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Saha D, Pramanik A, Freville A, Siddiqui AA, Pal U, Banerjee C, Nag S, Debsharma S, Pramanik S, Mazumder S, Maiti NC, Datta S, van Ooij C, Bandyopadhyay U. Structure-function analysis of nucleotide housekeeping protein HAM1 from human malaria parasite Plasmodium falciparum. FEBS J 2024. [PMID: 39003571 DOI: 10.1111/febs.17216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2024] [Revised: 03/29/2024] [Accepted: 06/20/2024] [Indexed: 07/15/2024]
Abstract
Non-canonical nucleotides, generated as oxidative metabolic by-products, significantly threaten the genome integrity of Plasmodium falciparum and thereby, their survival, owing to their mutagenic effects. PfHAM1, an evolutionarily conserved inosine/xanthosine triphosphate pyrophosphohydrolase, maintains nucleotide homeostasis in the malaria parasite by removing non-canonical nucleotides, although structure-function intricacies are hitherto poorly reported. Here, we report the X-ray crystal structure of PfHAM1, which revealed a homodimeric structure, additionally validated by size-exclusion chromatography-multi-angle light scattering analysis. The two monomeric units in the dimer were aligned in a parallel fashion, and critical residues associated with substrate and metal binding were identified, wherein a notable structural difference was observed in the β-sheet main frame compared to human inosine triphosphate pyrophosphatase. PfHAM1 exhibited Mg++-dependent pyrophosphohydrolase activity and the highest binding affinity to dITP compared to other non-canonical nucleotides as measured by isothermal titration calorimetry. Modifying the pfham1 genomic locus followed by live-cell imaging of expressed mNeonGreen-tagged PfHAM1 demonstrated its ubiquitous presence in the cytoplasm across erythrocytic stages with greater expression in trophozoites and schizonts. Interestingly, CRISPR-Cas9/DiCre recombinase-guided pfham1-null P. falciparum survived in culture under standard growth conditions, indicating its assistive role in non-canonical nucleotide clearance during intra-erythrocytic stages. This is the first comprehensive structural and functional report of PfHAM1, an atypical nucleotide-cleansing enzyme in P. falciparum.
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Affiliation(s)
- Debanjan Saha
- Division of Infectious Diseases and Immunology, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Atanu Pramanik
- Division of Structural Biology & Bioinformatics, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Aline Freville
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, UK
| | - Asim Azhar Siddiqui
- Division of Infectious Diseases and Immunology, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Uttam Pal
- Division of Structural Biology & Bioinformatics, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Chinmoy Banerjee
- Division of Infectious Diseases and Immunology, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Shiladitya Nag
- Division of Infectious Diseases and Immunology, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Subhashis Debsharma
- Division of Infectious Diseases and Immunology, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Saikat Pramanik
- Division of Infectious Diseases and Immunology, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Somnath Mazumder
- Department of Zoology, Raja Peary Mohan College, Uttarpara, India
| | - Nakul C Maiti
- Division of Structural Biology & Bioinformatics, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Saumen Datta
- Division of Structural Biology & Bioinformatics, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Christiaan van Ooij
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, UK
| | - Uday Bandyopadhyay
- Division of Infectious Diseases and Immunology, CSIR-Indian Institute of Chemical Biology, Kolkata, India
- Department of Biological Sciences, Bose Institute, Kolkata, India
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Averill JR, Lin JC, Jung J, Jung H. Novel insights into the role of translesion synthesis polymerase in DNA incorporation and bypass of 5-fluorouracil in colorectal cancer. Nucleic Acids Res 2024; 52:4295-4312. [PMID: 38416579 PMCID: PMC11077093 DOI: 10.1093/nar/gkae102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Revised: 01/12/2024] [Accepted: 02/01/2024] [Indexed: 03/01/2024] Open
Abstract
5-Fluorouracil (5-FU) is the first-line chemotherapeutic agent in colorectal cancer, and resistance to 5-FU easily emerges. One of the mechanisms of drug action and resistance of 5-FU is through DNA incorporation. Our quantitative reverse-transcription PCR data showed that one of the translesion synthesis (TLS) DNA polymerases, DNA polymerase η (polη), was upregulated within 72 h upon 5-FU administration at 1 and 10 μM, indicating that polη is one of the first responding polymerases, and the only TLS polymerase, upon the 5-FU treatment to incorporate 5-FU into DNA. Our kinetic studies revealed that 5-fluoro-2'-deoxyuridine triphosphate (5FdUTP) was incorporated across dA 41 and 28 times more efficiently than across dG and across inosine, respectively, by polη indicating that the mutagenicity of 5-FU incorporation is higher in the presence of inosine and that DNA lesions could lead to more mutagenic incorporation of 5-FU. Our polη crystal structures complexed with DNA and 5FdUTP revealed that dA:5FdUTP base pair is like dA:dTTP in the active site of polη, while 5FdUTP adopted 4-enol tautomer in the base pairs with dG and HX increasing the insertion efficiency compared to dG:dTTP for the incorrect insertions. These studies confirm that polη engages in the DNA incorporation and bypass of 5-FU.
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Affiliation(s)
- Jameson R Averill
- Division of Medicinal Chemistry, School of Pharmacy, University of Connecticut, Storrs, CT 06269, USA
| | - Jackson C Lin
- Division of Medicinal Chemistry, School of Pharmacy, University of Connecticut, Storrs, CT 06269, USA
| | - John Jung
- Division of Medicinal Chemistry, School of Pharmacy, University of Connecticut, Storrs, CT 06269, USA
| | - Hunmin Jung
- Division of Medicinal Chemistry, School of Pharmacy, University of Connecticut, Storrs, CT 06269, USA
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3
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Burgis NE, VanWormer K, Robbins D, Smith J. An ITPA Enzyme with Improved Substrate Selectivity. Protein J 2024; 43:62-71. [PMID: 38066288 PMCID: PMC10901923 DOI: 10.1007/s10930-023-10162-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/03/2023] [Indexed: 02/29/2024]
Abstract
Recent clinical data have identified infant patients with lethal ITPA deficiencies. ITPA is known to modulate ITP concentrations in cells and has a critical function in neural development which is not understood. Polymorphism of the ITPA gene affects outcomes for both ribavirin and thiopurine based therapies and nearly one third of the human population is thought to harbor ITPA polymorphism. In a previous site-directed mutagenesis alanine screen of the ITPA substrate selectivity pocket, we identified the ITPA mutant, E22A, as a gain-of function mutant with enhanced ITP hydrolysis activity. Here we report a rational enzyme engineering experiment to investigate the biochemical properties of position 22 ITPA mutants and find that the E22D ITPA has two- and four-fold improved substrate selectivity for ITP over the canonical purine triphosphates ATP and GTP, respectively, while maintaining biological activity. The novel E22D ITPA should be considered as a platform for further development of ITPA therapies.
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Affiliation(s)
- Nicholas E Burgis
- Department of Chemistry, Biochemistry & Physics, Eastern Washington University, Cheney, WA, 99004, USA.
| | - Kandise VanWormer
- Department of Chemistry, Biochemistry & Physics, Eastern Washington University, Cheney, WA, 99004, USA
| | - Devin Robbins
- Department of Chemistry, Biochemistry & Physics, Eastern Washington University, Cheney, WA, 99004, USA
| | - Jonathan Smith
- Department of Chemistry, Biochemistry & Physics, Eastern Washington University, Cheney, WA, 99004, USA
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4
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Nassogne MC, Marie S, Dewulf JP. Neurological presentations of inborn errors of purine and pyrimidine metabolism. Eur J Paediatr Neurol 2024; 48:69-77. [PMID: 38056117 DOI: 10.1016/j.ejpn.2023.11.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 11/25/2023] [Accepted: 11/30/2023] [Indexed: 12/08/2023]
Abstract
Purines and pyrimidines are essential components as they are the building blocks of vital molecules, such as nucleic acids, coenzymes, signalling molecules, as well as energy transfer molecules. Purine and pyrimidine metabolism defects are characterised by abnormal concentrations of purines, pyrimidines and/or their metabolites in cells or body fluids. This phenomenon is due to a decreased or an increased activity of enzymes involved in this metabolism and has been reported in humans for over 60 years. This review provides an overview of neurological presentations of inborn errors of purine and pyrimidine metabolism. These conditions can lead to psychomotor retardation, epilepsy, hypotonia, or microcephaly; sensory involvement, such as deafness and visual disturbances; multiple malformations, as well as muscular symptoms. Clinical signs are often nonspecific and thus overlooked, but some diseases are treatable and early diagnosis may improve the child's future. Although these metabolic hereditary diseases are rare, they are most probably under-diagnosed. When confronted with suggestive clinical or laboratory signs, clinicians should prescribe genetic testing in association with a biochemical screening including thorough purine and pyrimidine metabolites analysis and/or specific enzyme evaluation. This is most likely going to increase the number of confirmed patients.
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Affiliation(s)
- Marie-Cécile Nassogne
- Service de Neurologie Pédiatrique, Cliniques Universitaires Saint-Luc, UCLouvain, B-1200, Brussels, Belgium; Institut des Maladies Rares, Cliniques Universitaires Saint-Luc, UCLouvain, B-1200, Brussels, Belgium.
| | - Sandrine Marie
- Laboratoire des Maladies Métaboliques Héréditaires/Biochimie Génétique et Centre de Dépistage Néonatal, Cliniques Universitaires Saint-Luc, UCLouvain, B-1200, Brussels, Belgium.
| | - Joseph P Dewulf
- Institut des Maladies Rares, Cliniques Universitaires Saint-Luc, UCLouvain, B-1200, Brussels, Belgium; Laboratoire des Maladies Métaboliques Héréditaires/Biochimie Génétique et Centre de Dépistage Néonatal, Cliniques Universitaires Saint-Luc, UCLouvain, B-1200, Brussels, Belgium.
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5
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Lopez-Schenk R, Collins NL, Schenk NA, Beard DA. Integrated Functions of Cardiac Energetics, Mechanics, and Purine Nucleotide Metabolism. Compr Physiol 2023; 14:5345-5369. [PMID: 38158366 PMCID: PMC10956446 DOI: 10.1002/cphy.c230011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
Purine nucleotides play central roles in energy metabolism in the heart. Most fundamentally, the free energy of hydrolysis of the adenine nucleotide adenosine triphosphate (ATP) provides the thermodynamic driving force for numerous cellular processes including the actin-myosin crossbridge cycle. Perturbations to ATP supply and/or demand in the myocardium lead to changes in the homeostatic balance between purine nucleotide synthesis, degradation, and salvage, potentially affecting myocardial energetics and, consequently, myocardial mechanics. Indeed, both acute myocardial ischemia and decompensatory remodeling of the myocardium in heart failure are associated with depletion of myocardial adenine nucleotides and with impaired myocardial mechanical function. Yet there remain gaps in the understanding of mechanistic links between adenine nucleotide degradation and contractile dysfunction in heart disease. The scope of this article is to: (i) review current knowledge of the pathways of purine nucleotide depletion and salvage in acute ischemia and in chronic heart disease; (ii) review hypothesized mechanisms linking myocardial mechanics and energetics with myocardial adenine nucleotide regulation; and (iii) highlight potential targets for treating myocardial metabolic and mechanical dysfunction associated with these pathways. It is hypothesized that an imbalance in the degradation, salvage, and synthesis of adenine nucleotides leads to a net loss of adenine nucleotides in both acute ischemia and under chronic high-demand conditions associated with the development of heart failure. This reduction in adenine nucleotide levels results in reduced myocardial ATP and increased myocardial inorganic phosphate. Both of these changes have the potential to directly impact tension development and mechanical work at the cellular level. © 2024 American Physiological Society. Compr Physiol 14:5345-5369, 2024.
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Affiliation(s)
- Rachel Lopez-Schenk
- Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA
| | - Nicole L Collins
- Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA
| | - Noah A Schenk
- Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA
| | - Daniel A Beard
- Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA
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6
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Omichi N, Kishita Y, Nakama M, Sasai H, Terazawa A, Kobayashi E, Fushimi T, Sugiyama Y, Ichimoto K, Nitta KR, Yatsuka Y, Ohtake A, Murayama K, Okazaki Y. Novel ITPA variants identified by whole genome sequencing and RNA sequencing. J Hum Genet 2023; 68:649-652. [PMID: 37246162 DOI: 10.1038/s10038-023-01156-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Revised: 04/20/2023] [Accepted: 04/21/2023] [Indexed: 05/30/2023]
Abstract
Approximately 80% of rare diseases have a genetic cause, and an accurate genetic diagnosis is necessary for disease management, prognosis prediction, and genetic counseling. Whole-exome sequencing (WES) is a cost-effective approach for exploring the genetic cause, but several cases often remain undiagnosed. We combined whole genome sequencing (WGS) and RNA sequencing (RNA-seq) to identify the pathogenic variants in an unsolved case using WES. RNA-seq revealed aberrant exon 4 and exon 6 splicing of ITPA. WGS showed a previously unreported splicing donor variant, c.263+1G>A, and a novel heterozygous deletion, including exon 6. Detailed examination of the breakpoint indicated the deletion caused by recombination between Alu elements in different introns. The proband was found to have developmental and epileptic encephalopathies caused by variants in the ITPA gene. The combination of WGS and RNA-seq may be effective in diagnosing conditions in proband who could not be diagnosed using WES.
