1
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Mastrangelo M, Manti F, Ricciardi G, Cinnante EMC, Cameli N, Beatrice A, Tolve M, Pisani F. The diagnostic and prognostic role of cerebrospinal fluid biomarkers in glucose transporter 1 deficiency: a systematic review. Eur J Pediatr 2024; 183:3665-3678. [PMID: 38954008 PMCID: PMC11322378 DOI: 10.1007/s00431-024-05657-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 06/13/2024] [Accepted: 06/17/2024] [Indexed: 07/04/2024]
Abstract
The purpose of this study is to investigate the diagnostic and prognostic role of cerebrospinal fluid (CSF) biomarkers in the diagnostic work-up of glucose transporter 1 (GLUT1) deficiency. Reported here is a systematic review according to PRISMA guidelines collecting clinical and biochemical data about all published patients who underwent CSF analysis. Clinical phenotypes were compared between groups defined by the levels of CSF glucose (≤ 2.2 mmol/L versus > 2.2 mmol/L), CSF/blood glucose ratio (≤ 0.45 versus > 0.45), and CSF lactate (≤ 1 mmol/L versus > 1 mmol/L). Five hundred sixty-two patients fulfilled the inclusion criteria with a mean age at the diagnosis of 8.6 ± 6.7 years. Patients with CSF glucose ≤ 2.2 mmol/L and CSF/blood glucose ratio ≤ 0.45 presented with an earlier onset of symptoms (16.4 ± 22.0 versus 54.4 ± 45.9 months, p < 0.01; 15.7 ± 23.8 versus 40.9 ± 38.0 months, p < 0.01) and received an earlier molecular genetic confirmation (92.1 ± 72.8 versus 157.1 ± 106.2 months, p < 0.01). CSF glucose ≤ 2.2 mmol/L was consistently associated with response to ketogenic diet (p = 0.018) and antiseizure medications (p = 0.025). CSF/blood glucose ratio ≤ 0.45 was significantly associated with absence seizures (p = 0.048), paroxysmal exercise-induced dyskinesia (p = 0.046), and intellectual disability (p = 0.016) while CSF lactate > 1 mmol/L was associated with a response to antiseizure medications (p = 0.026) but not to ketogenic diet.Conclusions:This systematic review supported the diagnostic usefulness of lumbar puncture for the early identification of patients with GLUT1 deficiency responsive to treatments especially if they present with co-occurring epilepsy, movement, and neurodevelopmental disorders. What is Known: • Phenotypes of GLUT1 deficiency syndrome range between early epileptic and developmental encephalopathy to paroxysmal movement disorders and developmental impairment What is New: • CSF blood/glucose ratio may predict better than CSF glucose the diagnosis in children presenting with early onset absences • CSF blood/glucose ratio may predict better than CSF glucose the diagnosis in children presenting with paroxysmal exercise induced dyskinesia and intellectual disability. • CSF glucose may predict better than CSF blood/glucose and lactate the response to ketogenic diet and antiseizure medications.
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Affiliation(s)
- Mario Mastrangelo
- Woman/Child Health and Urological Sciences Department, Sapienza University of Rome, Via dei Sabelli 108, 00185, Rome, Italy.
- Unit of Child Neurology and Psychiatry, Department of Neuroscience/Mental Health, Azienda Ospedaliero Universitaria Policlinico Umberto, Rome, Italy.
| | - Filippo Manti
- Unit of Child Neurology and Psychiatry, Department of Neuroscience/Mental Health, Azienda Ospedaliero Universitaria Policlinico Umberto, Rome, Italy
- Department of Human Neuroscience, Sapienza University of Rome, Rome, Italy
| | | | | | - Noemi Cameli
- Department of Human Neuroscience, Sapienza University of Rome, Rome, Italy
| | | | - Manuela Tolve
- Clinical Pathology Unit, Azienda Ospedaliero-Universitaria Policlinico Umberto I, Rome, Italy
| | - Francesco Pisani
- Unit of Child Neurology and Psychiatry, Department of Neuroscience/Mental Health, Azienda Ospedaliero Universitaria Policlinico Umberto, Rome, Italy
- Department of Human Neuroscience, Sapienza University of Rome, Rome, Italy
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2
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Klip A, De Bock K, Bilan PJ, Richter EA. Transcellular Barriers to Glucose Delivery in the Body. Annu Rev Physiol 2024; 86:149-173. [PMID: 38345907 DOI: 10.1146/annurev-physiol-042022-031657] [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] [Indexed: 02/15/2024]
Abstract
Glucose is the universal fuel of most mammalian cells, and it is largely replenished through dietary intake. Glucose availability to tissues is paramount for the maintenance of homeostatic energetics and, hence, supply should match demand by the consuming organs. In its journey through the body, glucose encounters cellular barriers for transit at the levels of the absorbing intestinal epithelial wall, the renal epithelium mediating glucose reabsorption, and the tight capillary endothelia (especially in the brain). Glucose transiting through these cellular barriers must escape degradation to ensure optimal glucose delivery to the bloodstream or tissues. The liver, which stores glycogen and generates glucose de novo, must similarly be able to release it intact to the circulation. We present the most up-to-date knowledge on glucose handling by the gut, liver, brain endothelium, and kidney, and discuss underlying molecular mechanisms and open questions. Diseases associated with defects in glucose delivery and homeostasis are also briefly addressed. We propose that the universal problem of sparing glucose from catabolism in favor of translocation across the barriers posed by epithelia and endothelia is resolved through common mechanisms involving glucose transfer to the endoplasmic reticulum, from where glucose exits the cells via unconventional cellular mechanisms.
