1
|
Pascoal C, Francisco R, Ferro T, Dos Reis Ferreira V, Jaeken J, Videira PA. CDG and immune response: From bedside to bench and back. J Inherit Metab Dis 2020; 43:90-124. [PMID: 31095764 DOI: 10.1002/jimd.12126] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 05/13/2019] [Accepted: 05/15/2019] [Indexed: 12/20/2022]
Abstract
Glycosylation is an essential biological process that adds structural and functional diversity to cells and molecules, participating in physiological processes such as immunity. The immune response is driven and modulated by protein-attached glycans that mediate cell-cell interactions, pathogen recognition and cell activation. Therefore, abnormal glycosylation can be associated with deranged immune responses. Within human diseases presenting immunological defects are congenital disorders of glycosylation (CDG), a family of around 130 rare and complex genetic diseases. In this review, we have identified 23 CDG with immunological involvement, characterized by an increased propensity to-often life-threatening-infection. Inflammatory and autoimmune complications were found in 7 CDG types. CDG natural history(ies) and the mechanisms behind the immunological anomalies are still poorly understood. However, in some cases, alterations in pathogen recognition and intracellular signaling (eg, TGF-β1, NFAT, and NF-κB) have been suggested. Targeted therapies to restore immune defects are only available for PGM3-CDG and SLC35C1-CDG. Fostering research on glycoimmunology may elucidate the involved pathophysiological mechanisms and open new therapeutic avenues, thus improving CDG patients' quality of life.
Collapse
Affiliation(s)
- Carlota Pascoal
- Portuguese Association for CDG, Lisbon, Portugal
- CDG & Allies - Professionals and Patient Associations International Network (CDG & Allies - PPAIN), Caparica, Portugal
- UCIBIO, Departamento Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Caparica, Portugal
| | - Rita Francisco
- Portuguese Association for CDG, Lisbon, Portugal
- CDG & Allies - Professionals and Patient Associations International Network (CDG & Allies - PPAIN), Caparica, Portugal
- UCIBIO, Departamento Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Caparica, Portugal
| | - Tiago Ferro
- CDG & Allies - Professionals and Patient Associations International Network (CDG & Allies - PPAIN), Caparica, Portugal
- UCIBIO, Departamento Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Caparica, Portugal
| | - Vanessa Dos Reis Ferreira
- Portuguese Association for CDG, Lisbon, Portugal
- CDG & Allies - Professionals and Patient Associations International Network (CDG & Allies - PPAIN), Caparica, Portugal
| | - Jaak Jaeken
- CDG & Allies - Professionals and Patient Associations International Network (CDG & Allies - PPAIN), Caparica, Portugal
- Center for Metabolic Diseases, Department of Development and Regeneration, UZ and KU Leuven, Leuven, Belgium
| | - Paula A Videira
- Portuguese Association for CDG, Lisbon, Portugal
- CDG & Allies - Professionals and Patient Associations International Network (CDG & Allies - PPAIN), Caparica, Portugal
- UCIBIO, Departamento Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Caparica, Portugal
| |
Collapse
|
2
|
Lizák B, Szarka A, Kim Y, Choi KS, Németh CE, Marcolongo P, Benedetti A, Bánhegyi G, Margittai É. Glucose Transport and Transporters in the Endomembranes. Int J Mol Sci 2019; 20:ijms20235898. [PMID: 31771288 PMCID: PMC6929180 DOI: 10.3390/ijms20235898] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 11/16/2019] [Accepted: 11/21/2019] [Indexed: 12/18/2022] Open
Abstract
Glucose is a basic nutrient in most of the creatures; its transport through biological membranes is an absolute requirement of life. This role is fulfilled by glucose transporters, mediating the transport of glucose by facilitated diffusion or by secondary active transport. GLUT (glucose transporter) or SLC2A (Solute carrier 2A) families represent the main glucose transporters in mammalian cells, originally described as plasma membrane transporters. Glucose transport through intracellular membranes has not been elucidated yet; however, glucose is formed in the lumen of various organelles. The glucose-6-phosphatase system catalyzing the last common step of gluconeogenesis and glycogenolysis generates glucose within the lumen of the endoplasmic reticulum. Posttranslational processing of the oligosaccharide moiety of glycoproteins also results in intraluminal glucose formation in the endoplasmic reticulum (ER) and Golgi. Autophagic degradation of polysaccharides, glycoproteins, and glycolipids leads to glucose accumulation in lysosomes. Despite the obvious necessity, the mechanism of glucose transport and the molecular nature of mediating proteins in the endomembranes have been hardly elucidated for the last few years. However, recent studies revealed the intracellular localization and functional features of some glucose transporters; the aim of the present paper was to summarize the collected knowledge.
Collapse
Affiliation(s)
- Beáta Lizák
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, 1094 Budapest, Hungary; (B.L.); (C.E.N.); (G.B.)
| | - András Szarka
- Laboratory of Biochemistry and Molecular Biology, Department of Applied Biotechnology and Food Science, Budapest University of Technology and Economics, 1111 Budapest, Hungary;
| | - Yejin Kim
- Institute of Translational Medicine, Semmelweis University, 1094 Budapest, Hungary; (Y.K.); (K.-s.C.)
| | - Kyu-sung Choi
- Institute of Translational Medicine, Semmelweis University, 1094 Budapest, Hungary; (Y.K.); (K.-s.C.)
| | - Csilla E. Németh
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, 1094 Budapest, Hungary; (B.L.); (C.E.N.); (G.B.)
| | - Paola Marcolongo
- Department of Molecular and Developmental Medicine, University of Siena, 53100 Siena, Italy; (P.M.); (A.B.)
| | - Angelo Benedetti
- Department of Molecular and Developmental Medicine, University of Siena, 53100 Siena, Italy; (P.M.); (A.B.)
| | - Gábor Bánhegyi
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, 1094 Budapest, Hungary; (B.L.); (C.E.N.); (G.B.)
| | - Éva Margittai
- Institute of Translational Medicine, Semmelweis University, 1094 Budapest, Hungary; (Y.K.); (K.-s.C.)
- Correspondence: ; Tel.: +36-459-1500 (ext. 60311); Fax: +36-1-2662615
| |
Collapse
|
3
|
Sperb-Ludwig F, Pinheiro FC, Bettio Soares M, Nalin T, Ribeiro EM, Steiner CE, Ribeiro Valadares E, Porta G, Fishinger Moura de Souza C, Schwartz IVD. Glycogen storage diseases: Twenty-seven new variants in a cohort of 125 patients. Mol Genet Genomic Med 2019; 7:e877. [PMID: 31508908 PMCID: PMC6825860 DOI: 10.1002/mgg3.877] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 05/07/2019] [Accepted: 07/08/2019] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Hepatic glycogen storage diseases (GSDs) are a group of rare genetic disorders in which glycogen cannot be metabolized to glucose in the liver because of enzyme deficiencies along the glycogenolytic pathway. GSDs are well-recognized diseases that can occur without the full spectrum, and with overlapping in symptoms. METHODS We analyzed a cohort of 125 patients with suspected hepatic GSD through a next-generation sequencing (NGS) gene panel in Ion Torrent platform. New variants were analyzed by pathogenicity prediction tools. RESULTS Twenty-seven new variants predicted as pathogenic were found between 63 variants identified. The most frequent GSD was type Ia (n = 53), followed by Ib (n = 23). The most frequent variants were p.Arg83Cys (39 alleles) and p.Gln347* (14 alleles) in G6PC gene, and p.Leu348Valfs (21 alleles) in SLC37A4 gene. CONCLUSIONS The study presents the largest cohort ever analyzed in Brazilian patients with hepatic glycogenosis. We determined the clinical utility of NGS for diagnosis. The molecular diagnosis of hepatic GSDs enables the characterization of diseases with similar clinical symptoms, avoiding hepatic biopsy and having faster results.
