1
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Zhen X, Betti M, Kars ME, Patterson A, Medina-Torres EA, Scheffler Mendoza SC, Herrera Sánchez DA, Lopez-Herrera G, Svyryd Y, Mutchinick O, Gamazon E, Rathmell J, Itan Y, Markle J, O'Farrill Romanillos P, Lugo-Reyes SO, Martinez-Barricarte R. Molecular and clinical characterization of a founder mutation causing G6PC3 deficiency. RESEARCH SQUARE 2024:rs.3.rs-4595246. [PMID: 39041036 PMCID: PMC11261954 DOI: 10.21203/rs.3.rs-4595246/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/24/2024]
Abstract
G6PC3 deficiency is a monogenic immunometabolic disorder that causes syndromic congenital neutropenia. Patients display heterogeneous extra-hematological manifestations, contributing to delayed diagnosis. Here, we investigated the origin and functional consequence of the G6PC3 c.210delC variant found in patients of Mexican origin. Based on the shared haplotypes amongst carriers of the c.210delC mutation, we estimated that this variant originated from a founder effect in a common ancestor. Furthermore, by ancestry analysis, we concluded that it originated in the indigenous Mexican population. At the protein level, we showed that this frameshift mutation leads to an aberrant protein expression in overexpression and patient-derived cells. G6PC3 pathology is driven by the intracellular accumulation of the metabolite 1,5-anhydroglucitol-6-phosphate (1,5-AG6P) that inhibits glycolysis. We characterized how the variant c.210delC impacts glycolysis by performing extracellular flux assays on patient-derived cells. When treated with 1,5-anhydroglucitol (1,5-AG), the precursor to 1,5-AG6P, patient-derived cells exhibited markedly reduced engagement of glycolysis. Finally, we compared the clinical presentation of patients with the mutation c.210delC and all other G6PC3 deficient patients reported in the literature to date, and we found that c.210delC carriers display all prominent clinical features observed in prior G6PC3 deficient patients. In conclusion, G6PC3 c.210delC is a loss-of-function mutation that arose from a founder effect in the indigenous Mexican population. These findings may facilitate the diagnosis of additional patients in this geographical area. Moreover, the in vitro 1,5-AG-dependent functional assay used in our study could be employed to assess the pathogenicity of additional G6PC3 variants.
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Affiliation(s)
- Xin Zhen
- Division of Genetic Medicine, Department of Medicine, Vanderbilt University Medical Center
| | - Michael Betti
- Division of Genetic Medicine, Department of Medicine, Vanderbilt University Medical Center
| | - Meltem Ece Kars
- The Charles Bronfman Institute for Personalized Medicine, Icahn School of Medicine at Mount Sinai
| | - Andrew Patterson
- Division of Molecular Pathogenesis, Department of Medicine, Vanderbilt University Medical Center
| | | | | | | | | | - Yevgeniya Svyryd
- Department of Genetics, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán
| | - Osvaldo Mutchinick
- Department of Genetics, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán
| | - Eric Gamazon
- Division of Genetic Medicine, Department of Medicine, Vanderbilt University Medical Center
| | - Jeffrey Rathmell
- Division of Molecular Pathogenesis, Department of Medicine, Vanderbilt University Medical Center
| | - Yuval Itan
- The Charles Bronfman Institute for Personalized Medicine, Icahn School of Medicine at Mount Sinai
| | - Janet Markle
- Division of Genetic Medicine, Department of Medicine, Vanderbilt University Medical Center
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Hawes EM, Rahim M, Haratipour Z, Orun AR, O'Rourke ML, Oeser JK, Kim K, Claxton DP, Blind RD, Young JD, O'Brien RM. Biochemical and metabolic characterization of a G6PC2 inhibitor. Biochimie 2024; 222:109-122. [PMID: 38431189 DOI: 10.1016/j.biochi.2024.02.012] [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: 02/14/2024] [Revised: 02/28/2024] [Accepted: 02/29/2024] [Indexed: 03/05/2024]
Abstract
Three glucose-6-phosphatase catalytic subunits, that hydrolyze glucose-6-phosphate (G6P) to glucose and inorganic phosphate, have been identified, designated G6PC1-3, but only G6PC1 and G6PC2 have been implicated in the regulation of fasting blood glucose (FBG). Elevated FBG has been associated with multiple adverse clinical outcomes, including increased risk for type 2 diabetes and various cancers. Therefore, G6PC1 and G6PC2 inhibitors that lower FBG may be of prophylactic value for the prevention of multiple conditions. The studies described here characterize a G6PC2 inhibitor, designated VU0945627, previously identified as Compound 3. We show that VU0945627 preferentially inhibits human G6PC2 versus human G6PC1 but activates human G6PC3. VU0945627 is a mixed G6PC2 inhibitor, increasing the Km but reducing the Vmax for G6P hydrolysis. PyRx virtual docking to an AlphaFold2-derived G6PC2 structural model suggests VU0945627 binds two sites in human G6PC2. Mutation of residues in these sites reduces the inhibitory effect of VU0945627. VU0945627 does not inhibit mouse G6PC2 despite its 84% sequence identity with human G6PC2. Mutagenesis studies suggest this lack of inhibition of mouse G6PC2 is due, in part, to a change in residue 318 from histidine in human G6PC2 to proline in mouse G6PC2. Surprisingly, VU0945627 still inhibited glucose cycling in the mouse islet-derived βTC-3 cell line. Studies using intact mouse liver microsomes and PyRx docking suggest that this observation can be explained by an ability of VU0945627 to also inhibit the G6P transporter SLC37A4. These data will inform future computational modeling studies designed to identify G6PC isoform-specific inhibitors.
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Affiliation(s)
- Emily M Hawes
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Mohsin Rahim
- Department of Chemical and Biomolecular Engineering, Vanderbilt School of Engineering, Nashville, TN, 37232, USA
| | - Zeinab Haratipour
- Austin Peay State University, 601 College St, Clarksville, TN 37044, USA; Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Abigail R Orun
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Margaret L O'Rourke
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - James K Oeser
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Kwangho Kim
- Department of Chemistry, Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, 37232, USA
| | - Derek P Claxton
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Ray D Blind
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Jamey D Young
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA; Department of Chemical and Biomolecular Engineering, Vanderbilt School of Engineering, Nashville, TN, 37232, USA
| | - Richard M O'Brien
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA.
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Zhen X, Betti MJ, Kars ME, Patterson A, Medina-Torres EA, Scheffler Mendoza SC, Herrera Sánchez DA, Lopez-Herrera G, Svyryd Y, Mutchinick OM, Gamazon E, Rathmell JC, Itan Y, Markle J, O’Farrill Romanillos P, Lugo-Reyes SO, Martinez-Barricarte R. Molecular and clinical characterization of a founder mutation causing G6PC3 deficiency. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2024:2024.05.13.24307299. [PMID: 38798393 PMCID: PMC11118594 DOI: 10.1101/2024.05.13.24307299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Background G6PC3 deficiency is a rare genetic disorder that causes syndromic congenital neutropenia. It is driven by the intracellular accumulation of a metabolite named 1,5-anhydroglucitol-6-phosphate (1,5-AG6P) that inhibits glycolysis. Patients display heterogeneous extra-hematological manifestations, contributing to delayed diagnosis. Objective The G6PC3 c.210delC variant has been identified in patients of Mexican origin. We set out to study the origin and functional consequence of this mutation. Furthermore, we sought to characterize the clinical phenotypes caused by it. Methods Using whole-genome sequencing data, we conducted haplotype analysis to estimate the age of this allele and traced its ancestral origin. We examined how this mutation affected G6PC3 protein expression and performed extracellular flux assays on patient-derived cells to characterize how this mutation impacts glycolysis. Finally, we compared the clinical presentations of patients with the c.210delC mutation relative to other G6PC3 deficient patients published to date. Results Based on the length of haplotypes shared amongst ten carriers of the G6PC3 c.210delC mutation, we estimated that this variant originated in a common ancestor of indigenous American origin. The mutation causes a frameshift that introduces a premature stop codon, leading to a complete loss of G6PC3 protein expression. When treated with 1,5-anhydroglucitol (1,5-AG), the precursor to 1,5-AG6P, patient-derived cells exhibited markedly reduced engagement of glycolysis. Clinically, c.210delC carriers display all the clinical features of syndromic severe congenital neutropenia type 4 observed in prior reports of G6PC3 deficiency. Conclusion The G6PC3 c.210delC is a loss-of-function mutation that arose from a founder effect in the indigenous Mexican population. These findings may facilitate the diagnosis of additional patients in this geographical area. Moreover, the in vitro 1,5-AG-dependent functional assay used in our study could be employed to assess the pathogenicity of additional G6PC3 variants.
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Affiliation(s)
- Xin Zhen
- Division of Genetic Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Division of Molecular Pathogenesis, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Michael J Betti
- Division of Genetic Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Genetics Institute, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Meltem Ece Kars
- The Charles Bronfman Institute for Personalized Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Andrew Patterson
- Division of Molecular Pathogenesis, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Center for Immunobiology, Nashville, TN, USA
| | | | | | | | - Gabriela Lopez-Herrera
- Immune deficiencies laboratory, National Institute of Pediatrics, Health Secretariat, Mexico City, Mexico
| | - Yevgeniya Svyryd
- Department of Genetics, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Osvaldo M. Mutchinick
- Department of Genetics, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Eric Gamazon
- Division of Genetic Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Genetics Institute, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jeffrey C Rathmell
- Division of Molecular Pathogenesis, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Center for Immunobiology, Nashville, TN, USA
- Vanderbilt Institute for Infection, Immunology and Inflammation, Nashville, TN, USA
| | - Yuval Itan
- The Charles Bronfman Institute for Personalized Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Janet Markle
- Division of Genetic Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Division of Molecular Pathogenesis, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Genetics Institute, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Center for Immunobiology, Nashville, TN, USA
- Vanderbilt Institute for Infection, Immunology and Inflammation, Nashville, TN, USA
| | | | - Saul Oswaldo Lugo-Reyes
- Immune deficiencies laboratory, National Institute of Pediatrics, Health Secretariat, Mexico City, Mexico
| | - Ruben Martinez-Barricarte
- Division of Genetic Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Division of Molecular Pathogenesis, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Genetics Institute, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Center for Immunobiology, Nashville, TN, USA
- Vanderbilt Institute for Infection, Immunology and Inflammation, Nashville, TN, USA
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Gul B, Firasat S, Shan T, Tehreem R, Afshan K. Mutational analysis and clinical investigations of medically diagnosed GSD 1a patients from Pakistan. PLoS One 2023; 18:e0288965. [PMID: 38033126 PMCID: PMC10688888 DOI: 10.1371/journal.pone.0288965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 07/07/2023] [Indexed: 12/02/2023] Open
Abstract
Glycogen storage disease type I (GSD I) is a rare autosomal recessive inborn error of carbohydrate metabolism caused by the defects of glucose-6-phosphatase complex (G6PC). Disease causing variants in the G6PC gene, located on chromosome 17q21 result in glycogen storage disease type Ia (GSD Ia). Age of onset of GSD Ia ranges from 0.5 to 25 years with presenting features including hemorrhage, hepatic, physical and blood related abnormalities. The overall goal of proposed study was clinical and genetic characterization of GSD Ia cases from Pakistani population. This study included forty GSD Ia cases presenting with heterogeneous clinical profile including hypoglycemia, hepatomegaly, lactic acidosis i.e., pH less than 7.2, hyperuricemia, seizures, epistaxis, hypertriglyceridemia (more than180 mg/dl) and sometimes short stature. All coding exons and intron-exon boundaries of G6PC gene were screened to identify pathogenic variant in 20 patients based on availability of DNA samples and willingness to participate in molecular analysis. Pathogenic variant analysis was done using PCR-Sanger sequencing method and pathogenic effect predictions for identified variants were carried out using PROVEAN, MutationTaster, Polyphen 2, HOPE, Varsome, CADD, DANN, SIFT and HSF software. Overall, 21 variants were detected including 8 novel disease causing variants i.e., G6PC (NM_000151.4):c.71A>C (p.Gln24Pro), c.109G>C(p.Ala37Pro), c.133G>C(p.Val45Leu), c.49_50insT c.205G>A(p.Asp69Asn), c.244C>A(p.Gln82Lys) c.322A>C(p.Thr108Pro) and c.322A>C(p.Cys284Tyr) in the screened regions of G6PC gene. Out of 13 identified polymorphisms, 3 were identified in heterozygous condition while 10 were found in homozygous condition. This study revealed clinical presentation of GSD Ia cases from Pakistan and identification of novel disease-causing sequence variants in coding region and intron-exon boundaries of G6PC gene.
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Affiliation(s)
- Bushra Gul
- Department of Zoology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
- Department of Biosciences, University of Wah, Wah Cantt, Pakistan
| | - Sabika Firasat
- Department of Zoology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Tayyaba Shan
- Department of Zoology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Raeesa Tehreem
- Department of Zoology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Kiran Afshan
- Department of Zoology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
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Shah A, Wondisford FE. Gluconeogenesis Flux in Metabolic Disease. Annu Rev Nutr 2023; 43:153-177. [PMID: 37603427 DOI: 10.1146/annurev-nutr-061121-091507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/23/2023]
Abstract
Gluconeogenesis is a critical biosynthetic process that helps maintain whole-body glucose homeostasis and becomes altered in certain medical diseases. We review gluconeogenic flux in various medical diseases, including common metabolic disorders, hormonal imbalances, specific inborn genetic errors, and cancer. We discuss how the altered gluconeogenic activity contributes to disease pathogenesis using data from experiments using isotopic tracer and spectroscopy methodologies. These in vitro, animal, and human studies provide insights into the changes in circulating levels of available gluconeogenesis substrates and the efficiency of converting those substrates to glucose by gluconeogenic organs. We highlight ongoing knowledge gaps, discuss emerging research areas, and suggest future investigations. A better understanding of altered gluconeogenesis flux may ultimately identify novel and targeted treatment strategies for such diseases.
