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Watanabe D, Okamoto N, Kobayashi Y, Suzuki H, Kato M, Saitoh S, Kanemura Y, Takenouchi T, Yamada M, Nakato D, Sato M, Tsunoda T, Kosaki K, Miya F. Biallelic structural variants in three patients with ERCC8-related Cockayne syndrome and a potential pitfall of copy number variation analysis. Sci Rep 2024; 14:19741. [PMID: 39187681 PMCID: PMC11347644 DOI: 10.1038/s41598-024-70831-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Accepted: 08/21/2024] [Indexed: 08/28/2024] Open
Abstract
Cockayne syndrome (CS) is a rare autosomal recessive disorder caused by mutations in ERCC8 or ERCC6. Most pathogenic variants in ERCC8 are single nucleotide substitutions. Structural variants (SVs) have been reported in patients with ERCC8-related CS. However, comprehensive molecular detection, including SVs of ERCC8, in CS patients remains problematic. Herein, we present three Japanese patients with ERCC8-related CS in whom causative SVs were identified using whole-exome-based copy number variation (CNV) detection tools. One patient showed compound heterozygosity for a 259-kb deletion and a deletion of exon 4 which has previously been reported as an Asia-specific variant. The other two patients were homozygous for the same exon 4 deletion. The exon 4 deletion was detected only by the ExomeDepth software. Intrigued by the discrepancy in the detection capability of various tools for the SVs, we evaluated the analytic performance of four whole-exome-based CNV detection tools using an exome data set from 337 healthy individuals. A total of 1,278,141 exons were predicted as being affected by the 4 CNV tools. Interestingly 95.1% of these affected exons were detected by one tool alone. Thus, we expect that the use of multiple tools may improve the detection rate of SVs from aligned exome data.
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Affiliation(s)
- Daisuke Watanabe
- Center for Medical Genetics, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo, 160-8582, Japan
- Department of Pediatrics, Yamanashi University, Yamanashi, Japan
| | - Nobuhiko Okamoto
- Department of Medical Genetics, Osaka Women's and Children's Hospital, Osaka, Japan
| | - Yuichi Kobayashi
- Professional Development Center, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
| | - Hisato Suzuki
- Center for Medical Genetics, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo, 160-8582, Japan
- Department of Clinical Medicine, Institute of Medicine, University of Tsukuba, Ibaraki, Japan
| | - Mitsuhiro Kato
- Department of Pediatrics, Showa University School of Medicine, Tokyo, Japan
- Epilepsy Medical Center, Showa University Hospital, Tokyo, Japan
| | - Shinji Saitoh
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Yonehiro Kanemura
- Department of Biomedical Research and Innovation, Institute for Clinical Research, NHO Osaka National Hospital, Osaka, Japan
- Department of Neurosurgery, NHO Osaka National Hospital, Osaka, Japan
| | - Toshiki Takenouchi
- Department of Pediatrics, Keio University School of Medicine, Tokyo, Japan
| | - Mamiko Yamada
- Center for Medical Genetics, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo, 160-8582, Japan
| | - Daisuke Nakato
- Center for Medical Genetics, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo, 160-8582, Japan
| | - Masayuki Sato
- Center for Medical Genetics, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo, 160-8582, Japan
| | - Tatsuhiko Tsunoda
- Laboratory for Medical Science Mathematics, Department of Biological Sciences, School of Science, The University of Tokyo, Tokyo, Japan
- Laboratory for Medical Science Mathematics, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Kenjiro Kosaki
- Center for Medical Genetics, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo, 160-8582, Japan
| | - Fuyuki Miya
- Center for Medical Genetics, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo, 160-8582, Japan.
- Innovative Human Resource Development Division, Institute of Education, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
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Marshall AE, Brady L, Yeh E, Mears AJ, Lacaria M, Chakraborty P, Tarnopolsky MA, Kernohan KD. Next generation sequencing reveals novel compound heterozygous deletions in NDUFAF2 in a child with mitochondrial complex I deficiency, nuclear type 10. Am J Med Genet A 2024:e63590. [PMID: 38477541 DOI: 10.1002/ajmg.a.63590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 02/28/2024] [Accepted: 03/01/2024] [Indexed: 03/14/2024]
Affiliation(s)
- Aren E Marshall
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Lauren Brady
- Division of Neuromuscular & Neurometabolic Disorders, Department of Pediatrics, McMaster University, Hamilton Health Sciences Centre, Hamilton, Ontario, Canada
| | - Ed Yeh
- Newborn Screening Ontario, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
| | - Alan J Mears
- Newborn Screening Ontario, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
| | - Melanie Lacaria
- Newborn Screening Ontario, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
| | - Pranesh Chakraborty
- Newborn Screening Ontario, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
| | - Mark A Tarnopolsky
- Division of Neuromuscular & Neurometabolic Disorders, Department of Pediatrics, McMaster University, Hamilton Health Sciences Centre, Hamilton, Ontario, Canada
| | - Kristin D Kernohan
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada
- Newborn Screening Ontario, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
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Sabharwal A, Gupta V, Kv S, Kumar Manokaran R, Verma A, Mishra A, Bhoyar RC, Jain A, Sivadas A, Rawat S, Jolly B, Mohanty S, Gulati S, Gupta N, Kabra M, Scaria V, Sivasubbu S. Whole genome sequencing followed by functional analysis of genomic deletion encompassing ERCC8 and NDUFAF2 genes in a non-consanguineous Indian family reveals dysfunctional mitochondrial bioenergetics leading to infant mortality. Mitochondrion 2024; 75:101844. [PMID: 38237647 DOI: 10.1016/j.mito.2024.101844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Revised: 12/07/2023] [Accepted: 01/14/2024] [Indexed: 01/26/2024]
Abstract
Genomic investigations on an infant who presented with a putative mitochondrial disorder led to identification of compound heterozygous deletion with an overlapping region of ∼142 kb encompassing two nuclear encoded genes namely ERCC8 and NDUFAF2. Investigations on fetal-derived fibroblast culture demonstrated impaired bioenergetics and mitochondrial dysfunction, which explains the phenotype and observed infant mortality in the present study. The genetic findings from this study extended the utility of whole-genome sequencing as it led to development of a MLPA-based assay for carrier screening in the extended family and the prenatal testing aiding in the birth of two healthy children.
