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Pontoizeau C, Gaborit C, Tual N, Simon-Sola M, Rotaru I, Benoist M, Colella P, Lamazière A, Brassier A, Arnoux JB, Rötig A, Ottolenghi C, de Lonlay P, Mingozzi F, Cavazzana M, Schiff M. Successful treatment of severe MSUD in Bckdhb -/- mice with neonatal AAV gene therapy. J Inherit Metab Dis 2024; 47:41-49. [PMID: 36880392 DOI: 10.1002/jimd.12604] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 02/11/2023] [Accepted: 03/02/2023] [Indexed: 03/08/2023]
Abstract
Maple syrup urine disease (MSUD) is rare autosomal recessive metabolic disorder caused by the dysfunction of the mitochondrial branched-chain 2-ketoacid dehydrogenase (BCKD) enzyme complex leading to massive accumulation of branched-chain amino acids and 2-keto acids. MSUD management, based on a life-long strict protein restriction with nontoxic amino acids oral supplementation represents an unmet need as it is associated with a poor quality of life, and does not fully protect from acute life-threatening decompensations or long-term neuropsychiatric complications. Orthotopic liver transplantation is a beneficial therapeutic option, which shows that restoration of only a fraction of whole-body BCKD enzyme activity is therapeutic. MSUD is thus an ideal target for gene therapy. We and others have tested AAV gene therapy in mice for two of the three genes involved in MSUD, BCKDHA and DBT. In this study, we developed a similar approach for the third MSUD gene, BCKDHB. We performed the first characterization of a Bckdhb-/- mouse model, which recapitulates the severe human phenotype of MSUD with early-neonatal symptoms leading to death during the first week of life with massive accumulation of MSUD biomarkers. Based on our previous experience in Bckdha-/- mice, we designed a transgene carrying the human BCKDHB gene under the control of a ubiquitous EF1α promoter, encapsidated in an AAV8 capsid. Injection in neonatal Bckdhb-/- mice at 1014 vg/kg achieved long-term rescue of the severe MSUD phenotype of Bckdhb-/- mice. These data further validate the efficacy of gene therapy for MSUD opening perspectives towards clinical translation.
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Affiliation(s)
- Clément Pontoizeau
- Necker Hospital, APHP, Biochemistry, Metabolomics Unit, University Paris Cité, Paris, France
- Necker Hospital, APHP, Reference Center for Inborn Error of Metabolism, Pediatrics Department, University Paris Cité, Paris, France
- Inserm UMR_S1163, Institut Imagine, Paris, France
| | | | - Nolan Tual
- Inserm UMR_S1163, Institut Imagine, Paris, France
| | | | - Irina Rotaru
- Inserm UMR_S1163, Institut Imagine, Paris, France
| | | | | | | | - Anaïs Brassier
- Necker Hospital, APHP, Reference Center for Inborn Error of Metabolism, Pediatrics Department, University Paris Cité, Paris, France
| | - Jean-Baptiste Arnoux
- Necker Hospital, APHP, Reference Center for Inborn Error of Metabolism, Pediatrics Department, University Paris Cité, Paris, France
| | - Agnès Rötig
- Inserm UMR_S1163, Institut Imagine, Paris, France
| | - Chris Ottolenghi
- Necker Hospital, APHP, Biochemistry, Metabolomics Unit, University Paris Cité, Paris, France
- Necker Hospital, APHP, Reference Center for Inborn Error of Metabolism, Pediatrics Department, University Paris Cité, Paris, France
- Inserm UMR_S1163, Institut Imagine, Paris, France
| | - Pascale de Lonlay
- Necker Hospital, APHP, Reference Center for Inborn Error of Metabolism, Pediatrics Department, University Paris Cité, Paris, France
- Inserm U1151, Institut Necker Enfants Malades, Paris, France
| | | | - Marina Cavazzana
- Inserm UMR_S1163, Institut Imagine, Paris, France
- Necker Hospital, APHP, Biotherapies Department and Clinical Investigation Center, Inserm, University Paris Cité, Paris, France
| | - Manuel Schiff
- Necker Hospital, APHP, Reference Center for Inborn Error of Metabolism, Pediatrics Department, University Paris Cité, Paris, France
- Inserm UMR_S1163, Institut Imagine, Paris, France
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2
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Lv K, Cao X, Pedroso MM, Wu B, Li J, He B, Schenk G. Structure-guided engineering of branched-chain α-keto acid decarboxylase for improved 1,2,4-butanetriol production by in vitro synthetic enzymatic biosystem. Int J Biol Macromol 2024; 255:128303. [PMID: 37992939 DOI: 10.1016/j.ijbiomac.2023.128303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 11/07/2023] [Accepted: 11/19/2023] [Indexed: 11/24/2023]
Abstract
Efficient synthetic routes for biomanufacturing chemicals often require the overcoming of pathway bottlenecks by tailoring enzymes to improve the catalytic efficiency or even implement non-native activities. 1,2,4-butanetriol (BTO), a valuable commodity chemical, is currently biosynthesized from D-xylose via a four-enzyme reaction cascade, with the ThDP-dependent α-keto acid decarboxylase (KdcA) identified as the potential bottleneck. Here, to further enhance the catalytic activity of KdcA toward the non-native substrate α-keto-3-deoxy-xylonate (KDX), in silico screening and structure-guided evolution were performed. The best mutants, S286L/G402P and V461K, exhibited a 1.8- and 2.5-fold higher enzymatic activity in the conversion of KDX to 3,4-dihydroxybutanal when compared to KdcA, respectively. MD simulations revealed that the two sets of mutations reshaped the substrate binding pocket, thereby increasing the binding affinity for KDX and promoting interactions between KDX and cofactor ThDP. Then, when the V461K mutant instead of wild type KdcA was integrated into the enzyme cascade, a 1.9-fold increase in BTO titer was observed. After optimization of the reaction conditions, the enzyme cocktail contained V461K converted 60 g/L D-xylose to 22.1 g/L BTO with a yield of 52.1 %. This work illustrated that protein engineering is a powerful tool for modifying the output of metabolic pathway.
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Affiliation(s)
- Kemin Lv
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, China
| | - Xuefei Cao
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, China
| | - Marcelo Monteiro Pedroso
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Brisbane, Australia
| | - Bin Wu
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, China.
| | - Jiahuang Li
- School of Biopharmacy, China Pharmaceutical University, Nanjing, China.
| | - Bingfang He
- School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing, China
| | - Gerhard Schenk
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Brisbane, Australia
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3
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Ozcelik F, Arslan S, Ozguc Caliskan B, Kardas F, Ozkul Y, Dundar M. PPM1K defects cause mild maple syrup urine disease: The second case in the literature. Am J Med Genet A 2023; 191:1360-1365. [PMID: 36706222 DOI: 10.1002/ajmg.a.63129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Revised: 01/11/2023] [Accepted: 01/13/2023] [Indexed: 01/29/2023]
Abstract
Maple syrup urine disease (MSUD) is an inborn error of metabolism caused by the insufficient catabolism of branched-chain amino acids. BCKDHA, BCKDHB, DBT, and DLD encode the subunits of the branched-chain α-ketoacid dehydrogenase complex, which is responsible for the catabolism of these amino acids. Biallelic pathogenic variants in BCKDHA, BCKDHB, or DBT are characteristic of MSUD. In addition, a patient with a PPM1K defect was previously reported. PPM1K dephosphorylates and activates the enzyme complex. We report a patient with MSUD with mild findings and elevated BCAA levels carrying a novel homozygous start-loss variant in PPM1K. Our study offers further evidence that PPM1K variants cause mild MSUD.
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Affiliation(s)
- Firat Ozcelik
- Department of Medical Genetics, Erciyes University, Kayseri, Turkey
| | - Sezai Arslan
- Division of Nutrition and Metabolism, Department of Pediatrics, Erciyes University, Kayseri, Turkey
| | | | - Fatih Kardas
- Division of Nutrition and Metabolism, Department of Pediatrics, Erciyes University, Kayseri, Turkey
| | - Yusuf Ozkul
- Department of Medical Genetics, Erciyes University, Kayseri, Turkey
| | - Munis Dundar
- Department of Medical Genetics, Erciyes University, Kayseri, Turkey
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Billington CJ, Chapman KA, Leon E, Meltzer BW, Berger SI, Olson M, Figler RA, Hoang SA, Wanxing C, Wamhoff BR, Collado MS, Cusmano‐Ozog K. Genomic and biochemical analysis of repeatedly observed variants in DBT in individuals with maple syrup urine disease of Central American ancestry. Am J Med Genet A 2022; 188:2738-2749. [PMID: 35799415 PMCID: PMC9542135 DOI: 10.1002/ajmg.a.62893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 05/17/2022] [Accepted: 05/20/2022] [Indexed: 01/25/2023]
Abstract
Maple syrup urine disease (MSUD) is an intoxication-type inherited metabolic disorder in which hyperleucinemia leads to brain swelling and death without treatment. MSUD is caused by branched-chain alpha-ketoacid dehydrogenase deficiency due to biallelic loss of the protein products from the genes BCKDHA, BCKDHB, or DBT, while a distinct but related condition is caused by loss of DLD. In this case series, eleven individuals with MSUD caused by two pathogenic variants in DBT are presented. All eleven individuals have a deletion of exon 2 (delEx2, NM_001918.3:c.48_171del); six individuals are homozygous and five individuals are compound heterozygous with a novel missense variant (NM_001918.5:c.916 T > C [p.Ser306Pro]) confirmed to be in trans. Western Blot indicates decreased amount of protein product in delEx2;c.916 T > C liver cells and absence of protein product in delEx2 homozygous hepatocytes. Ultrahigh performance liquid chromatography-tandem mass spectrometry demonstrates an accumulation of branched-chain amino acids and alpha-ketoacids in explanted hepatocytes. Individuals with these variants have a neonatal-onset, non-thiamine-responsive, classical form of MSUD. Strikingly, the entire cohort is derived from families who immigrated to the Washington, DC, metro area from Honduras or El Salvador suggesting the possibility of a founder effect.
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Affiliation(s)
- Charles J. Billington
- Children's National Rare Disease InstituteWashingtonDistrict of ColumbiaUSA
- Department of PediatricsUniversity of MinnesotaMinneapolisMinnesotaUSA
| | | | - Eyby Leon
- Children's National Rare Disease InstituteWashingtonDistrict of ColumbiaUSA
| | - Beatrix W. Meltzer
- Laboratory Medicine, Children's National HospitalWashingtonDistrict of ColumbiaUSA
| | - Seth I. Berger
- Children's National Rare Disease InstituteWashingtonDistrict of ColumbiaUSA
| | - Matthew Olson
- HemoShear Therapeutics, Inc.CharlottesvilleVirginiaUSA
| | | | | | - Cui Wanxing
- Georgetown University HospitalWashingtonDistrict of ColumbiaUSA
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Boemer F, Josse C, Luis G, Di Valentin E, Thiry J, Cello C, Caberg JH, Dadoumont C, Harvengt J, Lumaka A, Bours V, Debray FG. Novel Loss of Function Variant in BCKDK Causes a Treatable Developmental and Epileptic Encephalopathy. Int J Mol Sci 2022; 23:ijms23042253. [PMID: 35216372 PMCID: PMC8878489 DOI: 10.3390/ijms23042253] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 02/10/2022] [Accepted: 02/16/2022] [Indexed: 12/19/2022] Open
Abstract
Branched-chain amino acids (BCAA) are essential amino acids playing crucial roles in protein synthesis and brain neurotransmission. Branched-chain ketoacid dehydrogenase (BCKDH), the flux-generating step of BCAA catabolism, is tightly regulated by reversible phosphorylation of its E1α-subunit. BCKDK is the kinase responsible for the phosphorylation-mediated inactivation of BCKDH. In three siblings with severe developmental delays, microcephaly, autism spectrum disorder and epileptic encephalopathy, we identified a new homozygous in-frame deletion (c.999_1001delCAC; p.Thr334del) of BCKDK. Plasma and cerebrospinal fluid concentrations of BCAA were markedly reduced. Hyperactivity of BCKDH and over-consumption of BCAA were demonstrated by functional tests in cells transfected with the mutant BCKDK. Treatment with pharmacological doses of BCAA allowed the restoring of BCAA concentrations and greatly improved seizure control. Behavioral and developmental skills of the patients improved to a lesser extent. Importantly, a retrospective review of the newborn screening results allowed the identification of a strong decrease in BCAA concentrations on dried blood spots, suggesting that BCKDK is a new treatable metabolic disorder probably amenable to newborn screening programs.
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Affiliation(s)
- François Boemer
- Biochemical Genetics Laboratory, Department of Human Genetics, CHU of Liege, University of Liege, 4000 Liege, Belgium; (G.L.); (C.C.)
- Correspondence: ; Tel.: +32-4-366-76-96; Fax: +32-4-366-84-74
| | - Claire Josse
- Department of Medical Oncology, CHU of Liege, University of Liege, 4000 Liege, Belgium; (C.J.); (J.T.)