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Affiliation(s)
- Ankit Shah
- Department of Medicine, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, New Jersey, USA; ,
| | - Fredric E Wondisford
- Department of Medicine, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, New Jersey, USA; ,
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Veiga-da-Cunha M, Wortmann SB, Grünert SC, Van Schaftingen E. Treatment of the Neutropenia Associated with GSD1b and G6PC3 Deficiency with SGLT2 Inhibitors. Diagnostics (Basel) 2023; 13:1803. [PMID: 37238286 PMCID: PMC10217388 DOI: 10.3390/diagnostics13101803] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 05/12/2023] [Accepted: 05/17/2023] [Indexed: 05/28/2023] Open
Abstract
Glycogen storage disease type Ib (GSD1b) is due to a defect in the glucose-6-phosphate transporter (G6PT) of the endoplasmic reticulum, which is encoded by the SLC37A4 gene. This transporter allows the glucose-6-phosphate that is made in the cytosol to cross the endoplasmic reticulum (ER) membrane and be hydrolyzed by glucose-6-phosphatase (G6PC1), a membrane enzyme whose catalytic site faces the lumen of the ER. Logically, G6PT deficiency causes the same metabolic symptoms (hepatorenal glycogenosis, lactic acidosis, hypoglycemia) as deficiency in G6PC1 (GSD1a). Unlike GSD1a, GSD1b is accompanied by low neutrophil counts and impaired neutrophil function, which is also observed, independently of any metabolic problem, in G6PC3 deficiency. Neutrophil dysfunction is, in both diseases, due to the accumulation of 1,5-anhydroglucitol-6-phosphate (1,5-AG6P), a potent inhibitor of hexokinases, which is slowly formed in the cells from 1,5-anhydroglucitol (1,5-AG), a glucose analog that is normally present in blood. Healthy neutrophils prevent the accumulation of 1,5-AG6P due to its hydrolysis by G6PC3 following transport into the ER by G6PT. An understanding of this mechanism has led to a treatment aimed at lowering the concentration of 1,5-AG in blood by treating patients with inhibitors of SGLT2, which inhibits renal glucose reabsorption. The enhanced urinary excretion of glucose inhibits the 1,5-AG transporter, SGLT5, causing a substantial decrease in the concentration of this polyol in blood, an increase in neutrophil counts and function and a remarkable improvement in neutropenia-associated clinical signs and symptoms.
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Affiliation(s)
- Maria Veiga-da-Cunha
- Metabolic Research Group, de Duve Institute and UCLouvain, B-1200 Brussels, Belgium
| | - Saskia B. Wortmann
- University Children’s Hospital, Paracelsus Medical University, 5020 Salzburg, Austria;
- Amalia Children’s Hospital, Radboudumc, 6525 Nijmegen, The Netherlands
| | - Sarah C. Grünert
- Department of General Pediatrics, Adolescent Medicine and Neonatology, Medical Center, Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany;
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Chou JY, Mansfield BC. Gene therapy and genome editing for type I glycogen storage diseases. FRONTIERS IN MOLECULAR MEDICINE 2023; 3:1167091. [PMID: 39086673 PMCID: PMC11285695 DOI: 10.3389/fmmed.2023.1167091] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 03/20/2023] [Indexed: 08/02/2024]
Abstract
Type I glycogen storage diseases (GSD-I) consist of two major autosomal recessive disorders, GSD-Ia, caused by a reduction of glucose-6-phosphatase-α (G6Pase-α or G6PC) activity and GSD-Ib, caused by a reduction in the glucose-6-phosphate transporter (G6PT or SLC37A4) activity. The G6Pase-α and G6PT are functionally co-dependent. Together, the G6Pase-α/G6PT complex catalyzes the translocation of G6P from the cytoplasm into the endoplasmic reticulum lumen and its subsequent hydrolysis to glucose that is released into the blood to maintain euglycemia. Consequently, all GSD-I patients share a metabolic phenotype that includes a loss of glucose homeostasis and long-term risks of hepatocellular adenoma/carcinoma and renal disease. A rigorous dietary therapy has enabled GSD-I patients to maintain a normalized metabolic phenotype, but adherence is challenging. Moreover, dietary therapies do not address the underlying pathological processes, and long-term complications still occur in metabolically compensated patients. Animal models of GSD-Ia and GSD-Ib have delineated the disease biology and pathophysiology, and guided development of effective gene therapy strategies for both disorders. Preclinical studies of GSD-I have established that recombinant adeno-associated virus vector-mediated gene therapy for GSD-Ia and GSD-Ib are safe, and efficacious. A phase III clinical trial of rAAV-mediated gene augmentation therapy for GSD-Ia (NCT05139316) is in progress as of 2023. A phase I clinical trial of mRNA augmentation for GSD-Ia was initiated in 2022 (NCT05095727). Alternative genetic technologies for GSD-I therapies, such as gene editing, are also being examined for their potential to improve further long-term outcomes.
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Affiliation(s)
- Janice Y. Chou
- Section on Cellular Differentiation, Division of Translational Medicine, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
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8
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Turki A, Stockler S, Sirrs S, Duddy K, Ho G, Elango R. Impact of hematopoietic stem cell transplantation in glycogen storage disease type Ib: A single-subject research design using 13C-glucose breath test. Mol Genet Metab Rep 2023; 34:100955. [PMID: 36632325 PMCID: PMC9826966 DOI: 10.1016/j.ymgmr.2023.100955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Accepted: 01/01/2023] [Indexed: 01/04/2023] Open
Abstract
Background Glycogen storage disease type Ib (GSD Ib) is an autosomal recessively inherited deficiency of the glucose-6-phosphate translocase (G6PT). Clinical features include a combination of a metabolic phenotype (fasting hypoglycemia, lactic acidosis, hepatomegaly) and a hematologic phenotype with neutropenia and neutrophil dysfunction. Dietary treatment involves provision of starches such as uncooked cornstarch (UCCS) and Glycosade® to provide prolonged enteral supply of glucose. Granulocyte colony-stimulating factor (G-CSF) is the treatment of choice for neutropenia. Because long-term stimulation of hematopoiesis with G-CSF causes serious complications such as splenomegaly, hypersplenism, and osteopenia; hematopoietic stem cell transplantation (HSCT) has been considered in some patients with GSD Ib to correct neutropenia and avoid G-CSF related adverse effects. Whether HSCT also has an effect on the metabolic phenotype and utilization of carbohydrate sources has not been determined. Objective Our objective was to measure the utilization of starch in a patient with GSD Ib before and after HSCT using the minimally invasive 13C-glucose breath test (13C-GBT). Design A case of GSD Ib (18y; female) underwent 13C-GBT four times: UCCS (pre-HSCT), UCCS (3, 5 months post-HSCT) and Glycosade® (6 months post-HSCT) with a dose of 80 g administered via nasogastric tube after a 4 h fast according to our patient's fasting tolerance. Breath samples were collected at baseline and every 30 min for 240 min. Rate of CO2 production was measured at 120 min using indirect calorimetry. Finger-prick blood glucose was measured using a glucometer hourly to test hypoglycemia (glucose <4 mmol/L). Biochemical and clinical data were obtained from the medical records as a post-hoc chart review. Results UCCS utilization was significantly higher in GSD Ib pre-HSCT, which reduced and stabilized 5 months post-HSCT. UCCS and Glycosade® utilizations were low and not different at 5 and 6 months post-HSCT. Blood glucose concentrations were not significantly different at any time point. Conclusions Findings show that HSCT stabilized UCCS utilization, as reflected by lower and stable glucose oxidation. The results also illustrate the application of 13C-GBT to examine glucose metabolism in response to various carbohydrate sources after other treatment modalities like HSCT in GSD Ib.
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Key Words
- 13C-GBT, 13C-glucose breath test
- 13C-glucose
- ALT, alanine aminotransferase
- AML, acute myeloid leukemia
- ANOVA, analysis of variance
- AST, aspartate aminotransferase
- AUC, area under the curve
- BIA, bioelectrical impedance analysis
- BMI, body mass index
- Breath test
- CF-IRMS, continuous flow isotope ratio mass spectrometer
- CGM, continuous glucose monitor
- CRP, C-reactive protein
- Cmax, maximum peak enrichment in 13CO2 oxidation
- ER, endoplasmic reticulum
- FFM, fat free mass
- FM, fat mass
- G-CSF, granulocyte colony-stimulating factor
- G6P, glucose-6-phosphate
- G6PT, glucose-6-phosphate translocase
- G6Pase-ß, glucose-6-phosphatase-β
- G6Pase-α, glucose-6-phosphatase-α
- GGT, gamma glutamyltransferase
- GSD I, glycogen storage disease type I
- GSD III, glycogen storage disease type III
- GSD Ia, glycogen storage disease type Ia
- GSD Ib, glycogen storage disease type Ib
- Glycogen storage disease type Ib
- Glycosade®
- HSCT/BMT, hematopoietic stem cell transplantation / bone marrow transplantation
- Hematopoietic stem cell transplantation
- IBD, inflammatory bowel disease
- IM, intramuscular
- NG, nasogastric
- TBW, total body water
- UCCS, uncooked cornstarch
- Uncooked cornstarch
- VCO2, rate of carbon dioxide production.
- tmax, time to reach maximum 13CO2 oxidation
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Affiliation(s)
- Abrar Turki
- BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada
- Department of Pediatrics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Sylvia Stockler
- BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada
- Department of Pediatrics, University of British Columbia, Vancouver, British Columbia, Canada
- Division of Biochemical Genetics, BC Children's Hospital, Vancouver, British Columbia, Canada
- Correspondence author to: Sylvia Stockler, Division of Biochemical Genetics, 4500 Oak St, BC Children's Hospital, Vancouver, BC V6H 3N1, Canada.
| | - Sandra Sirrs
- Department of Medicine, Division of Endocrinology, University of British Columbia, Vancouver, British Columbia, Canada
- Vancouver Costal Health, Adult Metabolic Diseases Clinic, Vancouver, British Columbia, Canada
| | - Kathleen Duddy
- Division of Biochemical Genetics, BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Gloria Ho
- Division of Biochemical Genetics, BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Rajavel Elango
- BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada
- Department of Pediatrics, University of British Columbia, Vancouver, British Columbia, Canada
- School of Population and Public Health, University of British Columbia, Vancouver, British Columbia, Canada
- Correspondence author to: Rajavel Elango, Rm170A, 950 West 28th Avenue, BC Children's Hospital Research Institute, Vancouver BC V5Z 4H4, Canada.
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Abdul Wahab SA, Yakob Y, Mohd Khalid MKN, Ali N, Leong HY, Ngu LH. Molecular, Biochemical, and Clinical Characterization of Thirteen Patients with Glycogen Storage Disease 1a in Malaysia. Genet Res (Camb) 2022; 2022:5870092. [PMID: 36160031 PMCID: PMC9489408 DOI: 10.1155/2022/5870092] [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: 03/17/2022] [Revised: 08/11/2022] [Accepted: 08/13/2022] [Indexed: 02/06/2023] Open
Abstract
Background Glycogen storage disease type 1a (GSD1a) is a rare autosomal recessive metabolic disorder characterized by hypoglycaemia, growth retardation, lactic acidosis, hepatomegaly, hyperlipidemia, and nephromegaly. GSD1a is caused by a mutation in the G6PC gene encoding glucose-6-phosphatase (G6Pase); an enzyme that catalyses the hydrolysis of glucose-6-phosphate (G6P) to phosphate and glucose. Objective To elaborate on the clinical findings, biochemical data, molecular genetic analysis, and short-term prognosis of 13 GSD1a patients in Malaysia. Methods The information about 13 clinically classified GSD1a patients was retrospectively studied. The G6PC mutation analysis was performed by PCR-DNA sequencing. Results Patients were presented with hepatomegaly (92%), hypoglycaemia (38%), poor weight gain (23%), and short stature (15%). Mutation analysis revealed nine heterozygous mutations; eight previously reported mutations (c.155 A > T, c.209 G > A, c.226 A > T, c.248 G > A, c.648 G > T, c.706 T > A, c.1022 T > A, c.262delG) and a novel mutation (c.325 T > C). The most common mutation found in Malaysian patients was c.648 G > T in ten patients (77%) of mostly Malay ethnicity, followed by c.248 G > A in 4 patients of Chinese ethnicity (30%). A novel missense mutation (c.325 T > C) was predicted to be disease-causing by various in silico software. Conclusions The establishment of G6PC molecular genetic testing will enable the detection of presymptomatic patients, assisting in genetic counselling while avoiding the invasive methods of liver biopsy.
