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Maekawa S, Nishikawa I, Horiguchi G. Impaired inosine monophosphate dehydrogenase leads to plant-specific ribosomal stress responses in Arabidopsis thaliana. JOURNAL OF PLANT RESEARCH 2024:10.1007/s10265-024-01578-5. [PMID: 39235732 DOI: 10.1007/s10265-024-01578-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2024] [Accepted: 08/23/2024] [Indexed: 09/06/2024]
Abstract
Nucleotides are the building blocks of living organisms and their biosynthesis must be tightly regulated. Inosine monophosphate dehydrogenase (IMPDH) is a rate-limiting enzyme in GTP synthesis that is essential for biological activities, such as RNA synthesis. In animals, the suppression of IMPDH function causes ribosomal stress (also known as nucleolar stress), a disorder in ribosome biogenesis that results in cell proliferation defects and apoptosis. Despite its importance, plant IMPDH has not been analyzed in detail. Therefore, we analyzed the phenotypes of mutants of the two IMPDH genes in Arabidopsis thaliana and investigated their relationship with ribosomal stress. Double mutants of IMPDH1 and IMPDH2 were lethal, and only the impdh2 mutants showed growth defects and transient chlorophyll deficiency. These results suggested that IMPDH1 and IMPDH2 are redundant and essential, whereas IMPDH2 has a crucial role. In addition, the impdh2 mutants showed a reduction in nucleolus size and resistance to several translation inhibitors, which is a known response to ribosomal stress. Furthermore, the IMPDH1/impdh1 impdh2 mutants showed more severe growth defects and phenotypes such as reduced plastid rRNA levels and abnormal processing patterns than the impdh2 mutants. Finally, multiple mutations of impdh with as2, which has abnormal leaf polarity, caused the development of needle-like leaves because of the enhancement of the as2 phenotype, which is a typical effect observed in mutants of genes involved in ribosome biogenesis. These results indicated that IMPDH is closely related to ribosome biogenesis, and that mutations in the genes lead to not only known responses to ribosomal stress, but also plant-specific responses.
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Affiliation(s)
- Shugo Maekawa
- Institute of Natural Sciences, Senshu University, Higashimita 2-1-1, Tama, Kawasaki, Kanagawa, 214-8580, Japan.
- Department of Life Science, College of Science, Rikkyo University, Toshima, Tokyo, 171-8501, Japan.
| | - Ikuto Nishikawa
- Department of Life Science, College of Science, Rikkyo University, Toshima, Tokyo, 171-8501, Japan
- Medical Institute of Bioregulation, Kyushu University, Fukuoka City, Fukuoka, 812-8582, Japan
| | - Gorou Horiguchi
- Department of Life Science, College of Science, Rikkyo University, Toshima, Tokyo, 171-8501, Japan
- Research Center for Life Science, College of Science, Rikkyo University, Toshima, Tokyo, 171-8501, Japan
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2
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Abdel-Fattah WR, Carlsson M, Hu GZ, Singh A, Vergara A, Aslam R, Ronne H, Björklund S. Growth-regulated co-occupancy of Mediator and Lsm3 at intronic ribosomal protein genes. Nucleic Acids Res 2024; 52:6220-6233. [PMID: 38613396 PMCID: PMC11194063 DOI: 10.1093/nar/gkae266] [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: 01/08/2024] [Revised: 03/22/2024] [Accepted: 04/01/2024] [Indexed: 04/14/2024] Open
Abstract
Mediator is a well-known transcriptional co-regulator and serves as an adaptor between gene-specific regulatory proteins and RNA polymerase II. Studies on the chromatin-bound form of Mediator revealed interactions with additional protein complexes involved in various transcription-related processes, such as the Lsm2-8 complex that is part of the spliceosomal U6 small nuclear ribonucleoprotein complex. Here, we employ Chromatin Immunoprecipitation sequencing (ChIP-seq) of chromatin associated with the Lsm3 protein and the Med1 or Med15 Mediator subunits. We identify 86 genes co-occupied by both Lsm3 and Mediator, of which 73 were intron-containing ribosomal protein genes. In logarithmically growing cells, Mediator primarily binds to their promoter regions but also shows a second, less pronounced occupancy at their 3'-exons. During the late exponential phase, we observe a near-complete transition of Mediator from these promoters to a position in their 3'-ends, overlapping the Lsm3 binding sites ∼250 bp downstream of their last intron-exon boundaries. Using an unbiased RNA sequencing approach, we show that transition of Mediator from promoters to the last exon of these genes correlates to reduction of both their messenger RNA levels and splicing ratios, indicating that the Mediator and Lsm complexes cooperate to control growth-regulated expression of intron-containing ribosomal protein genes at the levels of transcription and splicing.
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Affiliation(s)
- Wael R Abdel-Fattah
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-901 87 Umeå, Sweden
| | - Mattias Carlsson
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Box 7026, SE-750 07 Uppsala, Sweden
| | - Guo-Zhen Hu
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Box 7026, SE-750 07 Uppsala, Sweden
| | - Ajeet Singh
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-901 87 Umeå, Sweden
| | - Alexander Vergara
- Department of Plant Physiology, Umeå University, SE-901 87 Umeå, Sweden
| | - Rameen Aslam
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-901 87 Umeå, Sweden
| | - Hans Ronne
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Box 7026, SE-750 07 Uppsala, Sweden
| | - Stefan Björklund
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-901 87 Umeå, Sweden
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3
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Nabi Afjadi M, Yazdanparast R, Barzegari E. The Impact of Terminal Peptide Extensions of Retinal Inosine 5´Monophosphate Dehydrogenase 1 Isoforms on their DNA-binding Activities. Protein J 2024; 43:592-602. [PMID: 38733555 DOI: 10.1007/s10930-024-10202-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/30/2024] [Indexed: 05/13/2024]
Abstract
The main structural difference between the mutation-susceptible retinal isoforms of inosine 5´-monophosphate dehydrogenase-1 (IMPDH-1) with the canonical form resides in the C- and N-terminal peptide extensions with unknown structural/functional impacts. In this report, we aimed to experimentally evaluate the functional impact of these extensions on the specific/non-specific single-stranded DNA (ssDNA)-binding activities relative to those of the canonical form. Our in silico findings indicated the possible contribution of the C-terminal segment to the reduced flexibility of the Bateman domain of the enzyme. In addition, the in silico data indicated that the N-terminal tail acts by altering the distance between the tetramers in the concave octamer complex (the native form) of the enzyme. The overall impact of these predicted structural variations became evident, first, through higher Km values with respect to either of the substrates relative to the canonical isoform, as reported previously (Andashti et al. in Mol Cell Biochem 465(1):155-164, 2020). Secondary, the binding of the recombinant mouse retinal isoform IMPDH1 (603) to its specific Rhodopsin target gene was significantly augmented while its binding to non-specific ssDNA was lower than that of the canonical isoform. The DNA-binding activity of the other mouse retinal isoform, IMPDH1(546), to specific and non-specific ssDNA was lower than that of the canonical form most probably due to the in silico predicted rigidity created in the Bateman domain by the C-terminal peptide extension. Furthermore, the DNA binding to the Rhodopsin target gene by each of the IMPDH isoforms influenced in the presence of GTP (Guanosine triphosphate) and ATP (Adenosine triphosphate).
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Affiliation(s)
- Mohsen Nabi Afjadi
- Institute of Biochemistry and Biophysics, University of Tehran, P. O. Box 13145-1384, Tehran, Iran
| | - Razieh Yazdanparast
- Institute of Biochemistry and Biophysics, University of Tehran, P. O. Box 13145-1384, Tehran, Iran.
| | - Ebrahim Barzegari
- Institute of Biochemistry and Biophysics, University of Tehran, P. O. Box 13145-1384, Tehran, Iran
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4
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Sakti DH, Cornish EE, Nash BM, Jamieson RV, Grigg JR. IMPDH1-associated autosomal dominant retinitis pigmentosa: natural history of novel variant Lys314Gln and a comprehensive literature search. Ophthalmic Genet 2023; 44:437-455. [PMID: 37259572 DOI: 10.1080/13816810.2023.2215310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 05/11/2023] [Accepted: 05/14/2023] [Indexed: 06/02/2023]
Abstract
BACKGROUND Inosine monophosphate dehydrogenase (IMPDH) is a key regulatory enzyme in the de novo synthesis of the purine base guanine. Mutations in the inosine monophosphate dehydrogenase 1 gene (IMPDH1) are causative for RP10 autosomal dominant retinitis pigmentosa (adRP). This study reports a novel variant in a family with IMPDH1-associated retinopathy. We also performed a comprehensive review of all reported IMPDH1 disease causing variants with their associated phenotype. MATERIALS AND METHODS Multimodal imaging and functional studies documented the phenotype including best-corrected visual acuity (BCVA), fundus photograph, fundus autofluorescence (FAF), full field electroretinogram (ffERG), optical coherence tomography (OCT) and visual field (VF) data were collected. A literature search was performed in the PubMed and LOVD repositories. RESULTS We report 3 cases from a 2-generation family with a novel heterozygous likely pathogenic variant p. (Lys314Gln) (exon 10). The ophthalmic phenotype showed diffuse outer retinal atrophy with mild pigmentary changes with sparse pigmentary changes. FAF showed early macular involvement with macular hyperautofluorescence (hyperAF) surrounded by hypoAF. Foveal ellipsoid zone island can be found in the youngest patient but not in the older ones. The literature review identified a further 56 heterozygous, 1 compound heterozygous, and 2 homozygous variant. The heterozygous group included 43 missense, 3 in-frame, 1 nonsense, 2 frameshift, 1 synonymous, and 6 intronic variants. Exon 10 was noted as a hotspot harboring 18 variants. CONCLUSIONS We report a novel IMPDH1 variant. IMPDH1-associated retinopathy presents most frequently in the first decade of life with early macular involvement.
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Affiliation(s)
- Dhimas H Sakti
- Save Sight Institute, University of Sydney, Sydney, New South Wales, Australia
- Department of Ophthalmology, Faculty of Medicine, Public Health and Nursing, Universitas Gadjah Mada, Yogyakarta, Indonesia
| | - Elisa E Cornish
- Save Sight Institute, University of Sydney, Sydney, New South Wales, Australia
- Eye Genetics Research Unit, Children's Medical Research Institute, The Children's Hospital at Westmead, Sydney, New South Wales, Australia
| | - Benjamin M Nash
- Eye Genetics Research Unit, Children's Medical Research Institute, The Children's Hospital at Westmead, Sydney, New South Wales, Australia
- Sydney Genome Diagnostics, Western Sydney Genetics Program, Sydney Children's Hospitals Network, Sydney, New South Wales, Australia
| | - Robyn V Jamieson
- Eye Genetics Research Unit, Children's Medical Research Institute, The Children's Hospital at Westmead, Sydney, New South Wales, Australia
| | - John R Grigg
- Save Sight Institute, University of Sydney, Sydney, New South Wales, Australia
- Eye Genetics Research Unit, Children's Medical Research Institute, The Children's Hospital at Westmead, Sydney, New South Wales, Australia
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5
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Camici M, Garcia-Gil M, Allegrini S, Pesi R, Bernardini G, Micheli V, Tozzi MG. Inborn Errors of Purine Salvage and Catabolism. Metabolites 2023; 13:787. [PMID: 37512494 PMCID: PMC10383617 DOI: 10.3390/metabo13070787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 06/20/2023] [Accepted: 06/21/2023] [Indexed: 07/30/2023] Open
Abstract
Cellular purine nucleotides derive mainly from de novo synthesis or nucleic acid turnover and, only marginally, from dietary intake. They are subjected to catabolism, eventually forming uric acid in humans, while bases and nucleosides may be converted back to nucleotides through the salvage pathways. Inborn errors of the purine salvage pathway and catabolism have been described by several researchers and are usually referred to as rare diseases. Since purine compounds play a fundamental role, it is not surprising that their dysmetabolism is accompanied by devastating symptoms. Nevertheless, some of these manifestations are unexpected and, so far, have no explanation or therapy. Herein, we describe several known inborn errors of purine metabolism, highlighting their unexplained pathological aspects. Our intent is to offer new points of view on this topic and suggest diagnostic tools that may possibly indicate to clinicians that the inborn errors of purine metabolism may not be very rare diseases after all.
