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Fan M, Wu H, Sferruzzi-Perri AN, Wang YL, Shao X. Endocytosis at the maternal-fetal interface: balancing nutrient transport and pathogen defense. Front Immunol 2024; 15:1415794. [PMID: 38957469 PMCID: PMC11217186 DOI: 10.3389/fimmu.2024.1415794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Accepted: 06/03/2024] [Indexed: 07/04/2024] Open
Abstract
Endocytosis represents a category of regulated active transport mechanisms. These encompass clathrin-dependent and -independent mechanisms, as well as fluid phase micropinocytosis and macropinocytosis, each demonstrating varying degrees of specificity and capacity. Collectively, these mechanisms facilitate the internalization of cargo into cellular vesicles. Pregnancy is one such physiological state during which endocytosis may play critical roles. A successful pregnancy necessitates ongoing communication between maternal and fetal cells at the maternal-fetal interface to ensure immunologic tolerance for the semi-allogenic fetus whilst providing adequate protection against infection from pathogens, such as viruses and bacteria. It also requires transport of nutrients across the maternal-fetal interface, but restriction of potentially harmful chemicals and drugs to allow fetal development. In this context, trogocytosis, a specific form of endocytosis, plays a crucial role in immunological tolerance and infection prevention. Endocytosis is also thought to play a significant role in nutrient and toxin handling at the maternal-fetal interface, though its mechanisms remain less understood. A comprehensive understanding of endocytosis and its mechanisms not only enhances our knowledge of maternal-fetal interactions but is also essential for identifying the pathogenesis of pregnancy pathologies and providing new avenues for therapeutic intervention.
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Affiliation(s)
- Mingming Fan
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- Key Laboratory of Organ Regeneration and Reconstruction, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Hongyu Wu
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- Key Laboratory of Organ Regeneration and Reconstruction, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Amanda N. Sferruzzi-Perri
- Centre for Trophoblast Research, Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - Yan-Ling Wang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- Key Laboratory of Organ Regeneration and Reconstruction, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
- Beijing Institute for Stem Cell and Regenerative Medicine, Beijing, China
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, China
| | - Xuan Shao
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- Key Laboratory of Organ Regeneration and Reconstruction, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
- Beijing Institute for Stem Cell and Regenerative Medicine, Beijing, China
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, China
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2
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Sharma S, Ramachandran A, Sharma A. Role of riboflavin deficiency in malaria pathophysiology. PLoS Pathog 2024; 20:e1011991. [PMID: 38427625 PMCID: PMC10906831 DOI: 10.1371/journal.ppat.1011991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2024] Open
Abstract
The emergence of resistance against antimalarials and insecticides poses a significant threat to malaria elimination strategies. It is crucial to explore potential risk factors for malaria to identify new targets and alternative therapies. Malnutrition is a well-established risk factor for malaria. Deficiencies of micronutrients such as vitamin A, zinc, iron, folic acid, and phenotypic measures of malnutrition, such as stunting and wasting, have been studied extensively in the context of malaria. Vitamin B2, also known as riboflavin, is a micronutrient involved in maintaining cellular homeostasis. Riboflavin deficiency has been shown to have an inverse correlation with malarial parasitaemia. This article reviews the role of riboflavin in maintaining redox homeostasis and probes how riboflavin deficiency could alter malaria pathogenesis by disrupting the balance between oxidants and antioxidants. Though riboflavin analogues have been explored as antimalarials, new in vivo and patient-based research is required to target riboflavin-associated pathways for antimalarial therapy.
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Affiliation(s)
- Shweta Sharma
- ICMR–National Institute of Malaria Research, New Delhi, India
- ACSIR, Ghaziabad, Uttar Pradesh, India
| | - Arathy Ramachandran
- Molecular Medicine Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
| | - Amit Sharma
- Molecular Medicine Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
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3
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Ben Mariem O, Saporiti S, Guerrini U, Laurenzi T, Palazzolo L, Indiveri C, Barile M, De Fabiani E, Eberini I. In silico investigation on structure-function relationship of members belonging to the human SLC52 transporter family. Proteins 2022; 91:619-633. [PMID: 36511838 DOI: 10.1002/prot.26453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 11/18/2022] [Accepted: 12/08/2022] [Indexed: 12/15/2022]
Abstract
Riboflavin is an essential water-soluble vitamin that needs to be provided through the diet because of the conversion into flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN), important cofactors in hundreds of flavoenzymes. The adsorption and distribution of riboflavin is mediated by transmembrane transporters of the SLC52 family, namely RFVT1-3, whose mutations are mainly associated with two diseases, MADD and the Brown-Vialetto-Van Laere syndrome. Interest in RFVTs as pharmacological targets has increased in the last few years due to their overexpression in several cancer cells, which can be exploited both by blocking the uptake of riboflavin into the cancerous cells, and by performing cancer targeted delivery of drugs with a high affinity for RFVTs. In this work, we propose three-dimensional structural models for all three human riboflavin transporters obtained by state-of-the-art artificial intelligence-based methods, which were then further refined with molecular dynamics simulations. Furthermore, two of the most notable mutations concerning RFVT2 and RFVT3 (W31S and N21S, respectively) were investigated studying the interactions between the wild-type and mutated transporters with riboflavin.
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Affiliation(s)
- Omar Ben Mariem
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Via Giuseppe Balzaretti 9, Milan, Italy
| | - Simona Saporiti
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Via Giuseppe Balzaretti 9, Milan, Italy
| | - Uliano Guerrini
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Via Giuseppe Balzaretti 9, Milan, Italy
| | - Tommaso Laurenzi
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Via Giuseppe Balzaretti 9, Milan, Italy
| | - Luca Palazzolo
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Via Giuseppe Balzaretti 9, Milan, Italy
| | - Cesare Indiveri
- CNR Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies (IBIOM), Bari, Italy.,Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via P. Bucci cubo 4C, Arcavacata di Rende, Italy
| | - Maria Barile
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari A.Moro, Bari, Italy
| | - Emma De Fabiani
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Via Giuseppe Balzaretti 9, Milan, Italy
| | - Ivano Eberini
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Via Giuseppe Balzaretti 9, Milan, Italy.,DSRC, Università degli Studi di Milano, Milan, Italy
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4
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Yerevanian A, Murphy LM, Emans S, Zhou Y, Ahsan FM, Baker D, Li S, Adedoja A, Cedillo L, Stuhr NL, Gnanatheepam E, Dao K, Jain M, Curran SP, Georgakoudi I, Soukas AA. Riboflavin depletion promotes longevity and metabolic hormesis in Caenorhabditis elegans. Aging Cell 2022; 21:e13718. [PMID: 36181246 PMCID: PMC9649603 DOI: 10.1111/acel.13718] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 08/16/2022] [Accepted: 08/31/2022] [Indexed: 01/25/2023] Open
Abstract
Riboflavin is an essential cofactor in many enzymatic processes and in the production of flavin adenine dinucleotide (FAD). Here, we report that the partial depletion of riboflavin through knockdown of the C. elegans riboflavin transporter 1 (rft-1) promotes metabolic health by reducing intracellular flavin concentrations. Knockdown of rft-1 significantly increases lifespan in a manner dependent upon AMP-activated protein kinase (AMPK)/aak-2, the mitochondrial unfolded protein response, and FOXO/daf-16. Riboflavin depletion promotes altered energetic and redox states and increases adiposity, independent of lifespan genetic dependencies. Riboflavin-depleted animals also exhibit the activation of caloric restriction reporters without any reduction in caloric intake. Our findings indicate that riboflavin depletion activates an integrated hormetic response that promotes lifespan and healthspan in C. elegans.
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Affiliation(s)
- Armen Yerevanian
- Department of Medicine, Diabetes Unit and Center for Genomic MedicineMassachusetts General HospitalBostonMassachusettsUSA
- Department of MedicineHarvard Medical SchoolBostonMassachusettsUSA
| | - Luke M. Murphy
- Department of Medicine, Diabetes Unit and Center for Genomic MedicineMassachusetts General HospitalBostonMassachusettsUSA
- Department of MedicineHarvard Medical SchoolBostonMassachusettsUSA
| | - Sinclair Emans
- Department of Medicine, Diabetes Unit and Center for Genomic MedicineMassachusetts General HospitalBostonMassachusettsUSA
- Department of MedicineHarvard Medical SchoolBostonMassachusettsUSA
| | - Yifei Zhou
- Department of Medicine, Diabetes Unit and Center for Genomic MedicineMassachusetts General HospitalBostonMassachusettsUSA
- Department of MedicineHarvard Medical SchoolBostonMassachusettsUSA
| | - Fasih M. Ahsan
- Department of Medicine, Diabetes Unit and Center for Genomic MedicineMassachusetts General HospitalBostonMassachusettsUSA
- Department of MedicineHarvard Medical SchoolBostonMassachusettsUSA
| | - Daniel Baker
- Department of Medicine, Diabetes Unit and Center for Genomic MedicineMassachusetts General HospitalBostonMassachusettsUSA
- Department of MedicineHarvard Medical SchoolBostonMassachusettsUSA
| | - Sainan Li
- Department of Medicine, Diabetes Unit and Center for Genomic MedicineMassachusetts General HospitalBostonMassachusettsUSA
- Department of MedicineHarvard Medical SchoolBostonMassachusettsUSA
| | - Adebanjo Adedoja
- Department of Medicine, Diabetes Unit and Center for Genomic MedicineMassachusetts General HospitalBostonMassachusettsUSA
- Department of MedicineHarvard Medical SchoolBostonMassachusettsUSA
| | - Lucydalila Cedillo
- Department of Medicine, Diabetes Unit and Center for Genomic MedicineMassachusetts General HospitalBostonMassachusettsUSA
- Department of MedicineHarvard Medical SchoolBostonMassachusettsUSA
| | - Nicole L. Stuhr
- Leonard Davis School of GerontologyUniversity of Southern CaliforniaLos AngelesCaliforniaUSA
| | - Einstein Gnanatheepam
- Department of Biomedical EngineeringTufts University School of EngineeringMedfordMassachusettsUSA
| | - Khoi Dao
- Department of Medicine and PharmacologyUniversity of California San DiegoSan DiegoCaliforniaUSA
| | - Mohit Jain
- Department of Medicine and PharmacologyUniversity of California San DiegoSan DiegoCaliforniaUSA
| | - Sean P. Curran
- Leonard Davis School of GerontologyUniversity of Southern CaliforniaLos AngelesCaliforniaUSA
| | - Irene Georgakoudi
- Department of Biomedical EngineeringTufts University School of EngineeringMedfordMassachusettsUSA
| | - Alexander A. Soukas
- Department of Medicine, Diabetes Unit and Center for Genomic MedicineMassachusetts General HospitalBostonMassachusettsUSA
- Department of MedicineHarvard Medical SchoolBostonMassachusettsUSA
- Broad Institute of Harvard and MITCambridgeMassachusettsUSA
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5
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Azuma T, Pánek T, Tice AK, Kayama M, Kobayashi M, Miyashita H, Suzaki T, Yabuki A, Brown MW, Kamikawa R. An enigmatic stramenopile sheds light on early evolution in Ochrophyta plastid organellogenesis. Mol Biol Evol 2022; 39:6555011. [PMID: 35348760 PMCID: PMC9004409 DOI: 10.1093/molbev/msac065] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Ochrophyta is an algal group belonging to the Stramenopiles and comprises diverse lineages of algae which contribute significantly to the oceanic ecosystems as primary producers. However, early evolution of the plastid organelle in Ochrophyta is not fully understood. In this study, we provide a well-supported tree of the Stramenopiles inferred by the large-scale phylogenomic analysis that unveils the eukaryvorous (nonphotosynthetic) protist Actinophrys sol (Actinophryidae) is closely related to Ochrophyta. We used genomic and transcriptomic data generated from A. sol to detect molecular traits of its plastid and we found no evidence of plastid genome and plastid-mediated biosynthesis, consistent with previous ultrastructural studies that did not identify any plastids in Actinophryidae. Moreover, our phylogenetic analyses of particular biosynthetic pathways provide no evidence of a current and past plastid in A. sol. However, we found more than a dozen organellar aminoacyl-tRNA synthases (aaRSs) that are of algal origin. Close relationships between aaRS from A. sol and their ochrophyte homologs document gene transfer of algal genes that happened before the divergence of Actinophryidae and Ochrophyta lineages. We further showed experimentally that organellar aaRSs of A. sol are targeted exclusively to mitochondria, although organellar aaRSs in Ochrophyta are dually targeted to mitochondria and plastids. Together, our findings suggested that the last common ancestor of Actinophryidae and Ochrophyta had not yet completed the establishment of host–plastid partnership as seen in the current Ochrophyta species, but acquired at least certain nuclear-encoded genes for the plastid functions.