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Affiliation(s)
- Siti Aishah Abdul Wahab
- Molecular Diagnostics Unit, Specialised Diagnostic Centre, Institute for Medical Research, National Institute of Health, Ministry of Health, Jalan Pahang 50586, Kuala Lumpur, Malaysia
| | - Yusnita Yakob
- Molecular Diagnostics Unit, Specialised Diagnostic Centre, Institute for Medical Research, National Institute of Health, Ministry of Health, Jalan Pahang 50586, Kuala Lumpur, Malaysia
| | - Mohd Khairul Nizam Mohd Khalid
- IEM & Genetic Unit, Nutrition Metabolic and Cardiovascular Research Centre, Institute for Medical Research, National Institute of Health, Ministry of Health, Kuala Lumpur, Malaysia
| | - Noraishah Ali
- Department of Genetics, Hospital Kuala Lumpur, Ministry of Health, Kuala Lumpur, Malaysia
| | - Huey Yin Leong
- Department of Genetics, Hospital Kuala Lumpur, Ministry of Health, Kuala Lumpur, Malaysia
| | - Lock Hock Ngu
- Department of Genetics, Hospital Kuala Lumpur, Ministry of Health, Kuala Lumpur, Malaysia
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10
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Rossi A, Rutten MGS, van Dijk TH, Bakker BM, Reijngoud DJ, Oosterveer MH, Derks TGJ. Dynamic Methods for Childhood Hypoglycemia Phenotyping: A Narrative Review. Front Endocrinol (Lausanne) 2022; 13:858832. [PMID: 35789807 PMCID: PMC9249565 DOI: 10.3389/fendo.2022.858832] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 04/27/2022] [Indexed: 11/25/2022] Open
Abstract
Hypoglycemia results from an imbalance between glucose entering the blood compartment and glucose demand, caused by a defect in the mechanisms regulating postprandial glucose homeostasis. Hypoglycemia represents one of the most common metabolic emergencies in childhood, potentially leading to serious neurologic sequelae, including death. Therefore, appropriate investigation of its specific etiology is paramount to provide adequate diagnosis, specific therapy and prevent its recurrence. In the absence of critical samples for biochemical studies, etiological assessment of children with hypoglycemia may include dynamic methods, such as in vivo functional tests, and continuous glucose monitoring. By providing detailed information on actual glucose fluxes in vivo, proof-of-concept studies have illustrated the potential (clinical) application of dynamic stable isotope techniques to define biochemical and clinical phenotypes of inherited metabolic diseases associated with hypoglycemia. According to the textbooks, individuals with glycogen storage disease type I (GSD I) display the most severe hypoglycemia/fasting intolerance. In this review, three dynamic methods are discussed which may be considered during both diagnostic work-up and monitoring of children with hypoglycemia: 1) functional in vivo tests; 2) in vivo metabolic profiling by continuous glucose monitoring (CGM); 3) stable isotope techniques. Future applications and benefits of dynamic methods in children with hypoglycemia are also discussed.
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Affiliation(s)
- Alessandro Rossi
- Section of Metabolic Diseases, Beatrix Children's Hospital, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
- Department of Translational Medicine, Section of Pediatrics, University of Naples "Federico II", Naples, Italy
| | - Martijn G S Rutten
- Laboratory of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Theo H van Dijk
- Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Barbara M Bakker
- Laboratory of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Dirk-Jan Reijngoud
- Laboratory of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Maaike H Oosterveer
- Laboratory of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Terry G J Derks
- Section of Metabolic Diseases, Beatrix Children's Hospital, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
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11
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Claxton DP, Overway EM, Oeser JK, O'Brien RM, Mchaourab HS. Biophysical and functional properties of purified glucose-6-phosphatase catalytic subunit 1. J Biol Chem 2021; 298:101520. [PMID: 34952005 PMCID: PMC8753184 DOI: 10.1016/j.jbc.2021.101520] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 12/10/2021] [Accepted: 12/17/2021] [Indexed: 11/18/2022] Open
Abstract
Glucose-6-phosphatase catalytic subunit 1 (G6PC1) plays a critical role in hepatic glucose production during fasting by mediating the terminal step of the gluconeogenesis and glycogenolysis pathways. In concert with accessory transport proteins, this membrane-integrated enzyme catalyzes glucose production from glucose-6-phosphate (G6P) to support blood glucose homeostasis. Consistent with its metabolic function, dysregulation of G6PC1 gene expression contributes to diabetes, and mutations that impair phosphohydrolase activity form the clinical basis of glycogen storage disease type 1a. Despite its relevance to health and disease, a comprehensive view of G6PC1 structure and mechanism has been limited by the absence of expression and purification strategies that isolate the enzyme in a functional form. In this report, we apply a suite of biophysical and biochemical tools to fingerprint the in vitro attributes of catalytically active G6PC1 solubilized in lauryl maltose neopentyl glycol (LMNG) detergent micelles. When purified from Sf9 insect cell membranes, the glycosylated mouse ortholog (mG6PC1) recapitulated functional properties observed previously in intact hepatic microsomes and displayed the highest specific activity reported to date. Additionally, our results establish a direct correlation between the catalytic and structural stability of mG6PC1, which is underscored by the enhanced thermostability conferred by phosphatidylcholine and the cholesterol analog cholesteryl hemisuccinate. In contrast, the N96A variant, which blocks N-linked glycosylation, reduced thermostability. The methodologies described here overcome long-standing obstacles in the field and lay the necessary groundwork for a detailed analysis of the mechanistic structural biology of G6PC1 and its role in complex metabolic disorders.
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Affiliation(s)
- Derek P Claxton
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA.
| | - Emily M Overway
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
| | - James K Oeser
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
| | - Richard M O'Brien
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
| | - Hassane S Mchaourab
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
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12
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Sambuceti G, Cossu V, Bauckneht M, Morbelli S, Orengo A, Carta S, Ravera S, Bruno S, Marini C. 18F-fluoro-2-deoxy-d-glucose (FDG) uptake. What are we looking at? Eur J Nucl Med Mol Imaging 2021; 48:1278-1286. [PMID: 33864142 DOI: 10.1007/s00259-021-05368-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Gianmario Sambuceti
- IRCCS Ospedale Policlinico San Martino, Nuclear Medicine, Largo Rosanna Benzi 10, 16132, Genoa, Italy. .,CNR Institute of Molecular Bioimaging and Physiology (IBFM), Milan, Italy.
| | - Vanessa Cossu
- Department of Health Sciences, University of Genoa, Genoa, Italy
| | - Matteo Bauckneht
- IRCCS Ospedale Policlinico San Martino, Nuclear Medicine, Largo Rosanna Benzi 10, 16132, Genoa, Italy
| | - Silvia Morbelli
- IRCCS Ospedale Policlinico San Martino, Nuclear Medicine, Largo Rosanna Benzi 10, 16132, Genoa, Italy.,Department of Health Sciences, University of Genoa, Genoa, Italy
| | - AnnaMaria Orengo
- IRCCS Ospedale Policlinico San Martino, Nuclear Medicine, Largo Rosanna Benzi 10, 16132, Genoa, Italy
| | - Sonia Carta
- IRCCS Ospedale Policlinico San Martino, Nuclear Medicine, Largo Rosanna Benzi 10, 16132, Genoa, Italy
| | - Silvia Ravera
- Department of Experimental Medicine, Human Anatomy, University of Genoa, Genoa, Italy
| | - Silvia Bruno
- Department of Experimental Medicine, Human Anatomy, University of Genoa, Genoa, Italy
| | - Cecilia Marini
- IRCCS Ospedale Policlinico San Martino, Nuclear Medicine, Largo Rosanna Benzi 10, 16132, Genoa, Italy.,CNR Institute of Molecular Bioimaging and Physiology (IBFM), Milan, Italy
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13
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Marcalo J, Oliveira A, Nunes PA, do Vale S. Type la glycogen storage disease complicated with diabetes mellitus: the role of flash continuous glucose monitoring. BMJ Case Rep 2021; 14:14/3/e240489. [PMID: 33766968 PMCID: PMC8006771 DOI: 10.1136/bcr-2020-240489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
A 22-year-old woman with type Ia glycogen storage disease was referred to the endocrinology department with new-onset diabetes mellitus-glycated haemoglobin (HbA1c) of 8.2%. She had suffered from repeated bouts of hypoglycaemia since the first days of her life. The diagnosis was made at 5 months old, after clinical investigations revealed mixed dyslipidaemia, lactic acidosis and hepatomegaly. Compound heterozygosity was documented at the age of 4. The basis of her initial treatment was starch and reinforced soy milk, ingested multiple times a day and night. The patient suffered from obesity since childhood. This case shows a rare association between glycogen storage disease type Ia and diabetes mellitus. A multidisciplinary approach was implemented. Through diet and use of flash continuous glucose monitoring, we were able to improve patient's adherence and metabolic profile. Hypoglycaemia and hyperglycaemia risk significantly decreased; 86% time in range (70-180 mg/dL), 6% hypoglycaemia and 6.3% HbA1c in recent evaluations.
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Affiliation(s)
- Jose Marcalo
- Serviço de Endocrinologia, Centro Hospitalar Universitário Lisboa Norte EPE, Lisboa, Portugal
| | - Anabela Oliveira
- Serviço de Medicina I, Centro Hospitalar Universitário Lisboa Norte EPE, Lisboa, Portugal
| | - Patrícia Almeida Nunes
- Serviço de Dietética e Nutrição, Centro Hospitalar Universitário Lisboa Norte EPE, Lisboa, Portugal
| | - Sónia do Vale
- Serviço de Endocrinologia, Centro Hospitalar Universitário Lisboa Norte EPE, Lisboa, Portugal
- Serviço de Endocrinologia, Universidade de Lisboa Faculdade de Medicina, Lisboa, Portugal
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14
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Katayama D, Baba H, Kuwabara T, Kido J, Mitsubuchi H, Matsumoto S, Nakamura K. SGLT2 inhibition alleviated hyperglycemia, glucose intolerance, and dumping syndrome-like symptoms in a patient with glycogen storage disease type Ia: a case report. J Med Case Rep 2021; 15:75. [PMID: 33588940 PMCID: PMC7885476 DOI: 10.1186/s13256-020-02658-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 12/28/2020] [Indexed: 11/18/2022] Open
Abstract
Background Glycogen storage disease (GSD) type Ia is a glycogenesis disorder with long-term complications such as hepatomegaly and renal dysfunction and is caused by congenital loss of glucose-6-phosphatase (G6Pase) expression. G6Pase is essential for the final step of gluconeogenesis and glycogenolysis, and its deficiency causes clinical hypoglycemia in the fasting state during infancy. Contrastingly, patients also show blood glucose trends and glucose intolerance similar to those in type II diabetes. Owing to the contrasting presentation of hypoglycemia with glucose intolerance, glucose control in patients remains a challenge, requiring management of both fasting hypoglycemia and post-prandial hyperglycemia. Case presentation The patient was a 45-year old Asian (Japanese) woman who showed disease onset at 3 years of age, when hypoglycemia and hepatomegaly were observed, and GDS type Ia was diagnosed by the lack of G6Pase activity. Over the past 45 years, she presented hyperglycemia and dumping syndrome like symptoms (a feeling of fullness, even after eating just a small amount, abdominal cramping, nausea, sweating, flushing, or light-headedness and rapid heartbeat) at 2 hours after food intake. Her liver and kidney dysfunction also worsened over time. Treatment with exercise combined with a sodium-glucose co-transporter 2 inhibitor and an alpha glucosidase inhibitor alleviated her glucose intolerance and dumping syndrome-like symptoms, without increasing hypoglycemic events. Conclusion This case suggests SGLT2 inhibitor as a promising candidate for treating glucose intolerance in GSD type Ia without worsening of hypoglycemia.
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Affiliation(s)
- Daisuke Katayama
- Department of Pediatrics, Kumamoto University Hospital, Honjo 1-1-1, Kumamoto City, Japan
| | - Hiroo Baba
- Department of Endocrinology, Beppu Hospital, Saifu 1-6-23, Dazaifu City, Japan
| | - Takashige Kuwabara
- Department of Nephrology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto City, Japan
| | - Jun Kido
- Department of Pediatrics, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto City, Kumamoto Prefecture, 860-8556, Japan
| | - Hiroshi Mitsubuchi
- Division of Neonatology, Kumamoto University Hospital, Honjo 1-1-1, Kumamoto City, Japan
| | - Shirou Matsumoto
- Department of Pediatrics, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto City, Kumamoto Prefecture, 860-8556, Japan.
| | - Kimitoshi Nakamura
- Department of Pediatrics, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto City, Kumamoto Prefecture, 860-8556, Japan
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15
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Yuan X, Ma W, Wu X, Xing X, Li Y, Wang O, Zhang H, Yang H. Successful treatment of diabetes associated with glycogen storage disease type Ia. Diabet Med 2021; 38:e14373. [PMID: 32740965 DOI: 10.1111/dme.14373] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Revised: 07/09/2020] [Accepted: 07/27/2020] [Indexed: 11/29/2022]
Affiliation(s)
- X Yuan
- Department of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - W Ma
- Department of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - X Wu
- Department of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - X Xing
- Department of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Y Li
- Department of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - O Wang
- Department of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - H Zhang
- Department of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - H Yang
- Department of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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16
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Xu Q, Tang H, Duan L, Zuo X, Shi X, Li Y, Zhao H, Zhang H. A novel SLC37A4 missense mutation in GSD-Ib without hepatomegaly causes enhanced leukocytes endoplasmic reticulum stress and apoptosis. Mol Genet Genomic Med 2020; 9:e1568. [PMID: 33280276 PMCID: PMC7963412 DOI: 10.1002/mgg3.1568] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 11/08/2020] [Accepted: 11/16/2020] [Indexed: 11/19/2022] Open
Abstract
Background Glycogen storage disease (GSD) type Ib is an autosomal recessive disease caused by defects of glucose‐6‐phosphate transporter (G6PT), encoded by the SLC37A4 gene. To date, over 100 mutations have been revealed in the SLC37A4 gene. GSD‐Ib patients manifest a metabolic phenotype of impaired blood glucose homeostasis and also carry the additional complications of neutropenia and myeloid dysfunction. Methods Here, we present two daughters with an initial diagnosis of gout in a Chinese consanguineous family. Whole‐exome sequencing was performed to identify the mutations. The mechanism of leukocytopenia was investigated. Results Whole‐exome sequencing analysis of the proband identified a novel homozygous p.P119L mutation in SLC37A4, leading to a diagnosis of GSD‐Ib. We found that the potential pathogenic p.P119L mutation leads to an unusual phenotype characterized by gout at onset, and GSD‐Ib arising from this variant also manifests multiple metabolic abnormalities, leukocytopenia, and anemia, but no hepatomegaly. The leukocytes from the proband showed increased mRNA levels of sXBP‐1, BIP, and CHOP genes in the unfolded protein response pathway, and enhanced Bax mRNA and caspase‐3 activity, which might contribute to leukocytopenia. Conclusion Our findings broaden the variation spectrum of SLC37A4 and suggest no strict genotype–phenotype correlations in GSD‐Ib patients.
