1
|
Giugno A, Falcone E, Fortunato F, Sammarra I, Procopio R, Gagliardi M, Bauleo A, de Stefano L, Martino I, Gambardella A. Glucose transporter-1 deficiency syndrome with extreme phenotypic variability in a five-generation family carrying a novel SLC2A1 variant. Eur J Neurol 2024; 31:e16325. [PMID: 38803061 PMCID: PMC11235872 DOI: 10.1111/ene.16325] [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: 02/29/2024] [Revised: 04/10/2024] [Accepted: 04/16/2024] [Indexed: 05/29/2024]
Abstract
BACKGROUND AND PURPOSE Glucose transporter-1 (GLUT1) deficiency syndrome (GLUT1-DS) is a metabolic disorder due to reduced expression of GLUT1, a glucose transporter of the central nervous system. GLUT1-DS is caused by heterozygous SLC2A1 variants that mostly arise de novo. Here, we report a large family with heterogeneous phenotypes related to a novel SLC2A1 variant. METHODS We present clinical and genetic features of a five-generation family with GLUT1-DS. RESULTS The 14 (nine living) affected members had heterogeneous phenotypes, including seizures (11/14), behavioral disturbances (5/14), mild intellectual disability (3/14), and/or gait disabilities (2/14). Brain magnetic resonance imaging revealed hippocampal sclerosis in the 8-year-old proband, who also had drug-responsive absences associated with attention-deficit/hyperactivity disorder. His 52-year-old father, who had focal epilepsy since childhood, developed paraparesis related to a reversible myelitis associated with hypoglycorrhachia. Molecular study detected a novel heterozygous missense variant (c.446C>T) in exon 4 of SLC2A1 (NM: 006516.2) that cosegregated with the illness. This variant causes an amino acid replacement (p.Pro149Leu) at the fourth transmembrane segment of GLUT1, an important domain located at its catalytic core. CONCLUSIONS Our study illustrates the extremely heterogenous phenotypes in familial GLUT1-DS, ranging from milder classic phenotypes to more subtle neurological disorder including paraparesis. This novel SLC2A1 variant (c.446C>T) provides new insight into the pathophysiology of GLUT1-DS.
Collapse
Affiliation(s)
- Alessia Giugno
- Department of Medical and Surgical Sciences, Institute of NeurologyUniversity Magna GræciaCatanzaroItaly
| | - Elena Falcone
- BIOGENET–Medical and Forensic Genetics LaboratoryCosenzaItaly
| | - Francesco Fortunato
- Department of Medical and Surgical Sciences, Institute of NeurologyUniversity Magna GræciaCatanzaroItaly
| | - Ilaria Sammarra
- Department of Medical and Surgical Sciences, Institute of NeurologyUniversity Magna GræciaCatanzaroItaly
| | - Radha Procopio
- Department of Medical and Surgical Sciences, Neuroscience Research CenterMagna Graecia UniversityCatanzaroItaly
| | - Monica Gagliardi
- Department of Medical and Surgical Sciences, Neuroscience Research CenterMagna Graecia UniversityCatanzaroItaly
| | - Alessia Bauleo
- BIOGENET–Medical and Forensic Genetics LaboratoryCosenzaItaly
| | | | - Iolanda Martino
- Department of Medical and Surgical Sciences, Institute of NeurologyUniversity Magna GræciaCatanzaroItaly
| | - Antonio Gambardella
- Department of Medical and Surgical Sciences, Institute of NeurologyUniversity Magna GræciaCatanzaroItaly
- Department of Medical and Surgical Sciences, Neuroscience Research CenterMagna Graecia UniversityCatanzaroItaly
| |
Collapse
|
2
|
Kim JH, Mailloux L, Bloor D, Maddox B, Humble J. The role of salt bridge networks in the stability of the yeast hexose transporter 1. Biochim Biophys Acta Gen Subj 2023; 1867:130490. [PMID: 37844739 DOI: 10.1016/j.bbagen.2023.130490] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 10/06/2023] [Accepted: 10/12/2023] [Indexed: 10/18/2023]
Abstract
BACKGROUND The yeast S. cerevisiae preferably metabolizes glucose through aerobic glycolysis. Glucose transport is facilitated by multiple hexose transporters (Hxts), and their expression and activity are tightly regulated by multiple mechanisms. However, detailed structural and functional analyses of Hxts remain limited, largely due to the lack of crystal structure. METHODS Homology modeling was used to build a 3D structural model for the yeast glucose transporter Hxt1 and investigate the effects of site directed mutations on Hxt1 stability and glucose transport activity. RESULTS The conserved salt bridge-forming residues observed in the human Glut4 and the yeast glucose receptor Rgt2 were identified within and between the two 6-transmembrane spanning segments of Hxt1. Most of the RGT2 mutations that disrupt the salt bridge networks were known to cause constitutive signal generation, whereas the corresponding substitutions in HXT1 were shown to decrease Hxt1 stability. While substitutions of the two residues in the salt bridge 2 in Glut4-E329Q and E393D-were reported to abolish glucose transport, the equivalent substitutions in Hxt1 (D382Q and E454D) did not affect Hxt1 glucose transport activity. CONCLUSIONS Substitutions of equivalent salt bridge-forming residues in Hxt1, Rgt2, and Glut4 are predicted to lock them in an inward-facing conformation but lead to different functional consequences. GENERAL SIGNIFICANCE The salt bridge networks in yeast and human glucose transporters and yeast glucose receptors may play different roles in maintaining their structural and functional integrity.
Collapse
Affiliation(s)
- Jeong-Ho Kim
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA 24502, USA.
| | - Levi Mailloux
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA 24502, USA
| | - Daniel Bloor
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA 24502, USA
| | - Bradley Maddox
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA 24502, USA
| | - Julia Humble
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA 24502, USA
| |
Collapse
|
3
|
Pascual JM, Jakkamsetti V, Málaga I, Noble D. Impoverished Conceptions of Gene Causation and Therapy in Developmental Neurology. Pediatr Neurol 2023; 148:198-205. [PMID: 37652816 DOI: 10.1016/j.pediatrneurol.2023.07.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Revised: 06/09/2023] [Accepted: 07/23/2023] [Indexed: 09/02/2023]
Abstract
We offer a primer to the modifiability of genetic neurological disease, particularly during development. One goal is to harness several unexpected observations made in the course of experimental gene modification or therapy into an explanatory conceptual context based on biological first principles. To this end, we anchor growing, disparate reports of unusual or untoward effects to a plausible framework wherein genes exhibit different degrees of modifiability and may result, when mutated or therapeutically modified, in unsuspected consequences. We propose that genetic pathogenic variant effects and modifiability depend on the number and complexity of associated protein-protein or higher-order interactions. Thus, gene malleability may range from that characteristic of the favorably modifiable primarily structural genes that subserve relatively invariant or circumscribed phenomena such as cell shape to that typical of some transcription factors, which are less functionally predictable when altered. The latter may be expressed developmentally, in compartmentalized manner, or only intermittently and yet exert vastly ramified influences sometimes circumscribed only to select species. We also argue that genetic diseases may steer the organism toward often poorly understood biological end points and co-opt multiple processes into hardly modifiable biology. Addition or modification of genes to approximate a normal state not previously experienced by the organism may lead to further aberration due to extraneous interference with the native biology of the disease state. Therefore, an understanding as perspicuous as possible of gene function, regulation, modifiability, and biological directionality down to seemingly minute but disease-relevant consequences is a prerequisite to intervention. Although we provide some groundwork steps to such an understanding, this may occasionally prove unattainable.
Collapse
Affiliation(s)
- Juan M Pascual
- Rare Brain Disorders Program, Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, Texas; Department of Physiology, The University of Texas Southwestern Medical Center, Dallas, Texas; Department of Pediatrics, The University of Texas Southwestern Medical Center, Dallas, Texas; Eugene McDermott Center for Human Growth & Development/Center for Human Genetics, The University of Texas Southwestern Medical Center, Dallas, Texas.
| | - Vikram Jakkamsetti
- Rare Brain Disorders Program, Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Ignacio Málaga
- Rare Brain Disorders Program, Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Denis Noble
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| |
Collapse
|
4
|
Solis EM, Good LB, Vázquez RG, Patnaik S, Hernandez-Reynoso AG, Ma Q, Angulo G, Dobariya A, Cogan SF, Pancrazio JJ, Pascual JM, Jakkamsetti V. Isolation of the murine Glut1 deficient thalamocortical circuit: wavelet characterization and reverse glucose dependence of low and gamma frequency oscillations. Front Neurosci 2023; 17:1191492. [PMID: 37829723 PMCID: PMC10565352 DOI: 10.3389/fnins.2023.1191492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 08/25/2023] [Indexed: 10/14/2023] Open
Abstract
Glucose represents the principal brain energy source. Thus, not unexpectedly, genetic glucose transporter 1 (Glut1) deficiency (G1D) manifests with encephalopathy. G1D seizures, which constitute a prominent disease manifestation, often prove refractory to medications but may respond to therapeutic diets. These seizures are associated with aberrant thalamocortical oscillations as inferred from human electroencephalography and functional imaging. Mouse electrophysiological recordings indicate that inhibitory neuron failure in thalamus and cortex underlies these abnormalities. This provides the motivation to develop a neural circuit testbed to characterize the mechanisms of thalamocortical synchronization and the effects of known or novel interventions. To this end, we used mouse thalamocortical slices on multielectrode arrays and characterized spontaneous low frequency oscillations and less frequent 30-50 Hz or gamma oscillations under near-physiological bath glucose concentration. Using the cortical recordings from layer IV among other regions recorded, we quantified oscillation epochs via an automated wavelet-based algorithm. This method proved analytically superior to power spectral density, short-time Fourier transform or amplitude-threshold detection. As expected from human observations, increased bath glucose reduced the lower frequency oscillations while augmenting the gamma oscillations, likely reflecting strengthened inhibitory neuron activity, and thus decreasing the low:high frequency ratio (LHR). This approach provides an ex vivo method for the evaluation of mechanisms, fuels, and pharmacological agents in a crucial G1D epileptogenic circuit.
