Sasarman F, Nishimura T, Thiffault I, Shoubridge EA. A novel mutation in YARS2 causes myopathy with lactic acidosis and sideroblastic anemia. Hum Mutat 2012; 33:1201-6. [PMID: 22504945 DOI: 10.1002/humu.22098] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Accepted: 03/30/2012] [Indexed: 11/08/2022]
Abstract
Mutations in the mitochondrial aminoacyl-tRNA synthetases (ARSs) are associated with a strikingly broad range of clinical phenotypes, the molecular basis for which remains obscure. Here, we report a novel missense mutation (c.137G>A, p.Gly46Asp) in the catalytic domain of YARS2, which codes for the mitochondrial tyrosyl-tRNA synthetase, in a subject with myopathy, lactic acidosis, and sideroblastic anemia (MLASA). YARS2 was undetectable by immunoblot analysis in subject myoblasts, resulting in a generalized mitochondrial translation defect. Retroviral expression of a wild-type YARS2 complementary DNA completely rescued the translation defect. We previously demonstrated that the respiratory chain defect in this subject was only present in fully differentiated muscle, and we show here that this likely reflects an increased requirement for YARS2 as muscle cells differentiate. An additional, heterozygous mutation was detected in TRMU/MTU1, a gene encoding the mitochondrial 2-thiouridylase. Although subject myoblasts and myotubes contained half the normal levels of TRMU, thiolation of mitochondrial tRNAs was normal. YARS2 eluted as part of high-molecular-weight complexes of ∼250 kDa and 1 MDa by gel filtration. This study confirms mutations in YARS2 as a cause of MLASA and shows that, like some of the cytoplasmic ARSs, mitochondrial ARSs occur in high-molecular-weight complexes.
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Affiliation(s)
- Florin Sasarman
- Montreal Neurological Institute, McGill University, Montreal, Canada
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30
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Garg P, Rabelink T. Glomerular proteinuria: a complex interplay between unique players. Adv Chronic Kidney Dis 2011; 18:233-42. [PMID: 21782129 DOI: 10.1053/j.ackd.2011.06.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 05/31/2011] [Accepted: 06/01/2011] [Indexed: 11/11/2022]
Abstract
Protein leak in the urine is a harbinger of disruption of the glomerular filtration barrier. It also correlates with disease progression and development of ESRD. At present, therapies are aimed at decreasing proteinuria to decrease further damage to the filter and as a marker of remission. Understanding the mechanism of molecular events that lead to protein leak is vital to developing new therapeutic interventions. There has been tremendous progress over the last decade in identifying gene defects which result in hereditary proteinuric defects. This has led to identifying pathways by which these genes regulate the structure and function of the components of the filtration barrier, namely the podocytes, mesangial cells, endothelial cells, and the basement membrane. Using gene knockout mouse models, a role of tubular cells in regulating proteinuria is also emerging. In this review, we have attempted to present some of the prevailing understanding of the underlying mechanisms and physiology of proteinuria.
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31
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McKnight AJ, Currie D, Maxwell AP. Unravelling the genetic basis of renal diseases; from single gene to multifactorial disorders. J Pathol 2010; 220:198-216. [PMID: 19882676 DOI: 10.1002/path.2639] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Chronic kidney disease is common with up to 5% of the adult population reported to have an estimated glomerular filtration rate of < 60 ml/min/1.73 m(2). A large number of pathogenic mutations have been identified that are responsible for 'single gene' renal disorders, such as autosomal dominant polycystic kidney disease and X-linked Alport syndrome. These single gene disorders account for < 15% of the burden of end-stage renal disease that requires dialysis or kidney transplantation. It has proved more difficult to identify the genetic susceptibility underlying common, complex, multifactorial kidney conditions, such as diabetic nephropathy and hypertensive nephrosclerosis. This review describes success to date and explores strategies currently employed in defining the genetic basis for a number of renal disorders. The complementary use of linkage studies, candidate gene and genome-wide association analyses are described and a collation of renal genetic resources highlighted.