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Affiliation(s)
- Qianyun Xu
- Department of Rheumatology, Xiangya Hospital, Central South University, Changsha, China
| | - Haiyan Tang
- Department of Medical Genetics, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Liping Duan
- Department of Rheumatology, Xiangya Hospital, Central South University, Changsha, China
| | - Xiaoxia Zuo
- Department of Rheumatology, Xiangya Hospital, Central South University, Changsha, China
| | - Xiaoliu Shi
- Department of Medical Genetics, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Yisha Li
- Department of Rheumatology, Xiangya Hospital, Central South University, Changsha, China.,Department of Pathophysiology, Xiangya School of Medicine, Central South University, Changsha, China
| | - Hongjun Zhao
- Department of Rheumatology, Xiangya Hospital, Central South University, Changsha, China
| | - Huali Zhang
- Department of Rheumatology, Xiangya Hospital, Central South University, Changsha, China.,Department of Pathophysiology, Xiangya School of Medicine, Central South University, Changsha, China.,Sepsis Translational Medicine Key Laboratory of Hunan, Central South University, Changsha, China
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17
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Dienel GA. Hypothesis: A Novel Neuroprotective Role for Glucose-6-phosphatase (G6PC3) in Brain-To Maintain Energy-Dependent Functions Including Cognitive Processes. Neurochem Res 2020; 45:2529-2552. [PMID: 32815045 DOI: 10.1007/s11064-020-03113-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/10/2020] [Accepted: 08/13/2020] [Indexed: 12/11/2022]
Abstract
The isoform of glucose-6-phosphatase in liver, G6PC1, has a major role in whole-body glucose homeostasis, whereas G6PC3 is widely distributed among organs but has poorly-understood functions. A recent, elegant analysis of neutrophil dysfunction in G6PC3-deficient patients revealed G6PC3 is a neutrophil metabolite repair enzyme that hydrolyzes 1,5-anhydroglucitol-6-phosphate, a toxic metabolite derived from a glucose analog present in food. These patients exhibit a spectrum of phenotypic characteristics and some have learning disabilities, revealing a potential linkage between cognitive processes and G6PC3 activity. Previously-debated and discounted functions for brain G6PC3 include causing an ATP-consuming futile cycle that interferes with metabolic brain imaging assays and a nutritional role involving astrocyte-neuron glucose-lactate trafficking. Detailed analysis of the anhydroglucitol literature reveals that it competes with glucose for transport into brain, is present in human cerebrospinal fluid, and is phosphorylated by hexokinase. Anhydroglucitol-6-phosphate is present in rodent brain and other organs where its accumulation can inhibit hexokinase by competition with ATP. Calculated hexokinase inhibition indicates that energetics of brain and erythrocytes would be more adversely affected by anhydroglucitol-6-phosphate accumulation than heart. These findings strongly support the paradigm-shifting hypothesis that brain G6PC3 removes a toxic metabolite, thereby maintaining brain glucose metabolism- and ATP-dependent functions, including cognitive processes.
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Affiliation(s)
- Gerald A Dienel
- Department of Neurology, University of Arkansas for Medical Sciences, 4301 W. Markham St., Mail Slot 500, Little Rock, AR, 72205, USA.
- Department of Cell Biology and Physiology, University of New Mexico School of Medicine, Albuquerque, NM, 87131, USA.
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18
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Bosma KJ, Rahim M, Singh K, Goleva SB, Wall ML, Xia J, Syring KE, Oeser JK, Poffenberger G, McGuinness OP, Means AL, Powers AC, Li WH, Davis LK, Young JD, O’Brien RM. Pancreatic islet beta cell-specific deletion of G6pc2 reduces fasting blood glucose. J Mol Endocrinol 2020; 64:235-248. [PMID: 32213654 PMCID: PMC7331801 DOI: 10.1530/jme-20-0031] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 03/13/2020] [Indexed: 12/25/2022]
Abstract
The G6PC1, G6PC2 and G6PC3 genes encode distinct glucose-6-phosphatase catalytic subunit (G6PC) isoforms. In mice, germline deletion of G6pc2 lowers fasting blood glucose (FBG) without affecting fasting plasma insulin (FPI) while, in isolated islets, glucose-6-phosphatase activity and glucose cycling are abolished and glucose-stimulated insulin secretion (GSIS) is enhanced at submaximal but not high glucose. These observations are all consistent with a model in which G6PC2 regulates the sensitivity of GSIS to glucose by opposing the action of glucokinase. G6PC2 is highly expressed in human and mouse islet beta cells however, various studies have shown trace G6PC2 expression in multiple tissues raising the possibility that G6PC2 also affects FBG through non-islet cell actions. Using real-time PCR we show here that expression of G6pc1 and/or G6pc3 are much greater than G6pc2 in peripheral tissues, whereas G6pc2 expression is much higher than G6pc3 in both pancreas and islets with G6pc1 expression not detected. In adult mice, beta cell-specific deletion of G6pc2 was sufficient to reduce FBG without changing FPI. In addition, electronic health record-derived phenotype analyses showed no association between G6PC2 expression and phenotypes clearly unrelated to islet function in humans. Finally, we show that germline G6pc2 deletion enhances glycolysis in mouse islets and that glucose cycling can also be detected in human islets. These observations are all consistent with a mechanism by which G6PC2 action in islets is sufficient to regulate the sensitivity of GSIS to glucose and hence influence FBG without affecting FPI.
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Affiliation(s)
- Karin J. Bosma
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Mohsin Rahim
- Department of Chemical and Biomolecular Engineering, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Kritika Singh
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Slavina B. Goleva
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Martha L. Wall
- Department of Chemical and Biomolecular Engineering, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Jing Xia
- Departments of Cell Biology and of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390-9039
| | - Kristen E. Syring
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - James K. Oeser
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Greg Poffenberger
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Owen P. McGuinness
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Anna L. Means
- Department of Surgery, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Alvin C. Powers
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232
- VA Tennessee Valley Healthcare System, Nashville, TN 37232
| | - Wen-hong Li
- Departments of Cell Biology and of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390-9039
| | - Lea K. Davis
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Jamey D. Young
- Department of Chemical and Biomolecular Engineering, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Richard M. O’Brien
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
- To whom correspondence should be addressed: Department of Molecular Physiology and Biophysics, 8415 MRB IV, 2213 Garland Ave, Vanderbilt University Medical School, Nashville, TN 37232-0615,
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19
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Veiga‐da‐Cunha M, Van Schaftingen E, Bommer GT. Inborn errors of metabolite repair. J Inherit Metab Dis 2020; 43:14-24. [PMID: 31691304 PMCID: PMC7041631 DOI: 10.1002/jimd.12187] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 10/18/2019] [Accepted: 11/04/2019] [Indexed: 12/11/2022]
Abstract
It is traditionally assumed that enzymes of intermediary metabolism are extremely specific and that this is sufficient to prevent the production of useless and/or toxic side-products. Recent work indicates that this statement is not entirely correct. In reality, enzymes are not strictly specific, they often display weak side activities on intracellular metabolites (substrate promiscuity) that resemble their physiological substrate or slowly catalyse abnormal reactions on their physiological substrate (catalytic promiscuity). They thereby produce non-classical metabolites that are not efficiently metabolised by conventional enzymes. In an increasing number of cases, metabolite repair enzymes are being discovered that serve to eliminate these non-classical metabolites and prevent their accumulation. Metabolite repair enzymes also eliminate non-classical metabolites that are formed through spontaneous (ie, not enzyme-catalysed) reactions. Importantly, genetic deficiencies in several metabolite repair enzymes lead to 'inborn errors of metabolite repair', such as L-2-hydroxyglutaric aciduria, D-2-hydroxyglutaric aciduria, 'ubiquitous glucose-6-phosphatase' (G6PC3) deficiency, the neutropenia present in Glycogen Storage Disease type Ib or defects in the enzymes that repair the hydrated forms of NADH or NADPH. Metabolite repair defects may be difficult to identify as such, because the mutated enzymes are non-classical enzymes that act on non-classical metabolites, which in some cases accumulate only inside the cells, and at rather low, yet toxic, concentrations. It is therefore likely that many additional metabolite repair enzymes remain to be discovered and that many diseases of metabolite repair still await elucidation.
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Affiliation(s)
| | - Emile Van Schaftingen
- de Duve InstituteUniversité Catholique de Louvain (UCLouvain)BrusselsBelgium
- Walloon Excellence in Life Sciences and Biotechnology (WELBIO)UCLouvainBrusselsBelgium
| | - Guido T. Bommer
- de Duve InstituteUniversité Catholique de Louvain (UCLouvain)BrusselsBelgium
- Walloon Excellence in Life Sciences and Biotechnology (WELBIO)UCLouvainBrusselsBelgium
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20
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Bolton C, Burch N, Morgan J, Harrison B, Pandey S, Pagnamenta AT, Taylor JC, Taylor JM, Marsh JCW, Potter V, Travis S, Uhlig HH. Remission of Inflammatory Bowel Disease in Glucose-6-Phosphatase 3 Deficiency by Allogeneic Haematopoietic Stem Cell Transplantation. J Crohns Colitis 2020; 14:142-147. [PMID: 31157858 PMCID: PMC6930000 DOI: 10.1093/ecco-jcc/jjz112] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Mendelian disorders in glucose-6-phosphate metabolism can present with inflammatory bowel disease [IBD]. Using whole genome sequencing we identified a homozygous variant in the glucose-6-phosphatase G6PC3 gene [c.911dupC; p.Q305fs*82] in an adult patient with congenital neutropenia, lymphopenia and childhood-onset, therapy-refractory Crohn's disease. Because G6PC3 is expressed in several haematopoietic and non-haematopoietic cells it was unclear whether allogeneic stem cell transplantation [HSCT] would benefit this patient with intestinal inflammation. We show that HSCT resolves G6PC3-associated immunodeficiency and the Crohn's disease phenotype. It illustrates how even in adulthood, next-generation sequencing can have a significant impact on clinical practice and healthcare utilization in patients with immunodeficiency and monogenic IBD.
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Affiliation(s)
- Chrissy Bolton
- Translational Gastroenterology Unit, NIHR Oxford Biomedical Research Centre, Nuffield Department of Experimental Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Nicola Burch
- University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK
| | - James Morgan
- University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK
| | - Beth Harrison
- University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK
| | - Sumeet Pandey
- Translational Gastroenterology Unit, NIHR Oxford Biomedical Research Centre, Nuffield Department of Experimental Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Alistair T Pagnamenta
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK,Oxford NIHR Biomedical Research Centre, Oxford, UK
| | | | - Jenny C Taylor
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK,Oxford NIHR Biomedical Research Centre, Oxford, UK
| | - John M Taylor
- Oxford NIHR Biomedical Research Centre, Oxford, UK,Oxford Medical Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Judith C W Marsh
- Department of Haematological Medicine, King’s College Hospital/King’s College London, London, UK
| | - Victoria Potter
- Department of Haematological Medicine, King’s College Hospital/King’s College London, London, UK
| | - Simon Travis
- Translational Gastroenterology Unit, NIHR Oxford Biomedical Research Centre, Nuffield Department of Experimental Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK,Oxford NIHR Biomedical Research Centre, Oxford, UK
| | - Holm H Uhlig
- Translational Gastroenterology Unit, NIHR Oxford Biomedical Research Centre, Nuffield Department of Experimental Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK,Oxford NIHR Biomedical Research Centre, Oxford, UK,Department of Paediatrics, University of Oxford, John Radcliffe Hospital, Oxford, UK,Corresponding author: Holm H. Uhlig, Translational Gastroenterology Unit, NIHR Oxford Biomedical Research Centre, Nuffield Department of Experimental Medicine and Department of Paediatrics, John Radcliffe Hospital, University of Oxford, Oxford, UK. Tel.: 0044 1865 8 57963; E-mail:
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21
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Sim SW, Weinstein DA, Lee YM, Jun HS. Glycogen storage disease type Ib: role of glucose‐6‐phosphate transporter in cell metabolism and function. FEBS Lett 2019; 594:3-18. [DOI: 10.1002/1873-3468.13666] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 10/16/2019] [Accepted: 10/25/2019] [Indexed: 12/19/2022]
Affiliation(s)
- Sang Wan Sim
- Department of Biotechnology and Bioinformatics College of Science and Technology Korea University Sejong Korea
| | - David A. Weinstein
- Glycogen Storage Disease Program University of Connecticut School of Medicine Farmington CT USA
| | - Young Mok Lee
- Glycogen Storage Disease Program University of Connecticut School of Medicine Farmington CT USA
| | - Hyun Sik Jun
- Department of Biotechnology and Bioinformatics College of Science and Technology Korea University Sejong Korea
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22
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Mutational spectrum and identification of five novel mutations in G6PC1 gene from a cohort of Glycogen Storage Disease Type 1a. Gene 2019; 700:7-16. [DOI: 10.1016/j.gene.2019.03.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 03/15/2019] [Accepted: 03/15/2019] [Indexed: 12/11/2022]
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23
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CRISPR/Cas9 genome editing of SLC37A4 gene elucidates the role of molecular markers of endoplasmic reticulum stress and apoptosis in renal involvement in glycogen storage disease type Ib. Gene 2019; 703:17-25. [DOI: 10.1016/j.gene.2019.04.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Revised: 03/29/2019] [Accepted: 04/01/2019] [Indexed: 12/11/2022]
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24
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Failure to eliminate a phosphorylated glucose analog leads to neutropenia in patients with G6PT and G6PC3 deficiency. Proc Natl Acad Sci U S A 2019; 116:1241-1250. [PMID: 30626647 PMCID: PMC6347702 DOI: 10.1073/pnas.1816143116] [Citation(s) in RCA: 97] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Neutropenia presents an important clinical problem in patients with G6PC3 or G6PT deficiency, yet why neutropenia occurs is unclear. We discovered that G6PC3 and G6PT collaborate to dephosphorylate a noncanonical metabolite (1,5-anhydroglucitol-6-phosphate; 1,5AG6P) which is produced when glucose-phosphorylating enzymes erroneously act on 1,5-anhydroglucitol, a food-derived polyol present in blood. In patients or mice with G6PC3 or G6PT deficiency, 1,5AG6P accumulates and inhibits the first step of glycolysis. This is particularly detrimental in neutrophils, since their energy metabolism depends almost entirely on glycolysis. Consistent with our findings, we observed that treatment with a 1,5-anhydroglucitol-lowering drug treats neutropenia in G6PC3-deficient mice. Our findings highlight that the elimination of noncanonical side products by metabolite-repair enzymes makes an important contribution to mammalian physiology. Neutropenia represents an important problem in patients with genetic deficiency in either the glucose-6-phosphate transporter of the endoplasmic reticulum (G6PT/SLC37A4) or G6PC3, an endoplasmic reticulum phosphatase homologous to glucose-6-phosphatase. While affected granulocytes show reduced glucose utilization, the underlying mechanism is unknown and causal therapies are lacking. Using a combination of enzymological, cell-culture, and in vivo approaches, we demonstrate that G6PT and G6PC3 collaborate to destroy 1,5-anhydroglucitol-6-phosphate (1,5AG6P), a close structural analog of glucose-6-phosphate and an inhibitor of low-KM hexokinases, which catalyze the first step in glycolysis in most tissues. We show that 1,5AG6P is made by phosphorylation of 1,5-anhydroglucitol, a compound normally present in human plasma, by side activities of ADP-glucokinase and low-KM hexokinases. Granulocytes from patients deficient in G6PC3 or G6PT accumulate 1,5AG6P to concentrations (∼3 mM) that strongly inhibit hexokinase activity. In a model of G6PC3-deficient mouse neutrophils, physiological concentrations of 1,5-anhydroglucitol caused massive accumulation of 1,5AG6P, a decrease in glucose utilization, and cell death. Treating G6PC3-deficient mice with an inhibitor of the kidney glucose transporter SGLT2 to lower their blood level of 1,5-anhydroglucitol restored a normal neutrophil count, while administration of 1,5-anhydroglucitol had the opposite effect. In conclusion, we show that the neutropenia in patients with G6PC3 or G6PT mutations is a metabolite-repair deficiency, caused by a failure to eliminate the nonclassical metabolite 1,5AG6P.