- Laboratory of Human Genetics, Department of Biomedical and Preclinical Sciences, Groupe Interdisciplinaire de Génoprotéomique Appliquée-Recherche (GIGA-R), University of Liege, 4000 Liege, Belgium;
| | - Géraldine Luis
- Biochemical Genetics Laboratory, Department of Human Genetics, CHU of Liege, University of Liege, 4000 Liege, Belgium; (G.L.); (C.C.)
| | - Emmanuel Di Valentin
- Viral Vector Platform, Groupe Interdisciplinaire de Génoprotéomique Appliquée-Recherche (GIGA-R), University of Liege, 4000 Liege, Belgium;
| | - Jérôme Thiry
- Department of Medical Oncology, CHU of Liege, University of Liege, 4000 Liege, Belgium; (C.J.); (J.T.)
| | - Christophe Cello
- Biochemical Genetics Laboratory, Department of Human Genetics, CHU of Liege, University of Liege, 4000 Liege, Belgium; (G.L.); (C.C.)
| | - Jean-Hubert Caberg
- Molecular Genetics Laboratory, Department of Human Genetics, CHU of Liege, University of Liege, 4000 Liege, Belgium;
| | | | - Julie Harvengt
- Center of Genetics, Department of Human Genetics, CHU of Liege, University of Liege, 4000 Liege, Belgium; (J.H.); (V.B.)
| | - Aimé Lumaka
- Laboratory of Human Genetics, Department of Biomedical and Preclinical Sciences, Groupe Interdisciplinaire de Génoprotéomique Appliquée-Recherche (GIGA-R), University of Liege, 4000 Liege, Belgium;
| | - Vincent Bours
- Center of Genetics, Department of Human Genetics, CHU of Liege, University of Liege, 4000 Liege, Belgium; (J.H.); (V.B.)
| | - François-Guillaume Debray
- Metabolic Unit, Department of Human Genetics, CHU of Liege, University of Liege, 4000 Liege, Belgium;
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Vargas-Morales JM, Guizar-Heredia R, Méndez-García AL, Palacios-Gonzalez B, Schcolnik-Cabrera A, Granados O, López-Barradas AM, Vázquez-Manjarrez N, Medina-Vera I, Aguilar-López M, Tovar-Palacio C, Ordaz-Nava G, Rocha-Viggiano AK, Medina-Cerda E, Torres N, Ordovas JM, Tovar AR, Guevara-Cruz M, Noriega LG. Association of BCAT2 and BCKDH polymorphisms with clinical, anthropometric and biochemical parameters in young adults. Nutr Metab Cardiovasc Dis 2021; 31:3210-3218. [PMID: 34511290 DOI: 10.1016/j.numecd.2021.07.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Revised: 06/26/2021] [Accepted: 07/13/2021] [Indexed: 12/25/2022]
Abstract
BACKGROUND AND AIM Circulating amino acids are modified by sex, body mass index (BMI) and insulin resistance (IR). However, whether the presence of genetic variants in branched-chain amino acid (BCAA) catabolic enzymes modifies circulating amino acids is still unknown. Thus, we determined the frequency of two genetic variants, one in the branched-chain aminotransferase 2 (BCAT2) gene (rs11548193), and one in the branched-chain ketoacid dehydrogenase (BCKDH) gene (rs45500792), and elucidated their impact on circulating amino acid levels together with clinical, anthropometric and biochemical parameters. METHODS AND RESULTS We performed a cross-sectional comparative study in which we recruited 1612 young adults (749 women and 863 men) aged 19.7 ± 2.1 years and with a BMI of 24.9 ± 4.7 kg/m2. Participants underwent clinical evaluation and provided blood samples for DNA extraction and biochemical analysis. The single nucleotide polymorphisms (SNPs) were determined by allelic discrimination using real-time polymerase chain reaction (PCR). The frequencies of the less common alleles were 15.2 % for BCAT2 and 9.83 % for BCKDH. The subjects with either the BCAT2 or BCKDH SNPs displayed no differences in the evaluated parameters compared with subjects homozygotes for the most common allele at each SNP. However, subjects with both SNPs had higher body weight, BMI, blood pressure, glucose, and circulating levels of aspartate, isoleucine, methionine, and proline than the subjects homozygotes for the most common allele (P < 0.05, One-way ANOVA). CONCLUSION Our findings suggest that the joint presence of both the BCAT2 rs11548193 and BCKDH rs45500792 SNPs induces metabolic alterations that are not observed in subjects without either SNP.
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Affiliation(s)
- Juan M Vargas-Morales
- Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico
| | | | - Ana L Méndez-García
- Departamento de Fisiología de la Nutrición, Mexico; Facultad de Enfermería, Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico
| | | | - Alejandro Schcolnik-Cabrera
- Département de Biochimie et Médecine Moléculaire, Université de Montréal, Montréal, QC, Canada; Maisonneuve-Rosemont Hospital Research Centre, Montréal, QC, Canada
| | | | | | | | | | | | - Claudia Tovar-Palacio
- División de Nutrición, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Ciudad de México, Mexico
| | | | | | - Eduardo Medina-Cerda
- Centro de Salud Universitario, Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico
| | - Nimbe Torres
- Departamento de Fisiología de la Nutrición, Mexico
| | - José M Ordovas
- Nutrition and Genomics Laboratory, JM-USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA, USA; IMDEA Food Institute, CEI UAM + CSIC, Madrid, Spain
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Fang X, Zhu X, Feng Y, Bai Y, Zhao X, Liu N, Kong X. Genetic analysis by targeted next-generation sequencing and novel variation identification of maple syrup urine disease in Chinese Han population. Sci Rep 2021; 11:18939. [PMID: 34556729 PMCID: PMC8460745 DOI: 10.1038/s41598-021-98357-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 09/07/2021] [Indexed: 11/25/2022] Open
Abstract
Maple syrup urine disease (MSUD) is a rare autosomal recessive disorder that affects the degradation of branched chain amino acids (BCAAs). Only a few cases of MSUD have been documented in Mainland China. In this report, 8 patients (4 females and 4 males) with MSUD from 8 unrelated Chinese Han families were diagnosed at the age of 6 days to 4 months. All the coding regions and exon/intron boundaries of BCKDHA, BCDKHB, DBT and DLD genes were analyzed by targeted NGS in the 8 MSUD pedigrees. Targeted NGS revealed 2 pedigrees with MSUD Ia, 5 pedigrees with Ib, 1 pedigree with MSUD II. Totally, 13 variants were detected, including 2 variants (p.Ala216Val and p.Gly281Arg) in BCKDHA gene, 10 variants (p.Gly95Ala, p.Ser171Pro, p.Phe175Leu, p.Arg183Trp, p.Lys222Thr, p.Arg285Ter, p.Arg111Ter, p.S184Pfs*46, p.Arg170Cys, p.I160Ffs*25) in BCKDHB gene, 1 variant (p.Arg431Ter) in DBT gene. In addition, 4 previously unidentified variants (p.Gly281Arg in BCKDHA gene, p.Ser171Pro, p.Gly95Ala and p.Lys222Thr in BCKDHB gene) were identified. NGS plus Sanger sequencing detection is effective and accurate for gene diagnosis. Computational structural modeling indicated that these novel variations probably affect structural stability and considered as likely pathogenic variants.
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Affiliation(s)
- Xiaohua Fang
- Obstetrics and Gynecology Department, Genetics and Prenatal Diagnosis Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, People's Republic of China
| | - Xiaofan Zhu
- Obstetrics and Gynecology Department, Genetics and Prenatal Diagnosis Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, People's Republic of China
| | - Yin Feng
- Obstetrics and Gynecology Department, Genetics and Prenatal Diagnosis Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, People's Republic of China
| | - Ying Bai
- Obstetrics and Gynecology Department, Genetics and Prenatal Diagnosis Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, People's Republic of China
| | - Xuechao Zhao
- Obstetrics and Gynecology Department, Genetics and Prenatal Diagnosis Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, People's Republic of China
| | - Ning Liu
- Obstetrics and Gynecology Department, Genetics and Prenatal Diagnosis Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, People's Republic of China.
| | - Xiangdong Kong
- Obstetrics and Gynecology Department, Genetics and Prenatal Diagnosis Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, People's Republic of China.
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8
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Mann G, Adegoke OAJ. Effects of ketoisocaproic acid and inflammation on glucose transport in muscle cells. Physiol Rep 2021; 9:e14673. [PMID: 33400857 PMCID: PMC7785050 DOI: 10.14814/phy2.14673] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 10/28/2020] [Accepted: 10/28/2020] [Indexed: 01/01/2023] Open
Abstract
Branched-chain amino acids (BCAAs) are regulators of protein metabolism. However, elevated levels of BCAAs and their metabolites are linked to insulin resistance. We previously demonstrated that the leucine metabolite, α-ketoisocaproate (KIC), inhibited insulin-stimulated glucose transport in myotubes. Like KIC, inflammatory factors are implicated in the development of insulin resistance. Here, we analyzed the effect of KIC and inflammatory factors (homocysteine [50 μM], TNF-α [10 ng/ml], and interleukin 6 (IL-6) [10 ng/ml]) on myotubes. Although KIC suppressed insulin-stimulated glucose transport, addition of the inflammatory factors did not worsen this effect. Depletion of branched-chain aminotransferase 2, the enzyme that catalyzes the conversion of leucine into KIC, abrogated the effect of KIC and the inflammatory factors. The effect of insulin on AKTS473 and S6K1T389 phosphorylation was not modified by treatments. There were no treatment effects on glycogen synthase phosphorylation. Depletion of E1α subunit of branched-chain α-keto acid dehydrogenase, the enzyme that catalyzes the oxidative decarboxylation of KIC, suppressed insulin-stimulated glucose transport, especially in cells incubated in KIC. Thus, defects in BCAA catabolism are contributory to insulin resistance of glucose transport in myotubes, especially in the presence of KIC. Interventions that increase BCAA catabolism may promote muscle glucose utilization and improve insulin resistance and its sequelae.
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Affiliation(s)
- Gagandeep Mann
- Kinesiology and Health Science and Muscle Health Research CentreYork UniversityTorontoONCanada
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9
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Strauss KA, Carson VJ, Soltys K, Young ME, Bowser LE, Puffenberger EG, Brigatti KW, Williams KB, Robinson DL, Hendrickson C, Beiler K, Taylor CM, Haas-Givler B, Chopko S, Hailey J, Muelly ER, Shellmer DA, Radcliff Z, Rodrigues A, Loeven K, Heaps AD, Mazariegos GV, Morton DH. Branched-chain α-ketoacid dehydrogenase deficiency (maple syrup urine disease): Treatment, biomarkers, and outcomes. Mol Genet Metab 2020; 129:193-206. [PMID: 31980395 DOI: 10.1016/j.ymgme.2020.01.006] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 01/11/2020] [Accepted: 01/13/2020] [Indexed: 12/26/2022]
Abstract
Over the past three decades, we studied 184 individuals with 174 different molecular variants of branched-chain α-ketoacid dehydrogenase activity, and here delineate essential clinical and biochemical aspects of the maple syrup urine disease (MSUD) phenotype. We collected data about treatment, survival, hospitalization, metabolic control, and liver transplantation from patients with classic (i.e., severe; n = 176), intermediate (n = 6) and intermittent (n = 2) forms of MSUD. A total of 13,589 amino acid profiles were used to analyze leucine tolerance, amino acid homeostasis, estimated cerebral amino acid uptake, quantitative responses to anabolic therapy, and metabolic control after liver transplantation. Standard instruments were used to measure neuropsychiatric outcomes. Despite advances in clinical care, classic MSUD remains a morbid and potentially fatal disorder. Stringent dietary therapy maintains metabolic variables within acceptable limits but is challenging to implement, fails to restore appropriate concentration relationships among circulating amino acids, and does not fully prevent cognitive and psychiatric disabilities. Liver transplantation eliminates the need for a prescription diet and safeguards patients from life-threatening metabolic crises, but is associated with predictable morbidities and does not reverse pre-existing neurological sequelae. There is a critical unmet need for safe and effective disease-modifying therapies for MSUD which can be implemented early in life. The biochemistry and physiology of MSUD and its response to liver transplantation afford key insights into the design of new therapies based on gene replacement or editing.
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Affiliation(s)
- Kevin A Strauss
- Clinic for Special Children, Strasburg, PA, USA; Department of Pediatrics, Penn Medicine-Lancaster General Hospital, Lancaster, PA, USA; Departments of Pediatrics and Molecular, Cell & Cancer Biology, University of Massachusetts School of Medicine, Worcester, MA, USA.
| | - Vincent J Carson
- Clinic for Special Children, Strasburg, PA, USA; Department of Pediatrics, Penn Medicine-Lancaster General Hospital, Lancaster, PA, USA
| | - Kyle Soltys
- Hillman Center for Pediatric Transplantation, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, USA
| | | | | | | | | | | | | | | | | | - Cora M Taylor
- Geisinger Autism & Developmental Medicine Institute, Lewisburg, PA, USA
| | | | - Stephanie Chopko
- Department of Pediatrics, Nemours Alfred I. duPont Hospital for Children, Wilmington, DE, USA; Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
| | | | - Emilie R Muelly
- Department of Internal Medicine, The Permanente Medical Group, Santa Clara, CA, USA
| | - Diana A Shellmer
- Hillman Center for Pediatric Transplantation, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, USA
| | - Zachary Radcliff
- Department of Pediatrics, Nemours Alfred I. duPont Hospital for Children, Wilmington, DE, USA
| | | | | | | | - George V Mazariegos
- Hillman Center for Pediatric Transplantation, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, USA
| | - D Holmes Morton
- Clinic for Special Children, Strasburg, PA, USA; Department of Pediatrics, Penn Medicine-Lancaster General Hospital, Lancaster, PA, USA; Central Pennsylvania Clinic, Belleville, PA, USA
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10
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Yang C, Linpeng S, Cao Y, Wu L. Identification of six novel mutations in five infants with suspected maple syrup urine disease based on blood and urine metabolism screening. Gene 2019; 710:9-16. [PMID: 31112740 DOI: 10.1016/j.gene.2019.04.086] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 04/09/2019] [Accepted: 04/30/2019] [Indexed: 11/18/2022]
Abstract
Maple syrup urine disease (MSUD) is a rare autosomal recessive genetic metabolic disease, with a high incidence rate in infants. We analyzed the data of molecular genetic analysis of five infants whose metabolism screening suspected MSUD and described their clinical symptoms. Further, we performed next-generation sequencing and Sanger sequencing to determine the genetic causes of the disease. Bioinformatics tools were used to predict the pathogenicity of novel mutations by performing structural modeling. All the five infants showed symptoms before one year of age and had elevated plasma leucine and valine levels. Among them, four infants presented an obvious increase in the urine lactic acid level. We identified the genetic cause of the disease in four infants and analyzed the pathogenicity of six novel mutations, viz., two mutations in BCKDHA (p.Gly180Asp and p.Arg265Gln), three in BCKDHB (p.Tyr169Cys, p.Ala331Thr, and p.Gly336Ser), and one in DBT (p.Leu69Arg), using in silico analysis. We also reviewed previously reported mutations in Chinese patients and summarized their genotypic and phenotypic characteristics. Our study has confirmed or corrected the clinical diagnosis and enriched the mutation spectrum of BCKDHA, BCKDHB, and DBT. We suggest blood and urine metabolism screening combined with next generation sequencing to diagnose MSUD, especially in infants, to achieve early diagnosis and early treatment.
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Affiliation(s)
- Chenxi Yang
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, China
| | - Siyuan Linpeng
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, China
| | - Yingxi Cao
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, China
| | - Lingqian Wu
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, China.
