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Song A, Mao Y, Wei H. GLUT5: structure, functions, diseases and potential applications. Acta Biochim Biophys Sin (Shanghai) 2023; 55:1519-1538. [PMID: 37674366 PMCID: PMC10582729 DOI: 10.3724/abbs.2023158] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Accepted: 05/19/2023] [Indexed: 09/08/2023] Open
Abstract
Glucose transporter 5 (GLUT5) is a membrane transporter that specifically transports fructose and plays a key role in dietary fructose uptake and metabolism. In recent years, a high fructose diet has occupied an important position in the daily intake of human beings, resulting in a significant increase in the incidence of obesity and metabolic diseases worldwide. Over the past few decades, GLUT5 has been well understood to play a significant role in the pathogenesis of human digestive diseases. Recently, the role of GLUT5 in human cancer has received widespread attention, and a large number of studies have focused on exploring the effects of changes in GLUT5 expression levels on cancer cell survival, metabolism and metastasis. However, due to various difficulties and shortcomings, the molecular structure and mechanism of GLUT5 have not been fully elucidated, which to some extent prevents us from revealing the relationship between GLUT5 expression and cell carcinogenesis at the protein molecular level. In this review, we summarize the current understanding of the structure and function of mammalian GLUT5 and its relationship to intestinal diseases and cancer and suggest that GLUT5 may be an important target for cancer therapy.
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Affiliation(s)
- Aqian Song
- Department of GastroenterologyBeijing Ditan HospitalCapital Medical UniversityBeijing100015China
| | - Yuanpeng Mao
- Department of GastroenterologyPeking University Ditan Teaching HospitalBeijing100015China
| | - Hongshan Wei
- Department of GastroenterologyBeijing Ditan HospitalCapital Medical UniversityBeijing100015China
- Department of GastroenterologyPeking University Ditan Teaching HospitalBeijing100015China
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2
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Abstract
The consumption of fructose as sugar and high-fructose corn syrup has markedly increased during the past several decades. This trend coincides with the exponential rise of metabolic diseases, including obesity, nonalcoholic fatty liver disease, cardiovascular disease, and diabetes. While the biochemical pathways of fructose metabolism were elucidated in the early 1990s, organismal-level fructose metabolism and its whole-body pathophysiological impacts have been only recently investigated. In this review, we discuss the history of fructose consumption, biochemical and molecular pathways involved in fructose metabolism in different organs and gut microbiota, the role of fructose in the pathogenesis of metabolic diseases, and the remaining questions to treat such diseases.
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Affiliation(s)
- Sunhee Jung
- Department of Biological Chemistry, University of California, Irvine, California, USA
| | - Hosung Bae
- Department of Biological Chemistry, University of California, Irvine, California, USA
| | - Won-Suk Song
- Department of Biological Chemistry, University of California, Irvine, California, USA;,Institute of Bioengineering, Bio-MAX, Seoul National University, Seoul, South Korea
| | - Cholsoon Jang
- Department of Biological Chemistry, University of California, Irvine, California, USA;,Chao Family Comprehensive Cancer Center, University of California, Irvine, California, USA,Center for Complex Biological Systems, University of California, Irvine, California, USA,Center for Epigenetics and Metabolism, University of California, Irvine, California, USA
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3
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Peng C, Jian X, Xie Y, Li L, Ouyang J, Tang L, Zhang X, Su J, Zhao S, Liu H, Yin M, Wu D, Wan M, Xie L, Chen X. Genomic alterations of dermatofibrosarcoma protuberans revealed by whole-genome sequencing. Br J Dermatol 2022; 186:997-1009. [PMID: 35441365 PMCID: PMC9325047 DOI: 10.1111/bjd.20976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 12/18/2021] [Accepted: 12/30/2021] [Indexed: 11/29/2022]
Abstract
Background Dermatofibrosarcoma protuberans (DFSP) is a rare and marginal cutaneous sarcoma of intermediate‐grade malignancy, for which the genomic landscape remains unclear. Understanding the landscape of DFSP will help to further classify the genomic pathway of malignant development in soft tissue. Objectives To identify the comprehensive molecular pathogenesis of DFSP. Methods In this study, the comprehensive genomic features, with 53 tumour‐normal pairs of DFSP, were revealed by whole‐genome sequencing. Results The mutational signature 1 (C > T mutation at CpG dinucleotides) is featured in DFSP, resulting in higher mutations in DNA replication. Interestingly, the recurrence of DFSP is correlated with low tumour mutation burden. Novel mutation genes in DFSP were identified, including MUC4/6, KMT2C and BRCA1, and subsequently, three molecular subtypes of DFSP were classified on the basis of MUC4 and MUC6 mutations. Various structural aberrations including genomic rearrangements were identified in DSFPs, particularly in 17q and 22q, which cause oncogene amplification (AKT1, SPHK1, COL1A1, PDGFβ) or tumour suppressor deletion (CDKN2A/B). In addition to gene fusion of COL1A1‐PDGFβ [t(17;22)], we identified gene fusion of SLC2A5‐BTBD7 [t(1;14)] in DFSP through whole‐genome sequencing, and verified it experimentally. Enrichment analysis of altered molecules revealed that DNA repair, cell cycle, phosphoinositide 3‐kinase and Janus kinase pathways were primarily involved in DFSP. Conclusions This is the first large‐scale whole‐genome sequencing for DFSP, and our findings describe the comprehensive genomic landscape, highlighting the molecular complexity and genomic aberrations of DFSP. Our findings also provide novel potential diagnostic and therapeutic targets for this disease. What is already known about this topic?Chromosomal translocation between chromosome 17 and chromosome 22 is the main feature in the pathogenesis of dermatofibrosarcoma protuberans (DFSP).
What does this study add?We describe the comprehensive genomic landscape of DFSP, highlighting the molecular complexity and genomic aberrations. Our findings provide novel potential diagnostic and therapeutic targets for this disease.
What is the translational message?Our study revealed novel molecular subtypes of DFSP based on genetic mutations, which benefits precision diagnosis. We also found oncogene amplification, including AKT1 and SPHK1, which provides novel potential target molecules for further DFSP treatment. In addition to gene fusion of COL1A1‐PDGFβ, we identified a novel gene fusion of SLC2A5‐BTBD7 in DFSP, which is a novel potential diagnostic and therapeutic target for this disease.
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Affiliation(s)
- Cong Peng
- Department of Dermatology, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Hunan Key Laboratory of Skin Cancer and Psoriasis, Changsha, Hunan, China.,Hunan Engineering Research Center of Skin Health and Disease, Changsha, Hunan, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, Hunan, China
| | - Xingxing Jian
- Department of Dermatology, Xiangya Hospital, Central South University, Changsha, Hunan, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, Hunan, China.,Shanghai-MOST Key Laboratory of Health and Disease Genomics, Institute for Genome and Bioinformatics, Shanghai Institute for Biomedical and Pharmaceutical Technologies, Shanghai, China
| | - Yang Xie
- Department of Dermatology, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Lingfeng Li
- Department of Dermatology, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Hunan Key Laboratory of Skin Cancer and Psoriasis, Changsha, Hunan, China.,Hunan Engineering Research Center of Skin Health and Disease, Changsha, Hunan, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, Hunan, China
| | - Jian Ouyang
- Shanghai-MOST Key Laboratory of Health and Disease Genomics, Institute for Genome and Bioinformatics, Shanghai Institute for Biomedical and Pharmaceutical Technologies, Shanghai, China
| | - Ling Tang
- Department of Dermatology, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Hunan Key Laboratory of Skin Cancer and Psoriasis, Changsha, Hunan, China.,Hunan Engineering Research Center of Skin Health and Disease, Changsha, Hunan, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, Hunan, China
| | - Xu Zhang
- Department of Dermatology, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Hunan Key Laboratory of Skin Cancer and Psoriasis, Changsha, Hunan, China.,Hunan Engineering Research Center of Skin Health and Disease, Changsha, Hunan, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, Hunan, China
| | - Juan Su
- Department of Dermatology, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Hunan Key Laboratory of Skin Cancer and Psoriasis, Changsha, Hunan, China.,Hunan Engineering Research Center of Skin Health and Disease, Changsha, Hunan, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, Hunan, China
| | - Shuang Zhao
- Department of Dermatology, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Hunan Key Laboratory of Skin Cancer and Psoriasis, Changsha, Hunan, China.,Hunan Engineering Research Center of Skin Health and Disease, Changsha, Hunan, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, Hunan, China
| | - Hong Liu
- Department of Dermatology, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Hunan Key Laboratory of Skin Cancer and Psoriasis, Changsha, Hunan, China.,Hunan Engineering Research Center of Skin Health and Disease, Changsha, Hunan, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, Hunan, China
| | - Mingzhu Yin
- Department of Dermatology, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Hunan Key Laboratory of Skin Cancer and Psoriasis, Changsha, Hunan, China.,Hunan Engineering Research Center of Skin Health and Disease, Changsha, Hunan, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, Hunan, China
| | - Dan Wu
- Shanghai-MOST Key Laboratory of Health and Disease Genomics, Institute for Genome and Bioinformatics, Shanghai Institute for Biomedical and Pharmaceutical Technologies, Shanghai, China
| | - Miaojian Wan
- Department of Dermatology, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Lu Xie
- Shanghai-MOST Key Laboratory of Health and Disease Genomics, Institute for Genome and Bioinformatics, Shanghai Institute for Biomedical and Pharmaceutical Technologies, Shanghai, China
| | - Xiang Chen
- Department of Dermatology, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Hunan Key Laboratory of Skin Cancer and Psoriasis, Changsha, Hunan, China.,Hunan Engineering Research Center of Skin Health and Disease, Changsha, Hunan, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, Hunan, China
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4
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Broekaert IJ, Borrelli O, Dolinsek J, Martin-de-Carpi J, Mas E, Miele E, Pienar C, Ribes-Koninckx C, Thomassen R, Thomson M, Tzivinikos C, Benninga M. An ESPGHAN Position Paper on the Use of Breath Testing in Paediatric Gastroenterology. J Pediatr Gastroenterol Nutr 2022; 74:123-137. [PMID: 34292218 DOI: 10.1097/mpg.0000000000003245] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
OBJECTIVES Given a lack of a systematic approach to the use of breath testing in paediatric patients, the aim of this position paper is to provide expert guidance regarding the indications for its use and practical considerations to optimise its utility and safety. METHODS Nine clinical questions regarding methodology, interpretation, and specific indications of breath testing and treatment of carbohydrate malabsorption were addressed by members of the Gastroenterology Committee (GIC) of the European Society for Paediatric Gastroenterology Hepatology and Nutrition (ESPGHAN).A systematic literature search was performed from 1983 to 2020 using PubMed, the MEDLINE and Cochrane Database of Systematic Reviews. Grading of Recommendations, Assessment, Development, and Evaluation was applied to evaluate the outcomes.During a consensus meeting, all recommendations were discussed and finalised. In the absence of evidence from randomised controlled trials, recommendations reflect the expert opinion of the authors. RESULTS A total of 22 recommendations were voted on using the nominal voting technique. At first, recommendations on prerequisites and preparation for as well as on interpretation of breath tests are given. Then, recommendations on the usefulness of H2-lactose breath testing, H2-fructose breath testing as well as of breath tests for other types of carbohydrate malabsorption are provided. Furthermore, breath testing is recommended to diagnose small intestinal bacterial overgrowth (SIBO), to control for success of Helicobacter pylori eradication therapy and to diagnose and monitor therapy of exocrine pancreatic insufficiency, but not to estimate oro-caecal transit time (OCTT) or to diagnose and follow-up on celiac disease. CONCLUSIONS Breath tests are frequently used in paediatric gastroenterology mainly assessing carbohydrate malabsorption, but also in the diagnosis of small intestinal overgrowth, fat malabsorption, H. pylori infection as well as for measuring gastrointestinal transit times. Interpretation of the results can be challenging and in addition, pertinent symptoms should be considered to evaluate clinical tolerance.