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Affiliation(s)
- Amy J McKnight
- Nephrology Research Group, Queen's University of Belfast, Belfast BT9 7AB, Northern Ireland, UK
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32
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Molecular genetic analysis of podocyte genes in focal segmental glomerulosclerosis--a review. Eur J Pediatr 2009; 168:1291-304. [PMID: 19562370 PMCID: PMC2745545 DOI: 10.1007/s00431-009-1017-x] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2009] [Accepted: 06/12/2009] [Indexed: 01/15/2023]
Abstract
This review deals with podocyte proteins that play a significant role in the structure and function of the glomerular filter. Genetic linkage studies has identified several genes involved in the development of nephrotic syndrome and contributed to the understanding of the pathophysiology of glomerular proteinuria and/or focal segmental glomerulosclerosis. Here, we describe already well-characterized genetic diseases due to mutations in nephrin, podocin, CD2AP, alpha-actinin-4, WT1, and laminin beta2 chain, as well as more recently identified genetic abnormalities in TRPC6, phospholipase C epsilon, and the proteins encoded by the mitochondrial genome. In addition, the role of the proteins which have shown to be important for the structure and functions by gene knockout studies in mice, are also discussed. Furthermore, some rare syndromes with glomerular involvement, in which molecular defects have been recently identified, are briefly described. In summary, this review updates the current knowledge of genetic causes of congenital and childhood nephrotic syndrome and provides new insights into mechanisms of glomerular dysfunction.
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33
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Baranowska I, Jäderlund KH, Nennesmo I, Holmqvist E, Heidrich N, Larsson NG, Andersson G, Wagner EGH, Hedhammar Å, Wibom R, Andersson L. Sensory ataxic neuropathy in golden retriever dogs is caused by a deletion in the mitochondrial tRNATyr gene. PLoS Genet 2009; 5:e1000499. [PMID: 19492087 PMCID: PMC2683749 DOI: 10.1371/journal.pgen.1000499] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2009] [Accepted: 04/30/2009] [Indexed: 11/18/2022] Open
Abstract
Sensory ataxic neuropathy (SAN) is a recently identified neurological disorder in golden retrievers. Pedigree analysis revealed that all affected dogs belong to one maternal lineage, and a statistical analysis showed that the disorder has a mitochondrial origin. A one base pair deletion in the mitochondrial tRNA(Tyr) gene was identified at position 5304 in affected dogs after re-sequencing the complete mitochondrial genome of seven individuals. The deletion was not found among dogs representing 18 different breeds or in six wolves, ruling out this as a common polymorphism. The mutation could be traced back to a common ancestor of all affected dogs that lived in the 1970s. We used a quantitative oligonucleotide ligation assay to establish the degree of heteroplasmy in blood and tissue samples from affected dogs and controls. Affected dogs and their first to fourth degree relatives had 0-11% wild-type (wt) sequence, while more distant relatives ranged between 5% and 60% wt sequence and all unrelated golden retrievers had 100% wt sequence. Northern blot analysis showed that tRNA(Tyr) had a 10-fold lower steady-state level in affected dogs compared with controls. Four out of five affected dogs showed decreases in mitochondrial ATP production rates and respiratory chain enzyme activities together with morphological alterations in muscle tissue, resembling the changes reported in human mitochondrial pathology. Altogether, these results provide conclusive evidence that the deletion in the mitochondrial tRNA(Tyr) gene is the causative mutation for SAN.
