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Uebanso T, Shimohata T, Mawatari K, Takahashi A. Functional Roles of B‐Vitamins in the Gut and Gut Microbiome. Mol Nutr Food Res 2020; 64:e2000426. [DOI: 10.1002/mnfr.202000426] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 07/31/2020] [Indexed: 01/19/2023]
Affiliation(s)
- Takashi Uebanso
- Department of Preventive Environment and Nutrition, Institute of Biomedical Sciences Tokushima University Graduate School Tokushima 770–8503 Japan
| | - Takaaki Shimohata
- Department of Preventive Environment and Nutrition, Institute of Biomedical Sciences Tokushima University Graduate School Tokushima 770–8503 Japan
| | - Kazuaki Mawatari
- Department of Preventive Environment and Nutrition, Institute of Biomedical Sciences Tokushima University Graduate School Tokushima 770–8503 Japan
| | - Akira Takahashi
- Department of Preventive Environment and Nutrition, Institute of Biomedical Sciences Tokushima University Graduate School Tokushima 770–8503 Japan
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Cheung SG, Goldenthal AR, Uhlemann AC, Mann JJ, Miller JM, Sublette ME. Systematic Review of Gut Microbiota and Major Depression. Front Psychiatry 2019; 10:34. [PMID: 30804820 PMCID: PMC6378305 DOI: 10.3389/fpsyt.2019.00034] [Citation(s) in RCA: 302] [Impact Index Per Article: 60.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 01/21/2019] [Indexed: 11/17/2022] Open
Abstract
Background: Recently discovered relationships between the gastrointestinal microbiome and the brain have implications for psychiatric disorders, including major depressive disorder (MDD). Bacterial transplantation from MDD patients to rodents produces depression-like behaviors. In humans, case-control studies have examined the gut microbiome in healthy and affected individuals. We systematically reviewed existing studies comparing gut microbial composition in MDD and healthy volunteers. Methods: A PubMed literature search combined the terms "depression," "depressive disorder," "stool," "fecal," "gut," and "microbiome" to identify human case-control studies that investigated relationships between MDD and microbiota quantified from stool. We evaluated the resulting studies, focusing on bacterial taxa that were different between MDD and healthy controls. Results: Six eligible studies were found in which 50 taxa exhibited differences (p < 0.05) between patients with MDD and controls. Patient characteristics and methodologies varied widely between studies. Five phyla-Bacteroidetes, Firmicutes, Actinobacteria, Fusobacteria, and Protobacteria-were represented; however, divergent results occurred across studies for all phyla. The largest number of differentiating taxa were within phylum Firmicutes, in which nine families and 12 genera differentiated the diagnostic groups. The majority of these families and genera were found to be statistically different between the two groups in two identified studies. Family Lachnospiraceae differentiated the diagnostic groups in four studies (with an even split in directionality). Across all five phyla, nine genera were higher in MDD (Anaerostipes, Blautia, Clostridium, Klebsiella, Lachnospiraceae incertae sedis, Parabacteroides, Parasutterella, Phascolarctobacterium, and Streptococcus), six were lower (Bifidobacterium, Dialister, Escherichia/Shigella, Faecalibacterium, and Ruminococcus), and six were divergent (Alistipes, Bacteroides, Megamonas, Oscillibacter, Prevotella, and Roseburia). We highlight mechanisms and products of bacterial metabolism as they may relate to the etiology of depression. Conclusions: No consensus has emerged from existing human studies of depression and gut microbiome concerning which bacterial taxa are most relevant to depression. This may in part be due to differences in study design. Given that bacterial functions are conserved across taxonomic groups, we propose that studying microbial functioning may be more productive than a purely taxonomic approach to understanding the gut microbiome in depression.