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Affiliation(s)
- Nanako Omichi
- Department of Life Science, Faculty of Science and Engineering, Kindai University, Osaka, Japan
| | - Yoshihito Kishita
- Department of Life Science, Faculty of Science and Engineering, Kindai University, Osaka, Japan
- Diagnostics and Therapeutic of Intractable Diseases, Intractable Disease Research Center, Graduate School of Medicine, Juntendo University, Tokyo, Japan
| | - Mina Nakama
- Department of Life Science, Faculty of Science and Engineering, Kindai University, Osaka, Japan
- Clinical Genetics Center, Gifu University Hospital, Gifu, Japan
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu, Japan
| | - Hideo Sasai
- Clinical Genetics Center, Gifu University Hospital, Gifu, Japan
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu, Japan
- Department of Applied Genomics, Kazusa DNA Research Institute, Chiba, Japan
| | - Atsushi Terazawa
- Department of Pediatric Cardiology, Gifu Prefectural General Medical Center, Gifu, Japan
| | - Emiko Kobayashi
- Department of Pediatrics, Gifu Prefectural General Medical Center, Gifu, Japan
| | - Takuya Fushimi
- Department of Metabolism, Chiba Children's Hospital, Chiba, Japan
| | - Yohei Sugiyama
- Department of Metabolism, Chiba Children's Hospital, Chiba, Japan
| | - Keiko Ichimoto
- Department of Metabolism, Chiba Children's Hospital, Chiba, Japan
| | - Kazuhiro R Nitta
- Diagnostics and Therapeutic of Intractable Diseases, Intractable Disease Research Center, Graduate School of Medicine, Juntendo University, Tokyo, Japan
| | - Yukiko Yatsuka
- Diagnostics and Therapeutic of Intractable Diseases, Intractable Disease Research Center, Graduate School of Medicine, Juntendo University, Tokyo, Japan
| | - Akira Ohtake
- Department of Pediatrics and Clinical Genomics, Saitama Medical University, Moroyama, Saitama, Japan
- Center for Intractable Diseases, Saitama Medical University Hospital, Moroyama, Saitama, Japan
| | - Kei Murayama
- Diagnostics and Therapeutic of Intractable Diseases, Intractable Disease Research Center, Graduate School of Medicine, Juntendo University, Tokyo, Japan
- Department of Metabolism, Chiba Children's Hospital, Chiba, Japan
- Center for Medical Genetics, Chiba Children's Hospital, Chiba, Japan
| | - Yasushi Okazaki
- Diagnostics and Therapeutic of Intractable Diseases, Intractable Disease Research Center, Graduate School of Medicine, Juntendo University, Tokyo, Japan.
- Laboratory for Comprehensive Genomic Analysis, RIKEN Center for Integrative Medical Sciences, Kanagawa, Japan.
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7
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Schroader JH, Handley MT, Reddy K. Inosine triphosphate pyrophosphatase: A guardian of the cellular nucleotide pool and potential mediator of RNA function. WILEY INTERDISCIPLINARY REVIEWS. RNA 2023; 14:e1790. [PMID: 37092460 DOI: 10.1002/wrna.1790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 02/10/2023] [Accepted: 03/20/2023] [Indexed: 04/25/2023]
Abstract
Inosine triphosphate pyrophosphatase (ITPase), encoded by the ITPA gene in humans, is an important enzyme that preserves the integrity of cellular nucleotide pools by hydrolyzing the noncanonical purine nucleotides (deoxy)inosine and (deoxy)xanthosine triphosphate into monophosphates and pyrophosphate. Variants in the ITPA gene can cause partial or complete ITPase deficiency. Partial ITPase deficiency is benign but clinically relevant as it is linked to altered drug responses. Complete ITPase deficiency causes a severe multisystem disorder characterized by seizures and encephalopathy that is frequently associated with fatal infantile dilated cardiomyopathy. In the absence of ITPase activity, its substrate noncanonical nucleotides have the potential to accumulate and become aberrantly incorporated into DNA and RNA. Hence, the pathophysiology of ITPase deficiency could arise from metabolic imbalance, altered DNA or RNA regulation, or from a combination of these factors. Here, we review the known functions of ITPase and highlight recent work aimed at determining the molecular basis for ITPA-associated pathogenesis which provides evidence for RNA dysfunction. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA in Disease and Development > RNA in Development.
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Affiliation(s)
- Jacob H Schroader
- The RNA Institute, University at Albany, State University of New York, Albany, New York, USA
- Department of Biological Sciences, University at Albany, State University of New York, Albany, New York, USA
| | - Mark T Handley
- Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Kaalak Reddy
- The RNA Institute, University at Albany, State University of New York, Albany, New York, USA
- Department of Biological Sciences, University at Albany, State University of New York, Albany, New York, USA
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Heidari M, Khalili M, Balouchi F, Roozbeh J, Shamsaefar AR, Malek Hosseini SA, Karimi MH. Investigation of the Association Between ITPA Gene 94C>A Sequence Variant and Kidney Transplant Rejection in Iranian Kidney Transplant Recipients. EXP CLIN TRANSPLANT 2023; 21:652-656. [PMID: 37698399 DOI: 10.6002/ect.2023.0066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/13/2023]
Abstract
OBJECTIVES Thiopurine prodrugs are commonly used in kidney transplant recipients. Inosine triphosphate pyrophosphatase is an enzyme encoded by the ITPA gene. Alteration of ITPA gene is one of the pharmacogenetic sequence variants possibly involved in thiopurine metabolism. The ITPA 94C>A sequence variant (C-to-A substitution at nucleotide 94) is associated with an increased risk of adverse drug reactions in patients treated with the thiopurine drug. The aim of the present study was to investigate the effect of the ITPA 94C>A gene sequence variant in kidney transplant recipients. MATERIALS AND METHODS The genotyping of the ITPA rs1127354 variant was performed by the polymerase chain reaction restriction fragment length polymorphism method in 140 kidney transplant recipients and in 100 control participants. Data were analyzed with SPSS statistical software. RESULTS The results revealed a significant difference between control and nonrejection groups regarding the rs1127354 genotype and allele frequency. No significant difference was found between the rejection and nonrejection groups regarding the rs1127354 genotype and allele frequency. Also, a significant association was observed between the ageofthe control group and age of the rejection group. No significant differences between sex and underlying disease in patients with or without rejection were observed. CONCLUSIONS We observed no significant differences between rejection and nonrejection transplant. Further studies are recommended, in a larger population and with different ethnicities.
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Affiliation(s)
- Mozhdeh Heidari
- >From the Transplant Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
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Burgis NE, April C, VanWormer K. Arginine-178 is an essential residue for ITPA function. Arch Biochem Biophys 2023; 744:109700. [PMID: 37506994 PMCID: PMC10530447 DOI: 10.1016/j.abb.2023.109700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 07/18/2023] [Accepted: 07/22/2023] [Indexed: 07/30/2023]
Abstract
The inosine triphosphate pyrophosphatase (ITPA) enzyme plays a critical cellular role by removing noncanonical nucleoside triphosphates from nucleotide pools. One of the first pathological ITPA mutants identified is R178C (rs746930990), which causes a fatal infantile encephalopathy, termed developmental and epileptic encephalopathy 35 (DEE 35). The accumulation of noncanonical nucleotides such as inosine triphosphate (ITP), is suspected to affect RNA and/or interfere with normal nucleotide function, leading to development of DEE 35. Molecular dynamics simulations have shown that the very rare R178C mutation does not significantly perturb the overall structure of the protein, but results in a high level of structural flexibility and disrupts active-site hydrogen bond networks, while preliminary biochemical data indicate that ITP hydrolyzing activity is significantly reduced for the R178C mutant. Here we report Michaelis-Menten enzyme kinetics data for the R178C ITPA mutant and three other position 178 ITPA mutants. These data confirm that position 178 is essential for ITPA activity and even conservative mutation at this site (R178K) results in significantly reduced enzyme activity. Our data support that disruption of the active-site hydrogen bond network is a major cause of diminished ITP hydrolyzing activity for the R178C mutation. These results suggest an avenue for developing therapies to address DEE 35.
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Affiliation(s)
- Nicholas E Burgis
- Department of Chemistry, Biochemistry & Physics, Eastern Washington University, Cheney, WA, 99004, USA.
| | - Caitlin April
- Department of Chemistry, Biochemistry & Physics, Eastern Washington University, Cheney, WA, 99004, USA
| | - Kandise VanWormer
- Department of Chemistry, Biochemistry & Physics, Eastern Washington University, Cheney, WA, 99004, USA
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10
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Kaya Özçora GD, Söbü E, Gümüş U. Genetic and clinical variations of developmental epileptic encephalopathies. Neurol Res 2023; 45:226-233. [PMID: 36731496 DOI: 10.1080/01616412.2023.2170917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
OBJECTIVE The concept of 'developmental and epileptic encephalopathy (DEE)' recognises that in infants presenting with severe early-onset epilepsy, neurodevelopmental comorbidity may be attributable to both the underlying cause and to adverse effects of uncontrolled epileptic activity. There is no direct genotype - phenotype correlation in DEEs. This study aimed to report the genetic and phenotypic differences in patients with DEE. METHODS Genetic evaluations of the patients were performed due to epilepsy combined with developmental delay, epileptic encephalopathy, motor deficits, autistic features, or cognitive impairment. Patients were assessed for demographic characteristics, medical history, family history, psychomotor development, seizure control interventions, electroencephalogram (EEG) and magnetic resonance imaging (MRI) findings. RESULTS This study included 20 children aged 0-16 years who were diagnosed as having DEE.The types of DEE detected in our study were DEE 2, 4, 6B, 7, 11, 26, 30, 33, 35, 42, 58, 62, and 67.Status epilepticus was recorded in only DEE7. The most common EEG abnormality was multifocal epileptic discharges (35%,) followed by burst-suppression patterns in patients with neonatal-onset seizures. Thirteen of the children were aged over 2 years, two (15%) were non-ambulatory and six (46%) were non-verbal. MRI scans were normal in 80% of the patients. Refractory epilepsy seen in 33% of cases.De-novo mutation, microcephaly and dysmorphic findings accompany resistant seizures and are associated with poor prognosis. DISCUSSION For patients with movement disorders, developmental delay, autism, and ID with or without epilepsy in any period of their life, next-generation sequencing is the only diagnostic technique available, with genetic analysis often being the only diagnostic method.
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Affiliation(s)
- Gül Demet Kaya Özçora
- Faculty of Medical Sciences Pediatric Neurology Dept, Gaziantep Hasan Kalyoncu University, Gaziantep, Turkey
| | - Elif Söbü
- Kartal Dr.Lütfi Kırdar City Hospital, Department of Pediatric Endocrinology, Istanbul, Turkey
| | - Uğur Gümüş
- Dr. Ersin Arslan Education and Research Hospital, Medical Genetics Department, Gaziantep, Turkey
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11
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Schroader JH, Jones LA, Meng R, Shorrock HK, Richardson J, Shaughnessy S, Lin Q, Begley T, Berglund J, Fuchs G, Handley M, Reddy K. Disease-associated inosine misincorporation into RNA hinders translation. Nucleic Acids Res 2022; 50:9306-9318. [PMID: 35979951 PMCID: PMC9458462 DOI: 10.1093/nar/gkac709] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Revised: 07/08/2022] [Accepted: 08/06/2022] [Indexed: 12/24/2022] Open
Abstract
Failure to prevent accumulation of the non-canonical nucleotide inosine triphosphate (ITP) by inosine triphosphate pyrophosphatase (ITPase) during nucleotide synthesis results in misincorporation of inosine into RNA and can cause severe and fatal developmental anomalies in humans. While the biochemical activity of ITPase is well understood, the pathogenic basis of ITPase deficiency and the molecular and cellular consequences of ITP misincorporation into RNA remain cryptic. Here, we demonstrate that excess ITP in the nucleotide pool during in vitro transcription results in T7 polymerase-mediated inosine misincorporation in luciferase RNA. In vitro translation of inosine-containing luciferase RNA reduces resulting luciferase activity, which is only partly explained by reduced abundance of the luciferase protein produced. Using Oxford Nanopore Direct RNA sequencing, we reveal inosine misincorporation to be stochastic but biased largely towards misincorporation in place of guanosine, with evidence for misincorporation also in place of cytidine, adenosine and uridine. Inosine misincorporation into RNA is also detected in Itpa-null mouse embryonic heart tissue as an increase in relative variants compared with the wild type using Illumina RNA sequencing. By generating CRISPR/Cas9 rat H9c2 Itpa-null cardiomyoblast cells, we validate a translation defect in cells that accumulate inosine within endogenous RNA. Furthermore, we observe hindered cellular translation of transfected luciferase RNA containing misincorporated inosine in both wild-type and Itpa-null cells. We therefore conclude that inosine misincorporation into RNA perturbs translation, thus providing mechanistic insight linking ITPase deficiency, inosine accumulation and pathogenesis.