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Affiliation(s)
- Marcella Camici
- Unità di Biochimica, Dipartimento di Biologia, Università di Pisa, Via San Zeno 51, 56127 Pisa, Italy
| | - Mercedes Garcia-Gil
- Unità di Fisiologia Generale, Dipartimento di Biologia, Università di Pisa, Via San Zeno 31, 56127 Pisa, Italy
- CISUP, Centro per l'Integrazione Della Strumentazione Dell'Università di Pisa, 56127 Pisa, Italy
- Centro di Ricerca Interdipartimentale Nutrafood "Nutraceuticals and Food for Health", Università di Pisa, 56126 Pisa, Italy
| | - Simone Allegrini
- Unità di Biochimica, Dipartimento di Biologia, Università di Pisa, Via San Zeno 51, 56127 Pisa, Italy
- CISUP, Centro per l'Integrazione Della Strumentazione Dell'Università di Pisa, 56127 Pisa, Italy
- Centro di Ricerca Interdipartimentale Nutrafood "Nutraceuticals and Food for Health", Università di Pisa, 56126 Pisa, Italy
| | - Rossana Pesi
- Unità di Biochimica, Dipartimento di Biologia, Università di Pisa, Via San Zeno 51, 56127 Pisa, Italy
| | - Giulia Bernardini
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena, Via A. Moro 2, 53100 Siena, Italy
| | - Vanna Micheli
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena, Via A. Moro 2, 53100 Siena, Italy
- LND Famiglie Italiane ODV-Via Giovanetti 15-20, 16149 Genova, Italy
| | - Maria Grazia Tozzi
- Unità di Biochimica, Dipartimento di Biologia, Università di Pisa, Via San Zeno 51, 56127 Pisa, Italy
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Yazdani M, Zamani J, Fatemi SSA. Identification of a potent dual-function inhibitor for hIMPDH isoforms by computer-aided drug discovery approaches. Front Pharmacol 2022; 13:977568. [PMID: 36386211 PMCID: PMC9643795 DOI: 10.3389/fphar.2022.977568] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 09/29/2022] [Indexed: 11/19/2023] Open
Abstract
Inosine monophosphate dehydrogenase (IMPDH) is a key enzyme in de novo biosynthesis of purine nucleotides. Due to this important role, it is a great target to drug discovery for a wide range of activities, especially immunosuppressant in heart and kidney transplantation. Both human IMPDH isoforms are expressed in stimulated lymphocytes. In addition to the side effects of existing drugs, previous studies have mainly focused on the type II isoform. In this study, virtual screening and computer-aided approaches were employed to identify potential drugs with simultaneous inhibitory effects on both human IMPDH isoforms. After Re-docking, Double-step docking, and identification of virtual hits based on the PLANTS scoring function, drug-likeness and ADME-Tox assessments of the topmost ligands were performed. Following further evaluation, the best ligand was selected and, in complex with both isoforms, simulated in monomeric and tetrameric forms using molecular dynamics to evaluate its stability and binding pattern. The results showed a potential drug candidate [(S)-N-(3-hydroxy-1-(4-hydroxyphenyl) propyl)-2-(3-methyl-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl) acetamide] with a high inhibitory effect on the two human IMPDH isoforms. This drug-like inhibitor could potentially serve as an immunosuppressant to prevent transplant rejection response by inhibiting B- and T-lymphocyte proliferation. In addition, its effect can be evaluated in various therapeutic targets in which IMPDH is known as a therapeutic target, especially in Covid-19 patients.
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Affiliation(s)
- Meysam Yazdani
- Department of Systems Biotechnology, Institute of Industrial and Environmental Biotechnology, National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran
| | - Javad Zamani
- Department of Plant Molecular Biotechnology, Institute of Agricultural Biotechnology, National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran
| | - Seyed Safa-Ali Fatemi
- Department of Systems Biotechnology, Institute of Industrial and Environmental Biotechnology, National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran
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7
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Chang CC, Peng M, Zhong J, Zhang Z, Keppeke GD, Sung LY, Liu JL. Molecular crowding facilitates bundling of IMPDH polymers and cytoophidium formation. Cell Mol Life Sci 2022; 79:420. [PMID: 35833994 PMCID: PMC11072341 DOI: 10.1007/s00018-022-04448-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 06/14/2022] [Accepted: 06/21/2022] [Indexed: 11/29/2022]
Abstract
The cytoophidium is a unique type of membraneless compartment comprising of filamentous protein polymers. Inosine monophosphate dehydrogenase (IMPDH) catalyzes the rate-limiting step of de novo GTP biosynthesis and plays critical roles in active cell metabolism. However, the molecular regulation of cytoophidium formation is poorly understood. Here we show that human IMPDH2 polymers bundle up to form cytoophidium-like aggregates in vitro when macromolecular crowders are present. The self-association of IMPDH polymers is suggested to rely on electrostatic interactions. In cells, the increase of molecular crowding with hyperosmotic medium induces cytoophidia, while the decrease of that by the inhibition of RNA synthesis perturbs cytoophidium assembly. In addition to IMPDH, CTPS and PRPS cytoophidium could be also induced by hyperosmolality, suggesting a universal phenomenon of cytoophidium-forming proteins. Finally, our results indicate that the cytoophidium can prolong the half-life of IMPDH, which is proposed to be one of conserved functions of this subcellular compartment.
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Affiliation(s)
- Chia-Chun Chang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
- Institute of Biotechnology, National Taiwan University, Taipei, 106, Taiwan
| | - Min Peng
- Institute of Biotechnology, National Taiwan University, Taipei, 106, Taiwan
| | - Jiale Zhong
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Ziheng Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Gerson Dierley Keppeke
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
- Rheumatology Division, Escola Paulista de Medicina, Universidade Federal de Sao Paulo, Sao Paulo, SP, 04023-062, Brazil
| | - Li-Ying Sung
- Institute of Biotechnology, National Taiwan University, Taipei, 106, Taiwan
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 115, Taiwan
| | - Ji-Long Liu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, UK.
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8
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Fernández-Justel D, Marcos-Alcalde Í, Abascal F, Vidaña N, Gómez-Puertas P, Jiménez A, Revuelta JL, Buey RM. Diversity of mechanisms to control bacterial GTP homeostasis by the mutually exclusive binding of adenine and guanine nucleotides to IMP dehydrogenase. Protein Sci 2022; 31:e4314. [PMID: 35481629 PMCID: PMC9462843 DOI: 10.1002/pro.4314] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 03/21/2022] [Accepted: 04/06/2022] [Indexed: 02/06/2023]
Abstract
IMP dehydrogenase(IMPDH) is an essential enzyme that catalyzes the rate‐limiting step in the guanine nucleotide pathway. In eukaryotic cells, GTP binding to the regulatory domain allosterically controls the activity of IMPDH by a mechanism that is fine‐tuned by post‐translational modifications and enzyme polymerization. Nonetheless, the mechanisms of regulation of IMPDH in bacterial cells remain unclear. Using biochemical, structural, and evolutionary analyses, we demonstrate that, in most bacterial phyla, (p)ppGpp compete with ATP to allosterically modulate IMPDH activity by binding to a, previously unrecognized, conserved high affinity pocket within the regulatory domain. This pocket was lost during the evolution of Proteobacteria, making their IMPDHs insensitive to these alarmones. Instead, most proteobacterial IMPDHs evolved to be directly modulated by the balance between ATP and GTP that compete for the same allosteric binding site. Altogether, we demonstrate that the activity of bacterial IMPDHs is allosterically modulated by a universally conserved nucleotide‐controlled conformational switch that has divergently evolved to adapt to the specific particularities of each organism. These results reconcile the reported data on the crosstalk between (p)ppGpp signaling and the guanine nucleotide biosynthetic pathway and reinforce the essential role of IMPDH allosteric regulation on bacterial GTP homeostasis. PDB Code(s): 7PJI and 7PMZ;
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Affiliation(s)
- David Fernández-Justel
- Metabolic Engineering Group, Department of Microbiology and Genetics, Universidad de Salamanca, Salamanca, Spain
| | - Íñigo Marcos-Alcalde
- Molecular Modeling Group, Centro de Biología Molecular Severo Ochoa, CBMSO (CSIC-UAM), Madrid, Spain.,Biosciences Research Institute, School of Experimental Sciences, Universidad Francisco de Vitoria, Madrid, Spain
| | | | - Nerea Vidaña
- Metabolic Engineering Group, Department of Microbiology and Genetics, Universidad de Salamanca, Salamanca, Spain
| | - Paulino Gómez-Puertas
- Molecular Modeling Group, Centro de Biología Molecular Severo Ochoa, CBMSO (CSIC-UAM), Madrid, Spain
| | - Alberto Jiménez
- Metabolic Engineering Group, Department of Microbiology and Genetics, Universidad de Salamanca, Salamanca, Spain
| | - José L Revuelta
- Metabolic Engineering Group, Department of Microbiology and Genetics, Universidad de Salamanca, Salamanca, Spain
| | - Rubén M Buey
- Metabolic Engineering Group, Department of Microbiology and Genetics, Universidad de Salamanca, Salamanca, Spain
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9
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IMPDH dysregulation in disease: a mini review. Biochem Soc Trans 2022; 50:71-82. [PMID: 35191957 PMCID: PMC9022972 DOI: 10.1042/bst20210446] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 01/24/2022] [Accepted: 01/26/2022] [Indexed: 12/20/2022]
Abstract
Inosine-5′-monophosphate dehydrogenase (IMPDH) is a highly conserved enzyme in purine metabolism that is tightly regulated on multiple levels. IMPDH has a critical role in purine biosynthesis, where it regulates flux at the branch point between adenine and guanine nucleotide synthesis, but it also has a role in transcription regulation and other moonlighting functions have been described. Vertebrates have two isoforms, IMPDH1 and IMPDH2, and point mutations in each are linked to human disease. Mutations in IMPDH2 in humans are associated with neurodevelopmental disease, but the effects of mutations at the enzyme level have not yet been characterized. Mutations in IMPDH1 lead to retinal degeneration in humans, and recent studies have characterized how they cause functional defects in regulation. IMPDH1 is expressed as two unique splice variants in the retina, a tissue with very high and specific demands for purine nucleotides. Recent studies have revealed functional differences among splice variants, demonstrating that retinal variants up-regulate guanine nucleotide synthesis by reducing sensitivity to feedback inhibition by downstream products. A better understanding of the role of IMPDH1 in the retina and the characterization of an animal disease model will be critical for determining the molecular mechanism of IMPDH1-associated blindness.