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Affiliation(s)
- Tomonori Azuma
- Graduate School of Human and Environmental Studies, Kyoto University, Yoshida nihonmatsu cho, Sakyo ku, Kyoto, Kyoto, Japan
| | - Tomáš Pánek
- Department of Zoology, Faculty of Science, Charles University, Prague, Czech Republic.,Department of Biological Sciences, Mississippi State University, Mississippi State, MS, USA
| | - Alexander K Tice
- Department of Biological Sciences, Mississippi State University, Mississippi State, MS, USA
| | - Motoki Kayama
- Graduate School of Human and Environmental Studies, Kyoto University, Yoshida nihonmatsu cho, Sakyo ku, Kyoto, Kyoto, Japan
| | | | - Hideaki Miyashita
- Graduate School of Human and Environmental Studies, Kyoto University, Yoshida nihonmatsu cho, Sakyo ku, Kyoto, Kyoto, Japan
| | | | - Akinori Yabuki
- Japan Agency for Marine-Earth Science and Technology, Japan
| | - Matthew W Brown
- Department of Biological Sciences, Mississippi State University, Mississippi State, MS, USA
| | - Ryoma Kamikawa
- Graduate School of Agriculture, Kyoto University, Kitashirakawa oiwake cho, Sakyo ku, Kyoto, Kyoto, Japan
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6
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Jin C, Yonezawa A. Recent advances in riboflavin transporter RFVT and its genetic disease. Pharmacol Ther 2021; 233:108023. [PMID: 34662687 DOI: 10.1016/j.pharmthera.2021.108023] [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: 08/30/2021] [Revised: 09/30/2021] [Accepted: 10/12/2021] [Indexed: 12/20/2022]
Abstract
Riboflavin (vitamin B2) is essential for cellular growth and function. It is enzymatically converted to flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), which participate in the metabolic oxidation-reduction reactions of carbohydrates, amino acids, and lipids. Human riboflavin transporters RFVT1, RFVT2, and RFVT3 have been identified and characterized since 2008. They are highly specific transporters of riboflavin. RFVT3 has functional characteristics different from those of RFVT1 and RFVT2. RFVT3 contributes to absorption in the small intestine, reabsorption in the kidney, and transport to the fetus in the placenta, while RFVT2 mediates the tissue distribution of riboflavin from the blood. Several mutations in the SLC52A2 gene encoding RFVT2 and the SLC52A3 gene encoding RFVT3 were found in patients with a rare neurological disorder known as Brown-Vialetto-Van Laere syndrome. These patients commonly present with bulbar palsy, hearing loss, muscle weakness, and respiratory symptoms in infancy or later in childhood. A decrease in plasma riboflavin levels has been observed in several cases. Recent studies on knockout mice and patient-derived cells have advanced the understanding of these mechanisms. Here, we summarize novel findings on RFVT1-3 and their genetic diseases and discuss their potential as therapeutic drugs.
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Affiliation(s)
- Congyun Jin
- Department of Clinical Pharmacology and Therapeutics, Kyoto University Hospital, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan; Graduate School of Pharmaceutical Sciences, Kyoto University, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Atsushi Yonezawa
- Department of Clinical Pharmacology and Therapeutics, Kyoto University Hospital, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan; Graduate School of Pharmaceutical Sciences, Kyoto University, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan.
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7
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Alteration of Flavin Cofactor Homeostasis in Human Neuromuscular Pathologies. Methods Mol Biol 2021; 2280:275-295. [PMID: 33751442 DOI: 10.1007/978-1-0716-1286-6_18] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The aim of this short review chapter is to provide a brief summary of the relevance of riboflavin (Rf or vitamin B2) and its derived cofactors flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) for human neuromuscular bioenergetics.Therefore, as a completion of this book we would like to summarize what kind of human pathologies could derive from genetic disturbances of Rf transport, flavin cofactor synthesis and delivery to nascent apoflavoproteins, as well as by alteration of vitamin recycling during protein turnover.
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8
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Cooke LDF, Tumbarello DA, Harvey NC, Sethi JK, Lewis RM, Cleal JK. Endocytosis in the placenta: An undervalued mediator of placental transfer. Placenta 2021; 113:67-73. [PMID: 33994009 DOI: 10.1016/j.placenta.2021.04.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Revised: 04/21/2021] [Accepted: 04/27/2021] [Indexed: 12/16/2022]
Abstract
Endocytosis is an essential mechanism for cellular uptake in many human tissues. A range of endocytic mechanisms occur including clathrin-dependent and -independent mechanisms. However, the role of endocytosis in the placenta and the spatial localisation of individual mechanisms is not well understood. The two principal cell layers that comprise the placental barrier to maternal-fetal transfer are the syncytiotrophoblast and fetal capillary endothelium. Endocytic uptake into the syncytiotrophoblast has been demonstrated for physiological maternal molecules such as transferrin-bound iron and low density lipoprotein (LDL) and may play an important role in the uptake of several other micronutrients, serum proteins, and therapeutics at both major placental cell barriers. These mechanisms may also mediate placental uptake of some viruses and nanoparticles. This review introduces the mechanisms of cargo-specific endocytosis and what is known about their localisation in the placenta, focussing predominantly on the syncytiotrophoblast. A fuller understanding of placental endocytosis is necessary to explain both fetal nutrition and the properties of the placental barrier. Characterising placental endocytic mechanisms and their regulation may allow us to identify their role in pregnancy pathologies and provide new avenues for therapeutic intervention.
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Affiliation(s)
- Laura D F Cooke
- The Institute of Developmental Sciences, University of Southampton, Southampton General Hospital, Southampton, SO16 6YD, UK.
| | - David A Tumbarello
- Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Highfield Campus, Life Sciences Building 85, Southampton, SO17 1BJ, UK
| | - Nicholas C Harvey
- MRC Lifecourse Epidemiology Unit, University of Southampton, Southampton General Hospital, Southampton, SO16 6YD, UK; NIHR Southampton Biomedical Research Centre, University of Southampton and University Hospital Southampton NHS Foundation Trust, Southampton, SO16 6YD, UK
| | - Jaswinder K Sethi
- The Institute of Developmental Sciences, University of Southampton, Southampton General Hospital, Southampton, SO16 6YD, UK; NIHR Southampton Biomedical Research Centre, University of Southampton and University Hospital Southampton NHS Foundation Trust, Southampton, SO16 6YD, UK; Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
| | - Rohan M Lewis
- The Institute of Developmental Sciences, University of Southampton, Southampton General Hospital, Southampton, SO16 6YD, UK; Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
| | - Jane K Cleal
- The Institute of Developmental Sciences, University of Southampton, Southampton General Hospital, Southampton, SO16 6YD, UK; Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
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9
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Tolomeo M, Nisco A, Leone P, Barile M. Development of Novel Experimental Models to Study Flavoproteome Alterations in Human Neuromuscular Diseases: The Effect of Rf Therapy. Int J Mol Sci 2020; 21:ijms21155310. [PMID: 32722651 PMCID: PMC7432027 DOI: 10.3390/ijms21155310] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 07/20/2020] [Accepted: 07/21/2020] [Indexed: 02/07/2023] Open
Abstract
Inborn errors of Riboflavin (Rf) transport and metabolism have been recently related to severe human neuromuscular disorders, as resulting in profound alteration of human flavoproteome and, therefore, of cellular bioenergetics. This explains why the interest in studying the “flavin world”, a topic which has not been intensively investigated before, has increased much over the last few years. This also prompts basic questions concerning how Rf transporters and FAD (flavin adenine dinucleotide) -forming enzymes work in humans, and how they can create a coordinated network ensuring the maintenance of intracellular flavoproteome. The concept of a coordinated cellular “flavin network”, introduced long ago studying humans suffering for Multiple Acyl-CoA Dehydrogenase Deficiency (MADD), has been, later on, addressed in model organisms and more recently in cell models. In the frame of the underlying relevance of a correct supply of Rf in humans and of a better understanding of the molecular rationale of Rf therapy in patients, this review wants to deal with theories and existing experimental models in the aim to potentiate possible therapeutic interventions in Rf-related neuromuscular diseases.
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10
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Glycolate is a Novel Marker of Vitamin B 2 Deficiency Involved in Gut Microbe Metabolism in Mice. Nutrients 2020; 12:nu12030736. [PMID: 32168816 PMCID: PMC7146322 DOI: 10.3390/nu12030736] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 03/07/2020] [Accepted: 03/08/2020] [Indexed: 12/22/2022] Open
Abstract
Microbes in the human gut play a role in the production of bioactive compounds, including some vitamins. Although several studies attempted to identify definitive markers for certain vitamin deficiencies, the role of gut microbiota in these deficiencies is unclear. To investigate the role of gut microbiota in deficiencies of four vitamins, B2, B6, folate, and B12, we conducted a comprehensive analysis of metabolites in mice treated and untreated with antibiotics. We identified glycolate (GA) as a novel marker of vitamin B2 (VB2) deficiency, and show that gut microbiota sense dietary VB2 deficiency and accumulate GA in response. The plasma GA concentration responded to reduced VB2 supply from both the gut microbiota and the diet. These results suggest that GA is a novel marker that can be used to assess whether or not the net supply of VB2 from dietary sources and gut microbiota is sufficient. We also found that gut microbiota can provide short-term compensation for host VB2 deficiency when dietary VB2 is withheld.
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11
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Riboflavin transport mediated by riboflavin transporters (RFVTs/SLC52A) at the rat outer blood-retinal barrier. Drug Metab Pharmacokinet 2019; 34:380-386. [PMID: 31601465 DOI: 10.1016/j.dmpk.2019.08.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 08/01/2019] [Accepted: 08/09/2019] [Indexed: 12/31/2022]
Abstract
The previous in vivo study revealed the carrier-mediated transport of riboflavin (vitamin B2) across the blood-retinal barrier (BRB). In the present study, the blood-to-retina supply of riboflavin across the outer BRB was assessed in RPE-J cells, a rat-derived in vitro cell model of the outer BRB that is formed by the retinal pigment epithelial cells. In the directional uptake analysis on collagen-coated Transwell® inserts, RPE-J cells showed higher basal-to-cell (B-to-C) uptake (22.8 μL/mg protein) of [3H]riboflavin than apical-to-cell (A-to-C) uptake (13.5 μL/mg protein). RPE-J cells showed concentration- and temperature-dependent uptake of [3H]riboflavin with a Km of 297 nM, suggesting the involvement of carrier-mediated process in the blood-to-retina transport of riboflavin across the outer BRB. In RPE-J cells, [3H]riboflavin uptake was affected under a K+-replacement condition while no effect was observed under a choline-replacement condition and at different pH values. Uptake of [3H]riboflavin by RPE-J cells was markedly reduced by riboflavin, flavin adenine dinucleotide (FAD), and lumichrome with no significant effect noted for other vitamins. The obtained results suggested the involvement of riboflavin transporters (SLC52A/RFVT) at the outer BRB, and this is supported by the expression and knockdown analyses of rRFVT2 (Slc52a2) and rRFVT3 (Slc52a3).
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12
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Yang R, Wei Z, Wu S. Lumiflavin increases the sensitivity of ovarian cancer stem-like cells to cisplatin by interfering with riboflavin. J Cell Mol Med 2019; 23:5329-5339. [PMID: 31187586 PMCID: PMC6652702 DOI: 10.1111/jcmm.14409] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Revised: 05/05/2019] [Accepted: 05/09/2019] [Indexed: 12/11/2022] Open
Abstract
Here, we used lumiflavin, an inhibitor of riboflavin, as a new potential therapeutic chemosensitizer to ovarian cancer stem‐like cells (CSCs). This study demonstrates that the enrichment of riboflavin in CSCs is an important cause of its resistance to chemotherapy. Lumiflavin can effectively reduce the riboflavin enrichment in CSCs and sensitize the effect of cisplatin Diamminedichloroplatinum (DDP) on CSCs. In this study, CSCs of human ovarian cancer cell lines HO8910 were separated using a magnetic bead (CD133+). We also show the overexpression of the mRNA and protein of riboflavin transporter 2 and the high content of riboflavin in CSCs compared to non‐CSCs (NON‐CSCs). Moreover, CSCs were less sensitive to DDP than NON‐CSCs, whereas, the synergistic effect of lumiflavin and DDP on CSCs was more sensitive than NON‐CSCs. Further research showed that lumiflavin had synergistic effects with DDP on CSCs in increasing mitochondrial function damage and apoptosis rates and decreasing clonic function. In addition, we found that the combination of DDP and lumiflavin therapy in vivo has a synergistic cytotoxic effect on an ovarian cancer nude mice model by enhancing the DNA‐damage response and increasing the apoptotic protein expression. Notably, the effect of lumiflavin is associated with reduced riboflavin concentration, and riboflavin could reverse the effect of DDP in vitro and in vivo. Accordingly, we conclude that lumiflavin interfered with the riboflavin metabolic pathways, resulting in a significant increase in tumour sensitivity to DDP therapy. Our study suggests that lumiflavin may be a novel treatment alternative for ovarian cancer and its recurrence.