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Affiliation(s)
- Amira Klip
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada;
| | - Katrien De Bock
- Laboratory of Exercise and Health, Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH), Zürich, Switzerland
| | - Philip J Bilan
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada;
| | - Erik A Richter
- The August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
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3
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Tayebi N, Leon‐Ricardo B, McCall K, Mehinovic E, Engelstad K, Huynh V, Turner TN, Weisenberg J, Thio LL, Hruz P, Williams RSB, De Vivo DC, Petit V, Haller G, Gurnett CA. Quantitative determination of SLC2A1 variant functional effects in GLUT1 deficiency syndrome. Ann Clin Transl Neurol 2023; 10:787-801. [PMID: 37000947 PMCID: PMC10187726 DOI: 10.1002/acn3.51767] [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: 11/30/2022] [Revised: 03/08/2023] [Accepted: 03/12/2023] [Indexed: 04/03/2023] Open
Abstract
OBJECTIVE The goal of this study is to demonstrate the utility of a growth assay to quantify the functional impact of single nucleotide variants (SNVs) in SLC2A1, the gene responsible for Glut1DS. METHODS The functional impact of 40 SNVs in SLC2A1 was quantitatively determined in HAP1 cells in which SLC2A1 is required for growth. Donor libraries were introduced into the endogenous SLC2A1 gene in HAP1-Lig4KO cells using CRISPR/Cas9. Cell populations were harvested and sequenced to quantify the effect of variants on growth and generate a functional score. Quantitative functional scores were compared to 3-OMG uptake, SLC2A1 cell surface expression, CADD score, and clinical data, including CSF/blood glucose ratio. RESULTS Nonsense variants (N = 3) were reduced in cell culture over time resulting in negative scores (mean score: -1.15 ± 0.17), whereas synonymous variants (N = 10) were not depleted (mean score: 0.25 ± 0.12) (P < 2e-16). Missense variants (N = 27) yielded a range of functional scores including slightly negative scores, supporting a partial function and intermediate phenotype. Several variants with normal results on either cell surface expression (p.N34S and p.W65R) or 3-OMG uptake (p.W65R) had negative functional scores. There is a moderate but significant correlation between our functional scores and CADD scores. INTERPRETATION Cell growth is useful to quantitatively determine the functional effects of SLC2A1 variants. Nonsense variants were reliably distinguished from benign variants in this in vitro functional assay. For facilitating early diagnosis and therapeutic intervention, future work is needed to determine the functional effect of every possible variant in SLC2A1.
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Affiliation(s)
- Naeimeh Tayebi
- Department of NeurologyWashington University in St LouisSt LouisMissouriUSA
| | - Brian Leon‐Ricardo
- Department of NeurologyWashington University in St LouisSt LouisMissouriUSA
| | - Kevin McCall
- Department of NeurologyWashington University in St LouisSt LouisMissouriUSA
| | - Elvisa Mehinovic
- Department of GeneticsWashington University in St LouisSt LouisMissouriUSA
| | - Kristin Engelstad
- Department of NeurologyColumbia University Irving Medical CenterNew YorkNew YorkUSA
| | - Vincent Huynh
- Department of NeurologyColumbia University Irving Medical CenterNew YorkNew YorkUSA
| | - Tychele N. Turner
- Department of GeneticsWashington University in St LouisSt LouisMissouriUSA
| | - Judy Weisenberg
- Department of NeurologyWashington University in St LouisSt LouisMissouriUSA
| | - Liu L. Thio
- Department of NeurologyWashington University in St LouisSt LouisMissouriUSA
| | - Paul Hruz
- Department of PediatricsWashington University in St LouisSt LouisMissouriUSA
| | - Robin S. B. Williams
- Centre for Biomedical Sciences, Department of Biological SciencesRoyal Holloway University of LondonEghamUK
| | - Darryl C. De Vivo
- Department of NeurologyColumbia University Irving Medical CenterNew YorkNew YorkUSA
| | | | - Gabe Haller
- Department of NeurologyWashington University in St LouisSt LouisMissouriUSA
- Department of GeneticsWashington University in St LouisSt LouisMissouriUSA
- Department of Neurological SurgeryWashington University in St LouisSt LouisMissouriUSA
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4
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Wang RC, Lee EE, De Simone N, Kathote G, Primeaux S, Avila A, Yu DM, Johnson M, Good LB, Jakkamsetti V, Sarode R, Holland AA, Pascual JM. Red blood cells as glucose carriers to the human brain: Modulation of cerebral activity by erythrocyte exchange transfusion in Glut1 deficiency (G1D). J Cereb Blood Flow Metab 2023; 43:357-368. [PMID: 36523131 PMCID: PMC9941860 DOI: 10.1177/0271678x221146121] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 11/08/2022] [Accepted: 11/14/2022] [Indexed: 12/23/2022]
Abstract
Red blood cells circulating through the brain are briefly but closely apposed to the capillary endothelium. We hypothesized that this contact provides a nearly direct pathway for metabolic substrate transfer to neural cells that complements the better characterized plasma to endothelium transfer. While brain function is considered independent of normal fluctuations in blood glucose concentration, this is not borne out by persons with glucose transporter I (GLUT1) deficiency (G1D). In them, encephalopathy is often ameliorated by meal or carbohydrate administration, and this enabled us to test our hypothesis: Since red blood cells contain glucose, and since the red cells of G1D individuals are also deficient in GLUT1, replacing them with normal donor cells via exchange transfusion could augment erythrocyte to neural cell glucose transport via mass action in the setting of unaltered erythrocyte count or plasma glucose abundance. This motivated us to perform red blood cell exchange in 3 G1D persons. There were rapid, favorable and unprecedented changes in cognitive, electroencephalographic and quality-of-life measures. The hypothesized transfer mechanism was further substantiated by in vitro measurement of direct erythrocyte to endothelial cell glucose flux. The results also indicate that the adult intellect is capable of significant enhancement without deliberate practice. ClinicalTrials.gov registration: NCT04137692 https://clinicaltrials.gov/ct2/show/NCT04137692.