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Affiliation(s)
- Ankit Sabharwal
- CSIR Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India; Department of Pediatrics, Dell Medical School, The University of Texas at Austin, Austin, Texas, United States.
| | - Vishu Gupta
- CSIR Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Shamsudheen Kv
- CSIR Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | | | - Ankit Verma
- CSIR Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India
| | - Anushree Mishra
- Department of Pediatrics, All India Institute of Medical Sciences (AIIMS), Delhi, India
| | - Rahul C Bhoyar
- CSIR Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India
| | - Abhinav Jain
- CSIR Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Ambily Sivadas
- CSIR Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Sonali Rawat
- Stem Cell Facility, All India Institute of Medical Sciences (AIIMS), Delhi, India
| | - Bani Jolly
- CSIR Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Sujata Mohanty
- Stem Cell Facility, All India Institute of Medical Sciences (AIIMS), Delhi, India
| | - Sheffali Gulati
- Department of Pediatrics, All India Institute of Medical Sciences (AIIMS), Delhi, India
| | - Neerja Gupta
- Department of Pediatrics, All India Institute of Medical Sciences (AIIMS), Delhi, India
| | - Madhulika Kabra
- Department of Pediatrics, All India Institute of Medical Sciences (AIIMS), Delhi, India.
| | - Vinod Scaria
- CSIR Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India.
| | - Sridhar Sivasubbu
- CSIR Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India.
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Abu Hanna F, Zehavi Y, Cohen-Barak E, Khayat M, Warwar N, Shreter R, Rodenburg RJ, Spiegel R. Lack of mitochondrial complex I assembly factor NDUFAF2 results in a distinctive infantile-onset brainstem neurodegenerative disease with early lethality. Orphanet J Rare Dis 2024; 19:92. [PMID: 38419071 PMCID: PMC10900632 DOI: 10.1186/s13023-024-03094-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 02/21/2024] [Indexed: 03/02/2024] Open
Abstract
BACKGROUND Congenital disorders of the mitochondrial respiratory chain are a heterogeneous group of inborn errors of metabolism. Among them, NADH:ubiquinone oxidoreductase (complex I, CI) deficiency is the most common. Biallelic pathogenic variants in NDUFAF2, encoding the nuclear assembly CI factor NDUFAF2, were initially reported to cause progressive encephalopathy beginning in infancy. Since the initial report in 2005, less than a dozen patients with NDUFAF2-related disease have been reported. METHODS Clinical, biochemical, and neuroradiological features of four new patients residing in Northern Israel were collected during 2016-2022 at Emek Medical Center. Enzymatic activities of the five respiratory-chain complexes were determined in isolated fibroblast mitochondria by spectrophotometric methods. Western blot analyses were conducted with anti-human NDUFAF2 antibody; antibody against the mitochondrial marker VDAC1 was used as a loading control. Genetic studies were performed by chromosome microarray analysis using Affymetrix CytoScan 750 K arrays. RESULTS All four patients presented with infantile-onset growth retardation, ophthalmological impairments with nystagmus, strabismus (starting between 5 and 9 months), and further progressed to life-threatening episodes of apnea usually triggered by trivial febrile illnesses (between 10 and 18 months) with gradual loss of acquired developmental milestones (3 of 4 patients). Serial magnetic-resonance imaging studies in two of the four patients showed a progressive pattern of abnormal T2-weighted hyperintense signals involving primarily the brainstem, the upper cervical cord, and later, the basal ganglia and thalami. Magnetic-resonance spectroscopy in one patient showed an increased lactate peak. Disease progression was marked by ventilatory dependency and early lethality. 3 of the 4 patients tested, harbored a homozygous 142-kb partial interstitial deletion that omits exons 2-4 of NDUFAF2. Mitochondrial CI activity was significantly decreased in the only patient tested. Western blot analysis disclosed the absence of NDUFAF2 protein compared to normal controls. In addition, we reviewed all 10 previously reported NDUFAF2-deficient cases to better characterize the disease. CONCLUSIONS Biallelic loss-of-function mutations in NDUFAF2 result in a distinctive phenotype in the spectrum of Leigh syndrome with clinical and neuroradiological features that are primarily attributed to progressive brainstem damage.
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Affiliation(s)
- Firas Abu Hanna
- Department of Pediatrics B, Emek Medical Center, 1834111, Afula, Israel
- Rappaport School of Medicine, Technion, Haifa, Israel
| | - Yoav Zehavi
- Department of Pediatrics B, Emek Medical Center, 1834111, Afula, Israel
- Rappaport School of Medicine, Technion, Haifa, Israel
| | - Eran Cohen-Barak
- Rappaport School of Medicine, Technion, Haifa, Israel
- Department of Dermatology, Emek Medical Center, Afula, Israel
| | - Morad Khayat
- Emek Medical Center, Genetic Institute, Afula, Israel
| | - Nasim Warwar
- Emek Medical Center, Genetic Institute, Afula, Israel
| | - Roni Shreter
- Neuroradiology Unit, Hilel Yaffe Medical Center, Hadera, Israel
| | - Richard J Rodenburg
- Translational Metabolic Laboratory, Departments of Pediatrics and Genetics, Radboud UMC, Nijmegen, The Netherlands
| | - Ronen Spiegel
- Department of Pediatrics B, Emek Medical Center, 1834111, Afula, Israel.
- Rappaport School of Medicine, Technion, Haifa, Israel.
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Veluthakal R, Esparza D, Hoolachan JM, Balakrishnan R, Ahn M, Oh E, Jayasena CS, Thurmond DC. Mitochondrial Dysfunction, Oxidative Stress, and Inter-Organ Miscommunications in T2D Progression. Int J Mol Sci 2024; 25:1504. [PMID: 38338783 PMCID: PMC10855860 DOI: 10.3390/ijms25031504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 01/15/2024] [Accepted: 01/23/2024] [Indexed: 02/12/2024] Open
Abstract
Type 2 diabetes (T2D) is a heterogenous disease, and conventionally, peripheral insulin resistance (IR) was thought to precede islet β-cell dysfunction, promoting progression from prediabetes to T2D. New evidence suggests that T2D-lean individuals experience early β-cell dysfunction without significant IR. Regardless of the primary event (i.e., IR vs. β-cell dysfunction) that contributes to dysglycemia, significant early-onset oxidative damage and mitochondrial dysfunction in multiple metabolic tissues may be a driver of T2D onset and progression. Oxidative stress, defined as the generation of reactive oxygen species (ROS), is mediated by hyperglycemia alone or in combination with lipids. Physiological oxidative stress promotes inter-tissue communication, while pathological oxidative stress promotes inter-tissue mis-communication, and new evidence suggests that this is mediated via extracellular vesicles (EVs), including mitochondria containing EVs. Under metabolic-related stress conditions, EV-mediated cross-talk between β-cells and skeletal muscle likely trigger mitochondrial anomalies leading to prediabetes and T2D. This article reviews the underlying molecular mechanisms in ROS-related pathogenesis of prediabetes, including mitophagy and mitochondrial dynamics due to oxidative stress. Further, this review will describe the potential of various therapeutic avenues for attenuating oxidative damage, reversing prediabetes and preventing progression to T2D.
