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Butts M, Sundaram VL, Murughiyan U, Borthakur A, Singh S. The Influence of Alcohol Consumption on Intestinal Nutrient Absorption: A Comprehensive Review. Nutrients 2023; 15:nu15071571. [PMID: 37049411 PMCID: PMC10096942 DOI: 10.3390/nu15071571] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 03/18/2023] [Accepted: 03/22/2023] [Indexed: 04/14/2023] Open
Abstract
Chronic alcohol use has been attributed to the development of malnutrition. This is in part due to the inhibitory effect of ethanol on the absorption of vital nutrients, including glucose, amino acids, lipids, water, vitamins, and minerals within the small intestine. Recent advances in research, along with new cutting-edge technologies, have advanced our understanding of the mechanism of ethanol's effect on intestinal nutrient absorption at the brush border membrane (BBM) of the small intestine. However, further studies are needed to delineate how ethanol consumption could have an impact on altered nutrient absorption under various disease conditions. Current research has elucidated the relationship of alcohol consumption on glucose, glutamine, vitamins B1 (thiamine), B2 (riboflavin), B9 (folate), C (ascorbic acid), selenium, iron, and zinc absorption within the small intestine. We conducted systematic computerized searches in PubMed using the following keywords: (1) "Alcohol effects on nutrient transport"; (2) "Alcohol mediated malabsorption of nutrients"; (3) "Alcohol effects on small intestinal nutrient transport"; and (4) "Alcohol mediated malabsorption of nutrients in small intestine". We included the relevant studies in this review. The main objective of this review is to marshal and analyze previously published research articles and discuss, in-depth, the understanding of ethanol's effect in modulating absorption of vital macro and micronutrients in health and disease conditions. This could ultimately provide great insights in the development of new therapeutic strategies to combat malnutrition associated with alcohol consumption.
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Affiliation(s)
- Molly Butts
- Department of Clinical and Translational Sciences, Marshall University, Huntington, WV 25755, USA
| | - Vijaya Lakshmi Sundaram
- Department of Clinical and Translational Sciences, Marshall University, Huntington, WV 25755, USA
| | - Usha Murughiyan
- Department of Clinical and Translational Sciences, Marshall University, Huntington, WV 25755, USA
| | - Alip Borthakur
- Department of Clinical and Translational Sciences, Marshall University, Huntington, WV 25755, USA
| | - Soudamani Singh
- Department of Clinical and Translational Sciences, Marshall University, Huntington, WV 25755, USA
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Tsuji A, Ikeda Y, Murakami M, Kitagishi Y, Matsuda S. Reduction of oocyte lipid droplets and meiotic failure due to biotin deficiency was not rescued by restoring the biotin nutritional status. Nutr Res Pract 2022; 16:314-329. [PMID: 35663441 PMCID: PMC9149319 DOI: 10.4162/nrp.2022.16.3.314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 06/29/2021] [Accepted: 09/09/2021] [Indexed: 11/04/2022] Open
Affiliation(s)
- Ai Tsuji
- Department of Food Science and Nutrition, Faculty of Human Life and Environment, Nara Women's University, Nara 630-8506, Japan
| | - Yuka Ikeda
- Department of Food Science and Nutrition, Faculty of Human Life and Environment, Nara Women's University, Nara 630-8506, Japan
| | - Mutsumi Murakami
- Department of Food Science and Nutrition, Faculty of Human Life and Environment, Nara Women's University, Nara 630-8506, Japan
| | - Yasuko Kitagishi
- Department of Food Science and Nutrition, Faculty of Human Life and Environment, Nara Women's University, Nara 630-8506, Japan
| | - Satoru Matsuda
- Department of Food Science and Nutrition, Faculty of Human Life and Environment, Nara Women's University, Nara 630-8506, Japan
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Ramamoorthy K, Sabui S, Srinivasan P, Al-Juburi S, Pham Q, Chu BD, Simoes RD, Fleckenstein JM, Said HM. Effect of chronic alcohol exposure on gut vitamin B7 uptake: involvement of epigenetic mechanisms and effect of alcohol metabolites. Am J Physiol Gastrointest Liver Physiol 2021; 321:G123-G133. [PMID: 34077272 PMCID: PMC8410103 DOI: 10.1152/ajpgi.00144.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Vitamin B7 (biotin) is essential for normal health and its deficiency/suboptimal levels occur in a variety of conditions including chronic alcoholism. Mammals, including humans, obtain biotin from diet and gut-microbiota via absorption along the intestinal tract. The absorption process is carrier mediated and involves the sodium-dependent multivitamin transporter (SMVT; SLC5A6). We have previously shown that chronic alcohol exposure significantly inhibits intestinal/colonic biotin uptake via suppression of Slc5a6 transcription in animal and cell line models. However, little is known about the transcriptional/epigenetic factors that mediate this suppression. In addition, the effect of alcohol metabolites (generated via alcohol metabolism by gut microbiota and host tissues) on biotin uptake is still unknown. To address these questions, we first demonstrated that chronic alcohol exposure inhibits small intestinal and colonic biotin uptake and SMVT expression in human differentiated enteroid and colonoid monolayers. We then showed that chronic alcohol exposures of both, Caco-2 cells and mice, are associated with a significant suppression in expression of the nuclear factor KLF-4 (needed for Slc5a6 promoter activity), as well as with epigenetic alterations (histone modifications). We also found that chronic exposure of NCM460 human colonic epithelial cells as well as human differentiated colonoid monolayers, to alcohol metabolites (acetaldehyde, ethyl palmitate, ethyl oleate) significantly inhibited biotin uptake and SMVT expression. These findings shed light onto the molecular/epigenetic mechanisms that mediate the inhibitory effect of chronic alcohol exposure on intestinal biotin uptake. They further show that alcohol metabolites are also capable of inhibiting biotin uptake in the gut.NEW & NOTEWORTHY Using complementary models, including human differentiated enteroid and colonoid monolayers, this study shows the involvement of molecular and epigenetic mechanisms in mediating the inhibitory effect of chronic alcohol exposure on biotin uptake along the intestinal tract. The study also shows that alcohol metabolites (generated by gut microbiota and host tissues) cause inhibition in gut biotin uptake.
