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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 2024:10.1007/s10930-024-10202-3. [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] [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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2
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Takita S, Jahan S, Imanishi S, Harikrishnan H, LePage D, Mann RJ, Conlon RA, Miyagi M, Imanishi Y. Rhodopsin mislocalization drives ciliary dysregulation in a novel autosomal dominant retinitis pigmentosa knock-in mouse model. FASEB J 2024; 38:e23606. [PMID: 38648465 PMCID: PMC11047207 DOI: 10.1096/fj.202302260rr] [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: 11/02/2023] [Revised: 03/22/2024] [Accepted: 03/29/2024] [Indexed: 04/25/2024]
Abstract
Rhodopsin mislocalization encompasses various blind conditions. Rhodopsin mislocalization is the primary factor leading to rod photoreceptor dysfunction and degeneration in autosomal dominant retinitis pigmentosa (adRP) caused by class I mutations. In this study, we report a new knock-in mouse model that harbors a class I Q344X mutation in the endogenous rhodopsin gene, which causes rod photoreceptor degeneration in an autosomal dominant pattern. In RhoQ344X/+ mice, mRNA transcripts from the wild-type (Rho) and RhoQ344X mutant rhodopsin alleles are expressed at equal levels. However, the amount of RHOQ344X mutant protein is 2.7 times lower than that of wild-type rhodopsin, a finding consistent with the rapid degradation of the mutant protein. Immunofluorescence microscopy indicates that RHOQ344X is mislocalized to the inner segment and outer nuclear layers of rod photoreceptors in both RhoQ344X/+ and RhoQ344X/Q344X mice, confirming the essential role of the C-terminal VxPx motif in promoting OS delivery of rhodopsin. The mislocalization of RHOQ344X is associated with the concurrent mislocalization of wild-type rhodopsin in RhoQ344X/+ mice. To understand the global changes in proteostasis, we conducted quantitative proteomics analysis and found attenuated expression of rod-specific OS membrane proteins accompanying reduced expression of ciliopathy causative gene products, including constituents of BBSome and axonemal dynein subunit. Those studies unveil a novel negative feedback regulation involving ciliopathy-associated proteins. In this process, a defect in the trafficking signal leads to a reduced quantity of the trafficking apparatus, culminating in a widespread reduction in the transport of ciliary proteins.
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Affiliation(s)
- Shimpei Takita
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Sultana Jahan
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Sanae Imanishi
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Hemavathy Harikrishnan
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - David LePage
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | - Rachel J. Mann
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | - Ronald A. Conlon
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | - Masaru Miyagi
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | - Yoshikazu Imanishi
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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3
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Calise SJ, O’Neill AG, Burrell AL, Dickinson MS, Molfino J, Clarke C, Quispe J, Sokolov D, Buey RM, Kollman JM. Light-sensitive phosphorylation regulates retinal IMPDH1 activity and filament assembly. J Cell Biol 2024; 223:e202310139. [PMID: 38323936 PMCID: PMC10849882 DOI: 10.1083/jcb.202310139] [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: 10/27/2023] [Revised: 01/11/2024] [Accepted: 01/23/2024] [Indexed: 02/08/2024] Open
Abstract
Inosine monophosphate dehydrogenase (IMPDH) is the rate-limiting enzyme in guanosine triphosphate (GTP) synthesis and assembles into filaments in cells, which desensitizes the enzyme to feedback inhibition and boosts nucleotide production. The vertebrate retina expresses two splice variants IMPDH1(546) and IMPDH1(595). In bovine retinas, residue S477 is preferentially phosphorylated in the dark, but the effects on IMPDH1 activity and regulation are unclear. Here, we generated phosphomimetic mutants to investigate structural and functional consequences of S477 phosphorylation. The S477D mutation resensitized both variants to GTP inhibition but only blocked assembly of IMPDH1(595) filaments. Cryo-EM structures of both variants showed that S477D specifically blocks assembly of a high-activity assembly interface, still allowing assembly of low-activity IMPDH1(546) filaments. Finally, we discovered that S477D exerts a dominant-negative effect in cells, preventing endogenous IMPDH filament assembly. By modulating the structure and higher-order assembly of IMPDH, S477 phosphorylation acts as a mechanism for downregulating retinal GTP synthesis in the dark when nucleotide turnover is decreased.
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Affiliation(s)
- S. John Calise
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Audrey G. O’Neill
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Anika L. Burrell
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | | | - Josephine Molfino
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Charlie Clarke
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Joel Quispe
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - David Sokolov
- 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
| | - Justin M. Kollman
- Department of Biochemistry, University of Washington, Seattle, WA, USA
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4
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Ayoub N, Gedeon A, Munier-Lehmann H. A journey into the regulatory secrets of the de novo purine nucleotide biosynthesis. Front Pharmacol 2024; 15:1329011. [PMID: 38444943 PMCID: PMC10912719 DOI: 10.3389/fphar.2024.1329011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 02/01/2024] [Indexed: 03/07/2024] Open
Abstract
De novo purine nucleotide biosynthesis (DNPNB) consists of sequential reactions that are majorly conserved in living organisms. Several regulation events take place to maintain physiological concentrations of adenylate and guanylate nucleotides in cells and to fine-tune the production of purine nucleotides in response to changing cellular demands. Recent years have seen a renewed interest in the DNPNB enzymes, with some being highlighted as promising targets for therapeutic molecules. Herein, a review of two newly revealed modes of regulation of the DNPNB pathway has been carried out: i) the unprecedent allosteric regulation of one of the limiting enzymes of the pathway named inosine 5'-monophosphate dehydrogenase (IMPDH), and ii) the supramolecular assembly of DNPNB enzymes. Moreover, recent advances that revealed the therapeutic potential of DNPNB enzymes in bacteria could open the road for the pharmacological development of novel antibiotics.
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Affiliation(s)
- Nour Ayoub
- Institut Pasteur, Université Paris Cité, INSERM UMRS-1124, Paris, France
| | - Antoine Gedeon
- Sorbonne Université, École Normale Supérieure, Université PSL, CNRS UMR7203, Laboratoire des Biomolécules, LBM, Paris, France
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5
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Yalaz C, Bridges E, Alham NK, Zois CE, Chen J, Bensaad K, Miar A, Pires E, Muschel RJ, McCullagh JSO, Harris AL. Cone photoreceptor phosphodiesterase PDE6H inhibition regulates cancer cell growth and metabolism, replicating the dark retina response. Cancer Metab 2024; 12:5. [PMID: 38350962 PMCID: PMC10863171 DOI: 10.1186/s40170-023-00326-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 11/24/2023] [Indexed: 02/15/2024] Open
Abstract
BACKGROUND PDE6H encodes PDE6γ', the inhibitory subunit of the cGMP-specific phosphodiesterase 6 in cone photoreceptors. Inhibition of PDE6, which has been widely studied for its role in light transduction, increases cGMP levels. The purpose of this study is to characterise the role of PDE6H in cancer cell growth. METHODS From an siRNA screen for 487 genes involved in metabolism, PDE6H was identified as a controller of cell cycle progression in HCT116 cells. Role of PDE6H in cancer cell growth and metabolism was studied through the effects of its depletion on levels of cell cycle controllers, mTOR effectors, metabolite levels, and metabolic energy assays. Effect of PDE6H deletion on tumour growth was also studied in a xenograft model. RESULTS PDE6H knockout resulted in an increase of intracellular cGMP levels, as well as changes to the levels of nucleotides and key energy metabolism intermediates. PDE6H knockdown induced G1 cell cycle arrest and cell death and reduced mTORC1 signalling in cancer cell lines. Both knockdown and knockout of PDE6H resulted in the suppression of mitochondrial function. HCT116 xenografts revealed that PDE6H deletion, as well as treatment with the PDE5/6 inhibitor sildenafil, slowed down tumour growth and improved survival, while sildenafil treatment did not have an additive effect on slowing the growth of PDE6γ'-deficient tumours. CONCLUSIONS Our results indicate that the changes in cGMP and purine pools, as well as mitochondrial function which is observed upon PDE6γ' depletion, are independent of the PKG pathway. We show that in HCT116, PDE6H deletion replicates many effects of the dark retina response and identify PDE6H as a new target in preventing cancer cell proliferation and tumour growth.