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11
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Liang Y, Kong F, Torres-Romero I, Burlacot A, Cuine S, Légeret B, Billon E, Brotman Y, Alseekh S, Fernie AR, Beisson F, Peltier G, Li-Beisson Y. Branched-Chain Amino Acid Catabolism Impacts Triacylglycerol Homeostasis in Chlamydomonas reinhardtii. Plant Physiol 2019; 179:1502-1514. [PMID: 30728273 PMCID: PMC6446750 DOI: 10.1104/pp.18.01584] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Accepted: 01/30/2019] [Indexed: 05/05/2023]
Abstract
Nitrogen (N) starvation-induced triacylglycerol (TAG) synthesis, and its complex relationship with starch metabolism in algal cells, has been intensively studied; however, few studies have examined the interaction between amino acid metabolism and TAG biosynthesis. Here, via a forward genetic screen for TAG homeostasis, we isolated a Chlamydomonas (Chlamydomonas reinhardtii) mutant (bkdE1α) that is deficient in the E1α subunit of the branched-chain ketoacid dehydrogenase (BCKDH) complex. Metabolomics analysis revealed a defect in the catabolism of branched-chain amino acids in bkdE1α Furthermore, this mutant accumulated 30% less TAG than the parental strain during N starvation and was compromised in TAG remobilization upon N resupply. Intriguingly, the rate of mitochondrial respiration was 20% to 35% lower in bkdE1α compared with the parental strains. Three additional knockout mutants of the other components of the BCKDH complex exhibited phenotypes similar to that of bkdE1α Transcriptional responses of BCKDH to different N status were consistent with its role in TAG homeostasis. Collectively, these results indicate that branched-chain amino acid catabolism contributes to TAG metabolism by providing carbon precursors and ATP, thus highlighting the complex interplay between distinct subcellular metabolisms for oil storage in green microalgae.
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Affiliation(s)
- Yuanxue Liang
- Aix-Marseille University, Commissariat à l'Energie Atomique, Centre National de la Recherche Scientifique, Bioscience and Biotechnology Institute of Aix-Marseille (BIAM), Commissariat à l'Energie Atomique Cadarache, Saint-Paul-lez Durance F-13108, France
| | - Fantao Kong
- Aix-Marseille University, Commissariat à l'Energie Atomique, Centre National de la Recherche Scientifique, Bioscience and Biotechnology Institute of Aix-Marseille (BIAM), Commissariat à l'Energie Atomique Cadarache, Saint-Paul-lez Durance F-13108, France
| | - Ismael Torres-Romero
- Aix-Marseille University, Commissariat à l'Energie Atomique, Centre National de la Recherche Scientifique, Bioscience and Biotechnology Institute of Aix-Marseille (BIAM), Commissariat à l'Energie Atomique Cadarache, Saint-Paul-lez Durance F-13108, France
| | - Adrien Burlacot
- Aix-Marseille University, Commissariat à l'Energie Atomique, Centre National de la Recherche Scientifique, Bioscience and Biotechnology Institute of Aix-Marseille (BIAM), Commissariat à l'Energie Atomique Cadarache, Saint-Paul-lez Durance F-13108, France
| | - Stéphan Cuine
- Aix-Marseille University, Commissariat à l'Energie Atomique, Centre National de la Recherche Scientifique, Bioscience and Biotechnology Institute of Aix-Marseille (BIAM), Commissariat à l'Energie Atomique Cadarache, Saint-Paul-lez Durance F-13108, France
| | - Bertrand Légeret
- Aix-Marseille University, Commissariat à l'Energie Atomique, Centre National de la Recherche Scientifique, Bioscience and Biotechnology Institute of Aix-Marseille (BIAM), Commissariat à l'Energie Atomique Cadarache, Saint-Paul-lez Durance F-13108, France
| | - Emmanuelle Billon
- Aix-Marseille University, Commissariat à l'Energie Atomique, Centre National de la Recherche Scientifique, Bioscience and Biotechnology Institute of Aix-Marseille (BIAM), Commissariat à l'Energie Atomique Cadarache, Saint-Paul-lez Durance F-13108, France
| | - Yariv Brotman
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Saleh Alseekh
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Alisdair R Fernie
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Fred Beisson
- Aix-Marseille University, Commissariat à l'Energie Atomique, Centre National de la Recherche Scientifique, Bioscience and Biotechnology Institute of Aix-Marseille (BIAM), Commissariat à l'Energie Atomique Cadarache, Saint-Paul-lez Durance F-13108, France
| | - Gilles Peltier
- Aix-Marseille University, Commissariat à l'Energie Atomique, Centre National de la Recherche Scientifique, Bioscience and Biotechnology Institute of Aix-Marseille (BIAM), Commissariat à l'Energie Atomique Cadarache, Saint-Paul-lez Durance F-13108, France
| | - Yonghua Li-Beisson
- Aix-Marseille University, Commissariat à l'Energie Atomique, Centre National de la Recherche Scientifique, Bioscience and Biotechnology Institute of Aix-Marseille (BIAM), Commissariat à l'Energie Atomique Cadarache, Saint-Paul-lez Durance F-13108, France
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12
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Li X, Yang Y, Gao Q, Gao M, Lv Y, Dong R, Liu Y, Zhang K, Gai Z. Clinical characteristics and mutation analysis of five Chinese patients with maple syrup urine disease. Metab Brain Dis 2018; 33:741-751. [PMID: 29307017 DOI: 10.1007/s11011-017-0168-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 12/11/2017] [Indexed: 11/28/2022]
Abstract
Maple syrup urine disease (MSUD) is an autosomal recessive disorder affecting branched-chain amino acids (BCAAs) metabolism and caused by a defect in the thiamine-dependent enzyme branched chain α-ketoacid dehydrogenase (BCKD) with subsequent accumulation of BCAAs and corresponding branched-chain keto acids (BCKAs) metabolites. Presently, at least 4 genes of BCKDHA, BCKDHB, DLD and DBT have been reported to cause MSUD. Furthermore, more than 265 mutations have been identified as the cause across different populations worldwide. Some studies have reported the data of gene mutations in Chinese people with MSUD. In this study, we present clinical characteristics and mutational analyses in five Chinese Han child with MSUD, which had been screened out by tandem mass spectrometry detection of amino acids in blood samples. High-throughput sequencing, Sanger sequence and real-time qualitative PCR were performed to detect and verify the genetic mutations. Six different novel genetic variants were validated in BCKDHB gene and BCKDHA gene, including c.523 T > C, c.659delA, c.550delT, c.863G > A and two gross deletions. Interestingly, 3 cases had identical mutation of BCKDHB gene (c.659delA). We predicted the pathogenicity and analyzed the clinical characteristics. The identification of these mutations in this study further expands the mutation spectrum of MSUD and contributes to prenatal molecular diagnosis of MSUD.
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Affiliation(s)
- Xiaomei Li
- Department of Neonatology, Qilu Children's Hospital of Shandong University, Jinan, Shandong, 250022, China
| | - Yali Yang
- Department of Rehabilitation, Qilu Children's Hospital of Shandong University, Jinan, Shandong, 250022, China
| | - Qing Gao
- Department of Genetics, Jinan Maternity and Child Care Hospital, Jinan, Shandong, 250001, China
| | - Min Gao
- Pediatric Research Institute, Qilu Children's Hospital of Shandong University, 23976 Jingshi Road, Jinan, Shandong, 250022, China
| | - Yvqiang Lv
- Pediatric Research Institute, Qilu Children's Hospital of Shandong University, 23976 Jingshi Road, Jinan, Shandong, 250022, China
| | - Rui Dong
- Pediatric Research Institute, Qilu Children's Hospital of Shandong University, 23976 Jingshi Road, Jinan, Shandong, 250022, China
| | - Yi Liu
- Pediatric Research Institute, Qilu Children's Hospital of Shandong University, 23976 Jingshi Road, Jinan, Shandong, 250022, China
| | - Kaihui Zhang
- Pediatric Research Institute, Qilu Children's Hospital of Shandong University, 23976 Jingshi Road, Jinan, Shandong, 250022, China.
| | - Zhongtao Gai
- Pediatric Research Institute, Qilu Children's Hospital of Shandong University, 23976 Jingshi Road, Jinan, Shandong, 250022, China.
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13
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Su L, Lu Z, Li F, Shao Y, Sheng H, Cai Y, Liu L. Two homozygous mutations in the exon 5 of BCKDHB gene that may cause the classic form of maple syrup urine disease. Metab Brain Dis 2017; 32:765-772. [PMID: 28197878 DOI: 10.1007/s11011-017-9959-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2016] [Accepted: 01/24/2017] [Indexed: 01/16/2023]
Abstract
Maple syrup urine disease (MSUD) is a rare autosomal recessive genetic disorder caused by defects in the catabolism of the branched-chain amino acids (BCAAs). Classic form of MSUD (CMSUD) is caused by mutations in BCKDHA, BCKDHB, DBT genes mostly. In this study, we analyzed the clinical and genetic characteristics of two patients with CMSUD. Two homozygous mutations, c.517G > T (p.Asp173Tyr) and c.503G > A (p.Arg168His), both in the exon 5 of BCKDHB were detected respectively. The novel mutation p.Asp173Tyr of patient A, inherited from his parents, is predicted to affect conformation of protein by computer analysis. The reported mutation p.Arg168His observed in patient B seemed to occur in a maternal uniparental disomy inheritance manner. Review of related literature revealed that most missense mutations in exon 5 of BCKDHB in homozygous genotype often result in CMSUD because of its incorrect conformation, and exon 5 of BCKDHB might be a susceptible region. Thus the novel homozygous mutation p.Asp173Tyr and the founder homozygous mutation p.Arg168His may be responsible for the clinical presentation of the two CMSUD patients, facilitating the future genetic counselling and prenatal diagnosis.
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Affiliation(s)
- Ling Su
- Department of Genetics and Endocrinology, Guangzhou women and children's medical center, Guangzhou Medical University, 9 Jinsui Road, Guangzhou, Guangdong province, 510623, China
| | - Zhikun Lu
- Department of Genetics and Endocrinology, Guangzhou women and children's medical center, Guangzhou Medical University, 9 Jinsui Road, Guangzhou, Guangdong province, 510623, China
| | - Fatao Li
- Prenatal Diagnostic Center, Guangzhou women and children's medical center, Guangzhou Medical University, Guangzhou, 510623, China
| | - Yongxian Shao
- Department of Genetics and Endocrinology, Guangzhou women and children's medical center, Guangzhou Medical University, 9 Jinsui Road, Guangzhou, Guangdong province, 510623, China
| | - Huiying Sheng
- Department of Genetics and Endocrinology, Guangzhou women and children's medical center, Guangzhou Medical University, 9 Jinsui Road, Guangzhou, Guangdong province, 510623, China
| | - Yanna Cai
- Department of Genetics and Endocrinology, Guangzhou women and children's medical center, Guangzhou Medical University, 9 Jinsui Road, Guangzhou, Guangdong province, 510623, China
| | - Li Liu
- Department of Genetics and Endocrinology, Guangzhou women and children's medical center, Guangzhou Medical University, 9 Jinsui Road, Guangzhou, Guangdong province, 510623, China.
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14
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Luu VT, Weinhold A, Ullah C, Dressel S, Schoettner M, Gase K, Gaquerel E, Xu S, Baldwin IT. O-Acyl Sugars Protect a Wild Tobacco from Both Native Fungal Pathogens and a Specialist Herbivore. Plant Physiol 2017; 174:370-386. [PMID: 28275149 PMCID: PMC5411141 DOI: 10.1104/pp.16.01904] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 03/06/2017] [Indexed: 05/04/2023]
Abstract
O-Acyl sugars (O-AS) are abundant trichome-specific metabolites that function as indirect defenses against herbivores of the wild tobacco Nicotiana attenuata; whether they also function as generalized direct defenses against herbivores and pathogens remains unknown. We characterized natural variation in O-AS among 26 accessions and examined their influence on two native fungal pathogens, Fusarium brachygibbosum U4 and Alternaria sp. U10, and the specialist herbivore Manduca sexta At least 15 different O-AS structures belonging to three classes were found in N. attenuata leaves. A 3-fold quantitative variation in total leaf O-AS was found among the natural accessions. Experiments with natural accessions and crosses between high- and low-O-AS accessions revealed that total O-AS levels were associated with resistance against herbivores and pathogens. Removing O-AS from the leaf surface increased M. sexta growth rate and plant fungal susceptibility. O-AS supplementation in artificial diets and germination medium reduced M. sexta growth and fungal spore germination, respectively. Finally, silencing the expression of a putative branched-chain α-ketoacid dehydrogenase E1 β-subunit-encoding gene (NaBCKDE1B) in the trichomes reduced total leaf O-AS by 20% to 30% and increased susceptibility to Fusarium pathogens. We conclude that O-AS function as direct defenses to protect plants from attack by both native pathogenic fungi and a specialist herbivore and infer that their diversification is likely shaped by the functional interactions among these biotic stresses.
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Affiliation(s)
- Van Thi Luu
- Department of Molecular Ecology (V.T.L., S.D., M.S., K.G., S.X., I.T.B.) and Department of Biochemistry (C.U.), Max Planck Institute for Chemical Ecology, Jena 07745, Germany
- Department of Molecular Interaction Ecology, German Centre for Integrative Biodiversity Research, Leipzig 04103, Germany (A.W); and
- Centre for Organismal Studies, University of Heidelberg, Heidelberg 69120, Germany (E.G.)
| | - Alexander Weinhold
- Department of Molecular Ecology (V.T.L., S.D., M.S., K.G., S.X., I.T.B.) and Department of Biochemistry (C.U.), Max Planck Institute for Chemical Ecology, Jena 07745, Germany
- Department of Molecular Interaction Ecology, German Centre for Integrative Biodiversity Research, Leipzig 04103, Germany (A.W); and
- Centre for Organismal Studies, University of Heidelberg, Heidelberg 69120, Germany (E.G.)
| | - Chhana Ullah
- Department of Molecular Ecology (V.T.L., S.D., M.S., K.G., S.X., I.T.B.) and Department of Biochemistry (C.U.), Max Planck Institute for Chemical Ecology, Jena 07745, Germany
- Department of Molecular Interaction Ecology, German Centre for Integrative Biodiversity Research, Leipzig 04103, Germany (A.W); and
- Centre for Organismal Studies, University of Heidelberg, Heidelberg 69120, Germany (E.G.)
| | - Stefanie Dressel
- Department of Molecular Ecology (V.T.L., S.D., M.S., K.G., S.X., I.T.B.) and Department of Biochemistry (C.U.), Max Planck Institute for Chemical Ecology, Jena 07745, Germany
- Department of Molecular Interaction Ecology, German Centre for Integrative Biodiversity Research, Leipzig 04103, Germany (A.W); and
- Centre for Organismal Studies, University of Heidelberg, Heidelberg 69120, Germany (E.G.)
| | - Matthias Schoettner
- Department of Molecular Ecology (V.T.L., S.D., M.S., K.G., S.X., I.T.B.) and Department of Biochemistry (C.U.), Max Planck Institute for Chemical Ecology, Jena 07745, Germany
- Department of Molecular Interaction Ecology, German Centre for Integrative Biodiversity Research, Leipzig 04103, Germany (A.W); and
- Centre for Organismal Studies, University of Heidelberg, Heidelberg 69120, Germany (E.G.)
| | - Klaus Gase
- Department of Molecular Ecology (V.T.L., S.D., M.S., K.G., S.X., I.T.B.) and Department of Biochemistry (C.U.), Max Planck Institute for Chemical Ecology, Jena 07745, Germany
- Department of Molecular Interaction Ecology, German Centre for Integrative Biodiversity Research, Leipzig 04103, Germany (A.W); and
- Centre for Organismal Studies, University of Heidelberg, Heidelberg 69120, Germany (E.G.)
| | - Emmanuel Gaquerel
- Department of Molecular Ecology (V.T.L., S.D., M.S., K.G., S.X., I.T.B.) and Department of Biochemistry (C.U.), Max Planck Institute for Chemical Ecology, Jena 07745, Germany
- Department of Molecular Interaction Ecology, German Centre for Integrative Biodiversity Research, Leipzig 04103, Germany (A.W); and
- Centre for Organismal Studies, University of Heidelberg, Heidelberg 69120, Germany (E.G.)
| | - Shuqing Xu
- Department of Molecular Ecology (V.T.L., S.D., M.S., K.G., S.X., I.T.B.) and Department of Biochemistry (C.U.), Max Planck Institute for Chemical Ecology, Jena 07745, Germany
- Department of Molecular Interaction Ecology, German Centre for Integrative Biodiversity Research, Leipzig 04103, Germany (A.W); and
- Centre for Organismal Studies, University of Heidelberg, Heidelberg 69120, Germany (E.G.)
| | - Ian T Baldwin
- Department of Molecular Ecology (V.T.L., S.D., M.S., K.G., S.X., I.T.B.) and Department of Biochemistry (C.U.), Max Planck Institute for Chemical Ecology, Jena 07745, Germany;
- Department of Molecular Interaction Ecology, German Centre for Integrative Biodiversity Research, Leipzig 04103, Germany (A.W); and
- Centre for Organismal Studies, University of Heidelberg, Heidelberg 69120, Germany (E.G.)