Collapse
Affiliation(s)
- Elysandra M. Solis
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Levi B. Good
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Rafael Granja Vázquez
- Department of Neuroscience and the Center for Advanced Pain Studies, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Sourav Patnaik
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | | | - Qian Ma
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Gustavo Angulo
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Aksharkumar Dobariya
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Stuart F. Cogan
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Joseph J. Pancrazio
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Juan M. Pascual
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Physiology, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Pediatrics, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Eugene McDermott Center for Human Growth & Development/Center for Human Genetics, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Vikram Jakkamsetti
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| |
Collapse
|
5
|
Solis EM, Good LB, Granja Vázquez R, Patnaik S, Hernandez-Reynoso AG, Ma Q, Angulo G, Dobariya A, Cogan SF, Pancrazio JJ, Pascual JM, Jakkamsetti V. Isolation of the murine Glut1 deficient thalamocortical circuit: wavelet characterization and reverse glucose dependence of low and gamma frequency oscillations. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.05.543611. [PMID: 37645928 PMCID: PMC10461930 DOI: 10.1101/2023.06.05.543611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Glucose represents the principal brain energy source. Thus, not unexpectedly, genetic glucose transporter 1 (Glut1) deficiency (G1D) manifests with encephalopathy. G1D seizures, which constitute a prominent disease manifestation, often prove refractory to medications but may respond to therapeutic diets. These seizures are associated with aberrant thalamocortical oscillations as inferred from human electroencephalography and functional imaging. Mouse electrophysiological recordings indicate that inhibitory neuron failure in thalamus and cortex underlies these abnormalities. This provides the motivation to develop a neural circuit testbed to characterize the mechanisms of thalamocortical synchronization and the effects of known or novel interventions. To this end, we used mouse thalamocortical slices on multielectrode arrays and characterized spontaneous low frequency oscillations and less frequent 30-50 Hz or gamma oscillations under near-physiological bath glucose concentration. Using the cortical recordings from layer IV, we quantified oscillation epochs via an automated wavelet-based algorithm. This method proved analytically superior to power spectral density, short-time Fourier transform or amplitude-threshold detection. As expected from human observations, increased bath glucose reduced the lower frequency oscillations while augmenting the gamma oscillations, likely reflecting strengthened inhibitory neuron activity. This approach provides an ex vivo method for the evaluation of mechanisms, fuels, and pharmacological agents in a crucial G1D epileptogenic circuit.
Collapse
Affiliation(s)
- Elysandra M. Solis
- Department of Bioengineering; The University of Texas at Dallas, Richardson, Texas, USA
| | - Levi B. Good
- Department of Bioengineering; The University of Texas at Dallas, Richardson, Texas, USA
- 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
| | - Rafael Granja Vázquez
- Department of Bioengineering; The University of Texas at Dallas, Richardson, Texas, USA
| | - Sourav Patnaik
- Department of Bioengineering; The University of Texas at Dallas, Richardson, Texas, USA
| | | | - Qian Ma
- 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
| | - Gustavo Angulo
- 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
| | - Aksharkumar Dobariya
- 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
| | - Stuart F. Cogan
- Department of Bioengineering; The University of Texas at Dallas, Richardson, Texas, USA
| | - Joseph J. Pancrazio
- Department of Bioengineering; The University of Texas at Dallas, Richardson, 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
| | - Vikram Jakkamsetti
- Department of Bioengineering; The University of Texas at Dallas, Richardson, Texas, USA
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| |
Collapse
|
6
|
Avila A, Málaga I, Sirsi D, Kayani S, Primeaux S, Kathote GA, Jakkamsetti V, Kallem RR, Putnam WC, Park JY, Shinnar S, Pascual JM. Combination of triheptanoin with the ketogenic diet in Glucose transporter type 1 deficiency (G1D). Sci Rep 2023; 13:8951. [PMID: 37268656 DOI: 10.1038/s41598-023-36001-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Accepted: 05/27/2023] [Indexed: 06/04/2023] Open
Abstract
Fuel influx and metabolism replenish carbon lost during normal neural activity. Ketogenic diets studied in epilepsy, dementia and other disorders do not sustain such replenishment because their ketone body derivatives contain four carbon atoms and are thus devoid of this anaplerotic or net carbon donor capacity. Yet, in these diseases carbon depletion is often inferred from cerebral fluorodeoxyglucose-positron emission tomography. Further, ketogenic diets may prove incompletely therapeutic. These deficiencies provide the motivation for complementation with anaplerotic fuel. However, there are few anaplerotic precursors consumable in clinically sufficient quantities besides those that supply glucose. Five-carbon ketones, stemming from metabolism of the food supplement triheptanoin, are anaplerotic. Triheptanoin can favorably affect Glucose transporter type 1 deficiency (G1D), a carbon-deficiency encephalopathy. However, the triheptanoin constituent heptanoate can compete with ketogenic diet-derived octanoate for metabolism in animals. It can also fuel neoglucogenesis, thus preempting ketosis. These uncertainties can be further accentuated by individual variability in ketogenesis. Therefore, human investigation is essential. Consequently, we examined the compatibility of triheptanoin at maximum tolerable dose with the ketogenic diet in 10 G1D individuals using clinical and electroencephalographic analyses, glycemia, and four- and five-carbon ketosis. 4 of 8 of subjects with pre-triheptanoin beta-hydroxybutyrate levels greater than 2 mM demonstrated a significant reduction in ketosis after triheptanoin. Changes in this and the other measures allowed us to deem the two treatments compatible in the same number of individuals, or 50% of persons in significant beta-hydroxybutyrate ketosis. These results inform the development of individualized anaplerotic modifications to the ketogenic diet.ClinicalTrials.gov registration NCT03301532, first registration: 04/10/2017.
Collapse
Affiliation(s)
- Adrian Avila
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Mail Code 8813, Dallas, TX, 75390, USA
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Ignacio Málaga
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Mail Code 8813, Dallas, TX, 75390, USA
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Deepa Sirsi
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
- Department of Pediatrics, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Saima Kayani
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
- Department of Pediatrics, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Sharon Primeaux
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Mail Code 8813, Dallas, TX, 75390, USA
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Gauri A Kathote
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Mail Code 8813, Dallas, TX, 75390, USA
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Vikram Jakkamsetti
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Mail Code 8813, Dallas, TX, 75390, USA
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Raja Reddy Kallem
- Department of Pharmacy Practice and Clinical Pharmacology, Experimental Therapeutics Center, Texas Tech University Health Sciences Center, Dallas, TX, 75235, USA
| | - William C Putnam
- Department of Pharmacy Practice and Clinical Pharmacology, Experimental Therapeutics Center, Texas Tech University Health Sciences Center, Dallas, TX, 75235, USA
- Department of Pharmaceutical Science, Texas Tech University Health Sciences Center, Dallas, TX, 75235, USA
| | - Jason Y Park
- Department of Pathology, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Shlomo Shinnar
- Departments of Neurology and Pediatrics, Albert Einstein College of Medicine, Bronx, NY, 10467, USA
| | - Juan M Pascual
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Mail Code 8813, Dallas, TX, 75390, USA.
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
- Department of Pediatrics, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
- Department of Physiology, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
- Eugene McDermott Center for Human Growth & Development/Center for Human Genetics, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
| |
Collapse
|
7
|
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.
Collapse
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
| | | |
Collapse
|
8
|
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.
Collapse
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
| |
Collapse
|
9
|
Kathote G, Ma Q, Angulo G, Chen H, Jakkamsetti V, Dobariya A, Good LB, Posner B, Park JY, Pascual JM. Identification of Glucose Transport Modulators In Vitro and Method for Their Deep Learning Neural Network Behavioral Evaluation in Glucose Transporter 1-Deficient Mice. J Pharmacol Exp Ther 2023; 384:393-405. [PMID: 36635085 DOI: 10.1124/jpet.122.001428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 12/07/2022] [Accepted: 12/27/2022] [Indexed: 01/14/2023] Open
Abstract
Metabolic flux augmentation via glucose transport activation may be desirable in glucose transporter 1 (Glut1) deficiency syndrome (G1D) and dementia, whereas suppression might prove useful in cancer. Using lung adenocarcinoma cells that predominantly express Glut1 relative to other glucose transporters, we screened 9,646 compounds for effects on the accumulation of an extracellularly applied fluorescent glucose analog. Five drugs currently prescribed for unrelated indications or preclinically characterized robustly enhanced intracellular fluorescence. Additionally identified were 37 novel activating and nine inhibitory compounds lacking previous biologic characterization. Because few glucose-related mechanistic or pharmacological studies were available for these compounds, we developed a method to quantify G1D mouse behavior to infer potential therapeutic value. To this end, we designed a five-track apparatus to record and evaluate spontaneous locomotion videos. We applied this to a G1D mouse model that replicates the ataxia and other manifestations cardinal to the human disorder. Because the first two drugs that we examined in this manner (baclofen and acetazolamide) exerted various impacts on several gait aspects, we used deep learning neural networks to more comprehensively assess drug effects. Using this method, 49 locomotor parameters differentiated G1D from control mice. Thus, we used parameter modifiability to quantify efficacy on gait. We tested this by measuring the effects of saline as control and glucose as G1D therapy. The results indicate that this in vivo approach can estimate preclinical suitability from the perspective of G1D locomotion. This justifies the use of this method to evaluate our drugs or other interventions and sort candidates for further investigation. SIGNIFICANCE STATEMENT: There are few or no activators and few clinical inhibitors of glucose transport. Using Glut1-rich cells exposed to a glucose analog, we identified, in highthroughput fashion, a series of novel modulators. Some were drugs used to modify unrelated processes and some represented large but little studied chemical compound families. To facilitate their preclinical efficacy characterization regardless of potential mechanism of action, we developed a gait testing platform for deep learning neural network analysis of drug impact on Glut1-deficient mouse locomotion.