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Affiliation(s)
- Ceren Yalaz
- Molecular Oncology Laboratories, Department of Medical Oncology, John Radcliffe Hospital, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK.
| | - Esther Bridges
- Molecular Oncology Laboratories, Department of Medical Oncology, John Radcliffe Hospital, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Nasullah K Alham
- Department of Engineering Science, Institute of Biomedical Engineering (IBME), University of Oxford, Old Road Campus Research Building, Oxford, OX3 7DQ, UK
| | - Christos E Zois
- Molecular Oncology Laboratories, Department of Medical Oncology, John Radcliffe Hospital, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Jianzhou Chen
- Department of Oncology, University of Oxford, Old Road Campus Research Building, Oxford, OX3 7DQ, UK
| | - Karim Bensaad
- Molecular Oncology Laboratories, Department of Medical Oncology, John Radcliffe Hospital, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Ana Miar
- Department of Oncology, University of Oxford, Old Road Campus Research Building, Oxford, OX3 7DQ, UK
| | - Elisabete Pires
- Department of Chemistry, University of Oxford, Mansfield Road, Oxford, OX1 3TA, UK
| | - Ruth J Muschel
- Department of Oncology, University of Oxford, Old Road Campus Research Building, Oxford, OX3 7DQ, UK
| | - James S O McCullagh
- Department of Chemistry, University of Oxford, Mansfield Road, Oxford, OX1 3TA, UK
| | - Adrian L Harris
- Molecular Oncology Laboratories, Department of Medical Oncology, John Radcliffe Hospital, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
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6
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Woulfe J, Munoz DG, Gray DA, Jinnah HA, Ivanova A. Inosine monophosphate dehydrogenase intranuclear inclusions are markers of aging and neuronal stress in the human substantia nigra. Neurobiol Aging 2024; 134:43-56. [PMID: 37992544 DOI: 10.1016/j.neurobiolaging.2023.11.005] [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: 08/22/2023] [Revised: 11/03/2023] [Accepted: 11/06/2023] [Indexed: 11/24/2023]
Abstract
We explored mechanisms involved in the age-dependent degeneration of human substantia nigra (SN) dopamine (DA) neurons. Owing to its important metabolic functions in post-mitotic neurons, we investigated the developmental and age-associated changes in the purine biosynthetic enzyme inosine monophosphate dehydrogenase (IMPDH). Tissue microarrays prepared from post-mortem samples of SN from 85 neurologically intact participants humans spanning the age spectrum were immunostained for IMPDH combined with other proteins. SN DA neurons contained two types of IMPDH structures: cytoplasmic IMPDH filaments and intranuclear IMPDH inclusions. The former were not age-restricted and may represent functional units involved in sustaining purine nucleotide supply in these highly metabolically active cells. The latter showed age-associated changes, including crystallization, features reminiscent of pathological inclusion bodies, and spatial associations with Marinesco bodies; structures previously associated with SN neuron dysfunction and death. We postulate dichotomous roles for these two subcellularly distinct IMPDH structures and propose a nucleus-based model for a novel mechanism of SN senescence that is independent of previously known neurodegeneration-associated proteins.
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Affiliation(s)
- John Woulfe
- Neuroscience Program, The Ottawa Hospital Research Institute, Ottawa, Ontario, Canada; Department of Pathology and Laboratory Medicine, University of Ottawa, Ottawa, Ontario, Canada.
| | - David G Munoz
- Li Ka Shing Knowledge Institute & Department of Laboratory Medicine & Pathobiology, University of Toronto, Toronto, Ontario, Canada; Department of Laboratory Medicine, St. Michael's Hospital, Unity Health, University of Toronto, Toronto, Ontario, Canada
| | - Douglas A Gray
- Center for Cancer Therapeutics, The Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Hyder A Jinnah
- Departments of Neurology, Human Genetics & Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
| | - Alyona Ivanova
- The Arthur and Sonia Labatt Brain Tumor Research Center, The Hospital for Sick Children and Neurosurgery Research Department, St. Michael's Hospital, Toronto Unity Health, Toronto, Ontario, Canada
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7
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Lee TJ, Sasaki Y, Ruzycki PA, Ban N, Lin JB, Wu HT, Santeford A, Apte RS. Catalytic isoforms of AMP-activated protein kinase differentially regulate IMPDH activity and photoreceptor neuron function. JCI Insight 2024; 9:e173707. [PMID: 38227383 DOI: 10.1172/jci.insight.173707] [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: 07/10/2023] [Accepted: 01/10/2024] [Indexed: 01/17/2024] Open
Abstract
AMP-activated protein kinase (AMPK) plays a crucial role in maintaining ATP homeostasis in photoreceptor neurons. AMPK is a heterotrimeric protein consisting of α, β, and γ subunits. The independent functions of the 2 isoforms of the catalytic α subunit, PRKAA1 and PRKAA2, are uncharacterized in specialized neurons, such as photoreceptors. Here, we demonstrate in mice that rod photoreceptors lacking PRKAA2, but not PRKAA1, showed altered levels of cGMP, GTP, and ATP, suggesting isoform-specific regulation of photoreceptor metabolism. Furthermore, PRKAA2-deficient mice displayed visual functional deficits on electroretinography and photoreceptor outer segment structural abnormalities on transmission electron microscopy consistent with neuronal dysfunction, but not neurodegeneration. Phosphoproteomics identified inosine monophosphate dehydrogenase (IMPDH) as a molecular driver of PRKAA2-specific photoreceptor dysfunction, and inhibition of IMPDH improved visual function in Prkaa2 rod photoreceptor-knockout mice. These findings highlight a therapeutically targetable PRKAA2 isoform-specific function of AMPK in regulating photoreceptor metabolism and function through a potentially previously uncharacterized mechanism affecting IMPDH activity.
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Affiliation(s)
- Tae Jun Lee
- John F. Hardesty, MD Department of Ophthalmology and Visual Sciences
- Department of Developmental Biology; and
| | - Yo Sasaki
- Department of Genetics, Washington University in St. Louis School of Medicine, St. Louis, Missouri, USA
| | - Philip A Ruzycki
- John F. Hardesty, MD Department of Ophthalmology and Visual Sciences
- Department of Genetics, Washington University in St. Louis School of Medicine, St. Louis, Missouri, USA
| | - Norimitsu Ban
- Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | - Joseph B Lin
- John F. Hardesty, MD Department of Ophthalmology and Visual Sciences
| | | | - Andrea Santeford
- John F. Hardesty, MD Department of Ophthalmology and Visual Sciences
| | - Rajendra S Apte
- John F. Hardesty, MD Department of Ophthalmology and Visual Sciences
- Department of Developmental Biology; and
- Department of Medicine, Washington University in St. Louis School of Medicine, St. Louis, Missouri, USA
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8
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Yu J, Yuan H, Guo J, Dong Z, Li S, Fu Q, Aode B, Baoyin S, Bao L, Wu L. Combining multi-omics analysis to identify host-targeted targets for the control of Brucella infection. Microb Biotechnol 2023; 16:2345-2366. [PMID: 37882474 PMCID: PMC10686141 DOI: 10.1111/1751-7915.14307] [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: 10/29/2022] [Revised: 02/15/2023] [Accepted: 06/20/2023] [Indexed: 10/27/2023] Open
Abstract
Human infections caused by Brucella (called brucellosis) are among the most common zoonoses worldwide with an estimated 500,000 cases each year. Since chronic Brucella infections are extremely difficult to treat, there is an urgent need for more effective therapeutics. As a facultative intracellular bacterium, Brucella is strictly parasitic in the host cell. Here, we performed proteomic and transcriptomic and metabolomic analyses on Brucella infected patients, mice and cells that provided an extensive "map" of physiological changes in brucellosis patients and characterized the metabolic pathways essential to the response to infection, as well as the associated cellular response and molecular mechanisms. This is the first report utilizing multi-omics analysis to investigate the global response of proteins and metabolites associated with Brucella infection, and the data can provide a comprehensive insight to understand the mechanism of Brucella infection. We demonstrated that Brucella increased nucleotide synthesis in the host, consistent with increased biomass requirement. We also identified IMPDH2, a key regulatory complex that controls nucleotide synthesis during Brucella infection. Pharmacological targeting of IMPDH2, the rate-limiting enzyme in guanine nucleotide biosynthesis, efficiently inhibits B. abortus growth both in vitro and in vivo. Through screening a library of natural products, we identified oxymatrine, an alkaloid obtained primarily from Sophora roots, is a novel and selective IMPDH2 inhibitor. In further in vitro bacterial inhibition assays, oxymatrine effectively inhibited the growth of B. abortus, which was impaired by exogenous supplementation of guanosine, a salvage pathway of purine nucleotides. This moderately potent, structurally novel compound may provide clues for further design and development of efficient IMPDH2 inhibitors and also demonstrates the potential of natural compounds from plants against Brucella.