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Affiliation(s)
| | | | - Ryan Meng
- The RNA Institute, University at Albany, State University of New York, Albany, NY 12222, USA
| | - Hannah K Shorrock
- The RNA Institute, University at Albany, State University of New York, Albany, NY 12222, USA
| | - Jared I Richardson
- The RNA Institute, University at Albany, State University of New York, Albany, NY 12222, USA,Department of Biochemistry and Molecular Biology, Center for NeuroGenetics, University of Florida, Gainesville, FL 32611, USA
| | - Sharon M Shaughnessy
- The RNA Institute, University at Albany, State University of New York, Albany, NY 12222, USA
| | - Qishan Lin
- The RNA Institute, University at Albany, State University of New York, Albany, NY 12222, USA,RNA Epitranscriptomics & Proteomics Resource, University at Albany, Albany, NY 12222, USA
| | - Thomas J Begley
- The RNA Institute, University at Albany, State University of New York, Albany, NY 12222, USA,Department of Biological Sciences, University at Albany, State University of New York, Albany, NY 12222, USA,RNA Epitranscriptomics & Proteomics Resource, University at Albany, Albany, NY 12222, USA
| | - J Andrew Berglund
- The RNA Institute, University at Albany, State University of New York, Albany, NY 12222, USA,Department of Biological Sciences, University at Albany, State University of New York, Albany, NY 12222, USA,Department of Biochemistry and Molecular Biology, Center for NeuroGenetics, University of Florida, Gainesville, FL 32611, USA
| | - Gabriele Fuchs
- The RNA Institute, University at Albany, State University of New York, Albany, NY 12222, USA,Department of Biological Sciences, University at Albany, State University of New York, Albany, NY 12222, USA
| | - Mark T Handley
- Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Kaalak Reddy
- *To whom correspondence should be addressed. Tel: +1 518 442 1464;
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12
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Calame DG, Herman I, Marshall AE, Maroofian R, Donis KC, Fatih JM, Mitani T, Du H, Grochowski CM, Sousa S, Bakhtiari S, Ito YA, Rocca C, Hunter JV, Sutton VR, Emrick LT, Boycott KM, Lossos A, Fellig Y, Prus E, Kalish Y, Meiner V, Suerink M, Ruivenkamp C, Muirhead K, Saadi NW, Zaki MS, Skidmore DL, Osmond M, Silva TO, Houlden H, Murphy D, Ghayoorarimiani E, Jamshidi Y, Jaddoa AG, Tajsharghi H, Jin SC, Coban-Akdemir Z, Travaglini L, Nicita F, Jhangiani SN, Gibbs RA, Posey JE, Kruer MC, Kernohan KD, Morales Saute JA, Vanderver A, Pehlivan D, Marafi D, Lupski JR. Biallelic Variants in the Ectonucleotidase ENTPD1 Cause a Complex Neurodevelopmental Disorder with Intellectual Disability, Distinct White Matter Abnormalities, and Spastic Paraplegia. Ann Neurol 2022; 92:304-321. [PMID: 35471564 PMCID: PMC10054521 DOI: 10.1002/ana.26381] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 04/18/2022] [Accepted: 04/21/2022] [Indexed: 01/17/2023]
Abstract
OBJECTIVE Human genomics established that pathogenic variation in diverse genes can underlie a single disorder. For example, hereditary spastic paraplegia is associated with >80 genes, with frequently only few affected individuals described for each gene. Herein, we characterize a large cohort of individuals with biallelic variation in ENTPD1, a gene previously linked to spastic paraplegia 64 (Mendelian Inheritance in Man # 615683). METHODS Individuals with biallelic ENTPD1 variants were recruited worldwide. Deep phenotyping and molecular characterization were performed. RESULTS A total of 27 individuals from 17 unrelated families were studied; additional phenotypic information was collected from published cases. Twelve novel pathogenic ENTPD1 variants are described (NM 001776.6): c.398_399delinsAA; p.(Gly133Glu), c.540del; p.(Thr181Leufs*18), c.640del; p.(Gly216Glufs*75), c.185 T > G; p.(Leu62*), c.1531 T > C; p.(*511Glnext*100), c.967C > T; p.(Gln323*), c.414-2_414-1del, and c.146 A > G; p.(Tyr49Cys) including 4 recurrent variants c.1109 T > A; p.(Leu370*), c.574-6_574-3del, c.770_771del; p.(Gly257Glufs*18), and c.1041del; p.(Ile348Phefs*19). Shared disease traits include childhood onset, progressive spastic paraplegia, intellectual disability (ID), dysarthria, and white matter abnormalities. In vitro assays demonstrate that ENTPD1 expression and function are impaired and that c.574-6_574-3del causes exon skipping. Global metabolomics demonstrate ENTPD1 deficiency leads to impaired nucleotide, lipid, and energy metabolism. INTERPRETATION The ENTPD1 locus trait consists of childhood disease onset, ID, progressive spastic paraparesis, dysarthria, dysmorphisms, and white matter abnormalities, with some individuals showing neurocognitive regression. Investigation of an allelic series of ENTPD1 (1) expands previously described features of ENTPD1-related neurological disease, (2) highlights the importance of genotype-driven deep phenotyping, (3) documents the need for global collaborative efforts to characterize rare autosomal recessive disease traits, and (4) provides insights into disease trait neurobiology. ANN NEUROL 2022;92:304-321.
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Affiliation(s)
- Daniel G. Calame
- Section of Pediatric Neurology and Developmental Neuroscience, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
- Texas Children’s Hospital, Houston, Texas, 77030, USA
| | - Isabella Herman
- Section of Pediatric Neurology and Developmental Neuroscience, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
- Texas Children’s Hospital, Houston, Texas, 77030, USA
| | - Aren E. Marshall
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, K1H 8L1, Canada
| | - Reza Maroofian
- Department of Neuromuscular Disorders, Queen Square Institute of Neurology, University College London, London, UK
| | - Karina Carvalho Donis
- Graduate Program in Genetics and Molecular Biology, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
- Medical Genetics Service, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
| | - Jawid M. Fatih
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Tadahiro Mitani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Haowei Du
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
| | | | | | - Somayeh Bakhtiari
- Pediatric Movement Disorders Program, Division of Pediatric Neurology, Barrow Neurological Institute, Phoenix Children’s Hospital, Phoenix, AZ, 85016, USA
- Departments of Child Health, Neurology, and Cellular & Molecular Medicine, and Program in Genetics, University of Arizona College of Medicine–Phoenix, Phoenix, AZ, USA
| | - Yoko A. Ito
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, K1H 8L1, Canada
| | - Clarissa Rocca
- Department of Neuromuscular Disorders, Queen Square Institute of Neurology, University College London, London, UK
| | - Jill V. Hunter
- Texas Children’s Hospital, Houston, Texas, 77030, USA
- Division of Neuroradiology, Edward B. Singleton Department of Radiology, Texas Children’s Hospital, Houston, Texas
| | - V. Reid Sutton
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
- Texas Children’s Hospital, Houston, Texas, 77030, USA
| | - Lisa T. Emrick
- Section of Pediatric Neurology and Developmental Neuroscience, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
- Texas Children’s Hospital, Houston, Texas, 77030, USA
| | - Kym M. Boycott
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, K1H 8L1, Canada
| | - Alexander Lossos
- Department of Neurology, Hadassah Medical Organization and Faculty of Medicine, Hebrew University, Jerusalem 91120, Israel
| | - Yakov Fellig
- Department of Pathology, Hadassah Medical Organization and Faculty of Medicine, Hebrew University, Jerusalem 91120, Israel
| | - Eugenia Prus
- Hematology and Bone Marrow Transplantation Division, Hadassah Medical Center and the Hebrew University, POB 12000, 91120, Jerusalem, Israel
| | - Yosef Kalish
- Hematology and Bone Marrow Transplantation Division, Hadassah Medical Center and the Hebrew University, POB 12000, 91120, Jerusalem, Israel
| | - Vardiella Meiner
- Department of Genetics, Hadassah Medical Center and the Hebrew University, POB 12000, 91120, Jerusalem, Israel
| | - Manon Suerink
- Department of Clinical Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Claudia Ruivenkamp
- Department of Clinical Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Kayla Muirhead
- Division of Neurology, Children’s Hospital of Philadelphia, Abramson Research Center, 3615 Civic Center Boulevard, Philadelphia, Pennsylvania 19104, USA
| | - Nebal W. Saadi
- College of Medicine / University of Baghdad, Children Welfare Teaching Hospital, Medical City Complex, Baghdad 10001, Iraq
| | - Maha S. Zaki
- Clinical Genetics Department, Human Genetics and Genome Research Division, Centre of Excellence of Human Genetics, National Research Centre, Cairo, Egypt
| | - David L. Skidmore
- Department of Pediatrics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Matthew Osmond
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, K1H 8L1, Canada
| | - Thiago Oliveira Silva
- Medical Genetics Service, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
- Postgraduate Program in Medicine: Medical Sciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Henry Houlden
- Department of Neuromuscular Disorders, Queen Square Institute of Neurology, University College London, London, UK
| | - David Murphy
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, University College London, United Kingdom
| | - Ehsan Ghayoorarimiani
- Genetics Section, Molecular and Clinical Sciences Institute, St. George’s University of London, Cranmer Terrace, London SW17 0RE, UK
| | - Yalda Jamshidi
- Genetics Section, Molecular and Clinical Sciences Institute, St. George’s University of London, Cranmer Terrace, London SW17 0RE, UK
| | | | - Homa Tajsharghi
- School of Health Sciences, Division Biomedicine, University of Skovde, Skovde, Sweden
| | - Sheng Chih Jin
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA
| | - Zeynep Coban-Akdemir
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
- Human Genetics Center, Department of Epidemiology, Human Genetics, and Environmental Sciences, School of Public Health, The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Lorena Travaglini
- Unit of Neuromuscular and Neurodegenerative Disorders, Department of Neurosciences, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
- Laboratory of Molecular Medicine, Department of Neuroscience, IRCCS Bambino Gesù Children’s Hospital, 00146 Rome, Italy
| | - Francesco Nicita
- Unit of Neuromuscular and Neurodegenerative Disorders, Department of Neurosciences, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
- Laboratory of Molecular Medicine, Department of Neuroscience, IRCCS Bambino Gesù Children’s Hospital, 00146 Rome, Italy
| | - Shalini N. Jhangiani
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Richard A. Gibbs
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Jennifer E. Posey
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Michael C. Kruer
- Pediatric Movement Disorders Program, Division of Pediatric Neurology, Barrow Neurological Institute, Phoenix Children’s Hospital, Phoenix, AZ, 85016, USA
- Departments of Child Health, Neurology, and Cellular & Molecular Medicine, and Program in Genetics, University of Arizona College of Medicine–Phoenix, Phoenix, AZ, USA
| | - Kristin D. Kernohan
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, K1H 8L1, Canada
- Newborn Screening Ontario, Ottawa, Canada, K1H 8L1, Canada
| | - Jonas A. Morales Saute
- Medical Genetics Service, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
- Department of Pediatrics, Dalhousie University, Halifax, Nova Scotia, Canada
- Department of Internal Medicine, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
- Neurology Service, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
| | - Adeline Vanderver
- Division of Neurology, Children’s Hospital of Philadelphia, Abramson Research Center, 3615 Civic Center Boulevard, Philadelphia, Pennsylvania 19104, USA
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, 3400 Civic Center Boulevard, Philadelphia, Pennsylvania 19104, USA
| | - Davut Pehlivan
- Section of Pediatric Neurology and Developmental Neuroscience, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
- Texas Children’s Hospital, Houston, Texas, 77030, USA
| | - Dana Marafi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
- Department of Pediatrics, Faculty of Medicine, Kuwait University, P.O. Box 24923, 13110 Safat, Kuwait
| | - James R. Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
- Texas Children’s Hospital, Houston, Texas, 77030, USA
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, 77030, USA
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA
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13
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Dewulf JP, Marie S, Nassogne MC. Disorders of purine biosynthesis metabolism. Mol Genet Metab 2022; 136:190-198. [PMID: 34998670 DOI: 10.1016/j.ymgme.2021.12.016] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 11/15/2021] [Accepted: 12/25/2021] [Indexed: 11/18/2022]
Abstract
Purines are essential molecules that are components of vital biomolecules, such as nucleic acids, coenzymes, signaling molecules, as well as energy transfer molecules. The de novo biosynthesis pathway starts from phosphoribosylpyrophosphate (PRPP) and eventually leads to the synthesis of inosine monophosphate (IMP) by means of 10 sequential steps catalyzed by six different enzymes, three of which are bi-or tri-functional in nature. IMP is then converted into guanosine monophosphate (GMP) or adenosine monophosphate (AMP), which are further phosphorylated into nucleoside di- or tri-phosphates, such as GDP, GTP, ADP and ATP. This review provides an overview of inborn errors of metabolism pertaining to purine synthesis in humans, including either phosphoribosylpyrophosphate synthetase (PRS) overactivity or deficiency, as well as adenylosuccinate lyase (ADSL), 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/IMP cyclohydrolase (ATIC), phosphoribosylaminoimidazole succinocarboxamide synthetase (PAICS), and adenylosuccinate synthetase (ADSS) deficiencies. ITPase deficiency is being described as well. The clinical spectrum of these disorders is broad, including neurological impairment, such as psychomotor retardation, epilepsy, hypotonia, or microcephaly; sensory involvement, such as deafness and visual disturbances; multiple malformations, as well as muscle presentations or consequences of hyperuricemia, such as gouty arthritis or kidney stones. Clinical signs are often nonspecific and, thus, overlooked. It is to be hoped that this is likely to be gradually overcome by using sensitive biochemical investigations and next-generation sequencing technologies.
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Affiliation(s)
- Joseph P Dewulf
- Laboratoire des Maladies Métaboliques Héréditaires/Biochimie Génétique et Centre de Dépistage Néonatal, Cliniques Universitaires Saint-Luc, UCLouvain, B-1200 Brussels, Belgium; Institut des Maladies Rares, Cliniques Universitaires Saint-Luc, UCLouvain, B-1200 Brussels, Belgium; Department of Biochemistry, de Duve Institute, UCLouvain, Brussels, Belgium.
| | - Sandrine Marie
- Laboratoire des Maladies Métaboliques Héréditaires/Biochimie Génétique et Centre de Dépistage Néonatal, Cliniques Universitaires Saint-Luc, UCLouvain, B-1200 Brussels, Belgium; Institut des Maladies Rares, Cliniques Universitaires Saint-Luc, UCLouvain, B-1200 Brussels, Belgium.
| | - Marie-Cécile Nassogne
- Institut des Maladies Rares, Cliniques Universitaires Saint-Luc, UCLouvain, B-1200 Brussels, Belgium; Service de Neurologie Pédiatrique, Cliniques Universitaires Saint-Luc, UCLouvain, B-1200 Brussels, Belgium.
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14
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Sharma Y, Saini AG, Kaur R, Bhatia V, Didwal G, Kumar P, Uppala R. Neurodegeneration and Early Infantile Epilepsy Associated with ITPA Variants: A Case Series and Review of Literature. Neuropediatrics 2022; 53:167-175. [PMID: 35098521 DOI: 10.1055/s-0042-1742322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
BACKGROUND Inosine triphosphate pyrophosphohydrolase (ITPase) deficiency associated with mutations in the ITPA gene is a recently characterized purine pathway defect that presents with early infantile epileptic encephalopathy and lethal course. This disorder is rare, and only 12 cases are reported worldwide. METHODS We report two additional cases of ITPA-associated neurodegeneration and two pathogenic compound heterozygous variants. We also reviewed the previously published cases of ITPA-associated encephalopathy. RESULTS Both cases presented with progressive infantile-onset encephalopathy, severe developmental delay, microcephaly, facial dysmorphism, and epilepsy. Together with the presented two cases, 14 cases were available for analysis. The mean age of presentation was 16.7 ± 12.4 months (range 3-48 m). The most common clinical features at presentation were developmental delay, seizures, microcephaly, and hypotonia, seen in all 14 (100%) patients. The mean age of seizure onset was 4.75 months (range 2-14 m). Cardiomyopathy was noted in 42% of patients where it was explicitly evaluated (n = 5/12). Consanguinity was reported in 77% of the cases. The cardinal neuroradiological features are T2-signal abnormalities and diffusion restriction in the long tracts, especially the posterior limb of the internal capsule and the optic radiation. The majority of the patients died before 4 years of age (85.7%). CONCLUSION ITPA-related encephalopathy presents with infantile-onset neurodegeneration, progressive microcephaly, and epilepsy. Progressive brain atrophy and diffusion restriction in the white matter tracts are important radiological clues.