Collapse
Affiliation(s)
- Gauri Kathote
- Rare Brain Disorders Program, Department of Neurology (G.K., Q.M., G.A., V.J., A.D., L.B.G., J.M.P.), Department of Biochemistry (H.C., B.P.), Department of Pathology (J.Y.P.), Department of Physiology (J.M.P.), Department of Pediatrics (J.M.P.), and Eugene McDermott Center for Human Growth & Development/Center for Human Genetics (J.Y.P., J.M.P.), University of Texas Southwestern Medical Center, Dallas, Texas
| | - Qian Ma
- Rare Brain Disorders Program, Department of Neurology (G.K., Q.M., G.A., V.J., A.D., L.B.G., J.M.P.), Department of Biochemistry (H.C., B.P.), Department of Pathology (J.Y.P.), Department of Physiology (J.M.P.), Department of Pediatrics (J.M.P.), and Eugene McDermott Center for Human Growth & Development/Center for Human Genetics (J.Y.P., J.M.P.), University of Texas Southwestern Medical Center, Dallas, Texas
| | - Gustavo Angulo
- Rare Brain Disorders Program, Department of Neurology (G.K., Q.M., G.A., V.J., A.D., L.B.G., J.M.P.), Department of Biochemistry (H.C., B.P.), Department of Pathology (J.Y.P.), Department of Physiology (J.M.P.), Department of Pediatrics (J.M.P.), and Eugene McDermott Center for Human Growth & Development/Center for Human Genetics (J.Y.P., J.M.P.), University of Texas Southwestern Medical Center, Dallas, Texas
| | - Hong Chen
- Rare Brain Disorders Program, Department of Neurology (G.K., Q.M., G.A., V.J., A.D., L.B.G., J.M.P.), Department of Biochemistry (H.C., B.P.), Department of Pathology (J.Y.P.), Department of Physiology (J.M.P.), Department of Pediatrics (J.M.P.), and Eugene McDermott Center for Human Growth & Development/Center for Human Genetics (J.Y.P., J.M.P.), University of Texas Southwestern Medical Center, Dallas, Texas
| | - Vikram Jakkamsetti
- Rare Brain Disorders Program, Department of Neurology (G.K., Q.M., G.A., V.J., A.D., L.B.G., J.M.P.), Department of Biochemistry (H.C., B.P.), Department of Pathology (J.Y.P.), Department of Physiology (J.M.P.), Department of Pediatrics (J.M.P.), and Eugene McDermott Center for Human Growth & Development/Center for Human Genetics (J.Y.P., J.M.P.), University of Texas Southwestern Medical Center, Dallas, Texas
| | - Aksharkumar Dobariya
- Rare Brain Disorders Program, Department of Neurology (G.K., Q.M., G.A., V.J., A.D., L.B.G., J.M.P.), Department of Biochemistry (H.C., B.P.), Department of Pathology (J.Y.P.), Department of Physiology (J.M.P.), Department of Pediatrics (J.M.P.), and Eugene McDermott Center for Human Growth & Development/Center for Human Genetics (J.Y.P., J.M.P.), University of Texas Southwestern Medical Center, Dallas, Texas
| | - Levi B Good
- Rare Brain Disorders Program, Department of Neurology (G.K., Q.M., G.A., V.J., A.D., L.B.G., J.M.P.), Department of Biochemistry (H.C., B.P.), Department of Pathology (J.Y.P.), Department of Physiology (J.M.P.), Department of Pediatrics (J.M.P.), and Eugene McDermott Center for Human Growth & Development/Center for Human Genetics (J.Y.P., J.M.P.), University of Texas Southwestern Medical Center, Dallas, Texas
| | - Bruce Posner
- Rare Brain Disorders Program, Department of Neurology (G.K., Q.M., G.A., V.J., A.D., L.B.G., J.M.P.), Department of Biochemistry (H.C., B.P.), Department of Pathology (J.Y.P.), Department of Physiology (J.M.P.), Department of Pediatrics (J.M.P.), and Eugene McDermott Center for Human Growth & Development/Center for Human Genetics (J.Y.P., J.M.P.), University of Texas Southwestern Medical Center, Dallas, Texas
| | - Jason Y Park
- Rare Brain Disorders Program, Department of Neurology (G.K., Q.M., G.A., V.J., A.D., L.B.G., J.M.P.), Department of Biochemistry (H.C., B.P.), Department of Pathology (J.Y.P.), Department of Physiology (J.M.P.), Department of Pediatrics (J.M.P.), and Eugene McDermott Center for Human Growth & Development/Center for Human Genetics (J.Y.P., J.M.P.), University of Texas Southwestern Medical Center, Dallas, Texas.
| | - Juan M Pascual
- Rare Brain Disorders Program, Department of Neurology (G.K., Q.M., G.A., V.J., A.D., L.B.G., J.M.P.), Department of Biochemistry (H.C., B.P.), Department of Pathology (J.Y.P.), Department of Physiology (J.M.P.), Department of Pediatrics (J.M.P.), and Eugene McDermott Center for Human Growth & Development/Center for Human Genetics (J.Y.P., J.M.P.), University of Texas Southwestern Medical Center, Dallas, Texas.
| |
Collapse
|
10
|
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.
Collapse
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:
| |
Collapse
|
11
|
Rajasekaran K, Ma Q, Good LB, Kathote G, Jakkamsetti V, Liu P, Avila A, Primeaux S, Enciso Alva J, Markussen KH, Marin-Valencia I, Sirsi D, Hacker PMS, Gentry MS, Su J, Lu H, Pascual JM. Metabolic modulation of synaptic failure and thalamocortical hypersynchronization with preserved consciousness in Glut1 deficiency. Sci Transl Med 2022; 14:eabn2956. [PMID: 36197967 DOI: 10.1126/scitranslmed.abn2956] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Individuals with glucose transporter type I deficiency (G1D) habitually experience nutrient-responsive epilepsy associated with decreased brain glucose. However, the mechanistic association between blood glucose concentration and brain excitability in the context of G1D remains to be elucidated. Electroencephalography (EEG) in G1D individuals revealed nutrition time-dependent seizure oscillations often associated with preserved volition despite electrographic generalization and uniform average oscillation duration and periodicity, suggesting increased facilitation of an underlying neural loop circuit. Nonlinear EEG ictal source localization analysis and simultaneous EEG/functional magnetic resonance imaging converged on the thalamus-sensorimotor cortex as one potential circuit, and 18F-deoxyglucose positron emission tomography (18F-DG-PET) illustrated decreased glucose accumulation in this circuit. This pattern, reflected in a decreased thalamic to striatal 18F signal ratio, can aid with the PET imaging diagnosis of the disorder, whereas the absence of noticeable ictal behavioral changes challenges the postulated requirement for normal thalamocortical activity during consciousness. In G1D mice, 18F-DG-PET and mass spectrometry also revealed decreased brain glucose and glycogen, but preserved tricarboxylic acid cycle intermediates, indicating no overall energy metabolism failure. In brain slices from these animals, synaptic inhibition of cortical pyramidal neurons and thalamic relay neurons was decreased, and neuronal disinhibition was mitigated by metabolic sources of carbon; tonic-clonic seizures were also suppressed by α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor inhibition. These results pose G1D as a thalamocortical synaptic disinhibition disease associated with increased glucose-dependent neuronal excitability, possibly in relation to reduced glycogen. Together with findings in other metabolic defects, inhibitory neuron dysfunction is emerging as a modulable mechanism of hyperexcitability.
Collapse
Affiliation(s)
- Karthik Rajasekaran
- Rare Brain Disorders Program, Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Qian Ma
- Rare Brain Disorders Program, Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Levi B Good
- Rare Brain Disorders Program, Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Gauri Kathote
- Rare Brain Disorders Program, Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Vikram Jakkamsetti
- Rare Brain Disorders Program, Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Peiying Liu
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Adrian Avila
- Rare Brain Disorders Program, Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Sharon Primeaux
- Rare Brain Disorders Program, Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Julio Enciso Alva
- Department of Mathematics, University of Texas at Arlington, Arlington, TX 76019, USA
| | - Kia H Markussen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY 40506, USA
| | - Isaac Marin-Valencia
- Rare Brain Disorders Program, Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Deepa Sirsi
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Peter M S Hacker
- St. John's College and Department of Philosophy, University of Oxford, Oxford OX1 3JP, UK.,University College London Queen's Square Institute of Neurology, London WC1N 3BG, UK
| | - Matthew S Gentry
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY 40506, USA
| | - Jianzhong Su
- Department of Mathematics, University of Texas at Arlington, Arlington, TX 76019, USA
| | - Hanzhang Lu
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Juan M Pascual
- Rare Brain Disorders Program, Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.,Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.,Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.,Eugene McDermott Center for Human Growth and Development/Center for Human Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| |
Collapse
|
12
|
Olivotto S, Duse A, Bova SM, Leonardi V, Biganzoli E, Milanese A, Cereda C, Bertoli S, Previtali R, Veggiotti P. Glut1 deficiency syndrome throughout life: clinical phenotypes, intelligence, life achievements and quality of life in familial cases. Orphanet J Rare Dis 2022; 17:365. [PMID: 36153584 PMCID: PMC9509642 DOI: 10.1186/s13023-022-02513-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2022] [Accepted: 09/04/2022] [Indexed: 11/28/2022] Open
Abstract
Background Glut1 deficiency syndrome (Glut1-DS) is a rare metabolic encephalopathy. Familial forms are poorly investigated, and no previous studies have explored aspects of Glut1-DS over the course of life: clinical pictures, intelligence, life achievements, and quality of life in adulthood. Clinical, biochemical and genetic data in a cohort of familial Glut1-DS cases were collected from medical records. Intelligence was assessed using Raven’s Standard Progressive Matrices and Raven’s Colored Progressive Matrices in adults and children, respectively. An ad hoc interview focusing on life achievements and the World Health Organization Quality of Life Questionnaire were administered to adult subjects. Results The clinical picture in adults was characterized by paroxysmal exercise-induced dyskinesia (PED) (80%), fatigue (60%), low intelligence (60%), epilepsy (50%), and migraine (50%). However, 20% of the adults had higher-than-average intelligence. Quality of Life (QoL) seemed unrelated to the presence of PED or fatigue in adulthood. An association of potential clinical relevance, albeit not statistically significant, was found between intelligence and QoL. The phenotype of familial Glut1-DS in children was characterized by epilepsy (83.3%), intellectual disability (50%), and PED (33%). Conclusion The phenotype of familial Glut1-DS shows age-related differences: epilepsy predominates in childhood; PED and fatigue, followed by epilepsy and migraine, characterize the condition in adulthood. Some adults with familial Glut1-DS may lead regular and fulfilling lives, enjoying the same QoL as unaffected individuals. The disorder tends to worsen from generation to generation, with new and more severe symptoms arising within the same family. Epigenetic studies might be useful to assess the phenotypic variability in Glut1-DS. Supplementary Information The online version contains supplementary material available at 10.1186/s13023-022-02513-4.
Collapse
|
13
|
Klepper J, Akman C, Armeno M, Auvin S, Cervenka M, Cross HJ, De Giorgis V, Della Marina A, Engelstad K, Heussinger N, Kossoff EH, Leen WG, Leiendecker B, Monani UR, Oguni H, Neal E, Pascual JM, Pearson TS, Pons R, Scheffer IE, Veggiotti P, Willemsen M, Zuberi SM, De Vivo DC. Glut1 Deficiency Syndrome (Glut1DS): State of the art in 2020 and recommendations of the international Glut1DS study group. Epilepsia Open 2020; 5:354-365. [PMID: 32913944 PMCID: PMC7469861 DOI: 10.1002/epi4.12414] [Citation(s) in RCA: 132] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Revised: 06/13/2020] [Accepted: 06/16/2020] [Indexed: 12/14/2022] Open
Abstract
Glut1 deficiency syndrome (Glut1DS) is a brain energy failure syndrome caused by impaired glucose transport across brain tissue barriers. Glucose diffusion across tissue barriers is facilitated by a family of proteins including glucose transporter type 1 (Glut1). Patients are treated effectively with ketogenic diet therapies (KDT) that provide a supplemental fuel, namely ketone bodies, for brain energy metabolism. The increasing complexity of Glut1DS, since its original description in 1991, now demands an international consensus statement regarding diagnosis and treatment. International experts (n = 23) developed a consensus statement utilizing their collective professional experience, responses to a standardized questionnaire, and serial discussions of wide-ranging issues related to Glut1DS. Key clinical features signaling the onset of Glut1DS are eye-head movement abnormalities, seizures, neurodevelopmental impairment, deceleration of head growth, and movement disorders. Diagnosis is confirmed by the presence of these clinical signs, hypoglycorrhachia documented by lumbar puncture, and genetic analysis showing pathogenic SLC2A1 variants. KDT represent standard choices with Glut1DS-specific recommendations regarding duration, composition, and management. Ongoing research has identified future interventions to restore Glut1 protein content and function. Clinical manifestations are influenced by patient age, genetic complexity, and novel therapeutic interventions. All clinical phenotypes will benefit from a better understanding of Glut1DS natural history throughout the life cycle and from improved guidelines facilitating early diagnosis and prompt treatment. Often, the presenting seizures are treated initially with antiseizure drugs before the cause of the epilepsy is ascertained and appropriate KDT are initiated. Initial drug treatment fails to treat the underlying metabolic disturbance during early brain development, contributing to the long-term disease burden. Impaired development of the brain microvasculature is one such complication of delayed Glut1DS treatment in the postnatal period. This international consensus statement should facilitate prompt diagnosis and guide best standard of care for Glut1DS throughout the life cycle.