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Affiliation(s)
- Jiuwang Yu
- TCM Hospital of Mongolian Medicine in HohhotHohhotChina
| | - Hongwei Yuan
- Department of PathologyAffiliated Hospital of Inner Mongolia Medical UniversityHohhotChina
| | - Jiarong Guo
- TCM Hospital of Mongolian Medicine in HohhotHohhotChina
| | - Zhiheng Dong
- Department of PharmacyAffiliated Hospital of Inner Mongolia Medical UniversityHohhotChina
| | - Sha Li
- Department of PharmacyAffiliated Hospital of Inner Mongolia Medical UniversityHohhotChina
| | - Quan Fu
- Department of LaboratoryAffiliated Hospital of Inner Mongolia Medical UniversityHohhotChina
| | - Bilige Aode
- Department of Mongolian MedicineInner Mongolia Xilin Gol League Mongolian Medical HospitalXilinhaoteChina
| | - Sachula Baoyin
- Mongolia Medical SchoolInner Mongolia Medical UniversityHohhotChina
| | - Lidao Bao
- TCM Hospital of Mongolian Medicine in HohhotHohhotChina
| | - Lan Wu
- TCM Hospital of Mongolian Medicine in HohhotHohhotChina
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9
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Kopra K, Mahran R, Yli-Hollo T, Tabata S, Vuorinen E, Fujii Y, Vuorinen I, Ogawa-Iio A, Hirayama A, Soga T, Sasaki AT, Härmä H. Homogeneous luminescent quantitation of cellular guanosine and adenosine triphosphates (GTP and ATP) using QT-Luc GTP&ATP assay. Anal Bioanal Chem 2023; 415:6689-6700. [PMID: 37714971 PMCID: PMC10598090 DOI: 10.1007/s00216-023-04944-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 09/04/2023] [Accepted: 09/07/2023] [Indexed: 09/17/2023]
Abstract
Guanosine triphosphate (GTP) and adenosine triphosphate (ATP) are essential nucleic acid building blocks and serve as energy molecules for a wide range of cellular reactions. Cellular GTP concentration fluctuates independently of ATP and is significantly elevated in numerous cancers, contributing to malignancy. Quantitative measurement of ATP and GTP has become increasingly important to elucidate how concentration changes regulate cell function. Liquid chromatography-coupled mass spectrometry (LC-MS) and capillary electrophoresis-coupled MS (CE-MS) are powerful methods widely used for the identification and quantification of biological metabolites. However, these methods have limitations related to specialized instrumentation and expertise, low throughput, and high costs. Here, we introduce a novel quantitative method for GTP concentration monitoring (GTP-quenching resonance energy transfer (QRET)) in homogenous cellular extracts. CE-MS analysis along with pharmacological control of cellular GTP levels shows that GTP-QRET possesses high dynamic range and accuracy. Furthermore, we combined GTP-QRET with luciferase-based ATP detection, leading to a new technology, termed QT-LucGTP&ATP, enabling high-throughput compatible dual monitoring of cellular GTP and ATP in a homogenous fashion. Collectively, GTP-QRET and QT-LucGTP&ATP offer a unique, high-throughput opportunity to explore cellular energy metabolism, serving as a powerful platform for the development of novel therapeutics and extending its usability across a range of disciplines.
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Affiliation(s)
- Kari Kopra
- Department of Chemistry, University of Turku, Henrikinkatu 2, 20500, Turku, Finland.
| | - Randa Mahran
- Department of Chemistry, University of Turku, Henrikinkatu 2, 20500, Turku, Finland
| | - Titta Yli-Hollo
- Department of Chemistry, University of Turku, Henrikinkatu 2, 20500, Turku, Finland
| | - Sho Tabata
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata, 997-0052, Japan
| | - Emmiliisa Vuorinen
- Department of Chemistry, University of Turku, Henrikinkatu 2, 20500, Turku, Finland
| | - Yuki Fujii
- Department of Internal Medicine, University of Cincinnati College of Medicine, 3125 Eden Ave, Cincinnati, OH, 45267-0508, USA
| | - Iida Vuorinen
- Department of Chemistry, University of Turku, Henrikinkatu 2, 20500, Turku, Finland
| | - Aki Ogawa-Iio
- Department of Internal Medicine, University of Cincinnati College of Medicine, 3125 Eden Ave, Cincinnati, OH, 45267-0508, USA
| | - Akiyoshi Hirayama
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata, 997-0052, Japan
| | - Tomoyoshi Soga
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata, 997-0052, Japan
| | - Atsuo T Sasaki
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata, 997-0052, Japan
- Department of Internal Medicine, University of Cincinnati College of Medicine, 3125 Eden Ave, Cincinnati, OH, 45267-0508, USA
- Department of Clinical and Molecular Genetics, Hiroshima University Hospital, Hiroshima, 734-8551, Japan
| | - Harri Härmä
- Department of Chemistry, University of Turku, Henrikinkatu 2, 20500, Turku, Finland
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10
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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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11
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Calise SJ, O’Neill AG, Burrell AL, Dickinson MS, Molfino J, Clarke C, Quispe J, Sokolov D, Buey RM, Kollman JM. Light-sensitive phosphorylation regulates enzyme activity and filament assembly of human IMPDH1 retinal splice variants. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.21.558867. [PMID: 37790411 PMCID: PMC10542554 DOI: 10.1101/2023.09.21.558867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
Inosine monophosphate dehydrogenase (IMPDH) is the rate-limiting enzyme in de novo guanosine triphosphate (GTP) synthesis and is controlled by feedback inhibition and allosteric regulation. IMPDH assembles into micron-scale filaments in cells, which desensitizes the enzyme to feedback inhibition by GTP and boosts nucleotide production. The vertebrate retina expresses two tissue-specific splice variants IMPDH1(546) and IMPDH1(595). IMPDH1(546) filaments adopt high and low activity conformations, while IMPDH1(595) filaments maintain high activity. In bovine retinas, residue S477 is preferentially phosphorylated in the dark, but the effects on IMPDH1 activity and regulation are unclear. Here, we generated phosphomimetic mutants to investigate structural and functional consequences of phosphorylation in IMPDH1 variants. The S477D mutation re-sensitized both variants to GTP inhibition, but only blocked assembly of IMPDH1(595) filaments and not IMPDH1(546) filaments. Cryo-EM structures of both variants showed that S477D specifically blocks assembly of the high activity assembly interface, still allowing assembly of low activity IMPDH1(546) filaments. Finally, we discovered that S477D exerts a dominant-negative effect in cells, preventing endogenous IMPDH filament assembly. By modulating the structure and higher-order assembly of IMPDH, phosphorylation at S477 acts as a mechanism for downregulating retinal GTP synthesis in the dark, when nucleotide turnover is decreased. Like IMPDH1, many other metabolic enzymes dynamically assemble filamentous polymers that allosterically regulate activity. Our work suggests that posttranslational modifications may be yet another layer of regulatory control to finely tune activity by modulating filament assembly in response to changing metabolic demands.