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15
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Li T, Wang Y, Li C, Xu WW, Niu FH, Zhang D. [Maple syrup urine disease and gene mutations in twin neonates]. Zhongguo Dang Dai Er Ke Za Zhi 2016; 18:1242-1246. [PMID: 27974115 PMCID: PMC7403074 DOI: 10.7499/j.issn.1008-8830.2016.12.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 09/12/2016] [Indexed: 06/06/2023]
Abstract
OBJECTIVE To investigate the clinical features of one pair of twin neonates with maple syrup urine disease (MSUD) in the Chinese Han population and pathogenic mutations in related genes, and to provide guidance for the early diagnosis and treatment of MSUD. METHODS The clinical and imaging data of the twin neonates were collected. The peripheral blood samples were collected from the twin neonates and their parents to detect the genes related to MSUD (BCKDHA, BCKDHB, DBT, and DLD). The loci with gene mutations were identified, and a bioinformatic analysis was performed. RESULTS Two mutations were detected in the BCKDHB gene, missense mutation c.304G>A (p.Gly102Arg) and nonsense mutation c.331C>T (p.Arg111*), and both of them were heterozygotes. The mutation c.304G>A (p.Gly102Arg) had not been reported in the world. Their father carried the missense mutation c.304G>A (p.Gly102Arg), and their mother carried the nonsense mutation c.331C>T (p.Arg111*). CONCLUSIONS The c.331C>T (p.Arg111*) heterozygous mutation in BCKDHB gene is the pathogenic mutation in these twin neonates and provides a genetic and molecular basis for the clinical features of children with MSUD.
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Affiliation(s)
- Tao Li
- Department of Pediatrics, Affiliated Hospital of Jining Medical University, Jining, Shandong 272000, China.
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16
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Tort F, Ferrer-Cortes X, Ribes A. Differential diagnosis of lipoic acid synthesis defects. J Inherit Metab Dis 2016; 39:781-793. [PMID: 27586888 DOI: 10.1007/s10545-016-9975-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 08/02/2016] [Accepted: 08/04/2016] [Indexed: 01/16/2023]
Abstract
Lipoic acid (LA) is an essential cofactor required for the activity of five multienzymatic complexes that play a central role in the mitochondrial energy metabolism: four 2-oxoacid dehydrogenase complexes [pyruvate dehydrogenase (PDH), branched-chain ketoacid dehydrogenase (BCKDH), 2-ketoglutarate dehydrogenase (2-KGDH), and 2-oxoadipate dehydrogenase (2-OADH)] and the glycine cleavage system (GCS). LA is synthesized in a complex multistep process that requires appropriate function of the mitochondrial fatty acid synthesis (mtFASII) and the biogenesis of iron-sulphur (Fe-S) clusters. Defects in the biosynthesis of LA have been reported to be associated with multiple and severe defects of the mitochondrial energy metabolism. In recent years, disease-causing mutations in genes encoding for proteins involved in LA metabolism have been reported: NFU1, BOLA3, IBA57, LIAS, GLRX5, LIPT1, ISCA2, and LIPT2. These studies represented important progress in understanding the pathophysiology and molecular bases underlying these disorders. Here we review current knowledge regarding involvement of LA synthesis defects in human diseases with special emphasis on the diagnostic strategies for these disorders. The clinical and biochemical characteristics of patients with LA synthesis defects are discussed and a workup for the differential diagnosis proposed.
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Affiliation(s)
- Frederic Tort
- Secció d'Errors Congènits del Metabolisme -IBC, Servei de Bioquímica i Genètica Molecular, Hospital Clínic, IDIBAPS, CIBERER, Edifici Helios III, planta baixa, C/Mejía Lequerica s/n, 08028, Barcelona, Spain.
| | - Xènia Ferrer-Cortes
- Secció d'Errors Congènits del Metabolisme -IBC, Servei de Bioquímica i Genètica Molecular, Hospital Clínic, IDIBAPS, CIBERER, Edifici Helios III, planta baixa, C/Mejía Lequerica s/n, 08028, Barcelona, Spain
| | - Antonia Ribes
- Secció d'Errors Congènits del Metabolisme -IBC, Servei de Bioquímica i Genètica Molecular, Hospital Clínic, IDIBAPS, CIBERER, Edifici Helios III, planta baixa, C/Mejía Lequerica s/n, 08028, Barcelona, Spain
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17
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Sirobhushanam S, Galva C, Sen S, Wilkinson BJ, Gatto C. Broad substrate specificity of phosphotransbutyrylase from Listeria monocytogenes: A potential participant in an alternative pathway for provision of acyl CoA precursors for fatty acid biosynthesis. Biochim Biophys Acta 2016; 1861:1102-1110. [PMID: 27320015 PMCID: PMC4947441 DOI: 10.1016/j.bbalip.2016.06.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 05/20/2016] [Accepted: 06/10/2016] [Indexed: 12/22/2022]
Abstract
Listeria monocytogenes, the causative organism of the serious food-borne disease listeriosis, has a membrane abundant in branched-chain fatty acids (BCFAs). BCFAs are normally biosynthesized from branched-chain amino acids via the activity of branched chain α-keto acid dehydrogenase (Bkd), and disruption of this pathway results in reduced BCFA content in the membrane. Short branched-chain carboxylic acids (BCCAs) added as media supplements result in incorporation of BCFAs arising from the supplemented BCCAs in the membrane of L. monocytogenes bkd mutant MOR401. High concentrations of the supplements also effect similar changes in the membrane of the wild type organism with intact bkd. Such carboxylic acids clearly act as fatty acid precursors, and there must be an alternative pathway resulting in the formation of their CoA thioester derivatives. Candidates for this are the enzymes phosphotransbutyrylase (Ptb) and butyrate kinase (Buk), the products of the first two genes of the bkd operon. Ptb from L. monocytogenes exhibited broad substrate specificity, a strong preference for branched-chain substrates, a lack of activity with acetyl CoA and hexanoyl CoA, and strict chain length preference (C3-C5). Ptb catalysis involved ternary complex formation. Additionally, Ptb could utilize unnatural branched-chain substrates such as 2-ethylbutyryl CoA, albeit with lower efficiency, consistent with a potential involvement of this enzyme in the conversion of the carboxylic acid additives into CoA primers for BCFA biosynthesis.
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Affiliation(s)
| | - Charitha Galva
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Suranjana Sen
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Brian J Wilkinson
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Craig Gatto
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA.
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Zigler JS, Hodgkinson CA, Wright M, Klise A, Sundin O, Broman KW, Hejtmancik F, Huang H, Patek B, Sergeev Y, Hose S, Brayton C, Xaiodong J, Vasquez D, Maragakis N, Mori S, Goldman D, Hoke A, Sinha D. A Spontaneous Missense Mutation in Branched Chain Keto Acid Dehydrogenase Kinase in the Rat Affects Both the Central and Peripheral Nervous Systems. PLoS One 2016; 11:e0160447. [PMID: 27472223 PMCID: PMC4966912 DOI: 10.1371/journal.pone.0160447] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 07/19/2016] [Indexed: 11/19/2022] Open
Abstract
A novel mutation, causing a phenotype we named frogleg because its most obvious characteristic is a severe splaying of the hind limbs, arose spontaneously in a colony of Sprague-Dawley rats. Frogleg is a complex phenotype that includes abnormalities in hind limb function, reduced brain weight with dilated ventricles and infertility. Using micro-satellite markers spanning the entire rat genome, the mutation was mapped to a region of rat chromosome 1 between D1Rat131 and D1Rat287. Analysis of whole genome sequencing data within the linkage interval, identified a missense mutation in the branched-chain alpha-keto dehydrogenase kinase (Bckdk) gene. The protein encoded by Bckdk is an integral part of an enzyme complex located in the mitochondrial matrix of many tissues which regulates the levels of the branched-chain amino acids (BCAAs), leucine, isoleucine and valine. BCAAs are essential amino acids (not synthesized by the body), and circulating levels must be tightly regulated; levels that are too high or too low are both deleterious. BCKDK phosphorylates Ser293 of the E1α subunit of the BCKDH protein, which catalyzes the rate-limiting step in the catabolism of the BCAAs, inhibiting BCKDH and thereby, limiting breakdown of the BCAAs. In contrast, when Ser293 is not phosphorylated, BCKDH activity is unchecked and the levels of the BCAAs will decrease dramatically. The mutation is located within the kinase domain of Bckdk and is predicted to be damaging. Consistent with this, we show that in rats homozygous for the mutation, phosphorylation of BCKDH in the brain is markedly decreased relative to wild type or heterozygous littermates. Further, circulating levels of the BCAAs are reduced by 70-80% in animals homozygous for the mutation. The frogleg phenotype shares important characteristics with a previously described Bckdk knockout mouse and with human subjects with Bckdk mutations. In addition, we report novel data regarding peripheral neuropathy of the hind limbs.
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Affiliation(s)
- J. Samuel Zigler
- Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Colin A. Hodgkinson
- National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, MD, United States of America
| | - Megan Wright
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Andrew Klise
- Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Olof Sundin
- Department of Biomedical Sciences, Texas Tech University Health Science Center, El Paso, TX, United States of America
| | - Karl W. Broman
- Department of Biostatistics & Informatics, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States of America
| | - Fielding Hejtmancik
- National Eye Institute, National Institutes of Health, Bethesda, MD, United States of America
| | - Hao Huang
- Department of Radiology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Bonnie Patek
- Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Yuri Sergeev
- National Eye Institute, National Institutes of Health, Bethesda, MD, United States of America
| | - Stacey Hose
- Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Cory Brayton
- Department of Molecular and Comparative Pathobiology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Jiao Xaiodong
- National Eye Institute, National Institutes of Health, Bethesda, MD, United States of America
| | - David Vasquez
- Department of Neurosurgery, The Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Nicholas Maragakis
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Susumu Mori
- Department of Radiology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - David Goldman
- National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, MD, United States of America
| | - Ahmet Hoke
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Debasish Sinha
- Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
- * E-mail:
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Feier F, Schwartz IVD, Benkert AR, Seda Neto J, Miura I, Chapchap P, da Fonseca EA, Vieira S, Zanotelli ML, Pinto e Vairo F, Camelo JS, Margutti AVB, Mazariegos GV, Puffenberger EG, Strauss KA. Living related versus deceased donor liver transplantation for maple syrup urine disease. Mol Genet Metab 2016; 117:336-43. [PMID: 26786177 DOI: 10.1016/j.ymgme.2016.01.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2015] [Revised: 01/10/2016] [Accepted: 01/10/2016] [Indexed: 01/04/2023]
Abstract
Maple syrup urine disease (MSUD) is an inherited disorder of branched chain ketoacid (BCKA) oxidation associated with episodic and chronic brain disease. Transplantation of liver from an unrelated deceased donor restores 9-13% whole-body BCKA oxidation capacity and stabilizes MSUD. Recent reports document encouraging short-term outcomes for MSUD patients who received a liver segment from mutation heterozygous living related donors (LRDT). To investigate effects of living related versus deceased unrelated grafts, we studied four Brazilian MSUD patients treated with LRDT who were followed for a mean 19 ± 12 postoperative months, and compared metabolic and clinical outcomes to 37 classical MSUD patients treated with deceased donor transplant. Patient and graft survival for LRDT were 100%. Three of 4 MSUD livers were successfully domino transplanted into non-MSUD subjects. Following LRDT, all subjects resumed a protein-unrestricted diet as mean plasma leucine decreased from 224 ± 306 μM to 143 ± 44 μM and allo-isoleucine decreased 91%. We observed no episodes of hyperleucinemia during 80 aggregate postoperative patient-months. Mean plasma leucine:isoleucine:valine concentration ratios were ~2:1:4 after deceased donor transplant compared to ~1:1:1.5 following LRDT, resulting in differences of predicted cerebral amino acid uptake. Mutant heterozygous liver segments effectively maintain steady-state BCAA and BCKA homeostasis on an unrestricted diet and during most catabolic states, but might have different metabolic effects than grafts from unrelated deceased donors. Neither living related nor deceased donor transplant affords complete protection from metabolic intoxication, but both strategies represent viable alternatives to nutritional management.
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Affiliation(s)
- Flavia Feier
- Hospital Sirio Libanes, São Paulo, Brazil; Hospital Santa Casa de Misericórdia, Porto Alegre, Brazil
| | - Ida Vanessa D Schwartz
- Medical Genetics Service, Hospital de Clinicas de Porto Alegre, Brazil; Genetics Department, Universidade Federal do Rio Grande do Sul, Brazil
| | | | | | | | | | | | - Sandra Vieira
- Pediatrics Department, Universidade Federal do Rio Grande do Sul, Brazil; Pediatrics Liver Transplantation Program, Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil
| | - Maria Lúcia Zanotelli
- Pediatrics Liver Transplantation Program, Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil
| | | | - Jose Simon Camelo
- Pediatrics Department, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | | | - George V Mazariegos
- Hillman Center for Pediatric Transplantation, Children's Hospital of UPMC, Pittsburgh, PA, USA
| | - Erik G Puffenberger
- Clinic for Special Children, Strasburg, PA, USA; Franklin & Marshall College, Lancaster, PA, USA
| | - Kevin A Strauss
- Clinic for Special Children, Strasburg, PA, USA; Franklin & Marshall College, Lancaster, PA, USA; Lancaster General Hospital, Lancaster, PA, USA.