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Affiliation(s)
- Yashu Sharma
- Department of Pediatrics, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Arushi Gahlot Saini
- Department of Pediatrics, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Rajdeep Kaur
- Department of Pediatrics, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Vikas Bhatia
- Department of Pediatrics, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Gunjan Didwal
- Department of Pediatrics, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Pawan Kumar
- Department of Pediatrics, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Revathi Uppala
- Genetics Division, Sandor Specialty Diagnostic Pvt Ltd, Hyderabad, Telangana, India
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15
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Garg M, Goraya J, Kochar G, Jain V. ITPA-associated developmental and epileptic encephalopathy: characteristic neuroradiological features with novel clinical and biochemical findings. Epileptic Disord 2022; 24:583-588. [PMID: 35770779 DOI: 10.1684/epd.2022.1424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2021] [Accepted: 02/08/2022] [Indexed: 11/17/2022]
Abstract
Developmental and epileptic encephalopathies (DEE) in children have an everexpanding range of rare causes. Mutations in ITPA have been recently described as causative of DEE, but only a small number of patients have been reported so far. We describe two Indian children with novel variants in the ITPA gene. Both patients had characteristic, previously described, neuroradiological findings that helped us suspect this condition even before genetic evaluation. In addition, we present new and rarely reported clinical findings associated with this condition: migrating partial epilepsy, fever-triggered seizures, movement disorder including oculogyria and dystonic tremor. One of the patients also had high cerebrospinal fluid glycine levels. Both patients had drug-responsive epilepsy, in contrast to drug-resistant seizures in previously reported patients. These patients reiterate the utility of awareness of specific neuroradiological findings and subsequent genetic evaluation to help make a precise diagnosis. Our report also extends the clinical spectrum and provides insight into possible biochemical causes for the neuroimaging findings seen in this condition.
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16
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Inosine triphosphate pyrophosphatase from Trypanosoma brucei cleanses cytosolic pools from deaminated nucleotides. Sci Rep 2022; 12:6408. [PMID: 35436992 PMCID: PMC9016069 DOI: 10.1038/s41598-022-10149-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 04/04/2022] [Indexed: 11/09/2022] Open
Abstract
AbstractInosine triphosphate pyrophosphatases (ITPases) are ubiquitous house-cleaning enzymes that specifically recognize deaminated purine nucleotides and catalyze their hydrolytic cleavage. In this work, we have characterized the Trypanosoma brucei ITPase ortholog (TbITPA). Recombinant TbITPA efficiently hydrolyzes (deoxy)ITP and XTP nucleotides into their respective monophosphate form. Immunolocalization analysis performed in bloodstream forms suggests that the primary role of TbITPA is the exclusion of deaminated purines from the cytosolic nucleoside triphosphate pools. Even though ITPA-knockout bloodstream parasites are viable, they are more sensitive to inhibition of IMP dehydrogenase with mycophenolic acid, likely due to an expansion of IMP, the ITP precursor. On the other hand, TbITPA can also hydrolyze the activated form of the antiviral ribavirin although in this case, the absence of ITPase activity in the cell confers protection against this nucleoside analog. This unexpected phenotype is dependant on purine availability and can be explained by the fact that ribavirin monophosphate, the reaction product generated by TbITPA, is a potent inhibitor of trypanosomal IMP dehydrogenase and GMP reductase. In summary, the present study constitutes the first report on a protozoan inosine triphosphate pyrophosphatase involved in the removal of harmful deaminated nucleotides from the cytosolic pool.
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17
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Scala M, Wortmann SB, Kaya N, Stellingwerff MD, Pistorio A, Glamuzina E, van Karnebeek CD, Skrypnyk C, Iwanicka‐Pronicka K, Piekutowska‐Abramczuk D, Ciara E, Tort F, Sheidley B, Poduri A, Jayakar P, Jayakar A, Upadia J, Walano N, Haack TB, Prokisch H, Aldhalaan H, Karimiani EG, Yildiz Y, Ceylan AC, Santiago‐Sim T, Dameron A, Yang H, Toosi MB, Ashrafzadeh F, Akhondian J, Imannezhad S, Mirzadeh HS, Maqbool S, Farid A, Al‐Muhaizea MA, Alshwameen MO, Aldowsari L, Alsagob M, Alyousef A, AlMass R, AlHargan A, Alwadei AH, AlRasheed MM, Colak D, Alqudairy H, Khan S, Lines MA, García Cazorla MÁ, Ribes A, Morava E, Bibi F, Haider S, Ferla MP, Taylor JC, Alsaif HS, Firdous A, Hashem M, Shashkin C, Koneev K, Kaiyrzhanov R, Efthymiou S, Genomics QS, Schmitt‐Mechelke T, Ziegler A, Issa MY, Elbendary HM, Striano P, Alkuraya FS, Zaki MS, Gleeson JG, Barakat TS, Bierau J, van der Knaap MS, Maroofian R, Houlden H. Clinico-radiological features, molecular spectrum, and identification of prognostic factors in developmental and epileptic encephalopathy due to inosine triphosphate pyrophosphatase (ITPase) deficiency. Hum Mutat 2022; 43:403-419. [PMID: 34989426 PMCID: PMC9152572 DOI: 10.1002/humu.24326] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 12/20/2021] [Accepted: 12/29/2021] [Indexed: 12/12/2022]
Abstract
Developmental and epileptic encephalopathy 35 (DEE 35) is a severe neurological condition caused by biallelic variants in ITPA, encoding inosine triphosphate pyrophosphatase, an essential enzyme in purine metabolism. We delineate the genotypic and phenotypic spectrum of DEE 35, analyzing possible predictors for adverse clinical outcomes. We investigated a cohort of 28 new patients and reviewed previously described cases, providing a comprehensive characterization of 40 subjects. Exome sequencing was performed to identify underlying ITPA pathogenic variants. Brain MRI (magnetic resonance imaging) scans were systematically analyzed to delineate the neuroradiological spectrum. Survival curves according to the Kaplan-Meier method and log-rank test were used to investigate outcome predictors in different subgroups of patients. We identified 18 distinct ITPA pathogenic variants, including 14 novel variants, and two deletions. All subjects showed profound developmental delay, microcephaly, and refractory epilepsy followed by neurodevelopmental regression. Brain MRI revision revealed a recurrent pattern of delayed myelination and restricted diffusion of early myelinating structures. Congenital microcephaly and cardiac involvement were statistically significant novel clinical predictors of adverse outcomes. We refined the molecular, clinical, and neuroradiological characterization of ITPase deficiency, and identified new clinical predictors which may have a potentially important impact on diagnosis, counseling, and follow-up of affected individuals.
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Affiliation(s)
- Marcello Scala
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child HealthUniversità Degli Studi di GenovaGenoaItaly
- Pediatric Neurology and Muscular Diseases UnitIRCCS Istituto Giannina GasliniGenoaItaly
- UCL Queen Square Institute of NeurologyUniversity College LondonLondonUK
| | - Saskia B. Wortmann
- Amalia Children's HospitalRadboud University NijmegenNijmegenThe Netherlands
- University Children's HospitalParacelsus Medical UniversitySalzburgAustria
| | - Namik Kaya
- Department of GeneticsKing Faisal Specialist Hospital and Research CentreRiyadhSaudi Arabia
- Department of Translational Genomics, Center for Genomics MedicineKing Faisal Specialist Hospital and Research CentreRiyadhSaudi Arabia
| | - Menno D. Stellingwerff
- Department of Child Neurology, Emma Children's Hospital, Amsterdam Leukodystrophy Center, Amsterdam University Medical CentersVrije Universiteit and Amsterdam NeuroscienceAmsterdamThe Netherlands
| | - Angela Pistorio
- Clinical Epidemiology and Biostatistics UnitIRCCS Istituto Giannina GasliniGenoaItaly
| | - Emma Glamuzina
- Adult and Paediatric National Metabolic ServiceStarship Children's HospitalAucklandNew Zealand
| | - Clara D. van Karnebeek
- Departments of Pediatrics and Clinical GeneticsAcademic Medical CentreAmsterdamThe Netherlands
| | - Cristina Skrypnyk
- Department of Molecular Medicine, Al‐Jawhara Centre for Molecular MedicineArabian Gulf UniversityManamaKingdom of Bahrain
| | - Katarzyna Iwanicka‐Pronicka
- Department of Medical GeneticsThe Children's Memorial Health InstituteWarsawPoland
- Department of Audiology and PhoniatricsThe Children's Memorial Health InstituteWarsawPoland
| | | | - Elżbieta Ciara
- Department of Medical GeneticsThe Children's Memorial Health InstituteWarsawPoland
| | - Frederic Tort
- Secció d'Errors Congènits del Metabolisme‐IBC, Servei de Bioquímica iGenètica MolecularHospital Clínic, IDIBAPS, CIBERERBarcelonaSpain
| | - Beth Sheidley
- Department of NeurologyF.M. Kirby Neurobiology Center, Boston Children's HospitalBostonMassachusettesUSA
- Division of Epilepsy and Clinical Neurophysiology and Epilepsy Genetics ProgramBoston Children's HospitalBostonMassachusettesUSA
| | - Annapurna Poduri
- Department of NeurologyF.M. Kirby Neurobiology Center, Boston Children's HospitalBostonMassachusettesUSA
- Division of Epilepsy and Clinical Neurophysiology and Epilepsy Genetics ProgramBoston Children's HospitalBostonMassachusettesUSA
- Department of NeurologyHarvard Medical SchoolBostonMassachusettesUSA
| | | | | | - Jariya Upadia
- Tulane University School of MedicineNew OrleansLouisianaUSA
| | | | - Tobias B. Haack
- Institute of Medical Genetics and Applied GenomicsUniversity of TübingenTübingenGermany
| | - Holger Prokisch
- Institute of Human GeneticsTechnische Universität MünchenMunichGermany
- Institute of Human GeneticsHelmholtz Zentrum MünchenNeuherbergGermany
| | - Hesham Aldhalaan
- Department of NeurosciencesKing Faisal Specialist Hospital and Research CentreRiyadhSaudi Arabia
| | - Ehsan G. Karimiani
- Department of Medical GeneticsNext Generation Genetic PolyclinicMashhadIran
- Molecular and Clinical Sciences InstituteSt. George's University of London, Cranmer TerraceLondonUK
- Innovative Medical Research CenterIslamic Azad University, Mashhad BranchMashhadIran
| | - Yilmaz Yildiz
- Pediatric Metabolic Diseases ClinicDr. Sami Ulus Training and Research Hospital for Maternity and ChildrenAnkaraTurkey
| | - Ahmet C. Ceylan
- Department of Medical GeneticsAnkara City HospitalAnkaraTurkey
| | | | | | | | - Mehran B. Toosi
- Pediatric Neurology Department, Ghaem HospitalMashhad University of Medical SciencesMashhadIran
| | - Farah Ashrafzadeh
- Department of PediatricsMashhad University of Medical SciencesMashhadIran
| | - Javad Akhondian
- Pediatric Neurology Department, Ghaem HospitalMashhad University of Medical SciencesMashhadIran
| | - Shima Imannezhad
- Department of Pediatric DiseasesMashhad University of Medical SciencesMashhadIran
| | - Hanieh S. Mirzadeh
- Department of Pediatric DiseasesMashhad University of Medical SciencesMashhadIran
| | - Shazia Maqbool
- Development and Behavioral Pediatrics DepartmentInstitute of Child Health and The Children HospitalLahorePakistan
| | - Aisha Farid
- Development and Behavioral Pediatrics DepartmentInstitute of Child Health and The Children HospitalLahorePakistan
| | - Mohamed A. Al‐Muhaizea
- Department of NeurosciencesKing Faisal Specialist Hospital and Research CentreRiyadhSaudi Arabia
| | - Meznah O. Alshwameen
- Department of NeurosciencesKing Faisal Specialist Hospital and Research CentreRiyadhSaudi Arabia
| | - Lama Aldowsari
- Department of GeneticsKing Faisal Specialist Hospital and Research CentreRiyadhSaudi Arabia
| | - Maysoon Alsagob
- Department of GeneticsKing Faisal Specialist Hospital and Research CentreRiyadhSaudi Arabia
| | - Ashwaq Alyousef
- Department of GeneticsKing Faisal Specialist Hospital and Research CentreRiyadhSaudi Arabia
| | - Rawan AlMass
- Department of GeneticsKing Faisal Specialist Hospital and Research CentreRiyadhSaudi Arabia
| | - Aljouhra AlHargan
- Department of GeneticsKing Faisal Specialist Hospital and Research CentreRiyadhSaudi Arabia
| | - Ali H. Alwadei
- Neurosciences DepartmentKing Fahad Medical CityRiyadhSaudi Arabia
| | - Maha M. AlRasheed
- Department of Clinical PharmacyKing Saud UniversityRiyadhSaudi Arabia
| | - Dilek Colak
- Department of Biostatistics, Epidemiology and Scientific ComputingKFSHRCRiyadhKingdom of Saudi Arabia
| | - Hanan Alqudairy
- Department of GeneticsKing Faisal Specialist Hospital and Research CentreRiyadhSaudi Arabia
| | - Sameena Khan
- Department of NeurosciencesKing Faisal Specialist Hospital and Research CentreRiyadhSaudi Arabia
| | - Matthew A. Lines
- Medical Genetics, Department of PediatricsAlberta Children's HospitalCalgaryCanada
| | | | - Antonia Ribes
- Secció d'Errors Congènits del Metabolisme‐IBC, Servei de Bioquímica iGenètica MolecularHospital Clínic, IDIBAPS, CIBERERBarcelonaSpain
| | - Eva Morava
- Department of Clinical Genomics, Laboratory of Medicine and PathologyCenter for Individualized Medicine, Mayo ClinicRochesterMinnesotaUSA
| | - Farah Bibi
- Institute of Biochemistry and BiotechnologyPir Mehar Ali Shah Arid Agriculture UniversityRawalpindiPakistan
| | - Shahzad Haider
- Izzat Ali Shah HospitalLalarukh Wah CanttRawalpindiPakistan
| | - Matteo P. Ferla
- NIHR Oxford BRC Genomic Medicine, Wellcome Centre for Human GeneticsUniversity of OxfordOxfordUK
| | - Jenny C. Taylor
- NIHR Oxford BRC Genomic Medicine, Wellcome Centre for Human GeneticsUniversity of OxfordOxfordUK
| | - Hessa S. Alsaif
- Department of Translational Genomics, Center for Genomics MedicineKing Faisal Specialist Hospital and Research CentreRiyadhSaudi Arabia