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Affiliation(s)
- Izabella Baranowska
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Karin Hultin Jäderlund
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
- Department of Companion Animal Clinical Sciences, Norwegian School of Veterinary Science, Oslo, Norway
| | - Inger Nennesmo
- Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Erik Holmqvist
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Nadja Heidrich
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Nils-Göran Larsson
- Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Göran Andersson
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | | | - Åke Hedhammar
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Rolf Wibom
- Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Leif Andersson
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
- * E-mail:
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34
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Multisystem manifestations of mitochondrial disorders. J Neurol 2009; 256:693-710. [DOI: 10.1007/s00415-009-5028-3] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2008] [Accepted: 11/11/2008] [Indexed: 01/13/2023]
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35
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Scaglia F, Wong LJC. Human mitochondrial transfer RNAs: role of pathogenic mutation in disease. Muscle Nerve 2008; 37:150-71. [PMID: 17999409 DOI: 10.1002/mus.20917] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The human mitochondrial genome encodes 13 proteins. All are subunits of the respiratory chain complexes involved in energy metabolism. These proteins are translated by a set of 22 mitochondrial transfer RNAs (tRNAs) that are required for codon reading. Human mitochondrial tRNA genes are hotspots for pathogenic mutations and have attracted interest over the last two decades with the rapid discovery of point mutations associated with a vast array of neuromuscular disorders and diverse clinical phenotypes. In this review, we use a scoring system to determine the pathogenicity of the mutations and summarize the current knowledge of structure-function relationships of these mutant tRNAs. We also provide readers with an overview of a large variety of mechanisms by which mutations may affect the mitochondrial translation machinery and cause disease.
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Affiliation(s)
- Fernando Scaglia
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA
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36
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Bonnefond L, Florentz C, Giegé R, Rudinger-Thirion J. Decreased aminoacylation in pathology-related mutants of mitochondrial tRNATyr is associated with structural perturbations in tRNA architecture. RNA (NEW YORK, N.Y.) 2008; 14:641-648. [PMID: 18268021 PMCID: PMC2271369 DOI: 10.1261/rna.938108] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2007] [Accepted: 12/19/2007] [Indexed: 05/25/2023]
Abstract
A growing number of human pathologies are ascribed to mutations in mitochondrial tRNA genes. Here, we report biochemical investigations on three mt-tRNA(Tyr) molecules with point substitutions associated with diseases. The mutations occur in the atypical T- and D-loops at positions homologous to those involved in the tertiary interaction network of canonical tRNAs. They do not correspond to tyrosine identity positions and likely do not contact the mitochondrial tyrosyl-tRNA synthetase during the aminoacylation process. The impact of these substitutions on mt-tRNA(Tyr) tyrosylation and structure was investigated using the corresponding tRNA transcripts. In vitro tyrosylation efficiency is decreased 600-fold for mutant A22G (mitochondrial gene mutation T5874C), 40-fold for G15A (C5877T), and is without significant effect on U54C (A5843G). Comparative solution probings with lead and nucleases on mutant and wild-type tRNA(Tyr) molecules reveal a greater sensitivity to single-strand specific probes for mutants G15A and A22G. For both transcripts, the mutation triggers a structural destabilization in the D-loop that propagates toward the anticodon arm and thus hinders efficient tyrosylation. Further probing analysis combined with phylogenetic data support the participation of G15 and A22 in the tertiary network of human mt-tRNA(Tyr) via nonclassical Watson-Crick G15-C48 and G13-A22 pairings. In contrast, the pathogenic effect of the tyrosylable mutant U54C, where structure is only marginally affected, has to be sought at another level of the tRNA(Tyr) life cycle.
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Affiliation(s)
- Luc Bonnefond
- Architecture et Réactivité de l'ARN, Université Louis Pasteur de Strasbourg, CNRS, 67084 Strasbourg, France
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37
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Barisoni L, Diomedi-Camassei F, Santorelli FM, Caridi G, Thomas DB, Emma F, Piemonte F, Ghiggeri GM. Collapsing glomerulopathy associated with inherited mitochondrial injury. Kidney Int 2008; 74:237-43. [PMID: 18235438 DOI: 10.1038/sj.ki.5002767] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Laura Barisoni
- Department of Pathology and Medicine, School of Medicine, New York University, New York, New York 10016, USA.