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25
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Chou JY, Cho JH, Kim GY, Mansfield BC. Molecular biology and gene therapy for glycogen storage disease type Ib. J Inherit Metab Dis 2018; 41:1007-1014. [PMID: 29663270 DOI: 10.1007/s10545-018-0180-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 03/01/2018] [Accepted: 03/26/2018] [Indexed: 12/15/2022]
Abstract
Glycogen storage disease type Ib (GSD-Ib) is caused by a deficiency in the ubiquitously expressed glucose-6-phosphate (G6P) transporter (G6PT or SLC37A4). The primary function of G6PT is to translocate G6P from the cytoplasm into the lumen of the endoplasmic reticulum (ER). Inside the ER, G6P is hydrolyzed to glucose and phosphate by either the liver/kidney/intestine-restricted glucose-6-phosphatase-α (G6Pase-α) or the ubiquitously expressed G6Pase-β. A deficiency in G6Pase-α causes GSD type Ia (GSD-Ia) and a deficiency in G6Pase-β causes GSD-I-related syndrome (GSD-Irs). In gluconeogenic organs, functional coupling of G6PT and G6Pase-α is required to maintain interprandial blood glucose homeostasis. In myeloid tissues, functional coupling of G6PT and G6Pase-β is required to maintain neutrophil homeostasis. Accordingly, GSD-Ib is a metabolic and immune disorder, manifesting impaired glucose homeostasis, neutropenia, and neutrophil dysfunction. A G6pt knockout mouse model is being exploited to delineate the pathophysiology of GSD-Ib and develop new clinical treatment options, including gene therapy. The safety and efficacy of several G6PT-expressing recombinant adeno-associated virus pseudotype 2/8 vectors have been examined in murine GSD-Ib. The results demonstrate that the liver-directed gene transfer and expression safely corrects metabolic abnormalities and prevents hepatocellular adenoma (HCA) development. However, a second vector system may be required to correct myeloid and renal dysfunction in GSD-Ib. These findings are paving the way to a safe and efficacious gene therapy for entering clinical trials.
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Affiliation(s)
- Janice Y Chou
- Section on Cellular Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Building 10, Room 8N240C, NIH 10 Center Drive, Bethesda, MD, 20892-1830, USA.
| | - Jun-Ho Cho
- Section on Cellular Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Building 10, Room 8N240C, NIH 10 Center Drive, Bethesda, MD, 20892-1830, USA
| | - Goo-Young Kim
- Section on Cellular Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Building 10, Room 8N240C, NIH 10 Center Drive, Bethesda, MD, 20892-1830, USA
| | - Brian C Mansfield
- Section on Cellular Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Building 10, Room 8N240C, NIH 10 Center Drive, Bethesda, MD, 20892-1830, USA
- Foundation Fighting Blindness, Columbia, MD, 21046, USA
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26
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Cappello AR, Curcio R, Lappano R, Maggiolini M, Dolce V. The Physiopathological Role of the Exchangers Belonging to the SLC37 Family. Front Chem 2018; 6:122. [PMID: 29719821 PMCID: PMC5913288 DOI: 10.3389/fchem.2018.00122] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Accepted: 03/30/2018] [Indexed: 12/14/2022] Open
Abstract
The human SLC37 gene family includes four proteins SLC37A1-4, localized in the endoplasmic reticulum (ER) membrane. They have been grouped into the SLC37 family due to their sequence homology to the bacterial organophosphate/phosphate (Pi) antiporter. SLC37A1-3 are the less characterized isoforms. SLC37A1 and SLC37A2 are Pi-linked glucose-6-phosphate (G6P) antiporters, catalyzing both homologous (Pi/Pi) and heterologous (G6P/Pi) exchanges, whereas SLC37A3 transport properties remain to be clarified. Furthermore, SLC37A1 is highly homologous to the bacterial glycerol 3-phosphate permeases, so it is supposed to transport also glycerol-3-phosphate. The physiological role of SLC37A1-3 is yet to be further investigated. SLC37A1 seems to be required for lipid biosynthesis in cancer cell lines, SLC37A2 has been proposed as a vitamin D and a phospho-progesterone receptor target gene, while mutations in the SLC37A3 gene appear to be associated with congenital hyperinsulinism of infancy. SLC37A4, also known as glucose-6-phosphate translocase (G6PT), transports G6P from the cytoplasm into the ER lumen, working in complex with either glucose-6-phosphatase-α (G6Pase-α) or G6Pase-β to hydrolyze intraluminal G6P to Pi and glucose. G6PT and G6Pase-β are ubiquitously expressed, whereas G6Pase-α is specifically expressed in the liver, kidney and intestine. G6PT/G6Pase-α complex activity regulates fasting blood glucose levels, whereas G6PT/G6Pase-β is required for neutrophil functions. G6PT deficiency is responsible for glycogen storage disease type Ib (GSD-Ib), an autosomal recessive disorder associated with both defective metabolic and myeloid phenotypes. Several kinds of mutations have been identified in the SLC37A4 gene, affecting G6PT function. An increased autoimmunity risk for GSD-Ib patients has also been reported, moreover, SLC37A4 seems to be involved in autophagy.
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Affiliation(s)
- Anna Rita Cappello
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Rende, Italy
| | - Rosita Curcio
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Rende, Italy
| | - Rosamaria Lappano
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Rende, Italy
| | - Marcello Maggiolini
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Rende, Italy
| | - Vincenza Dolce
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Rende, Italy
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27
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Hijmans BS, Boss A, van Dijk TH, Soty M, Wolters H, Mutel E, Groen AK, Derks TGJ, Mithieux G, Heerschap A, Reijngoud DJ, Rajas F, Oosterveer MH. Hepatocytes contribute to residual glucose production in a mouse model for glycogen storage disease type Ia. Hepatology 2017; 66:2042-2054. [PMID: 28727166 DOI: 10.1002/hep.29389] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 07/02/2017] [Accepted: 07/15/2017] [Indexed: 01/14/2023]
Abstract
UNLABELLED It is a long-standing enigma how glycogen storage disease (GSD) type I patients retain a limited capacity for endogenous glucose production despite the loss of glucose-6-phosphatase activity. Insight into the source of residual endogenous glucose production is of clinical importance given the risk of sudden death in these patients, but so far contradictory mechanisms have been proposed. We investigated glucose-6-phosphatase-independent endogenous glucose production in hepatocytes isolated from a liver-specific GSD Ia mouse model (L-G6pc-/- mice) and performed real-time analysis of hepatic glucose fluxes and glycogen metabolism in L-G6pc-/- mice using state-of-the-art stable isotope methodologies. Here we show that G6pc-deficient hepatocytes are capable of producing glucose. In vivo analysis of hepatic glucose metabolism revealed that the hepatic glucokinase flux was decreased by 95% in L-G6pc-/- mice. It also showed increased glycogen phosphorylase flux in L-G6pc-/- mice, which is coupled to the release of free glucose through glycogen debranching. Although the ex vivo activities of debranching enzyme and lysosomal acid maltase, two major hepatic α-glucosidases, were unaltered in L-G6pc-/- mice, pharmacological inhibition of α-glucosidase activity almost completely abolished residual glucose production by G6pc-deficient hepatocytes. CONCLUSION Our data indicate that hepatocytes contribute to residual glucose production in GSD Ia. We show that α-glucosidase activity, i.e. glycogen debranching and/or lysosomal glycogen breakdown, contributes to residual glucose production by GSD Ia hepatocytes. A strong reduction in hepatic GCK flux in L-G6pc-/- mice furthermore limits the phosphorylation of free glucose synthesized by G6pc-deficient hepatocytes, allowing the release of glucose into the circulation. The almost complete abrogation of GCK flux in G6pc-deficient liver also explains the contradictory reports on residual glucose production in GSD Ia patients. (Hepatology 2017;66:2042-2054).
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Affiliation(s)
- Brenda S Hijmans
- Department of Pediatrics, Center for Liver Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Andreas Boss
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Theo H van Dijk
- Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Maud Soty
- Institut National de la Santé et de la Recherche Médicale U1213.,Université de Lyon, Lyon, France.,Université Lyon 1, Lyon, France
| | - Henk Wolters
- Department of Pediatrics, Center for Liver Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Elodie Mutel
- Institut National de la Santé et de la Recherche Médicale U1213.,Université de Lyon, Lyon, France.,Université Lyon 1, Lyon, France
| | - Albert K Groen
- Department of Pediatrics, Center for Liver Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.,Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Terry G J Derks
- Section of Metabolic Diseases, Beatrix Children's Hospital, Center for Liver Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Gilles Mithieux
- Institut National de la Santé et de la Recherche Médicale U1213.,Université de Lyon, Lyon, France.,Université Lyon 1, Lyon, France
| | - Arend Heerschap
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Dirk-Jan Reijngoud
- Department of Pediatrics, Center for Liver Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.,Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Fabienne Rajas
- Institut National de la Santé et de la Recherche Médicale U1213.,Université de Lyon, Lyon, France.,Université Lyon 1, Lyon, France
| | - Maaike H Oosterveer
- Department of Pediatrics, Center for Liver Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
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28
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Boortz KA, Syring KE, Pound LD, Mo H, Bastarache L, Oeser JK, McGuinness OP, Denny JC, O’Brien RM. Effects of G6pc2 deletion on body weight and cholesterol in mice. J Mol Endocrinol 2017; 58:127-139. [PMID: 28122818 PMCID: PMC5380368 DOI: 10.1530/jme-16-0202] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 01/24/2017] [Indexed: 11/08/2022]
Abstract
Genome-wide association study (GWAS) data have linked the G6PC2 gene to variations in fasting blood glucose (FBG). G6PC2 encodes an islet-specific glucose-6-phosphatase catalytic subunit that forms a substrate cycle with the beta cell glucose sensor glucokinase. This cycle modulates the glucose sensitivity of insulin secretion and hence FBG. GWAS data have not linked G6PC2 to variations in body weight but we previously reported that female C57BL/6J G6pc2-knockout (KO) mice were lighter than wild-type littermates on both a chow and high-fat diet. The purpose of this study was to compare the effects of G6pc2 deletion on FBG and body weight in both chow-fed and high-fat-fed mice on two other genetic backgrounds. FBG was reduced in G6pc2 KO mice largely independent of gender, genetic background or diet. In contrast, the effect of G6pc2 deletion on body weight was markedly influenced by these variables. Deletion of G6pc2 conferred a marked protection against diet-induced obesity in male mixed genetic background mice, whereas in 129SvEv mice deletion of G6pc2 had no effect on body weight. G6pc2 deletion also reduced plasma cholesterol levels in a manner dependent on gender, genetic background and diet. An association between G6PC2 and plasma cholesterol was also observed in humans through electronic health record-derived phenotype analyses. These observations suggest that the action of G6PC2 on FBG is largely independent of the influences of environment, modifier genes or epigenetic events, whereas the action of G6PC2 on body weight and cholesterol are influenced by unknown variables.