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Affiliation(s)
- Ruhui Yang
- Department of Pharmacology, College of Medicine and Health, Lishui University, Lishui, China
| | - Zhe Wei
- Department of Rehabilitation Medicine, College of Medicine and Health, Lishui University, Lishui, China
| | - Songquan Wu
- Department of Immunology, College of Medicine and Health, Lishui University, Lishui, China
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13
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Sabui S, Subramanian VS, Pham Q, Said HM. Identification of transmembrane protein 237 as a novel interactor with the intestinal riboflavin transporter-3 (RFVT-3): role in functionality and cell biology. Am J Physiol Cell Physiol 2019; 316:C805-C814. [PMID: 30892938 DOI: 10.1152/ajpcell.00029.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The apically localized riboflavin (RF) transporter-3 (RFVT-3) is involved in intestinal absorption of vitamin B2. Previous studies have characterized different physiological/biological aspects of the RFVT-3, but there is a lack of knowledge regarding possible existence of interacting partner(s) and consequence of interaction(s) on its function/cell biology. To address the latter, we performed yeast two-hybrid (Y2H) screening of a human colonic cDNA library and have identified transmembrane protein 237 (TMEM237) as a putative interactor with the human (h)RFVT-3; the interaction was further confirmed via "1-by-1" Y2H assay that involved appropriate positive and negative controls. TMEM237 was found to be highly expressed in human native intestine and in human intestinal epithelial cell lines; further, confocal images showed colocalization of the protein with hRFVT-3. The interaction between TMEM237 with hRFVT-3 in human intestinal epithelial HuTu-80 cells was established by coimmunoprecipitation. Expressing TMEM237 in HuTu-80 cells led to a significant induction in RF uptake, while its knockdown (with the use of gene-specific siRNA) led to a significant reduction in uptake. Transfecting TMEM237 into HuTu-80 cells also led to a marked enhancement in hRFVT-3 protein stability (reflected by an increase in the protein half-life). Interestingly, the level of expression of TMEM237 was found to be markedly reduced following treatment with TNF-α (a proinflammatory cytokine that inhibits intestinal RF uptake), while its expression was significantly upregulated following treatment with butyrate (an inducer of intestinal RF uptake). These findings identify TMEM237 as an interactor with the intestinal hRFVT-3 and show that the interaction has physiological/biological significance.
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Affiliation(s)
- Subrata Sabui
- Department of Physiology and Biophysics, School of Medicine, University of California , Irvine, California.,Department of Medicine, School of Medicine, University of California , Irvine, California.,Veterans Affairs Medical Center, Long Beach, California
| | - Veedamali S Subramanian
- Department of Physiology and Biophysics, School of Medicine, University of California , Irvine, California.,Department of Medicine, School of Medicine, University of California , Irvine, California.,Veterans Affairs Medical Center, Long Beach, California
| | - Quang Pham
- Department of Physiology and Biophysics, School of Medicine, University of California , Irvine, California
| | - Hamid M Said
- Department of Physiology and Biophysics, School of Medicine, University of California , Irvine, California.,Department of Medicine, School of Medicine, University of California , Irvine, California.,Veterans Affairs Medical Center, Long Beach, California
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Sodium Butyrate Enhances Intestinal Riboflavin Uptake via Induction of Expression of Riboflavin Transporter-3 (RFVT3). Dig Dis Sci 2019; 64:84-92. [PMID: 30276569 PMCID: PMC6320279 DOI: 10.1007/s10620-018-5305-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 09/24/2018] [Indexed: 02/06/2023]
Abstract
BACKGROUND Uptake of riboflavin (RF) by intestinal epithelial cells occurs via a specific carrier-mediated process that involves the apically localized RF transporter-3 (RFVT3). Previous studies have shown that sodium butyrate (NaB) affects intestinal uptake of other substrates and expression of their membrane transporters, but its effect on intestinal uptake of RF and expression of RFVT3 has not been examined. AIMS To investigate the effect of NaB on intestinal RF uptake process and expression of the RFVT3. METHODS Two experimental models were used in this study: Human-derived intestinal epithelial Caco-2 cells and ex vivo mouse colonoids. 3H-RF uptake assay, Western blot, RT-qPCR, and chromatin immunoprecipitation assay were performed. RESULTS Treating Caco-2 cells with NaB led to a significant increase in carrier-mediated RF uptake. This increase was associated with a significant induction in the level of expression of the hRFVT3 protein, mRNA, and heterogenous nuclear RNA (hnRNA). Similarly, treating mouse colonoids with NaB led to a marked increase in the level of expression of the mRFVT3 protein, mRNA, and hnRNA. NaB did not affect hRFVT3 mRNA stability, rather it caused significant epigenetic changes (histone modifications) in the SLC52A3 gene where an increase in H3Ac and a reduction in H3K27me3 levels were observed in the NaB-treated Caco-2 cells compared to untreated controls. CONCLUSION These findings demonstrate that NaB up-regulates intestinal RF uptake and that the effect appears to be mediated, at least in part, at the level of transcription of the SLC52A3 gene and may involve epigenetic mechanism(s).
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Abstract
Nine compounds are classified as water-soluble vitamins, eight B vitamins and one vitamin C. The vitamins are mandatory for the function of numerous enzymes and lack of one or more of the vitamins may lead to severe medical conditions. All the vitamins are supplied by food in microgram to milligram quantities and in addition some of the vitamins are synthesized by the intestinal microbiota. In the gastrointestinal tract, the vitamins are liberated from binding proteins and for some of the vitamins modified prior to absorption. Due to their solubility in water, they all require specific carriers to be absorbed. Our current knowledge concerning each of the vitamins differs in depth and focus and is influenced by the prevalence of conditions and diseases related to lack of the individual vitamin. Because of that we have chosen to cover slightly different aspects for the individual vitamins. For each of the vitamins, we summarize the physiological role, the steps involved in the absorption, and the factors influencing the absorption. In addition, for some of the vitamins, the molecular base for absorption is described in details, while for others new aspects of relevance for human deficiency are included. © 2018 American Physiological Society. Compr Physiol 8:1291-1311, 2018.
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Affiliation(s)
- Hamid M Said
- University of California-School of Medicine, Irvine, California, USA.,VA Medical Center, Long Beach, California, USA
| | - Ebba Nexo
- Department of Clinical Medicine, Clinical Biochemistry, Aarhus University Hospital, Aarhus, Denmark
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16
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Anandam KY, Alwan OA, Subramanian VS, Srinivasan P, Kapadia R, Said HM. Effect of the proinflammatory cytokine TNF-α on intestinal riboflavin uptake: inhibition mediated via transcriptional mechanism(s). Am J Physiol Cell Physiol 2018; 315:C653-C663. [PMID: 30156861 DOI: 10.1152/ajpcell.00295.2018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Riboflavin (RF), is essential for normal cellular metabolism/function. Intestinal RF absorption occurs via a specific carrier-mediated process that involves the apical transporter RFVT-3 ( SLC52A3) and the basolateral RFVT-1 (SLC52A1). Previously, we characterized different cellular/molecular aspects of the intestinal RF uptake process, but nothing is known about the effect of proinflammatory cytokines on the uptake event. We addressed this issue using in vitro, ex vivo, and in vivo models. First, we determined the level of mRNA expression of the human (h)RFVT-3 and hRFVT-1 in intestinal tissue of patients with inflammatory bowel disease (IBD) and observed a markedly lower level compared with controls. In the in vitro model, exposing Caco-2 cells to tumor necrosis factor-α (TNF-α) led to a significant inhibition in RF uptake, an effect that was abrogated upon knocking down TNF receptor 1 (TNFR1). The inhibition in RF uptake was associated with a significant reduction in the expression of hRFVT-3 and -1 protein and mRNA levels, as well as in the activity of the SLC52A3 and SLC52A1 promoters. The latter effects appear to involve Sp1 and NF-κB sites in these promoters. Similarly, exposure of mouse small intestinal enteroids and wild-type mice to TNF-α led to a significant inhibition in physiological and molecular parameters of intestinal RF uptake. Collectively, these findings demonstrate that exposure of intestinal epithelial cells to TNF-α leads to inhibition in RF uptake and that this effect is mediated, at least in part, via transcriptional mechanism(s). These findings may explain the significantly low RF levels observed in patients with IBD.
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Affiliation(s)
- Kasin Yadunandam Anandam
- Department of Medicine, University of California , Irvine, California.,Department of Physiology/Biophysics, University of California , Irvine, California.,Department of Medical Research, Veterans Affairs Medical Center , Long Beach, California
| | - Omar A Alwan
- Department of Medicine, University of California , Irvine, California.,Department of Physiology/Biophysics, University of California , Irvine, California.,Department of Medical Research, Veterans Affairs Medical Center , Long Beach, California
| | - Veedamali S Subramanian
- Department of Medicine, University of California , Irvine, California.,Department of Physiology/Biophysics, University of California , Irvine, California.,Department of Medical Research, Veterans Affairs Medical Center , Long Beach, California
| | - Padmanabhan Srinivasan
- Department of Medicine, University of California , Irvine, California.,Department of Physiology/Biophysics, University of California , Irvine, California.,Department of Medical Research, Veterans Affairs Medical Center , Long Beach, California
| | - Rubina Kapadia
- Department of Medicine, University of California , Irvine, California.,Department of Physiology/Biophysics, University of California , Irvine, California.,Department of Medical Research, Veterans Affairs Medical Center , Long Beach, California
| | - Hamid M Said
- Department of Medicine, University of California , Irvine, California.,Department of Physiology/Biophysics, University of California , Irvine, California.,Department of Medical Research, Veterans Affairs Medical Center , Long Beach, California
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17
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Thakur K, Tomar SK, Singh AK, Mandal S, Arora S. Riboflavin and health: A review of recent human research. Crit Rev Food Sci Nutr 2018; 57:3650-3660. [PMID: 27029320 DOI: 10.1080/10408398.2016.1145104] [Citation(s) in RCA: 159] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
There has lately been a renewed interest in Riboflavin owing to insight into its recognition as an essential component of cellular biochemistry. The knowledge of the mechanisms and regulation of intestinal absorption of riboflavin and its health implications has significantly been expanded in recent years. The purpose of this review is to provide an overview of the importance of riboflavin, its absorption and metabolism in health and diseased conditions, its deficiency and its association with various health diseases, and metabolic disorders. Efforts have been made to review the available information in literature on the relationship between riboflavin and various clinical abnormalities. The role of riboflavin has also been dealt in the prevention of a wide array of health diseases like migraine, anemia, cancer, hyperglycemia, hypertension, diabetes mellitus, and oxidative stress directly or indirectly. The riboflavin deficiency has profound effect on iron absorption, metabolism of tryptophan, mitochondrial dysfunction, gastrointestinal tract, brain dysfunction, and metabolism of other vitamins as well as is associated with skin disorders. Toxicological and photosensitizing properties of riboflavin make it suitable for biological use, such as virus inactivation, excellent photosensitizer, and promising adjuvant in chemo radiotherapy in cancer treatment. A number of recent studies have indicated and highlighted the cellular processes and biological effects associated with riboflavin supplementation in metabolic diseases. Overall, a deeper understanding of these emerging roles of riboflavin intake is essential to design better therapies for future.