| | - Abdulwahab Firdous
- Department of Translational Genomics, Center for Genomics MedicineKing Faisal Specialist Hospital and Research CentreRiyadhSaudi Arabia
| | - Mais Hashem
- Department of Translational Genomics, Center for Genomics MedicineKing Faisal Specialist Hospital and Research CentreRiyadhSaudi Arabia
| | - Chingiz Shashkin
- International University of Postgraduate EducationAlmatyKazakhstan
| | - Kairgali Koneev
- Department of Neurology and NeurosurgeryAsfendiyarov Kazakh National Medical UniversityAlmatyKazakhstan
| | - Rauan Kaiyrzhanov
- UCL Queen Square Institute of NeurologyUniversity College LondonLondonUK
| | | | | | | | - Andreas Ziegler
- Zentrum für Kinder und Jugendmedizin Heidelberg, Sektion Neuropädiatrie und StoffwechselmedizinUniversitätsklinikum HeidelbergHeidelbergGermany
| | - Mahmoud Y. Issa
- Clinical Genetics Department, Human Genetics and Genome Research DivisionNational Research CentreCairoEgypt
| | - Hasnaa M. Elbendary
- Clinical Genetics Department, Human Genetics and Genome Research DivisionNational Research CentreCairoEgypt
| | - Pasquale Striano
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child HealthUniversità Degli Studi di GenovaGenoaItaly
- Pediatric Neurology and Muscular Diseases UnitIRCCS Istituto Giannina GasliniGenoaItaly
| | - Fowzan S. Alkuraya
- Department of Translational Genomics, Center for Genomics MedicineKing Faisal Specialist Hospital and Research CentreRiyadhSaudi Arabia
- Department of Anatomy and Cell BiologyAlfaisal UniversityRiyadhSaudi Arabia
| | - Maha S. Zaki
- Clinical Genetics Department, Human Genetics and Genome Research DivisionNational Research CentreCairoEgypt
| | - Joseph G. Gleeson
- Department of Neuroscience, Rady Children's Institute for Genomic Medicine, Howard Hughes Medical InstituteUniversity of CaliforniaSan DiegoCaliforniaUSA
| | - Tahsin Stefan Barakat
- Department of Clinical Genetics, Erasmus MCUniversity Medical CenterRotterdamThe Netherlands
| | - Jorgen Bierau
- Laboratory of Biochemical Genetics, Department of Clinical GeneticsMaastricht University HospitalMaastrichtThe Netherlands
| | - Marjo S. van der Knaap
- Department of Child Neurology, Emma Children's Hospital, Amsterdam Leukodystrophy Center, Amsterdam University Medical CentersVrije Universiteit and Amsterdam NeuroscienceAmsterdamThe Netherlands
- Department of Functional Genomics, Center for Neurogenomics and Cognitive ResearchVU UniversityAmsterdamThe Netherlands
| | - Reza Maroofian
- UCL Queen Square Institute of NeurologyUniversity College LondonLondonUK
| | - Henry Houlden
- UCL Queen Square Institute of NeurologyUniversity College LondonLondonUK
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18
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Zamzami MA. Inosine Triphosphate Pyrophosphatase (ITPase): Functions, Mutations, Polymorphisms and Its Impact on Cancer Therapies. Cells 2022; 11:384. [PMID: 35159194 PMCID: PMC8833965 DOI: 10.3390/cells11030384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 01/18/2022] [Accepted: 01/19/2022] [Indexed: 11/16/2022] Open
Abstract
Inosine triphosphate pyrophosphatase (ITPase) is an enzyme encoded by the ITPA gene and functions to prevent the incorporation of noncanonical purine nucleotides into DNA and RNA. Specifically, the ITPase catalyzed the hydrolysis of (deoxy) nucleoside triphosphates ((d) NTPs) into the corresponding nucleoside monophosphate with the concomitant release of pyrophosphate. Recently, thiopurine drug metabolites such as azathioprine have been included in the lists of ITPase substrates. Interestingly, inosine or xanthosine triphosphate (ITP/XTP) and their deoxy analogs, deoxy inosine or xanthosine triphosphate (dITP/dXTP), are products of important biological reactions such as deamination that take place within the cellular compartments. However, the incorporation of ITP/XTP, dITP/dXTP, or the genetic deficiency or polymorphism of the ITPA gene have been implicated in many human diseases, including infantile epileptic encephalopathy, early onset of tuberculosis, and the responsiveness of patients to cancer therapy. This review provides an up-to-date report on the ITPase enzyme, including information regarding its discovery, analysis, and cellular localization, its implication in human diseases including cancer, and its therapeutic potential, amongst others.
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Affiliation(s)
- Mazin A. Zamzami
- Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia;
- Centre of Artificial Intelligence in Precision Medicines, King Abdulaziz University, Jeddah 21589, Saudi Arabia
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19
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Srinivasan S, Torres AG, Ribas de Pouplana L. Inosine in Biology and Disease. Genes (Basel) 2021; 12:600. [PMID: 33921764 PMCID: PMC8072771 DOI: 10.3390/genes12040600] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 04/13/2021] [Accepted: 04/15/2021] [Indexed: 02/06/2023] Open
Abstract
The nucleoside inosine plays an important role in purine biosynthesis, gene translation, and modulation of the fate of RNAs. The editing of adenosine to inosine is a widespread post-transcriptional modification in transfer RNAs (tRNAs) and messenger RNAs (mRNAs). At the wobble position of tRNA anticodons, inosine profoundly modifies codon recognition, while in mRNA, inosines can modify the sequence of the translated polypeptide or modulate the stability, localization, and splicing of transcripts. Inosine is also found in non-coding and exogenous RNAs, where it plays key structural and functional roles. In addition, molecular inosine is an important secondary metabolite in purine metabolism that also acts as a molecular messenger in cell signaling pathways. Here, we review the functional roles of inosine in biology and their connections to human health.
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Affiliation(s)
- Sundaramoorthy Srinivasan
- Institute for Research in Biomedicine, Barcelona Institute of Science and Technology, 08028 Barcelona, Catalonia, Spain; (S.S.); (A.G.T.)
| | - Adrian Gabriel Torres
- Institute for Research in Biomedicine, Barcelona Institute of Science and Technology, 08028 Barcelona, Catalonia, Spain; (S.S.); (A.G.T.)
| | - Lluís Ribas de Pouplana
- Institute for Research in Biomedicine, Barcelona Institute of Science and Technology, 08028 Barcelona, Catalonia, Spain; (S.S.); (A.G.T.)
- Catalan Institution for Research and Advanced Studies, 08010 Barcelona, Catalonia, Spain
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20
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Muthusamy K, Boyer S, Patterson M, Bierau J, Wortmann S, Morava E. Teaching NeuroImages: Neuroimaging Findings in Inosine Triphosphate Pyrophosphohydrolase Deficiency. Neurology 2021; 97:e109-e110. [PMID: 33593863 DOI: 10.1212/wnl.0000000000011719] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Karthik Muthusamy
- From the Departments of Clinical Genomics (K.M., S.B., E.M.), Neurology, Pediatrics, Clinical Genomics (M.P.), and Laboratory Medicine and Pathology (E.M.), Mayo Clinic, Rochester, MN; Department of Laboratory Medicine (J.B.), Maastricht University, the Netherlands; University Children's Hospital (S.W.), Paracelsus Medical University (PMU), Salzburg, Austria; and Amalia Children's Hospital (S.W.), Radboud UMC, Nijmegen, the Netherlands
| | - Suzanne Boyer
- From the Departments of Clinical Genomics (K.M., S.B., E.M.), Neurology, Pediatrics, Clinical Genomics (M.P.), and Laboratory Medicine and Pathology (E.M.), Mayo Clinic, Rochester, MN; Department of Laboratory Medicine (J.B.), Maastricht University, the Netherlands; University Children's Hospital (S.W.), Paracelsus Medical University (PMU), Salzburg, Austria; and Amalia Children's Hospital (S.W.), Radboud UMC, Nijmegen, the Netherlands
| | - Marc Patterson
- From the Departments of Clinical Genomics (K.M., S.B., E.M.), Neurology, Pediatrics, Clinical Genomics (M.P.), and Laboratory Medicine and Pathology (E.M.), Mayo Clinic, Rochester, MN; Department of Laboratory Medicine (J.B.), Maastricht University, the Netherlands; University Children's Hospital (S.W.), Paracelsus Medical University (PMU), Salzburg, Austria; and Amalia Children's Hospital (S.W.), Radboud UMC, Nijmegen, the Netherlands
| | - Jorgen Bierau
- From the Departments of Clinical Genomics (K.M., S.B., E.M.), Neurology, Pediatrics, Clinical Genomics (M.P.), and Laboratory Medicine and Pathology (E.M.), Mayo Clinic, Rochester, MN; Department of Laboratory Medicine (J.B.), Maastricht University, the Netherlands; University Children's Hospital (S.W.), Paracelsus Medical University (PMU), Salzburg, Austria; and Amalia Children's Hospital (S.W.), Radboud UMC, Nijmegen, the Netherlands
| | - Saskia Wortmann
- From the Departments of Clinical Genomics (K.M., S.B., E.M.), Neurology, Pediatrics, Clinical Genomics (M.P.), and Laboratory Medicine and Pathology (E.M.), Mayo Clinic, Rochester, MN; Department of Laboratory Medicine (J.B.), Maastricht University, the Netherlands; University Children's Hospital (S.W.), Paracelsus Medical University (PMU), Salzburg, Austria; and Amalia Children's Hospital (S.W.), Radboud UMC, Nijmegen, the Netherlands
| | - Eva Morava
- From the Departments of Clinical Genomics (K.M., S.B., E.M.), Neurology, Pediatrics, Clinical Genomics (M.P.), and Laboratory Medicine and Pathology (E.M.), Mayo Clinic, Rochester, MN; Department of Laboratory Medicine (J.B.), Maastricht University, the Netherlands; University Children's Hospital (S.W.), Paracelsus Medical University (PMU), Salzburg, Austria; and Amalia Children's Hospital (S.W.), Radboud UMC, Nijmegen, the Netherlands.
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21
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Koga Y, Tsuchimoto D, Hayashi Y, Abolhassani N, Yoneshima Y, Sakumi K, Nakanishi H, Toyokuni S, Nakabeppu Y. Neural stem cell-specific ITPA deficiency causes neural depolarization and epilepsy. JCI Insight 2020; 5:140229. [PMID: 33208550 PMCID: PMC7710303 DOI: 10.1172/jci.insight.140229] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 10/15/2020] [Indexed: 11/17/2022] Open
Abstract
Inosine triphosphate pyrophosphatase (ITPA) hydrolyzes inosine triphosphate (ITP) and other deaminated purine nucleotides to the corresponding nucleoside monophosphates. In humans, ITPA deficiency causes severe encephalopathy with epileptic seizure, microcephaly, and developmental retardation. In this study, we established neural stem cell-specific Itpa-conditional KO mice (Itpa-cKO mice) to clarify the effects of ITPA deficiency on the neural system. The Itpa-cKO mice showed growth retardation and died within 3 weeks of birth. We did not observe any microcephaly in the Itpa-cKO mice, although the female Itpa-cKO mice did show adrenal hypoplasia. The Itpa-cKO mice showed limb-clasping upon tail suspension and spontaneous and/or audiogenic seizure. Whole-cell patch-clamp recordings from entorhinal cortex neurons in brain slices revealed a depolarized resting membrane potential, increased firing, and frequent spontaneous miniature excitatory postsynaptic current and miniature inhibitory postsynaptic current in the Itpa-cKO mice compared with ITPA-proficient controls. Accumulated ITP or its metabolites, such as cyclic inosine monophosphates, or RNA containing inosines may cause membrane depolarization and hyperexcitability in neurons and induce the phenotype of ITPA-deficient mice, including seizure.
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Affiliation(s)
- Yuichiro Koga
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, and
| | - Daisuke Tsuchimoto
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, and
| | - Yoshinori Hayashi
- Department of Aging Science and Pharmacology, Faculty of Dental Sciences, Kyushu University, Fukuoka, Japan
- Department of Physiology, Nihon University School of Dentistry, Tokyo, Japan
| | - Nona Abolhassani
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, and
| | - Yasuto Yoneshima
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, and
| | - Kunihiko Sakumi
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, and
| | - Hiroshi Nakanishi
- Department of Pharmacology, Faculty of Pharmacy, Yasuda Women’s University, Hiroshima, Japan
| | - Shinya Toyokuni
- Department of Pathology and Biological Responses, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yusaku Nakabeppu
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, and
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22
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Sakamoto M, Kouhei D, Haniffa M, Silva S, Troncoso M, Santander P, Schonstedt V, Stecher X, Okamoto N, Hamanaka K, Mizuguchi T, Mitsuhashi S, Miyake N, Matsumoto N. A novel ITPA variant causes epileptic encephalopathy with multiple-organ dysfunction. J Hum Genet 2020; 65:751-757. [PMID: 32405030 DOI: 10.1038/s10038-020-0765-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 03/18/2020] [Accepted: 04/13/2020] [Indexed: 11/09/2022]
Abstract
Inborn errors of metabolism can cause epileptic encephalopathies. Biallelic loss-of-function variants in the ITPA gene, encoding inosine triphosphate pyrophosphatase (ITPase), have been reported in epileptic encephalopathies with lack of myelination of the posterior limb of the internal capsule, brainstem tracts, and tracts to the primary visual and motor cortices (MIM:616647). ITPase plays an important role in purine metabolism. In this study, we identified two novel homozygous ITPA variants, c.264-1 G > A and c.489-1 G > A, in two unrelated consanguineous families. The probands had epilepsy, microcephaly with characteristic magnetic resonance imaging findings (T2 hyperintensity signals in the pyramidal tracts of the internal capsule, delayed myelination, and thin corpus callosum), hypotonia, and developmental delay; both died in early infancy. Our report expands the knowledge of clinical consequences of biallelic ITPA variants.