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38
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Bandelt HJ, Salas A, Bravi CM. What is a 'novel' mtDNA mutation--and does 'novelty' really matter? J Hum Genet 2006; 51:1073-1082. [PMID: 17021933 DOI: 10.1007/s10038-006-0066-5] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2006] [Accepted: 08/29/2006] [Indexed: 01/08/2023]
Abstract
The hunt for pathogenic mitochondrial DNA (mtDNA) mutations is often fueled by the seeming novelty of mutations that are either nonsynonymous or affect the protein synthesis machinery in patients. In order to determine the novelty of a detected mutation, the working geneticist nearly always consults MITOMAP--often exclusively. By reanalyzing some case studies of refractory anemia with ring sideroblasts, prostate cancer, and hearing impairment, we demonstrate that the practice of solely relying on MITOMAP can be most misleading. A notorious example is the T1243C mutation, which was assessed to be novel and deemed to be associated with some (rare) disease simply because researchers did not realize that T1243C defines a deep branch in the Eurasian mtDNA phylogeny. The majority of 'novel' mutations suspected of being pathogenic are in actual fact known (and presumably neutral) polymorphisms (although unknown to MITOMAP), and this becomes glaringly evident when proper database searches and straightforward Internet queries are carried out.
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Affiliation(s)
- Hans-Jürgen Bandelt
- Department of Mathematics, University of Hamburg, Bundesstr. 55, 20146, Hamburg, Germany.
| | - Antonio Salas
- Unidad de Genética, Instituto de Medicina Legal, Facultad de Medicina, Universidad de Santiago de Compostela, 15782, Galicia, Spain
- Centro Nacional de Genotipado (CeGen), Hospital Clínico Universitario, 15706, Galicia, Spain
| | - Claudio M Bravi
- Laboratorio de Genética Molecular Poblacional, Instituto Multidisciplinario de Biología Celular (IMBICE), P.O. Box 403, 1900, La Plata, Argentina
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Abstract
Collapsing glomerulopathy (CG) has become an important cause of ESRD. First delineated from other proteinuric glomerular lesions in the 1980s, CG is now recognized as a common, distinct pattern of proliferative parenchymal injury that portends a rapid loss of renal function and poor responses to empiric therapy. Notwithstanding, the rise in disorders that are associated with CG, the identification of the first susceptibility genes for CG, the remarkable increase in murine modeling of CG, and promising preclinical testing of new therapeutic strategies suggest that the outlook for CG as a poorly understood and therapeutically resistant renal disease is set to change in the future. This focused review highlights recent advances in research into the pathogenesis and treatment of CG.
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Affiliation(s)
- Mamdouh Albaqumi
- Division of Nephrology, NYU School of Medicine, Smilow Research Center, 522 First Avenue, New York, NY 10016, USA
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Laakkonen H, Lönnqvist T, Uusimaa J, Qvist E, Valanne L, Nuutinen M, Ala-Houhala M, Majamaa K, Jalanko H, Holmberg C. Muscular dystonia and athetosis in six patients with congenital nephrotic syndrome of the Finnish type (NPHS1). Pediatr Nephrol 2006; 21:182-9. [PMID: 16362719 DOI: 10.1007/s00467-005-2116-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2005] [Revised: 08/25/2005] [Accepted: 08/29/2005] [Indexed: 11/24/2022]
Abstract
Congenital nephrotic syndrome of the Finnish type (NPHS1, CNF) is an autosomal recessively inherited disease occurring due to mutations in the nephrin gene (NPHS1). Two main Finnish mutations exist: Fin-major and minor, which both cause a lack of nephrin and absence of the slit diaphragm between the podocytes. This leads to severe proteinuria, nephrotic syndrome and infections, and without dialysis or renal transplantation, death in infancy. Between 1984 and 2003, six (8.6%) of the 70 NPHS1 patients diagnosed at our institution had, in addition to their renal disease, similar neurological symptoms. All six showed a severe dyskinetic cerebral palsy-like syndrome with dystonic features, athetosis and a hearing defect. The neurological symptoms became apparent during their 1st year of life and were diagnosed before 11 months of age. MRI showed increased signal intensity in T2-weighted images in the globus pallidus area. No mitochondrial gene mutations explaining the neurological symptoms were found, nor did external neurological complications explain them when compared with 29 NPHS1 control patients. Four children died at an early age: two during dialysis and two shortly after renal transplantation. Two are still alive with a functioning graft. Both have severe motor defects, but are mentally active and social.