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Affiliation(s)
- Ilse Julia Broekaert
- Department of Paediatrics, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Osvaldo Borrelli
- Department of Paediatric Gastroenterology, Great Ormond Street Hospital, London, UK
| | - Jernej Dolinsek
- Department of Paediatrics, University Medical Centre Maribor, Maribor, Slovenia
| | - Javier Martin-de-Carpi
- Department of Paediatric Gastroenterology, Hepatology and Nutrition, Hospital Sant Joan de Déu, Barcelona, Spain
| | - Emmanuel Mas
- Unité de Gastroentérologie, Hépatologie, Nutrition, Diabétologie et Maladies Héréditaires du Métabolisme, Hôpital des Enfants, CHU de Toulouse, Toulouse, France; IRSD, Université de Toulouse, INSERM, INRA, ENVT, UPS, Toulouse, France
| | - Erasmo Miele
- Department of Translational Medical Science, Section of Paediatrics, University of Naples "Federico", Naples, Italy
| | - Corina Pienar
- Department of Paediatrics, "Victor Babes" University of Medicine and Pharmacy, Timisoara, Romania
| | - Carmen Ribes-Koninckx
- Department of Paediatric Gastroenterology, Hepatology & Nutrition, La Fe University Hospital, Valencia, Spain
| | - Rut Thomassen
- Department of Paediatric Medicine, Division of Paediatric and Adolescent Medicine, Oslo University Hospital, Norway
| | - Mike Thomson
- Centre for Paediatric Gastroenterology, Sheffield Children's Hospital, Sheffield, UK
| | - Christos Tzivinikos
- Department of Paediatric Gastroenterology, Al Jalila Children's Specialty Hospital, Dubai, UAE
| | - Marc Benninga
- Department of Paediatric Gastroenterology and Nutrition, Emma Children's Hospital, Amsterdam University Medical Centres, Amsterdam, The Netherlands
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Szabó J, Maróti G, Solymosi N, Andrásofszky E, Tuboly T, Bersényi A, Bruckner G, Hullár I. Fructose, glucose and fat interrelationships with metabolic pathway regulation and effects on the gut microbiota. Acta Vet Hung 2021; 69:134-156. [PMID: 34224398 DOI: 10.1556/004.2021.00022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 06/04/2021] [Indexed: 12/14/2022]
Abstract
The purpose of this 30-day feeding study was to elucidate the changes, correlations, and mechanisms caused by the replacement of the starch content of the AIN-93G diet (St) with glucose (G), fructose (F) or lard (L) in body and organ weights, metabolic changes and caecal microbiota composition in rats (Wistar, SPF). The body weight gain of rats on the F diet was 12% less (P = 0.12) than in the St group. Rats on the L diet consumed 18.6% less feed, 31% more energy and gained 58.4% more than the animals on the St diet, indicating that, in addition to higher energy intake, better feed utilisation is a key factor in the obesogenic effect of diets of high nutrient and energy density. The G, F and L diets significantly increased the lipid content of the liver (St: 7.01 ± 1.48; G: 14.53 ± 8.77; F: 16.73 ± 8.77; L: 19.86 ± 4.92% of DM), suggesting that lipid accumulation in the liver is not a fructose-specific process. Relative to the St control, specific glucose effects were the decreasing serum glucagon (-41%) concentrations and glucagon/leptin ratio and the increasing serum leptin concentrations (+26%); specific fructose effects were the increased weights of the kidney, spleen, epididymal fat and the decreased weight of retroperitoneal fat and the lower immune response, as well as the increased insulin (+26%), glucagon (+26%) and decreased leptin (-25%) levels. This suggests a mild insulin resistance and catabolic metabolism in F rats. Specific lard effects were the decreased insulin (-9.14%) and increased glucagon (+40.44%) and leptin (+44.92%) levels. Relative to St, all diets increased the operational taxonomic units of the phylum Bacteroidetes. G and L decreased, while F increased the proportion of Firmicutes. F and L diets decreased the proportions of Actinobacteria, Proteobacteria and Verrucomicrobia. Correlation and centrality analyses were conducted to ascertain the positive and negative correlations and relative weights of the 32 parameters studied in the metabolic network. These correlations and the underlying potential mechanisms are discussed.
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Affiliation(s)
- József Szabó
- 1Department of Animal Breeding, Nutrition and Laboratory Animal Science, University of Veterinary Medicine, P. O. Box 2, H-1400 Budapest, Hungary
| | - Gergely Maróti
- 2Biological Research Centre, Institute of Plant Biology, Szeged, Hungary
| | - Norbert Solymosi
- 3Centre for Bioinformatics, University of Veterinary Medicine, Budapest, Hungary
| | - Emese Andrásofszky
- 1Department of Animal Breeding, Nutrition and Laboratory Animal Science, University of Veterinary Medicine, P. O. Box 2, H-1400 Budapest, Hungary
| | - Tamás Tuboly
- 4Department of Microbiology and Infectious Diseases, University of Veterinary Medicine, Budapest, Hungary
| | - András Bersényi
- 1Department of Animal Breeding, Nutrition and Laboratory Animal Science, University of Veterinary Medicine, P. O. Box 2, H-1400 Budapest, Hungary
| | - Geza Bruckner
- 5Department of Athletic Training and Clinical Nutrition, University of Kentucky, Lexington, KY, USA
| | - István Hullár
- 1Department of Animal Breeding, Nutrition and Laboratory Animal Science, University of Veterinary Medicine, P. O. Box 2, H-1400 Budapest, Hungary
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6
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Evangelista-Silva PH, Prates RP, Leite JSM, Moreno LG, Goulart-Silva F, Esteves EA. Intestinal GLUT5 and FAT/CD36 transporters and blood glucose are reduced by a carotenoid/MUFA-rich oil in high-fat fed mice. Life Sci 2021; 279:119672. [PMID: 34097971 DOI: 10.1016/j.lfs.2021.119672] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 05/20/2021] [Accepted: 05/22/2021] [Indexed: 10/21/2022]
Abstract
AIMS Intestinal nutrient absorption plays a vital role in developing obesity, and nutrient transporters expressed in the enterocytes facilitate this process. Moreover, previous studies have shown that specific foods and diets can affect their cell levels. Herein, we investigated the effects of pequi oil (PO), which is high in several bioactive compounds, on intestinal nutrient transporter levels as well as on intestinal morphology and metabolic biomarkers. MAIN METHODS Groups of male C57BL/6 mice were fed either a standard (C) or a high-fat diet (HFD) and pequi oil (CP and HFDP with PO by gavage at 150 mg/day) for eight weeks. Food intake and body weight were monitored, serum metabolic biomarkers, intestinal transporter levels and histological analyses were performed. KEY FINDINGS PO increased caloric intake without increasing body or fat mass regardless of diet. The HFD group treated with PO reduced fasting blood glucose and villus width. PO did not affect GLUT2, L-FABP, FATP4, NPC1L1, NHE3 or PEPT1 content in CP or HFDP groups. GLUT5 and FAT/CD36 levels were reduced in both CP and HFDP. SIGNIFICANCE Our data suggest that PO attenuated monosaccharide and fatty acid absorption, contributing to lower fasting glycemia and higher food intake without affecting body weight or visceral fat of high-fat feed mice.
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Affiliation(s)
- Paulo Henrique Evangelista-Silva
- Faculty of Biological and Health Sciences, Programa de Pós-Graduação Multicêntrico em Ciências Fisiológicas, Universidade Federal dos Vales do Jequitinhonha e Mucuri - UFVJM, Rodovia MGT 367 - Km 583. n. 5000, Alto da Jacuba, Diamantina, MG 39100-000, Brazil; Institute of Biomedical Sciences, Department of Physiology and Biophysics, Universidade de São Paulo - USP, Av. Prof. Dr. Lineu Prestes. 1524, Butantã, São Paulo, SP 05508-000, Brazil
| | - Rodrigo Pereira Prates
- Faculty of Biological and Health Sciences, Programa de Pós-Graduação Multicêntrico em Ciências Fisiológicas, Universidade Federal dos Vales do Jequitinhonha e Mucuri - UFVJM, Rodovia MGT 367 - Km 583. n. 5000, Alto da Jacuba, Diamantina, MG 39100-000, Brazil
| | - Jaqueline Santos Moreira Leite
- Institute of Biomedical Sciences, Department of Physiology and Biophysics, Universidade de São Paulo - USP, Av. Prof. Dr. Lineu Prestes. 1524, Butantã, São Paulo, SP 05508-000, Brazil
| | - Lauane Gomes Moreno
- Faculty of Biological and Health Sciences, Programa de Pós-Graduação Multicêntrico em Ciências Fisiológicas, Universidade Federal dos Vales do Jequitinhonha e Mucuri - UFVJM, Rodovia MGT 367 - Km 583. n. 5000, Alto da Jacuba, Diamantina, MG 39100-000, Brazil
| | - Francemilson Goulart-Silva
- Institute of Biomedical Sciences, Department of Physiology and Biophysics, Universidade de São Paulo - USP, Av. Prof. Dr. Lineu Prestes. 1524, Butantã, São Paulo, SP 05508-000, Brazil
| | - Elizabethe Adriana Esteves
- Faculty of Biological and Health Sciences, Programa de Pós-Graduação Multicêntrico em Ciências Fisiológicas, Universidade Federal dos Vales do Jequitinhonha e Mucuri - UFVJM, Rodovia MGT 367 - Km 583. n. 5000, Alto da Jacuba, Diamantina, MG 39100-000, Brazil.
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Abstract
This review intends to act as an overview of fructose malabsorption (FM) and its role in the aetiology of diseases including, but not limited to, irritable bowel syndrome (IBS) and infantile colic and the relationship between fructose absorption and the propagation of some cancers. IBS results in a variety of symptoms including stomach pains, cramps and bloating. Patients can be categorised into two groups, depending on whether the patients’ experiences either constipation (IBS-C) or diarrhoea (IBS-D). FM has been proposed as a potential cause of IBS-D and other diseases, such as infantile colic. However, our knowledge of FM is limited by our understanding of the biochemistry related to the absorption of fructose in the small intestine and FM’s relationship with small intestinal bacterial overgrowth. It is important to consider the dietary effects on FM and most importantly, the quantity of excess free fructose consumed. The diagnosis of FM is difficult and often requires indirect means that may result in false positives. Current treatments of FM include dietary intervention, such as low fermentable oligo-, di-, monosaccharides and polyols diets and enzymatic treatments, such as the use of xylose isomerase. More research is needed to accurately diagnose and effectively treat FM. This review is designed with the goal of providing a detailed outline of the issues regarding the causes, diagnosis and treatment of FM.
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8
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Koepsell H. Glucose transporters in the small intestine in health and disease. Pflugers Arch 2020; 472:1207-1248. [PMID: 32829466 PMCID: PMC7462918 DOI: 10.1007/s00424-020-02439-5] [Citation(s) in RCA: 124] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 07/11/2020] [Accepted: 07/17/2020] [Indexed: 12/23/2022]
Abstract
Absorption of monosaccharides is mainly mediated by Na+-D-glucose cotransporter SGLT1 and the facititative transporters GLUT2 and GLUT5. SGLT1 and GLUT2 are relevant for absorption of D-glucose and D-galactose while GLUT5 is relevant for D-fructose absorption. SGLT1 and GLUT5 are constantly localized in the brush border membrane (BBM) of enterocytes, whereas GLUT2 is localized in the basolateral membrane (BLM) or the BBM plus BLM at low and high luminal D-glucose concentrations, respectively. At high luminal D-glucose, the abundance SGLT1 in the BBM is increased. Hence, D-glucose absorption at low luminal glucose is mediated via SGLT1 in the BBM and GLUT2 in the BLM whereas high-capacity D-glucose absorption at high luminal glucose is mediated by SGLT1 plus GLUT2 in the BBM and GLUT2 in the BLM. The review describes functions and regulations of SGLT1, GLUT2, and GLUT5 in the small intestine including diurnal variations and carbohydrate-dependent regulations. Also, the roles of SGLT1 and GLUT2 for secretion of enterohormones are discussed. Furthermore, diseases are described that are caused by malfunctions of small intestinal monosaccharide transporters, such as glucose-galactose malabsorption, Fanconi syndrome, and fructose intolerance. Moreover, it is reported how diabetes, small intestinal inflammation, parental nutrition, bariatric surgery, and metformin treatment affect expression of monosaccharide transporters in the small intestine. Finally, food components that decrease D-glucose absorption and drugs in development that inhibit or downregulate SGLT1 in the small intestine are compiled. Models for regulations and combined functions of glucose transporters, and for interplay between D-fructose transport and metabolism, are discussed.
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Affiliation(s)
- Hermann Koepsell
- Institute for Anatomy and Cell Biology, University of Würzburg, Koellikerstr 6, 97070, Würzburg, Germany.