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Affiliation(s)
- Kayla A. Boortz
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Kristen E. Syring
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Lynley D. Pound
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Huan Mo
- Department of Biomedical Informatics, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Lisa Bastarache
- Department of Biomedical Informatics, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - James K. Oeser
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Owen P. McGuinness
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Joshua C. Denny
- Department of Biomedical Informatics, Vanderbilt University School of Medicine, Nashville, TN 37232
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Richard M. O’Brien
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
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29
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Hytönen MK, Arumilli M, Lappalainen AK, Owczarek-Lipska M, Jagannathan V, Hundi S, Salmela E, Venta P, Sarkiala E, Jokinen T, Gorgas D, Kere J, Nieminen P, Drögemüller C, Lohi H. Molecular Characterization of Three Canine Models of Human Rare Bone Diseases: Caffey, van den Ende-Gupta, and Raine Syndromes. PLoS Genet 2016; 12:e1006037. [PMID: 27187611 PMCID: PMC4871343 DOI: 10.1371/journal.pgen.1006037] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 04/18/2016] [Indexed: 12/03/2022] Open
Abstract
One to two percent of all children are born with a developmental disorder requiring pediatric hospital admissions. For many such syndromes, the molecular pathogenesis remains poorly characterized. Parallel developmental disorders in other species could provide complementary models for human rare diseases by uncovering new candidate genes, improving the understanding of the molecular mechanisms and opening possibilities for therapeutic trials. We performed various experiments, e.g. combined genome-wide association and next generation sequencing, to investigate the clinico-pathological features and genetic causes of three developmental syndromes in dogs, including craniomandibular osteopathy (CMO), a previously undescribed skeletal syndrome, and dental hypomineralization, for which we identified pathogenic variants in the canine SLC37A2 (truncating splicing enhancer variant), SCARF2 (truncating 2-bp deletion) and FAM20C (missense variant) genes, respectively. CMO is a clinical equivalent to an infantile cortical hyperostosis (Caffey disease), for which SLC37A2 is a new candidate gene. SLC37A2 is a poorly characterized member of a glucose-phosphate transporter family without previous disease associations. It is expressed in many tissues, including cells of the macrophage lineage, e.g. osteoclasts, and suggests a disease mechanism, in which an impaired glucose homeostasis in osteoclasts compromises their function in the developing bone, leading to hyperostosis. Mutations in SCARF2 and FAM20C have been associated with the human van den Ende-Gupta and Raine syndromes that include numerous features similar to the affected dogs. Given the growing interest in the molecular characterization and treatment of human rare diseases, our study presents three novel physiologically relevant models for further research and therapy approaches, while providing the molecular identity for the canine conditions. Rare developmental disorders make a major contribution to pediatric hospital admissions and mortality. There is a growing interest in the development of therapeutics for these conditions, but that requires understanding of the genetic cause and pathology. Research can be facilitated by physiologically relevant models, such as dogs with corresponding disorders. We have characterized the clinical features and genetic causes of three developmental syndromes in dogs, including craniomandibular osteopathy (CMO), a previously undescribed skeletal syndrome, and dental hypomineralization, for which we identified mutations in the canine SLC37A2, SCARF2 and FAM20C genes, respectively. CMO is a clinical equivalent to an infantile cortical hyperostosis (Caffey disease) for which SLC37A2 is a new candidate gene. SLC37A2 is a glucose-phosphate transporter in osteoclasts, and its defect suggests an impaired glucose homeostasis in developing bone, leading to hyperostosis. Mutations in the SCARF2 and FAM20C genes have been associated with the human van den Ende-Gupta and Raine syndromes. Our study provides molecular identity for the canine conditions and presents three novel physiologically relevant models of human rare diseases.
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Affiliation(s)
- Marjo K. Hytönen
- Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland
- Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- The Folkhälsan Institute of Genetics, Helsinki, Finland
| | - Meharji Arumilli
- Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland
- Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- The Folkhälsan Institute of Genetics, Helsinki, Finland
| | - Anu K. Lappalainen
- Department of Equine and Small Animal Medicine, University of Helsinki, Helsinki, Finland
| | | | - Vidhya Jagannathan
- Institute of Genetics, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Sruthi Hundi
- Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland
- Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- The Folkhälsan Institute of Genetics, Helsinki, Finland
| | - Elina Salmela
- Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland
- Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- The Folkhälsan Institute of Genetics, Helsinki, Finland
| | - Patrick Venta
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, United States of America
| | - Eva Sarkiala
- Department of Equine and Small Animal Medicine, University of Helsinki, Helsinki, Finland
| | - Tarja Jokinen
- Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland
- Department of Equine and Small Animal Medicine, University of Helsinki, Helsinki, Finland
| | - Daniela Gorgas
- Division of Clinical Radiology, Department of Clinical Veterinary Medicine, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Juha Kere
- Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- The Folkhälsan Institute of Genetics, Helsinki, Finland
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Pekka Nieminen
- Department of Oral and Maxillofacial Diseases, University of Helsinki, Helsinki, Finland
| | - Cord Drögemüller
- Institute of Genetics, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Hannes Lohi
- Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland
- Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- The Folkhälsan Institute of Genetics, Helsinki, Finland
- * E-mail:
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Chou JY, Jun HS, Mansfield BC. Type I glycogen storage diseases: disorders of the glucose-6-phosphatase/glucose-6-phosphate transporter complexes. J Inherit Metab Dis 2015; 38:511-9. [PMID: 25288127 DOI: 10.1007/s10545-014-9772-x] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Revised: 08/12/2014] [Accepted: 09/12/2014] [Indexed: 12/15/2022]
Abstract
Disorders of the glucose-6-phosphatase (G6Pase)/glucose-6-phosphate transporter (G6PT) complexes consist of three subtypes: glycogen storage disease type Ia (GSD-Ia), deficient in the liver/kidney/intestine-restricted G6Pase-α (or G6PC); GSD-Ib, deficient in a ubiquitously expressed G6PT (or SLC37A4); and G6Pase-β deficiency or severe congenital neutropenia syndrome type 4 (SCN4), deficient in the ubiquitously expressed G6Pase-β (or G6PC3). G6Pase-α and G6Pase-β are glucose-6-phosphate (G6P) hydrolases with active sites lying inside the endoplasmic reticulum (ER) lumen and as such are dependent upon the G6PT to translocate G6P from the cytoplasm into the lumen. The tissue expression profiles of the G6Pase enzymes dictate the disease's phenotype. A functional G6Pase-α/G6PT complex maintains interprandial glucose homeostasis, while a functional G6Pase-β/G6PT complex maintains neutrophil/macrophage energy homeostasis and functionality. G6Pase-β deficiency is not a glycogen storage disease but biochemically it is a GSD-I related syndrome (GSD-Irs). GSD-Ia and GSD-Ib patients manifest a common metabolic phenotype of impaired blood glucose homeostasis not shared by GSD-Irs. GSD-Ib and GSD-Irs patients manifest a common myeloid phenotype of neutropenia and neutrophil/macrophage dysfunction not shared by GSD-Ia. While a disruption of the activity of the G6Pase-α/G6PT complex readily explains why GSD-Ia and GSD-Ib patients exhibit impaired glucose homeostasis, the basis for neutropenia and myeloid dysfunction in GSD-Ib and GSD-Irs are only now starting to be understood. Animal models of all three disorders are now available and are being exploited to both delineate the disease more precisely and develop new treatment approaches, including gene therapy.
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Affiliation(s)
- Janice Y Chou
- Section on Cellular Differentiation, Program on Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20892, USA,
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31
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Lin SR, Pan CJ, Mansfield BC, Chou JY. Functional analysis of mutations in a severe congenital neutropenia syndrome caused by glucose-6-phosphatase-β deficiency. Mol Genet Metab 2015; 114:41-5. [PMID: 25492228 PMCID: PMC4794745 DOI: 10.1016/j.ymgme.2014.11.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 11/18/2014] [Accepted: 11/19/2014] [Indexed: 12/18/2022]
Abstract
Glucose-6-phosphatase-β (G6Pase-β or G6PC3) deficiency is characterized by neutropenia and dysfunction in both neutrophils and macrophages. G6Pase-β is an enzyme embedded in the endoplasmic reticulum membrane that catalyzes the hydrolysis of glucose-6-phosphate (G6P) to glucose and phosphate. To date, 33 separate G6PC3 mutations have been identified in G6Pase-β-deficient patients but only the p.R253H and p.G260R missense mutations have been characterized functionally for pathogenicity. Here we functionally characterize 16 of the 19 known missense mutations using a sensitive assay, based on a recombinant adenoviral vector-mediated expression system, to demonstrate pathogenicity. Fourteen missense mutations completely abolish G6Pase-β enzymatic activity while the p.S139I and p.R189Q mutations retain 49% and 45%, respectively of wild type G6Pase-β activity. A database of residual enzymatic activity retained by the G6Pase-β mutations will serve as a reference for evaluating genotype-phenotype relationships.
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Affiliation(s)
- Su Ru Lin
- Section on Cellular Differentiation, Program on Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Chi-Jiunn Pan
- Section on Cellular Differentiation, Program on Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Brian C Mansfield
- Section on Cellular Differentiation, Program on Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA; Foundation Fighting Blindness, Columbia, MD 21046, USA
| | - Janice Yang Chou
- Section on Cellular Differentiation, Program on Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
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Zheng BX, Lin Q, Li M, Jin Y. Three novel mutations of the G6PC gene identified in Chinese patients with glycogen storage disease type Ia. Eur J Pediatr 2015; 174:59-63. [PMID: 24980439 PMCID: PMC4289013 DOI: 10.1007/s00431-014-2354-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2014] [Revised: 05/23/2014] [Accepted: 05/26/2014] [Indexed: 11/17/2022]
Abstract
UNLABELLED Glycogen storage disease type Ia (GSDIa) is an autosomal recessively inherited disease characterized by poor tolerance to fasting, growth retardation, and hepatomegaly resulting from accumulation of glycogen and fat in the liver. Germline mutations of glucose-6-phosphatase (G6PC) gene have been identified as a cause of GSDIa. In this study, we performed mutation analysis in five Chinese GSDIa patients belonging to five unrelated families by direct DNA sequencing. All patients were clinically classified as GSDIa. Mutation analysis of the G6PC gene revealed that all patients carried biallelic G6PC mutations (p.Ile341Asn, p.Ala274Val, p.Phe80Ile, p.Gly118Asp, p.Arg83His, c.262delG, and c.648G>T). Of the seven different mutations identified, three were found to be novel. All of the novel mutations were missense (p.Ala274Val, p.Phe80Ile, and p.Gly118Asp). The c.262delG mutation which leads to a frame-shift and truncated forms of glucose-6-phosphatase was present in three unrelated patients (one homozygote and two heterozygotes). CONCLUSION By direct DNA sequencing, three novel G6PC variations were identified which expanded the G6PC mutation spectrum, and provided conclusive genetic evidences for the definitive diagnosis of the Chinese patients.
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Affiliation(s)
- Bi-Xia Zheng
- Nanjing Children's Hospital Affiliated to Nanjing Medical University, Nanjing, China,
| | - Qian Lin
- Nanjing Children’s Hospital Affiliated to Nanjing Medical University, Nanjing, China
| | - Mei Li
- Nanjing Children’s Hospital Affiliated to Nanjing Medical University, Nanjing, China
| | - Yu Jin
- Nanjing Children’s Hospital, Medical School of Nanjing University, Nanjing, China
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Santos BL, de Souza CF, Schuler‐Faccini L, Refosco L, Epifanio M, Nalin T, Vieira SM, Schwartz IV. Glycogen storage disease type I: clinical and laboratory profile. JORNAL DE PEDIATRIA (VERSÃO EM PORTUGUÊS) 2014. [DOI: 10.1016/j.jpedp.2014.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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Santos BL, Souza CFMD, Schuler-Faccini L, Refosco L, Epifanio M, Nalin T, Vieira SMG, Schwartz IVD. Glycogen storage disease type I: clinical and laboratory profile. J Pediatr (Rio J) 2014; 90:572-9. [PMID: 25019649 DOI: 10.1016/j.jped.2014.02.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Accepted: 02/28/2014] [Indexed: 12/13/2022] Open
Abstract
OBJECTIVES To characterize the clinical, laboratory, and anthropometric profile of a sample of Brazilian patients with glycogen storage disease type I managed at an outpatient referral clinic for inborn errors of metabolism. METHODS This was a cross-sectional outpatient study based on a convenience sampling strategy. Data on diagnosis, management, anthropometric parameters, and follow-up were assessed. RESULTS Twenty-one patients were included (median age 10 years, range 1-25 years), all using uncooked cornstarch therapy. Median age at diagnosis was 7 months (range, 1-132 months), and 19 patients underwent liver biopsy for diagnostic confirmation. Overweight, short stature, hepatomegaly, and liver nodules were present in 16 of 21, four of 21, nine of 14, and three of 14 patients, respectively. A correlation was found between height-for-age and BMI-for-age Z-scores (r=0.561; p=0.008). CONCLUSIONS Diagnosis of glycogen storage disease type I is delayed in Brazil. Most patients undergo liver biopsy for diagnostic confirmation, even though the combination of a characteristic clinical presentation and molecular methods can provide a definitive diagnosis in a less invasive manner. Obesity is a side effect of cornstarch therapy, and appears to be associated with growth in these patients.
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Affiliation(s)
- Berenice L Santos
- Post-Graduate Program in Child and Adolescent Health, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Carolina F M de Souza
- Medical Genetics Service, Hospital de Clínicas de Porto Alegre, Porto Alegre, RS, Brazil
| | - Lavinia Schuler-Faccini
- Post-Graduate Program in Child and Adolescent Health, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil; Medical Genetics Service, Hospital de Clínicas de Porto Alegre, Porto Alegre, RS, Brazil; Department of Genetics, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Lilia Refosco
- Medical Genetics Service, Hospital de Clínicas de Porto Alegre, Porto Alegre, RS, Brazil
| | - Matias Epifanio
- Pontifícia Universidade Católica do Rio Grande do Sul (PUC-RS), Porto Alegre, RS, Brazil; Hospital São Lucas, Porto Alegre, RS, Brazil
| | - Tatiele Nalin
- Post-Graduate Program in Genetics and Molecular Biology, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Sandra M G Vieira
- Medical Pediatric Service, Hospital de Clínicas de Porto Alegre, Porto Alegre, RS, Brazil; Post-Graduate Program in Gastroenterology Science and Hepatology, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Ida V D Schwartz
- Medical Genetics Service, Hospital de Clínicas de Porto Alegre, Porto Alegre, RS, Brazil; Department of Genetics, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil.