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Affiliation(s)
- Hanne Laakkonen
- Department of Pediatric Nephrology and Transplantation, Hospital for Children and Adolescents, University of Helsinki, Stenbäckinkatu 11, 00290 Helsinki, Finland.
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Güçer S, Talim B, Aşan E, Korkusuz P, Ozen S, Unal S, Kalkanoğlu SH, Kale G, Cağlar M. Focal segmental glomerulosclerosis associated with mitochondrial cytopathy: report of two cases with special emphasis on podocytes. Pediatr Dev Pathol 2005; 8:710-7. [PMID: 16328667 DOI: 10.1007/s10024-005-0058-z] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2005] [Accepted: 07/28/2005] [Indexed: 10/25/2022]
Abstract
We report two children with focal segmental glomerulosclerosis (FSGS) associated with mitochondrial cytopathy (MC). Case 1 was diagnosed as MC with the findings of ptosis, ophthalmoplegia, failure to thrive, high serum lactate and pyruvate levels, ragged red fibers in muscle biopsy and the common 4.9 kb deletion in mtDNA when she was four years old. She subsequently developed FSGS four years later. Case 2 was a four month-old girl presenting with feeding difficulty from birth, with vomiting, seizures and nystagmoid eye movements, nephrotic proteinuria and hematuria. Renal biopsy revealed FSGS. Ultrastructural study demonstrated markedly pleomorphic mitochondria in podocytes with a severe effacement of foot processes. The analyses of muscle biopsy and skin fibroblasts for respiratory chain enzymes were found to be normal, while mitochondrial DNA analysis revealed the population of a single deleted mtDNA in the heteroplasmic state. The present cases illustrate FSGS as a rare renal complication of mitochondrial disease and provide further evidence of podocytes possessing abnormal mitochondria which may cause glomerular epithelial cell damage leading to glomerulosclerosis.
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Affiliation(s)
- Safak Güçer
- Department of Pediatrics, Pathology Unit, Hacettepe University Faculty of Medicine, Ankara 06100, Turkey.
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Barisoni L, Madaio MP, Eraso M, Gasser DL, Nelson PJ. The kd/kd mouse is a model of collapsing glomerulopathy. J Am Soc Nephrol 2005; 16:2847-51. [PMID: 16120817 PMCID: PMC1440888 DOI: 10.1681/asn.2005050494] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Collapsing glomerulopathy (CG) is associated with disorders that markedly perturb the phenotype of podocytes. The kd/kd mouse has been studied for immune and genetic causes of microcystic tubulointerstitial nephritis with little attention to its glomerular lesion. Because histologic examination revealed classic morphologic features of CG, the question arises whether podocytes in kd/kd mice exhibit additional phenotypic criteria for CG. Utilizing Tg26 mice as a positive control, immunohistochemical profiling of the podocyte phenotype was conducted simultaneously on both models. Similar to Tg26 kidneys, podocytes in kd/kd kidneys showed de novo cyclin D1, Ki-67, and desmin expression with loss of synaptopodin and WT-1 expression. Electron micrographs showed collapsed capillaries, extensive foot process effacement, and dysmorphic mitochondria in podocytes. These results indicate that the kd/kd mouse is a model of CG and raise the possibility that human equivalents of the kd susceptibility gene may exist in patients with CG.
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Affiliation(s)
| | | | - Maria Eraso
- Division of Nephrology, New York University School of Medicine, New York, New York; and the
| | - David L. Gasser
- Department of Genetics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Peter J. Nelson
- Division of Nephrology, New York University School of Medicine, New York, New York; and the
- Address correspondence to: Dr. Peter J. Nelson, Division of Nephrology, New York University School of Medicine, OBV-CD696, 550 First Avenue, New York, NY 10016. Phone: 212-263-7681; Fax: 212-263-7683; E-mail:
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McFarland R, Taylor RW, Elson JL, Lightowlers RN, Turnbull DM, Howell N. Proving pathogenicity: when evolution is not enough. Am J Med Genet A 2005; 131:107-8; author reply 109-10. [PMID: 15384096 DOI: 10.1002/ajmg.a.30318] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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