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Affiliation(s)
- S. John Calise
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Audrey G. O’Neill
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Anika L. Burrell
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | | | - Josephine Molfino
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Charlie Clarke
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Joel Quispe
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - David Sokolov
- 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
| | - Justin M. Kollman
- Department of Biochemistry, University of Washington, Seattle, WA, USA
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12
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Keppeke GD, Chang CC, Zhang Z, Liu JL. Effect on cell survival and cytoophidium assembly of the adRP-10-related IMPDH1 missense mutation Asp226Asn. Front Cell Dev Biol 2023; 11:1234592. [PMID: 37731818 PMCID: PMC10507268 DOI: 10.3389/fcell.2023.1234592] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Accepted: 08/17/2023] [Indexed: 09/22/2023] Open
Abstract
Introduction: Inosine monophosphate dehydrogenase 1 (IMPDH1) is a critical enzyme in the retina, essential for the correct functioning of photoreceptor cells. Mutations in IMPDH1 have been linked to autosomal dominant retinitis pigmentosa subtype 10 (adRP-10), a genetic eye disorder. Some of these mutations such as the Asp226Asn (D226N) lead to the assembly of large filamentous structures termed cytoophidia. D226N also gives IMPDH1 resistance to feedback inhibition by GDP/GTP. This study aims to emulate the adRP-10 condition with a long-term expression of IMPDH1-D226N in vitro and explore cytoophidium assembly and cell survival. We also assessed whether the introduction of an additional mutation (Y12C) to disrupt the cytoophidium has an attenuating effect on the toxicity caused by the D226N mutation. Results: Expression of IMPDH1-D226N in HEp-2 cells resulted in cytoophidium assembly in ∼70% of the cells, but the presence of the Y12C mutation disrupted the filaments. Long-term cell survival was significantly affected by the presence of the D226N mutation, with a decrease of ∼40% in the cells expressing IMPDH1-D226N when compared to IMPDH1-WT; however, survival was significantly recovered in IMPDH1-Y12C/D226N, with only a ∼10% decrease when compared to IMPDH1-WT. On the other hand, the IMPDH1 expression level in the D226N-positive cells was <30% of that of the IMPDH1-WT-positive cells and only slightly higher in the Y12C/D226N, suggesting that although cell survival in Y12C/D226N was recovered, higher expression levels of the mutated IMPDH1 were not tolerated by the cells in the long term. Conclusion: The IMPDH1-D226N effect on photoreceptor cell survival may be the result of a sum of problems: nucleotide unbalance plus a toxic long-life cytoophidium, supported by the observation that by introducing Y12C in IMPDH1 the cytoophidium was disrupted and cell survival significantly recovered, but not the sensibility to GDP/GTP regulation since higher expression levels of IMPDH1-D226N were not tolerated.
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Affiliation(s)
- Gerson Dierley Keppeke
- Departamento de Ciencias Biomédicas, Facultad de Medicina, Universidad Católica del Norte, Coquimbo, Chile
- Rheumatology Division, Escola Paulista de Medicina, Universidade Federal de Sao Paulo, Sao Paulo, Brazil
| | - Chia-Chun Chang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- Institute of Biotechnology, National Taiwan University, Taipei, Taiwan
| | - Ziheng Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Ji-Long Liu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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13
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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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14
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Cellular and Molecular Mechanisms of Pathogenesis Underlying Inherited Retinal Dystrophies. Biomolecules 2023; 13:biom13020271. [PMID: 36830640 PMCID: PMC9953031 DOI: 10.3390/biom13020271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 01/23/2023] [Accepted: 01/27/2023] [Indexed: 02/04/2023] Open
Abstract
Inherited retinal dystrophies (IRDs) are congenital retinal degenerative diseases that have various inheritance patterns, including dominant, recessive, X-linked, and mitochondrial. These diseases are most often the result of defects in rod and/or cone photoreceptor and retinal pigment epithelium function, development, or both. The genes associated with these diseases, when mutated, produce altered protein products that have downstream effects in pathways critical to vision, including phototransduction, the visual cycle, photoreceptor development, cellular respiration, and retinal homeostasis. The aim of this manuscript is to provide a comprehensive review of the underlying molecular mechanisms of pathogenesis of IRDs by delving into many of the genes associated with IRD development, their protein products, and the pathways interrupted by genetic mutation.
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15
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Kwan JT, Ramsey DJ. Multimodal image alignment aids in the evaluation and monitoring of sector retinitis pigmentosa. Ophthalmic Genet 2023; 44:93-102. [PMID: 35769018 DOI: 10.1080/13816810.2022.2092755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
PURPOSE To present a semi-automated method of image alignment to aid in monitoring the progression of inherited retinal degenerations (IRDs). RESULTS A 22-year-old woman presented with nyctalopia and a family history of retinitis pigmentosa (RP), but with no prior genetic testing. Fundus examination showed a sectoral retinal degeneration involving the inferior and nasal retina with rare, pigmented deposits. Goldmann kinetic perimetry demonstrated corresponding superotemporal visual field defects. The best-corrected visual acuity was 20/20 in both eyes. Multimodal imaging delineated geographically restricted peripheral retinal degeneration extending to the inferior edge of the macula. Central visual function remained intact with normal multifocal electroretinography findings. Optical coherence tomography (OCT) through the leading edge of the retinal degeneration confirmed loss of the photoreceptor layer and associated retinal pigment epithelium. In the region of retinal degeneration, loss of vascular flow density was noted on optical coherence tomography angiography (OCTA). Genetic testing identified a pathologic sequence variant in RHO (c.68C>A, p.Pro23His), confirming autosomal dominant sector retinitis pigmentosa (SRP). Image alignment allowed for precise measurement of the progression of SRP over a period of 18 months. CONCLUSION SRP is a rare subtype of RP characterized by focal, typically inferior and nasal, retinal degeneration of the peripheral retina. Although the onset and extent of peripheral retinal degeneration varies, compared with RP, SRP typically progresses more slowly to involve the macula. In this report, we highlight the utility of image registration and alignment to aid in monitoring disease progression in IRDs by means of multimodal imaging.