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Affiliation(s)
- Kalidas Ramamoorthy
- 1Department of Physiology/Biophysics, University of California, Irvine, California
| | - Subrata Sabui
- 1Department of Physiology/Biophysics, University of California, Irvine, California,5Veterans Affairs Medical Center, Long Beach, California
| | - Padmanabhan Srinivasan
- 1Department of Physiology/Biophysics, University of California, Irvine, California,5Veterans Affairs Medical Center, Long Beach, California
| | - Saleh Al-Juburi
- 1Department of Physiology/Biophysics, University of California, Irvine, California
| | - Quang Pham
- 1Department of Physiology/Biophysics, University of California, Irvine, California
| | - Brian D. Chu
- 1Department of Physiology/Biophysics, University of California, Irvine, California,5Veterans Affairs Medical Center, Long Beach, California
| | - Rita D. Simoes
- 3Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri
| | - James M. Fleckenstein
- 3Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri,4Veterans Affairs Medical Center, St. Louis Missouri
| | - Hamid M. Said
- 1Department of Physiology/Biophysics, University of California, Irvine, California,2Department of Medicine, University of California, Irvine, California,5Veterans Affairs Medical Center, Long Beach, California
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4
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Yang J, Wiencek JR. Mitigating biotin interference in two Roche immunoassays by premixing biotinylated capturing molecules with streptavidin coated beads. Clin Chim Acta 2020; 505:130-135. [PMID: 32084383 DOI: 10.1016/j.cca.2020.02.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Revised: 01/31/2020] [Accepted: 02/17/2020] [Indexed: 11/24/2022]
Abstract
BACKGROUND Biotin is an interference in many streptavidin-biotin based immunoassays, causing falsely decreased results with sandwich immunoassays and falsely increased results with competitive immunoassays. It has been discussed that premixing streptavidin coated beads and biotinylated capturing molecules may prevent biotin interference. This study was designed to test whether such modification could mitigate biotin interference in two originally susceptible sandwich immunoassays. METHODS Roche C-peptide and human growth hormone (hGH) immunoassays utilize three reagent containers for streptavidin coated beads (M), biotinylated capturing antibody (R1) and ruthenylated antibody (R2). The reagents were modified by premixing reagent M and R1. Following incubation, the beads were placed back in the M-container and R1-supernatant back to R1-container. Patient specimens were selected, spiked with biotin to 1055 ng/mL, and measured by both the original, unmodified reagent and modified reagent on Roche cobas e411 analyzer. The biotin interference dose response curves were also compared using pooled patient specimen spiked with different concentrations of biotin. RESULTS For the original reagent, 1055 ng/mL of biotin decreased C- peptide results by 88% and hGH results by 97%. After reagent modification, this interference effect was nearly eliminated for C- peptide but remained about 20% decreased for hGH. CONCLUSION Premixing streptavidin beads and biotinylated capturing molecules is an effective approach to mitigate biotin interference for certain immunoassays.
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Affiliation(s)
- Jianbo Yang
- Medical Laboratories, University of Virginia Health, Charlottesville, VA, United States
| | - Joesph R Wiencek
- Department of Pathology, University of Virginia School of Medicine, Charlottesville, VA, United States.
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5
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Skupsky J, Sabui S, Hwang M, Nakasaki M, Cahalan MD, Said HM. Biotin Supplementation Ameliorates Murine Colitis by Preventing NF-κB Activation. Cell Mol Gastroenterol Hepatol 2019; 9:557-567. [PMID: 31786364 PMCID: PMC7078531 DOI: 10.1016/j.jcmgh.2019.11.011] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 11/21/2019] [Accepted: 11/21/2019] [Indexed: 12/13/2022]
Abstract
BACKGROUND & AIMS Biotin is a water-soluble vitamin that is indispensable for human health. Biotin deficiency can cause failure-to-thrive, immunodeficiency, alopecia, dermatitis, and conjunctivitis. We previously reported that biotin deficiency also can lead to severe colitis in mice, which is completely reversed with supplementation. Our aim in this study was to determine if high-dose biotin supplementation can provide a therapeutic benefit in a preclinical model for inflammatory bowel disease (IBD) and to identify the molecular mechanism by which this occurs. METHODS Mice were challenged with dextran sodium sulfate to induce colitis and were treated with 1 mmol/L biotin to induce or maintain remission. Clinical response was monitored by the Disease Activity Index and fecal calprotectin levels. The colon tissue was investigated for histology, length, as well as expression of inflammatory cytokines (interleukin 6, tumor necrosis factor-α, interleukin 1β), intestinal permeability, tight junctions (zonula occludens-1 and claudin-2), and the transcription factor nuclear factor-κB (NF-κB). RESULTS Biotin therapy led to delayed onset and severity of colitis as well as accelerated healing. There was improvement in the Disease Activity Index, fecal calprotectin levels, colon length, and histology. In addition, biotin-treated mice had reduced expression of inflammatory cytokines, reduced intestinal permeability, and reduced activation of NF-κB. CONCLUSIONS Oral supplementation with biotin provides benefit for maintenance and induction of remission in the dextran sodium sulfate preclinical model for IBD. Biotin does this by reducing the activation of NF-κB, which prevents the production of inflammatory cytokines and helps maintain the integrity of the intestinal barrier. Clinically, the NF-κB pathway is important in the development of IBD and this finding suggests that biotin may have therapeutic potential for patients with IBD.