Collapse
Affiliation(s)
- Joerg Klepper
- Children's Hospital Aschaffenburg‐AlzenauAschaffenburgGermany
| | - Cigdem Akman
- Department of Neurology and PediatricsVagelos College of Physicians and Surgeons at Columbia UniversityNew YorkNYUSA
| | - Marisa Armeno
- Department of NutritionHospital Pediatria JP GarrahanBuenos AiresArgentina
| | - Stéphane Auvin
- Department of Pediatric NeurologyCHU Hôpital Robert DebreAPHPParisFrance
| | - Mackenzie Cervenka
- Department of NeurologyComprehensive Epilepsy CenterJohns Hopkins University School of MedicineBaltimoreMDUSA
| | - Helen J. Cross
- UCL NIHR BRC Great Ormond Street Institute of Child HealthLondonUK
| | | | - Adela Della Marina
- Department of Neuropediatrics, Developmental Neurology and Social Pediatrics, Centre for Neuromuscular Disorders in Children, University Hospital EssenUniversity of Duisburg‐EssenEssenGermany
| | - Kristin Engelstad
- Department of Neurology and PediatricsVagelos College of Physicians and Surgeons at Columbia UniversityNew YorkNYUSA
| | - Nicole Heussinger
- Department of Pediatric NeurologyParacelsus Medical Private UniversityNurembergGermany
| | - Eric H. Kossoff
- Departments of Neurology and PediatricsJohns Hopkins UniversityBaltimoreMDUSA
| | - Wilhelmina G. Leen
- Department of NeurologyCanisius Wilhemina HospitalNijmegenThe Netherlands
| | - Baerbel Leiendecker
- Department of Neuropediatrics, Developmental Neurology and Social Pediatrics, Centre for Neuromuscular Disorders in Children, University Hospital EssenUniversity of Duisburg‐EssenEssenGermany
| | - Umrao R. Monani
- Center for Motor Neuron Biology & DiseaseDepartments of Neurology and Pathology & Cell BiologyColumbia University Irving Medical CenterNew YorkNYUSA
| | - Hirokazu Oguni
- Department of PediatricsTokyo Women's Medical UniversityTokyoJapan
| | | | - Juan M. Pascual
- Departments of Neurology and Neurotherapeutics, Physiology and PediatricsEugene McDermott Center for Human Growth and DevelopmentThe University of Texas Southwestern Medical CenterDallasTXUSA
| | - Toni S. Pearson
- Mount Sinai Center for Headache & Pain MedicineNew YorkNYUSA
| | - Roser Pons
- First Department of PediatricsAgia Sofia HospitalUniversity of AthensAthensGreece
| | - Ingrid E. Scheffer
- Florey and Murdoch InstitutesAustin Health and Royal Children's HospitalThe University of MelbourneMelbourneVictoriaAustralia
| | - Pierangelo Veggiotti
- Pediatric Neurology V. Buzzi HospitalChild Neuropsychiatry University of MilanMilanItaly
| | - Michél Willemsen
- Department of Pediatric NeurologyRadboud University Medical CentreAmalia Children's HospitalNijmegenNetherlands
| | - Sameer M. Zuberi
- Royal Hospital for Children & College of Medical Veterinary & Life SciencesUniversity of GlasgowGlasgowUK
| | - Darryl C. De Vivo
- Department of Neurology and PediatricsVagelos College of Physicians and Surgeons at Columbia UniversityNew YorkNYUSA
| |
Collapse
|
14
|
Raja M, Kinne RKH. Mechanistic Insights into Protein Stability and Self-aggregation in GLUT1 Genetic Variants Causing GLUT1-Deficiency Syndrome. J Membr Biol 2020; 253:87-99. [PMID: 32025761 PMCID: PMC7150661 DOI: 10.1007/s00232-020-00108-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Accepted: 01/14/2020] [Indexed: 12/23/2022]
Abstract
Human sodium-independent glucose cotransporter 1 (hGLUT1) has been studied for its tetramerization and multimerization at the cell surface. Homozygous or compound heterozygous mutations in hGLUT1 elicit GLUT1-deficiency syndrome (GLUT1-DS), a metabolic disorder, which results in impaired glucose transport into the brain. The reduced cell surface expression or loss of function have been shown for some GLUT1 mutants. However, the mechanism by which deleterious mutations affect protein structure, conformational stability and GLUT1 oligomerization is not known and require investigation. In this review, we combined previous knowledge of GLUT1 mutations with hGLUT1 crystal structure to analyze native interactions and several natural single-point mutations. The modeling of native hGLUT1 structure confirmed the roles of native residues in forming a range of side-chain interactions. Interestingly, the modeled mutants pointed to the formation of a variety of non-native novel interactions, altering interaction networks and potentially eliciting protein misfolding. Self-aggregation of the last part of hGLUT1 was predicted using protein aggregation prediction tool. Furthermore, an increase in aggregation potential in the aggregation-prone regions was estimated for several mutants suggesting increased aggregation of misfolded protein. Protein stability change analysis predicted that GLUT1 mutant proteins are unstable. Combining GLUT1 oligomerization behavior with our modeling, aggregation prediction, and protein stability analyses, this work provides state-of-the-art view of GLUT1 genetic mutations that could destabilize native interactions, generate novel interactions, trigger protein misfolding, and enhance protein aggregation in a disease state.
Collapse
Affiliation(s)
- Mobeen Raja
- Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
- Algonquin College, 1385 Woodroffe Avenue, Ottawa, ON K2G 1V8 Canada
| | - Rolf K. H. Kinne
- Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
| |
Collapse
|
15
|
Canalp MB, Binder WH. Hybrid polymers bearing oligo-l-lysine(carboxybenzyl)s: synthesis and investigations of secondary structure. RSC Adv 2020; 10:1287-1295. [PMID: 35494681 PMCID: PMC9047569 DOI: 10.1039/c9ra09189k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 12/21/2019] [Indexed: 01/13/2023] Open
Abstract
Hybrid polymers of peptides resembling (partially) folded protein structures are promising materials in biomedicine, especially in view of folding-interactions between different segments. In this study polymers bearing repetitive peptidic folding elements, composed of N-terminus functionalized bis-ω-ene-functional oligo-l-lysine(carboxybenzyl(Z))s (Lysn) with repeating units (n) of 3, 6, 12, 24 and 30 were successfully synthesized to study their secondary structure introduced by conformational interactions between their chains. The pre-polymers of ADMET, narrowly dispersed Lysns, were obtained by ring opening polymerization (ROP) of N-carboxyanhydride (NCA) initiated with 11-amino-undecene, following N-terminus functionalization with 10-undecenoyl chloride. The resulting Lysns were subsequently polymerized via ADMET polymerization by using Grubbs’ first generation (G1) catalyst in 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) generating the ADMET polymers (A-[Lysn]m) (m = 2–12) with molecular weights ranging from 3 to 28 kDa, displaying polydispersity (Đ) values in the range of 1.5–3.2. After chemical analyses of Lysns and A-[Lysn]ms by 1H-NMR, GPC and MALDI-ToF MS, secondary structural investigations were probed by CD spectroscopy and IR spectroscopy in 2,2,2-trifluoroethanol (TFE). In order to study A-[Lysn]ms with defined molecular weights and low polydispersity values (Đ = 1.03–1.48), the ADMET polymers A-[Lysn=3]m=3 and A-[Lysn=24]m=4 were fractionated by preparative GPC, and subsequently analysed by 1H-NMR, analytical GPC, MALDI-ToF MS and CD spectroscopy. We can demonstrate the influence of chain length of the generated polymers on the formation of secondary structures by comparing Lysns with varying n values to the ADMET-polymers with the help of spectroscopic techniques such as CD and FTIR-spectroscopy in a helicogenic solvent. We demonstrate the influence of chain length of segmented polymers bearing dynamic folding elements onto the formation of secondary structures with the help of spectroscopic techniques such as CD and FTIR-spectroscopy in a helicogenic solvent.![]()
Collapse
Affiliation(s)
- Merve Basak Canalp
- Faculty of Natural Science II (Chemistry, Physics and Mathematics), Martin Luther University Halle-Wittenberg von-Danckelmann-Platz 4 Halle (Saale) D-06120 Germany
| | - Wolfgang H Binder
- Faculty of Natural Science II (Chemistry, Physics and Mathematics), Martin Luther University Halle-Wittenberg von-Danckelmann-Platz 4 Halle (Saale) D-06120 Germany
| |
Collapse
|
16
|
Madaan P, Jauhari P, Chakrabarty B, Gulati S. Jeavons syndrome in a family with GLUT1-deficiency syndrome. Seizure 2019; 71:158-160. [PMID: 31352161 DOI: 10.1016/j.seizure.2019.07.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Revised: 06/12/2019] [Accepted: 07/11/2019] [Indexed: 10/26/2022] Open
Affiliation(s)
- Priyanka Madaan
- Child Neurology Division, Department of Pediatrics, All India Institute of Medical Sciences (AIIMS), New Delhi, 110029, India
| | - Prashant Jauhari
- Child Neurology Division, Department of Pediatrics, All India Institute of Medical Sciences (AIIMS), New Delhi, 110029, India.
| | - Biswaroop Chakrabarty
- Child Neurology Division, Department of Pediatrics, All India Institute of Medical Sciences (AIIMS), New Delhi, 110029, India
| | - Sheffali Gulati
- Child Neurology Division, Department of Pediatrics, All India Institute of Medical Sciences (AIIMS), New Delhi, 110029, India
| |
Collapse
|
17
|
Varela MF, Kumar S. Strategies for discovery of new molecular targets for anti-infective drugs. Curr Opin Pharmacol 2019; 48:57-68. [PMID: 31146204 DOI: 10.1016/j.coph.2019.04.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 04/18/2019] [Accepted: 04/20/2019] [Indexed: 12/29/2022]
Abstract
Multidrug resistant bacterial pathogens as causative agents of infectious disease are a primary public health concern. Clinical efficacy of antimicrobial chemotherapy toward bacterial infection has been compromised in cases where causative agents are resistant to multiple structurally distinct antimicrobial agents. Modification of extant antimicrobial agents that exploit conventional bacterial targets have been developed since the advent of the antimicrobial era. This approach, while successful in certain cases, nonetheless suffers overall from the costs of development and rapid emergence of bacterial variants with confounding resistances to modified agents. Thus, additional strategies toward discovery of new molecular targets have been developed based on bioinformatics analyses and comparative genomics. These and other strategies meant to identify new molecular targets represent promising avenues for reducing emergence of bacterial infections. This short review considers these strategies for discovery of new molecular targets within bacterial pathogens.