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Affiliation(s)
- Richard C Wang
- Department of Dermatology, The University of Texas Southwestern
Medical Center, Dallas, Texas, USA
| | - Eunice E Lee
- Department of Dermatology, The University of Texas Southwestern
Medical Center, Dallas, Texas, USA
| | - Nicole De Simone
- Department of Pathology, The University of Texas Southwestern
Medical Center, Dallas, Texas, USA
| | - Gauri Kathote
- Rare Brain Disorders Program, The University of Texas
Southwestern Medical Center, Dallas, Texas, USA
- Department of Neurology, The University of Texas Southwestern
Medical Center, Dallas, Texas, USA
| | - Sharon Primeaux
- Rare Brain Disorders Program, The University of Texas
Southwestern Medical Center, Dallas, Texas, USA
- Department of Neurology, The University of Texas Southwestern
Medical Center, Dallas, Texas, USA
| | - Adrian Avila
- Rare Brain Disorders Program, The University of Texas
Southwestern Medical Center, Dallas, Texas, USA
- Department of Neurology, The University of Texas Southwestern
Medical Center, Dallas, Texas, USA
| | - Dong-Min Yu
- Department of Dermatology, The University of Texas Southwestern
Medical Center, Dallas, Texas, USA
| | - Mark Johnson
- Department of Neurology, The University of Texas Southwestern
Medical Center, Dallas, Texas, USA
| | - Levi B Good
- Rare Brain Disorders Program, The University of Texas
Southwestern Medical Center, Dallas, Texas, USA
- Department of Neurology, The University of Texas Southwestern
Medical Center, Dallas, Texas, USA
| | - Vikram Jakkamsetti
- Rare Brain Disorders Program, The University of Texas
Southwestern Medical Center, Dallas, Texas, USA
- Department of Neurology, The University of Texas Southwestern
Medical Center, Dallas, Texas, USA
| | - Ravi Sarode
- Departments of Pathology and Internal Medicine, The University
of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Alice Ann Holland
- Department of Psychiatry, The University of Texas Southwestern
Medical Center, Dallas, Texas, USA
| | - Juan M Pascual
- Rare Brain Disorders Program, The University of Texas
Southwestern Medical Center, Dallas, Texas, USA
- Department of Neurology, The University of Texas Southwestern
Medical Center, Dallas, Texas, USA
- Department of Physiology, The University of Texas Southwestern
Medical Center, Dallas, Texas, USA
- Department of Pediatrics, The University of Texas Southwestern
Medical Center, Dallas, Texas, USA
- Eugene McDermott Center for Human Growth &
Development/Center for Human Genetics, The University of Texas Southwestern
Medical Center, Dallas, Texas, USA
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5
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Mauri A, Duse A, Palm G, Previtali R, Bova SM, Olivotto S, Benedetti S, Coscia F, Veggiotti P, Cereda C. Molecular Genetics of GLUT1DS Italian Pediatric Cohort: 10 Novel Disease-Related Variants and Structural Analysis. Int J Mol Sci 2022; 23:ijms232113560. [PMID: 36362347 PMCID: PMC9654628 DOI: 10.3390/ijms232113560] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 10/26/2022] [Accepted: 10/29/2022] [Indexed: 11/09/2022] Open
Abstract
GLUT1 deficiency syndrome (GLUT1DS1; OMIM #606777) is a rare genetic metabolic disease, characterized by infantile-onset epileptic encephalopathy, global developmental delay, progressive microcephaly, and movement disorders (e.g., spasticity and dystonia). It is caused by heterozygous mutations in the SLC2A1 gene, which encodes the GLUT1 protein, a glucose transporter across the blood-brain barrier (BBB). Most commonly, these variants arise de novo resulting in sporadic cases, although several familial cases with AD inheritance pattern have been described. Twenty-seven Italian pediatric patients, clinically suspect of GLUT1DS from both sporadic and familial cases, have been enrolled. We detected by trios sequencing analysis 25 different variants causing GLUT1DS. Of these, 40% of the identified variants (10 out of 25) had never been reported before, including missense, frameshift, and splice site variants. Their structural mapping on the X-ray structure of GLUT1 strongly suggested the potential pathogenic effects of these novel disease-related mutations, broadening the genotypic spectrum heterogeneity found in the SLC2A1 gene. Moreover, 24% is located in a vulnerable region of the GLUT1 protein that involves transmembrane 4 and 5 helices encoded by exon 4, confirming a mutational hotspot in the SLC2A1 gene. Lastly, we investigated possible correlations between mutation type and clinical and biochemical data observed in our GLUT1DS cohort, revealing that splice site and frameshift variants are related to a more severe phenotype and low CSF parameters.