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Affiliation(s)
- Jonathan Skupsky
- Department of Medicine, Division of Gastroenterology, Veterans Affairs Long Beach, Long Beach, California,Department of Medicine, Gastroenterology, University of California Irvine, Irvine, California,Correspondence Address correspondence to: Jonathan Skupsky, MD, PhD, Department of Medicine, Gastroenterology, University of California Irvine, 285 Irvine Hall, Irvine, California 92697. fax: (949) 824-8540.
| | - Subrata Sabui
- Department of Medical Research, Veterans Affairs Long Beach, Long Beach, California,Department of Physiology and Biophysics, University of California Irvine, Irvine, California
| | - Michael Hwang
- Department of Medical Research, Veterans Affairs Long Beach, Long Beach, California,Department of Medicine, University of California Irvine, Irvine, California
| | - Manando Nakasaki
- Department of Pathology, University of California Irvine, Irvine, California
| | - Michael D. Cahalan
- Department of Physiology and Biophysics, University of California Irvine, Irvine, California
| | - Hamid M. Said
- Department of Medical Research, Veterans Affairs Long Beach, Long Beach, California,Department of Physiology and Biophysics, University of California Irvine, Irvine, California,Department of Medicine, University of California Irvine, Irvine, California
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Abdel-Magied N, Shedid SM, Ahmed AG. Mitigating effect of biotin against irradiation-induced cerebral cortical and hippocampal damage in the rat brain tissue. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:13441-13452. [PMID: 30911963 DOI: 10.1007/s11356-019-04806-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 03/06/2019] [Indexed: 06/09/2023]
Abstract
Radiation-induced brain injury is common and mainly occurs in patients receiving radiotherapy for malignant head and neck tumors. The brain is oversensitive to oxidant injury induced by radiation. Biotin is a member of the vitamin B complex family and its deficiency has been associated with neurogenesis impairment in animals and humans. The present study was undertaken to investigate the mitigating effect of biotin on the cerebral cortical and hippocampal damage induced by radiation exposure. Animals were exposed to radiation in the presence or absence of biotin and sacrificed on day 10. The results demonstrated that the administration of biotin 2 mg to irradiated rats had no significant effect on the radiation-induced damage of the cerebral cortex and the hippocampus, while the administration of biotin 6 mg has significantly attenuated oxidative stress in the hippocampus, manifested by a reduction of 4-hydroxynonenal (4HNE), total nitrate/nitrite (NOx), and xanthine oxidase (XO) levels associated with an elevation of glutathione (GSH) content as well as superoxide dismutase (SOD) and catalase (CAT) activities. In addition, biotin decreased the pro-inflammatory cytokines (interleukin-1 beta (IL-1β), interleukin-6 (IL-6), and tumor necrotic factor alpha (TNF-α)), caspase-3, poly(ADP-ribose) polymerase 1 (PARP1) level, and PARP1 gene expression. Moreover, biotin 6 mg treatment diminished serum S100 protein (S100B) and neuron-specific enolase (NSE) levels. In conclusion, biotin treatment at high dose post-irradiation has efficiently neutralized the effect of free radicals in the hippocampal region of rats. Thus, it could be applicable as a radio-mitigator for reducing or delayed radiation-induced brain injury in patients post-radiotherapy.
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Affiliation(s)
- Nadia Abdel-Magied
- Radiation Biology Research Department, National Centre for Radiation Research and Technology (NCRRT), Atomic Energy Authority (AEA), 3 street (3st) Ahmed Elzomer, P.O. Box 29, Nasr City, Cairo, Egypt.
| | - Shereen M Shedid
- Radiation Biology Research Department, National Centre for Radiation Research and Technology (NCRRT), Atomic Energy Authority (AEA), 3 street (3st) Ahmed Elzomer, P.O. Box 29, Nasr City, Cairo, Egypt
| | - Amal G Ahmed
- Radiation Biology Research Department, National Centre for Radiation Research and Technology (NCRRT), Atomic Energy Authority (AEA), 3 street (3st) Ahmed Elzomer, P.O. Box 29, Nasr City, Cairo, Egypt
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Ciocan D, Voican CS, Wrzosek L, Hugot C, Rainteau D, Humbert L, Cassard AM, Perlemuter G. Bile acid homeostasis and intestinal dysbiosis in alcoholic hepatitis. Aliment Pharmacol Ther 2018; 48:961-974. [PMID: 30144108 DOI: 10.1111/apt.14949] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 04/25/2018] [Accepted: 07/27/2018] [Indexed: 12/20/2022]
Abstract
BACKGROUND Intestinal microbiota plays an important role in bile acid homeostasis. AIM To study the structure of the intestinal microbiota and its function in bile acid homeostasis in alcoholic patients based on the severity of alcoholic liver disease. METHODS In this prospective study, we included four groups of active alcoholic patients (N = 108): two noncirrhotic, with (noCir_AH, n = 13) or without alcoholic hepatitis (noCir_noAH, n = 61), and two cirrhotic, with (Cir_sAH, n = 17) or without severe alcoholic hepatitis (Cir_noAH, n = 17). Plasma and faecal bile acid profiles and intestinal microbiota composition were assessed. RESULTS Plasma levels of total bile acids (84.6 vs 6.8 μmol/L, P < 0.001) and total ursodeoxycholic acid (1.3 vs 0.3 μmol/L, P = 0.03) were higher in cirrhosis with severe alcoholic hepatitis (Cir_sAH) than Cir_noAH, whereas total faecal (2.4 vs 11.3, P = 0.01) and secondary bile acids (0.7 vs 10.7, P < 0.01) levels were lower. Cir_sAH patients had a different microbiota than Cir_noAH patients: at the phyla level, the abundance of Actinobacteria (9 vs 1%, P = 0.01) was higher and that of Bacteroidetes was lower (25 vs 40%, P = 0.04). Moreover, the microbiota of Cir_sAH patients showed changes in the abundance of genes involved in 15 metabolic pathways, including upregulation of glutathione metabolism, and downregulation of biotin metabolism. CONCLUSIONS Patients with Cir_sAH show specific changes of the bile acid pool with a shift towards more hydrophobic and toxic species that may be responsible for the specific microbiota changes. Conversely, the microbiota may also alter the bile acid pool by transforming primary to secondary bile acids, leading to a vicious cycle.