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10
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Burrell AL, Nie C, Said M, Simonet JC, Fernández-Justel D, Johnson MC, Quispe J, Buey RM, Peterson JR, Kollman JM. IMPDH1 retinal variants control filament architecture to tune allosteric regulation. Nat Struct Mol Biol 2022; 29:47-58. [PMID: 35013599 PMCID: PMC9044917 DOI: 10.1038/s41594-021-00706-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 11/23/2021] [Indexed: 01/06/2023]
Abstract
Inosine-5'-monophosphate dehydrogenase (IMPDH), a key regulatory enzyme in purine nucleotide biosynthesis, dynamically assembles filaments in response to changes in metabolic demand. Humans have two isoforms: IMPDH2 filaments reduce sensitivity to feedback inhibition, while IMPDH1 assembly remains uncharacterized. IMPDH1 plays a unique role in retinal metabolism, and point mutants cause blindness. Here, in a series of cryogenic-electron microscopy structures we show that human IMPDH1 assembles polymorphic filaments with different assembly interfaces in extended and compressed states. Retina-specific splice variants introduce structural elements that reduce sensitivity to GTP inhibition, including stabilization of the extended filament form. Finally, we show that IMPDH1 disease mutations fall into two classes: one disrupts GTP regulation and the other has no effect on GTP regulation or filament assembly. These findings provide a foundation for understanding the role of IMPDH1 in retinal function and disease and demonstrate the diverse mechanisms by which metabolic enzyme filaments are allosterically regulated.
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Affiliation(s)
- Anika L Burrell
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Chuankai Nie
- Department of Biochemistry, University of Washington, Seattle, WA, USA
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, USA
| | - Meerit Said
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Jacqueline C Simonet
- Cancer Epigenetics and Signaling Program, Fox Chase Cancer Center, Philadelphia, PA, USA
- Department of Biology, Arcadia University, Glenside, PA, USA
| | - David Fernández-Justel
- Metabolic Engineering Group, Departamento de Microbiología y Genética, Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain
| | - Matthew C Johnson
- Department of Biochemistry, University of Washington, Seattle, WA, USA
- Department of Structural Biology, Genentech, South San Francisco, CA, USA
| | - Joel Quispe
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Rubén M Buey
- Metabolic Engineering Group, Departamento de Microbiología y Genética, Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain
| | - Jeffrey R Peterson
- Cancer Epigenetics and Signaling Program, Fox Chase Cancer Center, Philadelphia, PA, USA
| | - Justin M Kollman
- Department of Biochemistry, University of Washington, Seattle, WA, USA.
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11
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Cleghorn WM, Burrell AL, Giarmarco MM, Brock DC, Wang Y, Chambers ZS, Du J, Kollman JM, Brockerhoff SE. A highly conserved zebrafish IMPDH retinal isoform produces the majority of guanine and forms dynamic protein filaments in photoreceptor cells. J Biol Chem 2022; 298:101441. [PMID: 34813793 PMCID: PMC8688572 DOI: 10.1016/j.jbc.2021.101441] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 11/12/2021] [Accepted: 11/13/2021] [Indexed: 12/18/2022] Open
Abstract
Inosine monophosphate dehydrogenase (IMPDH) is a key regulatory enzyme in the de novo synthesis of the purine base guanine. Dominant mutations in human IMPDH1 cause photoreceptor degeneration for reasons that are unknown. Here, we sought to provide some foundational information on Impdh1a in the zebrafish retina. We found that in zebrafish, gene subfunctionalization due to ancestral duplication resulted in a predominant retinal variant expressed exclusively in rod and cone photoreceptors. This variant is structurally and functionally similar to the human IMPDH1 retinal variant and shares a reduced sensitivity to GTP-mediated inhibition. We also demonstrated that Impdh1a forms prominent protein filaments in vitro and in vivo in both rod and cone photoreceptor cell bodies, synapses, and to a lesser degree, in outer segments. These filaments changed length and cellular distribution throughout the day consistent with diurnal changes in both mRNA and protein levels. The loss of Impdh1a resulted in a substantial reduction of guanine levels, although cellular morphology and cGMP levels remained normal. Our findings demonstrate a significant role for IMPDH1 in photoreceptor guanine production and provide fundamental new information on the details of this protein in the zebrafish retina.
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Affiliation(s)
- Whitney M Cleghorn
- Department of Biochemistry, University of Washington, Seattle, Washington, USA; Department of Ophthalmology, University of Washington, Seattle, Washington, USA
| | - Anika L Burrell
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
| | | | - Daniel C Brock
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
| | - Yekai Wang
- Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, West Virginia, USA; Department of Biochemistry, West Virginia University, Morgantown, West Virginia, USA
| | - Zachary S Chambers
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
| | - Jianhai Du
- Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, West Virginia, USA; Department of Biochemistry, West Virginia University, Morgantown, West Virginia, USA
| | - Justin M Kollman
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
| | - Susan E Brockerhoff
- Department of Biochemistry, University of Washington, Seattle, Washington, USA; Department of Ophthalmology, University of Washington, Seattle, Washington, USA.
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12
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Abstract
CoVID-19 is a multi-symptomatic disease which has made a global impact due to its ability to spread rapidly, and its relatively high mortality rate. Beyond the heroic efforts to develop vaccines, which we do not discuss herein, the response of scientists and clinicians to this complex problem has reflected the need to detect CoVID-19 rapidly, to diagnose patients likely to show adverse symptoms, and to treat severe and critical CoVID-19. Here we aim to encapsulate these varied and sometimes conflicting approaches and the resulting data in terms of chemistry and biology. In the process we highlight emerging concepts, and potential future applications that may arise out of this immense effort.
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Affiliation(s)
| | - Yimon Aye
- Swiss Federal Institute of Technology in Lausanne (EPFL)1015LausanneSwitzerland
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13
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Muskhelishvili G, Sobetzko P, Mehandziska S, Travers A. Composition of Transcription Machinery and Its Crosstalk with Nucleoid-Associated Proteins and Global Transcription Factors. Biomolecules 2021; 11:biom11070924. [PMID: 34206477 PMCID: PMC8301835 DOI: 10.3390/biom11070924] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 06/16/2021] [Accepted: 06/18/2021] [Indexed: 11/24/2022] Open
Abstract
The coordination of bacterial genomic transcription involves an intricate network of interdependent genes encoding nucleoid-associated proteins (NAPs), DNA topoisomerases, RNA polymerase subunits and modulators of transcription machinery. The central element of this homeostatic regulatory system, integrating the information on cellular physiological state and producing a corresponding transcriptional response, is the multi-subunit RNA polymerase (RNAP) holoenzyme. In this review article, we argue that recent observations revealing DNA topoisomerases and metabolic enzymes associated with RNAP supramolecular complex support the notion of structural coupling between transcription machinery, DNA topology and cellular metabolism as a fundamental device coordinating the spatiotemporal genomic transcription. We analyse the impacts of various combinations of RNAP holoenzymes and global transcriptional regulators such as abundant NAPs, on genomic transcription from this viewpoint, monitoring the spatiotemporal patterns of couplons—overlapping subsets of the regulons of NAPs and RNAP sigma factors. We show that the temporal expression of regulons is by and large, correlated with that of cognate regulatory genes, whereas both the spatial organization and temporal expression of couplons is distinctly impacted by the regulons of NAPs and sigma factors. We propose that the coordination of the growth phase-dependent concentration gradients of global regulators with chromosome configurational dynamics determines the spatiotemporal patterns of genomic expression.
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Affiliation(s)
- Georgi Muskhelishvili
- School of Natural Sciences, Agricultural University of Georgia, David Aghmashenebeli Alley 24, Tbilisi 0159, Georgia
- Correspondence:
| | - Patrick Sobetzko
- Department of Chromosome Biology, Philipps-Universität Marburg, LOEWE-Zentrum für Synthetische Mikrobiologie, Hans-Meerwein-Straße, 35043 Marburg, Germany;
| | - Sanja Mehandziska
- School of Engineering and Science, Campus Ring 1, Jacobs University Bremen, 28759 Bremen, Germany;
| | - Andrew Travers
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK;
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK
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14
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Calise SJ, Chan EKL. Anti-rods/rings autoantibody and IMPDH filaments: an update after fifteen years of discovery. Autoimmun Rev 2020; 19:102643. [PMID: 32805424 DOI: 10.1016/j.autrev.2020.102643] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Accepted: 03/27/2020] [Indexed: 02/07/2023]
Abstract
Autoantibodies to unknown subcellular rod and ring-shaped structures were first discovered in sera from hepatitis C patients in 2005. Early studies showed a strong association between these anti-rods/rings antibodies (anti-RR) and the standard of care interferon-α plus ribavirin combination therapy (IFN/RBV), suggesting that anti-RR are drug-induced autoantibodies. In the context of hepatitis C, anti-RR have been linked with relapse from or lack of response to IFN/RBV in some patient cohorts. However, examples of anti-RR in other diseases and healthy individuals have also been reported over the years, although anti-RR remains a rare autoantibody response in general. The advent of new direct-acting antiviral drugs for chronic hepatitis C and studies of anti-RR from different parts of the world are also beginning to change the perception of anti-RR. The nucleotide biosynthetic enzyme inosine monophosphate dehydrogenase (IMPDH) has been identified as the major autoantigen recognized by anti-RR. Coincidentally, the assembly of IMPDH into micron-scale rod and ring-shaped structures was discovered around the same time as anti-RR. Knowledge of the fundamental biological properties and cellular functions of these structures, referred to as "IMPDH filaments" by cell biologists, has advanced in parallel to anti-RR antibodies. Recent studies have revealed that IMPDH filament assembly is a mechanism to prevent feedback inhibition of IMPDH and is therefore important for the increased nucleotide production required in hyperproliferating cells, like activated T cells. Fifteen years later, we review the history and current knowledge in both the anti-RR autoantibody and IMPDH filament fields. TAKE-HOME MESSAGE: Anti-rods/rings are recognized as an example of a drug-induced autoantibody in hepatitis C patients treated with interferon and ribavirin, although new studies suggest anti-rods/rings may be detected in other contexts and may depend on unknown environmental or genetic factors in different populations. Recent data suggest that the assembly of IMPDH into rod and ring structures, the targets of anti-rods/rings autoantibody, is a mechanism for hyperproliferating cells, like activated T cells, to maintain increased guanine nucleotide levels to support rapid cell division.
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Affiliation(s)
- S John Calise
- Department of Oral Biology, University of Florida, 1395 Center Drive, Gainesville, FL 32610-0424, USA.
| | - Edward K L Chan
- Department of Oral Biology, University of Florida, 1395 Center Drive, Gainesville, FL 32610-0424, USA.
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15
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Plana-Bonamaisó A, López-Begines S, Fernández-Justel D, Junza A, Soler-Tapia A, Andilla J, Loza-Alvarez P, Rosa JL, Miralles E, Casals I, Yanes O, de la Villa P, Buey RM, Méndez A. Post-translational regulation of retinal IMPDH1 in vivo to adjust GTP synthesis to illumination conditions. eLife 2020; 9:56418. [PMID: 32254022 PMCID: PMC7176436 DOI: 10.7554/elife.56418] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 03/30/2020] [Indexed: 02/06/2023] Open
Abstract
We report the in vivo regulation of Inosine-5´-monophosphate dehydrogenase 1 (IMPDH1) in the retina. IMPDH1 catalyzes the rate-limiting step in the de novo synthesis of guanine nucleotides, impacting the cellular pools of GMP, GDP and GTP. Guanine nucleotide homeostasis is central to photoreceptor cells, where cGMP is the signal transducing molecule in the light response. Mutations in IMPDH1 lead to inherited blindness. We unveil a light-dependent phosphorylation of retinal IMPDH1 at Thr159/Ser160 in the Bateman domain that desensitizes the enzyme to allosteric inhibition by GDP/GTP. When exposed to bright light, living mice increase the rate of GTP and ATP synthesis in their retinas; concomitant with IMPDH1 aggregate formation at the outer segment layer. Inhibiting IMPDH activity in living mice delays rod mass recovery. We unveil a novel mechanism of regulation of IMPDH1 in vivo, important for understanding GTP homeostasis in the retina and the pathogenesis of adRP10 IMPDH1 mutations.