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Affiliation(s)
- Alessia Mauri
- Department of Biomedical and Clinical Sciences, University of Milan, 20157 Milan, Italy
- Newborn Screening and Genetic Metabolic Diseases Unit, V. Buzzi Children’s Hospital, 20154 Milan, Italy
| | - Alessandra Duse
- Pediatric Neurology Unit, V. Buzzi Children’s Hospital, 20154 Milan, Italy
| | - Giacomo Palm
- Structural Biology Center, Human Technopole, 20157 Milan, Italy
| | - Roberto Previtali
- Pediatric Neurology Unit, V. Buzzi Children’s Hospital, 20154 Milan, Italy
| | | | - Sara Olivotto
- Pediatric Neurology Unit, V. Buzzi Children’s Hospital, 20154 Milan, Italy
| | - Sara Benedetti
- Newborn Screening and Genetic Metabolic Diseases Unit, V. Buzzi Children’s Hospital, 20154 Milan, Italy
| | | | - Pierangelo Veggiotti
- Department of Biomedical and Clinical Sciences, University of Milan, 20157 Milan, Italy
- Pediatric Neurology Unit, V. Buzzi Children’s Hospital, 20154 Milan, Italy
| | - Cristina Cereda
- Newborn Screening and Genetic Metabolic Diseases Unit, V. Buzzi Children’s Hospital, 20154 Milan, Italy
- Correspondence:
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6
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Rojas SAT, Boles E, Oreb M. A yeast-based in vivo assay system for analyzing efflux of sugars mediated by glucose and xylose transporters. FEMS Yeast Res 2022; 21:6653521. [PMID: 35918180 DOI: 10.1093/femsyr/foac038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 07/14/2022] [Accepted: 07/29/2022] [Indexed: 11/13/2022] Open
Abstract
Sugar transporter research focuses on the sugar uptake into cells. Under certain physiological conditions, however, the intracellular accumulation and secretion of carbohydrates (efflux) are relevant processes in many cell types. Currently, no cell-based system is available for specifically investigating glucose efflux. Therefore, we designed a system based on a hexose transporter-deficient Saccharomyces cerevisiae strain, in which the disaccharide maltose is provided as a donor of intracellular glucose. By deleting the hexokinase genes, we prevented the metabolization of glucose and thereby achieved the accumulation of growth-inhibitory glucose levels inside the cells. When a permease mediating glucose efflux is expressed in this system, the inhibitory effect is relieved proportionally to the capacity of the introduced transporter. The assay is thereby suitable for screening of transporters and quantitative analyses of their glucose efflux capacities. Moreover, by simultaneous provision of intracellular glucose and extracellular xylose, we investigated how each sugar influences the transport of the other one from the opposite side of the membrane. Thereby, we could show that the xylose transporter variant Gal2N376F is insensitive not only to extracellular but also to intracellular glucose. Considering the importance of sugar transporters in biotechnology, the assay could facilitate new developments in a variety of applications.
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Affiliation(s)
- Sebastian A Tamayo Rojas
- Institute of Molecular Biosciences, Faculty of Biological Sciences, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Eckhard Boles
- Institute of Molecular Biosciences, Faculty of Biological Sciences, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Mislav Oreb
- Institute of Molecular Biosciences, Faculty of Biological Sciences, Goethe University Frankfurt, Frankfurt am Main, Germany
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7
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Drew D, North RA, Nagarathinam K, Tanabe M. Structures and General Transport Mechanisms by the Major Facilitator Superfamily (MFS). Chem Rev 2021; 121:5289-5335. [PMID: 33886296 PMCID: PMC8154325 DOI: 10.1021/acs.chemrev.0c00983] [Citation(s) in RCA: 168] [Impact Index Per Article: 56.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Indexed: 12/12/2022]
Abstract
The major facilitator superfamily (MFS) is the largest known superfamily of secondary active transporters. MFS transporters are responsible for transporting a broad spectrum of substrates, either down their concentration gradient or uphill using the energy stored in the electrochemical gradients. Over the last 10 years, more than a hundred different MFS transporter structures covering close to 40 members have provided an atomic framework for piecing together the molecular basis of their transport cycles. Here, we summarize the remarkable promiscuity of MFS members in terms of substrate recognition and proton coupling as well as the intricate gating mechanisms undergone in achieving substrate translocation. We outline studies that show how residues far from the substrate binding site can be just as important for fine-tuning substrate recognition and specificity as those residues directly coordinating the substrate, and how a number of MFS transporters have evolved to form unique complexes with chaperone and signaling functions. Through a deeper mechanistic description of glucose (GLUT) transporters and multidrug resistance (MDR) antiporters, we outline novel refinements to the rocker-switch alternating-access model, such as a latch mechanism for proton-coupled monosaccharide transport. We emphasize that a full understanding of transport requires an elucidation of MFS transporter dynamics, energy landscapes, and the determination of how rate transitions are modulated by lipids.
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Affiliation(s)
- David Drew
- Department
of Biochemistry and Biophysics, Stockholm
University, SE 106 91 Stockholm, Sweden
| | - Rachel A. North
- Department
of Biochemistry and Biophysics, Stockholm
University, SE 106 91 Stockholm, Sweden
| | - Kumar Nagarathinam
- Center
of Structural and Cell Biology in Medicine, Institute of Biochemistry, University of Lübeck, D-23538, Lübeck, Germany
| | - Mikio Tanabe
- Structural
Biology Research Center, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Oho 1-1, Tsukuba, Ibaraki 305-0801, Japan
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8
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Holman GD. Structure, function and regulation of mammalian glucose transporters of the SLC2 family. Pflugers Arch 2020; 472:1155-1175. [PMID: 32591905 PMCID: PMC7462842 DOI: 10.1007/s00424-020-02411-3] [Citation(s) in RCA: 103] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 05/27/2020] [Accepted: 05/29/2020] [Indexed: 12/12/2022]
Abstract
The SLC2 genes code for a family of GLUT proteins that are part of the major facilitator superfamily (MFS) of membrane transporters. Crystal structures have recently revealed how the unique protein fold of these proteins enables the catalysis of transport. The proteins have 12 transmembrane spans built from a replicated trimer substructure. This enables 4 trimer substructures to move relative to each other, and thereby alternately opening and closing a cleft to either the internal or the external side of the membrane. The physiological substrate for the GLUTs is usually a hexose but substrates for GLUTs can include urate, dehydro-ascorbate and myo-inositol. The GLUT proteins have varied physiological functions that are related to their principal substrates, the cell type in which the GLUTs are expressed and the extent to which the proteins are associated with subcellular compartments. Some of the GLUT proteins translocate between subcellular compartments and this facilitates the control of their function over long- and short-time scales. The control of GLUT function is necessary for a regulated supply of metabolites (mainly glucose) to tissues. Pathophysiological abnormalities in GLUT proteins are responsible for, or associated with, clinical problems including type 2 diabetes and cancer and a range of tissue disorders, related to tissue-specific GLUT protein profiles. The availability of GLUT crystal structures has facilitated the search for inhibitors and substrates and that are specific for each GLUT and that can be used therapeutically. Recent studies are starting to unravel the drug targetable properties of each of the GLUT proteins.