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Affiliation(s)
- Kiran Thakur
- a Dairy Microbiology Division , ICAR-National Dairy Research Institute , Karnal , Haryana , India
| | - Sudhir Kumar Tomar
- a Dairy Microbiology Division , ICAR-National Dairy Research Institute , Karnal , Haryana , India
| | - Ashish Kumar Singh
- b Dairy Technology Division , ICAR-National Dairy Research Institute , Karnal , Haryana , India
| | - Surajit Mandal
- a Dairy Microbiology Division , ICAR-National Dairy Research Institute , Karnal , Haryana , India
| | - Sumit Arora
- c Dairy Chemistry Division , ICAR-National Dairy Research Institute , Karnal , Haryana , India
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18
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Lakhan R, Subramanian VS, Said HM. Role of MicroRNA-423-5p in posttranscriptional regulation of the intestinal riboflavin transporter-3. Am J Physiol Gastrointest Liver Physiol 2017; 313:G589-G598. [PMID: 28912250 PMCID: PMC5814671 DOI: 10.1152/ajpgi.00238.2017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 09/06/2017] [Accepted: 09/06/2017] [Indexed: 01/31/2023]
Abstract
Riboflavin (RF) is essential for normal cellular functions and health. Humans obtain RF from exogenous sources via intestinal absorption that involves a highly specific carrier-mediated process. We have recently established that the riboflavin transporter-3 (RFVT3) is vital for the normal intestinal RF uptake process and have characterized certain aspects of its transcriptional regulation. Little is known, however, about how this transporter is regulated at the posttranscriptional level. We address this issue by focusing on the role of microRNAs. Using bioinformatics, we identified two potential interacting miRNAs with the human (h) RFVT3-3'-UTR, and showed (using pmirGLO-hRFVT3-3'-UTR) that the hRFVT3-3'-UTR is, indeed, a target for miRNA effect. Of the two putative miRNAs identified, miR-423-5p was found to be highly expressed in intestinal epithelial cells and that its mimic affected luciferase reporter activity of the pmirGLO-hRFVT3-3'-UTR construct, and also led to inhibition in RF uptake by intestinal epithelial Caco-2 and HuTu-80 cells. Furthermore, cells transfected with mutated seed sequences for miR-423-5p showed an abrogation in inhibitory effect of the miR-423-5p mimic on luciferase activity. While miR-423-5p did not affect the level of expression of the hRFVT3 mRNA, it did lead to a significant inhibition in the level of expression of its protein. Similarly, miR-423-5p was found to affect the level of expression of the mouse RFVT3 in cultured intestinal enteroids. These findings demonstrate, for the first time, that the RFVT3 is a target for posttranscriptional regulation by miRNAs in intestinal epithelial cells and that this regulation has functional consequences on intestinal RF uptake.NEW & NOTEWORTHY Our findings show for the first time that RFVT3 is a target for posttranscriptional regulation by miR-423-5p in intestinal epithelial cells, and this regulation has functional consequences on intestinal riboflavin (RF) uptake process.
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Affiliation(s)
- Ram Lakhan
- Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California; and Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California
| | - Veedamali S. Subramanian
- Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California; and Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California
| | - Hamid M. Said
- Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California; and Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California
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19
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Udhayabanu T, Karthi S, Mahesh A, Varalakshmi P, Manole A, Houlden H, Ashokkumar B. Adaptive regulation of riboflavin transport in heart: effect of dietary riboflavin deficiency in cardiovascular pathogenesis. Mol Cell Biochem 2017; 440:147-156. [PMID: 28836047 DOI: 10.1007/s11010-017-3163-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 08/16/2017] [Indexed: 01/09/2023]
Abstract
Deficiency or defective transport of riboflavin (RF) is known to cause neurological disorders, cataract, cardiovascular anomalies, and various cancers by altering the biochemical pathways. Mechanisms and regulation of RF uptake process is well characterized in the cells of intestine, liver, kidney, and brain origin, while very little is known in the heart. Hence, we aimed to understand the expression and regulation of RF transporters (rRFVT-1 and rRFVT-2) in cardiomyocytes during RF deficiency and also investigated the role of RF in ischemic cardiomyopathy and mitochondrial dysfunction in vivo. Riboflavin uptake assay revealed that RF transport in H9C2 is (1) significantly higher at pH 7.5, (2) independent of Na+ and (3) saturable with a Km of 3.746 µM. For in vivo studies, male Wistar rats (110-130 g) were provided riboflavin deficient food containing 0.3 ± 0.05 mg/kg riboflavin for 7 weeks, which resulted in over expression of both RFVTs in mRNA and protein level. RF deprivation resulted in the accumulation of cardiac biomarkers, histopathological abnormalities, and reduced mitochondrial membrane potential which evidenced the key role of RF in the development of cardiovascular pathogenesis. Besides, adaptive regulation of RF transporters upon RF deficiency signifies that RFVTs can be considered as an effective delivery system for drugs against cardiac diseases.
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Affiliation(s)
- Tamilarasan Udhayabanu
- Department of Genetic Engineering, School of Biotechnology, Madurai Kamaraj University, Madurai, 625021, India
| | - Sellamuthu Karthi
- Department of Genetic Engineering, School of Biotechnology, Madurai Kamaraj University, Madurai, 625021, India
| | - Ayyavu Mahesh
- Centre for Excellence in Genomics Science, School of Biological Sciences, Madurai Kamaraj University, Madurai, 625021, India
| | - Perumal Varalakshmi
- Department of Molecular Microbiology, School of Biotechnology, Madurai Kamaraj University, Madurai, 625021, India
| | - Andreea Manole
- Department of Molecular Neuroscience and Neurogenetics Laboratory, UCL Institute of Neurology, Queen Square, London, WC1N 3BG, UK
| | - Henry Houlden
- Department of Molecular Neuroscience and Neurogenetics Laboratory, UCL Institute of Neurology, Queen Square, London, WC1N 3BG, UK
| | - Balasubramaniem Ashokkumar
- Department of Genetic Engineering, School of Biotechnology, Madurai Kamaraj University, Madurai, 625021, India.
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20
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Mitchell R. Methods in Micronutrient Metabolism. J Acad Nutr Diet 2017; 117:1157-1163. [DOI: 10.1016/j.jand.2016.07.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Indexed: 11/26/2022]
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21
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Subramanian VS, Sabui S, Teafatiller T, Bohl JA, Said HM. Structure/functional aspects of the human riboflavin transporter-3 ( SLC52A3): role of the predicted glycosylation and substrate-interacting sites. Am J Physiol Cell Physiol 2017; 313:C228-C238. [PMID: 28637675 PMCID: PMC5582875 DOI: 10.1152/ajpcell.00101.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 06/05/2017] [Accepted: 06/16/2017] [Indexed: 11/22/2022]
Abstract
The human riboflavin (RF) transporter-3 (hRFVT-3; product of the SLC52A3 gene) plays an essential role in the intestinal RF absorption process and is expressed exclusively at the apical membrane domain of polarized enterocytes. Previous studies have characterized different physiological/biological aspects of this transporter, but nothing is known about the glycosylation status of the hRFVT-3 protein and role of this modification in its physiology/biology. Additionally, little is known about the residues in the hRFVT-3 protein that interact with the ligand, RF. We addressed these issues using appropriate biochemical/molecular approaches, a protein-docking model, and established intestinal/renal epithelial cells. Our results showed that the hRFVT-3 protein is glycosylated and that glycosylation is important for its function. Mutating the predicted N-glycosylation sites at Asn94 and Asn168 led to a significant decrease in RF uptake; it also led to a marked intracellular (in the endoplasmic reticulum, ER) retention of the mutated proteins as shown by live-cell confocal imaging studies. The protein-docking model used in this study has identified a number of putative substrate-interacting sites: Ser16, Ile20, Trp24, Phe142, Thr314, and Asn315 Mutating these potential interacting sites was indeed found to lead to a significant inhibition in RF uptake and to intracellular (ER) retention of the mutated proteins (except for the Phe142 mutant). These results demonstrate that the hRFVT-3 protein is glycosylated and this glycosylation is important for its function and cell surface expression. This study also identified a number of residues in the hRFVT-3 polypeptide that are important for its function/cell surface expression.
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Affiliation(s)
- Veedamali S Subramanian
- Departments of Medicine, Physiology/Biophysics, University of California, Irvine, California; and Department of Veterans Affairs Medical Center, Long Beach, California
| | - Subrata Sabui
- Departments of Medicine, Physiology/Biophysics, University of California, Irvine, California; and Department of Veterans Affairs Medical Center, Long Beach, California
| | - Trevor Teafatiller
- Departments of Medicine, Physiology/Biophysics, University of California, Irvine, California; and Department of Veterans Affairs Medical Center, Long Beach, California
| | - Jennifer A Bohl
- Departments of Medicine, Physiology/Biophysics, University of California, Irvine, California; and Department of Veterans Affairs Medical Center, Long Beach, California
| | - Hamid M Said
- Departments of Medicine, Physiology/Biophysics, University of California, Irvine, California; and Department of Veterans Affairs Medical Center, Long Beach, California
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22
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Li SS, Xu YW, Wu JY, Tan HZ, Wu ZY, Xue YJ, Zhang JJ, Li EM, Xu LY. Plasma Riboflavin Level is Associated with Risk, Relapse, and Survival of Esophageal Squamous Cell Carcinoma. Nutr Cancer 2017; 69:21-28. [PMID: 27898225 DOI: 10.1080/01635581.2017.1247890] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Riboflavin is an essential micronutrient for normal cellular activity, and deficiency may result in disease, such as cancer. We performed a case-control study to explore the association of riboflavin levels with risk and prognosis of esophageal squamous cell carcinoma (ESCC). Plasma riboflavin levels, as measured by enzyme-linked immunosorbent assay (ELISA), in ESCC patients were significantly lower than in those of healthy controls (7.04 ± 6.34 ng/ml vs. 9.32 ± 12.40 ng/ml; P < 0.05). Moreover, there was an inverse relationship between riboflavin level and risk of ESCC (odds ratio (OR) = 0.97, 95% confidence interval (CI) = 0.95-0.99, P = 0.02). The 5-year relapse-free and overall survival rates were significantly lower when riboflavin levels were ≤0.8 ng/ml than >0.8 ng/ml (relapse-free survival rate: 29.4% vs. 54.8%; overall survival rate: 28.6% vs. 55.6%). Plasma riboflavin level was an independent protective factor for both relapse-free (hazard ratio (HR) = 0.325, 95% CI = 0.161-0.657, P = 0.002) and overall survival of ESCC patients (HR = 0.382, 95% CI = 0.190-0.768, P = 0.007). In conclusion, plasma riboflavin levels are significantly related to risk and prognosis of ESCC patients, suggesting that moderate supplementation of riboflavin will decrease risk and prevent recurrence of ESCC and also improve prognosis of ESCC patients.