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Affiliation(s)
- Rajakrishnan Veluthakal
- Department of Molecular and Cellular Endocrinology, Arthur Riggs Diabetes & Metabolism Research Institute, City of Hope Beckman Research Institute, 1500 E. Duarte Rd, Duarte, CA 91010, USA; (D.E.); (J.M.H.); (R.B.); (M.A.); (E.O.); (C.S.J.)
| | | | | | | | | | | | | | - Debbie C. Thurmond
- Department of Molecular and Cellular Endocrinology, Arthur Riggs Diabetes & Metabolism Research Institute, City of Hope Beckman Research Institute, 1500 E. Duarte Rd, Duarte, CA 91010, USA; (D.E.); (J.M.H.); (R.B.); (M.A.); (E.O.); (C.S.J.)
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Ju Wang JD, Chen M, Zhang C, Parker J, Saneto R, Ramirez JM. Sleep and Breathing Disturbances in Children With Leigh Syndrome: A Comparative Study. Pediatr Neurol 2022; 136:56-63. [PMID: 36137349 DOI: 10.1016/j.pediatrneurol.2022.08.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 07/24/2022] [Accepted: 08/18/2022] [Indexed: 02/02/2023]
Abstract
BACKGROUND Leigh syndrome (LS) is a progressive neurodegenerative mitochondrial disease characterized by necrotizing lesions affecting different parts of the central nervous system, especially in the brainstem and basal ganglia. Lesions in this area may involve respiratory and sleep centers, resulting in the clinically significant disturbances seen-but poorly characterized-in LS. The purpose of the present study is to characterize and compare the physiologic responses to respiratory disturbances quantified by polysomnography metrics of children with LS with age-sex- and apnea-hypopnea index (AHI)-matched patients with obstructive sleep apnea (OSA), a common clinical population with similar burden of sleep-disordered breathing. METHODS Retrospective comparative study of polysomnographic data from six patients with LS were reviewed and compared with 18 age-sex-AHI-matched patients with OSA, with particular attention to cardiorespiratory and sleep architecture metrics. RESULTS Sleep architecture and stage duration were conserved in LS and OSA groups, but increased wake after sleep onset was seen among the first group. The LS group exhibited both obstructive and central sleep apnea. The group also had significantly greater values of heart rate, ≥3% oxygen desaturation index, and lower values of sleep efficiency, respiratory arousal index, and total sleep time when compared with the OSA group. CONCLUSIONS Patients with LS exhibited significantly more sleep-related cardiorespiratory disturbances and sleep fragmentation when compared with neurotypical children with OSA. Given that these findings are plausibly detrimental to health and development, sleep evaluation in patients with similar conditions should be encouraged for early management.
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Affiliation(s)
- Jia-Der Ju Wang
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington.
| | - Maida Chen
- Division of Pulmonary and Sleep Medicine, Department of Pediatrics, University of Washington School of Medicine, Seattle, Washington
| | | | - Jessica Parker
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
| | - Russell Saneto
- Division of Pediatric Neurology, Department of Neurology, University of Washington School of Medicine, Seattle, Washington
| | - Jan-Marino Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington; Departments of Neurological Surgery, University of Washington School of Medicine, Seattle, Washington; Departments of Pediatrics, University of Washington School of Medicine, Seattle, Washington
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Subrahmanian N, LaVoie MJ. Is there a special relationship between complex I activity and nigral neuronal loss in Parkinson's disease? A critical reappraisal. Brain Res 2021; 1767:147434. [PMID: 33745923 PMCID: PMC9520341 DOI: 10.1016/j.brainres.2021.147434] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 02/25/2021] [Accepted: 03/12/2021] [Indexed: 12/21/2022]
Abstract
Parkinson’s disease (PD) is a progressive neurodegenerative disease manifesting both motor and non-motor symptoms. The motor features are generally ascribed to the selective loss of dopamine neurons within the substantia nigra pars compacta. While the precise etiology of PD remains elusive, multiple genetic and environmental elements have emerged as contributing factors. The discovery of MPTP-induced parkinsonism directed intense inquiry towards mitochondrial pathways, with a specific focus on mitochondrial complex I. Consisting of more than 40 subunits, complex I is the first enzyme of the electron transport chain that is required for mitochondrial ATP production. In this review, we present a critical analysis of studies assessing the prevalence and specificity of mitochondrial complex I deficiency in PD. In addition, we take the novel view of incorporating the features of genetically-defined bona fide complex I disorders and the prevalence of nigral involvement in such cases. Through this innovative bi-directional view, we consider both complex I changes in a disease of the substantia nigra and nigral changes in diseases of complex I. We assess the strength of association between nigral cell loss and complex I deficits, as well as the oft under-appreciated heterogeneity of complex I deficiency disorders and the variability of the PD data.
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Affiliation(s)
- Nitya Subrahmanian
- Department of Neurology, University of Florida, Gainesville, FL 32610, USA
| | - Matthew J LaVoie
- Department of Neurology, University of Florida, Gainesville, FL 32610, USA.