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Affiliation(s)
- Geoffrey D Holman
- Department of Biology and Biochemistry, University of Bath, Bath, BA2 7AY, UK.
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9
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Chemical biology probes of mammalian GLUT structure and function. Biochem J 2018; 475:3511-3534. [PMID: 30459202 PMCID: PMC6243331 DOI: 10.1042/bcj20170677] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 10/11/2018] [Accepted: 10/11/2018] [Indexed: 12/14/2022]
Abstract
The structure and function of glucose transporters of the mammalian GLUT family of proteins has been studied over many decades, and the proteins have fascinated numerous research groups over this time. This interest is related to the importance of the GLUTs as archetypical membrane transport facilitators, as key limiters of the supply of glucose to cell metabolism, as targets of cell insulin and exercise signalling and of regulated membrane traffic, and as potential drug targets to combat cancer and metabolic diseases such as type 2 diabetes and obesity. This review focusses on the use of chemical biology approaches and sugar analogue probes to study these important proteins.
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10
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Naftalin RJ. A critique of the alternating access transporter model of uniport glucose transport. BIOPHYSICS REPORTS 2018; 4:287-299. [PMID: 30596138 PMCID: PMC6276071 DOI: 10.1007/s41048-018-0076-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 07/20/2018] [Indexed: 12/16/2022] Open
Affiliation(s)
- Richard J Naftalin
- Physiology and Vascular Biology Group, King's College London Medical School, Waterloo Campus, London, SE1 9HN UK
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11
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Nationwide survey of glucose transporter-1 deficiency syndrome (GLUT-1DS) in Japan. Brain Dev 2015; 37:780-9. [PMID: 25487684 DOI: 10.1016/j.braindev.2014.11.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Revised: 10/20/2014] [Accepted: 11/20/2014] [Indexed: 11/22/2022]
Abstract
OBJECTIVES We conducted a nationwide survey of glucose transporter type-1 deficiency syndrome (GLUT-1DS) in Japan in order to clarify its incidence as well as clinical and laboratory information. SUBJECTS AND METHODS A questionnaire to survey the number of genetically and clinically confirmed cases of GLUT-1DS was sent to 1018 board-certified pediatric neurologists, which resulted in 57 patients being reported. We obtained the clinical and laboratory data of 33 patients through a secondary questionnaire. RESULTS The age of the 33 patients (male: 15, female: 18) at the time of the study ranged between 3 and 35 years (mean: 13.5 years). The age of these patients at the onset of initial neurological symptoms ranged between the neonatal period and 48 months (mean: 9.4 months). GLUT-1DS was diagnosed at a mean age of 8.4 years (range: 1 year to 33 years). The initial symptom was convulsive seizures, which occurred in 15 cases, and was followed by abnormal eye movements in 7 cases and apneic or cyanotic attacks in 4 cases. The latter two symptoms most frequently occurred early in infancy. Thirty-two patients (97%) exhibited some type of epileptic seizure. Neurological findings revealed that most patients had muscle hypotonia, cerebellar ataxia, dystonia, and spastic paralysis. Mild to severe mental retardation was detected in all 33 cases. Furthermore, paroxysmal episodes of ataxia, dystonia/dyskinesia, and motor paralysis were described in approximately 1/3 of all patients. The factors that frequently aggravated these events were hunger, exercise, fever, and fatigue, in that order. The mean CSF/blood glucose ratio was 0.36 (0.28-0.48). Pathological mutations in the SLC2A1 gene were identified in 28 out of 32 cases (87.5%). CONCLUSION The results described herein provided an insight into the early diagnosis of GLUT1-DS, including unexplained paroxysmal abnormal eye movements, apneic/cyanotic attacks, and convulsive seizures in infancy, as well as uncommon paroxysmal events (ataxia, atonia, and motor paralysis) in childhood.
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12
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Lee EE, Ma J, Sacharidou A, Mi W, Salato VK, Nguyen N, Jiang Y, Pascual JM, North PE, Shaul PW, Mettlen M, Wang RC. A Protein Kinase C Phosphorylation Motif in GLUT1 Affects Glucose Transport and is Mutated in GLUT1 Deficiency Syndrome. Mol Cell 2015; 58:845-53. [PMID: 25982116 DOI: 10.1016/j.molcel.2015.04.015] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Revised: 03/09/2015] [Accepted: 04/07/2015] [Indexed: 12/31/2022]
Abstract
Protein kinase C has been implicated in the phosphorylation of the erythrocyte/brain glucose transporter, GLUT1, without a clear understanding of the site(s) of phosphorylation and the possible effects on glucose transport. Through in vitro kinase assays, mass spectrometry, and phosphospecific antibodies, we identify serine 226 in GLUT1 as a PKC phosphorylation site. Phosphorylation of S226 is required for the rapid increase in glucose uptake and enhanced cell surface localization of GLUT1 induced by the phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Endogenous GLUT1 is phosphorylated on S226 in primary endothelial cells in response to TPA or VEGF. Several naturally occurring, pathogenic mutations that cause GLUT1 deficiency syndrome disrupt this PKC phosphomotif, impair the phosphorylation of S226 in vitro, and block TPA-mediated increases in glucose uptake. We demonstrate that the phosphorylation of GLUT1 on S226 regulates glucose transport and propose that this modification is important in the physiological regulation of glucose transport.