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Affiliation(s)
- Shan-Shan Li
- a Key Laboratory of Molecular Biology in High Cancer Incidence Coastal Chaoshan Area of Guangdong Higher Education Institutes, Shantou University Medical College , Shantou , China
- b Department of Public Health , Shantou University Medical College , Shantou , China
- c Department of Biochemistry and Molecular Biology , Shantou University Medical College , Shantou , China
| | - Yi-Wei Xu
- a Key Laboratory of Molecular Biology in High Cancer Incidence Coastal Chaoshan Area of Guangdong Higher Education Institutes, Shantou University Medical College , Shantou , China
- c Department of Biochemistry and Molecular Biology , Shantou University Medical College , Shantou , China
- d Department of Clinical Laboratory , the Cancer Hospital of Shantou University Medical College , Shantou , China
| | - Jian-Yi Wu
- a Key Laboratory of Molecular Biology in High Cancer Incidence Coastal Chaoshan Area of Guangdong Higher Education Institutes, Shantou University Medical College , Shantou , China
- c Department of Biochemistry and Molecular Biology , Shantou University Medical College , Shantou , China
| | - Hua-Zhen Tan
- a Key Laboratory of Molecular Biology in High Cancer Incidence Coastal Chaoshan Area of Guangdong Higher Education Institutes, Shantou University Medical College , Shantou , China
- b Department of Public Health , Shantou University Medical College , Shantou , China
- c Department of Biochemistry and Molecular Biology , Shantou University Medical College , Shantou , China
| | - Zhi-Yong Wu
- e Department of Oncologic Surgery , Shantou Central Hospital, Affiliated Shantou Hospital of Sun Yat-Sen University , Shantou , China
| | - Yu-Jie Xue
- a Key Laboratory of Molecular Biology in High Cancer Incidence Coastal Chaoshan Area of Guangdong Higher Education Institutes, Shantou University Medical College , Shantou , China
- f Department of Pathology , Shantou University Medical College , Shantou , China
| | - Jian-Jun Zhang
- a Key Laboratory of Molecular Biology in High Cancer Incidence Coastal Chaoshan Area of Guangdong Higher Education Institutes, Shantou University Medical College , Shantou , China
- b Department of Public Health , Shantou University Medical College , Shantou , China
| | - En-Min Li
- a Key Laboratory of Molecular Biology in High Cancer Incidence Coastal Chaoshan Area of Guangdong Higher Education Institutes, Shantou University Medical College , Shantou , China
- c Department of Biochemistry and Molecular Biology , Shantou University Medical College , Shantou , China
| | - Li-Yan Xu
- a Key Laboratory of Molecular Biology in High Cancer Incidence Coastal Chaoshan Area of Guangdong Higher Education Institutes, Shantou University Medical College , Shantou , China
- f Department of Pathology , Shantou University Medical College , Shantou , China
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23
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Beztsinna N, Tsvetkova Y, Bartneck M, Lammers T, Kiessling F, Bestel I. Amphiphilic Phospholipid-Based Riboflavin Derivatives for Tumor Targeting Nanomedicines. Bioconjug Chem 2016; 27:2048-61. [DOI: 10.1021/acs.bioconjchem.6b00317] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Nataliia Beztsinna
- Institute of Chemistry & Biology of Membranes & Nano-objects, CBMN UMR 5248, Bordeaux University, 33600 Pessac, France
| | - Yoanna Tsvetkova
- Experimental
Molecular Imaging, RWTH Aachen University Clinic, 52056 Aachen, Germany
| | - Matthias Bartneck
- Gastroenterology
and Metabolic Disorders, RWTH Aachen University Clinic, 52056 Aachen, Germany
| | - Twan Lammers
- Experimental
Molecular Imaging, RWTH Aachen University Clinic, 52056 Aachen, Germany
| | - Fabian Kiessling
- Experimental
Molecular Imaging, RWTH Aachen University Clinic, 52056 Aachen, Germany
| | - Isabelle Bestel
- Institute of Chemistry & Biology of Membranes & Nano-objects, CBMN UMR 5248, Bordeaux University, 33600 Pessac, France
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24
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Barile M, Giancaspero TA, Leone P, Galluccio M, Indiveri C. Riboflavin transport and metabolism in humans. J Inherit Metab Dis 2016; 39:545-57. [PMID: 27271694 DOI: 10.1007/s10545-016-9950-0] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Revised: 05/12/2016] [Accepted: 05/19/2016] [Indexed: 12/17/2022]
Abstract
Recent studies elucidated how riboflavin transporters and FAD forming enzymes work in humans and create a coordinated flavin network ensuring the maintenance of cellular flavoproteome. Alteration of this network may be causative of severe metabolic disorders such as multiple acyl-CoA dehydrogenase deficiency (MADD) or Brown-Vialetto-van Laere syndrome. A crucial step in the maintenance of FAD homeostasis is riboflavin uptake by plasma and mitochondrial membranes. Therefore, studies on recently identified human plasma membrane riboflavin transporters are presented, together with those in which still unidentified mitochondrial riboflavin transporter(s) have been described. A main goal of future research is to fill the gaps still existing as for some transcriptional, functional and structural details of human FAD synthases (FADS) encoded by FLAD1 gene, a novel "redox sensing" enzyme. In the frame of the hypothesis that FADS, acting as a "FAD chaperone", could play a crucial role in the biogenesis of mitochondrial flavo-proteome, several basic functional aspects of flavin cofactor delivery to cognate apo-flavoenzyme are also briefly dealt with. The establishment of model organisms performing altered FAD homeostasis will improve the molecular description of human pathologies. The molecular and functional studies of transporters and enzymes herereported, provide guidelines for improving therapies which may have beneficial effects on the altered metabolism.
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Affiliation(s)
- Maria Barile
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari "Aldo Moro", via Orabona 4, I-70126, Bari, Italy.
| | - Teresa Anna Giancaspero
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari "Aldo Moro", via Orabona 4, I-70126, Bari, Italy
| | - Piero Leone
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari "Aldo Moro", via Orabona 4, I-70126, Bari, Italy
| | - Michele Galluccio
- Dipartimento DiBEST (Biologia, Ecologia, Scienze della Terra), Unità di Biochimica e Biotecnologie Molecolari, Università della Calabria, via Bucci 4c, I-87036, Arcavacata di Rende, Italy
| | - Cesare Indiveri
- Dipartimento DiBEST (Biologia, Ecologia, Scienze della Terra), Unità di Biochimica e Biotecnologie Molecolari, Università della Calabria, via Bucci 4c, I-87036, Arcavacata di Rende, Italy
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Disruption of Slc52a3 gene causes neonatal lethality with riboflavin deficiency in mice. Sci Rep 2016; 6:27557. [PMID: 27272163 PMCID: PMC4897618 DOI: 10.1038/srep27557] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 05/18/2016] [Indexed: 12/03/2022] Open
Abstract
Homeostasis of riboflavin should be maintained by transporters. Previous in vitro studies have elucidated basic information about riboflavin transporter RFVT3 encoded by SLC52A3 gene. However, the contribution of RFVT3 to the maintenance of riboflavin homeostasis and the significance in vivo remain unclear. Here, we investigated the physiological role of RFVT3 using Slc52a3 knockout (Slc52a3−/−) mice. Most Slc52a3−/− mice died with hyperlipidemia and hypoglycemia within 48 hr after birth. The plasma and tissue riboflavin concentrations in Slc52a3−/− mice at postnatal day 0 were dramatically lower than those in wild-type (WT) littermates. Slc52a3−/− fetuses showed a lower capacity of placental riboflavin transport compared with WT fetuses. Riboflavin supplement during pregnancy and after birth reduced neonatal death and metabolic disorders. To our knowledge, this is the first report to indicate that Rfvt3 contributes to placental riboflavin transport, and that disruption of Slc52a3 gene caused neonatal mortality with hyperlipidemia and hypoglycemia owing to riboflavin deficiency.
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Gandhimathi K, Karthi S, Manimaran P, Varalakshmi P, Ashokkumar B. Riboflavin transporter-2 (rft-2) of Caenorhabditis elegans: Adaptive and developmental regulation. J Biosci 2016; 40:257-68. [PMID: 25963255 DOI: 10.1007/s12038-015-9512-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Riboflavin transporters (rft-1 and rft-2), orthologous to human riboflavin transporter-3 (hRVFT-3), are identified and characterized in Caenorhabditis elegans. However, studies pertaining to functional contribution of rft-2 in maintaining body homeostatic riboflavin levels and its regulation are very limited. In this study, the expression pattern of rft-2 at different life stages of C. elegans was studied through real-time PCR, and found to be consistent from larval to adult stages that demonstrate its involvement in maintaining the body homeostatic riboflavin levels at whole animal level all through its life. A possible regulation of rft-2 expression at mRNA levels at whole animal was studied after adaptation to low and high concentrations of riboflavin. Abundance of rft-2 transcript was upregulated in riboflavin-deficient conditions (10 nM), while it was downregulated with riboflavin-supplemented conditions (2 mM) as compared with control (10 meu M). Further, the 5'-regulatory region of the rft-2 gene was cloned, and transgenic nematodes expressing transcriptional rft-2 promoter::GFP fusion constructs were generated. The expression of rft-2 was found to be adaptively regulated in vivo when transgenic worms were maintained under different extracellular riboflavin levels, which was also mediated partly via changes in the rft-2 levels that directs towards the possible involvement of transcriptional regulatory events.
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Affiliation(s)
- Krishnan Gandhimathi
- Department of Genetic Engineering, School of Biotechnology, Madurai Kamaraj University, Madurai 625 021, India
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Subramanian VS, Lambrecht N, Lytle C, Said HM. Conditional (intestinal-specific) knockout of the riboflavin transporter-3 (RFVT-3) impairs riboflavin absorption. Am J Physiol Gastrointest Liver Physiol 2016; 310:G285-93. [PMID: 26660539 PMCID: PMC4754740 DOI: 10.1152/ajpgi.00340.2015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 12/02/2015] [Indexed: 01/31/2023]
Abstract
Riboflavin (RF) is indispensable for normal cell metabolism, proliferation, and growth. The RFVT-3 protein (product of the Slc52a3 gene) is expressed in the gut with the expression being restricted to the apical membrane domain of the polarized intestinal epithelial cells. The relative contribution of RFVT-3 to total carrier-mediated RF uptake in the native intestine, however, is not clear. We addressed this issue in the current investigation using a conditional (intestinal-specific) RFVT-3 knockout (cKO) mouse model developed by the Cre/Lox approach. All RFVT-3 cKO mice were found to be RF deficient and showed a significant growth and development retardation; also, nearly two-thirds of them died prematurely between the age of 6 and 12 wk. In vivo (intestinal and colonic loops) and in vitro (native isolated intestinal epithelial cells) uptake studies showed a severe inhibition in carrier-mediated RF uptake in the cKO mice compared with control littermates. We also observed a significant increase in the level of expression of oxidative stress-responsive genes in the intestine of the cKO mice compared with control littermates. Supplementation of the RFVT-3 cKO mice with pharmacological doses of RF led to a complete correction of the growth retardation and to normalization in the level of expression of the oxidative stress-responsive genes in the gut. These results show, for the first time, that the RFVT-3 system is the main transporter involved in carrier-mediated RF uptake in the native mouse small and large intestine, and that its dysfunction impairs normal RF body homeostasis.
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Affiliation(s)
- Veedamali S. Subramanian
- 1Departments of Medicine, Physiology and Biophysics, University of California, Irvine, California; ,2Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California; and
| | - Nils Lambrecht
- 2Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California; and
| | - Christian Lytle
- 3Division of Biomedical Sciences, University of California, Riverside, California
| | - Hamid M. Said
- 1Departments of Medicine, Physiology and Biophysics, University of California, Irvine, California; ,2Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California; and
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Wu AML, Dedina L, Dalvi P, Yang M, Leon-Cheon J, Earl B, Harper PA, Ito S. Riboflavin uptake transporter Slc52a2 (RFVT2) is upregulated in the mouse mammary gland during lactation. Am J Physiol Regul Integr Comp Physiol 2016; 310:R578-85. [PMID: 26791833 DOI: 10.1152/ajpregu.00507.2015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 01/16/2016] [Indexed: 12/13/2022]
Abstract
While it is well recognized that riboflavin accumulates in breast milk as an essential vitamin for neonates, transport mechanisms for its milk excretion are not well characterized. The multidrug efflux transporter ABCG2 in the apical membrane of milk-producing mammary epithelial cells (MECs) is involved with riboflavin excretion. However, it is not clear whether MECs possess other riboflavin transport systems, which may facilitate its basolateral uptake into MECs. We report here that transcripts encoding the second (SLC52A2) and third (SLC52A3) member of the recently discovered family of SLC52A riboflavin uptake transporters are expressed in milk fat globules from human breast milk. Furthermore, Slc52a2 and Slc52a3 mRNA are upregulated in the mouse mammary gland during lactation. Importantly, the induction ofSlc52a2, which was the major Slc52a riboflavin transporter in the lactating mammary gland, was also observed at the protein level. Subcellular localization studies showed that green fluorescent protein-tagged mouse SLC52A2 mainly localized to the cell membrane, with no preferential distribution to the apical or basolateral membrane in polarized kidney MDCK cells. These results strongly implicate a potential role for SLC52A2 in riboflavin uptake by milk-producing MECs, a critical step in the transfer of riboflavin into breast milk.