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Deák F, Anderson RE, Fessler JL, Sherry DM. Novel Cellular Functions of Very Long Chain-Fatty Acids: Insight From ELOVL4 Mutations. Front Cell Neurosci 2019; 13:428. [PMID: 31616255 PMCID: PMC6763723 DOI: 10.3389/fncel.2019.00428] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 09/06/2019] [Indexed: 12/22/2022] Open
Abstract
Elongation of Very Long chain fatty acids-4 (ELOVL4) protein is a member of the ELOVL family of fatty acid elongases that is collectively responsible for catalyzing formation of long chain fatty acids. ELOVL4 is the only family member that catalyzes production of Very Long Chain Saturated Fatty Acids (VLC-SFA) and Very Long Chain Polyunsaturated Fatty Acids (VLC-PUFA) with chain lengths ≥28 carbons. ELOVL4 and its VLC-SFA and VLC-PUFA products are emerging as important regulators of synaptic signaling and neuronal survival in the central nervous system (CNS). Distinct sets of mutations in ELOVL4 cause three different neurological diseases in humans. Heterozygous inheritance of one set of autosomal dominant ELOVL4 mutations that leads to truncation of the ELOVL4 protein causes Stargardt-like macular dystrophy (STGD3), an aggressive juvenile-onset retinal degeneration. Heterozygous inheritance of a different set of autosomal dominant ELOVL4 mutations that leads to a full-length protein with single amino acid substitutions causes spinocerebellar ataxia 34 (SCA34), a late-onset neurodegenerative disease characterized by gait ataxia and cerebellar atrophy. Homozygous inheritance of a different set of ELOVL4 mutations causes a more severe disease with infantile onset characterized by seizures, spasticity, intellectual disability, ichthyosis, and premature death. ELOVL4 is expressed widely in the CNS and is found primarily in neurons. ELOVL4 is expressed in cell-specific patterns within different regions of the CNS that are likely to be related to disease symptoms. In the retina, ELOVL4 is expressed exclusively in photoreceptors and produces VLC-PUFA that are incorporated into phosphatidylcholine and enriched in the light sensitive membrane disks of the photoreceptor outer segments. VLC-PUFA are enzymatically converted into "elovanoid" compounds that appear to provide paracrine signals that promote photoreceptor and neuronal survival. In the brain, the main ELOVL4 products are VLC-SFA that are incorporated into sphingolipids and enriched in synaptic vesicles, where they regulate kinetics of presynaptic neurotransmitter release. Understanding the function of ELOVL4 and its VLC-SFA and VLC-PUFA products will advance our understanding of basic mechanisms in neural signaling and has potential for developing novel therapies for seizure and neurodegenerative diseases.
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Affiliation(s)
- Ferenc Deák
- Department of Geriatric Medicine, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Oklahoma Center for Neurosciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Harold Hamm Diabetes Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Robert E Anderson
- Department of Geriatric Medicine, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Oklahoma Center for Neurosciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Jennifer L Fessler
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - David M Sherry
- Oklahoma Center for Neurosciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Department of Pharmaceutical Sciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
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9
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Mohammadi-Asl J, Hajjari M, Tahmasebi Birgani M, Riahi K, Nasiri H, Kollaee A. Exome sequencing revealed a novel deletion in the ERCC8 gene in an Iranian family with Cockayne syndrome. Ann Hum Genet 2018; 82:304-308. [PMID: 30039856 DOI: 10.1111/ahg.12255] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 01/16/2018] [Accepted: 02/05/2018] [Indexed: 11/30/2022]
Abstract
Cockayne syndrome (CS) is one the rare DNA-repair deficiency disorders with autosomal recessive inheritance. Failure to thrive and microcephaly are the major criteria of diagnosis. Owing to genetic heterogeneity of CS, whole exome sequencing is promising way to determine the genetic basis of the disease. Here, we present c.1053delT in ERCC8 gene in an Iranian family with symptom of CS using whole exome sequencing. The deletion was novel and was not previously reported elsewhere.
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Affiliation(s)
- J Mohammadi-Asl
- Department of Medical Genetics, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.,Noor Genetics Lab, Ahvaz, Iran
| | - M Hajjari
- Department of Genetics, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran
| | - M Tahmasebi Birgani
- Department of Medical Genetics, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - K Riahi
- Research Center of Thalasemia and Hemoglobinopathy, Ahvaz Jundishapur university of Medical Sciences, Ahvaz, Iran.,Pediatric Department, Ahvaz Jundishapur University of Medical Sciences, Golestan Hospital, Golestan, Ahvaz, Iran
| | - H Nasiri
- Departement of Medical Genetics, Nika center of Health promotion and prevention Medicine, Tehran, Iran
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10
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Sailer A, Scholz SW, Nalls MA, Schulte C, Federoff M, Price TR, Lees A, Ross OA, Dickson DW, Mok K, Mencacci NE, Schottlaender L, Chelban V, Ling H, O'Sullivan SS, Wood NW, Traynor BJ, Ferrucci L, Federoff HJ, Mhyre TR, Morris HR, Deuschl G, Quinn N, Widner H, Albanese A, Infante J, Bhatia KP, Poewe W, Oertel W, Höglinger GU, Wüllner U, Goldwurm S, Pellecchia MT, Ferreira J, Tolosa E, Bloem BR, Rascol O, Meissner WG, Hardy JA, Revesz T, Holton JL, Gasser T, Wenning GK, Singleton AB, Houlden H. A genome-wide association study in multiple system atrophy. Neurology 2016; 87:1591-1598. [PMID: 27629089 PMCID: PMC5067544 DOI: 10.1212/wnl.0000000000003221] [Citation(s) in RCA: 105] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Accepted: 06/15/2016] [Indexed: 12/13/2022] Open
Abstract
OBJECTIVE To identify genetic variants that play a role in the pathogenesis of multiple system atrophy (MSA), we undertook a genome-wide association study (GWAS). METHODS We performed a GWAS with >5 million genotyped and imputed single nucleotide polymorphisms (SNPs) in 918 patients with MSA of European ancestry and 3,864 controls. MSA cases were collected from North American and European centers, one third of which were neuropathologically confirmed. RESULTS We found no significant loci after stringent multiple testing correction. A number of regions emerged as potentially interesting for follow-up at p < 1 × 10-6, including SNPs in the genes FBXO47, ELOVL7, EDN1, and MAPT. Contrary to previous reports, we found no association of the genes SNCA and COQ2 with MSA. CONCLUSIONS We present a GWAS in MSA. We have identified several potentially interesting gene loci, including the MAPT locus, whose significance will have to be evaluated in a larger sample set. Common genetic variation in SNCA and COQ2 does not seem to be associated with MSA. In the future, additional samples of well-characterized patients with MSA will need to be collected to perform a larger MSA GWAS, but this initial study forms the basis for these next steps.