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Affiliation(s)
- James T Kwan
- Department of Ophthalmology, Tufts University School of Medicine, Boston, Massachusetts, USA.,Department of Surgery, Division of Ophthalmology, Lahey Hospital & Medical Center, Burlington, Massachusetts, USA
| | - David J Ramsey
- Department of Ophthalmology, Tufts University School of Medicine, Boston, Massachusetts, USA.,Department of Surgery, Division of Ophthalmology, Lahey Hospital & Medical Center, Burlington, Massachusetts, USA
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16
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She X, Zhou Y, Liang Z, Wei J, Xie B, Zhang Y, Shen L. Metabolomic Study of a Rat Model of Retinal Detachment. Metabolites 2022; 12:metabo12111077. [PMID: 36355160 PMCID: PMC9699637 DOI: 10.3390/metabo12111077] [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: 08/30/2022] [Revised: 10/09/2022] [Accepted: 11/02/2022] [Indexed: 11/09/2022] Open
Abstract
Retinal detachment is a serious ocular disease leading to photoreceptor degeneration and vision loss. However, the mechanism of photoreceptor degeneration remains unclear. The aim of this study was to investigate the altered metabolism pathway and physiological changes after retinal detachment. Eight-week-old male SD rats were fed, and the model of retinal detachment was established by injecting hyaluronic acid into the retinal space. The rats were euthanized 3 days after RD, and the retinal tissues were sectioned for analysis. Untargeted lipid chromatography-mass spectrometry lipidomic was performed to analyze the metabolite changes. A total of 90 significant metabolites (34 in anionic and 56 in cationic models) were detected after retinal detachment. The main pathways were (1) histidine metabolism; (2) phenylalanine, tyrosine, and tryptophan biosynthesis; and (3) glycine, serine, and threonine metabolism. The key genes corresponding to each metabolic pathway were verified from the Gene Expression Omnibus (GEO) database of human retinal samples. The results indicated that the production of histamine by histidine decarboxylase from histidine reduced after RD (p < 0.05). Xanthine, hypoxanthine, guanine, and guanosine decreased after RD (p < 0.05). Decreased xanthine and hypoxanthine may reduce the antioxidant ability. The decreased guanosine could not provide enough sources for inosine monophosphate production. Tyrosine is an important neurotransmitter and was significantly reduced after RD (p < 0.05). Citrate was significantly reduced with the increase of ATP-citrate lyase enzyme (ACLY) (p < 0.05). We inferred that lipid oxidation might increase rather than lipid biogenesis. Thus, this study highlighted the main changes of metabolite and physiological process after RD. The results may provide important information for photoreceptor degeneration.
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Affiliation(s)
- Xiangjun She
- School of Ophthalmology, Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
| | - Yifan Zhou
- Department of Ophthalmology, Putuo Poeple’s Hospital, Tongji University, Shanghai 200070, China
| | - Zhi Liang
- School of Ophthalmology, Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
| | - Jin Wei
- Department of Ophthalmology, Shanghai General Hospital, National Clinical Research Center for Eye Diseases, Shanghai 200080, China
| | - Bintao Xie
- School of Ophthalmology, Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
- State Key Laboratory of Optometry, Ophthalmology, and Vision Science, Wenzhou 325027, China
| | - Yun Zhang
- School of Ophthalmology, Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
| | - Lijun Shen
- School of Ophthalmology, Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
- State Key Laboratory of Optometry, Ophthalmology, and Vision Science, Wenzhou 325027, China
- Zhejiang Provincial People’s Hospital, Affiliated People’s Hospital of Hangzhou Medical College, Shangtang Road 158#, Gongshu District, Hangzhou 310014, China
- Correspondence:
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17
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Darekar S, Laín S. Asymmetric inheritance of cytoophidia could contribute to determine cell fate and plasticity: The onset of alternative differentiation patterns in daughter cells may rely on the acquisition of either CTPS or IMPDH cytoophidia: The onset of alternative differentiation patterns in daughter cells may rely on the acquisition of either CTPS or IMPDH cytoophidia. Bioessays 2022; 44:e2200128. [PMID: 36209393 DOI: 10.1002/bies.202200128] [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: 07/01/2022] [Revised: 08/26/2022] [Accepted: 09/21/2022] [Indexed: 12/20/2022]
Abstract
Two enzymes involved in the synthesis of pyrimidine and purine nucleotides, CTP synthase (CTPS) and IMP dehydrogenase (IMPDH), can assemble into a single or very few large filaments called rods and rings (RR) or cytoophidia. Most recently, asymmetric cytoplasmic distribution of organelles during cell division has been described as a decisive event in hematopoietic stem cell fate. We propose that cytoophidia, which could be considered as membrane-less organelles, may also be distributed asymmetrically during mammalian cell division as previously described for Schizosaccharomyces pombe. Furthermore, because each type of nucleotide intervenes in distinct processes (e.g., membrane synthesis, glycosylation, and G protein-signaling), alterations in the rate of synthesis of specific nucleotide types could influence cell differentiation in multiple ways. Therefore, we hypothesize that whether a daughter cell inherits or not CTPS or IMPDH filaments determines its fate and that this asymmetric inheritance, together with the dynamic nature of these structures enables plasticity in a cell population.
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Affiliation(s)
- Suhas Darekar
- Department of Microbiology, Tumor and Cell Biology (MTC), Biomedicum, Karolinska Institutet, Stockholm, Sweden
| | - Sonia Laín
- Department of Microbiology, Tumor and Cell Biology (MTC), Biomedicum, Karolinska Institutet, Stockholm, Sweden
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18
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Xiao Q, Wang L, Zhang J, Zhong X, Guo Z, Yu J, Ma Y, Wu H. Activation of Wnt/β-Catenin Signaling Involves 660 nm Laser Radiation on Epithelium and Modulates Lipid Metabolism. Biomolecules 2022; 12:biom12101389. [PMID: 36291598 PMCID: PMC9599573 DOI: 10.3390/biom12101389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 09/10/2022] [Accepted: 09/20/2022] [Indexed: 11/17/2022] Open
Abstract
Research has proven that light treatment, specifically red light radiation, can provide more clinical benefits to human health. Our investigation was firstly conducted to characterize the tissue morphology of mouse breast post 660 nm laser radiation with low power and long-term exposure. RNA sequencing results revealed that light exposure with a higher intervention dosage could cause a number of differentially expressed genes compared with a low intervention dosage. Gene ontology analysis, protein–protein interaction network analysis, and gene set enrichment analysis results suggested that 660 nm light exposure can activate more transcription-related pathways in HC11 breast epithelial cells, and these pathways may involve modulating critical gene expression. To consider the critical role of the Wnt/T-catenin pathway in light-induced modulation, we hypothesized that this pathway might play a major role in response to 660 nm light exposure. To validate our hypothesis, we conducted qRT-PCR, immunofluorescence staining, and Western blot assays, and relative results corroborated that laser radiation could promote expression levels of β-catenin and relative phosphorylation. Significant changes in metabolites and pathway analysis revealed that 660 nm laser could affect nucleotide metabolism by regulating purine metabolism. These findings suggest that the Wnt/β-catenin pathway may be the major sensor for 660 nm laser radiation, and it may be helpful to rescue drawbacks or side effects of 660 nm light exposure through relative interventional agents.
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Affiliation(s)
- Qiyang Xiao
- School of Artificial Intelligence, Henan University, Zhengzhou 450046, China
| | - Lijing Wang
- School of Life Sciences, Henan University, Kaifeng 475000, China
| | - Juling Zhang
- Center for Faculty Development, South China Normal University, Guangzhou 510631, China
| | - Xinyu Zhong
- School of Life Sciences, Henan University, Kaifeng 475000, China
| | - Zhou Guo
- School of Life Sciences, Henan University, Kaifeng 475000, China
| | - Jiahao Yu
- Shandong Zhongbaokang Medical Implements Co., Ltd., Zibo 255000, China
| | - Yuanyuan Ma
- School of Pharmacy, Henan University, Kaifeng 475000, China
| | - Haigang Wu
- School of Artificial Intelligence, Henan University, Zhengzhou 450046, China
- Correspondence:
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19
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Wolff DW, Bianchi-Smiraglia A, Nikiforov MA. Compartmentalization and regulation of GTP in control of cellular phenotypes. Trends Mol Med 2022; 28:758-769. [PMID: 35718686 PMCID: PMC9420775 DOI: 10.1016/j.molmed.2022.05.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 05/26/2022] [Accepted: 05/27/2022] [Indexed: 10/18/2022]
Abstract
Genetic or pharmacological inhibition of enzymes involved in GTP biosynthesis has substantial biological effects, underlining the need to better understand the function of GTP levels in regulation of cellular processes and the significance of targeting GTP biosynthesis enzymes for therapeutic intervention. Our current understanding of spatiotemporal regulation of GTP metabolism and its role in physiological and pathological cellular processes is far from complete. Novel methodologies such as genetically encoded sensors of free GTP offered insights into intracellular distribution and function of GTP molecules. In the current Review, we provide analysis of recent discoveries in the field of GTP metabolism and evaluate the key enzymes as molecular targets.