Collapse
Affiliation(s)
- Fernanda Sperb-Ludwig
- Post‐Graduation Program in Genetics and Molecular BiologyUniversidade Federal do Rio Grande do SulPorto AlegreBrazil
- Laboratory of Basic Research and Advanced Investigations in Neurosciences (BRAIN)Hospital de Clínicas de Porto AlegrePorto AlegreBrazil
| | - Franciele Cabral Pinheiro
- Post‐Graduation Program in Genetics and Molecular BiologyUniversidade Federal do Rio Grande do SulPorto AlegreBrazil
- Laboratory of Basic Research and Advanced Investigations in Neurosciences (BRAIN)Hospital de Clínicas de Porto AlegrePorto AlegreBrazil
| | - Malu Bettio Soares
- Laboratory of Basic Research and Advanced Investigations in Neurosciences (BRAIN)Hospital de Clínicas de Porto AlegrePorto AlegreBrazil
| | - Tatiele Nalin
- Post‐Graduation Program in Genetics and Molecular BiologyUniversidade Federal do Rio Grande do SulPorto AlegreBrazil
| | | | | | - Eugênia Ribeiro Valadares
- Departamento de Propedêutica ComplementarFaculdade de Medicina da Universidade Federal de Minas GeraisBelo HorizonteBrazil
| | - Gilda Porta
- Hospital Infantil Menino JesusSão PauloBrazil
| | | | - Ida Vanessa Doederlein Schwartz
- Post‐Graduation Program in Genetics and Molecular BiologyUniversidade Federal do Rio Grande do SulPorto AlegreBrazil
- Laboratory of Basic Research and Advanced Investigations in Neurosciences (BRAIN)Hospital de Clínicas de Porto AlegrePorto AlegreBrazil
- Medical Genetics ServiceHospital de Clínicas de Porto AlegrePorto AlegreBrazil
| |
Collapse
|
4
|
Direct protein-lipid interactions shape the conformational landscape of secondary transporters. Nat Commun 2018; 9:4151. [PMID: 30297844 PMCID: PMC6175955 DOI: 10.1038/s41467-018-06704-1] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 09/19/2018] [Indexed: 12/31/2022] Open
Abstract
Secondary transporters undergo structural rearrangements to catalyze substrate translocation across the cell membrane – yet how such conformational changes happen within a lipid environment remains poorly understood. Here, we combine hydrogen-deuterium exchange mass spectrometry (HDX-MS) with molecular dynamics (MD) simulations to understand how lipids regulate the conformational dynamics of secondary transporters at the molecular level. Using the homologous transporters XylE, LacY and GlpT from Escherichia coli as model systems, we discover that conserved networks of charged residues act as molecular switches that drive the conformational transition between different states. We reveal that these molecular switches are regulated by interactions with surrounding phospholipids and show that phosphatidylethanolamine interferes with the formation of the conserved networks and favors an inward-facing state. Overall, this work provides insights into the importance of lipids in shaping the conformational landscape of an important class of transporters. Secondary transporters catalyse substrate translocation across the cell membrane but the role of lipids during the transport cycle remains unclear. Here authors used hydrogen-deuterium exchange mass spectrometry and molecular dynamics simulations to understand how lipids regulate the conformational dynamics of secondary transporters.
Collapse
|
5
|
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: 23] [Impact Index Per Article: 3.8] [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.
Collapse
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
| |
Collapse
|
6
|
Letkemann R, Wittkowski H, Antonopoulos A, Podskabi T, Haslam SM, Föll D, Dell A, Marquardt T. Partial correction of neutrophil dysfunction by oral galactose therapy in glycogen storage disease type Ib. Int Immunopharmacol 2017; 44:216-225. [PMID: 28126686 DOI: 10.1016/j.intimp.2017.01.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 01/06/2017] [Accepted: 01/10/2017] [Indexed: 01/30/2023]
Abstract
Glycogen storage disease type Ib (GSD-Ib) is characterized by impaired glucose homeostasis, neutropenia and neutrophil dysfunction. Mass spectrometric glycomic profiling of GSD-Ib neutrophils showed severely truncated N-glycans, lacking galactose. Experiments indicated the hypoglycosylation of the electron transporting subunit of NADPH oxidase, which is crucial for the defense against bacterial infections. In phosphoglucomutase 1 (PGM1) deficiency, an inherited disorder with an enzymatic defect just one metabolic step ahead, hypogalactosylation can be successfully treated by dietary galactose. We hypothesized the same pathomechanism in GSD-Ib and started a therapeutic trial with oral galactose and uridine. The aim was to improve neutrophil dysfunction through the correction of hypoglycosylation in neutrophils. The GSD-Ib patient was treated for 29weeks. Monitoring included glycomics analysis of the patient's neutrophils and neutrophil function tests including respiratory burst activity, phagocytosis and migration. Although no substantial restoration of neutrophil glycosylation was found, there was partial improvement of respiratory burst activity.
Collapse
Affiliation(s)
- Rudolf Letkemann
- Department of General Pediatrics, Metabolic Diseases, University Children's Hospital Muenster, Germany.
| | - Helmut Wittkowski
- Department of Pediatric Rheumatology and Imunology, University Children's Hospital Muenster, Germany.
| | | | - Teodor Podskabi
- Molecular Genetics and Metabolism Laboratory, Munich, Germany.
| | - Stuart M Haslam
- Department of Life Sciences, Imperial College London, SW7 2AZ, UK.
| | - Dirk Föll
- Department of Pediatric Rheumatology and Imunology, University Children's Hospital Muenster, Germany.
| | - Anne Dell
- Department of Life Sciences, Imperial College London, SW7 2AZ, UK.
| | - Thorsten Marquardt
- Department of General Pediatrics, Metabolic Diseases, University Children's Hospital Muenster, Germany.
| |
Collapse
|
7
|
Melis D, Pivonello R, Cozzolino M, Della Casa R, Balivo F, Del Puente A, Dionisi-Vici C, Cotugno G, Zuppaldi C, Rigoldi M, Parini R, Colao A, Andria G, Parenti G. Impaired bone metabolism in glycogen storage disease type 1 is associated with poor metabolic control in type 1a and with granulocyte colony-stimulating factor therapy in type 1b. Horm Res Paediatr 2015; 81:55-62. [PMID: 24401800 DOI: 10.1159/000351022] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2012] [Accepted: 03/27/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Glycogen storage disease type 1 (GSD1) is a rare and genetically heterogeneous metabolic defect of gluconeogenesis due to mutations of either the G6PC gene (GSD1a) or the SLC37A4 gene (GSD1b). Osteopenia is a known complication of GSD1. OBJECTIVES The aim of this study was to investigate the effects of poor metabolic control and/or use of GSD1-specific treatments on bone mineral density (BMD) and metabolism in GSD1 patients. METHODS In a multicenter, cross-sectional case-control study, we studied 38 GSD1 (29 GSD1a and 9 GSD1b) patients. Clinical, biochemical and instrumental parameters indicative of bone metabolism were analyzed; BMD was evaluated by dual-emission X-ray absorptiometry and quantitative ultrasound. RESULTS Both GSD1a and GSD1b patients showed reduced BMD compared with age-matched controls. In GSD1a patients, these abnormalities correlated with compliance to diet and biochemical indicators of metabolic control. In GSD1b patients, BMD correlated with the age at first administration and the duration of granulocyte colony-stimulating factor (G-CSF) therapy. CONCLUSIONS Our data indicate that good metabolic control and compliance with diet are highly recommended to improve bone metabolism in GSD1a patients. GSD1b patients on G-CSF treatment should be carefully monitored for the risk of osteopenia/osteoporosis.