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9
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Holman GD. Structure, function and regulation of mammalian glucose transporters of the SLC2 family. Pflugers Arch 2020; 472:1155-1175. [PMID: 32591905 PMCID: PMC7462842 DOI: 10.1007/s00424-020-02411-3] [Citation(s) in RCA: 95] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 05/27/2020] [Accepted: 05/29/2020] [Indexed: 12/12/2022]
Abstract
The SLC2 genes code for a family of GLUT proteins that are part of the major facilitator superfamily (MFS) of membrane transporters. Crystal structures have recently revealed how the unique protein fold of these proteins enables the catalysis of transport. The proteins have 12 transmembrane spans built from a replicated trimer substructure. This enables 4 trimer substructures to move relative to each other, and thereby alternately opening and closing a cleft to either the internal or the external side of the membrane. The physiological substrate for the GLUTs is usually a hexose but substrates for GLUTs can include urate, dehydro-ascorbate and myo-inositol. The GLUT proteins have varied physiological functions that are related to their principal substrates, the cell type in which the GLUTs are expressed and the extent to which the proteins are associated with subcellular compartments. Some of the GLUT proteins translocate between subcellular compartments and this facilitates the control of their function over long- and short-time scales. The control of GLUT function is necessary for a regulated supply of metabolites (mainly glucose) to tissues. Pathophysiological abnormalities in GLUT proteins are responsible for, or associated with, clinical problems including type 2 diabetes and cancer and a range of tissue disorders, related to tissue-specific GLUT protein profiles. The availability of GLUT crystal structures has facilitated the search for inhibitors and substrates and that are specific for each GLUT and that can be used therapeutically. Recent studies are starting to unravel the drug targetable properties of each of the GLUT proteins.
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Affiliation(s)
- Geoffrey D Holman
- Department of Biology and Biochemistry, University of Bath, Bath, BA2 7AY, UK.
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10
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Gyimesi G, Pujol-Giménez J, Kanai Y, Hediger MA. Sodium-coupled glucose transport, the SLC5 family, and therapeutically relevant inhibitors: from molecular discovery to clinical application. Pflugers Arch 2020; 472:1177-1206. [PMID: 32767111 PMCID: PMC7462921 DOI: 10.1007/s00424-020-02433-x] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 06/24/2020] [Accepted: 07/02/2020] [Indexed: 02/06/2023]
Abstract
Sodium glucose transporters (SGLTs) belong to the mammalian solute carrier family SLC5. This family includes 12 different members in human that mediate the transport of sugars, vitamins, amino acids, or smaller organic ions such as choline. The SLC5 family belongs to the sodium symporter family (SSS), which encompasses transporters from all kingdoms of life. It furthermore shares similarity to the structural fold of the APC (amino acid-polyamine-organocation) transporter family. Three decades after the first molecular identification of the intestinal Na+-glucose cotransporter SGLT1 by expression cloning, many new discoveries have evolved, from mechanistic analysis to molecular genetics, structural biology, drug discovery, and clinical applications. All of these advances have greatly influenced physiology and medicine. While SGLT1 is essential for fast absorption of glucose and galactose in the intestine, the expression of SGLT2 is largely confined to the early part of the kidney proximal tubules, where it reabsorbs the bulk part of filtered glucose. SGLT2 has been successfully exploited by the pharmaceutical industry to develop effective new drugs for the treatment of diabetic patients. These SGLT2 inhibitors, termed gliflozins, also exhibit favorable nephroprotective effects and likely also cardioprotective effects. In addition, given the recent finding that SGLT2 is also expressed in tumors of pancreas and prostate and in glioblastoma, this opens the door to potential new therapeutic strategies for cancer treatment by specifically targeting SGLT2. Likewise, further discoveries related to the functional association of other SGLTs of the SLC5 family to human pathologies will open the door to potential new therapeutic strategies. We furthermore hope that the herein summarized information about the physiological roles of SGLTs and the therapeutic benefits of the gliflozins will be useful for our readers to better understand the molecular basis of the beneficial effects of these inhibitors, also in the context of the tubuloglomerular feedback (TGF), and the renin-angiotensin system (RAS). The detailed mechanisms underlying the clinical benefits of SGLT2 inhibition by gliflozins still warrant further investigation that may serve as a basis for future drug development.
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Affiliation(s)
- Gergely Gyimesi
- Membrane Transport Discovery Lab, Department of Nephrology and Hypertension, and Department of Biomedical Research, Inselspital, University of Bern, Kinderklinik, Office D845, Freiburgstrasse 15, CH-3010, Bern, Switzerland
| | - Jonai Pujol-Giménez
- Membrane Transport Discovery Lab, Department of Nephrology and Hypertension, and Department of Biomedical Research, Inselspital, University of Bern, Kinderklinik, Office D845, Freiburgstrasse 15, CH-3010, Bern, Switzerland
| | - Yoshikatsu Kanai
- Department of Bio-system Pharmacology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Matthias A Hediger
- Membrane Transport Discovery Lab, Department of Nephrology and Hypertension, and Department of Biomedical Research, Inselspital, University of Bern, Kinderklinik, Office D845, Freiburgstrasse 15, CH-3010, Bern, Switzerland.
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11
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Loureiro G, Martel F. The effect of dietary polyphenols on intestinal absorption of glucose and fructose: Relation with obesity and type 2 diabetes. FOOD REVIEWS INTERNATIONAL 2019. [DOI: 10.1080/87559129.2019.1573432] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Guilherme Loureiro
- Department of Biomedicine, Unit of Biochemistry, Faculty of Medicine, University of Porto, Porto, Portugal
| | - Fátima Martel
- Department of Biomedicine, Unit of Biochemistry, Faculty of Medicine, University of Porto, Porto, Portugal
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
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12
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Wiffin M, Smith L, Antonio J, Johnstone J, Beasley L, Roberts J. Effect of a short-term low fermentable oligiosaccharide, disaccharide, monosaccharide and polyol (FODMAP) diet on exercise-related gastrointestinal symptoms. J Int Soc Sports Nutr 2019; 16:1. [PMID: 30646926 PMCID: PMC6332635 DOI: 10.1186/s12970-019-0268-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 01/03/2019] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Research has demonstrated that low fermentable oligiosaccharide, disaccharide, monosaccharide and polyol (FODMAP) diets improve gastrointestinal (GI) symptoms in irritable bowel syndrome sufferers. Exercise-related GI issues are a common cause of underperformance, with current evidence focusing on the use of FODMAP approaches with recreationally competitive or highly trained athletes. However, there is a paucity of research exploring the potential benefit of FODMAP strategies to support healthy, recreational athletes who experience GI issues during training. This study therefore aimed to assess whether a short-term LOWFODMAP diet improved exercise-related GI symptoms and the perceived ability to exercise in recreational runners. METHODS Sixteen healthy volunteers were randomly assigned in a crossover design manner to either a LOWFODMAP (16.06 ± 1.79 g·d- 1) or HIGHFODMAP (38.65 ± 6.66 g·d- 1) diet for 7 days, with a one week washout period followed by a further 7 days on the alternate diet. Participants rated their gastrointestinal symptoms on an adapted version of the Irritable Bowel Syndrome-Severity Scoring System (IBS-SSS) questionnaire before and at the end of each dietary period. Perceived ability to exercise (frequency, intensity and duration) in relation to each dietary period was also rated using a visual analogue scale. Resting blood samples were collected prior to and on completion of each diet to determine plasma intestinal fatty acid binding protein (I-FABP) as a marker of acute GI injury. RESULTS Overall IBS-SSS score significantly reduced in the LOWFODMAP condition from 81.1 ± 16.4 to 31.3 ± 9.2 (arbitrary units; P = 0.004). Perceived exercise frequency (z = 2.309, P = 0.02) and intensity (z = 2.687, P = 0.007) was significantly improved following a short-term LOWFODMAP approach compared to HIGHFODMAP. No significant differences were reported between dietary conditions for plasma I-FABP (P > 0.05). CONCLUSIONS A short-term LOWFODMAP diet under free-living conditions reduced exercise-related GI symptoms and improved the perceived ability to exercise in otherwise healthy, recreational runners. These findings may be explained by a reduction in indigestible carbohydrates available for fermentation in the gut. The therapeutic benefits of LOWFODMAP diets in recreational and trained athletes during sustained training periods warrants further investigation.
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Affiliation(s)
- Melanie Wiffin
- Cambridge Centre for Sport and Exercise Sciences, School of Psychology and Sport Science, Anglia Ruskin University, Cambridge, UK
| | - Lee Smith
- Cambridge Centre for Sport and Exercise Sciences, School of Psychology and Sport Science, Anglia Ruskin University, Cambridge, UK
| | - Jose Antonio
- Department of Health and Human Performance, Nova Southeastern University, Davie, Florida, USA
| | - James Johnstone
- Cambridge Centre for Sport and Exercise Sciences, School of Psychology and Sport Science, Anglia Ruskin University, Cambridge, UK
| | - Liam Beasley
- Cambridge Centre for Sport and Exercise Sciences, School of Psychology and Sport Science, Anglia Ruskin University, Cambridge, UK
| | - Justin Roberts
- Cambridge Centre for Sport and Exercise Sciences, School of Psychology and Sport Science, Anglia Ruskin University, Cambridge, UK
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13
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Abstract
Fructose in the form of sucrose and high fructose corn syrup is absorbed by the intestinal transporter and mainly metabolized in the small intestine. However, excess intake of fructose overwhelms the absorptive capacity of the small intestine, leading to fructose malabsorption. Carbohydrate response element-binding protein (ChREBP) is a basic helix-loop-helix leucine zipper transcription factor that plays a key role in glycolytic and lipogenic gene expression in response to carbohydrate consumption. While ChREBP was initially identified as a glucose-responsive factor in the liver, recent evidence suggests that ChREBP is essential for fructoseinduced lipogenesis and gluconeogenesis in the small intestine as well as in the liver. We recently identified that the loss of ChREBP leads to fructose intolerance via insufficient induction of genes involved in fructose transport and metabolism in the intestine. As fructose consumption is increasing and closely associated with metabolic and gastrointestinal diseases, a comprehensive understanding of cellular fructose sensing and metabolism via ChREBP may uncover new therapeutic opportunities. In this mini review, we briefly summarize recent progress in intestinal fructose metabolism, regulation and function of ChREBP by fructose, and delineate the potential mechanisms by which excessive fructose consumption may lead to irritable bowel syndrome.
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Affiliation(s)
- Ho-Jae Lee
- Department of Biochemistry, Lee Gil Ya Cancer and Diabetes Institute, Gachon University College of Medicine, Incheon 21999, Korea
| | - Ji-Young Cha
- Department of Biochemistry, Lee Gil Ya Cancer and Diabetes Institute, Gachon University College of Medicine, Incheon 21999; Gachon Medical Institute, Gil Medical Center, Incheon 21565, Korea
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14
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Chemical biology probes of mammalian GLUT structure and function. Biochem J 2018; 475:3511-3534. [PMID: 30459202 PMCID: PMC6243331 DOI: 10.1042/bcj20170677] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 10/11/2018] [Accepted: 10/11/2018] [Indexed: 12/14/2022]
Abstract
The structure and function of glucose transporters of the mammalian GLUT family of proteins has been studied over many decades, and the proteins have fascinated numerous research groups over this time. This interest is related to the importance of the GLUTs as archetypical membrane transport facilitators, as key limiters of the supply of glucose to cell metabolism, as targets of cell insulin and exercise signalling and of regulated membrane traffic, and as potential drug targets to combat cancer and metabolic diseases such as type 2 diabetes and obesity. This review focusses on the use of chemical biology approaches and sugar analogue probes to study these important proteins.
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15
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Tang J, Fang Q, Shao R, Shen J, He J, Niu D, Lu L. Digital gene-expression profiling analysis of the fatty liver of Landes geese fed different supplemental oils. Gene 2018; 673:32-45. [DOI: 10.1016/j.gene.2018.05.122] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 05/08/2018] [Accepted: 05/31/2018] [Indexed: 01/18/2023]
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16
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Szablewski L. Distribution of glucose transporters in renal diseases. J Biomed Sci 2017; 24:64. [PMID: 28854935 PMCID: PMC5577680 DOI: 10.1186/s12929-017-0371-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Accepted: 08/23/2017] [Indexed: 02/06/2023] Open
Abstract
Kidneys play an important role in glucose homeostasis. Renal gluconeogenesis prevents hypoglycemia by releasing glucose into the blood stream. Glucose homeostasis is also due, in part, to reabsorption and excretion of hexose in the kidney.Lipid bilayer of plasma membrane is impermeable for glucose, which is hydrophilic and soluble in water. Therefore, transport of glucose across the plasma membrane depends on carrier proteins expressed in the plasma membrane. In humans, there are three families of glucose transporters: GLUT proteins, sodium-dependent glucose transporters (SGLTs) and SWEET. In kidney, only GLUTs and SGLTs protein are expressed. Mutations within genes that code these proteins lead to different renal disorders and diseases. However, diseases, not only renal, such as diabetes, may damage expression and function of renal glucose transporters.
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Affiliation(s)
- Leszek Szablewski
- Medical University of Warsaw, Chair & Department of General Biology & Parasitology, Center for Biostructure Research, 5 Chalubinskiego Str., 02-004, Warsaw, Poland.