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Affiliation(s)
- Eunice E Lee
- Department of Dermatology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jing Ma
- Department of Dermatology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | | | - Wentao Mi
- Department of Neurology and Neurotherapeutics, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Valerie K Salato
- Department of Pathology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Nam Nguyen
- Department of Physiology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Youxing Jiang
- Department of Physiology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Juan M Pascual
- Department of Pediatrics, UT Southwestern Medical Center, Dallas, TX 75390, USA; Department of Neurology and Neurotherapeutics, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Paula E North
- Department of Pathology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Philip W Shaul
- Department of Pediatrics, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Marcel Mettlen
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Richard C Wang
- Department of Dermatology, UT Southwestern Medical Center, Dallas, TX 75390, USA.
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13
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Park MS. Molecular Dynamics Simulations of the Human Glucose Transporter GLUT1. PLoS One 2015; 10:e0125361. [PMID: 25919356 PMCID: PMC4412407 DOI: 10.1371/journal.pone.0125361] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 03/12/2015] [Indexed: 01/31/2023] Open
Abstract
Glucose transporters (GLUTs) provide a pathway for glucose transport across membranes. Human GLUTs are implicated in devastating diseases such as heart disease, hyper- and hypo-glycemia, type 2 diabetes and cancer. The human GLUT1 has been recently crystalized in the inward-facing open conformation. However, there is no other structural information for other conformations. The X-ray structures of E. coli Xylose permease (XylE), a glucose transporter homolog, are available in multiple conformations with and without the substrates D-xylose and D-glucose. XylE has high sequence homology to human GLUT1 and key residues in the sugar-binding pocket are conserved. Here we construct a homology model for human GLUT1 based on the available XylE crystal structure in the partially occluded outward-facing conformation. A long unbiased all atom molecular dynamics simulation starting from the model can capture a new fully opened outward-facing conformation. Our investigation of molecular interactions at the interface between the transmembrane (TM) domains and the intracellular helices (ICH) domain in the outward- and inward-facing conformation supports that the ICH domain likely stabilizes the outward-facing conformation in GLUT1. Furthermore, inducing a conformational transition, our simulations manifest a global asymmetric rocker switch motion and detailed molecular interactions between the substrate and residues through the water-filled selective pore along a pathway from the extracellular to the intracellular side. The results presented here are consistent with previously published biochemical, mutagenesis and functional studies. Together, this study shed light on the structure and functional relationships of GLUT1 in multiple conformational states.
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Affiliation(s)
- Min-Sun Park
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia, United States of America
- * E-mail:
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14
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Cunningham P, Naftalin RJ. Reptation-induced coalescence of tunnels and cavities in Escherichia Coli XylE transporter conformers accounts for facilitated diffusion. J Membr Biol 2014; 247:1161-79. [PMID: 25163893 PMCID: PMC4207944 DOI: 10.1007/s00232-014-9711-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Accepted: 07/15/2014] [Indexed: 11/30/2022]
Abstract
Structural changes and xylose docking to eight conformers of Escherichia Coli XylE, a xylose transporter similar to mammalian passive glucose transporters GLUTs, have been examined. Xylose docks to inward and outward facing conformers at a high affinity central site (Ki 4–20 µM), previously identified by crystallography and additionally consistently docks to lower affinity sites in the external and internal vestibules (Ki 12–50 µM). All these sites lie within intramolecular tunnels and cavities. Several local regions in the central transmembrane zone have large positional divergences of both skeleton carbon Cα positions and side chains. One such in TM 10 is the destabilizing sequence G388-P389-V390-C391 with an average RMSD (4.5 ± 0.4 Å). Interchange between conformer poses results in coalescence of tunnels with adjacent cavities, thereby producing a transitory channel spanning the entire transporter. A fully open channel exists in one inward-facing apo-conformer, (PDB 4ja4c) as demonstrated by several different tunnel-finding algorithms. The conformer interchanges produce a gated network within a branched central channel that permits staged ligand diffusion across the transporter during the open gate periods. Simulation of this model demonstrates that small-scale conformational changes required for sequentially opening gate with frequencies in the ns-μs time domain accommodate diffusive ligand flow between adjacent sites with association–dissociation rates in the μs-ms domain without imposing delays. This current model helps to unify the apparently opposing concepts of alternate access and multisite models of ligand transport.
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Affiliation(s)
- Philip Cunningham
- Department of Bioinformatics, School of Medicine, King’s College London, Waterloo Campus, Franklin–Wilkins Building, London, SE1 9NH UK
| | - Richard J. Naftalin
- Department of Physiology, School of Medicine, King’s College London, Waterloo Campus, Franklin–Wilkins Building, London, SE1 9NH UK
- BHF Centre of Research Excellence, School of Medicine, King’s College London, Waterloo Campus, Franklin–Wilkins Building, London, SE1 9NH UK
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15
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Cunningham P, Naftalin RJ. Implications of aberrant temperature-sensitive glucose transport via the glucose transporter deficiency mutant (GLUT1DS) T295M for the alternate-access and fixed-site transport models. J Membr Biol 2013; 246:495-511. [PMID: 23740044 DOI: 10.1007/s00232-013-9564-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 05/15/2013] [Indexed: 12/27/2022]
Abstract
In silico glucose docking to the transporter GLUT1 templated to the crystal structure of Escherichia coli XylE, a bacterial homolog of GLUT1-4 (4GBZ.pdb), reveals multiple docking sites. One site in the external vestibule in the exofacial linker between TM7 and -8 is adjacent to a missense T295M and a 4-mer insertion mutation. Glucose docking to the adjacent site is occluded in these mutants. These mutants cause an atypical form of glucose transport deficiency syndrome (GLUT1DS), where transport into the brain is deficient, although unusually transport into erythrocytes at 4 °C appears normal. A model in which glucose traverses the transporter via a network of saturable fixed sites simulates the temperature sensitivity of normal and mutant glucose influx and the mutation-dependent alterations of influx and efflux asymmetry when expressed in Xenopus oocytes at 37 °C. The explanation for the temperature sensitivity is that at 4 °C glucose influx between the external and internal vestibules is slow and causes glucose to accumulate in the external vestibule. This retards net glucose uptake from the external solution via two parallel sites into the external vestibule, consequently masking any transport defect at either one of these sites. At 37 °C glucose transit between the external and internal vestibules is rapid, with no significant glucose buildup in the external vestibule, and thereby unmasks any transport defect at one of the parallel input sites. Monitoring glucose transport in patients' erythrocytes at higher temperatures may improve the diagnostic accuracy of the functional test of GLUT1DS.