Collapse
Affiliation(s)
- D Melis
- Dipartimenti di Pediatria, Università Federico II, Napoli, Italy
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
8
|
Melis D, Della Casa R, Balivo F, Minopoli G, Rossi A, Salerno M, Andria G, Parenti G. Involvement of endocrine system in a patient affected by glycogen storage disease 1b: speculation on the role of autoimmunity. Ital J Pediatr 2014; 40:30. [PMID: 24646511 PMCID: PMC3974180 DOI: 10.1186/1824-7288-40-30] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Accepted: 02/27/2014] [Indexed: 11/14/2022] Open
Abstract
Glycogen storage disease type 1b (GSD1b) is an inherited metabolic defect of glycogenolysis and gluconeogenesis due to mutations of the SLC37A4 gene and to defective transport of glucose-6-phosphate. The clinical presentation of GSD1b is characterized by hepatomegaly, failure to thrive, fasting hypoglycemia, and dyslipidemia. Patients affected by GSD1b also show neutropenia and/or neutrophil dysfunction that cause increased susceptibility to recurrent bacterial infections. GSD1b patients are also at risk for inflammatory bowel disease. Occasional reports suggesting an increased risk of autoimmune disorders in GSD1b patients, have been published. These complications affect the clinical outcome of the patients. Here we describe the occurrence of autoimmune endocrine disorders including thyroiditis and growth hormone deficiency, in a patient affected by GSD1b. This case further supports the association between GSD1b and autoimmune diseases.
Collapse
Affiliation(s)
- Daniela Melis
- Department of Translational Medical Sciences, Section of Pediatrics, Federico II University, Via S, Pansini 5, 80131 Naples, Italy.
| | | | | | | | | | | | | | | |
Collapse
|
9
|
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.
Collapse
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
| |
Collapse
|
10
|
|
11
|
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.
Collapse
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.
| | | | | |
Collapse
|
12
|
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.
Collapse
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.
| | | | | |
Collapse
|
13
|
Melis D, Pivonello R, Parenti G, Della Casa R, Salerno M, Balivo F, Piccolo P, Di Somma C, Colao A, Andria G. The growth hormone-insulin-like growth factor axis in glycogen storage disease type 1: evidence of different growth patterns and insulin-like growth factor levels in patients with glycogen storage disease type 1a and 1b. J Pediatr 2010; 156:663-70.e1. [PMID: 20022338 DOI: 10.1016/j.jpeds.2009.10.032] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2009] [Revised: 09/28/2009] [Accepted: 10/16/2009] [Indexed: 11/29/2022]
Abstract
OBJECTIVES To investigate the growth hormone (GH)-insulin-like growth factor (IGF) system in patients with glycogen storage disease type 1 (GSD1). STUDY DESIGN This was a prospective, case-control study. Ten patients with GSD1a and 7 patients with GSD1b who were given dietary treatment and 34 sex-, age-, body mass index-, and pubertal stage-matched control subjects entered the study. Auxological parameters were correlated with circulating GH, either at basal or after growth hormone releasing hormone plus arginine test, insulin-like growth factors (IGF-I and IGF-II), and anti-pituitary antibodies (APA). RESULTS Short stature was detected in 10.0% of patients with GSD1a, 42.9% of patients with GSD1b (P = .02), and none of the control subjects. Serum IGF-I levels were lower in patients with GSD1b (P = .0001). An impaired GH secretion was found in 40% of patients with GSD1a (P = .008), 57.1% of patients with GSD1b (P = .006), and none of the control subjects. Short stature was demonstrated in 3 of 4 patients with GSD1b and GH deficiency. The prevalence of APA was significantly higher in patients with GSD1b than in patients with GSD1a (P = .02) and control subjects (P = .03). The GH response to the provocative test inversely correlated with the presence of APA (P = .003). Compared with levels in control subjects, serum IGF-II and insulin levels were higher in both groups of patients, in whom IGF-II levels directly correlated with height SD scores (P = .003). CONCLUSION Patients with GSD1a have an impaired GH secretion associated with reference range serum IGF-I levels and normal stature, whereas in patients with GSD1b, the impaired GH secretion, probably because of the presence of APA, was associated with reduced IGF-I levels and increased prevalence of short stature. The increased IGF-II levels, probably caused by increased insulin levels, in patients with GSD1 are presumably responsible for the improved growth pattern observed in patients receiving strict dietary treatment.
Collapse
Affiliation(s)
- Daniela Melis
- Department of Pediatrics, Federico II University, Naples, Italy
| | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Melis D, Della Casa R, Parini R, Rigoldi M, Cacciapuoti C, Marcolongo P, Benedetti A, Gaudieri V, Andria G, Parenti G. Vitamin E supplementation improves neutropenia and reduces the frequency of infections in patients with glycogen storage disease type 1b. Eur J Pediatr 2009; 168:1069-74. [PMID: 19066956 DOI: 10.1007/s00431-008-0889-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2008] [Accepted: 11/19/2008] [Indexed: 01/07/2023]
Abstract
BACKGROUND Neutropenia and/or neutrophil dysfunction are part of glycogen storage disease type 1b (GSD1b) phenotype. Recent studies indicated that activation of apoptosis and increased reactive oxygen species are implicated in the pathogenesis of neutropenia in GSD1b. METHODS We studied seven GSD1b patients over a 2-year-period to evaluate the efficacy of vitamin E, a known antioxidant, in preventing or improving the clinical manifestations associated with neutropenia and neutrophil dysfunction. Frequency and severity of infections, neutrophil counts and function, ileocolonoscopy and intestinal histology, were monitored. During the first year, patients did not assume vitamin E; during the second year of the study, vitamin E supplementation was added to their therapeutic regimens. RESULTS During vitamin E supplementation, the mean values of neutrophil counts were significantly higher (p < 0.05) and neutrophil counts lower than 500/mm(3) were found less frequently (p < 0.05); the frequency and severity of infections, mouth ulcers and perianal lesions, was reduced (p < 0.05); ileocolonoscopy and histology showed a mild improvement. Vitamin E supplementation did not result in changes in neutrophil function. CONCLUSIONS These results suggest that vitamin E supplementation might be beneficial in GSD1b patients and may alleviate disease manifestations associated with neutropenia.
Collapse
Affiliation(s)
- D Melis
- Department of Pediatrics, Federico II University, Via Sergio Pansini, 5, Naples 80131, Italy
| | | | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Chen SY, Pan CJ, Lee S, Peng W, Chou JY. Functional analysis of mutations in the glucose-6-phosphate transporter that cause glycogen storage disease type Ib. Mol Genet Metab 2008; 95:220-3. [PMID: 18835800 PMCID: PMC3422630 DOI: 10.1016/j.ymgme.2008.08.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2008] [Revised: 08/24/2008] [Accepted: 08/25/2008] [Indexed: 10/21/2022]
Abstract
The glucose-6-phosphate transporter (G6PT) deficient in glycogen storage disease type Ib is a phosphate (P(i))-linked antiporter capable of G6P: P(i) and P(i):P(i) exchanges. We previously characterized G6PT mutations by measuring G6P uptake activities in microsomes co-expressing G6PT and glucose-6-phosphatase-alpha. Here we report a new assay, based on reconstituted proteoliposomes carrying only G6PT, and characterize G6P and P(i) uptake activities of 23 G6PT mutations. We show that co-expression and G6PT-only assays are equivalent in measuring G6PT activity. However, the p.Q133P mutation exhibits differential G6P and P(i) transport activities, suggesting that characterizing G6P and P(i) transport activities of G6PT mutations may yield insights to this genetic disorder.
Collapse
Affiliation(s)
- Shih-Yin Chen
- Section on Cellular Differentiation, Program on Developmental Endocrinology and Genetics, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
| | - Chi-Jiunn Pan
- Section on Cellular Differentiation, Program on Developmental Endocrinology and Genetics, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
| | - Soojung Lee
- Section on Cellular Differentiation, Program on Developmental Endocrinology and Genetics, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
| | - Wentao Peng
- Section on Cellular Differentiation, Program on Developmental Endocrinology and Genetics, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
| | - Janice Y. Chou
- Section on Cellular Differentiation, Program on Developmental Endocrinology and Genetics, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
| |
Collapse
|
16
|
Chou JY, Mansfield BC. Mutations in the glucose-6-phosphatase-alpha (G6PC) gene that cause type Ia glycogen storage disease. Hum Mutat 2008; 29:921-30. [PMID: 18449899 DOI: 10.1002/humu.20772] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Glucose-6-phosphatase-alpha (G6PC) is a key enzyme in glucose homeostasis that catalyzes the hydrolysis of glucose-6-phosphate to glucose and phosphate in the terminal step of gluconeogenesis and glycogenolysis. Mutations in the G6PC gene, located on chromosome 17q21, result in glycogen storage disease type Ia (GSD-Ia), an autosomal recessive metabolic disorder. GSD-Ia patients manifest a disturbed glucose homeostasis, characterized by fasting hypoglycemia, hepatomegaly, nephromegaly, hyperlipidemia, hyperuricemia, lactic acidemia, and growth retardation. G6PC is a highly hydrophobic glycoprotein, anchored in the membrane of the endoplasmic reticulum with the active center facing into the lumen. To date, 54 missense, 10 nonsense, 17 insertion/deletion, and three splicing mutations in the G6PC gene have been identified in more than 550 patients. Of these, 50 missense, two nonsense, and two insertion/deletion mutations have been functionally characterized for their effects on enzymatic activity and stability. While GSD-Ia is not more prevalent in any ethnic group, mutations unique to Caucasian, Oriental, and Jewish populations have been described. Despite this, GSD-Ia patients exhibit phenotypic heterogeneity and a stringent genotype-phenotype relationship does not exist.