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20
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Zhao X, Han Q, Liu Y, Sun C, Gang X, Wang G. The Relationship between Branched-Chain Amino Acid Related Metabolomic Signature and Insulin Resistance: A Systematic Review. J Diabetes Res 2016; 2016:2794591. [PMID: 27642608 PMCID: PMC5014958 DOI: 10.1155/2016/2794591] [Citation(s) in RCA: 96] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2016] [Revised: 07/16/2016] [Accepted: 08/01/2016] [Indexed: 01/22/2023] Open
Abstract
Recent studies have shown the positive association between increased circulating BCAAs (valine, leucine, and isoleucine) and insulin resistance (IR) in obese or diabetic patients. However, results seem to be controversial in different races, diets, and distinct tissues. Our aims were to evaluate the relationship between BCAA and IR as well as later diabetes risk and explore the phenotypic and genetic factors influencing BCAA level based on available studies. We performed systematic review, searching MEDLINE, EMASE, ClinicalTrials.gov, the Cochrane Library, and Web of Science from inception to March 2016. After selection, 23 studies including 20,091 participants were included. Based on current evidence, we found that BCAA is a useful biomarker for early detection of IR and later diabetic risk. Factors influencing BCAA level can be divided into four parts: race, gender, dietary patterns, and gene variants. These factors might not only contribute to the elevated BCAA level but also show obvious associations with insulin resistance. Genes related to BCAA catabolism might serve as potential targets for the treatment of IR associated metabolic disorders. Moreover, these factors should be controlled properly during study design and data analysis. In the future, more large-scale studies with elaborate design addressing BCAA and IR are required.
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Affiliation(s)
- Xue Zhao
- Department of Endocrinology and Metabolism, The First Hospital of Jilin University, Changchun 130021, China
| | - Qing Han
- Hospital of Orthopedics, The Second Hospital of Jilin University, Changchun 130021, China
| | - Yujia Liu
- Department of Endocrinology and Metabolism, The First Hospital of Jilin University, Changchun 130021, China
| | - Chenglin Sun
- Department of Endocrinology and Metabolism, The First Hospital of Jilin University, Changchun 130021, China
| | - Xiaokun Gang
- Department of Endocrinology and Metabolism, The First Hospital of Jilin University, Changchun 130021, China
- *Xiaokun Gang: and
| | - Guixia Wang
- Department of Endocrinology and Metabolism, The First Hospital of Jilin University, Changchun 130021, China
- *Guixia Wang:
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21
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Guo Y, Liming L, Jiang L. Two novel compound heterozygous mutations in the BCKDHB gene that cause the intermittent form of maple syrup urine disease. Metab Brain Dis 2015; 30:1395-400. [PMID: 26239723 DOI: 10.1007/s11011-015-9711-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2015] [Accepted: 07/15/2015] [Indexed: 10/23/2022]
Abstract
Intermittent maple syrup urine disease (MSUD) is a potentially life-threatening metabolic disorder caused by a deficiency of branched chain α-ketoacid dehydrogenase (BCKD) complex. In contrast to classic MSUD, children with the intermittent form usually have an atypical clinical manifestation. Here, we describe the presenting symptoms and clinical course of a Chinese boy with intermittent MSUD. Mutation analysis identified two previously unreported mutations in exon 7 of the BCKDHB gene: c.767A > G (p.Y256C) and c.768C > G (p.Y256X); the parents were each heterozygous for one of these mutations. In silico analysis predicted Y256C probably affects protein structure; Y256X leads to a premature stop codon. This case demonstrates intermittent MSUD should be suspected in cases with symptoms of recurrent encephalopathy, especially ataxia or marked drowsiness, which usually present after the neonatal period and in conjunction with infection. symmetrical basal ganglia damage but normal myelination in the posterior limb will assist differential diagnosis; alloisoleucine is a useful diagnostic marker and mutation analysis may be of prognostic value. These novel mutations Y256C and Y256X result in the clinical manifestation of a variant form of MSUD, expanding the mutation spectrum of this disease.
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Affiliation(s)
- Yi Guo
- Department of Neurology, Children's Hospital of Chongqing Medical University, Chongqing, China, 400014.
| | - Liu Liming
- Ministry of Education Key Laboratory of Child Development and Disorders, Key Laboratory of Pediatrics in Chongqing, Chongqing International Science and Technology Cooperation Center for Child Development and Disorders, Chongqing, China.
| | - Li Jiang
- Department of Neurology, Children's Hospital of Chongqing Medical University, Chongqing, China, 400014.
- Ministry of Education Key Laboratory of Child Development and Disorders, Key Laboratory of Pediatrics in Chongqing, Chongqing International Science and Technology Cooperation Center for Child Development and Disorders, Chongqing, China.
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22
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Peng C, Uygun S, Shiu SH, Last RL. The Impact of the Branched-Chain Ketoacid Dehydrogenase Complex on Amino Acid Homeostasis in Arabidopsis. Plant Physiol 2015; 169:1807-20. [PMID: 25986129 PMCID: PMC4634046 DOI: 10.1104/pp.15.00461] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 05/15/2015] [Indexed: 05/05/2023]
Abstract
The branched-chain amino acids (BCAAs) Leu, Ile, and Val are among nine essential amino acids that must be obtained from the diet of humans and other animals, and can be nutritionally limiting in plant foods. Despite genetic evidence of its importance in regulating seed amino acid levels, the full BCAA catabolic network is not completely understood in plants, and limited information is available regarding its regulation. In this study, transcript coexpression analyses revealed positive correlations among BCAA catabolism genes in stress, development, diurnal/circadian, and light data sets. A core subset of BCAA catabolism genes, including those encoding putative branched-chain ketoacid dehydrogenase subunits, is highly expressed during the night in plants on a diel cycle and in prolonged darkness. Mutants defective in these subunits accumulate higher levels of BCAAs in mature seeds, providing genetic evidence for their function in BCAA catabolism. In addition, prolonged dark treatment caused the mutants to undergo senescence early and overaccumulate leaf BCAAs. These results extend the previous evidence that BCAAs can be catabolized and serve as respiratory substrates at multiple steps. Moreover, comparison of amino acid profiles between mature seeds and dark-treated leaves revealed differences in amino acid accumulation when BCAA catabolism is perturbed. Together, these results demonstrate the consequences of blocking BCAA catabolism during both normal growth conditions and under energy-limited conditions.
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Affiliation(s)
- Cheng Peng
- Department of Plant Biology (C.P., S.-H.S., R.L.L.), Department of Energy Plant Research Laboratory (C.P., S.U.), Genetics Program (S.U., S.-H.S.), and Department of Biochemistry and Molecular Biology (R.L.L.), Michigan State University, East Lansing, Michigan 48824
| | - Sahra Uygun
- Department of Plant Biology (C.P., S.-H.S., R.L.L.), Department of Energy Plant Research Laboratory (C.P., S.U.), Genetics Program (S.U., S.-H.S.), and Department of Biochemistry and Molecular Biology (R.L.L.), Michigan State University, East Lansing, Michigan 48824
| | - Shin-Han Shiu
- Department of Plant Biology (C.P., S.-H.S., R.L.L.), Department of Energy Plant Research Laboratory (C.P., S.U.), Genetics Program (S.U., S.-H.S.), and Department of Biochemistry and Molecular Biology (R.L.L.), Michigan State University, East Lansing, Michigan 48824
| | - Robert L Last
- Department of Plant Biology (C.P., S.-H.S., R.L.L.), Department of Energy Plant Research Laboratory (C.P., S.U.), Genetics Program (S.U., S.-H.S.), and Department of Biochemistry and Molecular Biology (R.L.L.), Michigan State University, East Lansing, Michigan 48824
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23
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Boulet MM, Chevrier G, Grenier-Larouche T, Pelletier M, Nadeau M, Scarpa J, Prehn C, Marette A, Adamski J, Tchernof A. Alterations of plasma metabolite profiles related to adipose tissue distribution and cardiometabolic risk. Am J Physiol Endocrinol Metab 2015; 309:E736-46. [PMID: 26306599 DOI: 10.1152/ajpendo.00231.2015] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 08/11/2015] [Indexed: 12/17/2022]
Abstract
Metabolomic profiling of obese individuals revealed altered concentrations of many metabolites, especially branched-chain amino acids (BCAA), possibly linked to altered adipose tissue BCAA catabolism. We tested the hypothesis that some features of this metabolite signature relate closely to visceral obesity and concomitant alterations in cardiometabolic risk factors. We also postulated that alterations in BCAA-catabolizing enzymes are predominant in visceral adipose tissue. Fifty-nine women (BMI 20-41 kg/m(2)) undergoing gynecologic surgery were recruited and characterized for overall and regional adiposity, blood metabolite levels using targeted metabolomics, and cardiometabolic risk factors. Adipose samples (visceral and subcutaneous) were obtained and used for gene expression and Western blot analyses. Obese women had significantly higher circulating BCAA and kynurenine/tryptophan (Kyn/Trp) ratio than lean or overweight women (P < 0.01). Principal component analysis confirmed that factors related to AA and the Kyn/Trp ratio were positively associated with BMI, fat mass, visceral or subcutaneous adipose tissue area, and subcutaneous adipocyte size (P ≤ 0.05). AA-related factor was positively associated with HOMA-IR (P ≤ 0.01). Factors reflecting glycerophospholipids and sphingolipids levels were mostly associated with altered blood lipid concentrations (P ≤ 0.05). Glutamate level was the strongest independent predictor of visceral adipose tissue area (r = 0.46, P < 0.001). Obese women had lower expression and protein levels of BCAA-catabolizing enzymes in visceral adipose tissue than overweight or lean women (P ≤ 0.05). We conclude that among metabolites altered in obesity plasma concentrations of BCAA and the Kyn/Trp ratio are closely related to increased adiposity. Alterations in expression and protein levels of BCAA-catabolizing enzymes are predominant in visceral adipose tissue.
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Affiliation(s)
- Marie Michèle Boulet
- Endocrinology and Nephrology, Centre Hospitalier Universitaire de Quebec, Quebec City, Canada; School of Nutrition, Laval University, Quebec City, Canada; Quebec Heart and Lung Institute, Quebec City, Canada
| | | | | | - Mélissa Pelletier
- Endocrinology and Nephrology, Centre Hospitalier Universitaire de Quebec, Quebec City, Canada
| | | | - Julia Scarpa
- Helmholtz Zentrum München, Institute of Experimental Genetics, Genome Analysis Center, Neuherberg, Germany
| | - Cornelia Prehn
- Helmholtz Zentrum München, Institute of Experimental Genetics, Genome Analysis Center, Neuherberg, Germany
| | - André Marette
- Quebec Heart and Lung Institute, Quebec City, Canada
| | - Jerzy Adamski
- Helmholtz Zentrum München, Institute of Experimental Genetics, Genome Analysis Center, Neuherberg, Germany; Lehrstuhl für Experimentelle Genetik, Technische Universität München, Freising-Weihenstephan, Germany; and German Center for Diabetes Research, Neuherberg, Germany
| | - André Tchernof
- Endocrinology and Nephrology, Centre Hospitalier Universitaire de Quebec, Quebec City, Canada; School of Nutrition, Laval University, Quebec City, Canada; Quebec Heart and Lung Institute, Quebec City, Canada;
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Chen X, Xu J, Yang L, Yuan Z, Xiao S, Zhang Y, Liang C, He M, Guo Y. Production of C4 and C5 branched-chain alcohols by engineered Escherichia. coli. J Ind Microbiol Biotechnol 2015; 42:1473-9. [PMID: 26350079 DOI: 10.1007/s10295-015-1656-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 07/22/2015] [Indexed: 11/26/2022]
Abstract
Higher alcohols, longer chain alcohols, contain more than 3 carbon atoms, showed close energy advantages as gasoline, and were considered as the next generation substitution for chemical fuels. Higher alcohol biosynthesis by native microorganisms mainly needs gene expression of heterologous keto acid decarboxylase and alcohol dehydrogenases. In the present study, branched-chain α-keto acid decarboxylase gene from Lactococcus lactis subsp. lactis CICC 6246 (Kivd) and alcohol dehydrogenases gene from Zymomonas mobilis CICC 41465 (AdhB) were transformed into Escherichia coli for higher alcohol production. SDS-PAGE results showed these two proteins were expressed in the recombinant strains. The resulting strain was incubated in LB medium at 37 °C in Erlenmeyer flasks and much more 3-methyl-1-butanol (104 mg/L) than isobutanol (24 mg/L) was produced. However, in 5 g/L glucose-containing medium, the production of two alcohols was similar, 156 and 161 mg/L for C4 (isobutanol) and C5 (3-methyl-1-butanol) alcohol, respectively. Effects of fermentation factors including temperature, glucose content, and α-keto acid on alcohol production were also investigated. The increase of glucose content and the adding of α-keto acids facilitated the production of C4 and C5 alcohols. The enzyme activities of pure Kivd on α-ketoisovalerate and α-ketoisocaproate were 26.77 and 21.24 μmol min(-1) mg(-1), respectively. Due to its ability on decarboxylation of α-ketoisovalerate and α-ketoisocaproate, the recombinant E. coli strain showed potential application on isoamyl alcohol and isobutanol production.