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Affiliation(s)
- Masamune Sakamoto
- Department of Human Genetics, Graduate School of Medicine, Yokohama City University, Yokohama, Japan.,Department of Pediatrics, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
| | - Den Kouhei
- Department of Human Genetics, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
| | - Muzhirah Haniffa
- Department of Genetics, Hospital Kuala Lumpur, Jalan Pahang, Malaysia
| | - Sebastián Silva
- Child Neurology Service, Hospital de Puerto Montt, Puerto Montt, Chile
| | - Mónica Troncoso
- Child Neurology Service, Hospital San Borja Arriarán, Universidad de Chile, Santiago, Chile
| | - Paola Santander
- Child Neurology Service, Hospital San Borja Arriarán, Universidad de Chile, Santiago, Chile
| | | | - Ximena Stecher
- Department of Radiology, Clínica Alemana de Santiago, Santiago, Chile.,Department of Radiology, Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, Santiago, Chile
| | | | - Kohei Hamanaka
- Department of Human Genetics, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
| | - Takeshi Mizuguchi
- Department of Human Genetics, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
| | - Satomi Mitsuhashi
- Department of Human Genetics, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
| | - Noriko Miyake
- Department of Human Genetics, Graduate School of Medicine, Yokohama City University, Yokohama, Japan.
| | - Naomichi Matsumoto
- Department of Human Genetics, Graduate School of Medicine, Yokohama City University, Yokohama, Japan.
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23
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Burgess R, Wang S, McTague A, Boysen KE, Yang X, Zeng Q, Myers KA, Rochtus A, Trivisano M, Gill D, Sadleir LG, Specchio N, Guerrini R, Marini C, Zhang YH, Mefford HC, Kurian MA, Poduri AH, Scheffer IE. The Genetic Landscape of Epilepsy of Infancy with Migrating Focal Seizures. Ann Neurol 2020; 86:821-831. [PMID: 31618474 DOI: 10.1002/ana.25619] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 08/30/2019] [Accepted: 10/06/2019] [Indexed: 12/29/2022]
Abstract
OBJECTIVE Epilepsy of infancy with migrating focal seizures (EIMFS) is one of the most severe developmental and epileptic encephalopathies. We delineate the genetic causes and genotype-phenotype correlations of a large EIMFS cohort. METHODS Phenotypic and molecular data were analyzed on patients recruited through an international collaborative study. RESULTS We ascertained 135 patients from 128 unrelated families. Ninety-three of 135 (69%) had causative variants (42/55 previously reported) across 23 genes, including 9 novel EIMFS genes: de novo dominant GABRA1, GABRB1, ATP1A3; X-linked CDKL5, PIGA; and recessive ITPA, AIMP1, KARS, WWOX. The most frequently implicated genes were KCNT1 (36/135, 27%) and SCN2A (10/135, 7%). Mosaicism occurred in 2 probands (SCN2A, GABRB3) and 3 unaffected mothers (KCNT1). Median age at seizure onset was 4 weeks, with earlier onset in the SCN2A, KCNQ2, and BRAT1 groups. Epileptic spasms occurred in 22% patients. A total of 127 patients had severe to profound developmental impairment. All but 7 patients had ongoing seizures. Additional features included microcephaly, movement disorders, spasticity, and scoliosis. Mortality occurred in 33% at median age 2 years 7 months. INTERPRETATION We identified a genetic cause in 69% of patients with EIMFS. We highlight the genetic heterogeneity of EIMFS with 9 newly implicated genes, bringing the total number to 33. Mosaicism was observed in probands and parents, carrying critical implications for recurrence risk. EIMFS pathophysiology involves diverse molecular processes from gene and protein regulation to ion channel function and solute trafficking. ANN NEUROL 2019;86:821-831.
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Affiliation(s)
- Rosemary Burgess
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Melbourne, Victoria, Australia
| | - Shuyu Wang
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Melbourne, Victoria, Australia.,School of Clinical Sciences, Monash University, Monash Health, Melbourne, Victoria, Australia
| | - Amy McTague
- Molecular Neurosciences, Developmental Neurosciences, University College London Great Ormond Street Institute of Child Health, London, United Kingdom
| | - Katja E Boysen
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Melbourne, Victoria, Australia
| | - Xiaoling Yang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Qi Zeng
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Kenneth A Myers
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Melbourne, Victoria, Australia.,Research Institute of the McGill University Health Centre; Montreal, Quebec, Canada.,Division of Neurology, Department of Pediatrics, Montreal Children's Hospital, McGill University Health Centre, Montreal, Quebec, Canada
| | - Anne Rochtus
- Epilepsy Genetics Program, Boston Children's Hospital, Boston, MA
| | - Marina Trivisano
- Rare and Complex Epilepsies Unit, Department of Neuroscience, Bambino Gesù Children's Hospital, Scientific Institute for Research and Health Care, Rome, Italy
| | - Deepak Gill
- T. Y. Nelson Department of Neurology and Neurosurgery, Children's Hospital at Westmead, Sydney, New South Wales, Australia
| | | | - Lynette G Sadleir
- Department of Paediatrics and Child Health, University of Otago Wellington, Wellington, New Zealand
| | - Nicola Specchio
- Rare and Complex Epilepsies Unit, Department of Neuroscience, Bambino Gesù Children's Hospital, Scientific Institute for Research and Health Care, Rome, Italy
| | - Renzo Guerrini
- Pediatric Neurology, Neurogenetics, and Neurobiology Unit and Laboratories, Children's Hospital A. Meyer-University of Florence, Florence, Italy
| | - Carla Marini
- Pediatric Neurology, Neurogenetics, and Neurobiology Unit and Laboratories, Children's Hospital A. Meyer-University of Florence, Florence, Italy
| | - Yue-Hua Zhang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Heather C Mefford
- Department of Pediatrics, Division of Genetic Medicine, University of Washington, Seattle, WA
| | - Manju A Kurian
- Molecular Neurosciences, Developmental Neurosciences, University College London Great Ormond Street Institute of Child Health, London, United Kingdom.,Department of Neurology, Great Ormond Street Hospital for Children National Health Service Foundation Trust, London, United Kingdom
| | - Annapurna H Poduri
- Epilepsy Genetics Program, Boston Children's Hospital, Boston, MA.,Department of Neurology, Harvard Medical School, Boston, MA
| | - Ingrid E Scheffer
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Melbourne, Victoria, Australia.,Florey Institute for Neuroscience and Mental Health, Melbourne, Victoria, Australia.,Department of Neurology, Royal Children's Hospital, Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia.,Murdoch Children's Research Institute, Melbourne, Victoria, Australia
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24
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Houndonougbo Y, Pugh B, VanWormer K, April C, Burgis N. Structural dynamics of inosine triphosphate pyrophosphatase (ITPA) protein and two clinically relevant mutants: molecular dynamics simulations. J Biomol Struct Dyn 2020; 39:1236-1247. [PMID: 32129147 DOI: 10.1080/07391102.2020.1727363] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The inosine triphosphate pyrophosphatase (ITPA) protein is responsible for removing noncanonical purine nucleoside triphosphates from intracellular nucleotide pools. Absence of ITPA results in genomic instability and increased levels of inosine in DNA and RNA. The proline to threonine substitution at position 32 (P32T) affects roughly 15% of the global population and can modulate treatment outcomes for cancer, lupus, and hepatitis C patients. The substitution of arginine with cysteine at position 178 (R178C) is extremely uncommon and has only been reported in a small cohort of early infantile encephalopathy patients suggesting that a functional ITPA protein is required for life in humans. Here we present molecular dynamic simulations that describe the structure and dynamics of the wild-type ITPA homodimer and two of its clinically relevant mutants, P32T and R178C. The simulation results indicate that both the P32T and R178C mutations alter the structure and dynamic properties of the protein and provide a possible explanation of the experimentally observed effect of the mutations on ITPA activity. Specifically, the mutations increased the overall flexibility of the protein and changed the dominant collective motions of the top lobe as well as the helix 2 of the lower lobe. Moreover, we have identified key active-site residues that are classified as essential or intermediate for inosine triphosphate (ITP) hydrolyzing activity based on their hydrogen bond occupancy. Here we also present biochemical data indicating that the R178C mutant has very low ITP hydrolyzing activity.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Yao Houndonougbo
- Department of Chemistry and Biochemistry, Eastern Washington University, Cheney, WA, USA
| | - Bethany Pugh
- Department of Chemistry and Biochemistry, Eastern Washington University, Cheney, WA, USA
| | - Kandise VanWormer
- Department of Chemistry and Biochemistry, Eastern Washington University, Cheney, WA, USA
| | - Caitlin April
- Department of Chemistry and Biochemistry, Eastern Washington University, Cheney, WA, USA
| | - Nicholas Burgis
- Department of Chemistry and Biochemistry, Eastern Washington University, Cheney, WA, USA
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25
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Rochtus A, Olson HE, Smith L, Keith LG, El Achkar C, Taylor A, Mahida S, Park M, Kelly M, Shain C, Rockowitz S, Sheidley BR, Poduri A. Genetic diagnoses in epilepsy: The impact of dynamic exome analysis in a pediatric cohort. Epilepsia 2020; 61:249-258. [PMID: 31957018 PMCID: PMC7404709 DOI: 10.1111/epi.16427] [Citation(s) in RCA: 76] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 12/18/2019] [Accepted: 12/20/2019] [Indexed: 01/02/2023]
Abstract
OBJECTIVE We evaluated the yield of systematic analysis and/or reanalysis of whole exome sequencing (WES) data from a cohort of well-phenotyped pediatric patients with epilepsy and suspected but previously undetermined genetic etiology. METHODS We identified and phenotyped 125 participants with pediatric epilepsy. Etiology was unexplained at the time of enrollment despite clinical testing, which included chromosomal microarray (57 patients), epilepsy gene panel (n = 48), both (n = 28), or WES (n = 8). Clinical epilepsy diagnoses included developmental and epileptic encephalopathy (DEE), febrile infection-related epilepsy syndrome, Rasmussen encephalitis, and other focal and generalized epilepsies. We analyzed WES data and compared the yield in participants with and without prior clinical genetic testing. RESULTS Overall, we identified pathogenic or likely pathogenic variants in 40% (50/125) of our study participants. Nine patients with DEE had genetic variants in recently published genes that had not been recognized as epilepsy-related at the time of clinical testing (FGF12, GABBR1, GABBR2, ITPA, KAT6A, PTPN23, RHOBTB2, SATB2), and eight patients had genetic variants in candidate epilepsy genes (CAMTA1, FAT3, GABRA6, HUWE1, PTCHD1). Ninety participants had concomitant or subsequent clinical genetic testing, which was ultimately explanatory for 26% (23/90). Of the 67 participants whose molecular diagnoses were "unsolved" through clinical genetic testing, we identified pathogenic or likely pathogenic variants in 17 (25%). SIGNIFICANCE Our data argue for early consideration of WES with iterative reanalysis for patients with epilepsy, particularly those with DEE or epilepsy with intellectual disability. Rigorous analysis of WES data of well-phenotyped patients with epilepsy leads to a broader understanding of gene-specific phenotypic spectra as well as candidate disease gene identification. We illustrate the dynamic nature of genetic diagnosis over time, with analysis and in some cases reanalysis of exome data leading to the identification of disease-associated variants among participants with previously nondiagnostic results from a variety of clinical testing strategies.
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Affiliation(s)
- Anne Rochtus
- Epilepsy Genetics Program, Department of Neurology, Boston Children’s Hospital, Boston, MA, USA
- Department of Pediatrics, University of Leuven, Leuven, Belgium
| | - Heather E. Olson
- Epilepsy Genetics Program, Department of Neurology, Boston Children’s Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Lacey Smith
- Epilepsy Genetics Program, Department of Neurology, Boston Children’s Hospital, Boston, MA, USA
| | - Louisa G. Keith
- Epilepsy Genetics Program, Department of Neurology, Boston Children’s Hospital, Boston, MA, USA
| | - Christelle El Achkar
- Epilepsy Genetics Program, Department of Neurology, Boston Children’s Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Alan Taylor
- Department of Genomics, Al Jalila Children’s Specialty Hospital, Dubai, UAE
| | - Sonal Mahida
- Epilepsy Genetics Program, Department of Neurology, Boston Children’s Hospital, Boston, MA, USA
| | - Meredith Park
- Epilepsy Genetics Program, Department of Neurology, Boston Children’s Hospital, Boston, MA, USA
| | - McKenna Kelly
- Epilepsy Genetics Program, Department of Neurology, Boston Children’s Hospital, Boston, MA, USA
| | - Catherine Shain
- Epilepsy Genetics Program, Department of Neurology, Boston Children’s Hospital, Boston, MA, USA
| | - Shira Rockowitz
- Information Services Department, Boston Children’s Hospital, Boston, MA, USA
| | - Beth Rosen Sheidley
- Epilepsy Genetics Program, Department of Neurology, Boston Children’s Hospital, Boston, MA, USA
| | - Annapurna Poduri
- Epilepsy Genetics Program, Department of Neurology, Boston Children’s Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
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26
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Handley MT, Reddy K, Wills J, Rosser E, Kamath A, Halachev M, Falkous G, Williams D, Cox P, Meynert A, Raymond ES, Morrison H, Brown S, Allan E, Aligianis I, Jackson AP, Ramsahoye BH, von Kriegsheim A, Taylor RW, Finch AJ, FitzPatrick DR. ITPase deficiency causes a Martsolf-like syndrome with a lethal infantile dilated cardiomyopathy. PLoS Genet 2019; 15:e1007605. [PMID: 30856165 PMCID: PMC6428344 DOI: 10.1371/journal.pgen.1007605] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 03/21/2019] [Accepted: 12/27/2018] [Indexed: 12/30/2022] Open
Abstract
Typical Martsolf syndrome is characterized by congenital cataracts, postnatal microcephaly, developmental delay, hypotonia, short stature and biallelic hypomorphic mutations in either RAB3GAP1 or RAB3GAP2. Genetic analysis of 85 unrelated "mutation negative" probands with Martsolf or Martsolf-like syndromes identified two individuals with different homozygous null mutations in ITPA, the gene encoding inosine triphosphate pyrophosphatase (ITPase). Both probands were from multiplex families with a consistent, lethal and highly distinctive disorder; a Martsolf-like syndrome with infantile-onset dilated cardiomyopathy. Severe ITPase-deficiency has been previously reported with infantile epileptic encephalopathy (MIM 616647). ITPase acts to prevent incorporation of inosine bases (rI/dI) into RNA and DNA. In Itpa-null cells dI was undetectable in genomic DNA. dI could be identified at a low level in mtDNA without detectable mitochondrial genome instability, mtDNA depletion or biochemical dysfunction of the mitochondria. rI accumulation was detectable in proband-derived lymphoblastoid RNA. In Itpa-null mouse embryos rI was detectable in the brain and kidney with the highest level seen in the embryonic heart (rI at 1 in 385 bases). Transcriptome and proteome analysis in mutant cells revealed no major differences with controls. The rate of transcription and the total amount of cellular RNA also appeared normal. rI accumulation in RNA-and by implication rI production-correlates with the severity of organ dysfunction in ITPase deficiency but the basis of the cellulopathy remains cryptic. While we cannot exclude cumulative minor effects, there are no major anomalies in the production, processing, stability and/or translation of mRNA.