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Affiliation(s)
- Philip Cunningham
- Bioinformatics Division, School of Medicine, King's College London, Franklin-Wilkins Building, Waterloo Campus, London SE1 9HN, UK
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16
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Arsov T, Mullen SA, Rogers S, Phillips AM, Lawrence KM, Damiano JA, Goldberg-Stern H, Afawi Z, Kivity S, Trager C, Petrou S, Berkovic SF, Scheffer IE. Glucose transporter 1 deficiency in the idiopathic generalized epilepsies. Ann Neurol 2013; 72:807-15. [PMID: 23280796 DOI: 10.1002/ana.23702] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 05/07/2012] [Accepted: 05/25/2012] [Indexed: 01/14/2023]
Abstract
OBJECTIVE We examined whether glucose transporter 1 (GLUT1) deficiency causes common idiopathic generalized epilepsies (IGEs). METHODS The IGEs are common, heritable epilepsies that usually follow complex inheritance; currently little is known about their genetic architecture. Previously considered rare, GLUT1 deficiency, due to mutations in SLC2A1, leads to failure of glucose transport across the blood-brain barrier and inadequate glucose for brain metabolism. GLUT1 deficiency was first associated with an encephalopathy and more recently found in rare dominant families with epilepsy and paroxysmal exertional dyskinesia (PED). Five hundred four probands with IGEs and 470 controls underwent SLC2A1 sequencing. Glucose transport was assayed following expression of SLC2A1 variants in Xenopus oocytes. All available relatives were phenotyped, and SLC2A1 was sequenced. RESULTS Functionally validated mutations in SLC2A1 were present in 7 of 504 (1.4%) probands and 0 of 470 controls. PED, undiagnosed prior to study, occurred in 1 proband and 3 of 13 relatives with mutations. The IGEs in probands and relatives were indistinguishable from typical IGE. Three cases (0.6%) had mutations of large functional effect and showed autosomal dominant inheritance or were de novo. Four (0.8%) cases had a subtle functional effect; 2 showed possible dominant inheritance, and 2 did not. These alleles leading to subtle functional impairment may contribute to complex, polygenic inheritance of IGE. INTERPRETATION SLC2A1 mutations contribute to approximately 1% of IGE both as a dominant gene and as a susceptibility allele in complex inheritance. Diagnosis of GLUT1 deficiency has important treatment (ketogenic diet) and genetic counseling implications. The mechanism of restricted glucose delivery differs from the current focus on IGEs as ion channel disorders.
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Affiliation(s)
- Todor Arsov
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Melbourne, Australia
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17
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Yang H, Wang D, Engelstad K, Bagay L, Wei Y, Rotstein M, Aggarwal V, Levy B, Ma L, Chung WK, De Vivo DC. Glut1 deficiency syndrome and erythrocyte glucose uptake assay. Ann Neurol 2012; 70:996-1005. [PMID: 22190371 DOI: 10.1002/ana.22640] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE The Glut1 deficiency syndrome (Glut1 DS) phenotype has expanded dramatically since first described in 1991. Hypoglycorrhachia and decreased erythrocyte 3-OMG uptake are confirmatory laboratory biomarkers. The objective is to expand previous observations regarding the diagnostic value of the uptake assay. METHODS One hundred and nine suspected cases of Glut-1 DS were studied. All cases had a consistent clinical picture and hypoglycorrhachia. The uptake assay was decreased in 74 cases (group 1) and normal in 35 cases (group 2). We identified disease-causing mutations in 70 group 1 patients (95%) and one group 2 patient (3%). RESULTS The cut-off for an abnormally low uptake value was increased from 60% to 74% with a corresponding sensitivity of 99% and specificity of 100%. The correlation between the uptake values for the time-curve and the kinetic concentration curve were strongly positive (R(2) = 0.85). Significant group differences were found in CSF glucose and lactate values, tone abnormalities, and degree of microcephaly. Group 2 patients were less affected in all domains. We also noted a significant correlation between the mean erythrocyte 3-OMG uptake and clinical severity (R(2) = 0.94). INTERPRETATION These findings validate the erythrocyte glucose uptake assay as a confirmatory functional test for Glut1 DS and as a surrogate marker for GLUT1 haploinsufficiency.