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Multi-tissue computational modeling analyzes pathophysiology of type 2 diabetes in MKR mice. PLoS One 2014; 9:e102319. [PMID: 25029527 PMCID: PMC4100879 DOI: 10.1371/journal.pone.0102319] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Accepted: 06/18/2014] [Indexed: 12/25/2022] Open
Abstract
Computational models using metabolic reconstructions for in silico simulation of metabolic disorders such as type 2 diabetes mellitus (T2DM) can provide a better understanding of disease pathophysiology and avoid high experimentation costs. There is a limited amount of computational work, using metabolic reconstructions, performed in this field for the better understanding of T2DM. In this study, a new algorithm for generating tissue-specific metabolic models is presented, along with the resulting multi-confidence level (MCL) multi-tissue model. The effect of T2DM on liver, muscle, and fat in MKR mice was first studied by microarray analysis and subsequently the changes in gene expression of frank T2DM MKR mice versus healthy mice were applied to the multi-tissue model to test the effect. Using the first multi-tissue genome-scale model of all metabolic pathways in T2DM, we found out that branched-chain amino acids' degradation and fatty acids oxidation pathway is downregulated in T2DM MKR mice. Microarray data showed low expression of genes in MKR mice versus healthy mice in the degradation of branched-chain amino acids and fatty-acid oxidation pathways. In addition, the flux balance analysis using the MCL multi-tissue model showed that the degradation pathways of branched-chain amino acid and fatty acid oxidation were significantly downregulated in MKR mice versus healthy mice. Validation of the model was performed using data derived from the literature regarding T2DM. Microarray data was used in conjunction with the model to predict fluxes of various other metabolic pathways in the T2DM mouse model and alterations in a number of pathways were detected. The Type 2 Diabetes MCL multi-tissue model may explain the high level of branched-chain amino acids and free fatty acids in plasma of Type 2 Diabetic subjects from a metabolic fluxes perspective.
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Abstract
Glycogen storage disease type Ib (GSD-Ib) is an autosomal-recessive syndrome characterized by neutropenia and impaired glucose homeostasis resulting from a deficiency in the glucose-6-phosphate (G6P) transporter (G6PT). The underlying cause of GSD-Ib neutropenia is an enhanced neutrophil apoptosis, but patients also manifest neutrophil dysfunction of unknown etiology. Previously, we showed G6PT interacts with the enzyme glucose-6-phosphatase-β (G6Pase-β) to regulate the availability of G6P/glucose in neutrophils. A deficiency in G6Pase-β activity in neutrophils impairs both their energy homeostasis and function. We now show that G6PT-deficient neutrophils from GSD-Ib patients are similarly impaired. Their energy impairment is characterized by decreased glucose uptake and reduced levels of intracellular G6P, lactate, adenosine triphosphate, and reduced NAD phosphate, whereas functional impairment is reflected in reduced neutrophil respiratory burst, chemotaxis, and calcium mobilization. We further show that the mechanism of neutrophil dysfunction in GSD-Ib arises from activation of the hypoxia-inducible factor-1α/peroxisome-proliferators-activated receptor-γ pathway.
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Abstract
The SLC37 family members are endoplasmic reticulum (ER)-associated sugar-phosphate/phosphate (P(i)) exchangers. Three of the four members, SLC37A1, SLC37A2, and SLC37A4, function as Pi-linked glucose-6-phosphate (G6P) antiporters catalyzing G6P:P(i) and P(i):P(i) exchanges. The activity of SLC37A3 is unknown. SLC37A4, better known as the G6P transporter (G6PT), has been extensively characterized, functionally and structurally, and is the best characterized family member. G6PT contains 10 transmembrane helices with both N and C termini facing the cytoplasm. The primary in vivo function of the G6PT protein is to translocate G6P from the cytoplasm into the ER lumen where it couples with either the liver/kidney/intestine-restricted glucose-6-phosphatase-α (G6Pase-α or G6PC) or the ubiquitously expressed G6Pase-β (or G6PC3) to hydrolyze G6P to glucose and P(i). The G6PT/G6Pase-α complex maintains interprandial glucose homeostasis, and the G6PT/G6Pase-β complex maintains neutrophil energy homeostasis and functionality. G6PT is highly selective for G6P and is competitively inhibited by cholorogenic acid and its derivatives. Neither SLC37A1 nor SLC37A2 can couple functionally with G6Pase-α or G6Pase-β, and the antiporter activities of SLC37A1 or SLC37A2 are not inhibited by cholorogenic acid. Deficiencies in G6PT cause glycogen storage disease type Ib (GSD-Ib), a metabolic and immune disorder. To date, 91 separate SLC37A4 mutations, including 39 missense mutations, have been identified in GSD-Ib patients. Characterization of missense mutations has yielded valuable information on functionally important residues in the G6PT protein. The biological roles of the other SLC37 proteins remain to be determined and deficiencies have not yet been correlated to diseases.
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Affiliation(s)
- Janice Y Chou
- Section on Cellular Differentiation, Program on Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA.
| | - Brian C Mansfield
- Section on Cellular Differentiation, Program on Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA; Foundation Fighting Blindness, Columbia, Maryland, USA
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Adeva M, González-Lucán M, Seco M, Donapetry C. Enzymes involved in l-lactate metabolism in humans. Mitochondrion 2013; 13:615-29. [DOI: 10.1016/j.mito.2013.08.011] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 07/29/2013] [Accepted: 08/30/2013] [Indexed: 12/20/2022]
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39
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Chou JY, Sik Jun H, Mansfield BC. The SLC37 family of phosphate-linked sugar phosphate antiporters. Mol Aspects Med 2013; 34:601-11. [PMID: 23506893 DOI: 10.1016/j.mam.2012.05.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Accepted: 03/08/2012] [Indexed: 12/28/2022]
Abstract
The SLC37 family consists of four sugar-phosphate exchangers, A1, A2, A3, and A4, which are anchored in the endoplasmic reticulum (ER) membrane. The best characterized family member is SLC37A4, better known as the glucose-6-phosphate (G6P) transporter (G6PT). SLC37A1, SLC37A2, and G6PT function as phosphate (Pi)-linked G6P antiporters catalyzing G6P:Pi and Pi:Pi exchanges. The activity of SLC37A3 is unknown. G6PT translocates G6P from the cytoplasm into the lumen of the ER where it couples with either glucose-6-phosphatase-α (G6Pase-α) or G6Pase-β to hydrolyze intraluminal G6P to glucose and Pi. The functional coupling of G6PT with G6Pase-α maintains interprandial glucose homeostasis and the functional coupling of G6PT with G6Pase-β maintains neutrophil energy homeostasis and functionality. A deficiency in G6PT causes glycogen storage disease type Ib, an autosomal recessive disorder characterized by impaired glucose homeostasis, neutropenia, and neutrophil dysfunction. Neither SLC37A1 nor SLC37A2 can functionally couple with G6Pase-α or G6Pase-β, and there are no known disease associations for them or SLC37A3. Since only G6PT matches the characteristics of the physiological ER G6P transporter involved in blood glucose homeostasis and neutrophil energy metabolism, the biological roles for the other SLC37 proteins remain to be determined.
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Affiliation(s)
- Janice Y Chou
- Section on Cellular Differentiation, Program on Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
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40
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Banka S, Newman WG. A clinical and molecular review of ubiquitous glucose-6-phosphatase deficiency caused by G6PC3 mutations. Orphanet J Rare Dis 2013; 8:84. [PMID: 23758768 PMCID: PMC3718741 DOI: 10.1186/1750-1172-8-84] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Accepted: 05/22/2013] [Indexed: 12/14/2022] Open
Abstract
The G6PC3 gene encodes the ubiquitously expressed glucose-6-phosphatase enzyme (G-6-Pase β or G-6-Pase 3 or G6PC3). Bi-allelic G6PC3 mutations cause a multi-system autosomal recessive disorder of G6PC3 deficiency (also called severe congenital neutropenia type 4, MIM 612541). To date, at least 57 patients with G6PC3 deficiency have been described in the literature. G6PC3 deficiency is characterized by severe congenital neutropenia, recurrent bacterial infections, intermittent thrombocytopenia in many patients, a prominent superficial venous pattern and a high incidence of congenital cardiac defects and uro-genital anomalies. The phenotypic spectrum of the condition is wide and includes rare manifestations such as maturation arrest of the myeloid lineage, a normocellular bone marrow, myelokathexis, lymphopaenia, thymic hypoplasia, inflammatory bowel disease, primary pulmonary hypertension, endocrine abnormalities, growth retardation, minor facial dysmorphism, skeletal and integument anomalies amongst others. Dursun syndrome is part of this extended spectrum. G6PC3 deficiency can also result in isolated non-syndromic severe neutropenia. G6PC3 mutations in result in reduced enzyme activity, endoplasmic reticulum stress response, increased rates of apoptosis of affected cells and dysfunction of neutrophil activity. In this review we demonstrate that loss of function in missense G6PC3 mutations likely results from decreased enzyme stability. The condition can be diagnosed by sequencing the G6PC3 gene. A number of G6PC3 founder mutations are known in various populations and a possible genotype-phenotype relationship also exists. G6PC3 deficiency should be considered as part of the differential diagnoses in any patient with unexplained congenital neutropenia. Treatment with G-CSF leads to improvement in neutrophil numbers, prevents infections and improves quality of life. Mildly affected patients can be managed with prophylactic antibiotics. Untreated G6PC3 deficiency can be fatal. Echocardiogram, renal and pelvic ultrasound scans should be performed in all cases of suspected or confirmed G6PC3 deficiency. Routine assessment should include biochemical profile, growth profile and monitoring for development of varicose veins or venous ulcers.
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Affiliation(s)
- Siddharth Banka
- Manchester Centre for Genomic Medicine, Institute of Human Development, University of Manchester, Manchester, UK.
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41
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Ontogenic Profile of Gluconeogenic Key Enzyme Gene Expressions in Embryonic Chicken Liver and Muscle. J Poult Sci 2013. [DOI: 10.2141/jpsa.0120183] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
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42
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Glucose-6-phosphatase-β, implicated in a congenital neutropenia syndrome, is essential for macrophage energy homeostasis and functionality. Blood 2012; 119:4047-55. [PMID: 22246029 DOI: 10.1182/blood-2011-09-377820] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Glucose-6-phosphatase-β (G6Pase-β or G6PC3) deficiency, also known as severe congenital neutropenia syndrome 4, is characterized not only by neutropenia but also by impaired neutrophil energy homeostasis and functionality. We now show the syndrome is also associated with macrophage dysfunction, with murine G6pc3(-/-) macrophages having impairments in their respiratory burst, chemotaxis, calcium flux, and phagocytic activities. Consistent with a glucose-6-phosphate (G6P) metabolism deficiency, G6pc3(-/-) macrophages also have a lower glucose uptake and lower levels of G6P, lactate, and ATP than wild-type macrophages. Furthermore, the expression of NADPH oxidase subunits and membrane translocation of p47(phox) are down-regulated, and G6pc3(-/-) macrophages exhibit repressed trafficking in vivo both during an inflammatory response and in pregnancy. During pregnancy, the absence of G6Pase-β activity also leads to impaired energy homeostasis in the uterus and reduced fertility of G6pc3(-/-) mothers. Together these results show that immune deficiencies in this congenital neutropenia syndrome extend beyond neutrophil dysfunction.
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Pan CJ, Chen SY, Jun HS, Lin SR, Mansfield BC, Chou JY. SLC37A1 and SLC37A2 are phosphate-linked, glucose-6-phosphate antiporters. PLoS One 2011; 6:e23157. [PMID: 21949678 PMCID: PMC3176764 DOI: 10.1371/journal.pone.0023157] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Accepted: 07/07/2011] [Indexed: 11/25/2022] Open
Abstract
Blood glucose homeostasis between meals depends upon production of glucose within the endoplasmic reticulum (ER) of the liver and kidney by hydrolysis of glucose-6-phosphate (G6P) into glucose and phosphate (Pi). This reaction depends on coupling the G6P transporter (G6PT) with glucose-6-phosphatase-α (G6Pase-α). Only one G6PT, also known as SLC37A4, has been characterized, and it acts as a Pi-linked G6P antiporter. The other three SLC37 family members, predicted to be sugar-phosphate:Pi exchangers, have not been characterized functionally. Using reconstituted proteoliposomes, we examine the antiporter activity of the other SLC37 members along with their ability to couple with G6Pase-α. G6PT- and mock-proteoliposomes are used as positive and negative controls, respectively. We show that SLC37A1 and SLC37A2 are ER-associated, Pi-linked antiporters, that can transport G6P. Unlike G6PT, neither is sensitive to chlorogenic acid, a competitive inhibitor of physiological ER G6P transport, and neither couples to G6Pase-α. We conclude that three of the four SLC37 family members are functional sugar-phosphate antiporters. However, only G6PT/SLC37A4 matches the characteristics of the physiological ER G6P transporter, suggesting the other SLC37 proteins have roles independent of blood glucose homeostasis.