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Affiliation(s)
- Mark T. Handley
- MRC Human Genetics Unit, Institute of Genomic and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
- Section of Genetics, Leeds Institute of Biomedical and Clinical Sciences, University of Leeds, Leeds, United Kigndom
| | - Kaalak Reddy
- MRC Human Genetics Unit, Institute of Genomic and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
- University of Florida College of Medicine, Center for NeuroGenetics, Gainesville, United States of America
| | - Jimi Wills
- Edinburgh Cancer Research Centre, MRC Institute of Genomic and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Elisabeth Rosser
- Department of Clinical Genetics, Great Ormond St Hospital, London, United Kingdom
| | - Archith Kamath
- Medical School, University of Oxford, John Radcliffe Hospital Oxford United Kingdom
| | - Mihail Halachev
- MRC Human Genetics Unit, Institute of Genomic and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Gavin Falkous
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Denise Williams
- Department of Clinical Genetics, Birmingham Women's and Children's NHSFT, Birmingham, United Kingdom
| | - Phillip Cox
- Department of Histopathology, Birmingham Women's and Children's NHSFT, Birmingham United Kingdom
| | - Alison Meynert
- MRC Human Genetics Unit, Institute of Genomic and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Eleanor S. Raymond
- MRC Human Genetics Unit, Institute of Genomic and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Harris Morrison
- MRC Human Genetics Unit, Institute of Genomic and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Stephen Brown
- MRC Human Genetics Unit, Institute of Genomic and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Emma Allan
- CBS-IGMM Transgenic Unit, University of Edinburgh, Edinburgh, United Kingdom
| | - Irene Aligianis
- MRC Human Genetics Unit, Institute of Genomic and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Andrew P. Jackson
- MRC Human Genetics Unit, Institute of Genomic and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Bernard H. Ramsahoye
- Centre for Genetic and Experimental Medicine, Institute of Genomic and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Alex von Kriegsheim
- Edinburgh Cancer Research Centre, MRC Institute of Genomic and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Robert W. Taylor
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Andrew J. Finch
- Edinburgh Cancer Research Centre, MRC Institute of Genomic and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - David R. FitzPatrick
- MRC Human Genetics Unit, Institute of Genomic and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
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27
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Kaur P, Neethukrishna K, Kumble A, Girisha KM, Shukla A. Identification of a novel homozygous variant confirms ITPA as a developmental and epileptic encephalopathy gene. Am J Med Genet A 2019; 179:857-861. [PMID: 30816001 DOI: 10.1002/ajmg.a.61103] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 01/24/2019] [Accepted: 01/26/2019] [Indexed: 11/07/2022]
Abstract
ITPA related epileptic encephalopathy (epileptic encephalopathy, early infantile, 35) is a rare inborn error of metabolism. All reported individuals with this condition, including the present case manifest global developmental delay, seizures, progressive postnatal microcephaly, hypotonia, thin corpus callosum, cerebral atrophy, delayed myelination and white matter changes in posterior limb of internal capsule. Cataract and dilated cardiomyopathy are other characteristic findings. Currently, a single publication describes this condition in four families. Three truncating and two missense variants in ITPA have been identified in these families. We hereby report another family with ITPA related disorder and review the genotype and phenotype of the reported subjects.
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Affiliation(s)
- Parneet Kaur
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Kausthubham Neethukrishna
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Ali Kumble
- Department of Paediatrics, Indiana Hospital and Heart Institute, Mangalore, India
| | - Katta M Girisha
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Anju Shukla
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
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28
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Calhoun JD, Carvill GL. Unravelling the genetic architecture of autosomal recessive epilepsy in the genomic era. J Neurogenet 2018; 32:295-312. [PMID: 30247086 DOI: 10.1080/01677063.2018.1513509] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The technological advancement of next-generation sequencing has greatly accelerated the pace of variant discovery in epilepsy. Despite an initial focus on autosomal dominant epilepsy due to the tractable nature of variant discovery with trios under a de novo model, more and more variants are being reported in families with epilepsies consistent with autosomal recessive (AR) inheritance. In this review, we touch on the classical AR epilepsy variants such as the inborn errors of metabolism and malformations of cortical development. However, we also highlight recently reported genes that are being identified by next-generation sequencing approaches and online 'matchmaking' platforms. Syndromes mainly characterized by seizures and complex neurodevelopmental disorders comorbid with epilepsy are discussed as an example of the wide phenotypic spectrum associated with the AR epilepsies. We conclude with a foray into the future, from the application of whole-genome sequencing to identify elusive epilepsy variants, to the promise of precision medicine initiatives to provide novel targeted therapeutics specific to the individual based on their clinical genetic testing.
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Affiliation(s)
- Jeffrey D Calhoun
- a Department of Neurology , Northwestern University Feinberg School of Medicine , Chicago , IL , USA
| | - Gemma L Carvill
- a Department of Neurology , Northwestern University Feinberg School of Medicine , Chicago , IL , USA
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29
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Orsini A, Bonuccelli A, Striano P, Azzara A, Costagliola G, Consolini R, Peroni DG, Valetto A, Bertini V. Generalized epilepsy and mild intellectual disability associated with 13q34 deletion: A potential role for SOX1 and ARHGEF7. Seizure 2018; 59:38-40. [PMID: 29734022 DOI: 10.1016/j.seizure.2018.04.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 04/19/2018] [Accepted: 04/21/2018] [Indexed: 10/17/2022] Open
Abstract
Terminal deletions of long arm of chromosome 13 are rare and poorly characterized by cytogenetic studies, making for difficult genotype-phenotype correlations. We report two siblings presenting generalized epilepsy, intellectual disability, and genitourinary tract defects. Array CGH detected a 1.3 Mb deletion at 13q34; it contains two protein-coding genes, SOX1 and ARHGEF7, whose haploinsufficiency can contribute to the epileptic phenotype.
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Affiliation(s)
- A Orsini
- U.O Pediatria, Azienda Ospedaliera Universitaria Pisana, Università di Pisa, Italy.
| | - A Bonuccelli
- U.O Pediatria, Azienda Ospedaliera Universitaria Pisana, Università di Pisa, Italy
| | - P Striano
- Neurologia Pediatrica e Malattie Muscolari, Dipartimento di Neuroscienze, Riabilitazione, Oftalmologia, Genetica e Scienze Materno-Infantili, Istituto 'G. Gaslini', Università di Genova, Italy
| | - A Azzara
- SOD Citogenetica, Azienda Ospedaliera Universitaria Pisana, Italy
| | - G Costagliola
- U.O Pediatria, Azienda Ospedaliera Universitaria Pisana, Università di Pisa, Italy
| | - R Consolini
- U.O Pediatria, Azienda Ospedaliera Universitaria Pisana, Università di Pisa, Italy
| | - D G Peroni
- U.O Pediatria, Azienda Ospedaliera Universitaria Pisana, Università di Pisa, Italy
| | - A Valetto
- SOD Citogenetica, Azienda Ospedaliera Universitaria Pisana, Italy
| | - V Bertini
- SOD Citogenetica, Azienda Ospedaliera Universitaria Pisana, Italy
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30
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Charbgoo F, Behmanesh M, Nikkhah M, Kane EG. RNAi mediated gene silencing of ITPA using a targeted nanocarrier: Apoptosis induction in SKBR3 cancer cells. Clin Exp Pharmacol Physiol 2018; 44:888-894. [PMID: 28464292 DOI: 10.1111/1440-1681.12776] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2016] [Revised: 04/08/2017] [Accepted: 04/13/2017] [Indexed: 11/28/2022]
Abstract
A pure nucleotide pool is required for high-fidelity DNA replication and prevention of carcinogenesis in living cells. Human inosine triphosphatase (ITPase), encoded by the ITPA gene, plays a critical role in maintaining the purity of the cellular nucleotide pool by excluding nucleotides that enhance mutagenesis. ITPase is a nucleoside triphosphate pyrophosphatase that hydrolyzes the non-canonical nucleotides inosine triphosphate (ITP) and xanthine triphosphate (XTP). The monophosphate products of ITPase reactions are subsequently excluded from the nucleotide pool and the improper substitution of ITP and XTP into DNA and RNA is prevented. Previous studies show that deficiency in ITPA can suppress cellular growth and enhance DNA instability. In this study, we evaluated the influence of effective ITPA down-regulation on the induction of apoptosis in a human cancer cell line using folate-single wall nanotubes (SWNT) as a targeted nanocarrier. We assessed whether SWNT enhances IPTA-siRNA transfection efficiency in cancer cells using folate as a homing device. Since folate receptor is considerably overexpressed in cancer cells, conjugation of SWNTs to folate could enhance their cancer-specific penetrance. We found that nanocarrier mediated ITPA-siRNA transfection into SKBR3 cells caused significant reduction of ITPA mRNA expression level and complete down-regulation of the ITPase protein product. The silencing of ITPA led to promotion of apoptosis in SWNT-treated SKBR3 cancer cells.
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Affiliation(s)
- Fahimeh Charbgoo
- Department of Nanobiotechnology, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran
| | - Mehrdad Behmanesh
- Department of Nanobiotechnology, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran.,Department of Genetics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran
| | - Maryam Nikkhah
- Department of Nanobiotechnology, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran
| | - Eric G Kane
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC, USA
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31
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Peltenburg NC, Bierau J, Bakker JA, Schippers JA, Lowe SH, Paulussen ADC, van den Bosch BJC, Leers MPG, Hansen BE, Verbon A. Erythrocyte Inosine triphosphatase activity: A potential biomarker for adverse events during combination antiretroviral therapy for HIV. PLoS One 2018; 13:e0191069. [PMID: 29329318 PMCID: PMC5766130 DOI: 10.1371/journal.pone.0191069] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 12/26/2017] [Indexed: 12/30/2022] Open
Abstract
The purine analogues tenofovir and abacavir are precursors of potential substrates for the enzyme Inosine 5'-triphosphate pyrophosphohydrolase (ITPase). Here, we investigated the association of ITPase activity and ITPA genotype with the occurrence of adverse events (AEs) during combination antiretroviral therapy (cART) for human immunodeficiency virus (HIV) infection. In 393 adult HIV-seropositive patients, AEs were defined as events that led to stop of cART regimen. ITPase activity ≥4 mmol IMP/mmol Hb/hour was considered as normal. ITPA genotype was determined by testing two ITPA polymorphisms: c.94C>A (p.Pro32Thr, rs1127354) and c.124+21A>C (rs7270101). Logistic regression analysis determined odds ratios for developing AEs. In tenofovir-containing regimens decreased ITPase activity was associated with less AEs (p = 0.01) and longer regimen duration (p = 0.001). In contrast, in abacavir-containing regimens decreased ITPase activity was associated with more AEs (crude p = 0.02) and increased switching of medication due to AEs (p = 0.03). ITPA genotype wt/wt was significantly associated with an increase in the occurrence of AEs in tenofovir-containing regimens. Decreased ITPase activity seems to be protective against occurrence of AEs in tenofovir-containing cART, while it is associated with an increase in AEs in abacavir-containing regimens.
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Affiliation(s)
- N. Chantal Peltenburg
- Department of Internal medicine, Division Infectious Diseases, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Medical Microbiology and Infectious Diseases, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Jörgen Bierau
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Jaap A. Bakker
- Department of Clinical Chemistry and Laboratory Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | - Jolanda A. Schippers
- Department of Integrated Care, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Selwyn H. Lowe
- Department of internal medicine, Division Infectious Diseases, Maastricht University Medical Center, Maastricht, The Netherlands
- Department of Medical Microbiology, School of CAPHRI, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Aimée D. C. Paulussen
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands
| | | | - Mathie P. G. Leers
- Department of Clinical Chemistry & Hematology, Zuyderland Medical Center, Heerlen, The Netherlands
| | - Bettina E. Hansen
- Department of Gastroenterology & Hepatology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Annelies Verbon
- Department of Internal medicine, Division Infectious Diseases, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Medical Microbiology and Infectious Diseases, Erasmus Medical Center, Rotterdam, The Netherlands
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32
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Ji D, Stepchenkova EI, Cui J, Menezes MR, Pavlov YI, Kool ET. Measuring deaminated nucleotide surveillance enzyme ITPA activity with an ATP-releasing nucleotide chimera. Nucleic Acids Res 2017; 45:11515-11524. [PMID: 29036687 PMCID: PMC5714213 DOI: 10.1093/nar/gkx774] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 08/23/2017] [Indexed: 01/24/2023] Open
Abstract
Nucleotide quality surveillance enzymes play important roles in human health, by detecting damaged molecules in the nucleotide pool and deactivating them before they are incorporated into chromosomal DNA or adversely affect metabolism. In particular, deamination of adenine moiety in (deoxy)nucleoside triphosphates, resulting in formation of (d)ITP, can be deleterious, leading to DNA damage, mutagenesis and other harmful cellular effects. The 21.5 kDa human enzyme that mitigates this damage by conversion of (d)ITP to monophosphate, ITPA, has been proposed as a possible therapeutic and diagnostic target for multiple diseases. Measuring the activity of this enzyme is useful both in basic research and in clinical applications involving this pathway, but current methods are nonselective and are not applicable to measurement of the enzyme from cells or tissues. Here, we describe the design and synthesis of an ITPA-specific chimeric dinucleotide (DIAL) that replaces the pyrophosphate leaving group of the native substrate with adenosine triphosphate, enabling sensitive detection via luciferase luminescence signaling. The probe is shown to function sensitively and selectively to quantify enzyme activity in vitro, and can be used to measure the activity of ITPA in bacterial, yeast and human cell lysates.