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17
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Tuck CJ, Ross LA, Gibson PR, Barrett JS, Muir JG. Adding glucose to food and solutions to enhance fructose absorption is not effective in preventing fructose-induced functional gastrointestinal symptoms: randomised controlled trials in patients with fructose malabsorption. J Hum Nutr Diet 2016; 30:73-82. [PMID: 27600184 DOI: 10.1111/jhn.12409] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND In healthy individuals, the absorption of fructose in excess of glucose in solution is enhanced by the addition of glucose. The present study aimed to assess the effects of glucose addition to fructose or fructans on absorption patterns and genesis of gastrointestinal symptoms in patients with functional bowel disorders. METHODS Randomised, blinded, cross-over studies were performed in healthy subjects and functional bowel disorder patients with fructose malabsorption. The area-under-the-curve (AUC) was determined for breath hydrogen and symptom responses to: (i) six sugar solutions (fructose in solution) (glucose; sucrose; fructose; fructose + glucose; fructan; fructan + glucose) and (ii) whole foods (fructose in foods) containing fructose in excess of glucose given with and without additional glucose. Intake of fermentable short chain carbohydrates (FODMAPs; fermentable, oligo-, di-, monosaccharides and polyols) was controlled. RESULTS For the fructose in solution study, in 26 patients with functional bowel disorders, breath hydrogen was reduced after glucose was added to fructose compared to fructose alone [mean (SD) AUC 92 (107) versus 859 (980) ppm 4 h-1 , respectively; P = 0.034). Glucose had no effect on breath hydrogen response to fructans (P = 1.000). The six healthy controls showed breath hydrogen patterns similar to those with functional bowel disorders. No differences in symptoms were experienced with the addition of glucose, except more nausea when glucose was added to fructose (P = 0.049). In the fructose in foods study, glucose addition to whole foods containing fructose in excess of glucose in nine patients with functional bowel disorders and nine healthy controls had no significant effect on breath hydrogen production or symptom response. CONCLUSIONS The absence of a favourable response on symptoms does not support the concomitant intake of glucose with foods high in either fructose or fructans in patients with functional bowel disorders.
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Affiliation(s)
- C J Tuck
- Department of Gastroenterology, Monash University, The Alfred Hospital, Melbourne, VIC, Australia
| | - L A Ross
- Department of Gastroenterology, Monash University, The Alfred Hospital, Melbourne, VIC, Australia
| | - P R Gibson
- Department of Gastroenterology, Monash University, The Alfred Hospital, Melbourne, VIC, Australia
| | - J S Barrett
- Department of Gastroenterology, Monash University, The Alfred Hospital, Melbourne, VIC, Australia
| | - J G Muir
- Department of Gastroenterology, Monash University, The Alfred Hospital, Melbourne, VIC, Australia
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18
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Abstract
Incomplete intestinal absorption of fructose might lead to abdominal complaints such as pain, flatulence and diarrhoea. Whether defect fructose transporters such as GLUT5 or GLUT2 are involved in the pathogenesis of fructose malabsorption is a matter of debate. The hydrogen production by colonic bacteria is used for diagnosis with the hydrogen breath test. However, the appropriate fructose test dose for correct diagnosis is unclear. Subjects with fructose malabsorption show increased breath hydrogen levels and abdominal symptoms after fructose administration but do not report any symptoms when fructose is given together with glucose. This beneficial effect of glucose, however, cannot be explained yet but might be used for clinical care of these subjects.
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Affiliation(s)
- Karolin Ebert
- Pädiatrische Ernährungsmedizin, Klinikum rechts der Isar (MRI), Technische Universität München (TUM), Gregor-MendelStr. 2, 85354, Freising, Germany. .,Else Kröner-Fresenius-Zentrum für Ernährungsmedizin (EKFZ), Technische Universität München (TUM), Gregor-MendelStr. 2, 85354, Freising, Germany. .,Zentralinstitut für Ernährungs- und Lebensmittelforschung (ZIEL), Technische Universität München (TUM), Gregor-MendelStr. 2, 85354, Freising, Germany.
| | - Heiko Witt
- Pädiatrische Ernährungsmedizin, Klinikum rechts der Isar (MRI), Technische Universität München (TUM), Gregor-MendelStr. 2, 85354, Freising, Germany. .,Else Kröner-Fresenius-Zentrum für Ernährungsmedizin (EKFZ), Technische Universität München (TUM), Gregor-MendelStr. 2, 85354, Freising, Germany. .,Zentralinstitut für Ernährungs- und Lebensmittelforschung (ZIEL), Technische Universität München (TUM), Gregor-MendelStr. 2, 85354, Freising, Germany.
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19
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Nomura N, Verdon G, Kang HJ, Shimamura T, Nomura Y, Sonoda Y, Hussien SA, Qureshi AA, Coincon M, Sato Y, Abe H, Nakada-Nakura Y, Hino T, Arakawa T, Kusano-Arai O, Iwanari H, Murata T, Kobayashi T, Hamakubo T, Kasahara M, Iwata S, Drew D. Structure and mechanism of the mammalian fructose transporter GLUT5. Nature 2015; 526:397-401. [PMID: 26416735 PMCID: PMC4618315 DOI: 10.1038/nature14909] [Citation(s) in RCA: 167] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Accepted: 07/14/2015] [Indexed: 02/02/2023]
Abstract
The altered activity of the fructose transporter GLUT5, an isoform of the facilitated-diffusion glucose transporter family, has been linked to disorders such as type 2 diabetes and obesity. GLUT5 is also overexpressed in certain tumor cells and inhibitors are potential drugs for these conditions. Here, we describe the crystal structure of GLUT5 from Rattus norvegicus and Bos taurus in open outward- and open inward-facing conformations, respectively. GLUT5 has a major facilitator superfamily fold like other homologous monosaccharide transporters. Based on a comparison of the inward-facing structures of GLUT5 and human GLUT1, a ubiquitous glucose transporter, we show that a single point mutation is enough to switch the substrate binding preference of GLUT5 from fructose to glucose. A comparison of the substrate-free structures of GLUT5 with occluded substrate-bound structures of XylE suggests that, besides global rocker-switch like re-orientation of the bundles, local asymmetric rearrangements of C-terminal bundle helices TMs 7 and 10 underlie a “gated-pore” transport mechanism in such monosaccharide transporters.
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Affiliation(s)
- Norimichi Nomura
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan.,Japan Science and Technology Agency, ERATO, Iwata Human Receptor Crystallography Project, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.,Japan Science and Technology Agency, Research Acceleration Program, Membrane Protein Crystallography Project, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Grégory Verdon
- Division of Molecular Biosciences, Imperial College London, London, SW7 2AZ, U.K.,Membrane Protein Laboratory, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Chilton, Oxfordshire, OX11 0DE, U.K.,Research Complex at Harwell Rutherford, Appleton Laboratory, Harwell, Oxford, Didcot, Oxfordshire, OX11 0FA, U.K
| | - Hae Joo Kang
- Division of Molecular Biosciences, Imperial College London, London, SW7 2AZ, U.K.,Membrane Protein Laboratory, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Chilton, Oxfordshire, OX11 0DE, U.K.,Research Complex at Harwell Rutherford, Appleton Laboratory, Harwell, Oxford, Didcot, Oxfordshire, OX11 0FA, U.K
| | - Tatsuro Shimamura
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan.,Japan Science and Technology Agency, ERATO, Iwata Human Receptor Crystallography Project, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.,Japan Science and Technology Agency, Research Acceleration Program, Membrane Protein Crystallography Project, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Yayoi Nomura
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan.,Japan Science and Technology Agency, ERATO, Iwata Human Receptor Crystallography Project, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.,Japan Science and Technology Agency, Research Acceleration Program, Membrane Protein Crystallography Project, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Yo Sonoda
- Division of Molecular Biosciences, Imperial College London, London, SW7 2AZ, U.K
| | - Saba Abdul Hussien
- Centre for Biomembrane Research, Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Aziz Abdul Qureshi
- Centre for Biomembrane Research, Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Mathieu Coincon
- Centre for Biomembrane Research, Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Yumi Sato
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan.,Japan Science and Technology Agency, Research Acceleration Program, Membrane Protein Crystallography Project, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Hitomi Abe
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan
| | - Yoshiko Nakada-Nakura
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan.,Japan Science and Technology Agency, Research Acceleration Program, Membrane Protein Crystallography Project, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Tomoya Hino
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan.,Japan Science and Technology Agency, ERATO, Iwata Human Receptor Crystallography Project, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Takatoshi Arakawa
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan.,Japan Science and Technology Agency, ERATO, Iwata Human Receptor Crystallography Project, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Osamu Kusano-Arai
- Department of Quantitative Biology and Medicine, Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
| | - Hiroko Iwanari
- Department of Quantitative Biology and Medicine, Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
| | - Takeshi Murata
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan.,Japan Science and Technology Agency, ERATO, Iwata Human Receptor Crystallography Project, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.,Japan Science and Technology Agency, Research Acceleration Program, Membrane Protein Crystallography Project, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.,Systems and Structural Biology Center, RIKEN, 1-7-22 Suehirocho, Tsurumi-ku, Yokohama 230-0045, Japan
| | - Takuya Kobayashi
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan.,Japan Science and Technology Agency, ERATO, Iwata Human Receptor Crystallography Project, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.,Japan Science and Technology Agency, Research Acceleration Program, Membrane Protein Crystallography Project, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Takao Hamakubo
- Department of Quantitative Biology and Medicine, Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
| | - Michihiro Kasahara
- Laboratory of Biophysics, School of Medicine, Teikyo University, Hachioji, Tokyo 192-0395, Japan
| | - So Iwata
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan.,Japan Science and Technology Agency, ERATO, Iwata Human Receptor Crystallography Project, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.,Japan Science and Technology Agency, Research Acceleration Program, Membrane Protein Crystallography Project, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.,Division of Molecular Biosciences, Imperial College London, London, SW7 2AZ, U.K.,Membrane Protein Laboratory, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Chilton, Oxfordshire, OX11 0DE, U.K.,Research Complex at Harwell Rutherford, Appleton Laboratory, Harwell, Oxford, Didcot, Oxfordshire, OX11 0FA, U.K.,Systems and Structural Biology Center, RIKEN, 1-7-22 Suehirocho, Tsurumi-ku, Yokohama 230-0045, Japan
| | - David Drew
- Division of Molecular Biosciences, Imperial College London, London, SW7 2AZ, U.K.,Centre for Biomembrane Research, Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
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20
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Kikuta S, Nakamura Y, Hattori M, Sato R, Kikawada T, Noda H. Herbivory-induced glucose transporter gene expression in the brown planthopper, Nilaparvata lugens. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2015; 64:60-67. [PMID: 26226652 DOI: 10.1016/j.ibmb.2015.07.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 06/30/2015] [Accepted: 07/22/2015] [Indexed: 06/04/2023]
Abstract
Nilaparvata lugens, the brown planthopper (BPH) feeds on rice phloem sap, containing high amounts of sucrose as a carbon source. Nutrients such as sugars in the digestive tract are incorporated into the body cavity via transporters with substrate selectivity. Eighteen sugar transporter genes of BPH (Nlst) were reported and three transporters have been functionally characterized. However, individual characteristics of NlST members associated with sugar transport remain poorly understood. Comparative gene expression analyses using oligo-microarray and quantitative RT-PCR revealed that the sugar transporter gene Nlst16 was markedly up-regulated during BPH feeding. Expression of Nlst16 was induced 2 h after BPH feeding on rice plants. Nlst16, mainly expressed in the midgut, appears to be involved in carbohydrate incorporation from the gut cavity into the hemolymph. Nlst1 (NlHT1), the most highly expressed sugar transporter gene in the midgut was not up-regulated during BPH feeding. The biochemical function of NlST16 was shown as facilitative glucose transport along gradients. Glucose uptake activity by NlST16 was higher than that of NlST1 in the Xenopus oocyte expression system. At least two NlST members are responsible for glucose uptake in the BPH midgut, suggesting that the midgut of BPH is equipped with various types of transporters having diversified manner for sugar uptake.
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Affiliation(s)
- Shingo Kikuta
- National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8634, Japan; Department of Integrated Biosciences, Graduate School of Frontier Science, The University of Tokyo, Kashiwa, Chiba 277-8562, Japan; Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan.
| | - Yuki Nakamura
- National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8634, Japan
| | - Makoto Hattori
- National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8634, Japan
| | - Ryoichi Sato
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Takahiro Kikawada
- National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8634, Japan; Department of Integrated Biosciences, Graduate School of Frontier Science, The University of Tokyo, Kashiwa, Chiba 277-8562, Japan
| | - Hiroaki Noda
- National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8634, Japan; Department of Integrated Biosciences, Graduate School of Frontier Science, The University of Tokyo, Kashiwa, Chiba 277-8562, Japan.