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Affiliation(s)
- Anna Sailer
- Authors' affiliations are listed at the end of the article
| | - Sonja W Scholz
- Authors' affiliations are listed at the end of the article.
| | | | | | | | - T Ryan Price
- Authors' affiliations are listed at the end of the article
| | - Andrew Lees
- Authors' affiliations are listed at the end of the article
| | - Owen A Ross
- Authors' affiliations are listed at the end of the article
| | | | - Kin Mok
- Authors' affiliations are listed at the end of the article
| | | | | | | | - Helen Ling
- Authors' affiliations are listed at the end of the article
| | | | | | | | - Luigi Ferrucci
- Authors' affiliations are listed at the end of the article
| | | | | | - Huw R Morris
- Authors' affiliations are listed at the end of the article
| | | | - Niall Quinn
- Authors' affiliations are listed at the end of the article
| | - Hakan Widner
- Authors' affiliations are listed at the end of the article
| | | | - Jon Infante
- Authors' affiliations are listed at the end of the article
| | | | - Werner Poewe
- Authors' affiliations are listed at the end of the article
| | | | | | | | | | | | | | - Eduardo Tolosa
- Authors' affiliations are listed at the end of the article
| | | | - Olivier Rascol
- Authors' affiliations are listed at the end of the article
| | | | - John A Hardy
- Authors' affiliations are listed at the end of the article
| | - Tamas Revesz
- Authors' affiliations are listed at the end of the article
| | | | - Thomas Gasser
- Authors' affiliations are listed at the end of the article
| | | | | | - Henry Houlden
- Authors' affiliations are listed at the end of the article.
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11
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Giachin G, Bouverot R, Acajjaoui S, Pantalone S, Soler-López M. Dynamics of Human Mitochondrial Complex I Assembly: Implications for Neurodegenerative Diseases. Front Mol Biosci 2016; 3:43. [PMID: 27597947 PMCID: PMC4992684 DOI: 10.3389/fmolb.2016.00043] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 08/02/2016] [Indexed: 12/14/2022] Open
Abstract
Neurons are extremely energy demanding cells and highly dependent on the mitochondrial oxidative phosphorylation (OXPHOS) system. Mitochondria generate the energetic potential via the respiratory complexes I to IV, which constitute the electron transport chain (ETC), together with complex V. These redox reactions release energy in the form of ATP and also generate reactive oxygen species (ROS) that are involved in cell signaling but can eventually lead to oxidative stress. Complex I (CI or NADH:ubiquinone oxidoreductase) is the largest ETC enzyme, containing 44 subunits and the main contributor to ROS production. In recent years, the structure of the CI has become available and has provided new insights into CI assembly. A number of chaperones have been identified in the assembly and stability of the mature holo-CI, although they are not part of its final structure. Interestingly, CI dysfunction is the most common OXPHOS disorder in humans and defects in the CI assembly process are often observed. However, the dynamics of the events leading to CI biogenesis remain elusive, which precludes our understanding of how ETC malfunctioning affects neuronal integrity. Here, we review the current knowledge of the structural features of CI and its assembly factors and the potential role of CI misassembly in human disorders such as Complex I Deficiencies or Alzheimer's and Parkinson's diseases.
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Affiliation(s)
- Gabriele Giachin
- Structural Biology Group, European Synchrotron Radiation Facility Grenoble, France
| | - Romain Bouverot
- Structural Biology Group, European Synchrotron Radiation Facility Grenoble, France
| | - Samira Acajjaoui
- Structural Biology Group, European Synchrotron Radiation Facility Grenoble, France
| | - Serena Pantalone
- Structural Biology Group, European Synchrotron Radiation Facility Grenoble, France
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Sánchez-Caballero L, Guerrero-Castillo S, Nijtmans L. Unraveling the complexity of mitochondrial complex I assembly: A dynamic process. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:980-90. [PMID: 27040506 DOI: 10.1016/j.bbabio.2016.03.031] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 03/17/2016] [Accepted: 03/29/2016] [Indexed: 11/17/2022]
Abstract
Mammalian complex I is composed of 44 different subunits and its assembly requires at least 13 specific assembly factors. Proper function of the mitochondrial respiratory chain enzyme is of crucial importance for cell survival due to its major participation in energy production and cell signaling. Complex I assembly depends on the coordination of several crucial processes that need to be tightly interconnected and orchestrated by a number of assembly factors. The understanding of complex I assembly evolved from simple sequential concept to the more sophisticated modular assembly model describing a convoluted process. According to this model, the different modules assemble independently and associate afterwards with each other to form the final enzyme. In this review, we aim to unravel the complexity of complex I assembly and provide the latest insights in this fundamental and fascinating process. This article is part of a Special Issue entitled Respiratory complex I, edited by Volker Zickermann and Ulrich Brandt.
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Affiliation(s)
- Laura Sánchez-Caballero
- Radboud Center for Mitochondrial Medicine, Department of Pediatrics, Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525 GA Nijmegen, The Netherlands
| | - Sergio Guerrero-Castillo
- Radboud Center for Mitochondrial Medicine, Department of Pediatrics, Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525 GA Nijmegen, The Netherlands
| | - Leo Nijtmans
- Radboud Center for Mitochondrial Medicine, Department of Pediatrics, Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525 GA Nijmegen, The Netherlands
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13
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Szczałuba K, Nowakowska B, Sobecka K, Smyk M, Castaneda J, Klapecki J, Kutkowska-Kaźmierczak A, Śmigiel R, Bocian E, Radkowski M, Demkow U. Application of Array Comparative Genomic Hybridization in Newborns with Multiple Congenital Anomalies. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 912:1-9. [PMID: 26987320 DOI: 10.1007/5584_2016_235] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Major congenital anomalies are detectable in 2-3 % of the newborn population. Some of their genetic causes are attributable to copy number variations identified by array comparative genomic hybridization (aCGH). The value of aCGH screening as a first-tier test in children with multiple congenital anomalies has been studied and consensus adopted. However, array resolution has not been agreed upon, specifically in the newborn or infant population. Moreover, most array studies have been focused on mixed populations of intellectual disability/developmental delay with or without multiple congenital anomalies, making it difficult to assess the value of microarrays in newborns. The aim of the study was to determine the optimal quality and clinical sensitivity of high-resolution array comparative genomic hybridization in neonates with multiple congenital anomalies. We investigated a group of 54 newborns with multiple congenital anomalies defined as two or more birth defects from more than one organ system. Cytogenetic studies were performed using OGT CytoSure 8 × 60 K microarray. We found ten rearrangements in ten newborns. Of these, one recurrent syndromic microduplication was observed, whereas all other changes were unique. Six rearrangements were definitely pathogenic, including one submicroscopic and five that could be seen on routine karyotype analysis. Four other copy number variants were likely pathogenic. The candidate genes that may explain the phenotype were discussed. In conclusion, high-resolution array comparative hybridization can be applied successfully in newborns with multiple congenital anomalies as the method detects a significant number of pathogenic changes, resulting in early diagnoses. We hypothesize that small changes previously considered benign or even inherited rearrangements should be classified as potentially pathogenic at least until a subsequent clinical assessment would exclude a developmental delay or dysmorphism.