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Affiliation(s)
- David W Wolff
- Department of Biomedical Engineering, Pratt School of Engineering, Duke University, Durham, NC 27708, USA.
| | - Anna Bianchi-Smiraglia
- Department of Cell Stress Biology, Roswell Park Comprehensive Cancer Center, Buffalo, NY 14203, USA
| | - Mikhail A Nikiforov
- Department of Biomedical Engineering, Pratt School of Engineering, Duke University, Durham, NC 27708, USA; Department of Pathology, Duke University School of Medicine, Durham, NC 27710, USA.
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20
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Buey RM, Fernández‐Justel D, Jiménez A, Revuelta JL. The gateway to guanine nucleotides: Allosteric regulation of IMP dehydrogenases. Protein Sci 2022; 31:e4399. [PMID: 36040265 PMCID: PMC9375230 DOI: 10.1002/pro.4399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 07/07/2022] [Accepted: 07/19/2022] [Indexed: 11/12/2022]
Abstract
Inosine 5′‐monophosphate dehydrogenase (IMPDH) is an evolutionarily conserved enzyme that mediates the first committed step in de novo guanine nucleotide biosynthetic pathway. It is an essential enzyme in purine nucleotide biosynthesis that modulates the metabolic flux at the branch point between adenine and guanine nucleotides. IMPDH plays key roles in cell homeostasis, proliferation, and the immune response, and is the cellular target of several drugs that are widely used for antiviral and immunosuppressive chemotherapy. IMPDH enzyme is tightly regulated at multiple levels, from transcriptional control to allosteric modulation, enzyme filamentation, and posttranslational modifications. Herein, we review recent developments in our understanding of the mechanisms of IMPDH regulation, including all layers of allosteric control that fine‐tune the enzyme activity.
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Affiliation(s)
- Rubén M. Buey
- Metabolic Engineering Group, Department of Microbiology and Genetics Universidad de Salamanca Salamanca Spain
| | - David Fernández‐Justel
- Metabolic Engineering Group, Department of Microbiology and Genetics Universidad de Salamanca Salamanca 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
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21
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Specialization of the photoreceptor transcriptome by Srrm3-dependent microexons is required for outer segment maintenance and vision. Proc Natl Acad Sci U S A 2022; 119:e2117090119. [PMID: 35858306 PMCID: PMC9303857 DOI: 10.1073/pnas.2117090119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Retinal photoreceptors have a distinct transcriptomic profile compared to other neuronal subtypes, likely reflecting their unique cellular morphology and function in the detection of light stimuli by way of the ciliary outer segment. We discovered a layer of this molecular specialization by revealing that the vertebrate retina expresses the largest number of tissue-enriched microexons of all tissue types. A subset of these microexons is included exclusively in photoreceptor transcripts, particularly in genes involved in cilia biogenesis and vesicle-mediated transport. This microexon program is regulated by Srrm3, a paralog of the neural microexon regulator Srrm4. Despite the fact that both proteins positively regulate retina microexons in vitro, only Srrm3 is highly expressed in mature photoreceptors. Its deletion in zebrafish results in widespread down-regulation of microexon inclusion from early developmental stages, followed by other transcriptomic alterations, severe photoreceptor defects, and blindness. These results shed light on the transcriptomic specialization and functionality of photoreceptors, uncovering unique cell type-specific roles for Srrm3 and microexons with implications for retinal diseases.
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22
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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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23
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Wolff DW, Deng Z, Bianchi-Smiraglia A, Foley CE, Han Z, Wang X, Shen S, Rosenberg MM, Moparthy S, Yun DH, Chen J, Baker BK, Roll MV, Magiera AJ, Li J, Hurley E, Feltri ML, Cox AO, Lee J, Furdui CM, Liu L, Bshara W, LaConte LE, Kandel ES, Pasquale EB, Qu J, Hedstrom L, Nikiforov MA. Phosphorylation of guanosine monophosphate reductase triggers a GTP-dependent switch from pro- to anti-oncogenic function of EPHA4. Cell Chem Biol 2022; 29:970-984.e6. [PMID: 35148834 PMCID: PMC9620470 DOI: 10.1016/j.chembiol.2022.01.007] [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: 04/06/2021] [Revised: 11/19/2021] [Accepted: 01/11/2022] [Indexed: 12/11/2022]
Abstract
Signal transduction pathways post-translationally regulating nucleotide metabolism remain largely unknown. Guanosine monophosphate reductase (GMPR) is a nucleotide metabolism enzyme that decreases GTP pools by converting GMP to IMP. We observed that phosphorylation of GMPR at Tyr267 is critical for its activity and found that this phosphorylation by ephrin receptor tyrosine kinase EPHA4 decreases GTP pools in cell protrusions and levels of GTP-bound RAC1. EPHs possess oncogenic and tumor-suppressor activities, although the mechanisms underlying switches between these two modes are poorly understood. We demonstrated that GMPR plays a key role in EPHA4-mediated RAC1 suppression. This supersedes GMPR-independent activation of RAC1 by EPHA4, resulting in a negative overall effect on melanoma cell invasion and tumorigenicity. Accordingly, EPHA4 levels increase during melanoma progression and inversely correlate with GMPR levels in individual melanoma tumors. Therefore, phosphorylation of GMPR at Tyr267 is a metabolic signal transduction switch controlling GTP biosynthesis and transformed phenotypes.
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Affiliation(s)
- David W. Wolff
- Department of Biomedical Engineering, Pratt School of Engineering, Duke University, Durham, NC 27708, USA,Department of Cancer Biology, Wake Forest School of Medicine, Winston Salem, NC 27157, USA
| | - Zhiyong Deng
- Department of Cancer Biology, Wake Forest School of Medicine, Winston Salem, NC 27157, USA
| | - Anna Bianchi-Smiraglia
- Department of Cell Stress Biology, Roswell Park Comprehensive Cancer Center, Buffalo, NY 14203, USA
| | - Colleen E. Foley
- Department of Cell Stress Biology, Roswell Park Comprehensive Cancer Center, Buffalo, NY 14203, USA
| | - Zhannan Han
- Department of Biomedical Engineering, Pratt School of Engineering, Duke University, Durham, NC 27708, USA,Department of Cancer Biology, Wake Forest School of Medicine, Winston Salem, NC 27157, USA
| | - Xingyou Wang
- Department of Chemistry, Brandeis University, Waltham, MA 02453, USA
| | - Shichen Shen
- Department of Pharmaceutical Sciences, University at Buffalo, Buffalo, NY 14214, USA
| | | | - Sudha Moparthy
- Department of Cancer Biology, Wake Forest School of Medicine, Winston Salem, NC 27157, USA
| | - Dong Hyun Yun
- Department of Cancer Biology, Wake Forest School of Medicine, Winston Salem, NC 27157, USA
| | - Jialin Chen
- Department of Biomedical Engineering, Pratt School of Engineering, Duke University, Durham, NC 27708, USA,Department of Cancer Biology, Wake Forest School of Medicine, Winston Salem, NC 27157, USA
| | - Brian K. Baker
- Department of Cancer Biology, Wake Forest School of Medicine, Winston Salem, NC 27157, USA
| | - Matthew V. Roll
- Department of Biomedical Engineering, Pratt School of Engineering, Duke University, Durham, NC 27708, USA,Department of Cancer Biology, Wake Forest School of Medicine, Winston Salem, NC 27157, USA
| | - Andrew J. Magiera
- Department of Cancer Biology, Wake Forest School of Medicine, Winston Salem, NC 27157, USA
| | - Jun Li
- Department of Pharmaceutical Sciences, University at Buffalo, Buffalo, NY 14214, USA
| | - Edward Hurley
- Department of Biochemistry and Neurology, Hunter James Kelly Research Institute, University at Buffalo, Buffalo NY, USA
| | - Maria Laura Feltri
- Department of Biochemistry and Neurology, Hunter James Kelly Research Institute, University at Buffalo, Buffalo NY, USA
| | - Anderson O. Cox
- Department of Internal Medicine, Section of Molecular Medicine, Wake Forest School of Medicine, Winston-Salem NC, USA
| | - Jingyun Lee
- Department of Internal Medicine, Section of Molecular Medicine, Wake Forest School of Medicine, Winston-Salem NC, USA
| | - Cristina M. Furdui
- Department of Internal Medicine, Section of Molecular Medicine, Wake Forest School of Medicine, Winston-Salem NC, USA