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Affiliation(s)
- Hong Yang
- Colleen Giblin Laboratories for Pediatric Neurology Research, Department of Neurology, Columbia University, New York, NY 10032, USA
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18
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SLC2A1 gene analysis of Japanese patients with glucose transporter 1 deficiency syndrome. J Hum Genet 2011; 56:846-51. [PMID: 22011817 DOI: 10.1038/jhg.2011.115] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Glucose transporter 1 deficiency syndrome (Glut1-DS) is a congenital metabolic disorder characterized by refractory seizures with early infantile onset, developmental delay, movement disorders and acquired microcephaly. Glut1-DS is caused by heterozygous abnormalities of the SLC2A1 (Glut1) gene, whose product acts to transport glucose into the brain across the blood-brain barrier. We analyzed the SLC2A1 gene in 12 Japanese Glut1-DS patients who were diagnosed by characteristic clinical symptoms and hypoglycorrhachia as follows: all patients had infantile-onset seizures and mild to severe developmental delay, and ataxia was detected in 11 patients. For the 12 patients, we identified seven different mutations (three missense, one nonsense, two frameshift and one splice-site) in exons and exon-intron boundaries of the SLC2A1 gene by direct sequencing, of which six were novel mutations. Of the remaining five patients who had no point mutations and underwent investigation by multiplex ligation-dependent probe amplification, a complex abnormality with deletion and duplication was identified in one patient: this is the first case of such recombination of the SLC2A1 gene. Changes in regulatory sequences in the promoter region or genes other than SLC2A1 might be responsible for onset of Glut1-DS in the other four patients (33%) without SLC2A1 mutation.
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Anand G, Padeniya A, Hanrahan D, Scheffer H, Zaiwalla Z, Cox D, Mann N, Hewertson J, Price S, Nemeth A, Arsov T, Scheffer I, Jayawant S, Pike M, McShane T. Milder phenotypes of glucose transporter type 1 deficiency syndrome. Dev Med Child Neurol 2011; 53:664-8. [PMID: 21649651 DOI: 10.1111/j.1469-8749.2011.03949.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Glucose transporter type 1 deficiency syndrome (GLUT1DS) is a treatable condition resulting from impaired glucose transport into the brain. The classical presentation is with infantile-onset epilepsy and severe developmental delay. Non-classical phenotypes with movement disorders and early-onset absence epilepsy are increasingly recognized and the clinical spectrum is expanding. The hallmark is hypoglycorrhachia (cerebrospinal fluid [CSF] glucose<2.2 mmol/l) in the presence of normoglycaemia with a CSF/blood glucose ratio of less than 0.4. GLUT1DS is due to a mutation in the solute carrier family 2, member 1 gene (SLC2A1). We present five individuals (four males, one female), all of whom had a mild phenotype, highlighting the importance of considering this diagnosis in unexplained neurological disorders associated with mild learning difficulties, subtle motor delay, early-onset absence epilepsy, fluctuating gait disorders, and/or dystonia. The mean age at diagnosis was 8 years 8 months. This paper also shows phenotypical parallels between GLUT1DS and paroxysmal exertion-induced dyskinesia.
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Affiliation(s)
- Geetha Anand
- Department of Paediatric Neurology, John Radcliffe Hospital, Oxford, UK.
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Fujii T, Morimoto M, Yoshioka H, Ho YY, Law PPY, Wang D, De Vivo DC. T295M-associated Glut1 deficiency syndrome with normal erythrocyte 3-OMG uptake. Brain Dev 2011; 33:316-20. [PMID: 20630673 DOI: 10.1016/j.braindev.2010.06.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Revised: 06/04/2010] [Accepted: 06/17/2010] [Indexed: 12/01/2022]
Abstract
PURPOSE Glucose transporter type 1 (Glut1) is expressed in vascular endothelial cells comprising blood-brain barrier. Glut1 deficiency syndrome is characterized by low cerebrospinal fluid (CSF) concentration of glucose with normoglycemia, infantile seizure, acquired microcephaly, developmental delay and ataxia. As Glut1 is also expressed in erythrocytes, the diagnosis is confirmed by a decreased uptake of 3-O-methylglucose (3-OMG) into erythrocytes. However, patients with T295M mutation in the Glut1 gene show normal 3-OMG uptake. An in vitro study has proved that the T295M affects efflux rather than influx of glucose, explaining the discrepancy. However, the normal 3-OMG uptake in erythrocytes still indicates a possibility that the phenotype associated with this particular mutation may be milder. We compared the phenotype of three T295M-associated patients with that of other Glut1-deficient patients. PATIENTS AND METHODS Two patients are from our clinic and one is a patient reported elsewhere. The phenotype and biochemical data of patients with mutations other than T295M were obtained from a review and our previous report. RESULTS Despite the normal 3-OMG uptake into erythrocytes, all patients with T295M showed decreased glucose levels in CSF (33, 31 and 38mg/dl, respectively). The levels were comparable to those in patients with mutations other than T295M (31±4.3mg/dl (n=45)). All patients had convulsion, ataxia, speech delay, microcephaly and spasticity. CONCLUSION Despite the normal 3-OMG uptake in erythrocytes, phenotype of T295M-associated Glut1 deficiency was not significantly different from that of patients with a deficient 3-OMG uptake, indicating that T295M affects the glucose transport at the blood-brain barrier as much as other mutations.
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Affiliation(s)
- Tatsuya Fujii
- Department of Pediatrics, Shiga Medical Center for Children, 5-7-30 Moriyama, Shiga, Japan.
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Excellent response to acetazolamide in a case of paroxysmal dyskinesias due to GLUT1-deficiency. J Neurol 2010; 258:316-7. [PMID: 20830593 DOI: 10.1007/s00415-010-5702-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Accepted: 08/09/2010] [Indexed: 01/05/2023]
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Akman CI, Engelstad K, Hinton VJ, Ullner P, Koenigsberger D, Leary L, Wang D, De Vivo DC. Acute hyperglycemia produces transient improvement in glucose transporter type 1 deficiency. Ann Neurol 2010; 67:31-40. [DOI: 10.1002/ana.21797] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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