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Affiliation(s)
- Alex Man Lai Wu
- Physiology and Experimental Medicine Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada; and Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada; and
| | - Liana Dedina
- Physiology and Experimental Medicine Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada; and Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada; and
| | - Pooja Dalvi
- Physiology and Experimental Medicine Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada; and
| | - Mingdong Yang
- Physiology and Experimental Medicine Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada; and
| | - John Leon-Cheon
- Physiology and Experimental Medicine Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada; and Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada; and
| | - Brian Earl
- Physiology and Experimental Medicine Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada; and
| | - Patricia A Harper
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada; and
| | - Shinya Ito
- Physiology and Experimental Medicine Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada; and Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada; and Department of Paediatrics, University of Toronto, Toronto, Ontario, Canada
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Jayapaul J, Arns S, Bunker M, Weiler M, Rutherford S, Comba P, Kiessling F. In vivo evaluation of riboflavin receptor targeted fluorescent USPIO in mice with prostate cancer xenografts. NANO RESEARCH 2016; 9:1319-1333. [PMID: 27738498 DOI: 10.1007/s12274-016-1028-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 01/21/2016] [Accepted: 01/24/2016] [Indexed: 05/21/2023]
Abstract
UNLABELLED Riboflavin (Rf) receptors bind and translocate Rf and its phosphorylated forms (e.g. flavin mononucleotide, FMN) into cells where they mediate various cellular metabolic pathways. Previously, we showed that FMN-coated ultrasmall superparamagnetic iron oxide (FLUSPIO) nanoparticles are suitable for labeling metabolically active cancer and endothelial cells in vitro. In this study, we focused on the in vivo application of FLUSPIO using prostate cancer xenografts. Size, charge, and chemical composition of FLUSPIO were evaluated. We explored the in vitro specificity of FLUSPIO for its cellular receptors using magnetic resonance imaging (MRI) and Prussian blue staining. Competitive binding experiments were performed in vivo by injecting free FMN in excess. Bio-distribution of FLUSPIO was determined by estimating iron content in organs and tumors using a colorimetric assay. AFM analysis and zeta potential measurements revealed a particulate morphology approximately 20-40 nm in size and a negative zeta potential (-24.23 ± 0.15 mV) in water. X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry data confirmed FMN present on the USPIO nanoparticle surface. FLUSPIO uptake in prostate cancer cells and human umbilical vein endothelial cells was significantly higher than that of control USPIO, while addition of excess of free FMN reduced accumulation. Similarly, in vivo MRI and histology showed specific FLUSPIO uptake by prostate cancer cells, tumor endothelial cells, and tumor-associated macrophages. Besides prominent tumor accumulation, FLUSPIO accumulated in the liver, spleen, lung, and skin. Hence, our data strengthen our hypothesis that targeting riboflavin receptors is an efficient approach to accumulate nanomedicines in tumors opening perspectives for the development of diagnostic and therapeutic systems. ELECTRONIC SUPPLEMENTARY MATERIAL Supplementary material is available for this article at 10.1007/s12274-016-1028-7 and is accessible for authorized users.
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Affiliation(s)
- Jabadurai Jayapaul
- Institute for Experimental Molecular Imaging, RWTH Aachen University, Pauwelsstrasse 30, Aachen, 52074 Germany ; Anorganisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 270, Heidelberg, 69120 Germany ; Molecular Imaging Group, Department of Structural Biology, Leibniz Institut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, Berlin, 13125 Germany
| | - Susanne Arns
- Institute for Experimental Molecular Imaging, RWTH Aachen University, Pauwelsstrasse 30, Aachen, 52074 Germany
| | - Matt Bunker
- AstraZeneca, Pharmaceutical Development, Charter Way, Macclesfield, Cheshire, SK10 2NA UK ; Molecular Profiles Ltd., 8 Orchard Place, Nottingham Business Park, Nottingham, NG8 6PX UK
| | - Marek Weiler
- Institute for Experimental Molecular Imaging, RWTH Aachen University, Pauwelsstrasse 30, Aachen, 52074 Germany
| | - Sandra Rutherford
- Molecular Profiles Ltd., 8 Orchard Place, Nottingham Business Park, Nottingham, NG8 6PX UK
| | - Peter Comba
- Anorganisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 270, Heidelberg, 69120 Germany
| | - Fabian Kiessling
- Institute for Experimental Molecular Imaging, RWTH Aachen University, Pauwelsstrasse 30, Aachen, 52074 Germany
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Subramanian VS, Ghosal A, Kapadia R, Nabokina SM, Said HM. Molecular Mechanisms Mediating the Adaptive Regulation of Intestinal Riboflavin Uptake Process. PLoS One 2015; 10:e0131698. [PMID: 26121134 PMCID: PMC4484800 DOI: 10.1371/journal.pone.0131698] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Accepted: 06/04/2015] [Indexed: 12/16/2022] Open
Abstract
The intestinal absorption process of vitamin B2 (riboflavin, RF) is carrier-mediated, and all three known human RF transporters, i.e., hRFVT-1, -2, and -3 (products of the SLC52A1, 2 & 3 genes, respectively) are expressed in the gut. We have previously shown that the intestinal RF uptake process is adaptively regulated by substrate level, but little is known about the molecular mechanism(s) involved. Using human intestinal epithelial NCM460 cells maintained under RF deficient and over-supplemented (OS) conditions, we now show that the induction in RF uptake in RF deficiency is associated with an increase in expression of the hRFVT-2 & -3 (but not hRFVT-1) at the protein and mRNA levels. Focusing on hRFVT-3, the predominant transporter in the intestine, we also observed an increase in the level of expression of its hnRNA and activity of its promoter in the RF deficiency state. An increase in the level of expression of the nuclear factor Sp1 (which is important for activity of the SLC52A3 promoter) was observed in RF deficiency, while mutating the Sp1/GC site in the SLC52A3 promoter drastically decreased the level of induction in SLC52A3 promoter activity in RF deficiency. We also observed specific epigenetic changes in the SLC52A3 promoter in RF deficiency. Finally, an increase in hRFVT-3 protein expression at the cell surface was observed in RF deficiency. Results of these investigations show, for the first time, that transcriptional and post-transcriptional mechanisms are involved in the adaptive regulation of intestinal RF uptake by the prevailing substrate level.
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Affiliation(s)
- Veedamali S. Subramanian
- Department of Medicine, University of California, Irvine, California, United States of America
- VAMC, Long Beach, California, United States of America
| | - Abhisek Ghosal
- Department of Medicine, University of California, Irvine, California, United States of America
- VAMC, Long Beach, California, United States of America
| | - Rubina Kapadia
- Department of Medicine, University of California, Irvine, California, United States of America
- VAMC, Long Beach, California, United States of America
| | - Svetlana M. Nabokina
- Department of Medicine, University of California, Irvine, California, United States of America
- VAMC, Long Beach, California, United States of America
| | - Hamid M. Said
- Department of Medicine, University of California, Irvine, California, United States of America
- Department of Physiology/Biophysics, University of California, Irvine, California, United States of America
- VAMC, Long Beach, California, United States of America
- * E-mail:
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31
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Subramanian VS, Kapadia R, Ghosal A, Said HM. Identification of residues/sequences in the human riboflavin transporter-2 that is important for function and cell biology. Nutr Metab (Lond) 2015; 12:13. [PMID: 25798182 PMCID: PMC4367879 DOI: 10.1186/s12986-015-0008-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 02/18/2015] [Indexed: 11/26/2022] Open
Abstract
Background Riboflavin (RF) is essential for normal cellular metabolic activities. Human cells obtain RF from their surroundings via a carrier-mediated process that involves RF transporters -1, -2 & -3 (hRFVT -1, -2 & -3; products of SLC52A1, -A2 and -A3 genes, respectively). Little is known about the structural features of these transporters that are important for their function/cell biology. Our aim in this study was to address these issues for the hRFVT-2, a transporter linked to the neurodegenerative disorder Brown-Vialetto-Van Laere Syndrome (BVVLS). Methods We used comparative protein-structure modelling to predict residues that interact with two amino acids known to be critical for hRFVT-2 function (the clinical mutants L123 and L339), site-directed mutagenesis, and truncation approach in the human-derived brain U87 cell model. Results First we showed that the defect in the function of the L123 and L339 hRFVT-2 clinical mutants is related to a reduction in protein stability/translation efficiency and to retention of the protein in the ER. Mutating V120 and L121 (residues predicted to interact with L123) and L342 (a residue predicted to interact with L339) also led to a significant inhibition in hRFVT-2 function (with no change in membrane expression); this inhibition was associated with changes in protein stability/translation efficiency (in the case of V120A and L342A) and an impairment in transport function (in the case of L121). Truncating the N- and C- terminals of hRFVT-2 led to significant inhibition in RF uptake, which was associated with changes in protein stability/translation efficiency (it was also associated with a partial impairment in membrane targeting in the case of the N-terminal truncation). Conclusion These investigations report on identification of residues/sequences in the hRFVT-2 protein that is important for its physiological function and cell biology.
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Affiliation(s)
- Veedamali S Subramanian
- Departments of Medicine, Physiology/Biophysics, University of California, Irvine, CA 92697 USA ; Department of Veterans Affairs Medical Center, Long Beach, CA 90822 USA
| | - Rubina Kapadia
- Departments of Medicine, Physiology/Biophysics, University of California, Irvine, CA 92697 USA ; Department of Veterans Affairs Medical Center, Long Beach, CA 90822 USA
| | - Abhisek Ghosal
- Departments of Medicine, Physiology/Biophysics, University of California, Irvine, CA 92697 USA ; Department of Veterans Affairs Medical Center, Long Beach, CA 90822 USA
| | - Hamid M Said
- Departments of Medicine, Physiology/Biophysics, University of California, Irvine, CA 92697 USA ; Department of Veterans Affairs Medical Center, Long Beach, CA 90822 USA
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Ghosal A, Sabui S, Said HM. Identification and characterization of the minimal 5'-regulatory region of the human riboflavin transporter-3 (SLC52A3) in intestinal epithelial cells. Am J Physiol Cell Physiol 2014; 308:C189-96. [PMID: 25394472 DOI: 10.1152/ajpcell.00342.2014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The human riboflavin (RF) transporter-3 (product of the SLC52A3 gene) plays an important role in intestinal RF absorption. Our aims in this study were to identify the minimal 5'-regulatory region of the SLC52A3 gene and the regulatory element(s) involved in its activity in intestinal epithelial cells, as well as to confirm promoter activity and establish physiological relevance in vivo in transgenic mice. With the use of transiently transfected human intestinal epithelial HuTu 80 cells and 5'-deletion analysis, the minimal SLC52A3 promoter was found to be encoded between -199 and +8 bp (using the start of the transcription start site as position 1). Although several putative cis-regulatory elements were predicted in this region, only the stimulating protein-1 (Sp1) binding site (at position -74/-71 bp) was found to play a role in promoter activity, as indicated by mutational analysis. Binding of Sp1 to the minimal SLC52A3 promoter was demonstrated by means of EMSA and supershift assays and by chromatin immunoprecipitation analysis. Studies with Drosophila SL2 cells (which lack Sp activity) confirmed the importance of Sp1 in driving the activity of the SLC52A3 minimal promoter; they further showed that Sp3 can also do the activation. Finally, with the use of luciferase gene fusions, the activity of the cloned SLC52A3 promoter was confirmed in vivo in transgenic mice. These studies report, for the first time, on the identification and characterization of the SLC52A3 promoter and also demonstrate the importance of Sp1 in regulating its activity in intestinal epithelial cells.
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Affiliation(s)
- Abhisek Ghosal
- Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California; and Department of Veterans Affairs Medical Center, Long Beach, California
| | - Subrata Sabui
- Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California; and Department of Veterans Affairs Medical Center, Long Beach, California
| | - Hamid M Said
- Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California; and Department of Veterans Affairs Medical Center, Long Beach, California
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Resendez A, Abdul Halim M, Landhage CM, Hellström PM, Singaram B, Webb DL. Rapid small intestinal permeability assay based on riboflavin and lactulose detected by bis-boronic acid appended benzyl viologens. Clin Chim Acta 2014; 439:115-21. [PMID: 25300228 PMCID: PMC5766262 DOI: 10.1016/j.cca.2014.09.031] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 09/24/2014] [Accepted: 09/29/2014] [Indexed: 12/17/2022]
Abstract
Background Although organoboronic acids are efficient high-throughput sugar sensors, they have not been pursued for gut permeability studies. A modification of the lactulose/mannitol assay is described by which small intestinal permeability is assessed at the time of urine collection using a lactulose/riboflavin ratio. Methods Volunteers ingested 50 mg riboflavin and either 5 g mannitol or 10 g lactulose. Urine was collected for 6 hrs. Riboflavin was assayed by autofluorescence. Riboflavin was removed by C18 solid phase extraction. Lactulose and mannitol were then assayed using 1,1′-bis(2-boronobenzyl)-4,4′-bipyridinium (4,4′oBBV) coupled to the fluorophore HPTS. Results The temporal profile over 6 hrs for riboflavin paralleled mannitol. Riboflavin recovery in urine was 11.1 ± 1.9 % (mean ± SEM, n = 7), similar to mannitol. There was selective binding of 4,4′oBBV to lactulose, likely involving cooperativity between the fructose and galactose moieties. Lower limits of detection and quantification were 90 and 364 μM. The lactulose assay was insensitive to other permeability probes (e.g., sucrose, sucralose) while tolerating glucose or lactose. This assay can be adapted to automated systems. Stability of 4,4′oBBV exceeds 4 years. Conclusions Riboflavin measured by autofluorescence combined with lactulose measured with 4,4′oBBV represents a useful new chemistry for rapid measurement of intestinal permeability with excellent stability, cost and throughput benefits.