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Affiliation(s)
- Anna Plana-Bonamaisó
- Department of Physiological Sciences, School of Medicine, Campus Universitari de Bellvitge, University of Barcelona, Barcelona, Spain.,Institut de Neurociències, Campus Universitari de Bellvitge, University of Barcelona, Barcelona, Spain
| | - Santiago López-Begines
- Department of Physiological Sciences, School of Medicine, Campus Universitari de Bellvitge, University of Barcelona, Barcelona, Spain
| | - David Fernández-Justel
- Metabolic Engineering Group, Department of Microbiology and Genetics. University of Salamanca, Salamanca, Spain
| | - Alexandra Junza
- CIBER of Diabetes and Associated Metabolic Diseases (CIBERDEM), Madrid, Spain.,Metabolomics Platform, IISPV, Department of Electronic Engineering, Universitat Rovira i Virgili, Tarragona, Spain
| | - Ariadna Soler-Tapia
- Department of Physiological Sciences, School of Medicine, Campus Universitari de Bellvitge, University of Barcelona, Barcelona, Spain
| | - Jordi Andilla
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Spain
| | - Pablo Loza-Alvarez
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Spain
| | - Jose Luis Rosa
- Department of Physiological Sciences, School of Medicine, Campus Universitari de Bellvitge, University of Barcelona, Barcelona, Spain.,Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Campus Universitari de Bellvitge, University of Barcelona, Barcelona, Spain
| | - Esther Miralles
- Centres Cientifics i Tecnològics (CCiTUB), University of Barcelona, Parc Científic de Barcelona, Barcelona, Spain
| | - Isidre Casals
- Centres Cientifics i Tecnològics (CCiTUB), University of Barcelona, Parc Científic de Barcelona, Barcelona, Spain
| | - Oscar Yanes
- CIBER of Diabetes and Associated Metabolic Diseases (CIBERDEM), Madrid, Spain.,Metabolomics Platform, IISPV, Department of Electronic Engineering, Universitat Rovira i Virgili, Tarragona, Spain
| | - Pedro de la Villa
- Physiology Unit, Dept of Systems Biology, School of Medicine, University of Alcalá, Madrid, Spain.,Visual Neurophysiology Group-IRYCIS, Madrid, Spain
| | - Ruben M Buey
- Metabolic Engineering Group, Department of Microbiology and Genetics. University of Salamanca, Salamanca, Spain
| | - Ana Méndez
- Department of Physiological Sciences, School of Medicine, Campus Universitari de Bellvitge, University of Barcelona, Barcelona, Spain.,Institut de Neurociències, Campus Universitari de Bellvitge, University of Barcelona, Barcelona, Spain.,Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Campus Universitari de Bellvitge, University of Barcelona, Barcelona, Spain
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16
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The functional impact of the C/N-terminal extensions of the mouse retinal IMPDH1 isoforms: a kinetic evaluation. Mol Cell Biochem 2019; 465:155-164. [PMID: 31838626 DOI: 10.1007/s11010-019-03675-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 12/07/2019] [Indexed: 10/25/2022]
Abstract
Mutations in the retinal inosine monophosphate dehydrogenase1 (IMPDH1) gene is believed to be one cause of retinitis pigmentosa (RP). The main structural difference between the mutation-susceptible retinal isoforms with canonical one resides in the C- and N-terminal extensions. There are limited studies on the structure and function of terminal peptide extensions of the IMPDH1 retinal isoforms. Using recombinant murine IMPDH1 (mH1), we evaluated the kinetics of the retinal isoforms along with inhibition by some of the purine nucleotides. Molecular modeling tools were also applied to study the probable effect(s) of the terminal peptide tails on the function of the retinal isoforms. Molecular dynamic simulations indicated the possible impact of the end-terminal segments on the enzyme function through interactions with the enzyme's finger domain, affecting its critical pseudo barrel structure. The higher experimentally-determined Km and Ki values of the retinal mIMPDH1 (546) and mIMPDH1 (603) relative to that of the canonical isoform, mIMPDH1 (514), might clearly be due to these interactions. Furthermore and despite of the canonical isoform, the retinal isoforms of mH1 exhibited no NAD+ substrate inhibition. The resent data would certainly provide the ground for future evaluation of the physiological significance of these variations.
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17
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Camici M, Garcia-Gil M, Pesi R, Allegrini S, Tozzi MG. Purine-Metabolising Enzymes and Apoptosis in Cancer. Cancers (Basel) 2019; 11:cancers11091354. [PMID: 31547393 PMCID: PMC6769685 DOI: 10.3390/cancers11091354] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 09/03/2019] [Accepted: 09/07/2019] [Indexed: 12/17/2022] Open
Abstract
The enzymes of both de novo and salvage pathways for purine nucleotide synthesis are regulated to meet the demand of nucleic acid precursors during proliferation. Among them, the salvage pathway enzymes seem to play the key role in replenishing the purine pool in dividing and tumour cells that require a greater amount of nucleotides. An imbalance in the purine pools is fundamental not only for preventing cell proliferation, but also, in many cases, to promote apoptosis. It is known that tumour cells harbour several mutations that might lead to defective apoptosis-inducing pathways, and this is probably at the basis of the initial expansion of the population of neoplastic cells. Therefore, knowledge of the molecular mechanisms that lead to apoptosis of tumoural cells is key to predicting the possible success of a drug treatment and planning more effective and focused therapies. In this review, we describe how the modulation of enzymes involved in purine metabolism in tumour cells may affect the apoptotic programme. The enzymes discussed are: ectosolic and cytosolic 5'-nucleotidases, purine nucleoside phosphorylase, adenosine deaminase, hypoxanthine-guanine phosphoribosyltransferase, and inosine-5'-monophosphate dehydrogenase, as well as recently described enzymes particularly expressed in tumour cells, such as deoxynucleoside triphosphate triphosphohydrolase and 7,8-dihydro-8-oxoguanine triphosphatase.
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Affiliation(s)
- Marcella Camici
- Dipartimento di Biologia, Unità di Biochimica, Via S. Zeno 51, 56127 Pisa, Italy.
| | - Mercedes Garcia-Gil
- Dipartimento di Biologia, Unità di Fisiologia Generale, Via S. Zeno 31, 56127 Pisa, Italy
| | - Rossana Pesi
- Dipartimento di Biologia, Unità di Biochimica, Via S. Zeno 51, 56127 Pisa, Italy
| | - Simone Allegrini
- Dipartimento di Biologia, Unità di Biochimica, Via S. Zeno 51, 56127 Pisa, Italy
| | - Maria Grazia Tozzi
- Dipartimento di Biologia, Unità di Biochimica, Via S. Zeno 51, 56127 Pisa, Italy
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18
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Genome Editing as a Treatment for the Most Prevalent Causative Genes of Autosomal Dominant Retinitis Pigmentosa. Int J Mol Sci 2019; 20:ijms20102542. [PMID: 31126147 PMCID: PMC6567127 DOI: 10.3390/ijms20102542] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 05/15/2019] [Accepted: 05/22/2019] [Indexed: 02/07/2023] Open
Abstract
: Inherited retinal dystrophies (IRDs) are a clinically and genetically heterogeneous group of diseases with more than 250 causative genes. The most common form is retinitis pigmentosa. IRDs lead to vision impairment for which there is no universal cure. Encouragingly, a first gene supplementation therapy has been approved for an autosomal recessive IRD. However, for autosomal dominant IRDs, gene supplementation therapy is not always pertinent because haploinsufficiency is not the only cause. Disease-causing mechanisms are often gain-of-function or dominant-negative, which usually require alternative therapeutic approaches. In such cases, genome-editing technology has raised hopes for treatment. Genome editing could be used to i) invalidate both alleles, followed by supplementation of the wild type gene, ii) specifically invalidate the mutant allele, with or without gene supplementation, or iii) to correct the mutant allele. We review here the most prevalent genes causing autosomal dominant retinitis pigmentosa and the most appropriate genome-editing strategy that could be used to target their different causative mutations.
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19
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Chacko S, Boshoff HIM, Singh V, Ferraris DM, Gollapalli DR, Zhang M, Lawson AP, Pepi MJ, Joachimiak A, Rizzi M, Mizrahi V, Cuny GD, Hedstrom L. Expanding Benzoxazole-Based Inosine 5'-Monophosphate Dehydrogenase (IMPDH) Inhibitor Structure-Activity As Potential Antituberculosis Agents. J Med Chem 2018; 61:4739-4756. [PMID: 29746130 DOI: 10.1021/acs.jmedchem.7b01839] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
New drugs and molecular targets are urgently needed to address the emergence and spread of drug-resistant tuberculosis. Mycobacterium tuberculosis ( Mtb) inosine 5'-monophosphate dehydrogenase 2 ( MtbIMPDH2) is a promising yet controversial potential target. The inhibition of MtbIMPDH2 blocks the biosynthesis of guanine nucleotides, but high concentrations of guanine can potentially rescue the bacteria. Herein we describe an expansion of the structure-activity relationship (SAR) for the benzoxazole series of MtbIMPDH2 inhibitors and demonstrate that minimum inhibitory concentrations (MIC) of ≤1 μM can be achieved. The antibacterial activity of the most promising compound, 17b (Q151), is derived from the inhibition of MtbIMPDH2 as demonstrated by conditional knockdown and resistant strains. Importantly, guanine does not change the MIC of 17b, alleviating the concern that guanine salvage can protect Mtb in vivo. These findings suggest that MtbIMPDH2 is a vulnerable target for tuberculosis.
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Affiliation(s)
| | - Helena I M Boshoff
- Tuberculosis Research Section , National Institute of Allergy and Infectious Diseases , Bethesda , Maryland 20892 , United States
| | - Vinayak Singh
- Department of Drug Discovery and Development & Institute of Infectious Disease and Molecular Medicine , H3D Drug Discovery and Development Centre, University of Cape Town , Rondebosch , Cape Town 7701 , South Africa
| | - Davide M Ferraris
- Dipartimento di Scienze del Farmaco , Universitá del Piemonte Orientale , Via Bovio 6 , 28100 Novara , Italy
| | | | | | | | | | - Andrzej Joachimiak
- Center for Structural Genomics of Infectious Diseases and Department of Biochemistry and Molecular Biology , University of Chicago , Chicago , Illinois 60557 , United States.,Structural Biology Center, Biosciences , Argonne National Laboratory , 9700 S. Cass Avenue, Argonne , Illinois 60439 , United States
| | - Menico Rizzi
- Dipartimento di Scienze del Farmaco , Universitá del Piemonte Orientale , Via Bovio 6 , 28100 Novara , Italy
| | - Valerie Mizrahi
- MRC/NHLS/UCT Molecular Mycobacteriology Research Unit & DST/NRF Centre of Excellence for Biomedical TB Research, Institute of Infectious Disease and Molecular Medicine & Department of Pathology , University of Cape Town , Anzio Road , Observatory 7925 , South Africa
| | - Gregory D Cuny
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy , University of Houston , Health Building 2, 4849 Calhoun Road , Houston , Texas 77204 , United States
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20
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Pua KH, Stiles DT, Sowa ME, Verdine GL. IMPDH2 Is an Intracellular Target of the Cyclophilin A and Sanglifehrin A Complex. Cell Rep 2017; 18:432-442. [PMID: 28076787 DOI: 10.1016/j.celrep.2016.12.030] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 11/21/2016] [Accepted: 12/10/2016] [Indexed: 11/16/2022] Open
Abstract
Natural products have demonstrated utility in the clinic and can also act as probes to understand complex cellular pathways. Sanglifehrin A (SFA) is a mixed polyketide and non-ribosomal peptide synthase natural product with sub-nano-molar affinity for its receptor cyclophilin A (PPIA). It has been shown to behave in vitro as an immune suppressant. Here, we identify inosine-5'-monophosphate dehydrogenase 2 (IMPDH2) as an intracellular target of the PPIA-SFA binary complex. The formation of this ternary complex does not inhibit the enzymatic activity of IMPDH2. Rather, ternary complex formation modulates cell growth through interaction with the cystathionine-β-synthase (CBS) domain of IMPDH2. We further demonstrate that the SFA complex is highly isoform selective for IMPDH2 (versus IMPDH1). This work reveals a role for the CBS domains of IMPDH2 in cellular proliferation, suggesting a more complex role than previously suspected for IMPDH2 in T cell activation and proliferation.