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Affiliation(s)
- Dragos Ciocan
- Inflammation Chimiokines et Immunopathologie, DHU Hepatinov, Faculté de Médecine-Université Paris-Sud/Université Paris-Saclay, INSERM, UMR-S 996, Clamart, France
| | - Cosmin Sebastian Voican
- Inflammation Chimiokines et Immunopathologie, DHU Hepatinov, Faculté de Médecine-Université Paris-Sud/Université Paris-Saclay, INSERM, UMR-S 996, Clamart, France.,AP-HP, Hepatogastroenterology and Nutrition, Hôpital Antoine-Béclère, Clamart, France
| | - Laura Wrzosek
- Inflammation Chimiokines et Immunopathologie, DHU Hepatinov, Faculté de Médecine-Université Paris-Sud/Université Paris-Saclay, INSERM, UMR-S 996, Clamart, France.,AP-HP, Hepatogastroenterology and Nutrition, Hôpital Antoine-Béclère, Clamart, France
| | - Cindy Hugot
- Inflammation Chimiokines et Immunopathologie, DHU Hepatinov, Faculté de Médecine-Université Paris-Sud/Université Paris-Saclay, INSERM, UMR-S 996, Clamart, France
| | - Dominique Rainteau
- UPMC Université Paris 6, Sorbonne Universités, Paris, France.,Inflammation-Immunopathology-Biotherapy Department (DHU i2B), INSERM-ERL 1157, Paris, France.,UMR 7203, Laboratoire des Biomolécules, UPMC/CNRS/ENS, Paris, France.,Département PM2 Plateforme de Métabolomique, APHP, Hôpital Saint Antoine, Peptidomique et dosage de Médicaments, Paris, France
| | - Lydie Humbert
- UPMC Université Paris 6, Sorbonne Universités, Paris, France.,Inflammation-Immunopathology-Biotherapy Department (DHU i2B), INSERM-ERL 1157, Paris, France.,UMR 7203, Laboratoire des Biomolécules, UPMC/CNRS/ENS, Paris, France
| | - Anne-Marie Cassard
- Inflammation Chimiokines et Immunopathologie, DHU Hepatinov, Faculté de Médecine-Université Paris-Sud/Université Paris-Saclay, INSERM, UMR-S 996, Clamart, France
| | - Gabriel Perlemuter
- Inflammation Chimiokines et Immunopathologie, DHU Hepatinov, Faculté de Médecine-Université Paris-Sud/Université Paris-Saclay, INSERM, UMR-S 996, Clamart, France.,AP-HP, Hepatogastroenterology and Nutrition, Hôpital Antoine-Béclère, Clamart, France
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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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Abstract
Biotin is a coenzyme for carboxylase enzymes that assist various metabolic reactions involved in fatty acid synthesis, branched-chain amino acid catabolism, and gluconeogenesis important for maintenance of healthy skin and hair. Due to its availability, affordability, and effective marketing for this purpose, biotin is a popular nutritional supplement for treatment of hair loss. However, there are little data on the frequency of biotin deficiency in patients complaining of hair loss and on the value of oral biotin for treatment of hair loss that is not due to an inborn error of biotin metabolism or deficiency. The aim of this study was to determine the frequency and significance of biotin deficiency in women complaining of hair loss. Biotin deficiency was found in 38% of women complaining of hair loss. Of those showing diffuse telogen effluvium in trichograms (24%), 35% had evidence of associated seborrheic-like dermatitis. About 11% of patients with biotin deficiency had a positive personal history for risk factors for biotin deficiency. The custom of treating women complaining of hair loss in an indiscriminate manner with oral biotin supplementation is to be rejected, unless biotin deficiency and its significance for the complaint of hair loss in an individual has been demonstrated on the basis of a careful patient history, clinical examination, determination of serum biotin levels, and exclusion of alternative factors responsible for hair loss.
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Affiliation(s)
- Ralph M Trüeb
- Center for Dermatology and Hair Diseases Professor Trüeb, Zurich-Wallisellen, Switzerland
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10
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Sharma B, Dabur R. Protective Effects ofTinospora cordifoliaon Hepatic and Gastrointestinal Toxicity Induced by Chronic and Moderate Alcoholism. Alcohol Alcohol 2015; 51:1-10. [DOI: 10.1093/alcalc/agv130] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Accepted: 10/26/2015] [Indexed: 12/16/2022] Open
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Srinivasan P, Nabokina S, Said HM. Chronic alcohol exposure affects pancreatic acinar mitochondrial thiamin pyrophosphate uptake: studies with mouse 266-6 cell line and primary cells. Am J Physiol Gastrointest Liver Physiol 2015; 309:G750-8. [PMID: 26316591 PMCID: PMC4628969 DOI: 10.1152/ajpgi.00226.2015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 08/21/2015] [Indexed: 01/31/2023]
Abstract
Thiamin is essential for normal metabolic activity of all mammalian cells, including those of the pancreas. Cells obtain thiamin from their surroundings and enzymatically convert it into thiamin pyrophosphate (TPP) in the cytoplasm; TPP is then taken up by mitochondria via a specific carrier the mitochondrial TPP transporter (MTPPT; product of the SLC25A19 gene). Chronic alcohol exposure negatively impacts the health of pancreatic acinar cells (PAC), but its effect on physiological/molecular parameters of MTPPT is not known. We addressed this issue using mouse pancreatic acinar tumor cell line 266-6 and primary PAC of wild-type and transgenic mice carrying the SLC25A19 promoter that were fed alcohol chronically. Chronic alcohol exposure of 266-6 cells (but not to its nonoxidative metabolites ethyl palmitate and ethyl oleate) led to a significant inhibition in mitochondrial TPP uptake, which was associated with a decreased expression of MTPPT protein, mRNA, and activity of the SLC25A19 promoter. Similarly, chronic alcohol feeding of mice led to a significant inhibition in expression of MTPPT protein, mRNA, heterogeneous nuclear RNA, as well as in activity of SLC25A19 promoter in PAC. While chronic alcohol exposure did not affect DNA methylation of the Slc25a19 promoter, a significant decrease in histone H3 euchromatin markers and an increase in H3 heterochromatin marker were observed. These findings show, for the first time, that chronic alcohol exposure negatively impacts pancreatic MTPPT, and that this effect is exerted, at least in part, at the level of Slc25a19 transcription and appears to involve epigenetic mechanism(s).