Collapse
Affiliation(s)
- Janice Y Chou
- Section on Cellular Differentiation, Heritable Disorders Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-1830, USA.
| | | |
Collapse
|
17
|
Chen SY, Pan CJ, Nandigama K, Mansfield BC, Ambudkar SV, Chou JY. The glucose-6-phosphate transporter is a phosphate-linked antiporter deficient in glycogen storage disease type Ib and Ic. FASEB J 2008; 22:2206-13. [PMID: 18337460 DOI: 10.1096/fj.07-104851] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Glycogen storage disease type Ib (GSD-Ib) is caused by deficiencies in the glucose-6-phosphate (G6P) transporter (G6PT) that have been well characterized. Interestingly, deleterious mutations in the G6PT gene were identified in clinical cases of GSD type Ic (GSD-Ic) proposed to be deficient in an inorganic phosphate (P(i)) transporter. We hypothesized that G6PT is both the G6P and P(i) transporter. Using reconstituted proteoliposomes we show that both G6P and P(i) are efficiently taken up into P(i)-loaded G6PT-proteoliposomes. The G6P uptake activity decreases as the internal:external P(i) ratio decreases and the P(i) uptake activity decreases in the presence of external G6P. Moreover, G6P or P(i) uptake activity is not detectable in P(i)-loaded proteoliposomes containing the p.R28H G6PT null mutant. The G6PT-proteoliposome-mediated G6P or P(i) uptake is inhibited by cholorgenic acid and vanadate, both specific G6PT inhibitors. Glucose-6-phosphatase-alpha (G6Pase-alpha), which facilitates microsomal G6P uptake by G6PT, fails to stimulate G6P uptake in P(i)-loaded G6PT-proteoliposomes, suggesting that the G6Pase-alpha-mediated stimulation is caused by decreasing G6P and increasing P(i) concentrations in microsomes. Taken together, our results suggest that G6PT has a dual role as a G6P and a P(i) transporter and that GSD-Ib and GSD-Ic are deficient in the same G6PT gene.
Collapse
Affiliation(s)
- Shih-Yin Chen
- Section on Cellular Differentiation, Heritable Disorders Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-1830, USA
| | | | | | | | | | | |
Collapse
|
18
|
Abstract
Glycogen storage diseases (GSD) are inherited metabolic disorders of glycogen metabolism. Different hormones, including insulin, glucagon, and cortisol regulate the relationship of glycolysis, gluconeogenesis and glycogen synthesis. The overall GSD incidence is estimated 1 case per 20000-43000 live births. There are over 12 types and they are classified based on the enzyme deficiency and the affected tissue. Disorders of glycogen degradation may affect primarily the liver, the muscle, or both. Type Ia involves the liver, kidney and intestine (and Ib also leukocytes), and the clinical manifestations are hepatomegaly, failure to thrive, hypoglycemia, hyperlactatemia, hyperuricemia and hyperlipidemia. Type IIIa involves both the liver and muscle, and IIIb solely the liver. The liver symptoms generally improve with age. Type IV usually presents in the first year of life, with hepatomegaly and growth retardation. The disease in general is progressive to cirrhosis. Type VI and IX are a heterogeneous group of diseases caused by a deficiency of the liver phosphorylase and phosphorylase kinase system. There is no hyperuricemia or hyperlactatemia. Type XI is characterized by hepatic glycogenosis and renal Fanconi syndrome. Type II is a prototype of inborn lysosomal storage diseases and involves many organs but primarily the muscle. Types V and VII involve only the muscle.
Collapse
Affiliation(s)
- Hasan Ozen
- Division of Gastroenterology, Hepatology and Nutrition, Hacettepe University Children's Hospital, Ankara, Turkey.
| |
Collapse
|
19
|
Melis D, Pivonello R, Parenti G, Della Casa R, Salerno M, Lombardi G, Sebastio G, Colao A, Andria G. Increased prevalence of thyroid autoimmunity and hypothyroidism in patients with glycogen storage disease type I. J Pediatr 2007; 150:300-5, 305.e1. [PMID: 17307551 DOI: 10.1016/j.jpeds.2006.11.056] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2005] [Revised: 07/27/2006] [Accepted: 11/22/2006] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To investigate the hypothalamus-pituitary-thyroid axis in patients with glycogen storage disease type 1(GSD1). STUDY DESIGN Ten patients with GSD1a, 7 patients with GSD1b, and 34 sex- and age-matched healthy control subjects were enrolled in the study. RESULTS The levels of serum-free thyroxine (FT4) were significantly lower in patients with GSD1a and GSD1b (P < .05), whereas thyrotropin was significantly higher compared with control subjects only in patients with GSD1b (P < .005). Thyroglobulin and thyroperoxidase auto-antibodies were significantly higher in patients with GSD1b than in patients with GSD1a and control subjects (P < .005). After thyrotropin-releasing hormone stimulation, an enhanced thyrotropin response was found in patients with GSD1a and patients with GSD1b (P < .005) compared with control subjects. The presence of a subclinical or overt hypothyroidism was found in 4 of 7 patients with GSD1b and in no patient with GSD1a (chi2 = 7.47, P < .005) or control subject (chi2 = 27.2, P < .0001). CONCLUSIONS Patients with GSD1b have an increased prevalence of thyroid autoimmunity and hypothyroidism, although patients with GSD1a have little evidence of thyroid abnormalities. Concomitant damage at the level of the hypothalamus or pituitary gland might be hypothesized on the basis of the slightly elevated thyrotropin levels, even in patients with overt hypothyroidism.
Collapse
Affiliation(s)
- Daniela Melis
- Department of Pediatrics, Federico II University, Naples, Italy
| | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Lam CW, Yan MSC, Law TY, Tong SF, Orrico A, Galli L, Sorrentino V, Benedetti A. Resequencing the G6PT1 gene reveals a novel splicing mutation in a patient with glycogen storage disease type 1b. Clin Chim Acta 2006; 374:147-8. [PMID: 16716283 DOI: 10.1016/j.cca.2006.04.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2006] [Revised: 03/13/2006] [Accepted: 04/03/2006] [Indexed: 10/24/2022]
|
21
|
Lizák B, Czegle I, Csala M, Benedetti A, Mandl J, Bánhegyi G. Translocon pores in the endoplasmic reticulum are permeable to small anions. Am J Physiol Cell Physiol 2006; 291:C511-7. [PMID: 16611737 DOI: 10.1152/ajpcell.00274.2005] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Contribution of translocon peptide channels to the permeation of low molecular mass anions was investigated in rat liver microsomes. Puromycin, which purges translocon pores of nascent polypeptides, creating additional empty pores, raised the microsomal uptake of radiolabeled UDP-glucuronic acid, while it did not increase the uptake of glucose-6-phosphate or glutathione. The role of translocon pores in the transport of small anions was also investigated by measuring the effect of puromycin on the activity of microsomal enzymes with intraluminal active sites. The mannose-6-phosphatase activity of glucose-6-phosphatase and the activity of UDP-glucuronosyltransferase were elevated upon addition of puromycin, but glucose-6-phosphatase and beta-glucuronidase activities were not changed. The increase in enzyme activities was due to a better access of the substrates to the luminal compartment rather than to activation of the enzymes. Antibody against Sec61 translocon component decreased the activity of UDP-glucuronosyltransferase and antagonized the effect of puromycin. Similarly, the addition of the puromycin antagonist anisomycin or treatments of microsomes, resulting in the release of attached ribosomes, prevented the puromycin-dependent increase in the activity. Mannose-6-phosphatase and UDP-glucuronosyltransferase activities of smooth microsomal vesicles showed higher basal latencies that were not affected by puromycin. In conclusion, translationally inactive, ribosome-bound translocons allow small anions to cross the endoplasmic reticulum membrane. This pathway can contribute to the nonspecific substrate supply of enzymes with intraluminal active centers.