Collapse
Affiliation(s)
- Manuel F Varela
- Department of Biology, Eastern New Mexico University, Portales, NM 88130, USA.
| | - Sanath Kumar
- Post Harvest Technology, ICAR-Central Institute of Fisheries Education, Seven Bungalows, Andheri (W), Mumbai, 400016, India
| |
Collapse
|
18
|
Oyarzabal A, Marin-Valencia I. Synaptic energy metabolism and neuronal excitability, in sickness and health. J Inherit Metab Dis 2019; 42:220-236. [PMID: 30734319 DOI: 10.1002/jimd.12071] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2018] [Revised: 01/06/2019] [Accepted: 01/30/2019] [Indexed: 12/11/2022]
Abstract
Most of the energy produced in the brain is dedicated to supporting synaptic transmission. Glucose is the main fuel, providing energy and carbon skeletons to the cells that execute and support synaptic function: neurons and astrocytes, respectively. It is unclear, however, how glucose is provided to and used by these cells under different levels of synaptic activity. It is even more unclear how diseases that impair glucose uptake and oxidation in the brain alter metabolism in neurons and astrocytes, disrupt synaptic activity, and cause neurological dysfunction, of which seizures are one of the most common clinical manifestations. Poor mechanistic understanding of diseases involving synaptic energy metabolism has prevented the expansion of therapeutic options, which, in most cases, are limited to symptomatic treatments. To shed light on the intersections between metabolism, synaptic transmission, and neuronal excitability, we briefly review current knowledge of compartmentalized metabolism in neurons and astrocytes, the biochemical pathways that fuel synaptic transmission at resting and active states, and the mechanisms by which disorders of brain glucose metabolism disrupt neuronal excitability and synaptic function and cause neurological disease in the form of epilepsy.
Collapse
Affiliation(s)
- Alfonso Oyarzabal
- Synaptic Metabolism Laboratory, Department of Neurology, Hospital Sant Joan de Deu, Barcelona, Spain
| | - Isaac Marin-Valencia
- Laboratory of Developmental Neurobiology, The Rockefeller University, New York, New York
| |
Collapse
|
19
|
Meyer K, Kirchner M, Uyar B, Cheng JY, Russo G, Hernandez-Miranda LR, Szymborska A, Zauber H, Rudolph IM, Willnow TE, Akalin A, Haucke V, Gerhardt H, Birchmeier C, Kühn R, Krauss M, Diecke S, Pascual JM, Selbach M. Mutations in Disordered Regions Can Cause Disease by Creating Dileucine Motifs. Cell 2018; 175:239-253.e17. [PMID: 30197081 DOI: 10.1016/j.cell.2018.08.019] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 06/09/2018] [Accepted: 08/08/2018] [Indexed: 01/12/2023]
Abstract
Many disease-causing missense mutations affect intrinsically disordered regions (IDRs) of proteins, but the molecular mechanism of their pathogenicity is enigmatic. Here, we employ a peptide-based proteomic screen to investigate the impact of mutations in IDRs on protein-protein interactions. We find that mutations in disordered cytosolic regions of three transmembrane proteins (GLUT1, ITPR1, and CACNA1H) lead to an increased clathrin binding. All three mutations create dileucine motifs known to mediate clathrin-dependent trafficking. Follow-up experiments on GLUT1 (SLC2A1), the glucose transporter causative of GLUT1 deficiency syndrome, revealed that the mutated protein mislocalizes to intracellular compartments. Mutant GLUT1 interacts with adaptor proteins (APs) in vitro, and knocking down AP-2 reverts the cellular mislocalization and restores glucose transport. A systematic analysis of other known disease-causing variants revealed a significant and specific overrepresentation of gained dileucine motifs in structurally disordered cytosolic domains of transmembrane proteins. Thus, several mutations in disordered regions appear to cause "dileucineopathies."
Collapse
Affiliation(s)
- Katrina Meyer
- Proteome Dynamics, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Marieluise Kirchner
- Proteome Dynamics, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Bora Uyar
- Bioinformatics Platform, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Jing-Yuan Cheng
- Proteome Dynamics, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Giulia Russo
- Molecular Pharmacology and Cell Biology, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Luis R Hernandez-Miranda
- Developmental Biology/Signal Transduction, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Anna Szymborska
- Integrative Vascular Biology Laboratory, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Robert-Rössle-Str. 10, 13125 Berlin, Germany; DZHK (German Centre for Cardiovascular Research) partner site, 13347 Berlin, Germany
| | - Henrik Zauber
- Proteome Dynamics, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Ina-Maria Rudolph
- Molecular Cardiovascular Research, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Thomas E Willnow
- Molecular Cardiovascular Research, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Altuna Akalin
- Bioinformatics Platform, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Volker Haucke
- Molecular Pharmacology and Cell Biology, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Holger Gerhardt
- Integrative Vascular Biology Laboratory, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Robert-Rössle-Str. 10, 13125 Berlin, Germany; DZHK (German Centre for Cardiovascular Research) partner site, 13347 Berlin, Germany; Berlin Institute of Health (BIH), 10178 Berlin, Germany
| | - Carmen Birchmeier
- Developmental Biology/Signal Transduction, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Ralf Kühn
- Berlin Institute of Health (BIH), 10178 Berlin, Germany; Core Facility Transgenics, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Michael Krauss
- Molecular Pharmacology and Cell Biology, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Sebastian Diecke
- DZHK (German Centre for Cardiovascular Research) partner site, 13347 Berlin, Germany; Berlin Institute of Health (BIH), 10178 Berlin, Germany; Core Facility Pluripotent Stem Cells, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Juan M Pascual
- Department of Neurology and Neurotherapeutics, UT Southwestern Medical Center, 5323 Harry Hines Blvd. Dallas, TX 75390, USA
| | - Matthias Selbach
- Proteome Dynamics, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Robert-Rössle-Str. 10, 13125 Berlin, Germany; Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany.
| |
Collapse
|
20
|
Hao J, Kelly DI, Su J, Pascual JM. Clinical Aspects of Glucose Transporter Type 1 Deficiency: Information From a Global Registry. JAMA Neurol 2017; 74:727-732. [PMID: 28437535 DOI: 10.1001/jamaneurol.2017.0298] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Importance Case reports regularly document unique or unusual aspects of glucose transporter type 1 deficiency (G1D). In contrast, population studies from which to draw global inferences are lacking. Twenty-five years after the earliest case reports, this deficiency still particularly affects treatment and prognostic counseling. Objective To examine the most common features of G1D. Design, Setting, and Participants In this study, data were collected electronically from 181 patients with G1D through a web-based, worldwide patient registry from December 1, 2013, through December 1, 2016. The study used several statistical methods tailored to address the age at onset of various forms of G1D, associated manifestations, natural history, treatment efficacy, and diagnostic procedures. These factors were correlated in a predictive mathematical model designed to guide prognosis on the basis of clinical features present at diagnosis. Results A total of 181 patients with G1D were included in the study (92 [50.8%] male and 89 female [49.2%]; median age, 9 years; age range, 0-65 years). As previously known, a relatively large variety of common phenotypes are characteristic of the G1D syndrome, including movement disorders, absence epilepsy (typical and atypical), and myoclonic and generalized epilepsies. The 3 main novel results are (1) the feasibility of effective dietary therapies (such as the modified Atkins diet) other than the ketogenic diet, (2) the relatively frequent occurrence (one-fourth of cases) of white matter magnetic resonance imaging abnormalities, and (3) the favorable effect of early diagnosis and treatment regardless of treatment modality and mutation type. In fact, the most important factor that determines outcome is age at diagnosis, as reflected in a predictive mathematical model. Conclusions and Relevance The results reveal several changing notions in the approach to G1D syndrome diagnosis and treatment, such as the perceived absolute requirement for a ketogenic diet, the assumed lack of structural brain defects, and the potential existence of genotype-phenotype correlations, all of which are contested by the registry data.
Collapse
Affiliation(s)
- Jian Hao
- Department of Mathematics, University of Texas at Arlington, Arlington
| | - Dorothy I Kelly
- Rare Brain Disorders Program, Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas
| | - Jianzhong Su
- Department of Mathematics, University of Texas at Arlington, Arlington
| | - Juan M Pascual
- Rare Brain Disorders Program, Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas3Department of Physiology, University of Texas Southwestern Medical Center, Dallas4Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas5Eugene McDermott Center for Human Growth & Development/Center for Human Genetics, University of Texas Southwestern Medical Center, Dallas
| |
Collapse
|
21
|
Lee HH, Hur YJ. Glucose transport 1 deficiency presenting as infantile spasms with a mutation identified in exon 9 of SLC2A1. KOREAN JOURNAL OF PEDIATRICS 2016; 59:S29-S31. [PMID: 28018440 PMCID: PMC5177706 DOI: 10.3345/kjp.2016.59.11.s29] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Revised: 12/08/2015] [Accepted: 12/16/2015] [Indexed: 12/02/2022]
Abstract
Glucose transport 1 (GLUT-1) deficiency is a rare syndrome caused by mutations in the glucose transporter 1 gene (SLC2A1) and is characterized by early-onset intractable epilepsy, delayed development, and movement disorder. De novo mutations and several hot spots in N34, G91, R126, R153, and R333 of exons 2, 3, 4, and 8 of SLC2A1 are associated with this condition. Seizures, one of the main clinical features of GLUT-1 deficiency, usually develop during infancy. Most patients experience brief and subtle myoclonic jerk and focal seizures that evolve into a mixture of different types of seizures, such as generalized tonic-clonic, absence, myoclonic, and complex partial seizures. Here, we describe the case of a patient with GLUT-1 deficiency who developed infantile spasms and showed delayed development at 6 months of age. She had intractable epilepsy despite receiving aggressive antiepileptic drug therapy, and underwent a metabolic workup. Cerebrospinal fluid (CSF) examination showed CSF-glucose-to-blood-glucose ratio of 0.38, with a normal lactate level. Bidirectional sequencing of SLC2A1 identified a missense mutation (c.1198C>T) at codon 400 (p.Arg400Cys) of exon 9.