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Affiliation(s)
- Padmanabhan Srinivasan
- Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California; and Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California
| | - Svetlana Nabokina
- Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California; and Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California
| | - Hamid M. Said
- Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California; and Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California
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Thakur S, Rahat B, More D, Kaur J. Reduced SP1-mediated transcriptional activation decreases expression of intestinal folate transporters in response to ethanol exposure. Mol Nutr Food Res 2015; 59:1713-24. [PMID: 26012520 DOI: 10.1002/mnfr.201400874] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 04/23/2015] [Accepted: 04/27/2015] [Indexed: 12/16/2023]
Abstract
SCOPE The study was designed to identify the regulatory mechanisms underlying the effects of ethanol exposure on intestinal folate transport and to investigate the reversibility of such effects. METHODS AND RESULTS Caco-2 cells were grown in control and ethanol containing medium for 96 h. Thereafter, one subgroup of cells was shifted on ethanol free medium and grown for next 72 h. For in vivo studies, rats were given 1g ethanol/kg body weight/day either for 3 or 5 months and after 3 months of ethanol treatment, one group of rats received no ethanol for 2 months. A significant decrease in folic acid transport as well as expression of folate transporters was observed on ethanol treatment and the effects were reversible upon removal of ethanol. Ethanol exposure had no impact on CpG island methylation of the folate transporters however, an increase in their mRNA half-life was observed that seems to be a homeostatic mechanism. Chromatin immunoprecipitation assay revealed a decrease in binding of SP1 transcription factor to the promoter regions of folate transporters. CONCLUSION Reduced binding of SP1 to the promoter region of folate transporters may be a part of the regulatory mechanism resulting in decreased expression of folate transporters on ethanol exposure.
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Affiliation(s)
- Shilpa Thakur
- Department of Biochemistry, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Beenish Rahat
- Department of Biochemistry, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Deepti More
- Department of Biochemistry, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Jyotdeep Kaur
- Department of Biochemistry, Postgraduate Institute of Medical Education and Research, Chandigarh, India
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Srinivasan P, Kapadia R, Biswas A, Said HM. Chronic alcohol exposure inhibits biotin uptake by pancreatic acinar cells: possible involvement of epigenetic mechanisms. Am J Physiol Gastrointest Liver Physiol 2014; 307:G941-9. [PMID: 25214397 PMCID: PMC4250263 DOI: 10.1152/ajpgi.00278.2014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 09/04/2014] [Indexed: 01/31/2023]
Abstract
Chronic exposure to alcohol affects different physiological aspects of pancreatic acinar cells (PAC), but its effect on the uptake process of biotin is not known. We addressed this issue using mouse-derived pancreatic acinar 266-6 cells chronically exposed to alcohol and wild-type and transgenic mice (carrying the human SLC5A6 5'-promoter) fed alcohol chronically. First we established that biotin uptake by PAC is Na(+) dependent and carrier mediated and involves sodium-dependent multivitamin transporter (SMVT). Chronic exposure of 266-6 cells to alcohol led to a significant inhibition in biotin uptake, expression of SMVT protein, and mRNA as well as in the activity of the SLC5A6 promoter. Similarly, chronic alcohol feeding of wild-type and transgenic mice carrying the SLC5A6 promoter led to a significant inhibition in biotin uptake by PAC, as well as in the expression of SMVT protein and mRNA and the activity of the SLC5A6 promoters expressed in the transgenic mice. We also found that chronic alcohol feeding of mice is associated with a significant increase in the methylation status of CpG islands predicted to be in the mouse Slc5a6 promoters and a decrease in the level of expression of transcription factor KLF-4, which plays an important role in regulating SLC5A6 promoter activity. These results demonstrate, for the first time, that chronic alcohol exposure negatively impacts biotin uptake in PAC and that this effect is exerted (at least in part) at the level of transcription of the SLC5A6 gene and may involve epigenetic/molecular mechanisms.
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Affiliation(s)
- Padmanabhan Srinivasan
- Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California; and Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California
| | - Rubina Kapadia
- Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California; and Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California
| | - Arundhati Biswas
- Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California; and Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California
| | - Hamid M Said
- Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California; and Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California
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Fahmy N, Woo M, Alameldin M, Lee JK, MacDonald K, Goneau LW, Cadieux P, Burton J, Pautler S. Endogenous biotin expression in renal and testicular tumours and literature review. Can Urol Assoc J 2014; 8:268-72. [PMID: 25210551 DOI: 10.5489/cuaj.1810] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
INTRODUCTION The aim of this study was to examine endogenous biotin levels in tumour specimens collected from patients with renal and testicular tumours and compare them to the surrounding non-neoplastic surgical margin. METHODS Frozen samples were obtained from the Ontario Tumour Bank. Renal and testicular tumour tissue were included in this study. Normal tissue from the negative surgical margins of each tumour served as a control. Biotin detection in tissue specimens was determined using immunohistochemistry (IHC). RESULTS Specimens collected from 56 patients (36 men and 20 women) were included in this study. Histopathology of the 52 renal tumours included 31 (60%) conventional type RCC, 5 (10%) chromophobe RCC, 5 (10%) papillary RCC, 1 (2%) oncocytoma and 10 (19%) upper tract urothelial carcinoma (UC). The 4 testicular tumours included 1 seminomatous (25%) germ cell tumour and 3 (75%) non seminomatous germ cell tumours. CONCLUSION No biotin signal was perceived in all tested tumour samples. Endogenous biotin expression was detected in the matching non-neoplastic surgical margin of tested renal tissues. This lack of staining may prove to be a valuable tool in future studies.