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Affiliation(s)
- Xiaoyan Chen
- Key Laboratory of Renewable Energy and Gas Hydrate, Chinese Academy of Sciences, Guangzhou, 510640, China
| | - Jingliang Xu
- Key Laboratory of Renewable Energy and Gas Hydrate, Chinese Academy of Sciences, Guangzhou, 510640, China
| | - Liu Yang
- Key Laboratory of Renewable Energy and Gas Hydrate, Chinese Academy of Sciences, Guangzhou, 510640, China
| | - Zhenhong Yuan
- Key Laboratory of Renewable Energy and Gas Hydrate, Chinese Academy of Sciences, Guangzhou, 510640, China.
| | - Shiyuan Xiao
- Key Laboratory of Renewable Energy and Gas Hydrate, Chinese Academy of Sciences, Guangzhou, 510640, China
| | - Yu Zhang
- Key Laboratory of Renewable Energy and Gas Hydrate, Chinese Academy of Sciences, Guangzhou, 510640, China
| | - Cuiyi Liang
- Key Laboratory of Renewable Energy and Gas Hydrate, Chinese Academy of Sciences, Guangzhou, 510640, China
| | - Minchao He
- Key Laboratory of Renewable Energy and Gas Hydrate, Chinese Academy of Sciences, Guangzhou, 510640, China
| | - Ying Guo
- Key Laboratory of Renewable Energy and Gas Hydrate, Chinese Academy of Sciences, Guangzhou, 510640, China
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Miryounesi M, Ghafouri-Fard S, Goodarzi H, Fardaei M. A new missense mutation in the BCKDHB gene causes the classic form of maple syrup urine disease (MSUD). J Pediatr Endocrinol Metab 2015; 28:673-5. [PMID: 25381949 DOI: 10.1515/jpem-2014-0341] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 09/29/2014] [Indexed: 11/15/2022]
Abstract
Maple syrup urine disease (MSUD) is an autosomal recessive metabolic disease caused by mutations in the BCKDHA, BCKDHB, DBT and DLD genes, which encode the E1α, E1β, E2 and E3 subunits of the branched chain α ketoacid dehydrogenase (BCKD) complex, respectively. This complex is involved in the metabolism of branched-chain amino acids. In this study, we analyzed the DNA sequences of BCKDHA and BCKDHB genes in an infant who suffered from MSUD and died at the age of 6 months. We found a new missense mutation in exon 5 of BCKDHB gene (c.508C>T). The heterozygosity of the parents for the mentioned nucleotide change was confirmed by direct sequence analysis of the corresponding segment. Another missense mutation has been found in the same codon previously and shown by in silico analyses to be deleterious. This report provides further evidence that this amino acid change can cause classic MSUD.
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26
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Shen Y, Gong X, Yan J, Qin L, Qiu G. [Maple syrup urine disease caused by two novel BCKDHB gene mutations in a Chinese neonate]. Zhonghua Er Ke Za Zhi 2015; 53:66-70. [PMID: 25748408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
OBJECTIVE Maple syrup urine disease (MSUD) is an autosomal recessive metabolic disorder that is caused by mutations in the subunits of the branched chain α-ketoacid dehydrogenase (BCKD) complex. This report presents a Han ethnic Chinese newborn infant with the severe classic form of MSUD caused by two novel missense mutations in the BCKDHB gene. METHOD The clinical and biochemical data of a Chinese neonate with classic form of MSUD were analyzed, and the DNA sequences of BCKDHA, BCKDHB, DBT and DLD genes were investigated for mutations. Then the DNA samples of the proband and the patient's parents were tested with Sanger sequencing. RESULT The manifestations of this patient were poor feeding, low reaction, and compensatory metabolic acidosis. Tandem mass spectrometry (MS/MS) showed that leucine and valine were significantly higher than normal. Urine gas chromatography-mass spectrometry (GC/MS) showed significant abnormality. Brain CT scan showed white matter changes. We identified two previously unreported mutations in the BCKDHB gene, p.Leu194Phe (c.580 C>T) and p.Ser199Arg (c.597 T>G) in exon 5. Segregation analysis showed that the novel mutation p.Ser199Arg was maternally inherited and the novel mutation p.Leu194Phe was paternally inherited. Neither mutation was found in the 186 alleles of 93 normal Han ethnic Chinese individuals. In human BCKDHB protein crystal structure, the 194th and 199th amino acids changes are likely to affect the spatial structure of the protein. The 194th and 199th amino acid of human BCKDHB protein was conserved among species. PolyPhen protein function prediction indicated that the 194th and 199th amino acid changes were likely to affect protein function. CONCLUSION Two novel missense mutations were identified in the BCKDHB gene in the Chinese patient with MSUD.
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Affiliation(s)
- Yunlin Shen
- Shanghai Children's Hospital, Shanghai Jiao Tong University, Shanghai 200040, China
| | - Xiaohui Gong
- Shanghai Children's Hospital, Shanghai Jiao Tong University, Shanghai 200040, China
| | - Jingbin Yan
- Shanghai Children's Hospital, Shanghai Jiao Tong University, Shanghai 200040, China
| | - Li Qin
- Shanghai Children's Hospital, Shanghai Jiao Tong University, Shanghai 200040, China
| | - Gang Qiu
- Shanghai Children's Hospital, Shanghai Jiao Tong University, Shanghai 200040, China.
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27
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Abstract
Lipoate is a covalently bound cofactor essential for five redox reactions in humans: in four 2-oxoacid dehydrogenases and the glycine cleavage system (GCS). Two enzymes are from the energy metabolism, α-ketoglutarate dehydrogenase and pyruvate dehydrogenase; and three are from the amino acid metabolism, branched-chain ketoacid dehydrogenase, 2-oxoadipate dehydrogenase, and the GCS. All these enzymes consist of multiple subunits and share a similar architecture. Lipoate synthesis in mitochondria involves mitochondrial fatty acid synthesis up to octanoyl-acyl-carrier protein; and three lipoate-specific steps, including octanoic acid transfer to glycine cleavage H protein by lipoyl(octanoyl) transferase 2 (putative) (LIPT2), lipoate synthesis by lipoic acid synthetase (LIAS), and lipoate transfer by lipoyltransferase 1 (LIPT1), which is necessary to lipoylate the E2 subunits of the 2-oxoacid dehydrogenases. The reduced form dihydrolipoate is reactivated by dihydrolipoyl dehydrogenase (DLD). Mutations in LIAS have been identified that result in a variant form of nonketotic hyperglycinemia with early-onset convulsions combined with a defect in mitochondrial energy metabolism with encephalopathy and cardiomyopathy. LIPT1 deficiency spares the GCS, and resulted in a combined 2-oxoacid dehydrogenase deficiency and early death in one patient and in a less severely affected individual with a Leigh-like phenotype. As LIAS is an iron-sulphur-cluster-dependent enzyme, a number of recently identified defects in mitochondrial iron-sulphur cluster synthesis, including NFU1, BOLA3, IBA57, GLRX5 presented with deficiency of LIAS and a LIAS-like phenotype. As in DLD deficiency, a broader clinical spectrum can be anticipated for lipoate synthesis defects depending on which of the affected enzymes is most rate limiting.
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Affiliation(s)
- Johannes A Mayr
- Department of Paediatrics, Paracelsus Medical University Salzburg, Salzburg, 5020, Austria,
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Hou JW, Hwang TL. Different gene preferences of maple syrup urine disease in the aboriginal tribes of Taiwan. Pediatr Neonatol 2014; 55:213-7. [PMID: 24268812 DOI: 10.1016/j.pedneo.2013.09.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 08/27/2013] [Accepted: 09/23/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Maple syrup urine disease (MSUD) is a rare inborn error of metabolism caused by a deficiency of the branched-chain α-ketoacid dehydrogenase (BCKD) complex. Mutations in any one of the three different genes encoding for the BCKD components, namely, BCKDHA, BCKDHB, and DBT, may be responsible for this disease. In Taiwan, few MSUD cases were diagnosed clinically, and most of these patients are from Aboriginal tribes. MATERIALS AND METHODS To identify and detect the carrier frequency of MSUD in Taiwanese Aboriginal tribes, we performed biochemical and molecular studies from peripheral blood in MSUD patients and dried blood on filter paper in the enrolled screened populations. RESULTS Homozygous A208T and I281T of BCKDHA were found in two patients from Hans (non-Aboriginal Taiwanese), respectively; compound heterozygous mutations of the DBT gene [4.7 kb deletion/c.650-651insT (L217F or L217fsX223) and c.650-651insT/c.88-89delAT] were found in two patients from Amis, respectively, after direct DNA sequencing and polymerase chain reaction-restriction fragment length polymorphism studies. There were no cases of deleted 4.7-kb heterozygote out of 302 normal people (Hans, n = 125; Atayal, n = 156; and Saisiyat, n = 21); by contrast, the DBT mutations c.650-651insT and deleted 4.7-kb heterozygote were noted in 2/121 and 1/121, respectively, from the general population of the Amis, a southeastern Taiwanese tribe. CONCLUSION Although the Taiwanese Austronesian Aboriginal tribes are considered to share a common origin, different gene preferences of MSUD were noted. The novel DBT mutation c.650-651insT was more prevalent than the deleted 4.7-kb heterozygote in the Amis population. The reported 4.7-kb deletion indicating a possible founder mutation may be preserved in the southern and eastern, but not in northern Aboriginal tribes of Taiwan.
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Affiliation(s)
- Jia-Woei Hou
- Department of Pediatrics, Cathay General Hospital, Taipei, Taiwan; Department of Pediatrics, Fu-Jen Catholic University School of Medicine, New Taipei City, Taiwan.
| | - Tsann-Long Hwang
- Department of Surgery, Chang Gung University School of Medicine, Taoyuan, Taiwan
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Mroch A, Davis-Keppen L, Matthes C, Stein Q. Identification of a founder mutation for maple syrup urine disease in Hutterites. S D Med 2014; 67:141-143. [PMID: 24791375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Maple syrup urine disease (MSUD) is an organic acidemia detected on newborn screening. The condition has been reported with increased frequency in certain founder populations including Hutterites. We present a case of MSUD in a Hutterite boy. Mutation analysis was completed and identified a candidate founder mutation in the BCKDHB gene, specifically c.595_596delAG. Further testing of other Hutterites with MSUD is needed to determine whether additional mutations may exist.
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Narayanan MP, Menon KN, Vasudevan DM. Analysis of gene mutations among South Indian patients with maple syrup urine disease: identification of four novel mutations. Indian J Biochem Biophys 2013; 50:442-446. [PMID: 24772966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Maple syrup urine disease (MSUD) is predominantly caused by mutations in the BCKDHA, BCKDHB and DBT genes, which encode for the E1alpha, E1beta and E2 subunits of the branched-chain alpha-keto acid dehydrogenase complex, respectively. Because disease causing mutations play a major role in the development of the disease, prenatal diagnosis at gestational level may have significance in making decisions by parents. Thus, this study was aimed to screen South Indian MSUD patients for mutations and assess the genotype-phenotype correlation. Thirteen patients diagnosed with MSUD by conventional biochemical screening such as urine analysis by DNPH test, thin layer chromatography for amino acids and blood amino acid quantification by HPLC were selected for mutation analysis. The entire coding regions of the BCKDHA, BCKDHB and DBT genes were analyzed for mutations by PCR-based direct DNA sequencing. BCKDHA and BCKDHB mutations were seen in 43% of the total ten patients, while disease-causing DBT gene mutation was observed only in 14%. Three patients displayed no mutations. Novel mutations were c.130C>T in BCKDHA gene, c. 599C>T and c.121_122delAC in BCKDHB gene and c.190G>A in DBT gene. Notably, patients harbouring these mutations were non-responsive to thiamine supplementation and other treatment regimens and might have a worse prognosis as compared to the patients not having such mutations. Thus, identification of these mutations may have a crucial role in the treatment as well as understanding the molecular mechanisms in MSUD.
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Abstract
Liver transplantation appears to be quite beneficial for treatment of maple syrup urine disease (MSUD, an inherited disorder of branched chain amino acid metabolism); however, there is a limited availability of donor livers worldwide and the first year costs of liver transplants are quite high. Recent studies have suggested that intact adipose tissue, already widely used in reconstructive surgery, may have an underappreciated high capacity for branched chain amino acid (BCAA) metabolism. Here we examined the potential for adipose tissue transplant to lower circulating BCAAs in two models of defective BCAA metabolism, BCATm and PP2Cm [branched chain keto acid dehydrogenase complex (BCKDC) phosphatase] knockout (KO) mice. After 1-2g fat transplant, BCATm and PP2Cm KO mice gained or maintained body weight 3weeks after surgery and consumed similar or more food/BCAAs the week before phlebotomy. Transplant of fat into the abdominal cavity led to a sterile inflammatory response and nonviable transplanted tissue. However when 1-2g of fat was transplanted subcutaneously into the back, either as small (0.1-0.3g) or finely minced pieces introduced with an 18-ga. needle, plasma BCAAs decreased compared to Sham operated mice. In two studies on BCATm KO mice and one study on PP2Cm KO mice, fat transplant led to 52-81% reductions in plasma BCAAs compared to baseline plasma BCAA concentrations of untreated WT type siblings. In PP2Cm KO mice, individual BCAAs in plasma were also significantly reduced by fat transplant, as were the alloisoleucine/Phe ratios. Therefore, subcutaneous fat transplantation may have merit as an adjunct to dietary treatment of MSUD. Additional studies are needed to further refine this approach.
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Affiliation(s)
- Heather A. Zimmerman
- Department of Comparative Medicine, Penn State University College of Medicine, 500 University Dr., Hershey, PA 17033, USA
| | - Kristine C. Olson
- Department of Cellular and Molecular Physiology, Penn State University College of Medicine, 500 University Dr., Hershey, PA 17033, USA
| | - Gang Chen
- Department of Public Health Sciences, Penn State University College of Medicine, 500 University Dr., Hershey, PA 17033, USA
- The Macromolecular Core Facility, Penn State University College of Medicine, 500 University Dr., Hershey, PA 17033, USA
| | - Christopher J. Lynch
- Department of Cellular and Molecular Physiology, Penn State University College of Medicine, 500 University Dr., Hershey, PA 17033, USA
- Correspondence: Christopher J. Lynch, Ph.D., Dept. of Cellular & Molecular Physiology, Penn State College of Medicine. 500 University Drive, MC-H166, Hershey, PA 17033, USA FAX: +1 717 531 7667,
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Ali EZ, Yunus ZM, Desa NM, Hock NL. Identification of a novel homozygous mutation (S144I) in a Malay patient with maple syrup urine disease. J Pediatr Endocrinol Metab 2013; 26:975-80. [PMID: 23729548 DOI: 10.1515/jpem-2012-0424] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2012] [Accepted: 04/04/2013] [Indexed: 11/15/2022]
Abstract
Maple syrup urine disease (MSUD) is a rare autosomal recessive metabolic disorder of branched-chain amino acid metabolism caused by the defective function of branched-chain α-ketoacid dehydrogenase complex (BCKDH). It is characterised by increased plasma leucine, isoleucine, and valine levels, and mutations can be detected in any one of the BCKDHA, BCKDHB, and DBT genes. In this study, we describe the molecular basis of a novel mutation found in one MSUD Malay patient from consanguineous parents. A homozygous mutation has been detected in this patient whose both parents carried a heterozygous mutation at DNA coding region c.431G>T in exon 4, which resulted in a substitution of serine to isoleucine at codon 144 (p.S144I). In silico analysis predicted S144I to be potentially damaging. The mutation was located on the alpha helical region of the BCKDHA protein, and it is predicted to affect the stability of protein due to the loss of various polar interactions between local secondary structures. Homology analysis revealed that this mutation occurred in a highly conserved region (100%). This result indicates that S144I mutation is likely pathogenic and may contribute to the classic form of MSUD in this patient.