| | - Liang Liu
- Department of Cancer Biology, Wake Forest School of Medicine, Winston Salem, NC 27157, USA
| | - Wiam Bshara
- Department of Pathology, Roswell Park Comprehensive Cancer Center, Buffalo NY 14203, USA
| | - Leslie E.W. LaConte
- Fralin Biomedical Research Institute at Virginia Tech Carilion School of Medicine, Roanoke, VA 24016, USA
| | - Eugene S. Kandel
- Department of Cell Stress Biology, Roswell Park Comprehensive Cancer Center, Buffalo, NY 14203, USA
| | - Elena B. Pasquale
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Jun Qu
- Department of Chemistry, Brandeis University, Waltham, MA 02453, USA
| | - Lizbeth Hedstrom
- Department of Chemistry, Brandeis University, Waltham, MA 02453, USA,Department of Biology, Brandeis University, Waltham, MA 02453, USA
| | - Mikhail A. Nikiforov
- Department of Biomedical Engineering, Pratt School of Engineering, Duke University, Durham, NC 27708, USA,Department of Cancer Biology, Wake Forest School of Medicine, Winston Salem, NC 27157, USA,Department of Pathology, Duke University School of Medicine, Durham, NC 27710, USA,Corresponding author and lead contact: Mikhail A. Nikiforov,
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24
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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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25
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Yan J, Günter A, Das S, Mühlfriedel R, Michalakis S, Jiao K, Seeliger MW, Paquet-Durand F. Inherited Retinal Degeneration: PARP-Dependent Activation of Calpain Requires CNG Channel Activity. Biomolecules 2022; 12:biom12030455. [PMID: 35327647 PMCID: PMC8946186 DOI: 10.3390/biom12030455] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 03/08/2022] [Accepted: 03/10/2022] [Indexed: 01/27/2023] Open
Abstract
Inherited retinal degenerations (IRDs) are a group of blinding diseases, typically involving a progressive loss of photoreceptors. The IRD pathology is often based on an accumulation of cGMP in photoreceptors and associated with the excessive activation of calpain and poly (ADP-ribose) polymerase (PARP). Inhibitors of calpain or PARP have shown promise in preventing photoreceptor cell death, yet the relationship between these enzymes remains unclear. To explore this further, organotypic retinal explant cultures derived from wild-type and IRD-mutant mice were treated with inhibitors specific for calpain, PARP, and voltage-gated Ca2+ channels (VGCCs). The outcomes were assessed using in situ activity assays for calpain and PARP and immunostaining for activated calpain-2, poly (ADP-ribose), and cGMP, as well as the TUNEL assay for cell death detection. The IRD models included the Pde6b-mutant rd1 mouse and rd1*Cngb1−/− double-mutant mice, which lack the beta subunit of the rod cyclic nucleotide-gated (CNG) channel and are partially protected from rd1 degeneration. We confirmed that an inhibition of either calpain or PARP reduces photoreceptor cell death in rd1 retina. However, while the activity of calpain was decreased by the inhibition of PARP, calpain inhibition did not alter the PARP activity. A combination treatment with calpain and PARP inhibitors did not synergistically reduce cell death. In the slow degeneration of rd1*Cngb1−/− double mutant, VGCC inhibition delayed photoreceptor cell death, while PARP inhibition did not. Our results indicate that PARP acts upstream of calpain and that both are part of the same degenerative pathway in Pde6b-dependent photoreceptor degeneration. While PARP activation may be associated with CNG channel activity, calpain activation is linked to VGCC opening. Overall, our data highlights PARP as a target for therapeutic interventions in IRD-type diseases.
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Affiliation(s)
- Jie Yan
- Cell Death Mechanism Group, Institute for Ophthalmic Research, University of Tübingen, 72076 Tübingen, Germany; (J.Y.); (S.D.)
- Graduate Training Centre of Neuroscience, University of Tübingen, 72076 Tübingen, Germany
| | - Alexander Günter
- Division of Ocular Neurodegeneration, Institute for Ophthalmic Research, University of Tübingen, 72076 Tübingen, Germany; (A.G.); (R.M.)
| | - Soumyaparna Das
- Cell Death Mechanism Group, Institute for Ophthalmic Research, University of Tübingen, 72076 Tübingen, Germany; (J.Y.); (S.D.)
| | - Regine Mühlfriedel
- Division of Ocular Neurodegeneration, Institute for Ophthalmic Research, University of Tübingen, 72076 Tübingen, Germany; (A.G.); (R.M.)
| | - Stylianos Michalakis
- Department of Ophthalmology, University Hospital, LMU Munich, 80539 München, Germany;
| | - Kangwei Jiao
- Key Laboratory of Yunnan Province, Affiliated Hospital of Yunnan University, Kunming 650051, China;
| | - Mathias W. Seeliger
- Division of Ocular Neurodegeneration, Institute for Ophthalmic Research, University of Tübingen, 72076 Tübingen, Germany; (A.G.); (R.M.)
- Correspondence: (M.W.S.); (F.P.-D.)
| | - François Paquet-Durand
- Cell Death Mechanism Group, Institute for Ophthalmic Research, University of Tübingen, 72076 Tübingen, Germany; (J.Y.); (S.D.)
- Correspondence: (M.W.S.); (F.P.-D.)
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26
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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: 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: 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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27
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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: 17] [Impact Index Per Article: 8.5] [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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28
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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: 2] [Impact Index Per Article: 1.0] [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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29
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Abstract
The outer retina is nourished from the choroid, a capillary bed just inside the sclera. O2, glucose, and other nutrients diffuse out of the choroid and then filter through a monolayer of retinal pigment epithelium (RPE) cells to fuel the retina. Recent studies of energy metabolism have revealed striking differences between retinas and RPE cells in the ways that they extract energy from fuels. The purpose of this review is to suggest and evaluate the hypothesis that the retina and RPE have complementary metabolic roles that make them depend on each other for survival and for their abilities to perform essential and specialized functions. Expected final online publication date for the Annual Review of Vision Science, Volume 7 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- James B Hurley
- Departments of Biochemistry and Ophthalmology, University of Washington, Seattle, Washington 98115, USA;
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30
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Keppeke GD, Chang CC, Antos CL, Peng M, Sung LY, Andrade LEC, Liu JL. IMPDH forms the cytoophidium in zebrafish. Dev Biol 2021; 478:89-101. [PMID: 34048735 DOI: 10.1016/j.ydbio.2021.05.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 05/17/2021] [Accepted: 05/18/2021] [Indexed: 02/07/2023]
Abstract
Inosine monophosphate dehydrogenase (IMPDH) catalyzes the rate-limiting step in de novo guanine nucleotide biosynthesis. Its activity is negatively regulated by the binding of GTP. IMPDH can form a membraneless subcellular structure termed the cytoophidium in response to certain changes in the metabolic status of the cell. The polymeric form of IMPDH, which is the subunit of the cytoophidium, has been shown to be more resistant to the inhibition by GTP at physiological concentrations, implying a functional correlation between cytoophidium formation and the upregulation of GTP biosynthesis. Herein we demonstrate that zebrafish IMPDH1b and IMPDH2 isoforms can assemble abundant cytoophidium in most of cultured cells under stimuli, while zebrafish IMPDH1a shows distinctive properties of forming the cytoophidium in different cell types. Point mutations that disrupt cytoophidium structure in mammalian models also prevent the aggregation of zebrafish IMPDHs. In addition, we discover the presence of the IMPDH cytoophidium in various tissues of larval and adult fish under normal growth conditions. Our results reveal that polymerization and cytoophidium assembly of IMPDH can be a regulatory machinery conserved among vertebrates, and with specific physiological purposes.