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Affiliation(s)
- Khian Hong Pua
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA; Warp Drive Bio, Cambridge, MA 02139, USA
| | - Dylan T Stiles
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA; Warp Drive Bio, Cambridge, MA 02139, USA
| | - Mathew E Sowa
- Warp Drive Bio, Cambridge, MA 02139, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Gregory L Verdine
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA; Warp Drive Bio, Cambridge, MA 02139, USA; Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA.
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21
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Genetic characterization and disease mechanism of retinitis pigmentosa; current scenario. 3 Biotech 2017; 7:251. [PMID: 28721681 DOI: 10.1007/s13205-017-0878-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 07/10/2017] [Indexed: 12/21/2022] Open
Abstract
Retinitis pigmentosa is a group of genetically transmitted disorders affecting 1 in 3000-8000 individual people worldwide ultimately affecting the quality of life. Retinitis pigmentosa is characterized as a heterogeneous genetic disorder which leads by progressive devolution of the retina leading to a progressive visual loss. It can occur in syndromic (with Usher syndrome and Bardet-Biedl syndrome) as well as non-syndromic nature. The mode of inheritance can be X-linked, autosomal dominant or autosomal recessive manner. To date 58 genes have been reported to associate with retinitis pigmentosa most of them are either expressed in photoreceptors or the retinal pigment epithelium. This review focuses on the disease mechanisms and genetics of retinitis pigmentosa. As retinitis pigmentosa is tremendously heterogeneous disorder expressing a multiplicity of mutations; different variations in the same gene might induce different disorders. In recent years, latest technologies including whole-exome sequencing contributing effectively to uncover the hidden genesis of retinitis pigmentosa by reporting new genetic mutations. In future, these advancements will help in better understanding the genotype-phenotype correlations of disease and likely to develop new therapies.
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22
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Yamada T, Krzeminski M, Bozoky Z, Forman-Kay JD, Strange K. Role of CBS and Bateman Domains in Phosphorylation-Dependent Regulation of a CLC Anion Channel. Biophys J 2017; 111:1876-1886. [PMID: 27806269 DOI: 10.1016/j.bpj.2016.09.036] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 08/30/2016] [Accepted: 09/23/2016] [Indexed: 12/13/2022] Open
Abstract
Eukaryotic CLC anion channels and transporters are homodimeric proteins composed of multiple α-helical membrane domains and large cytoplasmic C-termini containing two cystathionine-β-synthase domains (CBS1 and CBS2) that dimerize to form a Bateman domain. The Bateman domains of adjacent CLC subunits interact to form a Bateman domain dimer. The functions of CLC CBS and Bateman domains are poorly understood. We utilized the Caenorhabditis elegans CLC-1/2/Ka/Kb anion channel homolog CLH-3b to characterize the regulatory roles of CLC cytoplasmic domains. CLH-3b activity is reduced by phosphorylation or deletion of a 14-amino-acid activation domain (AD) located on the linker connecting CBS1 and CBS2. We demonstrate here that phosphorylation-dependent reductions in channel activity require an intact Bateman domain dimer and concomitant phosphorylation or deletion of both ADs. Regulation of a CLH-3b AD deletion mutant is reconstituted by intracellular perfusion with recombinant 14-amino-acid AD peptides. The sulfhydryl reactive reagent 2-(trimethylammonium)ethyl methanethiosulfonate bromide (MTSET) alters in a phosphorylation-dependent manner the activity of channels containing single cysteine residues that are engineered into the short intracellular loop connecting membrane α-helices H and I (H-I loop), the AD, CBS1, and CBS2. In contrast, MTSET has no effect on channels in which cysteine residues are engineered into intracellular regions that are dispensable for regulation. These studies together with our previous work suggest that binding and unbinding of the AD to the Bateman domain dimer induces conformational changes that are transduced to channel membrane domains via the H-I loop. Our findings provide new, to our knowledge, insights into the roles of CLC Bateman domains and the structure-function relationships that govern the regulation of CLC protein activity by diverse ligands and signaling pathways.
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Affiliation(s)
- Toshiki Yamada
- MDI Biological Laboratory, Kathryn W. Davis Center for Regenerative Biology and Medicine, Salisbury Cove, Maine
| | - Mickael Krzeminski
- Department of Molecular Structure and Function, Hospital for Sick Kids, Toronto, Ontario
| | - Zoltan Bozoky
- Department of Molecular Structure and Function, Hospital for Sick Kids, Toronto, Ontario
| | - Julie D Forman-Kay
- Department of Molecular Structure and Function, Hospital for Sick Kids, Toronto, Ontario
| | - Kevin Strange
- MDI Biological Laboratory, Kathryn W. Davis Center for Regenerative Biology and Medicine, Salisbury Cove, Maine.
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23
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Abstract
In this review, van der Knapp and Verrijzer discuss the current understanding of the molecular mechanisms connecting metabolism to gene expression and their implications for development and disease. To make the appropriate developmental decisions or maintain homeostasis, cells and organisms must coordinate the expression of their genome and metabolic state. However, the molecular mechanisms that relay environmental cues such as nutrient availability to the appropriate gene expression response remain poorly understood. There is a growing awareness that central components of intermediary metabolism are cofactors or cosubstrates of chromatin-modifying enzymes. As such, their concentrations constitute a potential regulatory interface between the metabolic and chromatin states. In addition, there is increasing evidence for a direct involvement of classic metabolic enzymes in gene expression control. These dual-function proteins may provide a direct link between metabolic programing and the control of gene expression. Here, we discuss our current understanding of the molecular mechanisms connecting metabolism to gene expression and their implications for development and disease.
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Affiliation(s)
- Jan A van der Knaap
- Department of Biochemistry, Erasmus University Medical Center, 3000 DR Rotterdam, the Netherlands
| | - C Peter Verrijzer
- Department of Biochemistry, Erasmus University Medical Center, 3000 DR Rotterdam, the Netherlands
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24
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Govindaraj V, Krishnagiri H, Chauhan MS, Rao AJ. BRCA-1 Gene Expression and Comparative Proteomic Profile of Primordial Follicles from Young and Adult Buffalo (Bubalus bubalis) Ovaries. Anim Biotechnol 2016; 28:94-103. [DOI: 10.1080/10495398.2016.1210613] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
| | | | - Manmohan Singh Chauhan
- Embryo Biotechnology Lab, Animal Biotechnology Centre, ICAR-National Dairy Research Institute, Karnal, India
| | - A. J. Rao
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
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25
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Tokuda K, Kuramitsu Y, Baron B, Kitagawa T, Tokuda N, Kobayashi M, Kimura K, Sonoda KH, Nakamura K. Changes in metabolic proteins in ex vivo rat retina during glutamate-induced neural progenitor cell induction. Mol Cell Biochem 2016; 419:177-84. [PMID: 27421851 DOI: 10.1007/s11010-016-2769-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 07/09/2016] [Indexed: 12/11/2022]
Abstract
Understanding how energy metabolism and related proteins influence neural progenitor cells in adult tissues is critical for developing new strategies in clinical tissue regeneration therapy. We have recently reported that a subtoxic concentration of glutamate-induced neural progenitor cells in the mature ex vivo rat retina. We herein explore changes in the metabolic pathways during the process. We firstly observed an increase in lactate and lactate dehydrogenase concentration in the glutamate-treated retina. We then investigated the levels of glycolytic enzymes and confirmed significant upregulation of pyruvate kinase M type (PKM), especially PKM2, enolase, phosphoglycerate mutase 1 (PGAM1), and inosine-5'-monophosphate dehydrogenase (IMPDH1) in the glutamate-treated retina compared to the untreated retina. An analysis of the subcellular localization of PKM2 revealed nuclear translocation in the treated retina, which has been reported to regulate cell cycle proliferation and glycolytic enzymes. Our findings indicate that the mature rat retina undergoes an increase in aerobic glycolysis. PKM2, both in the cytoplasm and in the nucleus, may thus play an important role during neural progenitor cell induction, as it does in other proliferating cells.
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Affiliation(s)
- Kazuhiro Tokuda
- Department of Ophthalmology, Yamaguchi University Graduate School of Medicine, Ube, Yamaguchi, 755-8505, Japan.,Department of Biochemistry and Functional Proteomics, Yamaguchi University Graduate School of Medicine, Ube, Yamaguchi, 755-8505, Japan
| | - Yasuhiro Kuramitsu
- Department of Biochemistry and Functional Proteomics, Yamaguchi University Graduate School of Medicine, Ube, Yamaguchi, 755-8505, Japan.
| | - Byron Baron
- Department of Biochemistry and Functional Proteomics, Yamaguchi University Graduate School of Medicine, Ube, Yamaguchi, 755-8505, Japan.,Centre for Molecular Medicine and Biobanking, Faculty of Medicine and Surgery, University of Malta, Msida, MSD2080, Malta
| | - Takao Kitagawa
- Department of Biochemistry and Functional Proteomics, Yamaguchi University Graduate School of Medicine, Ube, Yamaguchi, 755-8505, Japan
| | - Nobuko Tokuda
- Faculty of Health Sciences, Yamaguchi University Graduate School of Medicine, Ube, 755-8505, Japan
| | - Masaaki Kobayashi
- Department of Ophthalmology, Yamaguchi University Graduate School of Medicine, Ube, Yamaguchi, 755-8505, Japan
| | - Kazuhiro Kimura
- Department of Ophthalmology, Yamaguchi University Graduate School of Medicine, Ube, Yamaguchi, 755-8505, Japan
| | - Koh-Hei Sonoda
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-Ku, Fukuoka, 812-8582, Japan
| | - Kazuyuki Nakamura
- Department of Biochemistry and Functional Proteomics, Yamaguchi University Graduate School of Medicine, Ube, Yamaguchi, 755-8505, Japan
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Sullivan LS, Koboldt DC, Bowne SJ, Lang S, Blanton SH, Cadena E, Avery CE, Lewis RA, Webb-Jones K, Wheaton DH, Birch DG, Coussa R, Ren H, Lopez I, Chakarova C, Koenekoop RK, Garcia CA, Fulton RS, Wilson RK, Weinstock GM, Daiger SP. A dominant mutation in hexokinase 1 (HK1) causes retinitis pigmentosa. Invest Ophthalmol Vis Sci 2014; 55:7147-58. [PMID: 25190649 DOI: 10.1167/iovs.14-15419] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To identify the cause of retinitis pigmentosa (RP) in UTAD003, a large, six-generation Louisiana family with autosomal dominant retinitis pigmentosa (adRP). METHODS A series of strategies, including candidate gene screening, linkage exclusion, genome-wide linkage mapping, and whole-exome next-generation sequencing, was used to identify a mutation in a novel disease gene on chromosome 10q22.1. Probands from an additional 404 retinal degeneration families were subsequently screened for mutations in this gene. RESULTS Exome sequencing in UTAD003 led to identification of a single, novel coding variant (c.2539G>A, p.Glu847Lys) in hexokinase 1 (HK1) present in all affected individuals and absent from normal controls. One affected family member carries two copies of the mutation and has an unusually severe form of disease, consistent with homozygosity for this mutation. Screening of additional adRP probands identified four other families (American, Canadian, and Sicilian) with the same mutation and a similar range of phenotypes. The families share a rare 450-kilobase haplotype containing the mutation, suggesting a founder mutation among otherwise unrelated families. CONCLUSIONS We identified an HK1 mutation in five adRP families. Hexokinase 1 catalyzes phosphorylation of glucose to glucose-6-phosphate. HK1 is expressed in retina, with two abundant isoforms expressed at similar levels. The Glu847Lys mutation is located at a highly conserved position in the protein, outside the catalytic domains. We hypothesize that the effect of this mutation is limited to the retina, as no systemic abnormalities in glycolysis were detected. Prevalence of the HK1 mutation in our cohort of RP families is 1%.