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Affiliation(s)
- Nader Fahmy
- Division of Urology, Department of Surgery, Western University, London ON
| | - Mark Woo
- Division of Urology, Department of Surgery, Western University, London ON
| | - Mona Alameldin
- Department of Anatomical Pathology, Western University, London ON
| | - Joe King Lee
- Division of Urology, Department of Surgery, Western University, London ON
| | - Kyle MacDonald
- Department of Microbiology and Immunology, Western University, London ON
| | - Lee W Goneau
- Department of Microbiology and Immunology, Western University, London ON
| | - Peter Cadieux
- Department of Microbiology and Immunology, Western University, London ON
| | - Jeremy Burton
- Division of Urology, Department of Surgery, Western University, London ON; ; Department of Microbiology and Immunology, Western University, London ON
| | - Stephen Pautler
- Division of Urology, Department of Surgery, Western University, London ON; ; Division of Surgical Oncology, Department of Oncology, Western University, London ON
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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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Subramanian VS, Nabokina SM, Patton JR, Marchant JS, Moradi H, Said HM. Glyoxalate reductase/hydroxypyruvate reductase interacts with the sodium-dependent vitamin C transporter-1 to regulate cellular vitamin C homeostasis. Am J Physiol Gastrointest Liver Physiol 2013; 304:G1079-86. [PMID: 23599041 PMCID: PMC3680717 DOI: 10.1152/ajpgi.00090.2013] [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
The human sodium-dependent vitamin C transporter 1 (hSVCT1) contributes to cellular uptake of ascorbic acid (AA). Although different aspects of hSVCT1 cell biology have been extensively studied, nothing is currently known about the broader hSVCT1 interactome that modulates its role in cellular physiology. Here, we identify the enzyme human glyoxalate reductase/hydroxypyruvate reductase (hGR/HPR) as an hSVCT1 associated protein by yeast two-hybrid (Y2H) screening of a human liver cDNA library. The interaction between hSVCT1 and hGR/HPR was further confirmed by in vitro GST pull-down assay, in vivo coimmunoprecipitation and mammalian two-hybrid firefly luciferase assays. This interaction had functional significance as coexpression of hGR/HPR with hSVCT1 led to an increase in AA uptake. Reciprocally, siRNA-mediated knockdown of endogenous hGR/HPR led to an inhibition of AA uptake. Given that oxalate is a degradation product of vitamin C and hGR/HPR acts to limit cellular oxalate levels, this association physically couples two independent regulators of cellular oxalate production. Furthermore, confocal imaging of human liver HepG2 cells coexpressing GFP-hSVCT1 and hGR/HPR-mCherry demonstrated that these two proteins colocalize within a subpopulation of intracellular organelles. This provides a possible molecular basis for organellar AA transport and regulation of local glyoxylate/glycolate concentration in the vicinity of organelle membranes.
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Affiliation(s)
- Veedamali S. Subramanian
- 1Departments of Medicine, Physiology and Biophysics, University of California, Irvine, California; ,2Department of Veterans Affairs Medical Center, Long Beach, California; and
| | - Svetlana M. Nabokina
- 1Departments of Medicine, Physiology and Biophysics, University of California, Irvine, California; ,2Department of Veterans Affairs Medical Center, Long Beach, California; and
| | - Joseph R. Patton
- 3Department of Pharmacology, University of Minnesota Medical School, Minneapolis, Minnesota
| | - Jonathan S. Marchant
- 3Department of Pharmacology, University of Minnesota Medical School, Minneapolis, Minnesota
| | - Hamid Moradi
- 1Departments of Medicine, Physiology and Biophysics, University of California, Irvine, California; ,2Department of Veterans Affairs Medical Center, Long Beach, California; and
| | - Hamid M. Said
- 1Departments of Medicine, Physiology and Biophysics, University of California, Irvine, California; ,2Department of Veterans Affairs Medical Center, Long Beach, California; and
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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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Subramanian VS, Subramanya SB, Ghosal A, Marchant JS, Harada A, Said HM. Modulation of function of sodium-dependent vitamin C transporter 1 (SVCT1) by Rab8a in intestinal epithelial cells: studies utilizing Caco-2 cells and Rab8a knockout mice. Dig Dis Sci 2013; 58:641-9. [PMID: 23014846 PMCID: PMC3547156 DOI: 10.1007/s10620-012-2388-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 08/24/2012] [Indexed: 01/19/2023]
Abstract
BACKGROUND Ascorbic acid (AA) is required for normal human health and development. Human intestine expresses two sodium-dependent vitamin C transporters (hSVCT-1 and -2) that mediate cellular AA transport, with hSVCT1 targeting to the apical membrane of polarized epithelia. Studies have shown a role for the Rab8a in the apical membrane targeting of transporters in intestinal cells. AIMS The purpose of this study was to determine whether Rab8a impacts the function and/or targeting of hSVCT1, and intestinal AA uptake. METHODS We used human intestinal cells and cells from a Rab8a knockout mouse. (14)C-AA uptake was performed to determine functionality. PCR and western blotting were performed to determine RNA and protein expression, respectively. Confocal imaging was performed to determine co-localization. RESULTS We show that hSVCT1 co-localized with Rab8a in intestinal cells. Knockdown of Rab8a lead to a significant inhibition in AA uptake and cell surface biotinylation studies revealed a lower cell surface expression of hSVCT1 in Rab8a siRNA-treated cells. Similarly, in the small intestine of a Rab8a knockout mouse, AA uptake was significantly inhibited. This effect again resulted from a decreased expression level of mSVCT1 protein, even though mRNA expression of SVCT1 was similar in intestinal cells from Rab8a knockout and wild-type litter-mates. The latter data are suggestive of enhanced lysosomal degradation of hSVCT1 protein in Rab8a-deficient cells; indeed, confocal imaging of Rab8a siRNA-treated intestinal cells revealed a strong overlap between hSVCT1-YFP and LAMP1-RFP. CONCLUSIONS These findings show a role for Rab8a in the physiological function of hSVCT1 in intestinal epithelia.