Collapse
Affiliation(s)
- Hyun Hee Lee
- Department of Pediatrics, Inje University Haeundae Paik Hospital, Inje University College of Medicine, Busan, Korea
| | - Yun Jung Hur
- Department of Pediatrics, Inje University Haeundae Paik Hospital, Inje University College of Medicine, Busan, Korea
| |
Collapse
|
22
|
Lee J, Sands ZA, Biggin PC. A Numbering System for MFS Transporter Proteins. Front Mol Biosci 2016; 3:21. [PMID: 27314000 PMCID: PMC4889909 DOI: 10.3389/fmolb.2016.00021] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 05/17/2016] [Indexed: 11/13/2022] Open
Abstract
The Major Facilitator Superfamily (MFS) is one of the largest classes of secondary active transporters and is widely expressed in many domains of life. It is characterized by a common 12-transmembrane helix motif that allows the selective transport of a vast range of diverse substrates across the membrane. MFS transporters play a central role in many physiological processes and are increasingly recognized as potential drug targets. Despite intensive efforts, there are still only a handful of crystal structures and therefore homology modeling is likely to be a necessary process for providing models to interpret experiments for many years to come. However, the diversity of sequences and the multiple conformational states these proteins can exist in makes the process significantly more complicated, especially for sequences for which there is very little sequence identity to known templates. Inspired by the approach adopted many years ago for GPCRs, we have analyzed the large number of MFS sequences now available alongside the current structural information to propose a series of conserved contact points that can provide additional guidance for the homology modeling process. To enable cross-comparison across MFS models we also present a numbering scheme that can be used to provide a point of reference within each of the 12 transmembrane regions.
Collapse
Affiliation(s)
- Joanna Lee
- Department of Biochemistry, University of Oxford Oxford, UK
| | | | | |
Collapse
|
23
|
Fu X, Zhang G, Liu R, Wei J, Zhang-Negrerie D, Jian X, Gao Q. Mechanistic Study of Human Glucose Transport Mediated by GLUT1. J Chem Inf Model 2016; 56:517-26. [PMID: 26821218 DOI: 10.1021/acs.jcim.5b00597] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The glucose transporter 1 (GLUT1) belongs to the major facilitator superfamily (MFS) and is responsible for the constant uptake of glucose. However, the molecular mechanism of sugar transport remains obscure. In this study, homology modeling and molecular dynamics (MD) simulations in lipid bilayers were performed to investigate the combination of the alternate and multisite transport mechanism of glucose with GLUT1 in atomic detail. To explore the substrate recognition mechanism, the outward-open state human GLUT1 homology model was generated based on the template of xylose transporter XylE (PDB ID: 4GBZ), which shares up to 29% sequence identity and 49% similarity with GLUT1. Through the MD simulation study of glucose across lipid bilayer with both the outward-open GLUT1 and the GLUT1 inward-open crystal structure, we investigated six different conformational states and identified four key binding sites in both exofacial and endofacial loops that are essential for glucose recognition and transport. The study further revealed that four flexible gates consisting of W65/Y292/Y293-M420/TM10b-W388 might play important roles in the transport cycle. The study showed that some side chains close to the central ligand binding site underwent larger position changes. These conformational interchanges formed gated networks within an S-shaped central channel that permitted staged ligand diffusion across the transporter. This study provides new inroads for the understanding of GLUT1 ligand recognition paradigm and configurational features which are important for molecular, structural, and physiological research of the MFS members, especially for GLUT1-targeted drug design and discovery.
Collapse
Affiliation(s)
- Xuegang Fu
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University , Tianjin, 300072, P. R. China
| | - Gang Zhang
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University , Tianjin, 300072, P. R. China
| | - Ran Liu
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University , Tianjin, 300072, P. R. China
| | - Jing Wei
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University , Tianjin, 300072, P. R. China
| | - Daisy Zhang-Negrerie
- Concordia International School , 999 Mingyue Road, Shanghai, 201206, P. R. China
| | - Xiaodong Jian
- National Supercomputing Center in Tianjin , TEDA Service Outsourcing Industrial Park, Binhai New Area, Tianjin, 300457, P. R. China
| | - Qingzhi Gao
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University , Tianjin, 300072, P. R. China.,Tianjin University Collaborative Innovation Center of Chemical Science and Engineering , Tianjin, 300072, P. R. China
| |
Collapse
|
24
|
Pascual JM, Ronen GM. Glucose Transporter Type I Deficiency (G1D) at 25 (1990-2015): Presumptions, Facts, and the Lives of Persons With This Rare Disease. Pediatr Neurol 2015; 53:379-93. [PMID: 26341673 PMCID: PMC4609610 DOI: 10.1016/j.pediatrneurol.2015.08.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 07/30/2015] [Accepted: 08/02/2015] [Indexed: 12/20/2022]
Abstract
BACKGROUND As is often the case for rare diseases, the number of published reviews and case reports of glucose transporter type I deficiency (G1D) approaches or exceeds that of original research. This can indicate medical interest, but also scientific stagnation. METHODS In assessing this state of affairs here, we focus not on what is peculiar or disparate about G1D, but on the assumptions that have reigned thus far undisputed, and critique them as a potential impediment to progress. To summarize the most common G1D phenotype, we trace the 25-year story of G1D in parallel with the natural history of one of two index patients, identified in 1990 by one of us (G.M.R.) and brought up to date by the other (J.M.P.) while later examining widely repeated but little-scrutinized statements. Among them are those that pertain to assumptions about brain fuels; energy failure; cerebrospinal glucose concentration; the purpose of ketogenic diet; the role of the defective blood-brain barrier; genotype-phenotype correlations; a bewildering array of phenotypes; ictogenesis, seizures, and the electroencephalograph; the use of mice to model the disorder; and what treatments may and may not be expected to accomplish. RESULTS We reach the forgone conclusion that the proper study of mankind-and of one of its ailments (G1D) -is man itself (rather than mice, isolated cells, or extrapolated inferences) and propose a framework for rigorous investigation that we hope will lead to a better understanding and to better treatments for this and for rare disorders in general. CONCLUSIONS These considerations, together with experience drawn from other disorders, lead, as a logical consequence, to the nullification of the view that therapeutic development (i.e., trials) for rare diseases could or should be accelerated without the most vigorous scientific scrutiny: trial and error constitute an inseparable couple, such that, at the present time, hastening the former is bound to precipitate the latter.
Collapse
Affiliation(s)
- Juan M. Pascual
- Rare Brain Disorders Program, Departments of Neurology and Neurotherapeutics, Physiology and Pediatrics, and Eugene McDermott Center for Human Growth and Development / Center for Human Genetics. The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Gabriel M. Ronen
- Department of Pediatrics, McMaster Child Health Research Institute, McMaster University, Hamilton, Ontario, Canada
| |
Collapse
|
25
|
Zhang XC, Zhao Y, Heng J, Jiang D. Energy coupling mechanisms of MFS transporters. Protein Sci 2015; 24:1560-79. [PMID: 26234418 DOI: 10.1002/pro.2759] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 07/27/2015] [Accepted: 07/28/2015] [Indexed: 01/01/2023]
Abstract
Major facilitator superfamily (MFS) is a large class of secondary active transporters widely expressed across all life kingdoms. Although a common 12-transmembrane helix-bundle architecture is found in most MFS crystal structures available, a common mechanism of energy coupling remains to be elucidated. Here, we discuss several models for energy-coupling in the transport process of the transporters, largely based on currently available structures and the results of their biochemical analyses. Special attention is paid to the interaction between protonation and the negative-inside membrane potential. Also, functional roles of the conserved sequence motifs are discussed in the context of the 3D structures. We anticipate that in the near future, a unified picture of the functions of MFS transporters will emerge from the insights gained from studies of the common architectures and conserved motifs.
Collapse
Affiliation(s)
- Xuejun C Zhang
- National Laboratory of Macromolecules, National Center of Protein Science-Beijing, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China, 100101
| | - Yan Zhao
- National Laboratory of Macromolecules, National Center of Protein Science-Beijing, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China, 100101
| | - Jie Heng
- National Laboratory of Macromolecules, National Center of Protein Science-Beijing, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China, 100101
| | - Daohua Jiang
- National Laboratory of Macromolecules, National Center of Protein Science-Beijing, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China, 100101
| |
Collapse
|
26
|
Raja M, Kinne RKH. Pathogenic mutations causing glucose transport defects in GLUT1 transporter: The role of intermolecular forces in protein structure-function. Biophys Chem 2015; 200-201:9-17. [PMID: 25863194 DOI: 10.1016/j.bpc.2015.03.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 03/12/2015] [Accepted: 03/17/2015] [Indexed: 12/14/2022]
Abstract
Two families of glucose transporter - the Na(+)-dependent glucose cotransporter-1 (SGLT family) and the facilitated diffusion glucose transporter family (GLUT family) - play a crucial role in the translocation of glucose across the epithelial cell membrane. How genetic mutations cause life-threatening diseases like GLUT1-deficiency syndrome (GLUT1-DS) is not well understood. In this review, we have combined previous functional data with our in silico analyses of the bacterial homologue of GLUT members, XylE (an outward-facing, partly occluded conformation) and previously proposed GLUT1 homology model (an inward-facing conformation). A variety of native and mutant side chain interactions were modeled to highlight the potential roles of mutations in destabilizing protein-protein interaction hence triggering structural and functional defects. This study sets the stage for future studies of the structural properties that mediate GLUT1 dysfunction and further suggests that both SGLT and GLUT families share conserved domains that stabilize the transporter structure/function via a similar mechanism.