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Affiliation(s)
- Lori S Sullivan
- Human Genetics Center, University of Texas Health Science Center, Houston, Texas, United States
| | - Daniel C Koboldt
- The Genome Institute at Washington University, St. Louis, Missouri, United States
| | - Sara J Bowne
- Human Genetics Center, University of Texas Health Science Center, Houston, Texas, United States
| | - Steven Lang
- John P. Hussman Institute for Human Genomics, University of Miami, Miami, Florida, United States
| | - Susan H Blanton
- John P. Hussman Institute for Human Genomics, University of Miami, Miami, Florida, United States
| | - Elizabeth Cadena
- Human Genetics Center, University of Texas Health Science Center, Houston, Texas, United States
| | - Cheryl E Avery
- Human Genetics Center, University of Texas Health Science Center, Houston, Texas, United States
| | - Richard A Lewis
- Departments of Ophthalmology, Medicine, Pediatrics, and Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States
| | - Kaylie Webb-Jones
- The Retina Foundation of the Southwest, Dallas, Texas, United States
| | - Dianna H Wheaton
- The Retina Foundation of the Southwest, Dallas, Texas, United States
| | - David G Birch
- The Retina Foundation of the Southwest, Dallas, Texas, United States
| | - Razck Coussa
- McGill Ocular Genetics Laboratory, Departments of Paediatric Surgery, Human Genetics, and Ophthalmology, McGill University Health Center, Montreal, Quebec, Canada
| | - Huanan Ren
- McGill Ocular Genetics Laboratory, Departments of Paediatric Surgery, Human Genetics, and Ophthalmology, McGill University Health Center, Montreal, Quebec, Canada
| | - Irma Lopez
- McGill Ocular Genetics Laboratory, Departments of Paediatric Surgery, Human Genetics, and Ophthalmology, McGill University Health Center, Montreal, Quebec, Canada
| | - Christina Chakarova
- Institute of Ophthalmology, University College London, London, United Kingdom
| | - Robert K Koenekoop
- McGill Ocular Genetics Laboratory, Departments of Paediatric Surgery, Human Genetics, and Ophthalmology, McGill University Health Center, Montreal, Quebec, Canada
| | - Charles A Garcia
- Department of Ophthalmology and Visual Sciences, University of Texas Health Science Center, Houston, Texas, United States
| | - Robert S Fulton
- The Genome Institute at Washington University, St. Louis, Missouri, United States
| | - Richard K Wilson
- The Genome Institute at Washington University, St. Louis, Missouri, United States
| | - George M Weinstock
- The Genome Institute at Washington University, St. Louis, Missouri, United States
| | - Stephen P Daiger
- Human Genetics Center, University of Texas Health Science Center, Houston, Texas, United States Department of Ophthalmology and Visual Sciences, University of Texas Health Science Center, Houston, Texas, United States
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Georgieva D, Dimitrov R, Kitanova M, Genova G. New X-chromosomal interactors of dFMRP regulate axonal and synaptic morphology of brain neurons in Drosophila melanogaster. BIOTECHNOL BIOTEC EQ 2014; 28:697-709. [PMID: 26740770 PMCID: PMC4684054 DOI: 10.1080/13102818.2014.937897] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 05/21/2014] [Indexed: 11/12/2022] Open
Abstract
Fragile X syndrome is a neuro-developmental disease caused by transcriptional inactivation of the gene FMR1 (fragile X mental retardation 1) and loss of its protein product FMRP. FMRP has multiple neuronal functions which are implemented together with other proteins. To better understand these functions, the aim of this study was to reveal new protein interactors of dFMRP. In a forward genetic screen, we isolated ethyl-metanesulphonate-induced X-chromosomal modifier mutations of dfmr1. Four of them were identified and belong to the genes: peb/hindsight, rok, shaggy and ras. They are dominant suppressors of the dfmr1 overexpression wing phenotype ‘notched wings’. These mutations dominantly affected the axonal and synaptic morphology of the lateral ventral neurons (LNv's) in adult Drosophila brains. Heterozygotes for each of them displayed effects in the axonal growth, pathfinding, branching and in the synapse formation of these neurons. Double heterozygotes for both dfmr1-null mutation and for each of the suppressor mutations showed robust genetic interactions in the fly central nervous system. The mutations displayed severe defects in the axonal growth and synapse formation of the LNv's in adult brains. Our biochemical studies showed that neither of the proteins – Rok, Shaggy, Peb/Hnt or Ras – encoded by the four mutated genes regulates the protein level of dFMRP, but dFMRP negatively regulates the protein expression level of Rok in the brain. Altogether, these data suggest that Rok, Shaggy, Peb/Hnt and Ras are functional partners of dFMRP, which are required for correct wing development and for neuronal connectivity in Drosophila brain.
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Affiliation(s)
- Dimitrina Georgieva
- Faculty of Biology, Sofia University 'St. Kliment Ohridski' , Sofia , Bulgaria
| | - Roumen Dimitrov
- Institute of Biology and Immunology of Reproduction, Bulgarian Academy of Sciences , Sofia , Bulgaria
| | - Meglena Kitanova
- Faculty of Biology, Sofia University 'St. Kliment Ohridski' , Sofia , Bulgaria
| | - Ginka Genova
- Faculty of Biology, Sofia University 'St. Kliment Ohridski' , Sofia , Bulgaria
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28
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Panigrahi R, Hazari S, Chandra S, Chandra PK, Datta S, Kurt R, Cameron CE, Huang Z, Zhang H, Garry RF, Balart LA, Dash S. Interferon and ribavirin combination treatment synergistically inhibit HCV internal ribosome entry site mediated translation at the level of polyribosome formation. PLoS One 2013; 8:e72791. [PMID: 24009705 PMCID: PMC3751885 DOI: 10.1371/journal.pone.0072791] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 07/12/2013] [Indexed: 12/20/2022] Open
Abstract
PURPOSE Although chronic hepatitis C virus (HCV) infection has been treated with the combination of interferon alpha (IFN-α) and ribavirin (RBV) for over a decade, the mechanism of antiviral synergy is not well understood. We aimed to determine the synergistic antiviral mechanisms of IFN-α and RBV combination treatment using HCV cell culture. METHODS The antiviral efficacy of IFN-α, RBV alone and in combination was quantitatively measured using HCV infected and replicon cell culture. Direct antiviral activity of these two drugs at the level of HCV internal ribosome entry site (IRES) mediated translation in Huh-7 cell culture was investigated. The synergistic antiviral effect of IFN-α and RBV combination treatment was verified using both the CalcuSyn Software and MacSynergy Software. RESULTS RBV combination with IFN-α efficiently inhibits HCV replication cell culture. Our results demonstrate that IFN-α, interferon lambda (IFN-λ) and RBV each inhibit the expression of HCV IRES-GFP and that they have a minimal effect on the expression of GFP in which the translation is not IRES dependent. The combination treatments of RBV along with IFN-α or IFN-λ were highly synergistic with combination indexes <1. We show that IFN-α treatment induce levels of PKR and eIF2α phosphorylation that prevented ribosome loading of the HCV IRES-GFP mRNA. Silencing of PKR expression in Huh-7 cells prevented the inhibitory effect of IFN-α on HCV IRES-GFP expression. RBV also blocked polyribosome loading of HCV-IRES mRNA through the inhibition of cellular IMPDH activity, and induced PKR and eIF2α phosphorylation. Knockdown of PKR or IMPDH prevented RBV induced HCV IRES-GFP translation. CONCLUSIONS We demonstrated both IFN-α and RBV inhibit HCV IRES through prevention of polyribosome formation. The combination of IFN-α and RBV treatment synergistically inhibits HCV IRES translation via using two different mechanisms involving PKR activation and depletion of intracellular guanosine pool through inhibition of IMPDH.
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Affiliation(s)
- Rajesh Panigrahi
- Pathology and Laboratory Medicine, Tulane University School of Medicine, New Orleans, Louisiana, United States of America
| | - Sidhartha Hazari
- Pathology and Laboratory Medicine, Tulane University School of Medicine, New Orleans, Louisiana, United States of America
| | - Sruti Chandra
- Pathology and Laboratory Medicine, Tulane University School of Medicine, New Orleans, Louisiana, United States of America
| | - Partha K. Chandra
- Pathology and Laboratory Medicine, Tulane University School of Medicine, New Orleans, Louisiana, United States of America
| | - Sibnarayan Datta
- Pathology and Laboratory Medicine, Tulane University School of Medicine, New Orleans, Louisiana, United States of America
| | - Ramazan Kurt
- Pathology and Laboratory Medicine, Tulane University School of Medicine, New Orleans, Louisiana, United States of America
| | - Craig E. Cameron
- Department of Biochemistry and Molecular Biology, Penn State University, University Park, United States of America
| | - Zhuhui Huang
- Hepatitis Research Program, Southern Research Institute, Frederick, Maryland, United States of America
| | - Haitao Zhang
- Pathology and Laboratory Medicine, Tulane University School of Medicine, New Orleans, Louisiana, United States of America
| | - Robert F. Garry
- Micribiology and Immunology, Tulane University School of Medicine, New Orleans, Louisiana, United States of America
| | - Luis A. Balart
- Gastroenterology, Hepatology and Medicine, Tulane University School of Medicine, New Orleans, Louisiana, United States of America
| | - Srikanta Dash
- Pathology and Laboratory Medicine, Tulane University School of Medicine, New Orleans, Louisiana, United States of America
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29
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Thomas EC, Gunter JH, Webster JA, Schieber NL, Oorschot V, Parton RG, Whitehead JP. Different characteristics and nucleotide binding properties of inosine monophosphate dehydrogenase (IMPDH) isoforms. PLoS One 2012; 7:e51096. [PMID: 23236438 PMCID: PMC3517587 DOI: 10.1371/journal.pone.0051096] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Accepted: 10/29/2012] [Indexed: 11/18/2022] Open
Abstract
We recently reported that Inosine Monophosphate Dehydrogenase (IMPDH), a rate-limiting enzyme in de novo guanine nucleotide biosynthesis, clustered into macrostructures in response to decreased nucleotide levels and that there were differences between the IMPDH isoforms, IMPDH1 and IMPDH2. We hypothesised that the Bateman domains, which are present in both isoforms and serve as energy-sensing/allosteric modules in unrelated proteins, would contribute to isoform-specific differences and that mutations situated in and around this domain in IMPDH1 which give rise to retinitis pigmentosa (RP) would compromise regulation. We employed immuno-electron microscopy to investigate the ultrastructure of IMPDH macrostructures and live-cell imaging to follow clustering of an IMPDH2-GFP chimera in real-time. Using a series of IMPDH1/IMPDH2 chimera we demonstrated that the propensity to cluster was conferred by the N-terminal 244 amino acids, which includes the Bateman domain. A protease protection assay suggested isoform-specific purine nucleotide binding characteristics, with ATP protecting IMPDH1 and AMP protecting IMPDH2, via a mechanism involving conformational changes upon nucleotide binding to the Bateman domain without affecting IMPDH catalytic activity. ATP binding to IMPDH1 was confirmed in a nucleotide binding assay. The RP-causing mutation, R224P, abolished ATP binding and nucleotide protection and this correlated with an altered propensity to cluster. Collectively these data demonstrate that (i) the isoforms are differentially regulated by AMP and ATP by a mechanism involving the Bateman domain, (ii) communication occurs between the Bateman and catalytic domains and (iii) the RP-causing mutations compromise such regulation. These findings support the idea that the IMPDH isoforms are subject to distinct regulation and that regulatory defects contribute to human disease.