Collapse
Affiliation(s)
- Beáta Lizák
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, PO Box 260, 1444 Budapest, Hungary
| | | | | | | | | | | |
Collapse
|
22
|
Senesi S, Marcolongo P, Kardon T, Bucci G, Sukhodub A, Burchell A, Benedetti A, Fulceri R. Immunodetection of the expression of microsomal proteins encoded by the glucose 6-phosphate transporter gene. Biochem J 2005; 389:57-62. [PMID: 15757503 PMCID: PMC1184538 DOI: 10.1042/bj20050213] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Glucose 6-phosphate transport has been well characterized in liver microsomes. The transport is required for the functioning of the glucose-6-phosphatase enzyme that is situated in the lumen of the hepatic endoplasmic reticulum. The genetic deficiency of the glucose 6-phosphate transport activity causes a severe metabolic disease termed type 1b glycogen storage disease. The cDNA encoding a liver transporter for glucose 6-phosphate was cloned and was found to be mutated in patients suffering from glycogen storage disease 1b. While related mRNAs have been described in liver and other tissues, the encoded protein(s) has not been immunologically characterized yet. In the present study, we report (using antibodies against three different peptides of the predicted amino acid sequence) that a major protein encoded by the glucose 6-phosphate transporter gene is expressed in the endoplasmic reticulum membranes of rat and human liver. The protein has an apparent molecular mass of approx. 33 kDa using SDS/PAGE, but several lines of evidence indicate that its real molecular mass is 46 kDa, as expected. The glucose 6-phosphate transporter protein was also immunodetected in kidney microsomes, but not in microsomes derived from human fibrocytes, rat spleen and lung, and a variety of cell lines. Moreover, little or no expression of the glucose 6-phosphate transporter protein was found in liver microsomes obtained from three glycogen storage disease 1b patients, even bearing mutations that do not directly interfere with protein translation, which can be explained by a (proteasome-mediated) degradation of the mutated transporter.
Collapse
Affiliation(s)
- Silvia Senesi
- *Dipartimento di Fisiopatologia, Medicina Sperimentale e Sanità Pubblica, University of Siena, Via A. Moro 3, 53100-Siena, Italy
| | - Paola Marcolongo
- *Dipartimento di Fisiopatologia, Medicina Sperimentale e Sanità Pubblica, University of Siena, Via A. Moro 3, 53100-Siena, Italy
| | - Tamas Kardon
- †Department of Medical Chemistry, Semmelweis University, 1444-Budapest, Hungary
| | - Giovanna Bucci
- *Dipartimento di Fisiopatologia, Medicina Sperimentale e Sanità Pubblica, University of Siena, Via A. Moro 3, 53100-Siena, Italy
| | - Andrey Sukhodub
- ‡Division of Maternal and Child Health Sciences, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, U.K
| | - Ann Burchell
- ‡Division of Maternal and Child Health Sciences, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, U.K
| | - Angelo Benedetti
- *Dipartimento di Fisiopatologia, Medicina Sperimentale e Sanità Pubblica, University of Siena, Via A. Moro 3, 53100-Siena, Italy
- To whom correspondence should be addressed (email )
| | - Rosella Fulceri
- *Dipartimento di Fisiopatologia, Medicina Sperimentale e Sanità Pubblica, University of Siena, Via A. Moro 3, 53100-Siena, Italy
| |
Collapse
|
23
|
Melis D, Fulceri R, Parenti G, Marcolongo P, Gatti R, Parini R, Riva E, Della Casa R, Zammarchi E, Andria G, Benedetti A. Genotype/phenotype correlation in glycogen storage disease type 1b: a multicentre study and review of the literature. Eur J Pediatr 2005; 164:501-8. [PMID: 15906092 DOI: 10.1007/s00431-005-1657-4] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2004] [Accepted: 02/15/2005] [Indexed: 01/15/2023]
Abstract
UNLABELLED We studied the genotype/phenotype correlation in a cohort of glycogen storage disease type (GSD) 1b patients. A total of 25 GSD1b patients, 13 females and 12 males, age range: 4.3-28.4 years, mean:14.6+/-6.8 years; median: 15 years, representing the entire case load of Italian GSD1b patients, were enrolled in the study. Molecular analysis of the glucose 6-phosphate translocase (G6PT1) gene was performed in all patients. We analysed the presence of a correlation among both the clinical features associated with GSD1b (neutropenia, frequency of admission to the hospital for severe infections) and the presence of systemic complications (liver adenomas, nephropathy, bone mineral density defect, polycystic ovaries, short stature, inflammatory bowel disease) and the mutations detected in each patient. Nine patients were homozygous or compound heterozygous for mutations causing stop codons. In particular, three patients were homozygous for the same mutation (400X); of these patients, one showed chronic neutropenia with severe and frequent infections and severe inflammatory bowel disease, another patient cyclic neutropenia associated with rare bacterial infections and mild bowel involvement and the last one normal neutrophil count. Two patients were homozygous for the mutation 128X; one of these patients did not show neutropenia, whereas the other one had severe neutropenia needing frequent hospital admission and was under granulocyte-colony stimulating factor treatment. In three patients no mutations were detected. CONCLUSION No correlation was found between individual mutations and the presence of neutropenia, bacterial infections and systemic complications. These results suggest that different genes and proteins modulate neutrophil differentiation, maturation and apoptosis and thus the severity and frequency of infections. The absence of detectable mutations in three patients could suggest that a second protein plays a role in microsomal phosphate transport.
Collapse
Affiliation(s)
- Daniela Melis
- Dipartimento di Pediatria, Università Federico II, Via Sergio Pansini 5, 80131 Napoli, Italy.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
24
|
Melis D, Parenti G, Gatti R, Casa RD, Parini R, Riva E, Burlina AB, Dionisi Vici C, Di Rocco M, Furlan F, Torcoletti M, Papadia F, Donati A, Benigno V, Andria G. Efficacy of ACE-inhibitor therapy on renal disease in glycogen storage disease type 1: a multicentre retrospective study. Clin Endocrinol (Oxf) 2005; 63:19-25. [PMID: 15963056 DOI: 10.1111/j.1365-2265.2005.02292.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
BACKGROUND The efficacy of ACE-inhibitors in decreasing microalbuminuria and proteinuria has been reported in a few patients with glycogen storage disease type 1 (GSD1); however, no case-control study has ever been published. AIM The aim of the current study was to evaluate the efficacy of ACE-inhibitors in reducing glomerular hyperfiltration, microalbuminuria and proteinuria, and in delaying the progression of renal damage. PATIENTS AND METHODS Ninety-five patients (median age at the time of the study: 14.5 years) were enrolled from nine Italian referral centres for metabolic diseases. A retrospective study of a 10-year follow-up was conducted in order to compare the evolution of these parameters in treated patients with those who were not treated with ACE-inhibitors. RESULTS A significant and progressive decrease of glomerular filtration rate was observed in treated patients vs. those who were not treated with ACE-inhibitors (P < 0.05). No difference was observed for microalbuminuria and proteinuria between the two groups of patients. Moreover, the ACE-inhibitors significantly delayed the progression from glomerular hyperfiltration to microalbuminuria, but not that from microalbuminuria to proteinuria. CONCLUSIONS The results of the present study underline the importance of a strict follow-up of renal function in GSD1 patients. The detection of glomerular hyperfiltration suggests precocious initiation of ACE-inhibitor treatment to delay the progression of renal damage. A randomized prospective study is needed to establish for certain the real effectiveness of this treatment in GSD1 patients.
