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Integrated SWATH-based and targeted-based proteomics provide insights into the retinal emmetropization process in guinea pig. J Proteomics 2018; 181:1-15. [PMID: 29572162 DOI: 10.1016/j.jprot.2018.03.023] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 03/12/2018] [Accepted: 03/19/2018] [Indexed: 01/13/2023]
Abstract
Myopia is generally regarded as a failure of normal emmetropization process, however, its underlying molecular mechanisms are unclear. To investigate the retinal protein profile changes during emmetropization, we studied differential protein expressions of ocular growth in young guinea pigs at 3 and 21 days old respectively, when significant axial elongation was detected (P < 0.001, n = 10). Independent pooled retinal samples of both eyes were subjected to SWATH mass spectrometry (MS) followed by bioinformatics analysis using cloud-based platforms. A comprehensive retina SWATH ion-library consisting of 3138 (22,871) unique proteins (peptides) at 1% FDR was constructed. 40 proteins were found to be significantly up-regulated and 8 proteins down-regulated during emmetropization (≥log2 of 0.43 with ≥2 peptides matched per protein; P < 0.05). Using pathway analysis, the most significant pathway identifiable was 'phototransduction' (P = 1.412e-4). Expression patterns of 7 proteins identified in this pathway were further validated and confirmed (P < 0.05) with high-resolution Multiple Reaction Monitoring (MRM-HR) MS. Combining discovery and targeted proteomics approaches, this study for the first time comprehensively profiled protein changes in the guinea pig retina during normal emmetropization-associated eye growth. The findings of this study are also relevant to the myopia development, which is the result of failed emmetropization. SIGNIFICANCE Myopia is considered as a failure of emmetropization. However, the underlying biochemical mechanism of emmetropization, a visually guided process in which eye grows towards the optimal optical state of clear vision during early development, is not well understood. Retina is known as the key tissue to regulate this active eye growth. we studied eye growth of young guinea pigs and harvested their retinal tissues. A comprehensive SWATH ion library with identification of a total 3138 unique proteins were established, in which 48 proteins exhibited significant differential expressions between 3 and 21 days old. After MRM-HR confirmation, 'phototransduction' were found as the most active pathway during emmetropic eye growth. This study is the first in discovering key retinal protein players and pathways which are presumably orchestrated by biological mechanism(s) underlying emmetropization.
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Couser NL, Marchuk DS, Smith LD, Arreola A, Kaiser-Rogers KA, Muenzer J, Pandya A, Gucsavas-Calikoglu M, Powell CM. Co-occurring Down syndrome and SUCLA2-related mitochondrial depletion syndrome. Am J Med Genet A 2017; 173:2720-2724. [PMID: 28749033 DOI: 10.1002/ajmg.a.38351] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 06/09/2017] [Accepted: 06/14/2017] [Indexed: 01/23/2023]
Abstract
Mitochondrial DNA depletion syndrome 5 (MIM 612073) is a rare autosomal recessive disorder caused by homozygous or compound heterozygous pathogenic variants in the beta subunit of the succinate-CoA ligase gene located within the 13q14 band. We describe two siblings of Hispanic descent with SUCLA2-related mitochondrial depletion syndrome (encephalomyopathic form with methylmalonic aciduria); the older sibling is additionally affected with trisomy 21. SUCLA2 sequencing identified homozygous p.Arg284Cys pathogenic variants in both patients. This mutation has previously been identified in four individuals of Italian and Caucasian descent. The older sibling with concomitant disease has a more severe phenotype than what is typically described in patients with either SUCLA2-related mitochondrial depletion syndrome or Down syndrome alone. The younger sibling, who has a normal female chromosome complement, is significantly less affected compared to her brother. While the clinical and molecular findings have been reported in about 50 patients affected with a deficiency of succinate-CoA ligase caused by pathogenic variants in SUCLA2, this report describes the first known individual affected with both a mitochondrial depletion syndrome and trisomy 21.
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Affiliation(s)
- Natario L Couser
- Department of Pediatrics, Division of Genetics and Metabolism, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.,Department of Ophthalmology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Daniel S Marchuk
- University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - Laurie D Smith
- Department of Pediatrics, Division of Genetics and Metabolism, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Alexandra Arreola
- Department of Pathology & Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Kathleen A Kaiser-Rogers
- Department of Pediatrics, Division of Genetics and Metabolism, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.,Department of Pathology & Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.,Department of Genetics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Joseph Muenzer
- Department of Pediatrics, Division of Genetics and Metabolism, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.,Department of Genetics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Arti Pandya
- Department of Pediatrics, Division of Genetics and Metabolism, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.,Department of Genetics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Muge Gucsavas-Calikoglu
- Department of Pediatrics, Division of Genetics and Metabolism, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Cynthia M Powell
- Department of Pediatrics, Division of Genetics and Metabolism, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.,Department of Genetics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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Güngör O, Özkaya AK, Güngör G, Karaer K, Dilber C, Aydin K. Novel mutation in SUCLA2 identified on sequencing analysis. Pediatr Int 2016; 58:659-61. [PMID: 26952923 DOI: 10.1111/ped.12921] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2015] [Revised: 12/01/2015] [Accepted: 01/12/2016] [Indexed: 11/26/2022]
Abstract
Succinate-CoA ligase, ADP-forming, beta subunit (SUCLA2)-related mitochondrial DNA depletion syndrome is caused by mutations affecting the ADP-using isoform of the beta subunit in succinyl-CoA synthase, which is involved in the Krebs cycle. The SUCLA2 protein is found mostly in heart, skeletal muscle, and brain tissues. SUCLA2 mutations result in a mitochondrial disorder that manifests as deafness, lesions in the basal ganglia, and encephalomyopathy accompanied by dystonia. Such mutations are generally associated with mildly increased plasma methylmalonic acid, increased plasma lactate, elevated plasma carnitine esters, and the presence of methylmalonic acid in urine. In this case report, we describe a new mutation in a patient with a succinyl-CoA synthase deficiency caused by an SUCLA2 defect.