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21
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Kerimi A, Williamson G. The cardiovascular benefits of dark chocolate. Vascul Pharmacol 2015; 71:11-5. [PMID: 26026398 DOI: 10.1016/j.vph.2015.05.011] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 05/11/2015] [Accepted: 05/20/2015] [Indexed: 11/16/2022]
Abstract
Dark chocolate contains many biologically active components, such as catechins, procyanidins and theobromine from cocoa, together with added sucrose and lipids. All of these can directly or indirectly affect the cardiovascular system by multiple mechanisms. Intervention studies on healthy and metabolically-dysfunctional volunteers have suggested that cocoa improves blood pressure, platelet aggregation and endothelial function. The effect of chocolate is more convoluted since the sucrose and lipid may transiently and negatively impact on endothelial function, partly through insulin signalling and nitric oxide bioavailability. However, few studies have attempted to dissect out the role of the individual components and have not explored their possible interactions. For intervention studies, the situation is complex since suitable placebos are often not available, and some benefits may only be observed in individuals showing mild metabolic dysfunction. For chocolate, the effects of some of the components, such as sugar and epicatechin on FMD, may oppose each other, or alternatively in some cases may act together, such as theobromine and epicatechin. Although clearly cocoa provides some cardiovascular benefits according to many human intervention studies, the exact components, their interactions and molecular mechanisms are still under debate.
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Affiliation(s)
- Asimina Kerimi
- School of Food Science and Nutrition, Faculty of Maths and Physical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Gary Williamson
- School of Food Science and Nutrition, Faculty of Maths and Physical Sciences, University of Leeds, Leeds LS2 9JT, UK.
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22
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Low-FODMAP Diet for Irritable Bowel Syndrome: Is It Ready for Prime Time? Dig Dis Sci 2015; 60:1169-77. [PMID: 25410635 DOI: 10.1007/s10620-014-3436-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 11/11/2014] [Indexed: 12/15/2022]
Abstract
Irritable bowel syndrome (IBS) is a chronic gastrointestinal disease, which adversely affects the quality of life. Its prevalence has been reported to be around 10-15 % in North America and constitutes the most common cause for gastroenterology referral. Unfortunately, the pathophysiology of IBS is not completely understood. Not surprisingly, the management strategies can leave the patients with inadequate symptom control, making IBS a debilitating gastrointestinal syndrome. Dietary interventions as a treatment strategy for IBS have been recently evaluated. One such intervention includes dietary restriction of fermentable oligo-, di-, and monosaccharides and polyols (FODMAPs). FODMAPs define a group of short-chain carbohydrates that are incompletely absorbed in small intestine and later fermented in the colon. Evidence in the form of randomized controlled trials and observational studies have evaluated the mechanism of action and efficacy of low-FODMAP diet. This dietary intervention has showed promising results in symptom reduction in IBS patients. However, latest trials have also shown that the low-FODMAP diet is associated with marked changes in gut microbiota specifically reduction in microbiota with prebiotic properties. Implications of such changes on gastrointestinal health need to be further evaluated in future trials.
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Abstract
Soluble sugars serve five main purposes in multicellular organisms: as sources of carbon skeletons, osmolytes, signals, and transient energy storage and as transport molecules. Most sugars are derived from photosynthetic organisms, particularly plants. In multicellular organisms, some cells specialize in providing sugars to other cells (e.g., intestinal and liver cells in animals, photosynthetic cells in plants), whereas others depend completely on an external supply (e.g., brain cells, roots and seeds). This cellular exchange of sugars requires transport proteins to mediate uptake or release from cells or subcellular compartments. Thus, not surprisingly, sugar transport is critical for plants, animals, and humans. At present, three classes of eukaryotic sugar transporters have been characterized, namely the glucose transporters (GLUTs), sodium-glucose symporters (SGLTs), and SWEETs. This review presents the history and state of the art of sugar transporter research, covering genetics, biochemistry, and physiology-from their identification and characterization to their structure, function, and physiology. In humans, understanding sugar transport has therapeutic importance (e.g., addressing diabetes or limiting access of cancer cells to sugars), and in plants, these transporters are critical for crop yield and pathogen susceptibility.
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Affiliation(s)
- Li-Qing Chen
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305;
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24
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Tuck CJ, Muir JG, Barrett JS, Gibson PR. Fermentable oligosaccharides, disaccharides, monosaccharides and polyols: role in irritable bowel syndrome. Expert Rev Gastroenterol Hepatol 2014; 8:819-34. [PMID: 24830318 DOI: 10.1586/17474124.2014.917956] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Irritable bowel syndrome (IBS) was previously left poorly treated despite its high prevalence and cost. Over the past decade, significant research has been conducted providing new dietary strategies for IBS management. The 'low fermentable oligosaccharides, disaccharides, monosaccharides and polyols diet' has shown symptom improvement in 68-76% of patients. Randomized, controlled trials have now proven its efficacy. The diet, low in poorly absorbed and fermentable carbohydrates, uses dietary restriction and re-challenge to determine individual tolerance to various short-chain carbohydrates. However there may be potential detrimental effects of the diet in the long term, due to potential changes to the gastrointestinal microbiota. Appropriate dietary education and management of the diet is imperative. Future research should focus on the relevance of changes to the microbiota and ways to liberalize the dietary restrictions.
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Affiliation(s)
- Caroline J Tuck
- Department of Gastroenterology, Monash University and Alfred Health, Level 6, The Alfred Centre, 99 Commercial Road, Melbourne, Victoria, 3004 Australia
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25
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Leung L, Kang J, Rayyan E, Bhakta A, Barrett B, Larsen D, Jelinek R, Willey J, Cochran S, Broderick TL, Al-Nakkash L. Decreased basal chloride secretion and altered cystic fibrosis transmembrane conductance regulatory protein, Villin, GLUT5 protein expression in jejunum from leptin-deficient mice. Diabetes Metab Syndr Obes 2014; 7:321-30. [PMID: 25092993 PMCID: PMC4112754 DOI: 10.2147/dmso.s63714] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Patients with diabetes and obesity are at increased risk of developing disturbances in intestinal function. In this study, we characterized jejunal function in the clinically relevant leptin-deficient ob/ob mouse, a model of diabetes and obesity. We measured transepithelial short circuit current (Isc), across freshly isolated segments of jejunum from 12-week-old ob/ob and lean C57BL/6J (female and male) mice. The basal Isc was significantly decreased (~30%) in the ob/ob mice (66.5±5.7 μA/cm(2) [n=20]) (P< 0.05) compared with their lean counterparts (95.1±9.1 μA/cm(2) [n=19]). Inhibition with clotrimazole (100 μM, applied bilaterally) was significantly reduced in the ob/ob mice (-7.92%±3.67% [n=15]) (P<0.05) compared with the lean mice (10.44%±7.92% [n=15]), indicating a decreased contribution of Ca(2+)-activated K(+) (KCa) channels in the ob/ob mice. Inhibition with ouabain (100 μM, applied serosally) was significantly reduced in the ob/ob mice (1.40%±3.61%, n=13) (P< 0.05) versus the lean mice (18.93%±3.76% [n=18]), suggesting a potential defect in the Na(+)/K(+)-adenosine triphosphate (ATP)ase pump with leptin-deficiency. Expression of cystic fibrosis transmembrane conductance regulatory protein (CFTR) (normalized to glyceraldehyde-3-phosphate dehydrogenase [GAPDH]) was significantly decreased ~twofold (P<0.05) in the ob/ob mice compared with the leans, whilst crypt depth was unchanged. Villi length was significantly increased by ~25% (P<0.05) in the ob/ob mice compared with the leans and was associated with an increase in Villin and GLUT5 expression. GLUT2 and SGLT-1 expression were both unchanged. Our data suggests that reduced basal jejunal Isc in ob/ob mice is likely a consequence of reduced CFTR expression and decreased activity of the basolateral KCa channel and Na(+)/K(+)-ATPase. Understanding intestinal dysfunctions in ob/ob jejunum may allow for the development of novel drug targets to treat obesity and diabetes.
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Affiliation(s)
- Lana Leung
- Department of Physiology, Arizona College of Osteopathic Medicine, Midwestern University, Glendale, AZ, USA
| | - Jonathan Kang
- Department of Physiology, Arizona College of Osteopathic Medicine, Midwestern University, Glendale, AZ, USA
| | - Esa Rayyan
- Department of Physiology, Arizona College of Osteopathic Medicine, Midwestern University, Glendale, AZ, USA
| | - Ashesh Bhakta
- Department of Physiology, Arizona College of Osteopathic Medicine, Midwestern University, Glendale, AZ, USA
| | - Brennan Barrett
- Department of Physiology, Arizona College of Osteopathic Medicine, Midwestern University, Glendale, AZ, USA
| | - David Larsen
- Department of Physiology, Arizona College of Osteopathic Medicine, Midwestern University, Glendale, AZ, USA
| | - Ryan Jelinek
- Department of Physiology, Arizona College of Osteopathic Medicine, Midwestern University, Glendale, AZ, USA
| | - Justin Willey
- Department of Physiology, Arizona College of Osteopathic Medicine, Midwestern University, Glendale, AZ, USA
| | - Scott Cochran
- Department of Physiology, Arizona College of Osteopathic Medicine, Midwestern University, Glendale, AZ, USA
| | - Tom L Broderick
- Department of Physiology, Arizona College of Osteopathic Medicine, Midwestern University, Glendale, AZ, USA
| | - Layla Al-Nakkash
- Department of Physiology, Arizona College of Osteopathic Medicine, Midwestern University, Glendale, AZ, USA
- Correspondence: Layla Al-Nakkash, Department of Physiology, Midwestern University, 19555 N 59th Avenue, Glendale, AZ, 85308, USA, Tel +1 623 572 3719, Fax +1 623 572 3673, Email
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Barrenetxe J, Sánchez O, Barber A, Gascón S, Rodríguez-Yoldi MJ, Lostao MP. TNFα regulates sugar transporters in the human intestinal epithelial cell line Caco-2. Cytokine 2013; 64:181-7. [PMID: 23910014 DOI: 10.1016/j.cyto.2013.07.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 06/10/2013] [Accepted: 07/02/2013] [Indexed: 01/25/2023]
Abstract
PURPOSE During intestinal inflammation TNFα levels are increased and as a consequence malabsorption of nutrients may occur. We have previously demonstrated that TNFα inhibits galactose, fructose and leucine intestinal absorption in animal models. In continuation with our work, the purpose of the present study was to investigate in the human intestinal epithelial cell line Caco-2, the effect of TNFα on sugar transport and to identify the intracellular mechanisms involved. METHODS Caco-2 cells were grown on culture plates and pre-incubated during different periods with various TNFα concentrations before measuring the apical uptake of galactose, α-methyl-glucoside (MG) or fructose for 15 min. To elucidate the signaling pathway implicated, cells were pre-incubated for 30min with the PKA inhibitor H-89 or the PKC inhibitor chelerythrine, before measuring the sugar uptake. The expression in the apical membrane of the transporters implicated in the sugars uptake process (SGLT1 and GLUT5) was determined by Western blot. RESULTS TNFα inhibited 0.1mM MG uptake after pre-incubation of the cells for 6-48h with the cytokine and in the absence of cytokine pre-incubation. In contrast, 5mM fructose uptake was stimulated by TNFα only after long pre-incubation times (24 and 48 h). These effects were mediated by the binding of the cytokine to its specific receptor TNFR1, present in the apical membrane of the Caco-2 cells. Analysis of the expression of the MG and fructose transporters at the brush border membrane of the cells, after 24h pre-incubation with the cytokine, revealed decrease on the amount of SGLT1 and increase on the amount of GLUT5 proteins. Short-term inhibition of MG transport by TNFα was not modified by H-89 but was blocked by chelerythrine. CONCLUSIONS SGLT1 and GLUT5 expression in the plasma membrane is regulated by TNFα in the human epithelial cell line Caco-2 cells, leading to alteration on sugars transport, suggesting that TNFα could be considered as a physiological local regulator of nutrients absorption in response to an intestinal inflammatory status.
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Affiliation(s)
- Jaione Barrenetxe
- Department of Nutrition, Food Science and Physiology, University of Navarra, Pamplona 31008, Spain.