Collapse
Affiliation(s)
- D Melis
- Dipartimento di Pediatria, Università Federico II, Napoli, Italy.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Han SH, Ki CS, Lee JE, Hong YJ, Son BK, Lee KH, Choe YH, Lee SY, Kim JW. A novel mutation (A148V) in the glucose 6-phosphate translocase (SLC37A4) gene in a Korean patient with glycogen storage disease type 1b. J Korean Med Sci 2005; 20:499-501. [PMID: 15953877 PMCID: PMC2782211 DOI: 10.3346/jkms.2005.20.3.499] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
We report a Korean patient with glycogen storage disease type 1b (GSD-1b) whose diagnosis was confirmed by liver biopsy and laboratory results. The patient presented with delay of puberty and short stature on admission and had typical clinical symptoms of GSD as well as chronic neutropenia and inflammatory bowel disease. Mutation analysis of the glucose 6-phosphate translocase 6-phosphate translocase (SLC37A4) gene revealed that the patient was a compound heterozygote of two different mutations including a deletion mutation (c.1042_1043delCT; L348fs) and a missense mutation (A148V). The L348fs mutation was inherited from the patient's father and has been reported in an Italian family with GSD-1b, while the A148V mutation was transmitted from the patient's mother and was a novel mutation. To the best of our knowledge, this is the first report of genetically confirmed case of GSD-1b in Korean.
Collapse
Affiliation(s)
- Sung-Hee Han
- Department of Laboratory Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Chang-Seok Ki
- Department of Laboratory Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Ji-Eun Lee
- Department of Pediatrics, College of Medicine, Inha University, Inchon, Korea
| | - Young-Jin Hong
- Department of Pediatrics, College of Medicine, Inha University, Inchon, Korea
| | - Byong-Kwan Son
- Department of Pediatrics, College of Medicine, Inha University, Inchon, Korea
| | - Kyung-Hee Lee
- Department of Radiology, College of Medicine, Inha University, Inchon, Korea
| | - Yon-Ho Choe
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Soo-Youn Lee
- Department of Laboratory Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Jong-Won Kim
- Department of Laboratory Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| |
Collapse
|
26
|
Miltenberger-Miltenyi G, Szonyi L, Balogh L, Utermann G, Janecke AR. Mutation spectrum of type I glycogen storage disease in Hungary. J Inherit Metab Dis 2005; 28:939-44. [PMID: 16435186 DOI: 10.1007/s10545-005-0186-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2005] [Accepted: 09/27/2005] [Indexed: 11/27/2022]
Abstract
We performed mutation analysis in 12 Hungarian type I glycogen storage disease (GSD I) patients in order to determine the mutation spectrum. All patients were clinically classified as GSD Ia. Nine patients carried biallelic G6PC mutations (p.Q27fsX35, p.D38V, p.W70X, p.K76N, p.W77R, p.R83C, p.E110Q, p.G222R), with E110Q reported only in Hungary. However, three patients displayed two common G6PT1 (SLC37A4) mutations (p.L348fsX400, p.C183R) which were originally described in association with GSD Inon-a. Review of the literature and our data show that G6PT1 mutations are not associated with neutropenia and related clinical findings in approximately 10% of these cases. Homozygosity for the truncating G6PT1 mutation p.L348fsX400 can be observed with and without neutropenia, indicating that one or more modifiers of the action of G6PT1 exist. Our data are suitable to provide DNA-based and thus noninvasive confirmation of diagnosis in Hungarian patients with this disorder.
Collapse
Affiliation(s)
- G Miltenberger-Miltenyi
- Department of Medical Genetics, Molecular and Clinical Pharmacology, Innsbruck Medical University, Innsbruck, Austria.
| | | | | | | | | |
Collapse
|
27
|
Melis D, Havelaar AC, Verbeek E, Smit GPA, Benedetti A, Mancini GMS, Verheijen F. NPT4, a new microsomal phosphate transporter: mutation analysis in glycogen storage disease type Ic. J Inherit Metab Dis 2004; 27:725-33. [PMID: 15505377 DOI: 10.1023/b:boli.0000045755.89308.2f] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Deficiency of a microsomal phosphate transporter in the liver has been suggested in some patients affected by glycogen storage disease type Ic (GSD Ic). Several Na(+)/phosphate co-transporters have been characterized as members of the anion-cation symporter family. Recently, the cDNA sequence of two phosphate transporters, NPT3 and NPT4, expressed in liver, kidney and intestine, has been determined. We studied expression of human NPT4 in COS cells and observed an ER localization of the transporter by immunofluorescence microscopy. We speculated that this transporter could play a role in the regulation of the glucose-6-phosphatase (G6-Pase) complex. We revealed the genomic structure of NPT4 and analysed the gene as a candidate for GSD Ic. DNA was collected from five patients without mutations in G6-Pase or the G6-P transporter gene. DNA analysis of NPT4 revealed that one patient was heterozygous for a G>A transition at nucleotide 601 which would result in a G201R substitution. Our results do not confirm the hypothesis that this gene is mutated in GSD Ic patients. However, we cannot exclude that the mutation found reduces the phosphate transport efficiency, possibly modulating the G6-Pase complex.
Collapse
Affiliation(s)
- D Melis
- Department of Clinical Genetics, Erasmus University Rotterdam, The Netherlands.
| | | | | | | | | | | | | |
Collapse
|
28
|
Leuzzi R, Bánhegyi G, Kardon T, Marcolongo P, Capecchi PL, Burger HJ, Benedetti A, Fulceri R. Inhibition of microsomal glucose-6-phosphate transport in human neutrophils results in apoptosis: a potential explanation for neutrophil dysfunction in glycogen storage disease type 1b. Blood 2003; 101:2381-7. [PMID: 12424192 DOI: 10.1182/blood-2002-08-2576] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Mutations in the gene of the hepatic glucose-6-phosphate transporter cause glycogen storage disease type 1b. In this disease, the altered glucose homeostasis and liver functions are accompanied by an impairment of neutrophils/monocytes. However, neither the existence of a microsomal glucose-6-phosphate transport, nor the connection between its defect and cell dysfunction has been demonstrated in neutrophils/monocytes. In this study we have characterized the microsomal glucose-6-phosphate transport of human neutrophils and differentiated HL-60 cells. The transport of glucose-6-phosphate was sensitive to the chlorogenic acid derivative S3483, N-ethylmaleimide, and 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, known inhibitors of the hepatic microsomal glucose-6-phosphate transporter. A glucose-6-phosphate uptake was also present in microsomes from undifferentiated HL-60 and Jurkat cells, but it was insensitive to S3483. The treatment with S3484 of intact human neutrophils and differentiated HL-60 cells mimicked some leukocyte defects of glycogen storage disease type 1b patients (ie, the drug inhibited phorbol myristate acetate-induced superoxide anion production and reduced the size of endoplasmic reticulum Ca(2+) stores). Importantly, the treatment with S3484 also resulted in apoptosis of human neutrophils and differentiated HL-60 cells, while undifferentiated HL-60 and Jurkat cells were unaffected by the drug. The proapoptotic effect of S3483 was prevented by the inhibition of nicotinamide adenine dinucleotide phosphate oxidase or by antioxidant treatment. These results suggest that microsomal glucose-6-phosphate transport has a role in the antioxidant protection of neutrophils, and that the genetic defect of the transporter leads to the impairment of cellular functions and apoptosis.