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Abstract
Inborn errors of metabolism underlying some cases of autism present possibilities for prevention and treatment
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Affiliation(s)
- Arthur L Beaudet
- Department of Human and Molecular Genetics, Baylor College of Medicine, Houston, TX 77030, USA.
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Yang N, Han L, Gu X, Ye J, Qiu W, Zhang H, Gong Z, Zhang Y. Analysis of gene mutations in Chinese patients with maple syrup urine disease. Mol Genet Metab 2012; 106:412-8. [PMID: 22727569 DOI: 10.1016/j.ymgme.2012.05.023] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Accepted: 05/29/2012] [Indexed: 11/19/2022]
Abstract
OBJECTIVE Maple syrup urine disease (MSUD) is predominantly caused by mutations in the BCKDHA, BCKDHB and DBT genes, which encode for the E1α, E1β and E2 subunits of the branched-chain α-keto acid dehydrogenase complex, respectively. The aim of this study was to screen DNA samples from 16 Chinese MSUD patients and assess a potential correlation between genotype and phenotype. METHODS BCKDHA, BCKDHB and DBT genes were analyzed by polymerase chain reaction (PCR) and direct sequencing. Segments bearing novel mutations were identified by PCR-restriction fragment length polymorphism (PCR-RFLP) analysis. RESULTS Within the variant alleles, 28 mutations (28/32, 87.5%), were detected in 15 patients, while one patient displayed no mutations. Mutations were comprised of 20 different: 6 BCKDHA gene mutations in 4 cases, 10 BCKDHB gene mutations in 8 cases and 4 DBT gene mutations in 3 cases. From these, 14 were novel, which included 3 mutations in the BCKDHA gene, 7 in the BCKDHB gene and 4 in the DBT gene. Only two patients with mutations in the BCKDHB and DBT genes were thiamine-responsive and presented a better clinical outcome. CONCLUSION We identified 20 different mutations within the BCKDHA, BCKDHB and DBT genes among 16 Chinese MSUD patients, including 14 novel mutations. The majority were non-responsive to thiamine, associating with a worse clinical outcome. Our data provide the basis for further genotype-phenotype correlation studies in these patients, which will be beneficial for early diagnosis and in directing the approach to clinical intervention.
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Affiliation(s)
- Nan Yang
- Department of Pediatric Endocrinology, Genetic and Metabolic Disease, Shanghai Institute of Pediatric Research, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200092, China
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Park HD, Lee DH, Hong YH, Kang DH, Lee YK, Song J, Lee SY, Kim JW, Ki CS, Lee YW. Three Korean patients with maple syrup urine disease: four novel mutations in the BCKDHA gene. Ann Clin Lab Sci 2011; 41:167-173. [PMID: 21844576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Maple syrup urine disease (MSUD) is a rare, autosomal recessive disorder of branched-chain amino acid (BCAA) metabolism caused by dysfunction of the multienzyme branched-chain alpha-ketoacid dehydrogenase (BCKDH) complex. Although a few cases of MSUD have been reported in the Korean population, the genetic background of MSUD is not well understood. In this study, we investigated three newborn males who were diagnosed with MSUD using a standard newborn screening test and amino acid analysis. We screened all coding regions of the BCKDHA, BCKDHB and DBT genes for abnormalities using direct sequencing. Changes in these genes are associated with MSUD. For one patient with complex deletion/duplication mutations, we also performed TOPO TA cloning sequencing. Amino acid analysis showed elevated levels of all branched chain amino acids (BCAAs) in all patients. Three patients were either homozygous or compound heterozygous for the BCKDHA mutations. Patient 1 was homozygous for c.1036C>T (p.R346C); patient 2 was heterozygous, with c.632C>T (p.T211M) and c.659C>T (p.A220V); and patient 3 had c.1204_1209dupAAACCC (p.L402_P403dup) and c.1280_1282delTGG (p.L427_A428delinsP). Among these mutations, c.1036C>T, c.632C>T, c.1204_1209dup and c.1280_1282del were novel. These patients had no mutations in either the BCKDHB or the DBT gene. Although this study included only three patients, the five different mutations in these patients may indicate mutational heterogeneity in Korean patients with MSUD. In addition, the BCHDHA gene may present a primary target for clinical genetic analysis. To the best of our knowledge, this is the first report of genetically confirmed MSUD in Korea.
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Affiliation(s)
- Hyung-Doo Park
- Department of Laboratory Medicine & Genetics, Samsung Medical Center, Sungkyunkwan, University School of Medicine, 50 Irwon-Dong, Gangnam-Gu, Seoul, Korea
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Fernández-Guerra P, Navarrete R, Weisiger K, Desviat LR, Packman S, Ugarte M, Rodríguez-Pombo P. Functional characterization of the novel intronic nucleotide change c.288+9C>T within the BCKDHA gene: understanding a variant presentation of maple syrup urine disease. J Inherit Metab Dis 2010; 33 Suppl 3:S191-8. [PMID: 20431954 DOI: 10.1007/s10545-010-9077-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2010] [Revised: 02/25/2010] [Accepted: 03/08/2010] [Indexed: 11/26/2022]
Abstract
Mutations in any of the three different genes--BCKDHA, BCKDHB, and DBT--encoding for the E1α, E1β, and E2 catalytic components of the branched-chain α-ketoacid dehydrogenase complex can cause maple syrup urine disease (MSUD). Disease severity ranges from the classic to the mildest variant types and precise genotypes, mostly based on missense mutations, have been associated to the less severe presentations of the disease. Herein, we examine the consequences at the messenger RNA (mRNA) level of the novel intronic alteration c.288+9C>T found in heterozygous fashion in a BCKDHA variant MSUD patient who also carries the nucleotide change c.745G>A (p.Gly249Ser), previously described as a severe change. Direct analysis of the processed transcripts from the patient showed--in addition to a low but measurable level of normal mRNA product--an aberrantly spliced mRNA containing a 7-bp fragment of intron 2, which could be rescued when the patient's cells were treated with emetine. This aberrant transcript with a premature stop codon would be unstable, supporting the possible activation of nonsense-mediated mRNA decay pathway. Consistent with this finding, minigene splicing assays demonstrated that the point mutation c.288+9C>T is sufficient to create a cryptic splice site and cause the observed 7-bp insertion. Furthermore, our results strongly suggest that the c.288+9C>T allele in the patient generates both normal and aberrant transcripts that could sustain the variant presentation of the disease, highlighting the importance of correct genotyping to establish genotype-phenotype correlations and as basis for the development of therapeutic interventions.
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Affiliation(s)
- Paula Fernández-Guerra
- Centro de Diagnóstico de Enfermedades Moleculares, Dpto Biol Mol., Centro Biología Molecular-SO UAM-CSIC, Universidad Autónoma de Madrid, Campus Cantoblanco, F Ciencias Modulo 10, 28049, Madrid, Spain
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Tammachote R, Tongkobpetch S, Desudchit T, Suphapeetiporn K, Shotelersuk V. Prenatal diagnosis of a novel mutation, c.529C>T (p.Q177X), in the BCKDHA gene in a family with maple syrup urine disease. J Inherit Metab Dis 2009; 32 Suppl 1:S33-6. [PMID: 19240989 DOI: 10.1007/s10545-009-1022-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2008] [Revised: 12/19/2008] [Accepted: 01/12/2009] [Indexed: 10/21/2022]
Abstract
Maple syrup urine disease (MSUD) is an autosomal recessive metabolic disorder caused by defective activity of the branched-chain alpha-keto-acid dehydrogenase (BCKD) complex. The disease-causing mutations can affect the BCKDHA, BCKDHB or DBT genes encoding for the E1a, E1b, and E2 subunits, respectively, of the BCKD complex. Here we report a girl who first presented to our clinic at 4 years of age with profound mental retardation. A diagnosis of MSUD was subsequently made based on the results of plasma amino acid analysis. Mutation analysis confirmed that she was homozygous for a novel mutation, c.529C>T (p.Q177X) in BCKDHA, while both parents, who were first cousins, were heterozygous. This enabled us to give an option of prenatal diagnosis to the parents. The prenatal testing for MSUD was performed during the mother's subsequent pregnancy and revealed that the fetus was heterozygous for the mutation. The healthy male neonate was born and his genotype was tested by restriction enzyme analysis, which confirmed the result of the prenatal testing. In summary, a late diagnosis of MSUD in patients without an unusual odour could occur especially in countries without neonatal screening programs as seen in the index patient. Mutation detection was, however, still beneficial to the family since prenatal testing could be performed in subsequent pregnancies. In addition, a novel mutation was found, expanding the mutation spectrum of this disease.
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Affiliation(s)
- R Tammachote
- Department of Botany, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
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Liu GY, Gao SZ. Molecular cloning, sequence identification and tissue expression profile of three novel sheep (Ovis aries) genes - BCKDHA, NAGA and HEXA. Biol Res 2009; 42:69-77. [PMID: 19621134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023] Open
Abstract
The complete coding sequences of three sheep genes- BCKDHA, NAGA and HEXA were amplified using the reverse transcriptase polymerase chain reaction (RT-PCR), based on the conserved sequence information of the mouse or other mammals. The nucleotide sequences of these three genes revealed that the sheep BCKDHA gene encodes a protein of 313 amino acids which has high homology with the BCKDHA gene that encodes a protein of 447 amino acids that has high homology with the Branched chain keto acid dehydrogenase El, alpha polypeptide (BCKDHA) of five species chimpanzee (93%), human (96%), crab-eating macaque (93%), bovine (98%) and mouse (91%). The sheep NAGA gene encodes a protein of 411 amino acids that has high homology with the alpha-N-acetylgalactosaminidase (NAGA) of five species human (85%), bovine (94%), mouse (91%), rat (83%) and chicken (74%). The sheep HEXA gene encodes a protein of 529 amino acids that has high homology with the hexosaminidase A(HEXA) of five species bovine (98%), human (84%), Bornean orangután (84%), rat (80%) and mouse (81%). Finally these three novel sheep genes were assigned to GenelDs: 100145857, 100145858 and 100145856. The phylogenetic tree analysis revealed that the sheep BCKDHA, NAGA, and HEXA all have closer genetic relationships to the BCKDHA, NAGA, and HEXA of bovine. Tissue expression profile analysis was also carried out and results revealed that sheep BCKDHA, NAGA and HEXA genes were differentially expressed in tissues including muscle, heart, liver, fat, kidney, lung, small and large intestine. Our experiment is the first to establish the primary foundation for further research on these three sheep genes.
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Affiliation(s)
- G Y Liu
- Yunnan Agricultural University, Kunming, China.
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Abstract
Maple syrup urine disease (MSUD) is an inherited aminoacidopathy resulting from dysfunction of the branched-chain keto acid dehydrogenase (BCKDH) complex. This disease is currently treated primarily by dietary restriction of branched-chain amino acids (BCAAs). However, dietary compliance is often challenging. Conversely, liver transplantation significantly improves outcomes, but donor organs are scarce and there are high costs and potential risks associated with this invasive procedure. Therefore, improved treatment options for MSUD are needed. Development of novel treatments could be facilitated by animal models that accurately mimic the human disease. Animal models provide a useful system in which to explore disease mechanisms and new preclinical therapies. Here we review MSUD and currently available animal models and their corresponding relevance to the human disorder. Using animal models to gain a more complete understanding of the pathophysiology behind the human disease may lead to new or improved therapies to treat or potentially cure the disorder.
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Affiliation(s)
- K J Skvorak
- Graduate Program in the Department of Molecular Genetics and Biochemistry, University of Pittsburgh, Pittsburgh, PA, USA.
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Gorzelany K, Dursun A, Coşkun T, Kalkanoğlu-Sivri SH, Gökçay GF, Demirkol M, Feyen O, Wendel U. Molecular genetics of maple syrup urine disease in the Turkish population. Turk J Pediatr 2009; 51:97-102. [PMID: 19480318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
In maple syrup urine disease (MSUD), disease-causing mutations can affect the BCKDHA, BCKDHB or DBT genes encoding for the E1alpha, E1beta and E2 subunits of the multienzyme branched-chain alpha-keto acid dehydrogenase (BCKDH) complex. Here we summarize the MSUD genotypes of a cohort of 32 unrelated Turkish patients in whom both alleles at a single gene locus harbored presumable disease-causing nucleotide changes. The patients had different forms of MSUD, ranging from the severe classical form (26 patients) to severe and mild variants (6 patients). In all except two patients (92%), the mutations occurred homozygously. The mutational spectrum included 27 different sequence variations--12 changes in the BCKDHA, 10 in the BCKDHB, and 5 in the DBT genes. In 37% (12 patients) of a total of 64 alleles, the supposed disease-causing mutations were located in the BCKDHA gene, in 44% (14 patients) in the BCKDHB gene and in 19% (6 patients) in the DBT gene. The mutational profile is heterogeneous, although two mutations occurred three times and five mutations occurred twice. There was no cluster for a single mutation except for c.773G>A (p.Cys258Tyr) in the BCKDHA gene, a hypothetical founder mutation in the Camlidere population.
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Affiliation(s)
- Kerstin Gorzelany
- Department of General Pediatrics, Heinrich-Heine University, Düsseldorf, Germany
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Quental S, Martins E, Vilarinho L, Amorim A, João Prata M. Maple syrup urine disease due to a new large deletion at BCKDHA caused by non-homologous recombination. J Inherit Metab Dis 2008; 31 Suppl 2:S457-60. [PMID: 19085071 DOI: 10.1007/s10545-008-1046-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Revised: 10/22/2008] [Accepted: 10/24/2008] [Indexed: 11/24/2022]
Abstract
Maple syrup urine disease (MSUD) is a rare disorder of branched-chain amino acid (BCAA) metabolism caused by the defective function of branched-chain α-ketoacid dehydrogenase complex (BCKD). Many MSUD-causing mutations have already been described in genes that encode the complex (BCKDHA, BCKDHB and DBT), but up to now only four large deletions are known, all located in the DBT gene. In a previous study we identified a Portuguese MSUD patient with a homozygous deletion of exons 2, 3 and 4 at the BCKDHA gene; however, the corresponding breakpoints and, consequently, the exact deletion extension were not identified. Here, using long-range PCR and sequencing methodologies we were able to refine the characterization of this gross rearrangement. A genomic DNA loss of about 13.8 kb was detected, starting at intron 1 and ending at intron 4, thus encompassing exons 2, 3 and 4. Molecular characterization showed that the deletion junction contained a short sequence whose motif was CGGG. Since this motif is present in introns 1 and 4 of normal genomic DNA, we have hypothesized that non-homologous recombination was the mechanism underlying the identified large deletion, within which the CGGG could be derived either from intron 1 or from intron 4.