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Affiliation(s)
- 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
| | - Chia-Chun Chang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Christopher L Antos
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Min Peng
- Institute of Biotechnology, National Taiwan University, Taipei, 106, Taiwan
| | - Li-Ying Sung
- Institute of Biotechnology, National Taiwan University, Taipei, 106, Taiwan; Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 115, Taiwan
| | - Luis Eduardo Coelho Andrade
- Rheumatology Division, Escola Paulista de Medicina, Universidade Federal de Sao Paulo, Sao Paulo, SP, 04023-062, Brazil
| | - Ji-Long Liu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
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31
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Kofuji S, Sasaki AT. GTP metabolic reprogramming by IMPDH2: unlocking cancer cells' fuelling mechanism. J Biochem 2021; 168:319-328. [PMID: 32702086 DOI: 10.1093/jb/mvaa085] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Accepted: 07/16/2020] [Indexed: 12/15/2022] Open
Abstract
Growing cells increase multiple biosynthetic processes in response to the high metabolic demands needed to sustain proliferation. The even higher metabolic requirements in the setting of cancer provoke proportionately greater biosynthesis. Underappreciated key aspects of this increased metabolic demand are guanine nucleotides and adaptive mechanisms to regulate their concentration. Using the malignant brain tumour, glioblastoma, as a model, we have demonstrated that one of the rate-limiting enzymes for guanosine triphosphate (GTP) synthesis, inosine monophosphate dehydrogenase-2 (IMPDH2), is increased and IMPDH2 expression is necessary for the activation of de novo GTP biosynthesis. Moreover, increased IMPDH2 enhances RNA polymerase I and III transcription directly linking GTP metabolism to both anabolic capacity as well as nucleolar enlargement historically observed as associated with cancer. In this review, we will review in detail the basis of these new discoveries and, more generally, summarize the current knowledge on the role of GTP metabolism in cancer.
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Affiliation(s)
- Satoshi Kofuji
- Department of Developmental and Regenerative Biology, Medical Research Institute, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Atsuo T Sasaki
- Division of Hematology and Oncology, Department of Internal Medicine, University of Cincinnati College of Medicine, 3125 Eden Ave., Cincinnati, OH 45267-0508, USA.,Department of Cancer Biology, University of Cincinnati College of Medicine, 3125 Eden Ave., OH 45267-0508, USA.,Department of Neurosurgery, Brain Tumor Center at UC Gardner Neuroscience Institute, 3113 Bellevue Ave, Cincinnati, OH 45267-0508, USA.,Institute for Advanced Biosciences, Keio University, Kakuganji 246-2, Mizukami, Tsuruoka City, Yamagata 997-0052, Japan
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32
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Photoreceptor metabolic reprogramming: current understanding and therapeutic implications. Commun Biol 2021; 4:245. [PMID: 33627778 PMCID: PMC7904922 DOI: 10.1038/s42003-021-01765-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 01/28/2021] [Indexed: 02/06/2023] Open
Abstract
Acquired and inherited retinal disorders are responsible for vision loss in an increasing proportion of individuals worldwide. Photoreceptor (PR) death is central to the vision loss individuals experience in these various retinal diseases. Unfortunately, there is a lack of treatment options to prevent PR loss, so an urgent unmet need exists for therapies that improve PR survival and ultimately, vision. The retina is one of the most energy demanding tissues in the body, and this is driven in large part by the metabolic needs of PRs. Recent studies suggest that disruption of nutrient availability and regulation of cell metabolism may be a unifying mechanism in PR death. Understanding retinal cell metabolism and how it is altered in disease has been identified as a priority area of research. The focus of this review is on the recent advances in the understanding of PR metabolism and how it is critical to reduction-oxidation (redox) balance, the outer retinal metabolic ecosystem, and retinal disease. The importance of these metabolic processes is just beginning to be realized and unraveling the metabolic and redox pathways integral to PR health may identify novel targets for neuroprotective strategies that prevent blindness in the heterogenous group of retinal disorders.
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33
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Zhang R, Engel AL, Wang Y, Li B, Shen W, Gillies MC, Chao JR, Du J. Inhibition of Mitochondrial Respiration Impairs Nutrient Consumption and Metabolite Transport in Human Retinal Pigment Epithelium. J Proteome Res 2020; 20:909-922. [PMID: 32975122 DOI: 10.1021/acs.jproteome.0c00690] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Mitochondrial respiration in mammalian cells not only generates ATP to meet their own energy needs but also couples with biosynthetic pathways to produce metabolites that can be exported to support neighboring cells. However, how defects in mitochondrial respiration influence these biosynthetic and exporting pathways remains poorly understood. Mitochondrial dysfunction in retinal pigment epithelium (RPE) cells is an emerging contributor to the death of their neighboring photoreceptors in degenerative retinal diseases including age-related macular degeneration. In this study, we used targeted-metabolomics and 13C tracing to investigate how inhibition of mitochondrial respiration influences the intracellular and extracellular metabolome. We found inhibition of mitochondrial respiration strikingly influenced both the intracellular and extracellular metabolome in primary RPE cells. Intriguingly, the extracellular metabolic changes sensitively reflected the intracellular changes. These changes included substantially enhanced glucose consumption and lactate production; reduced release of pyruvate, citrate, and ketone bodies; and massive accumulation of multiple amino acids and nucleosides. In conclusion, these findings reveal a metabolic signature of nutrient consumption and release in mitochondrial dysfunction in RPE cells. Testing medium metabolites provides a sensitive and noninvasive method to assess mitochondrial function in nutrient utilization and transport.
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Affiliation(s)
- Rui Zhang
- Department of Ophthalmology, West Virginia University, Morgantown, West Virginia 26506, United States.,Department of Biochemistry, West Virginia University, Morgantown, West Virginia 26506, United States.,Save Sight Institute, Sydney Medical School, University of Sydney, Sydney, NSW 2000, Australia
| | - Abbi L Engel
- Department of Ophthalmology, University of Washington, Seattle, Washington 98109, United States
| | - Yekai Wang
- Department of Ophthalmology, West Virginia University, Morgantown, West Virginia 26506, United States.,Department of Biochemistry, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Bo Li
- Department of Ophthalmology, West Virginia University, Morgantown, West Virginia 26506, United States.,Department of Biochemistry, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Weiyong Shen
- Save Sight Institute, Sydney Medical School, University of Sydney, Sydney, NSW 2000, Australia
| | - Mark C Gillies
- Save Sight Institute, Sydney Medical School, University of Sydney, Sydney, NSW 2000, Australia
| | - Jennifer R Chao
- Department of Ophthalmology, University of Washington, Seattle, Washington 98109, United States
| | - Jianhai Du
- Department of Ophthalmology, West Virginia University, Morgantown, West Virginia 26506, United States.,Department of Biochemistry, West Virginia University, Morgantown, West Virginia 26506, United States
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34
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Keppeke GD, Andrade LEC, Barcelos D, Fernandes M, Landman G. IMPDH-Based Cytoophidium Structures as Potential Theranostics in Cancer. Mol Ther 2020; 28:1557-1558. [PMID: 32534605 DOI: 10.1016/j.ymthe.2020.06.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Affiliation(s)
- Gerson Dierley Keppeke
- Rheumatology Division, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil.
| | | | - Denise Barcelos
- Department of Pathology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Mariana Fernandes
- Department of Pathology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Gilles Landman
- Department of Pathology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
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