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Affiliation(s)
- Krzysztof Szczałuba
- Department of Medical Genetics, Institute of Mother and Child, 17a Kasprzaka St., 01-211, Warsaw, Poland.
| | - Beata Nowakowska
- Department of Medical Genetics, Institute of Mother and Child, 17a Kasprzaka St., 01-211, Warsaw, Poland
| | - Katarzyna Sobecka
- Department of Medical Genetics, Institute of Mother and Child, 17a Kasprzaka St., 01-211, Warsaw, Poland
| | - Marta Smyk
- Department of Medical Genetics, Institute of Mother and Child, 17a Kasprzaka St., 01-211, Warsaw, Poland
| | - Jennifer Castaneda
- Department of Medical Genetics, Institute of Mother and Child, 17a Kasprzaka St., 01-211, Warsaw, Poland
| | - Jakub Klapecki
- Department of Medical Genetics, Institute of Mother and Child, 17a Kasprzaka St., 01-211, Warsaw, Poland
| | - Anna Kutkowska-Kaźmierczak
- Department of Medical Genetics, Institute of Mother and Child, 17a Kasprzaka St., 01-211, Warsaw, Poland
| | - Robert Śmigiel
- Department of Genetics, Wroclaw Medical University, Wroclaw, Poland.,Department of Social Pediatrics, Wroclaw Medical University, Wroclaw, Poland
| | - Ewa Bocian
- Department of Medical Genetics, Institute of Mother and Child, 17a Kasprzaka St., 01-211, Warsaw, Poland
| | - Marek Radkowski
- Department of Immunopathology of Infectious and Parasitic Diseases, Warsaw Medical University, Warsaw, Poland
| | - Urszula Demkow
- Department of Laboratory Diagnostics and Clinical Immunology of Developmental Age, Warsaw Medical University, Warsaw, Poland
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Ting T, Brett M, Tan E, Shen Y, Lee S, Lim E, Vasanwala R, Lek N, Thomas T, Lim K, Tan E. Cockayne Syndrome due to a maternally-inherited whole gene deletion of ERCC8 and a paternally-inherited ERCC8 exon 4 deletion. Gene 2015. [DOI: 10.1016/j.gene.2015.07.065] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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15
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Cameron JM, MacKay N, Feigenbaum A, Tarnopolsky M, Blaser S, Robinson BH, Schulze A. Exome sequencing identifies complex I NDUFV2 mutations as a novel cause of Leigh syndrome. Eur J Paediatr Neurol 2015; 19:525-32. [PMID: 26008862 DOI: 10.1016/j.ejpn.2015.05.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Revised: 02/12/2015] [Accepted: 05/05/2015] [Indexed: 12/30/2022]
Abstract
BACKGROUND Two siblings with hypertrophic cardiomyopathy and brain atrophy were diagnosed with Complex I deficiency based on low enzyme activity in muscle and high lactate/pyruvate ratio in fibroblasts. METHODS Whole exome sequencing results of fibroblast gDNA from one sibling was narrowed down to 190 SNPs or In/Dels in 185 candidate genes by selecting non-synonymous coding sequence base pair changes that were not present in the SNP database. RESULTS Two compound heterozygous mutations were identified in both siblings in NDUFV2, encoding the 24 kDa subunit of Complex I. The intronic mutation (c.IVS2 + 1delGTAA) is disease causing and has been reported before. The other mutation is novel (c.669_670insG, p.Ser224Valfs*3) and predicted to cause a pathogenic frameshift in the protein. Subsequent investigation of 10 probands with complex I deficiency from different families revealed homozygosity for the intronic c.IVS2 + 1delGTAA mutation in a second, consanguineous family. In this family three of five siblings were affected. Interestingly, they presented with Leigh syndrome but no cardiac involvement. The same genotype had been reported previously in a two families but presenting with hypertrophic cardiomyopathy, trunk hypotonia and encephalopathy. CONCLUSION We have identified NDUFV2 mutations in two families with Complex I deficiency, including a novel mutation. The diagnosis of Leigh syndrome expands the clinical phenotypes associated with the c.IVS2 + 1delGTAA mutation in this gene.
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Affiliation(s)
- Jessie M Cameron
- Genetics & Genome Biology Program, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON M5G 0A4, Canada.
| | - Nevena MacKay
- Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada
| | - Annette Feigenbaum
- Division of Clinical and Metabolic Genetics, The Hospital for Sick Children and University of Toronto, Toronto, ON M5G 1X8, Canada.
| | - Mark Tarnopolsky
- Department of Pediatrics, McMaster University Medical Center, Hamilton, ON L8N 3Z5, Canada.
| | - Susan Blaser
- Department of Radiology, The Hospital for Sick Children and University of Toronto, ON M5G 1X8, Canada.
| | - Brian H Robinson
- Genetics & Genome Biology Program, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada.
| | - Andreas Schulze
- Genetics & Genome Biology Program, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Division of Clinical and Metabolic Genetics, The Hospital for Sick Children and University of Toronto, Toronto, ON M5G 1X8, Canada.