Collapse
Affiliation(s)
- Mobeen Raja
- Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany; Molecular Structure and Function, The Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada.
| | - Rolf K H Kinne
- Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany.
| |
Collapse
|
27
|
Chiba T, Matsuo H, Nagamori S, Nakayama A, Kawamura Y, Shimizu S, Sakiyama M, Hosoyamada M, Kawai S, Okada R, Hamajima N, Kanai Y, Shinomiya N. Identification of a hypouricemia patient with SLC2A9 R380W, a pathogenic mutation for renal hypouricemia type 2. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2015; 33:261-5. [PMID: 24940677 DOI: 10.1080/15257770.2013.857781] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Hypouricemia is characterized by low serum uric acid (SUA) levels (≤3.0 mg/dL) with complications such as urolithiasis and exercise-induced acute renal failure. We have previously reported that urate transporter 1 (URAT1/SLC22A12) and glucose transporter 9 (GLUT9/SLC2A9) are causative genes for renal hypouricemia type 1 (RHUC1) and renal hypouricemia type 2 (RHUC2), respectively. In the series of experiments, two families have been revealed to have RHUC2 due to GLUT9 missense mutations R198C or R380W, respectively. Thus far, however, no studies have reported other RHUC2 families or patients with these pathogenic mutations. This study is aimed to find other cases of RHUC2. We performed mutational analyses of GLUT9 exon 6 (for R198C) and exon 10 (for R380W) in 50 Japanese hypouricemia patients. Patients were analyzed out of a collection of more than 2000 samples from the Japan Multi-Institutional Collaborative Cohort Study (J-MICC Study). We identified a novel male patient with heterogeneous RHUC2 mutation R380W. The SUA of this hypouricemia patient was 2.6 mg/dL, which is similar to that of our previous report (SUA: 2.7 mg/dL). This is the second report indicating RHUC2 patient due to GLUT9 mutation R380W. This mutation occurs in highly conserved amino acid motifs and is reported to be an important membrane topology determinant. R380W is a dysfunctional mutation which completely diminishes the urate transport activities of GLUT9. Our study revealed a second hypouricemia patient with GLUT9 R380W, a pathogenic mutation of RHUC2, which may help to expand our understanding of RHUC pathogenesis.
Collapse
Affiliation(s)
- Toshinori Chiba
- a Department of Integrative Physiology and Bio-Nano Medicine , National Defense Medical College , Tokorozawa , Saitama , Japan
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Pascual JM. Glut1 Deficiency (G1D). Mov Disord 2015. [DOI: 10.1016/b978-0-12-405195-9.00050-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
|
29
|
Wisedchaisri G, Park MS, Iadanza MG, Zheng H, Gonen T. Proton-coupled sugar transport in the prototypical major facilitator superfamily protein XylE. Nat Commun 2014; 5:4521. [PMID: 25088546 PMCID: PMC4137407 DOI: 10.1038/ncomms5521] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 06/25/2014] [Indexed: 01/19/2023] Open
Abstract
The major facilitator superfamily (MFS) is the largest collection of structurally related membrane proteins that transport a wide array of substrates. The proton-coupled sugar transporter XylE is the first member of the MFS that has been structurally characterized in multiple transporting conformations, including both the outward and inward-facing states. Here we report the crystal structure of XylE in a new inward-facing open conformation, allowing us to visualize the rocker-switch movement of the N-domain against the C-domain during the transport cycle. Using molecular dynamics simulation, and functional transport assays, we describe the movement of XylE that facilitates sugar translocation across a lipid membrane and identify the likely candidate proton-coupling residues as the conserved Asp27 and Arg133. This study addresses the structural basis for proton-coupled substrate transport and release mechanism for the sugar porter family of proteins. Glucose transporters are a medically important class of membrane proteins often deregulated in diseases such as Type 2 diabetes. Here, Wisedchaisri et al. report the crystal structure of XylE in an inward-facing open conformation to provide a general mechanism of substrate transport for the sugar porter family of proteins.
Collapse
Affiliation(s)
- Goragot Wisedchaisri
- 1] Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, Virginia 20147, USA [2]
| | - Min-Sun Park
- 1] Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, Virginia 20147, USA [2]
| | - Matthew G Iadanza
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, Virginia 20147, USA
| | - Hongjin Zheng
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, Virginia 20147, USA
| | - Tamir Gonen
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, Virginia 20147, USA
| |
Collapse
|
30
|
Suppression of conformation-compromised mutants of Salmonella enterica serovar Typhimurium MelB. J Bacteriol 2014; 196:3134-9. [PMID: 24957620 DOI: 10.1128/jb.01868-14] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The crystal structure of the Na(+)-coupled melibiose permease of Salmonella enterica serovar Typhimurium (MelBSt) demonstrates that MelB is a member of the major facilitator superfamily of transporters. Arg residues at positions 295, 141, and 363 are involved in interdomain interactions at the cytoplasmic side by governing three clusters of electrostatic/polar interactions. Insertion of (one at a time) Glu, Leu, Gln, or Cys at positions R295, R141, and R363, or Lys at position R295, inhibits active transport of melibiose to a level of 2 to 20% of the value for wild-type (WT) MelBSt, with little effect on binding affinities for both sugar and Na(+). Interestingly, a spontaneous suppressor, D35E (periplasmic end of helix I), was isolated from the R363Q MelBSt mutant. Introduction of the D35E mutation in each of the mutants at R295, R141 (except R141E), or R363 rescues melibiose transport to up to 91% of the WT value. Single-site mutations for the pair of D35 and R175 (periplasmic end of helix VI) were constructed by replacing Asp with Glu, Gln, or Cys and R175 with Gln, Asn, or Cys. All mutants with mutations at R175 are active, indicating that a positive charge at R175 is not necessary. Mutant D35E shows reduced transport; D35Q and D35C are nearly inactivated. Surprisingly, the D35Q mutation partially rescues both R141C and R295Q mutations. The data support the idea that Arg at position 295 and a positive charge at positions 141 and 363 are required for melibiose transport catalyzed by MelBSt, and their mutation inhibits conformational cycling, which is suppressed by a minor modification at the opposite side of the membrane.
Collapse
|
31
|
Structure of the YajR transporter suggests a transport mechanism based on the conserved motif A. Proc Natl Acad Sci U S A 2013; 110:14664-9. [PMID: 23950222 DOI: 10.1073/pnas.1308127110] [Citation(s) in RCA: 135] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The major facilitator superfamily (MFS) is the largest family of secondary active transporters and is present in all life kingdoms. Detailed structural basis of the substrate transport and energy-coupling mechanisms of these proteins remain to be elucidated. YajR is a putative proton-driven MFS transporter found in many Gram-negative bacteria. Here we report the crystal structure of Escherichia coli YajR at 3.15 Å resolution in an outward-facing conformation. In addition to having the 12 canonical transmembrane helices, the YajR structure includes a unique 65-residue C-terminal domain which is independently stable. The structure is unique in illustrating the functional role of "sequence motif A." This highly conserved element is seen to stabilize the outward conformation of YajR and suggests a general mechanism for the conformational change between the inward and outward states of the MFS transporters.
Collapse
|
32
|
Gao X, Bai Y, Hwang TC. Cysteine scanning of CFTR's first transmembrane segment reveals its plausible roles in gating and permeation. Biophys J 2013; 104:786-97. [PMID: 23442957 DOI: 10.1016/j.bpj.2012.12.048] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Revised: 12/27/2012] [Accepted: 12/31/2012] [Indexed: 02/06/2023] Open
Abstract
Previous cysteine scanning studies of the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel have identified several transmembrane segments (TMs), including TM1, 3, 6, 9, and 12, as structural components of the pore. Some of these TMs such as TM6 and 12 may also be involved in gating conformational changes. However, recent results on TM1 seem puzzling in that the observed reactive pattern was quite different from those seen with TM6 and 12. In addition, whether TM1 also plays a role in gating motions remains largely unknown. Here, we investigated CFTR's TM1 by applying methanethiosulfonate (MTS) reagents from both cytoplasmic and extracellular sides of the membrane. Our experiments identified four positive positions, E92, K95, Q98, and L102, when the negatively charged MTSES was applied from the cytoplasmic side. Intriguingly, these four residues reside in the extracellular half of TM1 in previously defined CFTR topology; we thus extended our scanning to residues located extracellularly to L102. We found that cysteines introduced into positions 106, 107, and 109 indeed react with extracellularly applied MTS probes, but not to intracellularly applied reagents. Interestingly, whole-cell A107C-CFTR currents were very sensitive to changes of bath pH as if the introduced cysteine assumes an altered pKa-like T338C in TM6. These findings lead us to propose a revised topology for CFTR's TM1 that spans at least from E92 to Y109. Additionally, side-dependent modifications of these positions indicate a narrow region (L102-I106) that prevents MTS reagents from penetrating the pore, a picture similar to what has been reported for TM6. Moreover, modifications of K95C, Q98C, and L102C exhibit strong state dependency with negligible modification when the channel is closed, suggesting a significant rearrangement of TM1 during CFTR's gating cycle. The structural implications of these findings are discussed in light of the crystal structures of ABC transporters and homology models of CFTR.
Collapse
Affiliation(s)
- Xiaolong Gao
- Dalton Cardiovascular Research Center, University of Missouri-Columbia, Columbia, MO, USA
| | | | | |
Collapse
|
33
|
Transporter Proteins. Mol Pharmacol 2012. [DOI: 10.1002/9781118451908.ch5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
34
|
Kawamura Y, Matsuo H, Chiba T, Nagamori S, Nakayama A, Inoue H, Utsumi Y, Oda T, Nishiyama J, Kanai Y, Shinomiya N. Pathogenic GLUT9 mutations causing renal hypouricemia type 2 (RHUC2). NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2012; 30:1105-11. [PMID: 22132964 DOI: 10.1080/15257770.2011.623685] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
Abstract
Renal hypouricemia (MIM 220150) is an inherited disorder characterized by low serum uric acid levels and has severe complications such as exercise-induced acute renal failure and urolithiasis. We have previously reported that URAT1/SLC22A12 encodes a renal urate-anion exchanger and that its mutations cause renal hypouricemia type 1 (RHUC1). With the large health-examination database of the Japan Maritime Self-Defense Force, we found two missense mutations (R198C and R380W) of GLUT9/SLC2A9 in hypouricemia patients. R198C and R380W occur in highly conserved amino acid motifs in the "sugar transport proteins signatures" that are observed in GLUT family transporters. The corresponding mutations in GLUT1 (R153C and R333W) are known to cause GLUT1 deficiency syndrome because arginine residues in this motif are reportedly important as the determinants of the membrane topology of human GLUT1. Therefore, on the basis of membrane topology, the same may be true of GLUT9. GLUT9 mutants showed markedly reduced urate transport in oocyte expression studies, which would be the result of the loss of positive charges in those conserved amino acid motifs. Together with previous reports on GLUT9 localization, our findings suggest that these GLUT9 mutations cause renal hypouricemia type 2 (RHUC2) by their decreased urate reabsorption on both sides of the renal proximal tubule cells. However, a previously reported GLUT9 mutation, P412R, was unlikely to be pathogenic. These findings also enable us to propose a physiological model of the renal urate reabsorption via GLUT9 and URAT1 and can lead to a promising therapeutic target for gout and related cardiovascular diseases.