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Affiliation(s)
- Veedamali S. Subramanian
- Departments of Medicine, Physiology and Biophysics, University of California, Irvine, CA 92697
,Department of Veterans Affairs Medical Center, Long Beach, CA 90822
,To whom correspondence may be addressed: , Phone: 562-826-5803; Fax: 562-826-5018
| | - Sandeep B. Subramanya
- Departments of Medicine, Physiology and Biophysics, University of California, Irvine, CA 92697
,Department of Veterans Affairs Medical Center, Long Beach, CA 90822
| | - Abhisek Ghosal
- Departments of Medicine, Physiology and Biophysics, University of California, Irvine, CA 92697
,Department of Veterans Affairs Medical Center, Long Beach, CA 90822
| | | | | | - Hamid M. Said
- Departments of Medicine, Physiology and Biophysics, University of California, Irvine, CA 92697
,Department of Veterans Affairs Medical Center, Long Beach, CA 90822
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Ghosal A, Lambrecht N, Subramanya SB, Kapadia R, Said HM. Conditional knockout of the Slc5a6 gene in mouse intestine impairs biotin absorption. Am J Physiol Gastrointest Liver Physiol 2013; 304:G64-71. [PMID: 23104561 PMCID: PMC3543636 DOI: 10.1152/ajpgi.00379.2012] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Accepted: 10/19/2012] [Indexed: 01/31/2023]
Abstract
The Slc5a6 gene expresses a plasma membrane protein involved in the transport of the water-soluble vitamin biotin; the transporter is commonly referred to as the sodium-dependent multivitamin transporter (SMVT) because it also transports pantothenic acid and lipoic acid. The relative contribution of the SMVT system toward carrier-mediated biotin uptake in the native intestine in vivo has not been established. We used a Cre/lox technology to generate an intestine-specific (conditional) SMVT knockout (KO) mouse model to address this issue. The KO mice exhibited absence of expression of SMVT in the intestine compared with sex-matched littermates as well as the expected normal SMVT expression in other tissues. About two-thirds of the KO mice died prematurely between the age of 6 and 10 wk. Growth retardation, decreased bone density, decreased bone length, and decreased biotin status were observed in the KO mice. Microscopic analysis showed histological abnormalities in the small bowel (shortened villi, dysplasia) and cecum (chronic active inflammation, dysplasia) of the KO mice. In vivo (and in vitro) transport studies showed complete inhibition in carrier-mediated biotin uptake in the intestine of the KO mice compared with their control littermates. These studies provide the first in vivo confirmation in native intestine that SMVT is solely responsible for intestinal biotin uptake. These studies also provide evidence for a casual association between SMVT function and normal intestinal health.
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Affiliation(s)
- Abhisek Ghosal
- Department of Medicine, University of California, School of Medicine, Irvine, CA, USA
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Subramanya SB, Subramanian VS, Sekar VT, Said HM. Thiamin uptake by pancreatic acinar cells: effect of chronic alcohol feeding/exposure. Am J Physiol Gastrointest Liver Physiol 2011; 301:G896-904. [PMID: 21868632 PMCID: PMC3220324 DOI: 10.1152/ajpgi.00308.2011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Thiamin is important for normal function of pancreatic acinar cells, but little is known about its mechanism of uptake and about the effect of chronic alcohol use on the process. We addressed these issues using freshly isolated rat primary and rat-derived cultured AR42J pancreatic acinar cells as models. Results showed thiamin uptake by both primary and cultured AR42J pancreatic acinar cells to be via a specific carrier-mediated mechanism and that both of the thiamin transporters 1 and 2 (THTR-1 and THTR-2) are expressed in these cells. Chronic alcohol feeding of rats was found to lead to a significant inhibition of carrier-mediated thiamin uptake by pancreatic acinar cells and was associated with a significant reduction in level of expression of THTR-1 and THTR-2 at the protein and mRNA levels. Chronic exposure (96 h) of AR42J cells to alcohol also led to a significant decreased carrier-mediated thiamin uptake, an effect that was associated with a significant decrease in the activity of the human SLC19A2 and SLC19A3 promoters expressed in these cells. We also examined the effect of chronic alcohol feeding of rats on level of expression of key thiamin metabolizing enzymes (thiamin phosphokinase and thiamin pyrophosphatase) as well as on level of expression of the mitochondrial thiamin pyrophosphate transporter of pancreatic acinar cells and observed a significant inhibition in all these parameters. These results demonstrate for the first time that thiamin uptake by pancreatic acinar cells is via a carrier-mediated process and that both the THTR-1 as well as THTR-2 are expressed in these cells. Also, chronic alcohol feeding/exposure inhibits thiamin uptake process and the inhibition is, at least in part, being exerted at the transcriptional level. Furthermore, chronic alcohol feeding also negatively impacts intracellular parameters of thiamin metabolism in pancreatic acinar cells.