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16
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Purdy JG, Shenk T, Rabinowitz JD. Fatty acid elongase 7 catalyzes lipidome remodeling essential for human cytomegalovirus replication. Cell Rep 2015; 10:1375-85. [PMID: 25732827 PMCID: PMC4354725 DOI: 10.1016/j.celrep.2015.02.003] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Revised: 10/23/2014] [Accepted: 01/29/2015] [Indexed: 11/26/2022] Open
Abstract
Human cytomegalovirus (HCMV) infection rewires host cell metabolism, up-regulating flux from glucose into acetyl-CoA to feed fatty acid metabolism, with saturated very long-chain fatty acids (VLFCA) required for production of infectious virion progeny. The human genome encodes seven elongase enzymes (ELOVL) that extend long chain fatty acids into VLCFA. Here we identify ELOVL7 as pivotal for HCMV infection. HCMV induces ELOVL7 by more than 150-fold. This induction is dependent on mTOR and SREBP-1. ELOVL7 knockdown or mTOR inhibition impairs HCMV-induced fatty acid elongation, HCMV particle release, and infectivity per particle. ELOVL7 overexpression enhances HCMV replication. During HCMV infection, mTOR activity is maintained by the viral protein pUL38. Expression of pUL38 is sufficient to induce ELOVL7, and pUL38-deficient virus is partially defective in ELOVL7 induction and fatty acid elongation. Thus, through its ability to modulate mTOR and SREBP-1, HCMV induces ELOVL7 to synthesize the saturated VLCFA required for efficient virus replication.
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Affiliation(s)
- John G Purdy
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Thomas Shenk
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Joshua D Rabinowitz
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA; Department of Chemistry, Princeton University, Princeton, NJ 08544, USA.
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17
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Schlehe JS, Journel MSM, Taylor KP, Amodeo KD, LaVoie MJ. The mitochondrial disease associated protein Ndufaf2 is dispensable for Complex-1 assembly but critical for the regulation of oxidative stress. Neurobiol Dis 2013; 58:57-67. [PMID: 23702311 PMCID: PMC3748239 DOI: 10.1016/j.nbd.2013.05.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Revised: 05/03/2013] [Accepted: 05/10/2013] [Indexed: 02/03/2023] Open
Abstract
Deficiency in human mitochondrial Complex-1 has been linked to a wide variety of neurological disorders. Homozygous deletion of the Complex-1 associated protein, Ndufaf2, leads to a severe juvenile onset encephalopathy involving degeneration of the substantia nigra and other sub-cortical regions resulting in adolescent lethality. To understand the precise role of Ndufaf2 in Complex-1 function and its links to neurologic disease, we studied the effects on Complex-1 assembly and function, as well as pathological consequences at the cellular level, in multiple in vitro models of Ndufaf2 deficiency. Using both Ndufaf2-deficient human neuroblastoma cells and primary fibroblasts cultured from Ndufaf2 knock-out mice we found that Ndufaf2-deficiency selectively reduces Complex-1 activity. While Ndufaf2 is traditionally referred to as an assembly factor of Complex-1, surprisingly, however, Ndufaf2-deficient cells were able to assemble a fully mature Complex-1 enzyme, albeit with reduced kinetics. Importantly, no evidence of intermediate or incomplete assembly was observed. Ndufaf2 deficiency resulted in significant increases in oxidative stress and mitochondrial DNA deletion, consistent with contemporary hypotheses regarding the pathophysiology of inherited mutations in Complex-1 disorders. These data suggest that Ndufaf2, unlike other Complex-1 assembly factors, may be more accurately described as a chaperone involved in proper folding during Complex-1 assembly, since it is dispensable for Complex-1 maturation but not its proper function.
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Affiliation(s)
- Julia S Schlehe
- Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
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18
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Large copy number variations in combination with point mutations in the TYMP and SCO2 genes found in two patients with mitochondrial disorders. Eur J Hum Genet 2013; 22:431-4. [PMID: 23838601 DOI: 10.1038/ejhg.2013.148] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 05/21/2013] [Accepted: 05/27/2013] [Indexed: 11/09/2022] Open
Abstract
Mitochondrial disorders are caused by defects in mitochondrial or nuclear DNA. Although the existence of large deletions in mitochondrial DNA (mtDNA) is well known, deletions affecting whole genes are not commonly described in patients with mitochondrial disorders. Based on the results of whole-genome analyses, copy number variations (CNVs) occur frequently in the human genome and may overlap with many genes associated with clinical phenotypes. We report the discovery of two large heterozygous CNVs on 22q13.33 in two patients with mitochondrial disorders. The first patient harboured a novel point mutation c.667G>A (p.D223N) in the SCO2 gene in combination with a paternally inherited 87-kb deletion. As hypertrophic cardiomyopathy (HCMP) was not documented in the patient, this observation prompted us to compare his clinical features with all 44 reported SCO2 patients in the literature. Surprisingly, the review shows that HCMP was present in only about 50% of the SCO2 patients with non-neonatal onset. In the second patient, who had mitochondrial neurogastrointestinal encephalopathy (MNGIE), a maternally inherited 175-kb deletion and the paternally inherited point mutation c.261G>T (p.E87D) in the TYMP gene were identified.
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19
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Iommarini L, Calvaruso MA, Kurelac I, Gasparre G, Porcelli AM. Complex I impairment in mitochondrial diseases and cancer: Parallel roads leading to different outcomes. Int J Biochem Cell Biol 2013; 45:47-63. [DOI: 10.1016/j.biocel.2012.05.016] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 05/03/2012] [Accepted: 05/24/2012] [Indexed: 02/06/2023]
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Pagniez-Mammeri H, Rak M, Legrand A, Bénit P, Rustin P, Slama A. Mitochondrial complex I deficiency of nuclear origin II. Non-structural genes. Mol Genet Metab 2012; 105:173-9. [PMID: 22099533 DOI: 10.1016/j.ymgme.2011.10.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2011] [Revised: 10/07/2011] [Accepted: 10/07/2011] [Indexed: 12/01/2022]
Abstract
Complex I deficiency is the most frequent cause of respiratory chain diseases. This large multiprotein complex is composed in human of 45 structural subunits, of which 7 are mitochondrial-encoded and 38 are nuclear-encoded. Most of the pathological mutations responsible for complex I deficiencies have been identified to date in complex I structural subunits. Numerous studies from last decade gave some insight into the biogenesis of this huge multi subunit complex of double genetic origin. A sequential incorporation of the structural subunits as well as ten complex I assembly factors has been described. Here, we present a short overview of the human complex I biogenesis and we review the pathological mutations identified to date in eight of the ten known complex I assembly factors.