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Affiliation(s)
- Debin Ji
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA
| | - Elena I Stepchenkova
- The Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA.,Department of Genetics and Biotechnology, Saint-Petersburg State University, St Petersburg, 199034, Russia.,Saint-Petersburg Branch of Vavilov Institute of General Genetics, RAS, St Petersburg, 199034, Russia
| | - Jian Cui
- The Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Miriam R Menezes
- Department of Neurosurgery, University of Texas Health Science Center, Houston, TX 77030, USA
| | - Youri I Pavlov
- The Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA.,Departments of Biochemistry and Molecular Biology; Microbiology and Pathology; Genetics Cell Biology and Anatomy; University of Nebraska Medical Center, Omaha, NE 61818, USA
| | - Eric T Kool
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA
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33
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Koch J, Mayr JA, Alhaddad B, Rauscher C, Bierau J, Kovacs-Nagy R, Coene KLM, Bader I, Holzhacker M, Prokisch H, Venselaar H, Wevers RA, Distelmaier F, Polster T, Leiz S, Betzler C, Strom TM, Sperl W, Meitinger T, Wortmann SB, Haack TB. CAD mutations and uridine-responsive epileptic encephalopathy. Brain 2016; 140:279-286. [PMID: 28007989 DOI: 10.1093/brain/aww300] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 09/14/2016] [Accepted: 10/07/2016] [Indexed: 11/14/2022] Open
Abstract
Unexplained global developmental delay and epilepsy in childhood pose a major socioeconomic burden. Progress in defining the molecular bases does not often translate into effective treatment. Notable exceptions include certain inborn errors of metabolism amenable to dietary intervention. CAD encodes a multifunctional enzyme involved in de novo pyrimidine biosynthesis. Alternatively, pyrimidines can be recycled from uridine. Exome sequencing in three families identified biallelic CAD mutations in four children with global developmental delay, epileptic encephalopathy, and anaemia with anisopoikilocytosis. Two died aged 4 and 5 years after a neurodegenerative disease course. Supplementation of the two surviving children with oral uridine led to immediate cessation of seizures in both. A 4-year-old female, previously in a minimally conscious state, began to communicate and walk with assistance after 9 weeks of treatment. A 3-year-old female likewise showed developmental progress. Blood smears normalized and anaemia resolved. We establish CAD as a gene confidently implicated in this neurometabolic disorder, characterized by co-occurrence of global developmental delay, dyserythropoietic anaemia and seizures. While the natural disease course can be lethal in early childhood, our findings support the efficacy of uridine supplementation, rendering CAD deficiency a treatable neurometabolic disorder and therefore a potential condition for future (genetic) newborn screening.
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Affiliation(s)
- Johannes Koch
- Department of Pediatrics, Salzburger Landeskliniken (SALK) and Paracelsus Medical University (PMU), Salzburg, Austria
| | - Johannes A Mayr
- Department of Pediatrics, Salzburger Landeskliniken (SALK) and Paracelsus Medical University (PMU), Salzburg, Austria
| | - Bader Alhaddad
- Institute of Human Genetics, Technische Universität München, Munich, Germany
| | - Christian Rauscher
- Department of Pediatrics, Salzburger Landeskliniken (SALK) and Paracelsus Medical University (PMU), Salzburg, Austria
| | - Jörgen Bierau
- Department of Clinical Genetics, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Reka Kovacs-Nagy
- Institute of Human Genetics, Technische Universität München, Munich, Germany
| | - Karlien L M Coene
- Translational Metabolic Laboratory, Department of Laboratory Medicine, Radboudumc Nijmegen, The Netherlands.,Center for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboudumc Nijmegen, The Netherlands.,Clinical Laboratory, Catharina Hospital Eindhoven, Eindhoven, The Netherlands
| | - Ingrid Bader
- Department of Pediatrics, Salzburger Landeskliniken (SALK) and Paracelsus Medical University (PMU), Salzburg, Austria
| | - Monika Holzhacker
- Department of Pediatrics, Salzburger Landeskliniken (SALK) and Paracelsus Medical University (PMU), Salzburg, Austria
| | - Holger Prokisch
- Institute of Human Genetics, Technische Universität München, Munich, Germany.,Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany
| | - Hanka Venselaar
- Center for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboudumc Nijmegen, The Netherlands
| | - Ron A Wevers
- Translational Metabolic Laboratory, Department of Laboratory Medicine, Radboudumc Nijmegen, The Netherlands
| | - Felix Distelmaier
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, University Children's Hospital, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | - Tilman Polster
- Department of Paediatric Epileptology, Mara Hospital, Bethel Epilepsy Center, Bielefeld, Germany
| | - Steffen Leiz
- Department of Pediatrics, Salzburger Landeskliniken (SALK) and Paracelsus Medical University (PMU), Salzburg, Austria.,Department of Pediatrics, Salzburger Landeskliniken (SALK) and Paracelsus Medical University (PMU), Salzburg, Austria
| | - Cornelia Betzler
- Department of Pediatrics, Salzburger Landeskliniken (SALK) and Paracelsus Medical University (PMU), Salzburg, Austria
| | - Tim M Strom
- Institute of Human Genetics, Technische Universität München, Munich, Germany.,Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany
| | - Wolfgang Sperl
- Department of Pediatrics, Salzburger Landeskliniken (SALK) and Paracelsus Medical University (PMU), Salzburg, Austria
| | - Thomas Meitinger
- Institute of Human Genetics, Technische Universität München, Munich, Germany.,Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany.,Department of Pediatrics, Salzburger Landeskliniken (SALK) and Paracelsus Medical University (PMU), Salzburg, Austria.,Institute of Human Genetics, Technische Universität München, Munich, Germany
| | - Saskia B Wortmann
- Department of Pediatrics, Salzburger Landeskliniken (SALK) and Paracelsus Medical University (PMU), Salzburg, Austria.,Institute of Human Genetics, Technische Universität München, Munich, Germany.,Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany
| | - Tobias B Haack
- Institute of Human Genetics, Technische Universität München, Munich, Germany .,Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany.,Department of Clinical Genetics, Maastricht University Medical Centre, Maastricht, The Netherlands
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Peltenburg NC, Leers MPG, Bakker JA, Lowe SH, Vroemen WHM, Paulussen ADC, van den Bosch BJC, Bierau J, Verbon A. Inosine Triphosphate Pyrophosphohydrolase Expression: Decreased in Leukocytes of HIV-Infected Patients Using Combination Antiretroviral Therapy. J Acquir Immune Defic Syndr 2016; 73:390-395. [PMID: 27792682 DOI: 10.1097/qai.0000000000001130] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
OBJECTIVE In HIV-infected patients, the enzyme Inosine triphosphate pyrophosphohydrolase (ITPase), involved in purine nucleotide homeostasis, was found to be decreased in erythrocytes. Since purine analogues are pivotal in the HIV treatment, a better understanding of ITPase expression in CD4 lymphocytes may lead to better understanding of nucleotide metabolism and (adverse) effects. DESIGN Cross-sectional, cohort, observational study. METHODS HIV-infected and control patients above 18 years were included. All DNA samples were genotyped for the 2 functional ITPA SNPs; c.94C>A (rs1127354) and g.IVS+21A>C (rs7270101). ITPase expression was determined by flow cytometry in all leukocyte subsets. RESULTS Fifty-nine HIV-infected patients and 50 controls were included. Leukocyte subtype distribution showed no difference in monocytes and granulocytes, but lymphocytes were higher in HIV-infected patients (P < 0.001). ITPase expression was highest in activated monocytes and lowest in lymphocytes. In HIV-infected patients, the percentage of ITPase positive cells was less in all leukocyte and lymphocyte subsets compared with controls (P < 0.01). In HIV-infected patients, 97.4% of CD4 lymphocytes were ITPase positive versus 99.9% in controls (P = 0.002) and 85.9% versus 99.6% of CD8 lymphocytes (P < 0.0001), respectively. Stratification according to genotype revealed no significant differences in ITPase expression in leukocytes in HIV-infected and control patients. CONCLUSIONS HIV-infection seems to be interfering with the nucleotide metabolism in leukocytes, including CD4 lymphocytes, by decreasing ITPase expression, independently of ITPA genotype. Given that active metabolites of purine-analogue reverse transcriptase inhibitors are potential substrates for ITPase, these results warrant further research towards effectiveness and adverse events of purine analogues and ITPase activity.
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Affiliation(s)
- N Chantal Peltenburg
- *Department of Internal Medicine, Division of Infectious Diseases, Erasmus MC, Rotterdam, the Netherlands;†Department of Clinical Chemistry and Hematology, Zuyderland Medical Center, Heerlen, the Netherlands;‡Department of Clinical Chemistry and Laboratory Medicine, Leiden University Medical Center, Leiden, the Netherlands;Departments of §Medical Microbiology;‖Internal Medicine, Division of Infectious Diseases, Research School CAPHRI, Maastricht University Medical Center, Maastricht, the Netherlands;¶Department of Clinical Genetics, Maastricht University Medical Centre, Maastricht, the Netherlands; and#Department of Medical Microbiology and Infectious Diseases, Erasmus MC, Rotterdam, the Netherlands
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35
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Burgis NE. A disease spectrum for ITPA variation: advances in biochemical and clinical research. J Biomed Sci 2016; 23:73. [PMID: 27770805 PMCID: PMC5075207 DOI: 10.1186/s12929-016-0291-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 10/19/2016] [Indexed: 12/15/2022] Open
Abstract
Human ITPase (encoded by the ITPA gene) is a protective enzyme which acts to exclude noncanonical (deoxy)nucleoside triphosphates ((d)NTPs) such as (deoxy)inosine 5′-triphosphate ((d)ITP), from (d)NTP pools. Until the last few years, the importance of ITPase in human health and disease has been enigmatic. In 2009, an article was published demonstrating that ITPase deficiency in mice is lethal. All homozygous null offspring died before weaning as a result of cardiomyopathy due to a defect in the maintenance of quality ATP pools. More recently, a whole exome sequencing project revealed that very rare, severe human ITPA mutation results in early infantile encephalopathy and death. It has been estimated that nearly one third of the human population has an ITPA status which is associated with decreased ITPase activity. ITPA status has been linked to altered outcomes for patients undergoing thiopurine or ribavirin therapy. Thiopurine therapy can be toxic for patients with ITPA polymorphism, however, ITPA polymorphism is associated with improved outcomes for patients undergoing ribavirin treatment. ITPA polymorphism has also been linked to early-onset tuberculosis susceptibility. These data suggest a spectrum of ITPA-related disease exists in human populations. Potentially, ITPA status may affect a large number of patient outcomes, suggesting that modulation of ITPase activity is an important emerging avenue for reducing the number of negative outcomes for ITPA-related disease. Recent biochemical studies have aimed to provide rationale for clinical observations, better understand substrate selectivity and provide a platform for modulation of ITPase activity.
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Affiliation(s)
- Nicholas E Burgis
- Department of Chemistry and Biochemistry, Eastern Washington University, 226 Science Building, Cheney, WA, 99004, USA.
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Yoneshima Y, Abolhassani N, Iyama T, Sakumi K, Shiomi N, Mori M, Shiomi T, Noda T, Tsuchimoto D, Nakabeppu Y. Deoxyinosine triphosphate induces MLH1/PMS2- and p53-dependent cell growth arrest and DNA instability in mammalian cells. Sci Rep 2016; 6:32849. [PMID: 27618981 PMCID: PMC5020429 DOI: 10.1038/srep32849] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 08/16/2016] [Indexed: 12/30/2022] Open
Abstract
Deoxyinosine (dI) occurs in DNA either by oxidative deamination of a previously incorporated deoxyadenosine residue or by misincorporation of deoxyinosine triphosphate (dITP) from the nucleotide pool during replication. To exclude dITP from the pool, mammals possess specific hydrolysing enzymes, such as inosine triphosphatase (ITPA). Previous studies have shown that deficiency in ITPA results in cell growth suppression and DNA instability. To explore the mechanisms of these phenotypes, we analysed ITPA-deficient human and mouse cells. We found that both growth suppression and accumulation of single-strand breaks in nuclear DNA of ITPA-deficient cells depended on MLH1/PMS2. The cell growth suppression of ITPA-deficient cells also depended on p53, but not on MPG, ENDOV or MSH2. ITPA deficiency significantly increased the levels of p53 protein and p21 mRNA/protein, a well-known target of p53, in an MLH1-dependent manner. Furthermore, MLH1 may also contribute to cell growth arrest by increasing the basal level of p53 activity.
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Affiliation(s)
- Yasuto Yoneshima
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8581, Japan
- Research Institute for Diseases of the Chest, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8581, Japan
| | - Nona Abolhassani
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8581, Japan
| | - Teruaki Iyama
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8581, Japan
| | - Kunihiko Sakumi
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8581, Japan
- Research Center for Nucleotide Pool, Kyushu University, Fukuoka 812-8581, Japan
| | - Naoko Shiomi
- National Institute of Radiological Sciences, Chiba 263-8555, Japan
| | - Masahiko Mori
- National Institute of Radiological Sciences, Chiba 263-8555, Japan
| | - Tadahiro Shiomi
- National Institute of Radiological Sciences, Chiba 263-8555, Japan
| | - Tetsuo Noda
- Cancer Institute, Japanese Foundation for Cancer Research, Tokyo 135-8550, Japan
| | - Daisuke Tsuchimoto
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8581, Japan
- Research Center for Nucleotide Pool, Kyushu University, Fukuoka 812-8581, Japan
| | - Yusaku Nakabeppu
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8581, Japan
- Research Center for Nucleotide Pool, Kyushu University, Fukuoka 812-8581, Japan
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