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Affiliation(s)
- Sandeep B. Subramanya
- Departments of Medicine and Physiology/Biophysics, University of California, Irvine and Department of Veterans Affairs Medical Center, Long Beach, California
| | - Veedamali S. Subramanian
- Departments of Medicine and Physiology/Biophysics, University of California, Irvine and Department of Veterans Affairs Medical Center, Long Beach, California
| | - V. Thillai Sekar
- Departments of Medicine and Physiology/Biophysics, University of California, Irvine and Department of Veterans Affairs Medical Center, Long Beach, California
| | - Hamid M. Said
- Departments of Medicine and Physiology/Biophysics, University of California, Irvine and Department of Veterans Affairs Medical Center, Long Beach, California
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Abstract
Our knowledge of the mechanisms and regulation of intestinal absorption of water-soluble vitamins under normal physiological conditions, and of the factors/conditions that affect and interfere with theses processes has been significantly expanded in recent years as a result of the availability of a host of valuable molecular/cellular tools. Although structurally and functionally unrelated, the water-soluble vitamins share the feature of being essential for normal cellular functions, growth and development, and that their deficiency leads to a variety of clinical abnormalities that range from anaemia to growth retardation and neurological disorders. Humans cannot synthesize water-soluble vitamins (with the exception of some endogenous synthesis of niacin) and must obtain these micronutrients from exogenous sources. Thus body homoeostasis of these micronutrients depends on their normal absorption in the intestine. Interference with absorption, which occurs in a variety of conditions (e.g. congenital defects in the digestive or absorptive system, intestinal disease/resection, drug interaction and chronic alcohol use), leads to the development of deficiency (and sub-optimal status) and results in clinical abnormalities. It is well established now that intestinal absorption of the water-soluble vitamins ascorbate, biotin, folate, niacin, pantothenic acid, pyridoxine, riboflavin and thiamin is via specific carrier-mediated processes. These processes are regulated by a variety of factors and conditions, and the regulation involves transcriptional and/or post-transcriptional mechanisms. Also well recognized now is the fact that the large intestine possesses specific and efficient uptake systems to absorb a number of water-soluble vitamins that are synthesized by the normal microflora. This source may contribute to total body vitamin nutrition, and especially towards the cellular nutrition and health of the local colonocytes. The present review aims to outline our current understanding of the mechanisms involved in intestinal absorption of water-soluble vitamins, their regulation, the cell biology of the carriers involved and the factors that negatively affect these absorptive events.
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Affiliation(s)
- Hamid M Said
- School of Medicine, University of California-Irvine, Irvine, CA 92697, USA.
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Subramanian VS, Rapp L, Marchant JS, Said HM. Role of cysteine residues in cell surface expression of the human riboflavin transporter-2 (hRFT2) in intestinal epithelial cells. Am J Physiol Gastrointest Liver Physiol 2011; 301:G100-9. [PMID: 21512156 PMCID: PMC3129935 DOI: 10.1152/ajpgi.00120.2011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The water-soluble vitamin B2 (riboflavin, RF) is an essential micronutrient for normal cell function and survival. Recent studies have identified a role for the human riboflavin transporter-2 (hRFT2) in normal intestinal RF absorption. However, little is known about the cell biology of this transporter and specifically about the molecular determinant(s) that dictate its cell surface expression in human intestinal epithelial cells. Here we show that the full-length hRFT2 protein fused to green fluorescent protein (GFP) (GFP-hRFT2) is expressed exclusively at the apical membrane domain of Caco-2 cells. COOH-terminal sequence was essential in dictating cell surface expression with a specific role for conserved cysteine residues (C463 and C467). Mutation of C463 and C467 ablated RF uptake, explained by retention of the constructs within the endoplasmic reticulum. Modeling analysis suggested a potential disulfide bridge between C463 and C386. Consistent with this prediction, mutating the C386 site in the context of the full-length transporter resulted in intracellular retention, whereas mutation of another conserved cysteine (C326A) was without effect on hRFT2 targeting. Intracellular trafficking of hRFT2 was also examined and appeared to involve distinct vesicular structures, the motility of vesicles critically dependent on an intact microtubule network. These results demonstrate a potential role for specific cysteine residues in the cell surface expression of the hRFT2 in human intestinal epithelial cells.
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Affiliation(s)
- Veedamali S. Subramanian
- 1Departments of Medicine and Physiology/Biophysics, University of California Medical School, Irvine, California; ,2Department of Veterans Affairs Medical Center, Long Beach, California;
| | - Laramie Rapp
- 3Department of Pharmacology, University of Minnesota Medical School, Minneapolis, Minnesota
| | - Jonathan S. Marchant
- 3Department of Pharmacology, University of Minnesota Medical School, Minneapolis, Minnesota
| | - Hamid M. Said
- 1Departments of Medicine and Physiology/Biophysics, University of California Medical School, Irvine, California; ,2Department of Veterans Affairs Medical Center, Long Beach, California;
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Subramanian VS, Subramanya SB, Said HM. Chronic alcohol exposure negatively impacts the physiological and molecular parameters of the renal biotin reabsorption process. Am J Physiol Renal Physiol 2011; 300:F611-7. [PMID: 21209005 DOI: 10.1152/ajprenal.00707.2010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Normal body homeostasis of biotin is critically dependent on its renal recovery by kidney proximal tubular epithelial cells, a process that is mediated by the sodium-dependent multivitamin transporter (SMVT; a product of the SLC5A6 gene). Chronic ethanol consumption interferes with the renal reabsorption process of a variety of nutrients, including water-soluble vitamins. To date, however, there is nothing known about the effect of chronic alcohol feeding on physiological and molecular parameters of the renal biotin reabsorption process. We addressed these issues using rats and transgenic mice carrying the human SLC5A6 (P1P2) 5'-regulatory region as an in vivo model systems of alcohol exposure, and cultured human renal proximal tubular epithelial HK-2 cells chronically exposed to alcohol as an in vitro model of alcohol exposure. The [(3)H]biotin uptake results showed that chronic ethanol feeding in rats leads to a significant inhibition in carrier-mediated biotin transport across both renal brush border and basolateral membrane domains. This inhibition was associated with a marked reduction in the level of expression of SMVT protein, mRNA, and heterogenous nuclear RNA (hnRNA). Furthermore, studies with transgenic mice carrying the SLC5A6 5'-regulatory region showed that chronic alcohol feeding leads to a significant decrease in promoter activity. Studies with HK-2 cells chronically exposed to alcohol again showed a marked reduction in carrier-mediated biotin uptake, which was associated with a significant reduction in promoter activity of the human SLC5A6 5'-regulatory region. These findings demonstrate for the first time that chronic ethanol feeding inhibits renal biotin transport and that this effect is, at least in part, being exerted at the transcriptional level.
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Affiliation(s)
- Veedamali S Subramanian
- Departments of Medicine, Physiology, and Biophysics, University of California, Irvine, and Department of Veterans AffairsMedical Center, Long Beach, California, USA
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