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Affiliation(s)
- Hélène Pagniez-Mammeri
- Laboratoire de Biochimie, APHP Hôpital de Bicêtre, 78 rue du Général Leclerc, 94275 Le Kremlin Bicêtre cedex, France
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Nouws J, Nijtmans LGJ, Smeitink JA, Vogel RO. Assembly factors as a new class of disease genes for mitochondrial complex I deficiency: cause, pathology and treatment options. Brain 2011; 135:12-22. [DOI: 10.1093/brain/awr261] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
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Abstract
Mitochondrial diseases involve the dysfunction of the oxidative phosphorylation (OXPHOS) system. This group of diseases presents with heterogeneous clinical symptoms affecting mainly organs with high energy demands. Defects in the multimeric complexes comprising the OXPHOS system have a dual genetic origin, mitochondrial or nuclear DNA. Although many nuclear DNA mutations involve genes coding for subunits of the respiratory complexes, the majority of mutations found to date affect factors that do not form part of the final complexes. These assembly factors or chaperones have multiple functions ranging from cofactor insertion to proper assembly/stability of the complexes. Although significant progress has been made in the last few years in the discovery of new assembly factors, the function of many remains elusive. Here, we describe assembly factors or chaperones that are required for respiratory chain complex assembly and their clinical relevance.
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23
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Ghai SJ, Shago M, Shroff M, Yoon G. Cockayne syndrome caused by paternally inherited 5 Mb deletion of 10q11.2 and a frameshift mutation of ERCC6. Eur J Med Genet 2011; 54:272-6. [PMID: 21376145 DOI: 10.1016/j.ejmg.2011.02.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Accepted: 02/16/2011] [Indexed: 10/18/2022]
Abstract
Cockayne syndrome is a rare multi-systemic autosomal recessive condition characterized by variable post natal growth failure, neurological impairment, feeding difficulty, and progressive skin, ophthalmological, auditory and dental abnormalities. Life-span is usually shortened and death occurs in childhood or adolescence in the majority of cases. Only 3 cases of chromosomal aberrations as a cause of CS have been previously reported. We report a patient with a clinical phenotype of severe infantile CS who has a paternally inherited 5 Mb deletion of 10q11.2 resulting in loss of one allele and a previously unreported frameshift mutation of ERCC6 on the maternal allele.
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Affiliation(s)
- Shailly Jain Ghai
- Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, ON M5G 1X8, Canada.
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Abstract
PURPOSE OF REVIEW Mitochondrial diseases are individually uncommon, but collectively pose a significant burden on human health. Primary mitochondrial disease is caused by defects in the mitochondrial DNA-encoded genes or in nuclear genes whose products are imported into the mitochondrion. Great strides have been made in determining the cause of mitochondrial disorders, but the clinical ability to diagnose these conditions lags behind because of phenotypic overlap between distinct genetic entities and the complexity and invasiveness of standard diagnostic testing. In this review, we evaluate new findings in mitochondrial genetics, recent developments in mitochondrial disease diagnostic testing, and emerging ideas for mitochondrial disease therapies. RECENT FINDINGS Clinical cohort studies have revealed important themes in patient care relative to manifestations of mitochondrial disease. Significant strides have also been made toward creating embryos free from the risk of maternally inherited mitochondrial DNA-based disease. Several new genetic causes of both nuclear and mitochondrial DNA-based diseases have been identified in the past year. In addition, novel insights have emerged from basic studies of mitochondrial biology that hold promise for the development of targeted mitochondrial disease therapies. SUMMARY Research on mitochondrial biology and disease continues to improve the clinical capacity to diagnose the heterogeneous group of mitochondrial diseases that afflict the pediatric population. This research also provides a framework for future approaches to devise effective mitochondrial disease therapies.
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26
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Fassone E, Duncan AJ, Taanman JW, Pagnamenta AT, Sadowski MI, Holand T, Qasim W, Rutland P, Calvo SE, Mootha VK, Bitner-Glindzicz M, Rahman S. FOXRED1, encoding an FAD-dependent oxidoreductase complex-I-specific molecular chaperone, is mutated in infantile-onset mitochondrial encephalopathy. Hum Mol Genet 2010; 19:4837-47. [PMID: 20858599 DOI: 10.1093/hmg/ddq414] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Complex I is the first and largest enzyme in the respiratory chain and is located in the inner mitochondrial membrane. Complex I deficiency is the most commonly reported mitochondrial disorder presenting in childhood, but the molecular basis of most cases remains elusive. We describe a patient with complex I deficiency caused by mutation of the molecular chaperone FOXRED1. A combined homozygosity mapping and bioinformatics approach in a consanguineous Iranian-Jewish pedigree led to the identification of a homozygous mutation in FOXRED1 in a child who presented with infantile-onset encephalomyopathy. Silencing of FOXRED1 in human fibroblasts resulted in reduced complex I steady-state levels and activity, while lentiviral-mediated FOXRED1 transgene expression rescued complex I deficiency in the patient fibroblasts. This FAD-dependent oxidoreductase, which has never previously been associated with human disease, is now shown to be a complex I-specific molecular chaperone. The discovery of the c.1054C>T; p.R352W mutation in the FOXRED1 gene is a further contribution towards resolving the complex puzzle of the genetic basis of human mitochondrial disease.
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Affiliation(s)
- Elisa Fassone
- Clinical and Molecular Genetics Unit, UCL Institute of Child Health, London WC1N 1EH, UK
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Guillou H, Zadravec D, Martin PGP, Jacobsson A. The key roles of elongases and desaturases in mammalian fatty acid metabolism: Insights from transgenic mice. Prog Lipid Res 2009; 49:186-99. [PMID: 20018209 DOI: 10.1016/j.plipres.2009.12.002] [Citation(s) in RCA: 569] [Impact Index Per Article: 37.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Revised: 12/09/2009] [Accepted: 12/10/2009] [Indexed: 12/31/2022]
Abstract
In mammalian cells, elongases and desaturases play critical roles in regulating the length and degree of unsaturation of fatty acids and thereby their functions and metabolic fates. In the past decade, a great deal has been learnt about these enzymes and the first part of this review summarizes our current knowledge concerning these enzymes. More recently, several transgenic mouse models lacking either an elongase (Elovl3(-/-), Elovl4(-/-), Elovl5(-/-), Elovl6(-/-)) or a desaturase (Scd-1(-/-), Scd-2(-/-), Fads2(-/-)) have been developed and the second part of this review focuses on the insights gained from studies with these mice, as well as from investigations on cell cultures.
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Affiliation(s)
- Hervé Guillou
- Integrative Toxicology and Metabolism, Pôle de Toxicologie Alimentaire, Laboratoire de Pharmacologie et Toxicologie, Institut National de la Recherche Agronomique INRA UR66, Toulouse Cedex 3, France
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