Collapse
Affiliation(s)
- Rosanna Leuzzi
- Dipartimento di Fisiopatologia e Medicina Sperimentale and Istituto di Semeiotica Medica, Università di Siena, Siena, Italy
| | | | | | | | | | | | | | | |
Collapse
|
29
|
Clottes E, Middleditch C, Burchell A. Rat liver glucose-6-phosphatase system: light scattering and chemical characterization. Arch Biochem Biophys 2002; 408:33-41. [PMID: 12485600 DOI: 10.1016/s0003-9861(02)00523-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Glucose-6-phosphatase is a multicomponent system located in the endoplasmic reticulum, involving both a catalytic subunit (G6PC) and several substrate and product carriers. The glucose-6-phosphate carrier is called G6PT1. Using light scattering, we determined K(D) values for phosphate and glucose transport in rat liver microsomes (45 and 33mM, respectively), G6PT1 K(D) being too low to be estimated by this technique. We provide evidence that phosphate transport may be carried out by an allosteric multisubunit translocase or by two distinct proteins. Using chemical modifications by sulfhydryl reagents with different solubility properties, we conclude that in G6PT1, one thiol group important for activity is facing the cytosol and could be Cys(121) or Cys(362). Moreover, a different glucose-6-phosphate translocase, representing 20% of total glucose-6-phosphate transport and insensitive to N-ethylmaleimide modification, could coexist with liver G6PT1. In the G6PC protein, an accessible thiol group is facing the cytosol and, according to structural predictions, could be Cys(284).
Collapse
Affiliation(s)
- Eric Clottes
- Laboratoire Inter-universitaire des Activités Physiques et Sportives, Faculté de Médecine, 28 Place Henri Dunant, 63001, Clermont-Ferrand Cedex, France
| | | | | |
Collapse
|
30
|
Yuen YP, Cheng WF, Tong SF, Chan YT, Chan YW, Lam CW. Novel missense mutation (Y24H) in the G6PT1 gene causing glycogen storage disease type 1b. Mol Genet Metab 2002; 77:249-51. [PMID: 12409273 DOI: 10.1016/s1096-7192(02)00110-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We describe a Chinese patient with glycogen storage disease type 1b presenting with failure to thrive and protuberant abdomen. The neutropenia was mild and the patient did not have fasting hypoglycemia. Direct DNA sequencing of the G6PT1 gene revealed the patient to be a compound heterozygote of a novel missense mutation, Y24H, and another missense mutation, P191L, which we had described previously. The mother is heterozygous for the Y24H mutation and the father is heterozygous for the P191L mutation. Y24H and P191L may be ethnic-specific mutations as they have not been reported in other populations. The DNA-based diagnosis of GSD 1b will enable us to make an accurate determination of carrier status and to perform prenatal diagnosis of this disease.
Collapse
Affiliation(s)
- Yuet-Ping Yuen
- Department of Pathology, Princess Margaret Hospital, Hong Kong, China
| | | | | | | | | | | |
Collapse
|
31
|
Benedetti A, Fulceri R, Allan BB, Houston P, Sukhodub AL, Marcolongo P, Ethell B, Burchell B, Burchell A. Histone 2A stimulates glucose-6-phosphatase activity by permeabilization of liver microsomes. Biochem J 2002; 367:505-10. [PMID: 12097138 PMCID: PMC1222888 DOI: 10.1042/bj20020187] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2002] [Revised: 06/07/2002] [Accepted: 07/03/2002] [Indexed: 01/06/2023]
Abstract
Histone 2A increases glucose-6-phosphatase activity in liver microsomes. The effect has been attributed either to the conformational change of the enzyme, or to the permeabilization of microsomal membrane that allows the free access of substrate to the intraluminal glucose-6-phosphatase catalytic site. The aim of the present study was the critical reinvestigation of the mechanism of action of histone 2A. It has been found that the dose-effect curve of histone 2A is different from that of detergents and resembles that of the pore-forming alamethicin. Inhibitory effects of EGTA on glucose-6-phosphatase activity previously reported in histone 2A-treated microsomes have been also found in alamethicin-permeabilized vesicles. The effect of EGTA cannot therefore simply be an antagonization of the effect of histone 2A. Histone 2A stimulates the activity of another latent microsomal enzyme, UDP-glucuronosyltransferase, which has an intraluminal catalytic site. Finally, histone 2A renders microsomal vesicles permeable to non-permeant compounds. Taken together, the results demonstrate that histone 2A stimulates glucose-6-phosphatase activity by permeabilizing the microsomal membrane.
Collapse
Affiliation(s)
- Angelo Benedetti
- Dipartimento di Fisiopatologia e Medicina Sperimentale, University of Siena, 53100 Siena, Italy
| | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Abstract
Glucose-6-phosphatase (G6Pase), an enzyme found mainly in the liver and the kidneys, plays the important role of providing glucose during starvation. Unlike most phosphatases acting on water-soluble compounds, it is a membrane-bound enzyme, being associated with the endoplasmic reticulum. In 1975, W. Arion and co-workers proposed a model according to which G6Pase was thought to be a rather unspecific phosphatase, with its catalytic site oriented towards the lumen of the endoplasmic reticulum [Arion, Wallin, Lange and Ballas (1975) Mol. Cell. Biochem. 6, 75--83]. Substrate would be provided to this enzyme by a translocase that is specific for glucose 6-phosphate, thereby accounting for the specificity of the phosphatase for glucose 6-phosphate in intact microsomes. Distinct transporters would allow inorganic phosphate and glucose to leave the vesicles. At variance with this substrate-transport model, other models propose that conformational changes play an important role in the properties of G6Pase. The last 10 years have witnessed important progress in our knowledge of the glucose 6-phosphate hydrolysis system. The genes encoding G6Pase and the glucose 6-phosphate translocase have been cloned and shown to be mutated in glycogen storage disease type Ia and type Ib respectively. The gene encoding a G6Pase-related protein, expressed specifically in pancreatic islets, has also been cloned. Specific potent inhibitors of G6Pase and of the glucose 6-phosphate translocase have been synthesized or isolated from micro-organisms. These as well as other findings support the model initially proposed by Arion. Much progress has also been made with regard to the regulation of the expression of G6Pase by insulin, glucocorticoids, cAMP and glucose.
Collapse
Affiliation(s)
- Emile van Schaftingen
- Laboratoire de Chimie Physiologique, UCL and ICP, Avenue Hippocrate 75, B-1200 Brussels, Belgium.
| | | |
Collapse
|
33
|
Leuzzi R, Fulceri R, Marcolongo P, Bánhegyi G, Zammarchi E, Stafford K, Burchell A, Benedetti A. Glucose 6-phosphate transport in fibroblast microsomes from glycogen storage disease type 1b patients: evidence for multiple glucose 6-phosphate transport systems. Biochem J 2001; 357:557-62. [PMID: 11439108 PMCID: PMC1221985 DOI: 10.1042/0264-6021:3570557] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In liver endoplasmic reticulum the intralumenal glucose-6-phosphatase activity requires the operation of a glucose 6-phosphate transporter (G6PT1). Mutations in the gene encoding G6PT1 cause glycogen storage disease type 1b, which is characterized by a loss of glucose-6-phosphatase activity and impaired glucose homoeostasis. We describe a novel glucose 6-phosphate (G6P) transport activity in microsomes from human fibroblasts and HeLa cells. This transport activity is unrelated to G6PT1 since: (i) it was similar in microsomes of skin fibroblasts from glycogen storage disease type 1b patients homozygous for mutations of the G6PT1 gene, and in microsomes from human control subjects; (ii) it was insensitive to the G6PT1 inhibitor chlorogenic acid; and (iii) it was equally active towards G6P and glucose 1-phosphate, whereas G6PT1 is highly selective for G6P. Taken together, our results provide evidence for the presence of multiple transporters for G6P (and other hexose phosphoesters) in the endoplasmic reticulum.
Collapse
Affiliation(s)
- R Leuzzi
- Dipartimento di Fisiopatologia e Medicina Sperimentale, Università di Siena, Viale A. Moro no. 1, 53100-Siena, Italy
| | | | | | | | | | | | | | | |
Collapse
|
34
|
Abstract
Glycogen storage disease type 1 (GSD 1) comprises a group of autosomal recessive inherited metabolic disorders caused by deficiency of the microsomal multicomponent glucose-6-phosphatase system. Of the two known transmembrane proteins of the system, malfunction of the catalytic subunit (G6Pase) characterizes GSD 1a. GSD 1 non-a is characterized by defective microsomal glucose-6-phosphate or pyrophosphate/phosphate transport due to mutations in G6PT (glucose-6-phosphate translocase gene) encoding a microsomal transporter protein. Mutations in G6Pase and G6PT account for approximately 80 and approximately 20% of GSD 1 cases, respectively. G6Pase and G6PT work in concert to maintain glucose homeostasis in gluconeogenic organs. Whereas G6Pase is exclusively expressed in gluconeogenic cells, G6PT is ubiquitously expressed and its deficiency generally causes a more severe phenotype. Rapid confirmation of clinically suspected diagnosis of GSD 1, reliable carrier testing, and prenatal diagnosis are facilitated by mutation analyses of the chromosome 11-bound G6PT gene as well as the chromosome 17-bound G6Pase gene.