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Affiliation(s)
- Olcay Güngör
- Department of Pediatric Neurology, Faculty of Medicine, Kahramanmaras Sutcu Imam University, Kahramanmaras, Turkey
| | - Ahmet Kağan Özkaya
- Department of Pediatric Emergency, Faculty of Medicine, Cukurova University, Adana, Turkey
| | - Gülay Güngör
- Department of Radiology, Necip Fazıl City Hospital, Kahramanmaras, Turkey
| | - Kadri Karaer
- Department of Medical Genetics, Dr Ersin Arslan State Hospital, Gaziantep, Turkey
| | - Cengiz Dilber
- Department of Pediatric Neurology, Faculty of Medicine, Kahramanmaras Sutcu Imam University, Kahramanmaras, Turkey
| | - Kürşad Aydin
- Department of Pediatric Neurology, Faculty of Medicine, Gazi University, Ankara, Turkey
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Chinopoulos C. The "B space" of mitochondrial phosphorylation. J Neurosci Res 2011; 89:1897-904. [PMID: 21541983 DOI: 10.1002/jnr.22659] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Revised: 02/09/2011] [Accepted: 03/10/2011] [Indexed: 11/07/2022]
Abstract
It was recently shown that, in progressively depolarizing mitochondria, the F(0) -F(1) ATP synthase and the adenine nucleotide translocase (ANT) may change directionality independently from each other (Chinopoulos et al. [2010] FASEB J. 24:2405). When the membrane potentials at which these two molecular entities reverse directionality, termed reversal potential (Erev), are plotted as a function of matrix ATP/ADP ratio, an area of the plot is bracketed by the Erev_ATPase and the Erev_ANT, which we call "B space". Both reversal potentials are dynamic, in that they depend on the fluctuating values of the participating reactants; however, Erev_ATPase is almost always more negative than Erev_ANT. Here we review the conditions that define the boundaries of the "B space". Emphasis is placed on the role of matrix substrate-level phosphorylation, because during metabolic compromise this mechanism could maintain mitochondrial membrane potential and prevent the influx of cytosolic ATP destined for hydrolysis by the reversed F(0) -F(1) ATP synthase.
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Valayannopoulos V, Haudry C, Serre V, Barth M, Boddaert N, Arnoux JB, Cormier-Daire V, Rio M, Rabier D, Vassault A, Munnich A, Bonnefont JP, de Lonlay P, Rötig A, Lebre AS. New SUCLG1 patients expanding the phenotypic spectrum of this rare cause of mild methylmalonic aciduria. Mitochondrion 2010; 10:335-41. [PMID: 20197121 DOI: 10.1016/j.mito.2010.02.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Revised: 01/20/2010] [Accepted: 02/22/2010] [Indexed: 10/19/2022]
Abstract
Deficiencies in two subunits of the succinyl-coenzyme A synthetase (SCS) have been involved in patients with encephalomyopathy and mild methylmalonic aciduria (MMA). In this study, we described three new SUCLG1 patients and performed a meta-analysis of the literature. Our report enlarges the phenotypic spectrum of SUCLG1 mutations and confirms that a characteristic metabolic profile (presence of MMA and C4-DC carnitine in urines) and basal ganglia MRI lesions are the hallmarks of SCS defects. As mitochondrial DNA depletion in muscle is not a constant finding in SUCLG1 patients, this may suggest that diagnosis should not be based on it, but also that alternative physiopathological mechanisms may be considered to explain the combined respiratory chain deficiency observed in SCS patients.
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Affiliation(s)
- Vassili Valayannopoulos
- Université Paris Descartes, Hôpital Necker-Enfants Malades et Inserm U781 et U797, Départements de Génétique, de Radiologie pédiatrique, des Maladies Métaboliques et de Biochimie B, Paris F-75015, France
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Mitochondrial DNA depletion syndrome due to mutations in the RRM2B gene. Neuromuscul Disord 2008; 18:453-9. [PMID: 18504129 DOI: 10.1016/j.nmd.2008.04.006] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2008] [Revised: 03/25/2008] [Accepted: 04/02/2008] [Indexed: 11/23/2022]
Abstract
Mitochondrial DNA depletion syndrome (MDS) is characterized by a reduction in mtDNA copy number and has been associated with mutations in eight nuclear genes, including enzymes involved in mitochondrial nucleotide metabolism (POLG, TK2, DGUOK, SUCLA2, SUCLG1, PEO1) and MPV17. Recently, mutations in the RRM2B gene, encoding the p53-controlled ribonucleotide reductase subunit, have been described in seven infants from four families, who presented with various combinations of hypotonia, tubulopathy, seizures, respiratory distress, diarrhea, and lactic acidosis. All children died before 4 months of age. We sequenced the RRM2B gene in three unrelated cases with unexplained severe mtDNA depletion. The first patient developed intractable diarrhea, profound weakness, respiratory distress, and died at 3 months. The other two unrelated patients had a much milder phenotype and are still alive at ages 27 and 36 months. All three patients had lactic acidosis and severe depletion of mtDNA in muscle. Muscle histochemistry showed RRF and COX deficiency. Sequencing the RRM2B gene revealed three missense mutations and two single nucleotide deletions in exons 6, 8, and 9, confirming that RRM2B mutations are important causes of MDS and that the clinical phenotype is heterogeneous and not invariably fatal in infancy.
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