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Affiliation(s)
- S Quental
- IPATIMUP - Institute of Pathology and Molecular Immunology of University of Porto, Rua Dr Roberto Frias s/n, 4200-465, Porto, Portugal.
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Quental S, Macedo-Ribeiro S, Matos R, Vilarinho L, Martins E, Teles EL, Rodrigues E, Diogo L, Garcia P, Eusébio F, Gaspar A, Sequeira S, Furtado F, Lança I, Amorim A, Prata MJ. Molecular and structural analyses of maple syrup urine disease and identification of a founder mutation in a Portuguese Gypsy community. Mol Genet Metab 2008; 94:148-56. [PMID: 18378174 DOI: 10.1016/j.ymgme.2008.02.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2008] [Accepted: 02/14/2008] [Indexed: 11/23/2022]
Abstract
Maple syrup urine disease (MSUD) is an autosomal recessive disorder, caused by the defective function of the branched-chain alpha-ketoacid dehydrogenase complex (BCKD). BCKD is a mitochondrial complex, encoded by four nuclear genes (BCKDHA, BCKDHB, DBT and DLD), involved in the metabolism of branched-chain amino acids (BCAAs). Since the MSUD mutational spectrum has not been previously assessed in Portugal, in this study we present the molecular characterization of 30 MSUD Portuguese patients. Seventeen putative mutations have been identified (six in BCKDHA, five in BCKDHB and six in DBT); seven of them are here described for the first time. The most common mutation identified was a C deletion in BCKDHA gene (c.117delC; p.R40GfsX23), already reported in the Spanish population. Interestingly, it was found in all patients of a Gypsy community from South of the country, so a founder effect is probably responsible for the high incidence of the disease in this community. Structural models of MSUD missense mutations have been performed to understand their pathogenic effect, in order to elucidate and often to predict the severity of a mutation clinical consequence.
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Affiliation(s)
- Sofia Quental
- IPATIMUP-Institute of Pathology and Molecular Immunology of University of Porto, Rua Dr. Roberto Frias, s/n, 4200-465 Porto, Portugal.
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Flaschker N, Feyen O, Fend S, Simon E, Schadewaldt P, Wendel U. Description of the mutations in 15 subjects with variant forms of maple syrup urine disease. J Inherit Metab Dis 2007; 30:903-9. [PMID: 17922217 DOI: 10.1007/s10545-007-0579-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2007] [Revised: 08/23/2007] [Accepted: 09/13/2007] [Indexed: 11/24/2022]
Abstract
BACKGROUND In maple syrup urine disease (MSUD), disease-causing mutations can affect the BCKDHA, BCKDHB or DBT genes encoding for the E1 alpha, E1 beta and E2 subunits of the multienzyme branched-chain 2-keto acid dehydrogenase (BCKD) complex. AIM The aim of this study was to screen DNA samples of 15 subjects with distinct well-characterized variant MSUD phenotypes for mutations in the three genes in order to demonstrate a potential correlation between specific nucleotide changes and particular variant phenotypes. METHODS The exonic coding sequences of all three genes were studied using genomic DNA and cellular RNA derived from peripheral blood leukocytes. RESULTS In 37% of the cases (total 30 alleles), disease-causing mutations were located in the BCKDHA, in 46% in the BCKDHB, and in 13% in the DBT gene. Novel mutations occurring homozygously were p.Ala328Thr in the BCKDHA gene and p.Gly249_Lys257del in the DBT gene. Both are associated with a mild MSUD variant. The same holds true for the novel mutations p.Pro200Ala in BCKDHB and p.Phe307Ser in DBT which were identified in heterozygous fashion. Among the known mutant alleles, p.Gly278Ser in the BCKDHB gene was relatively frequent and also associated with a mild MSUD variant. CONCLUSION The results of this study indicate that genotyping may be predictive of clinical severity of variant MSUD phenotypes and might be of prognostic value particularly in subjects with variant MSUD identified in newborn screening in whom early treatment fortunately slows the natural course of the disease.
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Affiliation(s)
- N Flaschker
- Department of General Paediatrics, University Children's Hospital, Heinrich-Heine-University, Düsseldorf, Germany
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Kang H, Lee SK, Cho SW, Lee SH, Kwack K. Branched chain alpha-keto acid dehydrogenase, E1-beta subunit gene is associated with premature ovarian failure. Fertil Steril 2007; 89:728-31. [PMID: 17524396 DOI: 10.1016/j.fertnstert.2007.03.063] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2006] [Revised: 03/05/2007] [Accepted: 03/21/2007] [Indexed: 10/23/2022]
Abstract
Genetic variants of the human branched chain alpha-keto acid dehydrogenase, E1-beta subunit (BCKDHB) gene were identified and they have been associated with premature ovarian failure (POF). Reconstructed haplotype from these variants was also associated with POF.
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Affiliation(s)
- HyunJun Kang
- Medical Genomics Laboratory, Pochon CHA University, Gyeonggi-do, Korea
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Wang X, Hu J, Price SR. Inhibition of PI3-kinase signaling by glucocorticoids results in increased branched-chain amino acid degradation in renal epithelial cells. Am J Physiol Cell Physiol 2007; 292:C1874-9. [PMID: 17229808 DOI: 10.1152/ajpcell.00617.2006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Phosphatidylinositol 3-kinase(PI3K) is a pivotal enzyme involved in the control of a variety of diverse metabolic functions. Glucocorticoids have been shown to attenuate PI3K signaling in some nonrenal cell types, raising the possibility that some physiological effects of glucocorticoids in renal cells may be achieved by a similar mechanism. Therefore, we tested whether glucocorticoids affect signaling through the insulin receptor substrate (IRS)-1/PI3K/Akt signaling cascade in LLC-PK1-GR101 renal epithelial cells. Treatment of cells with dexamethasone for 24 h: 1) suppressed IRS-1-associated PI3K activity and Akt phosphorylation, 2) increased the level of the PI3K p85 regulatory subunit but not the p110 catalytic subunit, and 3) induced the phosphorylation of IRS-1 on inhibitory Ser307. We have previously reported that glucocorticoids increase branched-chain ketoacid dehydrogenase (BCKD) activity in LLC-PK1-GR101 cells. This response was achieved, in part, by alterations in the transcription of BCKD subunits and BCKD kinase, which inactivates the enzyme complex by phosphorylation. Therefore, we tested whether inhibition of PI3K signaling would mimick glucocorticoids by increasing branched-chain amino acid degradation. Expression of a dominant negative PI3K p85 regulatory subunit (Adp85ΔiSH2) increased BCKD activity, and dexamethasone did not further stimulate enzyme activity. Inhibition of PI3K using LY-294002 increased the transcription of the BCKD E2 subunit but not the E1α subunit or BCKD kinase. Thus, glucocorticoids inhibit signaling through the IRS-1/PI3K/Akt pathway with a consequence of increased branched-chain amino acid catabolism.
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Affiliation(s)
- Xiaonan Wang
- Renal Division, Emory University, Rm. 338, Woodruff Memorial Bldg., 1639 Pierce Dr., Atlanta, GA 30322, USA
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Pulsawat N, Kitani S, Kinoshita H, Lee CK, Nihira T. Identification of the bkdAB gene cluster, a plausible source of the starter-unit for virginiamycin M production in Streptomyces virginiae. Arch Microbiol 2007; 187:459-66. [PMID: 17375285 DOI: 10.1007/s00203-007-0212-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2006] [Revised: 10/18/2006] [Accepted: 01/04/2007] [Indexed: 11/29/2022]
Abstract
The bkdAB gene cluster, which encodes plausible E1 and E2 components of the branched-chain alpha-keto acid dehydrogenase (BCDH) complex, was isolated from Streptomyces virginiae in the vicinity of a regulatory island for virginiamycin production. Gene disruption of bkdA completely abolished the production of virginiamycin M (a polyketide-peptide antibiotic), while the production of virginiamycin S (a cyclodepsipeptide antibiotic) was unaffected. Complementation of the bkdA disruptant by genome-integration of intact bkdA completely restored the virginiamycin M production, indicating that the bkdAB cluster is essential for virginiamycin M biosynthesis, plausibly via the provision of isobutyryl-CoA as a primer unit. In contrast to a feature usually seen in the Streptomyces E1 component, namely, the separate encoding of the alpha and beta subunits, S. virginiae bkdA seemed to encode the fused form of the alpha and beta subunits, which was verified by the actual catalytic activity of the fused protein in vitro using recombinant BkdA overexpressed in Escherichia coli. Supply of an additional bkdA gene under the strong and constitutive promoter ermE* in the wild-type strain of S. virginiae resulted in enhanced production of virginiamycin M, suggesting that the supply of isobutyryl-CoA is one of the rate-limiting factors in the biosynthesis of virginiamycin M.
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Affiliation(s)
- Nattika Pulsawat
- International Center for Biotechnology, Osaka University, 2-1, Yamadaoka, Suita, Osaka, 565-0871, Japan
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Cholet O, Hénaut A, Bonnarme P. Transcriptional analysis of L-methionine catabolism in Brevibacterium linens ATCC9175. Appl Microbiol Biotechnol 2007; 74:1320-32. [PMID: 17225104 DOI: 10.1007/s00253-006-0772-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2006] [Revised: 11/17/2006] [Accepted: 11/17/2006] [Indexed: 11/28/2022]
Abstract
The expression of genes possibly involved in L-methionine and lactate catabolic pathways were performed in Brevibacterium linens (ATCC9175) in the presence or absence of added L-methionine. The expression of 27 genes of 39 selected genes differed significantly in L-methionine-enriched cultures. The expression of the gene encoding L-methionine gamma-lyase (MGL) is high in L-methionine-enriched cultures and is accompanied by a dramatic increase in volatile sulfur compounds (VSC) biosynthesis. Several genes encoding alpha-ketoacid dehydrogenase and one gene encoding an acetolactate synthase were also up-regulated by L-methionine, and are probably involved in the catabolism of alpha-ketobutyrate, the primary degradation product of L-methionine to methanethiol. Gene expression profiles together with biochemical data were used to propose catabolic pathways for L-methionine in B. linens and their possible regulation by L-methionine.
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Affiliation(s)
- Orianne Cholet
- Institut National de la Recherche Agronomique, UMR Génie et Microbiologie des Procédés Alimentaires, CBAI, 78850 Thiverval-Grignon, France
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Yep A, Kenyon GL, McLeish MJ. Determinants of substrate specificity in KdcA, a thiamin diphosphate-dependent decarboxylase. Bioorg Chem 2006; 34:325-36. [PMID: 17028071 DOI: 10.1016/j.bioorg.2006.08.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2006] [Revised: 08/16/2006] [Accepted: 08/19/2006] [Indexed: 11/26/2022]
Abstract
Thiamin diphosphate-dependent decarboxylases catalyze the non-oxidative decarboxylation of 2-keto carboxylic acids. Although they display relatively low sequence similarity, and broadly different range of substrates, these enzymes show a common homotetrameric structure. Here we describe a kinetic characterization of the substrate spectrum of a recently identified member of this class, the branched chain 2-keto acid decarboxylase (KdcA) from Lactococcus lactis. In order to understand the structural basis for KdcA substrate recognition we developed a homology model of its structure. Ser286, Phe381, Val461 and Met358 were identified as residues that appeared to shape the substrate binding pocket. Subsequently, site-directed mutagenesis was carried out on these residues with a view to converting KdcA into a pyruvate decarboxylase. The results show that the mutations all lowered the Km value for pyruvate and both the S286Y and F381W variants also had greatly increased values of k(cat) with pyruvate as a substrate.
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Affiliation(s)
- Alejandra Yep
- College of Pharmacy, University of Michigan, 428 Church Street, Ann Arbor, MI 48109-1065, USA
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Abstract
Mutations in any of the three different genes BCKDHA, BCKDHB, and DBT encoding for the E1alpha, E1beta, and E2 catalytic components of the branched-chain alpha-ketoacid dehydrogenase (BCKD) complex can cause maple syrup urine disease (MSUD). The disease presents heterogeneous clinical and molecular phenotypes. Severity of the disease ranges from the classical to the mildest variant types. Here, we describe the MSUD genotypes and related phenotypes in a cohort of 33 Spanish patients. Based on complementation testing, we selected 15 patients as defective in E1beta, 10 in E1alpha, seven in E2l; one remains unclassified. 92.5% of alleles have been characterized, and the mutational spectrum includes 36 different sequence variations presumably leading to loss-of-function, 15 changes in the BCKDHA, 14 in the BCKDHB, and seven in the DBT genes. Twenty-four changes are novel. The mutational profile is heterogeneous with no prevalent sequence variations detected, except for the E1beta mutation, c.487G>T (p.Glu163X), which appears on six out of 30 disease alleles analyzed. Approximately 30% of the patients included in this study showed a variant MSUD phenotype. That included 50% of the patients identified as EIa and at least four out of seven of those selected as EII. Precise genotypes as c.[647C>T]+[889C>T] for the EIa and c.[827T>G ]+[1349C>A] for the EII appeared associated to the mildest presentations of the disease.
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Affiliation(s)
- Pilar Rodríguez-Pombo
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa CSIC-UAM, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
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Machius M, Wynn RM, Chuang JL, Li J, Kluger R, Yu D, Tomchick DR, Brautigam CA, Chuang DT. A versatile conformational switch regulates reactivity in human branched-chain alpha-ketoacid dehydrogenase. Structure 2006; 14:287-98. [PMID: 16472748 DOI: 10.1016/j.str.2005.10.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2005] [Revised: 10/18/2005] [Accepted: 10/18/2005] [Indexed: 10/25/2022]
Abstract
The dehydrogenase/decarboxylase (E1b) component of the 4 MD human branched-chain alpha-ketoacid dehydrogenase complex (BCKDC) is a thiamin diphosphate (ThDP)-dependent enzyme. We have determined the crystal structures of E1b with ThDP bound intermediates after decarboxylation of alpha-ketoacids. We show that a key tyrosine residue in the E1b active site functions as a conformational switch to reduce the reactivity of the ThDP cofactor through interactions with its thiazolium ring. The intermediates do not assume the often-postulated enamine state, but likely a carbanion state. The carbanion presumably facilitates the second E1b-catalyzed reaction, involving the transfer of an acyl moiety from the intermediate to a lipoic acid prosthetic group in the transacylase (E2b) component of the BCKDC. The tyrosine switch further remodels an E1b loop region to promote E1b binding to E2b. Our results illustrate the versatility of the tyrosine switch in coordinating the catalytic events in E1b by modulating the reactivity of reaction intermediates.
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Affiliation(s)
- Mischa Machius
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390, USA.
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