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Affiliation(s)
- Elaine C. Thomas
- Diamantina Institute for Cancer, Immunology and Metabolic Medicine, Princess Alexandra Hospital, University of Queensland, Brisbane, Queensland, Australia
- * E-mail: (ECT); (JPW)
| | - Jennifer H. Gunter
- Diamantina Institute for Cancer, Immunology and Metabolic Medicine, Princess Alexandra Hospital, University of Queensland, Brisbane, Queensland, Australia
| | - Julie A. Webster
- Diamantina Institute for Cancer, Immunology and Metabolic Medicine, Princess Alexandra Hospital, University of Queensland, Brisbane, Queensland, Australia
- Metabolic Medicine, Mater Medical Research Institute, South Brisbane, Queensland, Australia
| | - Nicole L. Schieber
- The University of Queensland, Institute for Molecular Bioscience, Brisbane, Queensland, Australia
| | - Viola Oorschot
- The University of Queensland, Institute for Molecular Bioscience, Brisbane, Queensland, Australia
| | - Robert G. Parton
- The University of Queensland, Institute for Molecular Bioscience, Brisbane, Queensland, Australia
| | - Jonathan P. Whitehead
- Diamantina Institute for Cancer, Immunology and Metabolic Medicine, Princess Alexandra Hospital, University of Queensland, Brisbane, Queensland, Australia
- Metabolic Medicine, Mater Medical Research Institute, South Brisbane, Queensland, Australia
- * E-mail: (ECT); (JPW)
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30
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Kozhevnikova EN, van der Knaap JA, Pindyurin AV, Ozgur Z, van Ijcken WFJ, Moshkin YM, Verrijzer CP. Metabolic enzyme IMPDH is also a transcription factor regulated by cellular state. Mol Cell 2012; 47:133-9. [PMID: 22658723 DOI: 10.1016/j.molcel.2012.04.030] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Revised: 03/13/2012] [Accepted: 04/26/2012] [Indexed: 01/27/2023]
Abstract
Cells need to coordinate gene expression and metabolic state. Inosine monophosphate dehydrogenase (IMPDH) controls the guanine nucleotide pool and, thereby, cell proliferation. We found that Drosophila IMPDH is also a DNA-binding transcriptional repressor. IMPDH attenuates expression of histone genes and E2f, a key driver of cell proliferation. Nuclear IMPDH accumulates during the G2 phase of the cell cycle or following replicative or oxidative stress. Thus, IMPDH can couple the expression of histones and E2F to cellular state. Genome-wide profiling and in vitro binding assays established that IMPDH binds sequence specifically to single-stranded, CT-rich DNA elements. Surprisingly, this DNA-binding function is conserved in E. coli IMPDH. The catalytic function of IMPDH is not required for DNA binding. Yet substitutions that correspond to human retinitis pigmentosa mutations disrupt IMPDH binding to CT-rich, single-stranded DNA elements. By doubling as nucleotide biosynthetic enzyme or transcription factor, IMPDH can either enable or restrict cell proliferation.
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Affiliation(s)
- Elena N Kozhevnikova
- Department of Biochemistry and Center for Biomedical Genetics, Erasmus University Medical Centre, P.O. Box 1738, 3000 DR, Rotterdam, The Netherlands
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31
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Sharma YV, Cojocaru RI, Ritter LM, Khattree N, Brooks M, Scott A, Swaroop A, Goldberg AFX. Protective gene expression changes elicited by an inherited defect in photoreceptor structure. PLoS One 2012; 7:e31371. [PMID: 22363631 PMCID: PMC3282697 DOI: 10.1371/journal.pone.0031371] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Accepted: 01/09/2012] [Indexed: 11/19/2022] Open
Abstract
Inherited defects in retinal photoreceptor structure impair visual transduction, disrupt relationship with the retinal pigment epithelium (RPE), and compromise cell viability. A variety of progressive retinal degenerative diseases can result, and knowledge of disease etiology remains incomplete. To investigate pathogenic mechanisms in such instances, we have characterized rod photoreceptor and retinal gene expression changes in response to a defined insult to photoreceptor structure, using the retinal degeneration slow (rds) mouse model. Global gene expression profiling was performed on flow-sorted rds and wild-type rod photoreceptors immediately prior and subsequent to times at which OSs are normally elaborated. Dysregulated genes were identified via microarray hybridization, and selected candidates were validated using quantitative PCR analyses. Both the array and qPCR data revealed that gene expression changes were generally modest and dispersed amongst a variety of known functional networks. Although genes showing major (>5-fold) differential expression were identified in a few instances, nearly all displayed transient temporal profiles, returning to WT levels by postnatal day (P) 21. These observations suggest that major defects in photoreceptor cell structure may induce early homeostatic responses, which function in a protective manner to promote cell viability. We identified a single key gene, Egr1, that was dysregulated in a sustained fashion in rds rod photoreceptors and retina. Egr1 upregulation was associated with microglial activation and migration into the outer retina at times subsequent to the major peak of photoreceptor cell death. Interestingly, this response was accompanied by neurotrophic factor upregulation. We hypothesize that activation of Egr1 and neurotrophic factors may represent a protective immune mechanism which contributes to the characteristically slow retinal degeneration of the rds mouse model.
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MESH Headings
- Animals
- Antigens, CD/metabolism
- Antigens, Differentiation, Myelomonocytic/metabolism
- Disease Models, Animal
- Early Growth Response Protein 1/metabolism
- Gene Expression Profiling
- Gene Expression Regulation
- Genetic Diseases, Inborn/genetics
- Genetic Diseases, Inborn/immunology
- Genetic Diseases, Inborn/pathology
- Genetic Diseases, Inborn/prevention & control
- Homeostasis/genetics
- Mice
- Mice, Inbred C57BL
- Microglia/metabolism
- Microglia/pathology
- Nerve Growth Factors/genetics
- Nerve Growth Factors/metabolism
- Neuroprotective Agents/metabolism
- Oligonucleotide Array Sequence Analysis
- Photoreceptor Cells, Vertebrate/immunology
- Photoreceptor Cells, Vertebrate/metabolism
- Photoreceptor Cells, Vertebrate/pathology
- Polymerase Chain Reaction
- Reproducibility of Results
- Retinal Degeneration/genetics
- Retinal Degeneration/immunology
- Retinal Degeneration/pathology
- Retinal Degeneration/prevention & control
- Up-Regulation/genetics
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Affiliation(s)
- Yagya V. Sharma
- Eye Research Institute, Oakland University, Rochester, Michigan, United States of America
| | - Radu I. Cojocaru
- Neurobiology Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Linda M. Ritter
- Eye Research Institute, Oakland University, Rochester, Michigan, United States of America
| | - Nidhi Khattree
- Eye Research Institute, Oakland University, Rochester, Michigan, United States of America
| | - Matthew Brooks
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States of America
- Neurobiology Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Alison Scott
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Anand Swaroop
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States of America
- Neurobiology Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Andrew F. X. Goldberg
- Eye Research Institute, Oakland University, Rochester, Michigan, United States of America
- * E-mail:
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Hedstrom L. The dynamic determinants of reaction specificity in the IMPDH/GMPR family of (β/α)(8) barrel enzymes. Crit Rev Biochem Mol Biol 2012; 47:250-63. [PMID: 22332716 DOI: 10.3109/10409238.2012.656843] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The inosine monophosphate dehydrogenase (IMPDH)/guanosine monophosphate reductase (GMPR) family of (β/α)(8) enzymes presents an excellent opportunity to investigate how subtle changes in enzyme structure change reaction specificity. IMPDH and GMPR bind the same ligands with similar affinities and share a common set of catalytic residues. Both enzymes catalyze a hydride transfer reaction involving a nicotinamide cofactor hydride, and both reactions proceed via the same covalent intermediate. In the case of IMPDH, this intermediate reacts with water, while in GMPR it reacts with ammonia. In both cases, the two chemical transformations are separated by a conformational change. In IMPDH, the conformational change involves a mobile protein flap while in GMPR, the cofactor moves. Thus reaction specificity is controlled by differences in dynamics, which in turn are controlled by residues outside the active site. These findings have some intriguing implications for the evolution of the IMPDH/GMPR family.
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Affiliation(s)
- Lizbeth Hedstrom
- Departments of Biology and Chemistry, Brandeis University, Waltham, MA 02454, USA.
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33
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A p53-inducible microRNA-34a downregulates Ras signaling by targeting IMPDH. Biochem Biophys Res Commun 2012; 418:682-8. [PMID: 22301190 DOI: 10.1016/j.bbrc.2012.01.077] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Accepted: 01/17/2012] [Indexed: 12/24/2022]
Abstract
p53 is a well-known transcription factor that controls cell cycle arrest and cell death in response to a wide range of stresses. Moreover, p53 regulates glucose metabolism and its mutation results in the metabolic switch to the Warburg effect found in cancer cells. Nucleotide biosynthesis is also critical for cell proliferation and the cell division cycle. Nonetheless, little is known about whether p53 regulates nucleotide biosynthesis. Here we demonstrated that p53-inducible microRNA-34a (miR-34a) repressed inosine 5'-monophosphate dehydrogenase (IMPDH), a rate-limiting enzyme of de novo GTP biosynthesis. Treatment with anti-miR-34a inhibitor relieved the expression of IMPDH upon DNA damage. Ultimately, miR-34a-mediated inhibition of IMPDH resulted in repressed activation of the GTP-dependent Ras signaling pathway. In summary, we suggest that p53 has a novel function in regulating purine biosynthesis, aided by miR-34a-dependent IMPDH repression.
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34
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McGrew DA, Hedstrom L. Towards a Pathological Mechanism for IMPDH1-Linked Retinitis Pigmentosa. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 723:539-45. [DOI: 10.1007/978-1-4614-0631-0_68] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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35
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Baykov AA, Tuominen HK, Lahti R. The CBS domain: a protein module with an emerging prominent role in regulation. ACS Chem Biol 2011; 6:1156-63. [PMID: 21958115 DOI: 10.1021/cb200231c] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Regulatory CBS (cystathionine β-synthase) domains exist as two or four tandem copies in thousands of cytosolic and membrane-associated proteins from all kingdoms of life. Mutations in the CBS domains of human enzymes and membrane channels are associated with an array of hereditary diseases. Four CBS domains encoded within a single polypeptide or two identical polypeptides (each having a pair of CBS domains at the subunit interface) form a highly conserved disk-like structure. CBS domains act as autoinhibitory regulatory units in some proteins and activate or further inhibit protein function upon binding to adenosine nucleotides (AMP, ADP, ATP, S-adenosyl methionine, NAD, diadenosine polyphosphates). As a result of the differential effects of the nucleotides, CBS domain-containing proteins can sense cell energy levels. Significant conformational changes are induced in CBS domains by bound ligands, highlighting the structural basis for their effects.