Collapse
Affiliation(s)
- A R Janecke
- Institute of Medical Biology and Human Genetics, University of Innsbruck, Austria.
| | | | | |
Collapse
|
35
|
Chen LY, Lin B, Pan CJ, Hiraiwa H, Chou JY. Structural requirements for the stability and microsomal transport activity of the human glucose 6-phosphate transporter. J Biol Chem 2000; 275:34280-6. [PMID: 10940311 DOI: 10.1074/jbc.m006439200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Deficiencies in glucose 6-phosphate (G6P) transporter (G6PT), a 10-helical endoplasmic reticulum transmembrane protein of 429 amino acids, cause glycogen storage disease type 1b. To date, only three missense mutations in G6PT have been shown to abolish microsomal G6P transport activity. Here, we report the results of structure-function studies on human G6PT and demonstrate that 15 missense mutations and a codon deletion (delta F93) mutation abolish microsomal G6P uptake activity and that two splicing mutations cause exon skipping. While most missense mutants support the synthesis of G6PT protein similar to that of the wild-type transporter, immunoblot analysis shows that G20D, delta F93, and I278N mutations, located in helix 1, 2, and 6, respectively, destabilize the G6PT. Further, we demonstrate that G6PT mutants lacking an intact helix 10 are misfolded and undergo degradation within cells. Moreover, amino acids 415-417 in the cytoplasmic tail of the carboxyl-domain, extending from helix 10, also play a critical role in the correct folding of the transporter. However, the last 12 amino acids of the cytoplasmic tail play no essential role(s) in functional integrity of the G6PT. Our results, for the first time, elucidate the structural requirements for the stability and transport activity of the G6PT protein.
Collapse
Affiliation(s)
- L Y Chen
- Heritable Disorders Branch, NICHD, National Institutes of Health, Bethesda, Maryland 20892, USA
| | | | | | | | | |
Collapse
|
36
|
Méchin MC, van de Werve G. Glucose-6-phosphate transporter and receptor functions of the glucose 6-phosphatase system analyzed from a consensus defined by multiple alignments. Proteins 2000; 41:164-72. [PMID: 10966570 DOI: 10.1002/1097-0134(20001101)41:2<164::aid-prot20>3.0.co;2-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The cDNA encoding the protein (P46) that is mutated in glycogen storage disease type-1b (GSD-1b) has been previously cloned by homology with bacterial sequences of the uhp (upper hexose phosphate) system. Hydropathic profiles, transmembrane-prediction analysis, and a multiple alignment of 14 sequences related to P46 (with percentage of identity around 30%) allowed to identify two large domains in the proteins linked by a large variable loop. Highly conserved transmembrane (TM) segments, TM1 and TM4 in the first domain and TM5 in the second one, were identified almost in all the integral proteins related to P46. The multiple alignment allowed definition of a consensus involving the 14 sequences related to P46. The detailed comparison of the consensus with the UhpT (the bacterial G6P transporter) and with UhpC (the bacterial G6P receptor) sequences reveals that the P46 protein could carry both G6P receptor and transporter functions.
Collapse
Affiliation(s)
- M C Méchin
- Laboratoire d'Endocrinologie Métabolique, Departments of Nutrition and Biochemistry, Groupe de Recherche en Transport Membranaire, Centre de Recherche du CHUM, Université de Montréal, Montréal, Québec, Canada.
| | | |
Collapse
|
37
|
Lam CW, Sin SY, Lau ET, Lam YY, Poon P, Tong SF. Prenatal diagnosis of glycogen storage disease type 1b using denaturing high performance liquid chromatography. Prenat Diagn 2000; 20:765-8. [PMID: 11015710 DOI: 10.1002/1097-0223(200009)20:9<765::aid-pd893>3.0.co;2-s] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Glycogen storage disease type 1b (GSD1b) is an autosomal recessive inborn error of metabolism caused by deficiency of glucose-6-phosphate translocase (G6PT1). Current laboratory diagnosis for GSD1b is established by a functional enzyme assay of glucose-6-phosphatase in both fresh and detergent-treated liver homogenates. This procedure requires liver biopsy and is impractical for routine prenatal diagnosis owing to the high morbidity of fetal liver biopsy. Recently, the gene for GSD1b has been cloned and the prevalent mutations in different ethnic groups have been determined. In this study, prenatal molecular diagnosis was performed for a Chinese family in which a previous child was born homozygous for the G149E mutation. We detected genomic sequence variants by heteroduplex formation, followed by denaturing high performance liquid chromatography (DHPLC). With this method, post-PCR analysis was shortened to 7 min. In the case we analysed, PCR products amplified from the fetal DNA yielded a single peak in the chromatogram, indicating a homozygous state in the fetus. When wild-type PCR products were mixed with fetal PCR products, two peaks were observed, indicating that the fetus was homozygous for the parental (G149E) mutation. Sequencing results confirmed this diagnosis. As a result, the pregnancy was terminated and the diagnosis was confirmed on DNA analysis of the aborted fetus. We show here that DNA mutation analysis can be used in the prenatal diagnosis of GSD1b and that DHPLC promises to be a robust technique for this and other prenatal molecular diagnoses.
Collapse
Affiliation(s)
- C W Lam
- Department of Chemical Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, China.
| | | | | | | | | | | |
Collapse
|
38
|
Streeper RS, Svitek CA, Goldman JK, O'Brien RM. Differential role of hepatocyte nuclear factor-1 in the regulation of glucose-6-phosphatase catalytic subunit gene transcription by cAMP in liver- and kidney-derived cell lines. J Biol Chem 2000; 275:12108-18. [PMID: 10766845 DOI: 10.1074/jbc.275.16.12108] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In liver and kidney, the terminal step in gluconeogenesis is catalyzed by glucose-6-phosphatase. To examine the effect of the cAMP signal transduction pathway on transcription of the gene encoding the catalytic subunit of glucose-6-phosphatase (G6Pase), G6Pase-chloramphenicol acetyltransferase (CAT) fusion genes were transiently transfected into either the liver-derived HepG2 or kidney-derived LLC-PK cell line. Co-transfection of an expression vector encoding the catalytic subunit of cAMP-dependent protein kinase (PKA) markedly stimulated G6Pase-CAT fusion gene expression, and mutational analysis of the G6Pase promoter revealed that multiple regions are required for this PKA response in both the HepG2 and LLC-PK cell lines. A sequence in the G6Pase promoter that resembles a cAMP response element is required for the full PKA response in both HepG2 and LLC-PK cells. However, in LLC-PK cells, but not in HepG2 cells, a hepatocyte nuclear factor-1 (HNF-1) binding site was critical for the full induction of G6Pase-CAT expression by PKA. Changing this HNF-1 motif to that for the yeast transcription factor GAL4 reduces the PKA response in LLC-PK cells to the same degree as deleting the HNF-1 site. However, co-transfection of this mutated construct with chimeric proteins comprising the GAL4-DNA binding domain ligated to the coding sequence for HNF-1alpha, HNF-1beta, HNF-3, or HNF-4 completely restored the PKA response. Thus, we hypothesize that, in LLC-PK cells, HNF-1 is acting as an accessory factor to enhance PKA signaling through the cAMP response element by altering G6Pase promoter conformation or accessibility rather than specifically affecting some component of the PKA signal transduction pathway.
Collapse
Affiliation(s)
- R S Streeper
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, Tennessee 37232, USA
| | | | | | | |
Collapse
|