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27
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Jones HF, Butler RN, Moore DJ, Brooks DA. Developmental changes and fructose absorption in children: effect on malabsorption testing and dietary management. Nutr Rev 2013; 71:300-9. [DOI: 10.1111/nure.12020] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Affiliation(s)
| | | | - David J Moore
- Gastroenterology Unit; Women's & Children's Hospital; Adelaide; South Australia; Australia
| | - Doug A Brooks
- Mechanisms in Cell Biology and Diseases Research Group; School of Pharmacy and Medical Sciences; Sansom Institute for Health Research; University of South Australia; Adelaide; South Australia; Australia
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28
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McQuade DT, Plutschack MB, Seeberger PH. Passive fructose transporters in disease: a molecular overview of their structural specificity. Org Biomol Chem 2013; 11:4909-20. [DOI: 10.1039/c3ob40805a] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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29
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Zhao FQ, Keating AF. Functional properties and genomics of glucose transporters. Curr Genomics 2011; 8:113-28. [PMID: 18660845 DOI: 10.2174/138920207780368187] [Citation(s) in RCA: 363] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2006] [Revised: 12/08/2006] [Accepted: 12/17/2007] [Indexed: 12/17/2022] Open
Abstract
Glucose is the major energy source for mammalian cells as well as an important substrate for protein and lipid synthesis. Mammalian cells take up glucose from extracellular fluid into the cell through two families of structurallyrelated glucose transporters. The facilitative glucose transporter family (solute carriers SLC2A, protein symbol GLUT) mediates a bidirectional and energy-independent process of glucose transport in most tissues and cells, while the NaM(+)/glucose cotransporter family (solute carriers SLC5A, protein symbol SGLT) mediates an active, Na(+)-linked transport process against an electrochemical gradient. The GLUT family consists of thirteen members (GLUT1-12 and HMIT). Phylogenetically, the members of the GLUT family are split into three classes based on protein similarities. Up to now, at least six members of the SGLT family have been cloned (SGLT1-6). In this review, we report both the genomic structure and function of each transporter as well as intra-species comparative genomic analysis of some of these transporters. The affinity for glucose and transport kinetics of each transporter differs and ranges from 0.2 to 17mM. The ability of each protein to transport alternative substrates also differs and includes substrates such as fructose and galactose. In addition, the tissue distribution pattern varies between species. There are different regulation mechanisms of these transporters. Characterization of transcriptional control of some of the gene promoters has been investigated and alternative promoter usage to generate different protein isoforms has been demonstrated. We also introduce some pathophysiological roles of these transporters in human.
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Affiliation(s)
- Feng-Qi Zhao
- Lactation and Mammary Gland Biology Group, Department of Animal Science, University of Vermont, Burlington, VT, USA
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30
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Jones HF, Butler RN, Brooks DA. Intestinal fructose transport and malabsorption in humans. Am J Physiol Gastrointest Liver Physiol 2011; 300:G202-6. [PMID: 21148401 DOI: 10.1152/ajpgi.00457.2010] [Citation(s) in RCA: 109] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Fructose is a hexose sugar that is being increasingly consumed in its monosaccharide form. Patients who exhibit fructose malabsorption can present with gastrointestinal symptoms that include chronic diarrhea and abdominal pain. However, with no clearly established gastrointestinal mechanism for fructose malabsorption, patient analysis by the proxy of a breath hydrogen test (BHT) is controversial. The major transporter for fructose in intestinal epithelial cells is thought to be the facilitative transporter GLUT5. Consistent with a facilitative transport system, we show here by analysis of past studies on healthy adults that there is a significant relationship between fructose malabsorption and fructose dose (r = 0.86, P < 0.001). Thus there is a dose-dependent and limited absorption capacity even in healthy individuals. Changes in fructose malabsorption with age have been observed in human infants, and this may parallel the developmental regulation of GLUT5 expression. Moreover, a GLUT5 knockout mouse has displayed the hallmarks associated with profound fructose malabsorption. Fructose malabsorption appears to be partially modulated by the amount of glucose ingested. Although solvent drag and passive diffusion have been proposed to explain the effect of glucose on fructose malabsorption, this could possibly be a result of the facilitative transporter GLUT2. GLUT5 and GLUT2 mRNA have been shown to be rapidly upregulated by the presence of fructose and GLUT2 mRNA is also upregulated by glucose, but in humans the distribution and role of GLUT2 in the brush border membrane are yet to be definitively decided. Understanding the relative roles of these transporters in humans will be crucial for establishing a mechanistic basis for fructose malabsorption in gastrointestinal patients.
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Affiliation(s)
- Hilary F Jones
- Mechanisms in Cell Biology and Disease Research Group, Sansom Institute for Health Research, Univ. of South Australia, South Australia 5001, Australia
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31
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Augustin R. The protein family of glucose transport facilitators: It's not only about glucose after all. IUBMB Life 2010; 62:315-33. [PMID: 20209635 DOI: 10.1002/iub.315] [Citation(s) in RCA: 167] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The protein family of facilitative glucose transporters comprises 14 isoforms that share common structural features such as 12 transmembrane domains, N- and C-termini facing the cytoplasm of the cell, and a N-glycosylation side either within the first or fifth extracellular loop. Based on their sequence homology, three classes can be distinguished: class I includes GLUT1-4 and GLUT14, class II the "odd transporters" GLUT5, 7, 9, 11, and class III the "even transporters" GLUT6, 8, 10, 12 and the proton driven myoinositol transporter HMIT (or GLUT13). With the cloning and characterization of the more recent class II and III isoforms, it became apparent that despite their structural similarities, the different isoforms not only show a distinct tissue-specific expression pattern but also show distinct characteristics such as alternative splicing, specific (sub)cellular localization, and affinities for a spectrum of substrates. This review summarizes the current understanding of the physiological role for the various transport facilitators based on human genetically inherited disorders or single-nucleotide polymorphisms and knockout mice models. The emphasis of the review will be on the potential functional role of the more recent isoforms.
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Affiliation(s)
- Robert Augustin
- Department of Cardiometabolic Diseases Research, Boehringer-Ingelheim Pharma GmbH&Co KG, Biberach a.d. Riss, Germany.
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32
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Douard V, Ferraris RP. Regulation of the fructose transporter GLUT5 in health and disease. Am J Physiol Endocrinol Metab 2008; 295:E227-37. [PMID: 18398011 PMCID: PMC2652499 DOI: 10.1152/ajpendo.90245.2008] [Citation(s) in RCA: 296] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2008] [Accepted: 03/27/2008] [Indexed: 12/11/2022]
Abstract
Fructose is now such an important component of human diets that increasing attention is being focused on the fructose transporter GLUT5. In this review, we describe the regulation of GLUT5 not only in the intestine and testis, where it was first discovered, but also in the kidney, skeletal muscle, fat tissue, and brain where increasing numbers of cell types have been found to have GLUT5. GLUT5 expression levels and fructose uptake rates are also significantly affected by diabetes, hypertension, obesity, and inflammation and seem to be induced during carcinogenesis, particularly in the mammary glands. We end by highlighting research areas that should yield information needed to better understand the role of GLUT5 during normal development, metabolic disturbances, and cancer.
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Affiliation(s)
- Veronique Douard
- Department of Pharmacology and Physiology, UMDNJ-New Jersey Medical School, 185 South Orange Avenue, Newark, NJ 07101, USA
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Le Gall M, Tobin V, Stolarczyk E, Dalet V, Leturque A, Brot-Laroche E. Sugar sensing by enterocytes combines polarity, membrane bound detectors and sugar metabolism. J Cell Physiol 2007; 213:834-43. [PMID: 17786952 DOI: 10.1002/jcp.21245] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Sugar consumption and subsequent sugar metabolism are known to regulate the expression of genes involved in intestinal sugar absorption and delivery. Here we investigate the hypothesis that sugar-sensing detectors in membranes facing the intestinal lumen or the bloodstream can also modulate intestinal sugar absorption. We used wild-type and GLUT2-null mice, to show that dietary sugars stimulate the expression of sucrase-isomaltase (SI) and L-pyruvate kinase (L-PK) by GLUT2-dependent mechanisms, whereas the expression of GLUT5 and SGLT1, did not rely on the presence of GLUT2. By providing sugar metabolites, sugar transporters, including GLUT2, fuelled a sensing pathway. In Caco2/TC7 enterocytes, we could disconnect the sensing triggered by detector from that produced by metabolism, and found that GLUT2 generated a metabolism-independent pathway to stimulate the expression of SI and L-PK. In cultured enterocytes, both apical and basolateral fructose could increase the expression of GLUT5, conversely, basolateral sugar administration could stimulate the expression of GLUT2. Finally, we located the sweet-taste receptors T1R3 and T1R2 in plasma membranes, and we measured their cognate G alpha Gustducin mRNA levels. Furthermore, we showed that a T1R3 inhibitor altered the fructose-induced expression of SGLT1, GLUT5, and L-PK. Intestinal gene expression is thus controlled by a combination of at least three sugar-signaling pathways triggered by sugar metabolites and membrane sugar receptors that, according to membrane location, determine sugar-sensing polarity. This provides a rationale for how intestine adapts sugar delivery to blood and dietary sugar provision.
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Affiliation(s)
- Maude Le Gall
- INSERM, UMR S 872, Centre de Recherche des Cordeliers, Paris, France.
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Caccia S, Casartelli M, Grimaldi A, Losa E, de Eguileor M, Pennacchio F, Giordana B. Unexpected similarity of intestinal sugar absorption by SGLT1 and apical GLUT2 in an insect (Aphidius ervi,Hymenoptera) and mammals. Am J Physiol Regul Integr Comp Physiol 2007; 292:R2284-91. [PMID: 17322115 DOI: 10.1152/ajpregu.00847.2006] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sugars are critical substrates for insect metabolism, but little is known about the transporters and epithelial routes that ensure their constant supply from dietary resources. We have characterized glucose and fructose uptakes across the apical and basolateral membranes of the isolated larval midgut of the aphid parasitoid Aphidius ervi. The uptake of radiolabeled glucose at the basal side of the epithelium was almost suppressed by 200 μM cytochalasin B, uninhibited by phlorizin, and showed the following decreasing rank of specificity for the tested substrates: glucose > glucosamine > fructose, with no recognition of galactose. These functional properties well agree with the expression of GLUT2-like transporters in this membrane. When the apical surface of the epithelium was also exposed to the labeled medium, a cation-dependent glucose uptake, inhibited by 10 μM phlorizin and by an excess of galactose, was detected suggesting the presence in the apical membrane of a cation-dependent cotransporter. Radiolabeled fructose uptakes were only partially inhibited by cytochalasin B. SGLT1-like and GLUT5-like transporters were detected in the apical membranes of the epithelial cell by immunocytochemical experiments. These results, along with the presence of GLUT2-like transporters both in the apical and basolateral cell membranes of the midgut, as we recently demonstrated, allow us to conclude that the model for sugar transepithelial transport in A. ervi midgut appears to be unexpectedly similar to that recently proposed for sugar intestinal absorption in mammals.
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Affiliation(s)
- S Caccia
- Dipartimento di Biologia, Università di Milano, via Celoria 26, 20133 Milano, Italy
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Meakin PJ, Fowler MJ, Rathbone AJ, Allen LM, Ransom BR, Ray DE, Brown AM. Fructose metabolism in the adult mouse optic nerve, a central white matter tract. J Cereb Blood Flow Metab 2007; 27:86-99. [PMID: 16670697 DOI: 10.1038/sj.jcbfm.9600322] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Our recent report that fructose supported the metabolism of some, but not all axons, in the adult mouse optic nerve prompted us to investigate in detail fructose metabolism in this tissue, a typical central white matter tract, as these data imply efficient fructose metabolism in the central nervous system (CNS). In artificial cerebrospinal fluid containing 10 mmol/L glucose or 20 mmol/L fructose, the stimulus-evoked compound action potential (CAP) recorded from the optic nerve consisted of three stable peaks. Replacing 10 mmol/L glucose with 10 mmol/L fructose, however, caused delayed loss of the 1st CAP peak (the 2nd and 3rd CAP peaks were unaffected). Glycogen-derived metabolic substrate(s) temporarily sustained the 1st CAP peak in 10 mmol/L fructose, as depletion of tissue glycogen by a prior period of aglycaemia or high-frequency CAP discharge rendered fructose incapable of supporting the 1st CAP peak. Enzyme assays showed the presence of both hexokinase and fructokinase (both of which can phosphorylate fructose) in the optic nerve. In contrast, only hexokinase was expressed in cerebral cortex. Hexokinase in optic nerve had low affinity and low capacity with fructose as substrate, whereas fructokinase displayed high affinity and high capacity for fructose. These findings suggest an explanation for the curious fact that the fast conducting axons comprising the 1st peak of the CAP are not supported in 10 mmol/L fructose medium; these axons probably do not express fructokinase, a requirement for efficient fructose metabolism.