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Affiliation(s)
- Alexander A. Baykov
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119899, Russia
| | - Heidi K. Tuominen
- Department of Biochemistry and Food Chemistry, University of Turku, Turku FIN-20014, Finland
| | - Reijo Lahti
- Department of Biochemistry and Food Chemistry, University of Turku, Turku FIN-20014, Finland
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36
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Investigating the mechanism of disease in the RP10 form of retinitis pigmentosa. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011. [PMID: 20238057 DOI: 10.1007/978-1-4419-1399-9_62] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register]
Abstract
Retinitis pigmentosa (RP) is a disease characterized by its vast heterogeneity. Many genes are associated with RP, and the disease causing mutations identified in these genes are even more numerous. To date there are 15 genes that cause autosomal dominant RP (adRP) alone. The role of some of these genes, while complex and not completely understood, is somewhat intuitive in that they are involved in pathways such as phototransduction. However, the role of other genes in retinal disease is not as predictable due to their ubiquitous function and/or expression. One such gene is inosine monophosphate dehydrogenase 1 (IMPDH1) IMPDH1 is a gene involved in de novo purine synthesis and is ubiquitously expressed. IMPDH1 mutations account for 2% of all adRP cases and are a rare cause of Leiber Congenital Amaurosis. Despite its ubiquitous expression missense mutations in this gene cause only retinal degeneration. This paradox of tissue specific disease in the presence of ubiquitous expression has only recently begun to be explained. We have shown in a recent study that novel retinal isoforms of IMPDH1 exist and may account for the tissue specificity of disease. We have gone on to characterize these retinal isoforms both in our laboratory and in collaboration with Dr. Lizbeth Hedstrom's laboratory at Brandeis University (Waltham, MA) in order to understand more about them. We believe that through clarifying the mechanism of disease in RP10 we will be equipped to consider treatment options for this disease.
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Hedstrom L, Liechti G, Goldberg JB, Gollapalli DR. The antibiotic potential of prokaryotic IMP dehydrogenase inhibitors. Curr Med Chem 2011; 18:1909-18. [PMID: 21517780 DOI: 10.2174/092986711795590129] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Accepted: 04/04/2011] [Indexed: 12/30/2022]
Abstract
Inosine 5'-monophosphate dehydrogenase (IMPDH) catalyzes the first committed step of guanosine 5'-monophosphate (GMP) biosynthesis, and thus regulates the guanine nucleotide pool, which in turn governs proliferation. Human IMPDHs are validated targets for immunosuppressive, antiviral and anticancer drugs, but as yet microbial IMPDHs have not been exploited in antimicrobial chemotherapy. Selective inhibitors of IMPDH from Cryptosporidium parvum have recently been discovered that display anti-parasitic activity in cell culture models of infection. X-ray crystal structure and mutagenesis experiments identified the structural features that determine inhibitor susceptibility. These features are found in IMPDHs from a wide variety of pathogenic bacteria, including select agents and multiply drug resistant strains. A second generation inhibitor displays antibacterial activity against Helicobacter pylori, demonstrating the antibiotic potential of IMPDH inhibitors.
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Affiliation(s)
- L Hedstrom
- Brandeis University, Departments of Biology, Waltham, MA 02454-9110, USA.
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Mactier S, Henrich S, Che Y, Kohnke PL, Christopherson RI. Comprehensive Proteomic Analysis of the Effects of Purine Analogs on Human Raji B-Cell Lymphoma. J Proteome Res 2011; 10:1030-42. [DOI: 10.1021/pr100803b] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Swetlana Mactier
- School of Molecular Bioscience, University of Sydney, Sydney, NSW 2006, Australia
| | - Silke Henrich
- School of Molecular Bioscience, University of Sydney, Sydney, NSW 2006, Australia
| | - Yiping Che
- School of Molecular Bioscience, University of Sydney, Sydney, NSW 2006, Australia
| | - Philippa L. Kohnke
- School of Molecular Bioscience, University of Sydney, Sydney, NSW 2006, Australia
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Bramall AN, Wright AF, Jacobson SG, McInnes RR. The genomic, biochemical, and cellular responses of the retina in inherited photoreceptor degenerations and prospects for the treatment of these disorders. Annu Rev Neurosci 2011; 33:441-72. [PMID: 20572772 DOI: 10.1146/annurev-neuro-060909-153227] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The association of more than 140 genes with human photoreceptor degenerations, together with studies of animal models of these monogenic diseases, has provided great insight into their pathogenesis. Here we review the responses of the retina to photoreceptor mutations, including mechanisms of photoreceptor death. We discuss the roles of oxidative metabolism, mitochondrial reactive oxygen species, metabolic stress, protein misfolding, and defects in ciliary proteins, as well as the responses of Müller glia, microglia, and the retinal vasculature. Finally, we report on potential pharmacologic and biologic therapies, the critical role of histopathology as a prerequisite to treatment, and the exciting promise of gene therapy in animal models and in phase 1 trials in humans.
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Affiliation(s)
- Alexa N Bramall
- Programs in Genetics and Developmental Biology, The Research Institute, The Hospital for Sick Children, Toronto M5G1L7, Canada.
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Zhang ZW, Cheng J, Xu F, Yuan M, Du JB, Shang J, Wang Y, Du L, Li ZL, Yuan S. Mammal cells double their total RNAs against diabetes, ischemia reperfusion and malaria-induced oxidative stress. Mol Med 2010; 17:533-41. [PMID: 21152696 DOI: 10.2119/molmed.2010.00155] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Accepted: 12/02/2010] [Indexed: 01/08/2023] Open
Abstract
Total cellular RNA level is stable usually, although it may increase gradually during growth or decrease gradually under certain stressors. However, we found that mammal cell RNAs could be doubled within 24 h in response to free heme accumulation (ischemia reperfusion and malaria infection) or a high level of glucose treatment (diabetes). Clinical investigations in rats showed that pretreatment with heme (24 h for doubling total RNAs) alleviated oxidative damages caused by diabetes, and pretreatment with glucose (24 h for trebling total RNAs) alleviated oxidative damages caused by ischemia reperfusion or malaria infection. Therefore, this rapid RNA amplification may play an important role in mammal adaptation to diabetes, ischemia reperfusion and malaria infection-derived oxidative stress. This rapid RNA amplification is derived from glucose and heme, but not from their accompanying reactive oxygen species. Hexokinases endure glucose-derived reactive oxygen species accumulation but are not related glucose-derived RNA amplification. In contrast, the TATA box-binding protein (TBP) mediates all glucose- and heme-induced RNA amplification in mammal cells.
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Affiliation(s)
- Zhong-Wei Zhang
- College of Resources and Environmental Sciences, Sichuan Agriculture University, Chengdu, China
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Tam LCS, Kiang AS, Campbell M, Keaney J, Farrar GJ, Humphries MM, Kenna PF, Humphries P. Prevention of autosomal dominant retinitis pigmentosa by systemic drug therapy targeting heat shock protein 90 (Hsp90). Hum Mol Genet 2010; 19:4421-36. [PMID: 20817636 DOI: 10.1093/hmg/ddq369] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Retinitis pigmentosa (RP) is the most prevalent cause of registered visual handicap among working aged populations of developed countries. Up to 40% of autosomal dominant cases of disease are caused by mutations within the rhodopsin, RDS-peripherin and inosine 5'-monophosphate dehydrogenase type 1 (IMPDH1) genes, at least 30 mutations within which give rise to proteins that cause disease pathology by misfolding and aggregation. Given the genetic complexity of this disease, therapies that simultaneously target multiple mutations are of substantial logistic and economic significance. We show here, in a murine model of autosomal dominant RP (RP10) involving expression of an Arg224Pro mutation within the IMPDH1 gene, that treatment with the low-molecular-weight drug, 17-allylamino-17-demethoxygeldanamycin (17-AAG), an ansamycin antibiotic that binds to heat shock protein Hsp90, activating a heat shock response in mammalian cells, protects photoreceptors against degeneration induced by aggregating mutant IMPDH1 protein, systemic delivery of this low-molecular-weight drug to the retina being facilitated by RNA interference-mediated modulation of the inner-blood retina barrier. 17-AAG has an orphan drug status and is in current clinical use for the treatment of non-ocular diseases. These data show that a single low-molecular-weight drug has the potential to suppress a wide range of mutant proteins causing RP.
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Affiliation(s)
- Lawrence C S Tam
- The Ocular Genetics Unit, Department of Genetics, Trinity College Dublin, Dublin 2, Ireland
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Chen L, Wilson DJ, Xu Y, Aldrich CC, Felczak K, Sham YY, Pankiewicz KW. Triazole-linked inhibitors of inosine monophosphate dehydrogenase from human and Mycobacterium tuberculosis. J Med Chem 2010; 53:4768-78. [PMID: 20491506 DOI: 10.1021/jm100424m] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The modular nature of nicotinamide adenine dinucleotide (NAD)-mimicking inosine monophsophate dehydrogenase (IMPDH) inhibitors has prompted us to investigate novel mycophenolic adenine dinucleotides (MAD) in which 1,2,3-triazole linkers were incorporated as isosteric replacements of the pyrophosphate linker. Synthesis and evaluation of these inhibitors led to identification of low nanomolar inhibitors of human IMPDH and more importantly the first potent inhibitor of IMPDH from Mycobacterium tuberculosis (mtIMPDH). Computational studies of these IMPDH enzymes helped rationalize the observed structure-activity relationships. Additionally, the first cloning, expression, purification and characterization of mtIMPDH is reported.
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Affiliation(s)
- Liqiang Chen
- Center for Drug Design, Academic Health Center, University of Minnesota, 516 Delaware Street SE, Minneapolis, Minnesota 55455, USA.
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Wright AF, Chakarova CF, Abd El-Aziz MM, Bhattacharya SS. Photoreceptor degeneration: genetic and mechanistic dissection of a complex trait. Nat Rev Genet 2010; 11:273-84. [PMID: 20212494 DOI: 10.1038/nrg2717] [Citation(s) in RCA: 445] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Affiliation(s)
- Lizbeth Hedstrom
- Department of Biology, Brandeis University, MS009, 415 South Street, Waltham, Massachusetts 02454, USA.
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Pimkin M, Pimkina J, Markham GD. A regulatory role of the Bateman domain of IMP dehydrogenase in adenylate nucleotide biosynthesis. J Biol Chem 2009; 284:7960-9. [PMID: 19153081 DOI: 10.1074/jbc.m808541200] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Bateman domain (CBS subdomain) of IMP dehydrogenase (IMPDH), a rate-limiting enzyme of the de novo GMP biosynthesis, is evolutionarily conserved but has no established function. Deletion of the Bateman domain has no effect on the in vitro IMPDH activity. We report that in vivo deletion of the Bateman domain of IMPDH in Escherichia coli (guaB(DeltaCBS)) sensitizes the bacterium to growth arrest by adenosine and inosine. These nucleosides exert their growth inhibitory effect via a dramatic increase in the intracellular adenylate nucleotide pool, which results in the enhanced allosteric inhibition of PRPP synthetase and consequently a PRPP deficit. The ensuing starvation for pyrimidine nucleotides culminates in growth arrest. Thus, deletion of the Bateman domain of IMPDH derepresses the synthesis of AMP from IMP. The growth inhibitory effect of inosine can be rescued by second-site suppressor mutations in the genes responsible for the conversion of inosine to AMP (gsk, purA, and purB) as well as by the prsA1 allele, which encodes a PRPP synthetase that is insensitive to allosteric inhibition by adenylate nucleotides. Importantly, the guaB(DeltaCBS) phenotype can be complemented in trans by a mutant guaB allele, which encodes a catalytically disabled IMPDH(C305A) protein containing an intact Bateman domain. We conclude that the Bateman domain of IMPDH is a negative trans-regulator of adenylate nucleotide synthesis, and that this role is independent of the catalytic function of IMPDH in the de novo GMP biosynthesis.
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Affiliation(s)
- Maxim Pimkin
- Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA
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