Collapse
Affiliation(s)
- Y Kawamura
- Department of Integrative Physiology and Bio-Nano Medicine, National Defense Medical College, Tokorozawa, Saitama, Japan
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Leturque A, Brot-Laroche E, Le Gall M. Carbohydrate intake. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 108:113-27. [PMID: 22656375 DOI: 10.1016/b978-0-12-398397-8.00005-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Carbohydrates represent more than 50% of the energy sources present in most human diets. Sugar intake is regulated by metabolic, neuronal, and hedonic factors, and gene polymorphisms are involved in determining sugar preference. Nutrigenomic adaptations to carbohydrate availability have been evidenced in metabolic diseases, in the persistence of lactose digestion, and in amylase gene copy number. Furthermore, dietary oligosaccharides, fermentable by gut flora, can modulate the microbiotal diversity to the benefit of the host. Genetic diseases linked to mutations in the disaccharidase genes (sucrase-isomaltase, lactase) and in sugar transporter genes (sodium/glucose cotransporter 1, glucose transporters 1 and 2) severely impact carbohydrate intake. These diseases are revealed upon exposure to food containing the offending sugar, and withdrawal of this sugar from the diet prevents disease symptoms, failure to thrive, and premature death. Tailoring the sugar composition of diets to optimize wellness and to prevent the chronic occurrence of metabolic diseases is a future goal that may yet be realized through continued development of nutrigenetics and nutrigenomics approaches.
Collapse
Affiliation(s)
- Armelle Leturque
- Department of Physiology, Metabolism, Differentiation, Centre de Recherche des Cordeliers, Paris, France
| | | | | |
Collapse
|
36
|
Stomatin-deficient cryohydrocytosis results from mutations in SLC2A1: a novel form of GLUT1 deficiency syndrome. Blood 2011; 118:5267-77. [DOI: 10.1182/blood-2010-12-326645] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
The hereditary stomatocytoses are a series of dominantly inherited hemolytic anemias in which the permeability of the erythrocyte membrane to monovalent cations is pathologically increased. The causative mutations for some forms of hereditary stomatocytosis have been found in the transporter protein genes, RHAG and SLC4A1. Glucose transporter 1 (glut1) deficiency syndromes (glut1DSs) result from mutations in SLC2A1, encoding glut1. Glut1 is the main glucose transporter in the mammalian blood-brain barrier, and glut1DSs are manifested by an array of neurologic symptoms. We have previously reported 2 cases of stomatin-deficient cryohydrocytosis (sdCHC), a rare form of stomatocytosis associated with a cold-induced cation leak, hemolytic anemia, and hepatosplenomegaly but also with cataracts, seizures, mental retardation, and movement disorder. We now show that sdCHC is associated with mutations in SLC2A1 that cause both loss of glucose transport and a cation leak, as shown by expression studies in Xenopus oocytes. On the basis of a 3-dimensional model of glut1, we propose potential mechanisms underlying the phenotypes of the 2 mutations found. We investigated the loss of stomatin during erythropoiesis and find this occurs during reticulocyte maturation and involves endocytosis. The molecular basis of the glut1DS, paroxysmal exercise-induced dyskinesia, and sdCHC phenotypes are compared and discussed.
Collapse
|
37
|
Gökben S, Yılmaz S, Klepper J, Serdaroğlu G, Tekgül H. Video/EEG recording of myoclonic absences in GLUT1 deficiency syndrome with a hot-spot R126C mutation in the SLC2A1 gene. Epilepsy Behav 2011; 21:200-2. [PMID: 21546317 DOI: 10.1016/j.yebeh.2011.03.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Revised: 03/15/2011] [Accepted: 03/19/2011] [Indexed: 11/15/2022]
Abstract
Glucose transporter type 1 deficiency syndrome (GLUT1DS) is an inborn error of brain energy metabolism characterized by impaired glucose transport into the brain. A classic phenotype comprising epilepsy, mental retardation, an often paroxysmal disorder, and several subtypes has been described. Although typical absences are frequent in GLUT1DS, myoclonic absence seizures are rarely reported. Here we describe a novel Turkish patient with a hot-spot mutation (R126C) in the SLC2A1 gene who presented with unusual myoclonic absence epilepsy and paroxysmal shivering. The case is discussed in view of eight other cases carrying the R126C mutation.
Collapse
Affiliation(s)
- Sarenur Gökben
- Child Neurology Division, Pediatrics Department, Ege University Faculty of Medicine, Bornova, İzmir, Turkey.
| | | | | | | | | |
Collapse
|
38
|
Takanaga H, Frommer WB. Facilitative plasma membrane transporters function during ER transit. FASEB J 2010; 24:2849-58. [PMID: 20354141 PMCID: PMC3230527 DOI: 10.1096/fj.09-146472] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Accepted: 02/25/2010] [Indexed: 11/11/2022]
Abstract
Although biochemical studies suggested a high permeability of the endoplasmic reticulum (ER) membrane for small molecules, proteomics identified few specialized ER transporters. To test functionality of transporters during ER passage, we tested whether glucose transporters (GLUTs, SGLTs) destined for the plasma membrane are active during ER transit. HepG2 cells were characterized by low-affinity ER transport activity, suggesting that ER uptake is protein mediated. The much-reduced capacity of HEK293T cells to take up glucose across the plasma membrane correlated with low ER transport. Ectopic expression of GLUT1, -2, -4, or -9 induced GLUT isoform-specific ER transport activity in HEK293T cells. In contrast, the Na(+)-glucose cotransporter SGLT1 mediated efficient plasma membrane glucose transport but no detectable ER uptake, probably because of lack of a sufficient sodium gradient across the ER membrane. In conclusion, we demonstrate that GLUTs are sufficient for mediating ER glucose transport en route to the plasma membrane. Because of the low volume of the ER, trace amounts of these uniporters contribute to ER solute import during ER transit, while uniporters and cation-coupled transporters carry out export from the ER, together potentially explaining the low selectivity of ER transport. Expression levels and residence time of transporters in the ER, as well as their coupling mechanisms, could be key determinants of ER permeability.
Collapse
Affiliation(s)
- Hitomi Takanaga
- Carnegie Institution for Science, Department of Plant Biology, Stanford, California, USA
| | - Wolf B. Frommer
- Carnegie Institution for Science, Department of Plant Biology, Stanford, California, USA
| |
Collapse
|
39
|
Price DRG, Tibbles K, Shigenobu S, Smertenko A, Russell CW, Douglas AE, Fitches E, Gatehouse AMR, Gatehouse JA. Sugar transporters of the major facilitator superfamily in aphids; from gene prediction to functional characterization. INSECT MOLECULAR BIOLOGY 2010; 19 Suppl 2:97-112. [PMID: 20482643 DOI: 10.1111/j.1365-2583.2009.00918.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Analysis of the pea aphid (Acyrthosiphon pisum) genome using signatures specific to the Major Facilitator Superfamily (Pfam Clan CL0015) and the Sugar_tr family (Pfam Family PF00083) has identified 54 genes encoding potential sugar transporters, of which 38 have corresponding ESTs. Twenty-nine genes contain the InterPro IPR003663 hexose transporter signature. The protein encoded by Ap_ST3, the most abundantly expressed sugar transporter gene, was functionally characterized by expression as a recombinant protein. Ap_ST3 acts as a low-affinity uniporter for fructose and glucose that does not depend on Na(+) or H(+) for activity. Ap_ST3 was expressed at elevated levels in distal gut tissue, consistent with a role in gut sugar transport. The A. pisum genome shows evidence of duplications of sugar transporter genes.
Collapse
|
40
|
Jiang X, McDermott JR, Ajees AA, Rosen BP, Liu Z. Trivalent arsenicals and glucose use different translocation pathways in mammalian GLUT1. Metallomics 2009; 2:211-9. [PMID: 21069159 DOI: 10.1039/b920471g] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Rat glucose transporter isoform 1 or rGLUT1, which is expressed in neonatal heart and the epithelial cells that form the blood-brain barrier, facilitates uptake of the trivalent arsenicals arsenite as As(OH)₃ and methylarsenite as CH₃As(OH)₂. GLUT1 may be the major pathway for arsenic uptake into heart and brain, where the metalloid causes cardiotoxicity and neurotoxicity. In this paper, we compare the translocation properties of GLUT1 for trivalent methylarsenite and glucose. Substitution of Ser(66), Arg(126) and Thr(310), residues critical for glucose uptake, led to decreased uptake of glucose but increased uptake of CH₃As(OH)₂. The K(m) for uptake of CH₃As(OH)₂ of three identified mutants, S66F, R126K and T310I, were decreased 4-10 fold compared to native GLUT1. The osmotic water permeability coefficient (P(f)) of GLUT1 and the three clinical isolates increased in parallel with the rate of CH₃As(OH)₂ uptake. GLUT1 inhibitors Hg(II), cytochalasin B and forskolin reduced uptake of glucose but not CH₃As(OH)₂. These results indicate that CH₃As(OH)₂ and water use a common translocation pathway in GLUT1 that is different to that of glucose transport.
Collapse
Affiliation(s)
- Xuan Jiang
- Department of Biochemistry, Wayne State University, School of Medicine, Detroit, Michigan, USA.
| | | | | | | | | |
Collapse
|
41
|
Matsuo H, Chiba T, Nagamori S, Nakayama A, Domoto H, Phetdee K, Wiriyasermkul P, Kikuchi Y, Oda T, Nishiyama J, Nakamura T, Morimoto Y, Kamakura K, Sakurai Y, Nonoyama S, Kanai Y, Shinomiya N. Mutations in glucose transporter 9 gene SLC2A9 cause renal hypouricemia. Am J Hum Genet 2008; 83:744-51. [PMID: 19026395 DOI: 10.1016/j.ajhg.2008.11.001] [Citation(s) in RCA: 283] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2008] [Revised: 10/27/2008] [Accepted: 11/04/2008] [Indexed: 11/16/2022] Open
Abstract
Renal hypouricemia is an inherited disorder characterized by impaired renal urate (uric acid) reabsorption and subsequent low serum urate levels, with severe complications such as exercise-induced acute renal failure and nephrolithiasis. We previously identified SLC22A12, also known as URAT1, as a causative gene of renal hypouricemia. However, hypouricemic patients without URAT1 mutations, as well as genome-wide association studies between urate and SLC2A9 (also called GLUT9), imply that GLUT9 could be another causative gene of renal hypouricemia. With a large human database, we identified two loss-of-function heterozygous mutations in GLUT9, which occur in the highly conserved "sugar transport proteins signatures 1/2." Both mutations result in loss of positive charges, one of which is reported to be an important membrane topology determinant. The oocyte expression study revealed that both GLUT9 isoforms showed high urate transport activities, whereas the mutated GLUT9 isoforms markedly reduced them. Our findings, together with previous reports on GLUT9 localization, suggest that these GLUT9 mutations cause renal hypouricemia by their decreased urate reabsorption on both sides of the renal proximal tubules. These findings also enable us to propose a physiological model of the renal urate reabsorption in which GLUT9 regulates serum urate levels in humans and can be a promising therapeutic target for gout and related cardiovascular diseases.
Collapse
Affiliation(s)
- Hirotaka Matsuo
- Department of Integrative Physiology and Bio-Nano Medicine, National Defense Medical College, Tokorozawa, Saitama, Japan.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|