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Affiliation(s)
- Paul J Meakin
- MRC Applied Neuroscience Group, School of Biomedical Sciences, Queens Medical Centre, University of Nottingham, Nottingham, UK
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Abstract
Carbohydrates are an important component of the diet. The carbohydrates that we ingest range from simple monosaccharides (glucose, fructose and galactose) to disaccharides (lactose, sucrose) to complex polysaccharides. Most carbohydrates are digested by salivary and pancreatic amylases, and are further broken down into monosaccharides by enzymes in the brush border membrane (BBM) of enterocytes. For example, lactase-phloridzin hydrolase and sucrase-isomaltase are two disaccharidases involved in the hydrolysis of nutritionally important disaccharides. Once monosaccharides are presented to the BBM, mature enterocytes expressing nutrient transporters transport the sugars into the enterocytes. This paper reviews the early studies that contributed to the development of a working model of intestinal sugar transport, and details the recent advances made in understanding the process by which sugars are absorbed in the intestine.
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Affiliation(s)
- Laurie A Drozdowski
- Division of Gastroenterology, Department of Medicine, University of Alberta, 5150 Dentistry Pharmacy Building, Edmonton, Alberta T6G 2N8, Canada.
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Hakata T, Ito K, Horie T. Enhanced absorption of 3-O-methyl glucose following gastrointestinal injury induced by repeated oral administration of 5-FU in mice. J Pharm Sci 2006; 94:1713-22. [PMID: 15986457 DOI: 10.1002/jps.20388] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The absorption of nutrients is mainly mediated by specific carriers and generally retarded following gastrointestinal injury. The aim of this study was to assess the effect of repeated oral administration of 5-fluorouracil (5-FU) on the intestinal absorption of glucose by using 3-O-methyl-D-glucose (3-OMG), a glucose analogue that is not metabolized, as a probe. Repeated administration of 5-FU (60 mg/kg/day for 3 days) readily induced intestinal mucosal injury assessed by visual observation and loss of intestinal wet weight. At the same time, the carrier-dependent absorption clearance of 3-OMG was increased 1.8-fold, while the carrier-independent absorption assessed by L-glucose transport was not affected. Phloretin, a glucose transporter 2 (GLUT2) inhibitor, completely abolished the absorption of 3-OMG in both control and 5-FU-treated mice, indicating the specific effect on the carrier-dependent process. Protein and mRNA expressions of GLUT2 were significantly higher in 5-FU-treated mice compared to the control mice. Sodium (Na(+)) glucose co-transporter 1 (SGLT1) expressions were also moderately elevated in 5-FU-treated mice. Concomitantly, the uptake of D-glucose into both isolated brush border and basolateral membrane vesicles was significantly increased. These results indicate that repeated oral administration of 5-FU did not hamper, but unexpectedly induced, SGLT1 and GLUT2 expression to enhance glucose absorption.
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Affiliation(s)
- Tomoko Hakata
- Laboratory of Biopharmaceutics, Graduate School of Pharmaceutical Sciences, Chiba University, Inohana 1-8-1, Chuo-ku, Chiba 260-8675, Japan
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Pascual I, Berjón A, Lostao MP, Barber A. Transport of d-galactose by the gastrointestinal tract of the locust, Locusta migratoria. Comp Biochem Physiol B Biochem Mol Biol 2006; 143:20-6. [PMID: 16314134 DOI: 10.1016/j.cbpb.2005.09.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2005] [Revised: 09/02/2005] [Accepted: 09/05/2005] [Indexed: 11/24/2022]
Abstract
Due to exoskeleton, the absorption of nutrients in adult insects takes place across the gastrointestinal tract epithelium. In most physiological studies, sugar intestinal absorption has been described as a diffusional process and to date no sugar transporter has been cloned from the digestive tract of insects. In the present work, the existence of a saturable transport system for galactose in the gastric caeca of Locusta migratoria is clearly demonstrated. This transport shows a relatively high affinity for galactose (apparent K0.5=2-3 mM) and is inhibited by glucose, 2-deoxyglucose and with less potency by fructose and alpha-methyl-d-glucoside. The absence of sodium or the presence of phloridzin hardly affects galactose absorption, indicating that it is not mediated by a SGLT1-like transporter. The absence of K+, Cl-, Mg2+ and Ca2+ or changes in the pH do not modify galactose absorption either. Nevertheless, phloretin, cytochalasin B and theophylline (inhibitors of facilitative transporters) decrease sugar uptake around 50%. Xenopus laevis oocytes microinjected with poly A+ RNA isolated from gastric caeca show sodium-independent galactose uptake that is three times higher than in non-injected oocytes, further supporting the existence of a mRNA coding for at least one equilibrative sugar transporter in L. migratoria gastric caeca.
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Affiliation(s)
- I Pascual
- Departamento de Fisiología y Nutrición, University of Navarra, C/ Irunlarrea s.n., 31008 Pamplona, Spain
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Tsuzuki S, Murai N, Miyake Y, Inouye K, Hirayasu H, Iwanaga T, Fushiki T. Evidence for the occurrence of membrane-type serine protease 1/matriptase on the basolateral sides of enterocytes. Biochem J 2005; 388:679-87. [PMID: 15669920 PMCID: PMC1138976 DOI: 10.1042/bj20041639] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
MT-SP1 (membrane-type serine protease 1)/matriptase is an epithelial-derived integral membrane enzyme. The purpose of the present study was to examine whether the enzyme exists on the basolateral side of simple columnar epithelial cells, such as enterocytes, of normal adult animals. Using COS-1 monkey kidney cells transiently transfected with rat MT-SP1/matriptase expression plasmids, we found that the enzyme is post-translationally processed by the cleavage between Gly149 and Ser150, that a portion of the C-terminal part (Ser150-Val855) remains in the cells by association with the NTF (N-terminal fragment) (Met1-Gly149), while the other portions are released into the medium and that the release is increased on activation by co-expression with hepatocyte growth factor activator inhibitor type-1. Western-blot analysis of crude membranes prepared from rat jejunum demonstrated the presence of the NTF but negligible or no occurrence of the C-terminal part of the protein. Fractionation of the crude membranes by ultracentrifugation with Percoll followed by Western-blot analysis showed that the fractionation profile of the NTF correlated significantly with that of E-cadherin, an adhesion molecule on the lateral membrane. Immunostaining of the jejunum demonstrated the occurrence of the NTF on the lateral membranes but not on the apical membranes. These results suggest that considerable MT-SP1/matriptase molecules occur on the basolateral sides of normal epithelial cells and support our hypothesis that a possible physiological function of this enzyme is the control of epithelial-cell turnover by regulating cell-cell and/or cell-substratum adhesions.
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Affiliation(s)
- Satoshi Tsuzuki
- Laboratory of Nutrition Chemistry, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan.
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40
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Gaudreault N, Scriven DRL, Moore EDW. Characterisation of glucose transporters in the intact coronary artery endothelium in rats: GLUT-2 upregulated by long-term hyperglycaemia. Diabetologia 2004; 47:2081-92. [PMID: 15662550 DOI: 10.1007/s00125-004-1583-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2004] [Accepted: 07/18/2004] [Indexed: 01/22/2023]
Abstract
AIMS/HYPOTHESIS We have examined the effects of streptozotocin-induced type 1 diabetes on the expression and subcellular distribution of the classic sugar transporters (GLUT-1 to 5 and sodium-dependent glucose transporter-1 [SGLT-1]) in the endothelial cells of an en face preparation of septal coronary artery from Wistar rats. METHODS The presence of the GLUT isoforms and SGLT-1 in the endothelial cell layer was determined by immunohistochemistry using wide-field fluorescence microscopy coupled to deconvolution, and was quantified by digital image analysis. RESULTS We found that all of the transporters were expressed within these cells and that all except SGLT-1 were preferentially located on the abluminal side. The heaviest labelling was adjacent to the cell-to-cell junctions where the luminal and abluminal membranes are in close proximity, which may reflect a spatial organisation specialised for vectorial glucose transport across the thinnest part of the cytoplasm. Long-term hyperglycaemia, induced by streptozotocin, significantly downregulated GLUT-1, 3, 4 and 5 and dramatically upregulated GLUT-2, leaving SGLT-1 unchanged. CONCLUSIONS/INTERPRETATION We conclude that the high susceptibility of endothelial cells to glucose toxicity may be the result of the subcellular organisation of their GLUTs and the increased expression of GLUT-2.
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Affiliation(s)
- N Gaudreault
- Department of Physiology, University of British Columbia, 2146 Health Sciences Mall, Vancouver, B.C., V6T 1Z3, Canada
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Uldry M, Thorens B. The SLC2 family of facilitated hexose and polyol transporters. Pflugers Arch 2004; 447:480-9. [PMID: 12750891 DOI: 10.1007/s00424-003-1085-0] [Citation(s) in RCA: 336] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2003] [Accepted: 04/04/2003] [Indexed: 12/18/2022]
Abstract
The SLC2 family of glucose and polyol transporters comprises 13 members, the glucose transporters (GLUT) 1-12 and the H(+)- myo-inositol cotransporter (HMIT). These proteins all contain 12 transmembrane domains with both the amino and carboxy-terminal ends located on the cytoplasmic side of the plasma membrane and a N-linked oligosaccharide side-chain located either on the first or fifth extracellular loop. Based on sequence comparison, the GLUT isoforms can be grouped into three classes: class I comprises GLUT1-4; class II, GLUT6, 8, 10, and 12 and class III, GLUT5, 7, 9, 11 and HMIT. Despite their sequence similarity and the presence of class-specific signature sequences, these transporters carry various hexoses and HMIT is a H(+)/ myo-inositol co-transporter. Furthermore, the substrate transported by some isoforms has not yet been identified. Tissue- and cell-specific expression of the well-characterized GLUT isoforms underlies their specific role in the control of whole-body glucose homeostasis. Numerous studies with transgenic or knockout mice indeed support an important role for these transporters in the control of glucose utilization, glucose storage and glucose sensing. Much remains to be learned about the transport functions of the recently discovered isoforms (GLUT6-13 and HMIT) and their physiological role in the metabolism of glucose, myo-inositol and perhaps other substrates.
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Affiliation(s)
- Marc Uldry
- Institute of Pharmacology and Toxicology, University of Lausanne, 27, Rue du Bugnon, 1005, Lausanne, Switzerland
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Giordana B, Milani A, Grimaldi A, Farneti R, Casartelli M, Ambrosecchio MR, Digilio MC, Leonardi MG, de Eguileor M, Pennacchio F. Absorption of sugars and amino acids by the epidermis of Aphidius ervi larvae. JOURNAL OF INSECT PHYSIOLOGY 2003; 49:1115-1124. [PMID: 14624883 DOI: 10.1016/j.jinsphys.2003.08.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Aphidius ervi Haliday (Hymenoptera, Braconidae) is an endophagous parasitoid of several aphid species of economic importance, widely used in biological control. The definition of a suitable artificial diet for in vitro mass production of this parasitoid is still an unresolved issue that, to be properly addressed, requires a deeper understanding both of its nutritional needs and of the functional properties of the larval epithelia involved in nutrient absorption. The experimental evidence presented in this paper unequivocally demonstrates that the uptake of sugars and amino acids takes place through the body surface of the larval stages of A. ervi. These nutrients are efficiently absorbed by the larval epidermis, but the transport rate progressively declines over time. The epidermis exhibits a cross-reactivity to antibodies raised against the mammalian facilitative glucose transporter GLUT2 and the sodium cotransporter SGLT1. The analysis of sugar transport sensitivity to specific inhibitors indicates the involvement of GLUT2-like transporters, while a role for SGLT1-like transporters is not supported. The peculiar pathways of nutrient absorption in A. ervi larvae further corroborate the general idea that the pre-imaginal stages of endophagous koinobiont Hymenoptera, like Metazoan parasites, show a high degree of physiological integration with their hosts.
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Affiliation(s)
- B Giordana
- Dipartimento di Biologia, Università di Milano, via Celoria 26, 20133 Milan, Italy
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Abstract
Carbohydrates are mostly digested to glucose, fructose and galactose before absorption by the small intestine. Absorption across the brush border and basolateral membranes of enterocytes is mediated by sodium-dependent and -independent membrane proteins. Glucose and galactose transport across the brush border occurs by a Na(+)/glucose (galactose) co-transporter (SGLT1), whereas passive fructose transport is mediated by a uniporter (GLUT5). The passive exit of all three sugars out of the cell across the basolateral membrane occurs through two uniporters (GLUT2 and GLUT5). Mutations in SGLT1 cause a major defect in glucose and galactose absorption (glucose-galactose Malabsorption), but mutations in GLUT2 do not appear to disrupt glucose and galactose absorption. Studies on GLUT1 null mice and Fanconi-Bickel patients suggest that there is another exit pathway for glucose and galactose that may involve exocytosis. There are no known defects of fructose absorption.