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Affiliation(s)
- Chi-Jiunn Pan
- Section on Cellular Differentiation, Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Shih-Yin Chen
- Section on Cellular Differentiation, Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Hyun Sik Jun
- Section on Cellular Differentiation, Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Su Ru Lin
- Section on Cellular Differentiation, Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Brian C. Mansfield
- Section on Cellular Differentiation, Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Janice Y. Chou
- Section on Cellular Differentiation, Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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44
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Bennett KA, Forsyth L, Burchell A. Functional analysis of the 5' flanking region of the human G6PC3 gene: regulation of promoter activity by glucose, pyruvate, AMP kinase and the pentose phosphate pathway. Mol Genet Metab 2011; 103:254-61. [PMID: 21474354 DOI: 10.1016/j.ymgme.2011.03.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Revised: 03/11/2011] [Accepted: 03/11/2011] [Indexed: 10/18/2022]
Abstract
G6PC3 is a widely expressed isoform of glucose-6-phosphatase, found in many foetal and adult tissues. Mutations in this gene cause developmental abnormalities and severe neutropenia due to abolition of glucose recycling between the cytoplasm and endoplasmic reticulum. Low G6PC3 expression as a result of promoter polymorphisms or dysregulation could produce similar outcomes. Here we investigated the regulation of human G6PC3 promoter activity. HeLa and H4IIE cells were transiently transfected with G6PC3 promoter coupled to the firefly luciferase gene, and promoter activity was measured by dual luciferase assay. Activity was highest in a 453 bp segment of the G6PC3 promoter, from -455 to -3 relative to the transcriptional start site. This promoter was unresponsive to glucostatic hormones. Its activity increased significantly between 1 and 5.5 mM glucose, and was not elevated further by glucose concentrations up to 25 mM. Pyruvate increased its activity, but β-hydroxybutyrate and sodium acetate did not. Promoter activity was reduced by inhibitors of hexokinase, glyceraldehyde phosphate dehydrogenase and the oxidative branch of the pentose phosphate pathway, but not by a transketolase inhibitor. Deletion of two adjacent Enhancer-boxes (-274 to -279 and -299 to -304) reduced promoter activity and abolished the glucose effect, suggesting they could function as a glucose response element. Deletion of an additional downstream 140 bp (-140 to -306) restored activity, but not the glucose response, suggesting the presence of repressor elements in this region. 5-Aminoimidazole-4-carboxamide 1-β-D-ribofuranoside (AICAR) reduced promoter activity, showing dependence on AMP-kinase. Regulation of the G6PC3 promoter is thus radically different to that of the hepatic isoform, G6PC. It is sensitive to carbohydrate, but not to fatty acid metabolites, and at much lower physiological concentrations. Based on these findings, we speculate that reduced G6PC3 expression could occur during hypoglycemic episodes in vivo, which are common in utero and in the postnatal period. If such episodes lower G6PC3 expression they could place the foetus or infant at risk of impaired immune function and development, and this possibility requires further examination both in vitro and in vivo.
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Affiliation(s)
- Kimberley Ann Bennett
- Maternal and Child Health Sciences, Ninewells Hospital and Medical School, University of Dundee, Dundee, DD1 9SY, UK.
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Klein C. Genetic defects in severe congenital neutropenia: emerging insights into life and death of human neutrophil granulocytes. Annu Rev Immunol 2011; 29:399-413. [PMID: 21219176 DOI: 10.1146/annurev-immunol-030409-101259] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The discovery of genetic defects causing congenital neutropenia has illuminated mechanisms controlling differentiation, circulation, and decay of neutrophil granulocytes. Deficiency of the mitochondrial proteins HAX1 and AK2 cause premature apoptosis of myeloid progenitor cells associated with dissipation of the mitochondrial membrane potential, whereas mutations in ELA2/ELANE and G6PC3 are associated with signs of increased endoplasmic reticulum stress. Mutations in the transcriptional repressor GFI1 and the cytoskeletal regulator WASP also lead to defective neutrophil production. This unexpected diversity of factors suggests that multiple pathways are involved in the pathogenesis of congenital neutropenia.
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Affiliation(s)
- Christoph Klein
- Department of Pediatric Hematology/Oncology, Hannover Medical School, Germany.
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Bhattacharya K. Dietary dilemmas in the management of glycogen storage disease type I. J Inherit Metab Dis 2011; 34:621-9. [PMID: 21491105 DOI: 10.1007/s10545-011-9322-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Revised: 03/16/2011] [Accepted: 03/21/2011] [Indexed: 10/18/2022]
Abstract
Over the last 50 years, understanding the biochemical bases of glycogen storage disease type I has led to vastly improved survival and health outcomes but the management still centres around an extremely intensive dietary regimen. Patients' metabolic profiles are really determined by the whole of the diet and it can be very difficult to adjust therapy accordingly. In an iso-energetic diet with reference total energy intake, high carbohydrate intake could compromise other macro- and micro-nutrients; if carbohydrates are not restricted then total energy intake is excessive. The quality of the macronutrient such as the glycemic index of carbohydrate, the type of sugar and the proportion of medium-chain triglyceride and essential fatty acids also has a bearing on an individual's long-term metabolic control with potential clinical correlates. These factors as well as the different requirements between individuals and within individuals as they get older mean that the management of glycogen storage disease type I is particularly fraught. Regular clinical and dietary review is imperative as patients grow, ensuring adequate but not excessive low glycaemic index carbohydrate intake, appropriate dynamic biochemical profiles and suitable age appropriate eating patterns. Without diligent management, and education that empowers the patient, these individuals can struggle in adult life.
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Froissart R, Piraud M, Boudjemline AM, Vianey-Saban C, Petit F, Hubert-Buron A, Eberschweiler PT, Gajdos V, Labrune P. Glucose-6-phosphatase deficiency. Orphanet J Rare Dis 2011; 6:27. [PMID: 21599942 PMCID: PMC3118311 DOI: 10.1186/1750-1172-6-27] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Accepted: 05/20/2011] [Indexed: 01/01/2023] Open
Abstract
Glucose-6-phosphatase deficiency (G6P deficiency), or glycogen storage disease type I (GSDI), is a group of inherited metabolic diseases, including types Ia and Ib, characterized by poor tolerance to fasting, growth retardation and hepatomegaly resulting from accumulation of glycogen and fat in the liver. Prevalence is unknown and annual incidence is around 1/100,000 births. GSDIa is the more frequent type, representing about 80% of GSDI patients. The disease commonly manifests, between the ages of 3 to 4 months by symptoms of hypoglycemia (tremors, seizures, cyanosis, apnea). Patients have poor tolerance to fasting, marked hepatomegaly, growth retardation (small stature and delayed puberty), generally improved by an appropriate diet, osteopenia and sometimes osteoporosis, full-cheeked round face, enlarged kydneys and platelet dysfunctions leading to frequent epistaxis. In addition, in GSDIb, neutropenia and neutrophil dysfunction are responsible for tendency towards infections, relapsing aphtous gingivostomatitis, and inflammatory bowel disease. Late complications are hepatic (adenomas with rare but possible transformation into hepatocarcinoma) and renal (glomerular hyperfiltration leading to proteinuria and sometimes to renal insufficiency). GSDI is caused by a dysfunction in the G6P system, a key step in the regulation of glycemia. The deficit concerns the catalytic subunit G6P-alpha (type Ia) which is restricted to expression in the liver, kidney and intestine, or the ubiquitously expressed G6P transporter (type Ib). Mutations in the genes G6PC (17q21) and SLC37A4 (11q23) respectively cause GSDIa and Ib. Many mutations have been identified in both genes,. Transmission is autosomal recessive. Diagnosis is based on clinical presentation, on abnormal basal values and absence of hyperglycemic response to glucagon. It can be confirmed by demonstrating a deficient activity of a G6P system component in a liver biopsy. To date, the diagnosis is most commonly confirmed by G6PC (GSDIa) or SLC37A4 (GSDIb) gene analysis, and the indications of liver biopsy to measure G6P activity are getting rarer and rarer. Differential diagnoses include the other GSDs, in particular type III (see this term). However, in GSDIII, glycemia and lactacidemia are high after a meal and low after a fast period (often with a later occurrence than that of type I). Primary liver tumors and Pepper syndrome (hepatic metastases of neuroblastoma) may be evoked but are easily ruled out through clinical and ultrasound data. Antenatal diagnosis is possible through molecular analysis of amniocytes or chorionic villous cells. Pre-implantatory genetic diagnosis may also be discussed. Genetic counseling should be offered to patients and their families. The dietary treatment aims at avoiding hypoglycemia (frequent meals, nocturnal enteral feeding through a nasogastric tube, and later oral addition of uncooked starch) and acidosis (restricted fructose and galactose intake). Liver transplantation, performed on the basis of poor metabolic control and/or hepatocarcinoma, corrects hypoglycemia, but renal involvement may continue to progress and neutropenia is not always corrected in type Ib. Kidney transplantation can be performed in case of severe renal insufficiency. Combined liver-kidney grafts have been performed in a few cases. Prognosis is usually good: late hepatic and renal complications may occur, however, with adapted management, patients have almost normal life span. DISEASE NAME AND SYNONYMS: Glucose-6-phosphatase deficiency or G6P deficiency or glycogen storage disease type I or GSDI or type I glycogenosis or Von Gierke disease or Hepatorenal glycogenosis.
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Affiliation(s)
- Roseline Froissart
- Centre de Référence Maladies Héréditaires du Métabolisme Hépatique, Service de Pédiatrie, APHP, Clamart cedex, France
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G-CSF improves murine G6PC3-deficient neutrophil function by modulating apoptosis and energy homeostasis. Blood 2011; 117:3881-92. [PMID: 21292774 DOI: 10.1182/blood-2010-08-302059] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
G6PC3 (or glucose-6-phosphatase-β) deficiency underlies a congenital neutropenia syndrome in which neutrophils exhibit enhanced endoplasmic reticulum (ER) stress, increased apoptosis, impaired energy homeostasis, and impaired functionality. Here we show that murine G6pc3(-/-) neutrophils undergoing ER stress activate protein kinase-like ER kinase and phosphatidylinositol 3,4,5-trisphosphate/Akt signaling pathways, and that neutrophil apoptosis is mediated in part by the intrinsic mitochondrial pathway. In G6PC3-deficient patients, granulocyte colony-stimulating factor (G-CSF) improves neutropenia, but its impact on neutrophil apoptosis and dysfunction is unknown. We now show that G-CSF delays neutrophil apoptosis in vitro by modulating apoptotic mediators. However, G6pc3(-/-) neutrophils in culture exhibit accelerated apoptosis compared with wild-type neutrophils both in the presence or absence of G-CSF. Limiting glucose (0.6mM) accelerates apoptosis but is more pronounced for wild-type neutrophils, leading to similar survival profiles for both neutrophil populations. In vivo G-CSF therapy completely corrects neutropenia and normalizes levels of p-Akt, phosphatidylinositol 3,4,5-trisphosphate, and active caspase-3. Neutrophils from in vivo G-CSF-treated G6pc3(-/-) mice exhibit increased glucose uptake and elevated intracellular levels of G6P, lactate, and adenosine-5'-triphosphate, leading to improved functionality. Together, the results strongly suggest that G-CSF improves G6pc3(-/-) neutrophil survival by modulating apoptotic mediators and rectifies function by enhancing energy homeostasis.
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Boudjemline AM, Isapof A, Witas JB, Petit FM, Gajdos V, Labrune P. Klüver Bucy syndrome following hypoglycaemic coma in a patient with glycogen storage disease type Ib. J Inherit Metab Dis 2010; 33 Suppl 3:S477-80. [PMID: 21103936 DOI: 10.1007/s10545-010-9243-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Revised: 09/27/2010] [Accepted: 10/20/2010] [Indexed: 10/18/2022]
Abstract
Patients with type I glycogen storage disease (GSD) have poor tolerance to fasting, sometimes less than 3 hours during infancy. Even though most patients are able, as they get older, to tolerate a longer fasting period, they are at permanent risk for fast-induced hypoglycaemia, even in adulthood. Klüver Bucy syndrome, is characterized by psychic blindness (inability to recognize familiar objects), hypermetamorphosis (strong tendency to react to visual stimulus), increased oral exploration, placidity, indiscriminate hyper-sexuality and change in dietary habits. In this case report, we describe the development of Klüver Bucy syndrome in a 28-year-old man with type Ib GSD, following prolonged and severe hypoglycaemia triggered by a common respiratory infection.
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Abstract
Glycogen storage disease type I (GSD-I) consists of two subtypes: GSD-Ia, a deficiency in glucose-6-phosphatase-α (G6Pase-α) and GSD-Ib, which is characterized by an absence of a glucose-6-phosphate (G6P) transporter (G6PT). A third disorder, G6Pase-β deficiency, shares similarities with this group of diseases. G6Pase-α and G6Pase-β are G6P hydrolases in the membrane of the endoplasmic reticulum, which depend on G6PT to transport G6P from the cytoplasm into the lumen. A functional complex of G6PT and G6Pase-α maintains interprandial glucose homeostasis, whereas G6PT and G6Pase-β act in conjunction to maintain neutrophil function and homeostasis. Patients with GSD-Ia and those with GSD-Ib exhibit a common metabolic phenotype of disturbed glucose homeostasis that is not evident in patients with G6Pase-β deficiency. Patients with a deficiency in G6PT and those lacking G6Pase-β display a common myeloid phenotype that is not shared by patients with GSD-Ia. Previous studies have shown that neutrophils express the complex of G6PT and G6Pase-β to produce endogenous glucose. Inactivation of either G6PT or G6Pase-β increases neutrophil apoptosis, which underlies, at least in part, neutrophil loss (neutropenia) and dysfunction in GSD-Ib and G6Pase-β deficiency. Dietary and/or granulocyte colony-stimulating factor therapies are available; however, many aspects of the diseases are still poorly understood. This Review will address the etiology of GSD-Ia, GSD-Ib and G6Pase-β deficiency and highlight advances in diagnosis and new treatment approaches, including gene therapy.
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Affiliation(s)
- Janice Y Chou
- Section on Cellular Differentiation, Program on Developmental Endocrinology and Genetics, Building 10, Room 9D42, 10 Center Drive, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-1830, USA.
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