1
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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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2
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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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3
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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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4
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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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5
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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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6
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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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7
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Straube H, Straube J, Rinne J, Fischer L, Niehaus M, Witte CP, Herde M. An inosine triphosphate pyrophosphatase safeguards plant nucleic acids from aberrant purine nucleotides. THE NEW PHYTOLOGIST 2023; 237:1759-1775. [PMID: 36464781 DOI: 10.1111/nph.18656] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 11/22/2022] [Indexed: 06/17/2023]
Abstract
In plants, inosine is enzymatically introduced in some tRNAs, but not in other RNAs or DNA. Nonetheless, our data show that RNA and DNA from Arabidopsis thaliana contain (deoxy)inosine, probably derived from nonenzymatic adenosine deamination in nucleic acids and usage of (deoxy)inosine triphosphate (dITP and ITP) during nucleic acid synthesis. We combined biochemical approaches, LC-MS, as well as RNA-Seq to characterize a plant INOSINE TRIPHOSPHATE PYROPHOSPHATASE (ITPA) from A. thaliana, which is conserved in many organisms, and investigated the sources of deaminated purine nucleotides in plants. Inosine triphosphate pyrophosphatase dephosphorylates deaminated nucleoside di- and triphosphates to the respective monophosphates. ITPA loss-of-function causes inosine di- and triphosphate accumulation in vivo and an elevated inosine and deoxyinosine content in RNA and DNA, respectively, as well as salicylic acid (SA) accumulation, early senescence, and upregulation of transcripts associated with immunity and senescence. Cadmium-induced oxidative stress and biochemical inhibition of the INOSINE MONOPHOSPHATE DEHYDROGENASE leads to more IDP and ITP in the wild-type (WT), and this effect is enhanced in itpa mutants, suggesting that ITP originates from ATP deamination and IMP phosphorylation. Inosine triphosphate pyrophosphatase is part of a molecular protection system in plants, preventing the accumulation of (d)ITP and its usage for nucleic acid synthesis.
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Affiliation(s)
- Henryk Straube
- Department of Molecular Nutrition and Biochemistry of Plants, Leibniz Universität Hannover, Hannover, 30419, Germany
| | - Jannis Straube
- Department of Molecular Plant Breeding, Leibniz Universität Hannover, Hannover, 30419, Germany
| | - Jannis Rinne
- Department of Molecular Nutrition and Biochemistry of Plants, Leibniz Universität Hannover, Hannover, 30419, Germany
| | - Lisa Fischer
- Department of Molecular Nutrition and Biochemistry of Plants, Leibniz Universität Hannover, Hannover, 30419, Germany
| | - Markus Niehaus
- Department of Molecular Nutrition and Biochemistry of Plants, Leibniz Universität Hannover, Hannover, 30419, Germany
| | - Claus-Peter Witte
- Department of Molecular Nutrition and Biochemistry of Plants, Leibniz Universität Hannover, Hannover, 30419, Germany
| | - Marco Herde
- Department of Molecular Nutrition and Biochemistry of Plants, Leibniz Universität Hannover, Hannover, 30419, Germany
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8
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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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9
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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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10
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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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11
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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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12
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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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13
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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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14
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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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15
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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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16
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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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17
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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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18
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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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Brodehl A, Ebbinghaus H, Deutsch MA, Gummert J, Gärtner A, Ratnavadivel S, Milting H. Human Induced Pluripotent Stem-Cell-Derived Cardiomyocytes as Models for Genetic Cardiomyopathies. Int J Mol Sci 2019; 20:ijms20184381. [PMID: 31489928 PMCID: PMC6770343 DOI: 10.3390/ijms20184381] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 08/29/2019] [Accepted: 09/03/2019] [Indexed: 12/17/2022] Open
Abstract
In the last few decades, many pathogenic or likely pathogenic genetic mutations in over hundred different genes have been described for non-ischemic, genetic cardiomyopathies. However, the functional knowledge about most of these mutations is still limited because the generation of adequate animal models is time-consuming and challenging. Therefore, human induced pluripotent stem cells (iPSCs) carrying specific cardiomyopathy-associated mutations are a promising alternative. Since the original discovery that pluripotency can be artificially induced by the expression of different transcription factors, various patient-specific-induced pluripotent stem cell lines have been generated to model non-ischemic, genetic cardiomyopathies in vitro. In this review, we describe the genetic landscape of non-ischemic, genetic cardiomyopathies and give an overview about different human iPSC lines, which have been developed for the disease modeling of inherited cardiomyopathies. We summarize different methods and protocols for the general differentiation of human iPSCs into cardiomyocytes. In addition, we describe methods and technologies to investigate functionally human iPSC-derived cardiomyocytes. Furthermore, we summarize novel genome editing approaches for the genetic manipulation of human iPSCs. This review provides an overview about the genetic landscape of inherited cardiomyopathies with a focus on iPSC technology, which might be of interest for clinicians and basic scientists interested in genetic cardiomyopathies.
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Affiliation(s)
- Andreas Brodehl
- Erich and Hanna Klessmann Institute, Heart and Diabetes Center NRW, University Hospital of the Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
| | - Hans Ebbinghaus
- Erich and Hanna Klessmann Institute, Heart and Diabetes Center NRW, University Hospital of the Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
| | - Marcus-André Deutsch
- Department of Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, University Hospital Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
| | - Jan Gummert
- Erich and Hanna Klessmann Institute, Heart and Diabetes Center NRW, University Hospital of the Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
- Department of Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, University Hospital Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
| | - Anna Gärtner
- Erich and Hanna Klessmann Institute, Heart and Diabetes Center NRW, University Hospital of the Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
| | - Sandra Ratnavadivel
- Erich and Hanna Klessmann Institute, Heart and Diabetes Center NRW, University Hospital of the Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
| | - Hendrik Milting
- Erich and Hanna Klessmann Institute, Heart and Diabetes Center NRW, University Hospital of the Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
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