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Affiliation(s)
- Ernest M Wright
- Departments of Physiology and Pediatrics, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-1751, USA.
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44
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Gouyon F, Caillaud L, Carriere V, Klein C, Dalet V, Citadelle D, Kellett GL, Thorens B, Leturque A, Brot-Laroche E. Simple-sugar meals target GLUT2 at enterocyte apical membranes to improve sugar absorption: a study in GLUT2-null mice. J Physiol 2003; 552:823-32. [PMID: 12937289 PMCID: PMC2343460 DOI: 10.1113/jphysiol.2003.049247] [Citation(s) in RCA: 135] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The physiological significance of the presence of GLUT2 at the food-facing pole of intestinal cells is addressed by a study of fructose absorption in GLUT2-null and control mice submitted to different sugar diets. Confocal microscopy localization, protein and mRNA abundance, as well as tissue and membrane vesicle uptakes of fructose were assayed. GLUT2 was located in the basolateral membrane of mice fed a meal devoid of sugar or containing complex carbohydrates. In addition, the ingestion of a simple sugar meal promoted the massive recruitment of GLUT2 to the food-facing membrane. Fructose uptake in brush-border membrane vesicles from GLUT2-null mice was half that of wild-type mice and was similar to the cytochalasin B-insensitive component, i.e. GLUT5-mediated uptake. A 5 day consumption of sugar-rich diets increased fructose uptake fivefold in wild-type tissue rings when it only doubled in GLUT2-null tissue. GLUT5 was estimated to contribute to 100 % of total uptake in wild-type mice fed low-sugar diets, falling to 60 and 40 % with glucose and fructose diets respectively; the complement was ensured by GLUT2 activity. The results indicate that basal sugar uptake is mediated by the resident food-facing SGLT1 and GLUT5 transporters, whose mRNA abundances double in long-term dietary adaptation. We also observe that a large improvement of intestinal absorption is promoted by the transient recruitment of food-facing GLUT2, induced by the ingestion of a simple-sugar meal. Thus, GLUT2 and GLUT5 could exert complementary roles in adapting the absorption capacity of the intestine to occasional or repeated loads of dietary sugars.
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Affiliation(s)
- F Gouyon
- INSERM U505, UPMC, Paris, France
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45
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Yang J, Dowden J, Tatibouët A, Hatanaka Y, Holman GD. Development of high-affinity ligands and photoaffinity labels for the D-fructose transporter GLUT5. Biochem J 2002; 367:533-9. [PMID: 12119043 PMCID: PMC1222899 DOI: 10.1042/bj20020843] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2002] [Revised: 07/02/2002] [Accepted: 07/16/2002] [Indexed: 01/25/2023]
Abstract
The GLUT5 transporter catalyses the specific uptake of D-fructose and can accept this hexose in its furanose and pyranose ring forms. The transporter does not accept fructose epimers and has very limited tolerance of bulky groups substituted at the 2-, 3-, 4- and 5-OH positions [Tatibouët, Yang, Morin and Holman (2000) Bioorg. Med. Chem. 8, 1825-1833]. To further explore whether bulky groups can be tolerated at the primary OH positions, a D-fructose analogue with an allylamine group substitution to replace the 1-OH group was synthesized and was found to be quite well tolerated ( K (i)=27.1 mM). However, this analogue occurs in multiple ring forms. By contrast, 2,5-anhydro-D-mannitol is a symmetrical molecule that occurs only in a furanose ring form in which C-1 and C-6 are equivalent. We have therefore synthesized new 2,5-anhydro-D-mannitol analogues (substituted at the equivalent of the 6-OH of D-fructose) and from studies in Chinese hamster ovary cells expressing GLUT5 cells report that (i) the allylamine derivative of 2,5-anhydro-D-mannitol is well tolerated ( K (i)=2.66 mM); (ii) introduction of a di-nitrophenyl-substituted secondary amine group enhances affinity ( K (i)=0.56 mM); (iii) introduction of amide-linked biotinylated photolabel moieties is possible without loss of affinity relative to 2,5-anhydro-D-mannitol but a small secondary amine spacer between the biotinylated photolabelling moiety and the fructofuranose ring increases affinity (fructose photolabel 2; K (i)=1.16 mM); (iv) introduction of a hydrophilic tartarate spacer between biotin and the diazirine photoreactive groups can be accomplished without reduction in affinity and (v) photoactivation of biotinylated fructose photolabels leads to specific biotin tagging of GLUT5. These data suggest that substitution of a secondary amine group (-NH) to replace the C-6 (or C-1) -OH of 2,5-anhydro-D-mannitol results in compounds of high affinity; the affinity is enhanced over 10-fold compared with D-fructose.
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Affiliation(s)
- Jing Yang
- Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K
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46
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Abstract
The Na(+)-dependent glucose transporter SGLT1 and the facilitated fructose transporter GLUT5 absorb sugars from the intestinal lumen across the brush-border membrane into the cells. The activity of these transport systems is known to be regulated primarily by diet and development. The cloning of these transporters has led to a surge of studies on cellular mechanisms regulating intestinal sugar transport. However, the small intestine can be a difficult organ to study, because its cells are continuously differentiating along the villus, and because the function of absorptive cells depends on both their state of maturity and their location along the villus axis. In this review, I describe the typical patterns of regulation of transport activity by dietary carbohydrate, Na(+) and fibre, how these patterns are influenced by circadian rhythms, and how they vary in different species and during development. I then describe the molecular mechanisms underlying these regulatory patterns. The expression of these transporters is tightly linked to the villus architecture; hence, I also review the regulatory processes occurring along the crypt-villus axis. Regulation of glucose transport by diet may involve increased transcription of SGLT1 mainly in crypt cells. As cells migrate to the villus, the mRNA is degraded, and transporter proteins are then inserted into the membrane, leading to increases in glucose transport about a day after an increase in carbohydrate levels. In the SGLT1 model, transport activity in villus cells cannot be modulated by diet. In contrast, GLUT5 regulation by the diet seems to involve de novo synthesis of GLUT5 mRNA synthesis and protein in cells lining the villus, leading to increases in fructose transport a few hours after consumption of diets containing fructose. In the GLUT5 model, transport activity can be reprogrammed in mature enterocytes lining the villus column. Innovative experimental approaches are needed to increase our understanding of sugar transport regulation in the small intestine. I close by suggesting specific areas of research that may yield important information about this interesting, but difficult, topic.
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Abstract
The Na(+)-dependent glucose transporter SGLT1 and the facilitated fructose transporter GLUT5 absorb sugars from the intestinal lumen across the brush-border membrane into the cells. The activity of these transport systems is known to be regulated primarily by diet and development. The cloning of these transporters has led to a surge of studies on cellular mechanisms regulating intestinal sugar transport. However, the small intestine can be a difficult organ to study, because its cells are continuously differentiating along the villus, and because the function of absorptive cells depends on both their state of maturity and their location along the villus axis. In this review, I describe the typical patterns of regulation of transport activity by dietary carbohydrate, Na(+) and fibre, how these patterns are influenced by circadian rhythms, and how they vary in different species and during development. I then describe the molecular mechanisms underlying these regulatory patterns. The expression of these transporters is tightly linked to the villus architecture; hence, I also review the regulatory processes occurring along the crypt-villus axis. Regulation of glucose transport by diet may involve increased transcription of SGLT1 mainly in crypt cells. As cells migrate to the villus, the mRNA is degraded, and transporter proteins are then inserted into the membrane, leading to increases in glucose transport about a day after an increase in carbohydrate levels. In the SGLT1 model, transport activity in villus cells cannot be modulated by diet. In contrast, GLUT5 regulation by the diet seems to involve de novo synthesis of GLUT5 mRNA synthesis and protein in cells lining the villus, leading to increases in fructose transport a few hours after consumption of diets containing fructose. In the GLUT5 model, transport activity can be reprogrammed in mature enterocytes lining the villus column. Innovative experimental approaches are needed to increase our understanding of sugar transport regulation in the small intestine. I close by suggesting specific areas of research that may yield important information about this interesting, but difficult, topic.
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Affiliation(s)
- R P Ferraris
- Department of Pharmacology and Physiology, UMDNJ-New Jersey Medical School, 185 S. Orange Avenue, Newark, NJ 07103-2714, USA.
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Stümpel F, Burcelin R, Jungermann K, Thorens B. Normal kinetics of intestinal glucose absorption in the absence of GLUT2: evidence for a transport pathway requiring glucose phosphorylation and transfer into the endoplasmic reticulum. Proc Natl Acad Sci U S A 2001; 98:11330-5. [PMID: 11562503 PMCID: PMC58729 DOI: 10.1073/pnas.211357698] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Glucose is absorbed through the intestine by a transepithelial transport system initiated at the apical membrane by the cotransporter SGLT-1; intracellular glucose is then assumed to diffuse across the basolateral membrane through GLUT2. Here, we evaluated the impact of GLUT2 gene inactivation on this transepithelial transport process. We report that the kinetics of transepithelial glucose transport, as assessed in oral glucose tolerance tests, was identical in the presence or absence of GLUT2; that the transport was transcellular because it could be inhibited by the SGLT-1 inhibitor phlorizin, and that it could not be explained by overexpression of another known glucose transporter. By using an isolated intestine perfusion system, we demonstrated that the rate of transepithelial transport was similar in control and GLUT2(-/-) intestine and that it was increased to the same extent by cAMP in both situations. However, in the absence, but not in the presence, of GLUT2, the transport was inhibited dose-dependently by the glucose-6-phosphate translocase inhibitor S4048. Furthermore, whereas transport of [(14)C]glucose proceeded with the same kinetics in control and GLUT2(-/-) intestine, [(14)C]3-O-methylglucose was transported in intestine of control but not of mutant mice. Together our data demonstrate the existence of a transepithelial glucose transport system in GLUT2(-/-) intestine that requires glucose phosphorylation and transfer of glucose-6-phosphate into the endoplasmic reticulum. Glucose may then be released out of the cells by a membrane traffic-based pathway similar to the one we previously described in GLUT2-null hepatocytes.
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Affiliation(s)
- F Stümpel
- Georg-August-University Göttingen, Institute for Biochemistry and Molecular Cell Biology, Humboldtallee 23, 37073 Göttingen, Germany
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49
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Cornford EM, Cornford ME, Wright EM, Bruckner DA, Sampogna S, Hirayama BA. Human cerebral cysticercosis: immunolocalization of a sodium-dependent glucose cotransporter (SGLT) in larval and adult tapeworms. J Parasitol 2001; 87:510-21. [PMID: 11426712 DOI: 10.1645/0022-3395(2001)087[0510:hccioa]2.0.co;2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Light microscopic immunocytochemistry was used to examine human brain cysticerci resected from the fourth ventricles of patients who had not been treated with anthelminthic drugs. Tissues were examined from 3 different patients undergoing surgery for treatment of hydrocephalus. A rabbit polyclonal antiserum to the peptide corresponding to amino acids 564-575 unique to the rabbit sodium-dependent, SGLT1 glucose cotransporter labeled with immunoperoxidase, localized immunoreactive SGLT epitopes. This antibody localizes SGLT1 in the apical brush borders of human enterocytes, but is negative in cytoplasm, as well as lateral and basal enterocyte membranes. Taenia solium neurocysticerci were SGLT positive; transporter protein was highly expressed on the surface microvilli of the external cyst wall. The well-developed network of small and larger osmoregulatory ducts within racemose larval cystcerci displayed high expression of SGLT cotransporter, consistent with a resorptive function for this system of tubules. Because water is cotransported with glucose molecules by the SGLT protein, its high expression in neurocysticerci may contribute to the expansive growth of these larvae in subarachnoid and intraventricular sites. The SGLT epitopes were also immunolocalized in gravid proglottids of Taenia saginata, indicating that cotransporter expression persisted in intestinal-dwelling, adult tapeworms. Cotransporter antibody was abundantly localized at the proglottid tegumentary surface and in the lateral osmoregulatory ducts, analogous to the SGLT localization in cysticerci. Furthermore, high expression of this cotransporter was seen in the branches of the uterus, suggesting that SGLT-mediated absorption of glucose and water has an important functional role within the reproductive system of adult tapeworms.
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Affiliation(s)
- E M Cornford
- Department of Neurology, Brain Research Institute, UCLA School of Medicine, Los Angeles, California 90095, USA.
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Chapter 4 Genetic regulation of expression of intestinal biomembrane transport proteins in response to dietary protein, carbohydrate, and lipid. CURRENT TOPICS IN MEMBRANES 2000. [DOI: 10.1016/s1063-5823(00)50006-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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