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Affiliation(s)
- Angel Resendez
- Department of Chemistry and Biochemistry, University of California at Santa Cruz, Santa Cruz, CA 95064, United States
| | - Md Abdul Halim
- Department of Medical Sciences, Gastroenterology and Hepatology Unit, Uppsala University, 751 85, Uppsala, Sweden
| | - Caroline M Landhage
- Department of Medical Sciences, Gastroenterology and Hepatology Unit, Uppsala University, 751 85, Uppsala, Sweden
| | - Per M Hellström
- Department of Medical Sciences, Gastroenterology and Hepatology Unit, Uppsala University, 751 85, Uppsala, Sweden
| | - Bakthan Singaram
- Department of Chemistry and Biochemistry, University of California at Santa Cruz, Santa Cruz, CA 95064, United States
| | - Dominic-Luc Webb
- Department of Chemistry and Biochemistry, University of California at Santa Cruz, Santa Cruz, CA 95064, United States; Department of Medical Sciences, Gastroenterology and Hepatology Unit, Uppsala University, 751 85, Uppsala, Sweden.
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Sabui S, Ghosal A, Said HM. Identification and characterization of 5'-flanking region of the human riboflavin transporter 1 gene (SLC52A1). Gene 2014; 553:49-56. [PMID: 25284511 DOI: 10.1016/j.gene.2014.10.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Revised: 09/30/2014] [Accepted: 10/02/2014] [Indexed: 12/16/2022]
Abstract
The human SLC52A1 gene encodes the riboflavin transporter-1 (RFVT-1), a plasma membrane protein that transports vitamin B2 (riboflavin, RF) into cells, and thus, plays a role in controlling cellular homeostasis of RF in those tissues that express the carrier protein (e.g. placenta and intestine). Currently, there is nothing known about transcriptional regulation of the SLC52A1 gene, therefore, we aimed to clone and characterize its 5'-flanking region. Using rapid amplification of the cDNA ends (5'-RACE), we identified one transcription start site (TSS). A 579 bp segment of the 5'-flanking region of this gene was cloned which exhibited robust promoter activity upon transfection in human intestinal epithelial cells. Deletion analysis revealed that the core promoter activity to be embedded in a region between -234 and -23 that lacked TATA element, was GC-rich, and harbored several putative cis-regulatory sites including KLFs, AP-2, EGRF and Sp-1. Mutating each of these sites led to a significant decrease in promoter activity (which was highest for the Sp-1 site), suggesting their possible involvement in regulating SLC52A1 transcription. Focusing on the Sp-1 site, EMSA, super-shift and ChIP analysis was performed that established the interaction of the Sp-1 transcription factor with the SLC52A1 promoter; also, co-transfection of the minimal SLC52A1 promoter with an Sp-1 containing vector in Drosophila SL-2 cells led to significant promoter activation. These results are the first to reveal the identity of the minimal SLC52A1 promoter and to establish an important role for Sp-1 in its activity.
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Affiliation(s)
- Subrata Sabui
- Department of Medicine and Physiology/Biophysics, University of California-Irvine, Irvine, CA 92697, USA; Department of Medical Research, Veterans Affairs Medical Center, Long Beach, CA 90822, USA
| | - Abhisek Ghosal
- Department of Medicine and Physiology/Biophysics, University of California-Irvine, Irvine, CA 92697, USA; Department of Medical Research, Veterans Affairs Medical Center, Long Beach, CA 90822, USA
| | - Hamid M Said
- Department of Medicine and Physiology/Biophysics, University of California-Irvine, Irvine, CA 92697, USA; Department of Medical Research, Veterans Affairs Medical Center, Long Beach, CA 90822, USA.
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Sahoo S, Aurich MK, Jonsson JJ, Thiele I. Membrane transporters in a human genome-scale metabolic knowledgebase and their implications for disease. Front Physiol 2014; 5:91. [PMID: 24653705 PMCID: PMC3949408 DOI: 10.3389/fphys.2014.00091] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Accepted: 02/17/2014] [Indexed: 01/18/2023] Open
Abstract
Membrane transporters enable efficient cellular metabolism, aid in nutrient sensing, and have been associated with various diseases, such as obesity and cancer. Genome-scale metabolic network reconstructions capture genomic, physiological, and biochemical knowledge of a target organism, along with a detailed representation of the cellular metabolite transport mechanisms. Since the first reconstruction of human metabolism, Recon 1, published in 2007, progress has been made in the field of metabolite transport. Recently, we published an updated reconstruction, Recon 2, which significantly improved the metabolic coverage and functionality. Human metabolic reconstructions have been used to investigate the role of metabolism in disease and to predict biomarkers and drug targets. Given the importance of cellular transport systems in understanding human metabolism in health and disease, we analyzed the coverage of transport systems for various metabolite classes in Recon 2. We will review the current knowledge on transporters (i.e., their preferred substrates, transport mechanisms, metabolic relevance, and disease association for each metabolite class). We will assess missing coverage and propose modifications and additions through a transport module that is functional when combined with Recon 2. This information will be valuable for further refinements. These data will also provide starting points for further experiments by highlighting areas of incomplete knowledge. This review represents the first comprehensive overview of the transporters involved in central metabolism and their transport mechanisms, thus serving as a compendium of metabolite transporters specific for human metabolic reconstructions.
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Affiliation(s)
- Swagatika Sahoo
- Center for Systems Biology, University of Iceland Reykjavik, Iceland ; Molecular Systems Physiology Group, Luxembourg Centre for Systems Biomedicine, University of Luxembourg Belval, Luxembourg
| | - Maike K Aurich
- Center for Systems Biology, University of Iceland Reykjavik, Iceland ; Molecular Systems Physiology Group, Luxembourg Centre for Systems Biomedicine, University of Luxembourg Belval, Luxembourg
| | - Jon J Jonsson
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Iceland Reykjavik, Iceland ; Department of Genetics and Molecular Medicine, Landspitali, National University Hospital of Iceland Reykjavik, Iceland
| | - Ines Thiele
- Center for Systems Biology, University of Iceland Reykjavik, Iceland ; Molecular Systems Physiology Group, Luxembourg Centre for Systems Biomedicine, University of Luxembourg Belval, Luxembourg
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Montalbetti N, Dalghi MG, Albrecht C, Hediger MA. Nutrient transport in the mammary gland: calcium, trace minerals and water soluble vitamins. J Mammary Gland Biol Neoplasia 2014; 19:73-90. [PMID: 24567109 DOI: 10.1007/s10911-014-9317-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 01/22/2014] [Indexed: 01/19/2023] Open
Abstract
Milk nutrients are secreted by epithelial cells in the alveoli of the mammary gland by several complex and highly coordinated systems. Many of these nutrients are transported from the blood to the milk via transcellular pathways that involve the concerted activity of transport proteins on the apical and basolateral membranes of mammary epithelial cells. In this review, we focus on transport mechanisms that contribute to the secretion of calcium, trace minerals and water soluble vitamins into milk with particular focus on the role of transporters of the SLC series as well as calcium transport proteins (ion channels and pumps). Numerous members of the SLC family are involved in the regulation of essential nutrients in the milk, such as the divalent metal transporter-1 (SLC11A2), ferroportin-1 (SLC40A1) and the copper transporter CTR1 (SLC31A1). A deeper understanding of the physiology and pathophysiology of these transporters will be of great value for drug discovery and treatment of breast diseases.
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Affiliation(s)
- Nicolas Montalbetti
- Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research, NCCR TransCure, University of Bern, Bühlstrasse 28, 3012, Bern, Switzerland,
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Yoshimatsu H, Yonezawa A, Yao Y, Sugano K, Nakagawa S, Omura T, Matsubara K. Functional involvement of RFVT3/SLC52A3 in intestinal riboflavin absorption. Am J Physiol Gastrointest Liver Physiol 2014; 306:G102-10. [PMID: 24264046 DOI: 10.1152/ajpgi.00349.2013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Riboflavin, also known as vitamin B2, is transported across the biological membrane into various organs by transport systems. Riboflavin transporter RFVT3 is expressed in the small intestine and has been suggested to localize in the apical membranes of the intestinal epithelial cells. In this study, we investigated the functional involvement of RFVT3 in riboflavin absorption using intestinal epithelial T84 cells and mouse small intestine. T84 cells expressed RFVT3 and conserved unidirectional riboflavin transport corresponding to intestinal absorption. Apical [(3)H]riboflavin uptake was pH-dependent in T84 cells. This uptake was not affected by Na(+) depletion at apical pH 6.0, although it was significantly decreased at apical pH 7.4. The [(3)H]riboflavin uptake from the apical side of T84 cells was prominently inhibited by the RFVT3 selective inhibitor methylene blue and significantly decreased by transfection of RFVT3-small-interfering RNA. In the gastrointestinal tract, RFVT3 was expressed in the jejunum and ileum. Mouse jejunal and ileal permeabilities of [(3)H]riboflavin were measured by the in situ closed-loop method and were significantly reduced by methylene blue. These results strongly suggest that RFVT3 would functionally be involved in riboflavin absorption in the apical membranes of intestinal epithelial cells.
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Affiliation(s)
- Hiroki Yoshimatsu
- Dept. of Clinical Pharmacology and Therapeutics, Kyoto Univ. Hospital, Sakyo-ku, Kyoto 606-8507, Japan.
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Said HM. Recent advances in transport of water-soluble vitamins in organs of the digestive system: a focus on the colon and the pancreas. Am J Physiol Gastrointest Liver Physiol 2013; 305:G601-10. [PMID: 23989008 PMCID: PMC3840235 DOI: 10.1152/ajpgi.00231.2013] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
This review focuses on recent advances in our understanding of the mechanisms and regulation of water-soluble vitamin (WSV) transport in the large intestine and pancreas, two important organs of the digestive system that have only recently received their fair share of attention. WSV, a group of structurally unrelated compounds, are essential for normal cell function and development and, thus, for overall health and survival of the organism. Humans cannot synthesize WSV endogenously; rather, WSV are obtained from exogenous sources via intestinal absorption. The intestine is exposed to two sources of WSV: a dietary source and a bacterial source (i.e., WSV generated by the large intestinal microbiota). Contribution of the latter source to human nutrition/health has been a subject of debate and doubt, mostly based on the absence of specialized systems for efficient uptake of WSV in the large intestine. However, recent studies utilizing a variety of human and animal colon preparations clearly demonstrate that such systems do exist in the large intestine. This has provided strong support for the idea that the microbiota-generated WSV are of nutritional value to the host, and especially to the nutritional needs of the local colonocytes and their health. In the pancreas, WSV are essential for normal metabolic activities of all its cell types and for its exocrine and endocrine functions. Significant progress has also been made in understanding the mechanisms involved in the uptake of WSV and the effect of chronic alcohol exposure on the uptake processes.
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Affiliation(s)
- Hamid M. Said
- Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California; and Department of Veterans Affairs Medical Center, Long Beach, California
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Hediger MA, Clémençon B, Burrier RE, Bruford EA. The ABCs of membrane transporters in health and disease (SLC series): introduction. Mol Aspects Med 2013; 34:95-107. [PMID: 23506860 PMCID: PMC3853582 DOI: 10.1016/j.mam.2012.12.009] [Citation(s) in RCA: 399] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Accepted: 12/18/2012] [Indexed: 01/19/2023]
Abstract
The field of transport biology has steadily grown over the past decade and is now recognized as playing an important role in manifestation and treatment of disease. The SLC (solute carrier) gene series has grown to now include 52 families and 395 transporter genes in the human genome. A list of these genes can be found at the HUGO Gene Nomenclature Committee (HGNC) website (see www.genenames.org/genefamilies/SLC). This special issue features mini-reviews for each of these SLC families written by the experts in each field. The existing online resource for solute carriers, the Bioparadigms SLC Tables (www.bioparadigms.org), has been updated and significantly extended with additional information and cross-links to other relevant databases, and the nomenclature used in this database has been validated and approved by the HGNC. In addition, the Bioparadigms SLC Tables functionality has been improved to allow easier access by the scientific community. This introduction includes: an overview of all known SLC and “non-SLC” transporter genes; a list of transporters of water soluble vitamins; a summary of recent progress in the structure determination of transporters (including GLUT1/SLC2A1); roles of transporters in human diseases and roles in drug approval and pharmaceutical perspectives.
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Affiliation(s)
- Matthias A Hediger
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland.
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Yonezawa A, Inui KI. Novel riboflavin transporter family RFVT/SLC52: identification, nomenclature, functional characterization and genetic diseases of RFVT/SLC52. Mol Aspects Med 2013; 34:693-701. [PMID: 23506902 DOI: 10.1016/j.mam.2012.07.014] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Accepted: 06/27/2012] [Indexed: 01/21/2023]
Abstract
Riboflavin, a water-soluble vitamin also known as vitamin B2, is essential for normal cellular functions. Riboflavin transporters play important roles in its homeostasis. Recently, three novel riboflavin transporters were identified, and designated as RFT1, RFT2 and RFT3. Because the RFTs did not show similarity to other SLC transporters, and RFT1 and RFT3 are similar in sequence and function, they were assigned into a new SLC family, SLC52. Subsequently, RFT1/GPR172B, RFT3/GPR172A and RFT2/C20orf54 were renamed as RFVT1/SLC52A1, RFVT2/SLC52A2 and RFVT3/SLC52A3, respectively. In this review, we summarize recent findings on the cloning, nomenclature, functional characterization and genetic diseases of RFVT1/SLC52A1, RFVT2/SLC52A2 and RFVT3/SLC52A3.
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Affiliation(s)
- Atsushi Yonezawa
- Department of Pharmacy, Kyoto University Hospital, Faculty of Medicine, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan
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Subramanian VS, Subramanya SB, Ghosal A, Said HM. Chronic alcohol feeding inhibits physiological and molecular parameters of intestinal and renal riboflavin transport. Am J Physiol Cell Physiol 2013; 305:C539-46. [PMID: 23804199 DOI: 10.1152/ajpcell.00089.2013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Vitamin B2 (riboflavin, RF) is essential for normal human health. Mammals obtain RF from exogenous sources via intestinal absorption and prevent its urinary loss by reabsorption in the kidneys. Both of these absorptive events are carrier-mediated and involve specific RF transporters (RFVTs). Chronic alcohol consumption in humans is associated with a high prevalence of RF deficiency and suboptimal levels, but little is known about the effect of chronic alcohol exposure on physiological and molecular parameters of the intestinal and renal RF transport events. We addressed these issues using rats chronically fed an alcohol liquid diet and pair-fed controls as a model. The results showed that chronic alcohol feeding significantly inhibits carrier-mediated RF transport across the intestinal brush-border and basolateral membrane domains of the polarized enterocytes. This inhibition was associated with a parallel reduction in the expression of the rat RFVT-1 and -3 at the protein, mRNA, and heterogeneous nuclear RNA (hnRNA) levels. Chronic alcohol feeding also caused a significant inhibition in RF uptake in the colon. Similarly, a significant inhibition in carrier-mediated RF transport across the renal brush-border and basolateral membrane domains was observed, which again was associated with a significant reduction in the level of expression of RFVT-1 and -3 at the protein, mRNA, and hnRNA levels. These findings demonstrate that chronic alcohol exposure impairs both intestinal absorption and renal reabsorption processes of RF and that these effects are, at least in part, mediated via transcriptional mechanism(s) involving the slc52a1 and slc52a3 genes.
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Affiliation(s)
- Veedamali S Subramanian
- Department of Medicine and Physiology/Biophysics, University of California, Irvine, California, USA
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Subramanian VS, Ghosal A, Subramanya SB, Lytle C, Said HM. Differentiation-dependent regulation of intestinal vitamin B(2) uptake: studies utilizing human-derived intestinal epithelial Caco-2 cells and native rat intestine. Am J Physiol Gastrointest Liver Physiol 2013; 304:G741-8. [PMID: 23413253 PMCID: PMC3625875 DOI: 10.1152/ajpgi.00018.2013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Intestinal epithelial cells undergo differentiation as they move from the crypt to the villi, a process that is associated with up- and downregulation in expression of a variety of genes, including those involved in nutrient absorption. Whether the intestinal uptake process of vitamin B(2) [riboflavin (RF)] also undergoes differentiation-dependent regulation and the mechanism through which this occurs are not known. We used human-derived intestinal epithelial Caco-2 cells and native rat intestine as models to address these issues. Caco-2 cells showed a significantly higher carrier-mediated RF uptake in post- than preconfluent cells. This upregulation was associated with a significantly higher level of protein and mRNA expression of the RF transporters hRFVT-1 and hRFVT-3 in the post- than preconfluent cells; it was also accompanied with a significantly higher rate of transcription of the respective genes (SLC52A1 and SLC52A3), as indicated by the higher level of expression of heterogeneous nuclear RNA and higher promoter activity in post- than preconfluent cells. Studies with native rat intestine also showed a significantly higher RF uptake by epithelial cells of the villus tip than epithelial cells of the crypt; this again was accompanied by a significantly higher level of expression of the rat RFVT-1 and RFVT-3 at the protein, mRNA, and heterogeneous nuclear RNA levels. These findings show, for the first time, that the intestinal RF uptake process undergoes differentiation-dependent upregulation and suggest that this is mediated (at least in part) via transcriptional mechanisms.
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Affiliation(s)
- Veedamali S. Subramanian
- 1Departments of Medicine, Physiology, and Biophysics, University of California, Irvine, California; ,2Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California; and
| | - Abhisek Ghosal
- 1Departments of Medicine, Physiology, and Biophysics, University of California, Irvine, California; ,2Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California; and
| | - Sandeep B. Subramanya
- 1Departments of Medicine, Physiology, and Biophysics, University of California, Irvine, California; ,2Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California; and
| | - Christian Lytle
- 3Division of Biomedical Sciences, University of California, Riverside, California
| | - Hamid M. Said
- 1Departments of Medicine, Physiology, and Biophysics, University of California, Irvine, California; ,2Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California; and
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Abstract
The eye is a highly protected organ, and designing an effective therapy is often considered a challenging task. The anatomical and physiological barriers result in low ocular bioavailability of drugs. Due to these constraints, less than 5% of the administered dose is absorbed from the conventional ophthalmic dosage forms. Further, physicochemical properties such as lipophilicity, molecular weight and charge modulate the permeability of drug molecules. Vision-threatening diseases such as glaucoma, diabetic macular edema, cataract, wet and dry age-related macular degeneration, proliferative vitreoretinopathy, uveitis, and cytomegalovirus retinitis alter the pathophysiological and molecular mechanisms. Understanding these mechanisms may result in the development of novel treatment modalities. Recently, transporter/receptor targeted prodrug approach has generated significant interest in ocular drug delivery. These transporters and receptors are involved in the transport of essential nutrients, vitamins, and xenobiotics across biological membranes. Several influx transporters (peptides, amino acids, glucose, lactate and nucleosides/nucleobases) and receptors (folate and biotin) have been identified on conjunctiva, cornea, and retina. Structural and functional delineation of these transporters will enable more drugs targeting the posterior segment to be successfully delivered topically. Prodrug derivatization targeting transporters and receptors expressed on ocular tissues has been the subject of intense research. Several prodrugs have been designed to target these transporters and enhance the absorption of poorly permeating parent drug. Moreover, this approach might be used in gene delivery to modify cellular function and membrane receptors. This review provides comprehensive information on ocular drug delivery, with special emphasis on the use of transporters and receptors to improve drug bioavailability.
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Biswas A, Elmatari D, Rothman J, LaMunyon CW, Said HM. Identification and functional characterization of the Caenorhabditis elegans riboflavin transporters rft-1 and rft-2. PLoS One 2013; 8:e58190. [PMID: 23483992 PMCID: PMC3590142 DOI: 10.1371/journal.pone.0058190] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Accepted: 01/31/2013] [Indexed: 02/07/2023] Open
Abstract
Two potential orthologs of the human riboflavin transporter 3 (hRFVT3) were identified in the C. elegans genome, Y47D7A.16 and Y47D7A.14, which share 33.7 and 30.5% identity, respectively, with hRFVT3. The genes are tandemly arranged, and we assign them the names rft-1 (for Y47D7A.16) and rft-2 (for Y47D7A.14). Functional characterization of the coding sequences in a heterologous expression system demonstrated that both were specific riboflavin transporters, although the rft-1 encoded protein had greater transport activity. A more detailed examination of rft-1 showed its transport of riboflavin to have an acidic pH dependence, saturability (apparent Km = 1.4 ± 0.5 µM), inhibition by riboflavin analogues, and Na(+) independence. The expression of rft-1 mRNA was relatively higher in young larvae than in adults, and mRNA expression dropped in response to RF supplementation. Knocking down the two transporters individually via RNA interference resulted in a severe loss of fertility that was compounded in a double knockdown. Transcriptional fusions constructed with two fluorophores (rft-1::GFP, and rft-2::mCherry) indicated that rft-1 is expressed in the intestine and a small subset of neuronal support cells along the entire length of the animal. Expression of rft-2 is localized mainly to the intestine and pharynx. We also observed a drop in the expression of the two reporters in animals that were maintained in high riboflavin levels. These results report for the first time the identification of two riboflavin transporters in C. elegans and demonstrate their expression and importance to metabolic function in worms. Absence of transporter function renders worms sterile, making them useful in understanding human disease associated with mutations in hRFVT3.
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Affiliation(s)
- Arundhati Biswas
- Departments of Medicine and Physiology/Biophysics, University of California Medical School, Irvine, California, United States of America
- Veterans Affairs Medical Center, Long Beach, California, United States of America
| | - Daniel Elmatari
- Department of Biological Sciences, California State Polytechnic University, Pomona, California, United States of America
| | - Jason Rothman
- Department of Biological Sciences, California State Polytechnic University, Pomona, California, United States of America
| | - Craig W. LaMunyon
- Department of Biological Sciences, California State Polytechnic University, Pomona, California, United States of America
| | - Hamid M. Said
- Departments of Medicine and Physiology/Biophysics, University of California Medical School, Irvine, California, United States of America
- Veterans Affairs Medical Center, Long Beach, California, United States of America
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Nabokina SM, Subramanian VS, Said HM. Effect of clinical mutations on functionality of the human riboflavin transporter-2 (hRFT-2). Mol Genet Metab 2012; 105:652-7. [PMID: 22273710 PMCID: PMC3309148 DOI: 10.1016/j.ymgme.2011.12.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Revised: 12/27/2011] [Accepted: 12/27/2011] [Indexed: 10/14/2022]
Abstract
The Brown-Vialetto-Van Laere syndrome (BVVLS) is a rare neurological disease characterized by ponto-bulbar palsy, bilateral sensorineural deafness, and respiratory insufficiency. Recent genetic studies have identified mutations in the C20orf54 gene, which encodes the human riboflavin (RF) transporter -2 (hRFT-2) and suggested their link to the manifestation of BVVLS. However, there is nothing currently known about the effect of these mutations on functionality of hRFT-2, a protein that is expressed in a variety of tissues with high expression in the intestine. We addressed this issue using the human-derived intestinal epithelial Caco-2 cells. Our results showed significant (P<0.01) impairment in RF uptake by Caco-2 cells transiently expressing W17R, P28T, E36K, E71K, and R132W (but not L350M) hRFT-2 mutants. This impairment in RF transport was not due to a decrease in transcription and/or translation of hRFT-2, since mRNA and protein levels of the carrier were similar in cells expressing the mutants and wild-type hRFT-2. Confocal images of live Caco-2 cells transiently transfected with hRFT-2 mutants (fused with green fluorescent protein) showed the P28T, E36K, E71K, and R132W mutants were retained within the endoplasmic reticulum, while the W17R and L350M mutants were expressed at the cell membrane; cell surface expression of the W17R mutant was further confirmed by direct determination of cell surface transporter density. These results show for the first time that some of the BVVLS associated mutations in hRFT-2 affect the transporter functionality and that this effect is mediated via alterations in membrane targeting and/or activity of the transporter.
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Affiliation(s)
- Svetlana M Nabokina
- Departments of Medicine, Physiology/Biophysics, University of California, Irvine, CA 92697, USA
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