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Affiliation(s)
- Stephanie G. Cheung
- Division of Consultation-Liaison Psychiatry, Columbia University, New York, NY, United States
- Department of Psychiatry, Columbia University, New York, NY, United States
| | - Ariel R. Goldenthal
- Department of Psychiatry, Columbia University, New York, NY, United States
- Molecular Imaging & Neuropathology Area, New York State Psychiatric Institute, New York, NY, United States
| | - Anne-Catrin Uhlemann
- Division of Infectious Diseases, Department of Medicine, Columbia University, New York, NY, United States
- Microbiome & Pathogen Genomics Core, Columbia University, New York, NY, United States
| | - J. John Mann
- Department of Psychiatry, Columbia University, New York, NY, United States
- Molecular Imaging & Neuropathology Area, New York State Psychiatric Institute, New York, NY, United States
- Department of Radiology, Columbia University, New York, NY, United States
| | - Jeffrey M. Miller
- Department of Psychiatry, Columbia University, New York, NY, United States
- Molecular Imaging & Neuropathology Area, New York State Psychiatric Institute, New York, NY, United States
| | - M. Elizabeth Sublette
- Department of Psychiatry, Columbia University, New York, NY, United States
- Molecular Imaging & Neuropathology Area, New York State Psychiatric Institute, New York, NY, United States
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Poupeau A, Garde C, Sulek K, Citirikkaya K, Treebak JT, Arumugam M, Simar D, Olofsson LE, Bäckhed F, Barrès R. Genes controlling the activation of natural killer lymphocytes are epigenetically remodeled in intestinal cells from germ-free mice. FASEB J 2018; 33:2719-2731. [PMID: 30303739 PMCID: PMC6338647 DOI: 10.1096/fj.201800787r] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Remodeling of the gut microbiota is implicated in various metabolic and inflammatory diseases of the gastrointestinal tract. We hypothesized that the gut microbiota affects the DNA methylation profile of intestinal epithelial cells (IECs) which could, in turn, alter intestinal function. In this study, we used mass spectrometry and methylated DNA capture to respectively investigate global and genome-wide DNA methylation of intestinal epithelial cells from germ-free (GF) and conventionally raised mice. In colonic IECs from GF mice, DNA was markedly hypermethylated. This was associated with a dramatic loss of ten-eleven-translocation activity, a lower DNA methyltransferase activity and lower circulating levels of the 1-carbon metabolite, folate. At the gene level, we found an enrichment for differentially methylated regions proximal to genes regulating the cytotoxicity of NK cells (false-discovery rate < 8.9E−6), notably genes regulating the cross-talk between NK cells and target cells, such as members of the NK group 2 member D ligand superfamily Raet. This distinct epigenetic signature was associated with a marked decrease in Raet1 expression and a loss of CD56+/CD45+ cells in the intestine of GF mice. Thus, our results indicate that altered activity of methylation-modifying enzymes in GF mice influences the IEC epigenome and modulates the crosstalk between IECs and NK cells. Epigenetic reprogramming of IECs may modulate intestinal function in diseases associated with altered gut microbiota.—Poupeau, A., Garde, C., Sulek, K., Citirikkaya, K., Treebak, J. T., Arumugam, M., Simar, D., Olofsson, L. E., Bäckhed, F., Barrès, R. Genes controlling the activation of natural killer lymphocytes are epigenetically remodeled in intestinal cells from germ-free mice.
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Affiliation(s)
- Audrey Poupeau
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Christian Garde
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Karolina Sulek
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kiymet Citirikkaya
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jonas T Treebak
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Manimozhiyan Arumugam
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - David Simar
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Mechanisms of Disease and Translational Research, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia; and
| | - Louise E Olofsson
- Department of Molecular and Clinical Medicine, Wallenberg Laboratory and Sahlgrenska Center for Cardiovascular and Metabolic Research, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden
| | - Fredrik Bäckhed
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Molecular and Clinical Medicine, Wallenberg Laboratory and Sahlgrenska Center for Cardiovascular and Metabolic Research, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden
| | - Romain Barrès
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Lakoff A, Fazili Z, Aufreiter S, Pfeiffer CM, Connolly B, Gregory JF, Pencharz PB, O'Connor DL. Folate is absorbed across the human colon: evidence by using enteric-coated caplets containing 13C-labeled [6S]-5-formyltetrahydrofolate. Am J Clin Nutr 2014; 100:1278-86. [PMID: 25332326 PMCID: PMC4823011 DOI: 10.3945/ajcn.114.091785] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Folate intakes that do not meet or greatly exceed requirements may be associated with negative health outcomes. A better understanding of contributors that influence the input side will help establish dietary guidance that ensures health benefits without associated risks. Colonic microbiota produce large quantities of folate, and [(13)C5]5-formyltetrahydrofolate infused during colonoscopy is absorbed. However, it is unclear if significant quantities of folate are absorbed in an intact microbiome. OBJECTIVE We determined whether and how much of a physiologic dose of [(13)C5]5-formyltetrahydrofolate delivered in a pH-sensitive enteric caplet to an intact colonic microbiome is absorbed. DESIGN Healthy adults ingested a specially designed pH-sensitive acrylic copolymer-coated barium sulfate caplet that contained 855 nmol (400 μg) [(13)C5]5-formyltetrahydrofolate. After a washout period ≥ 4 wk, subjects received an intravenous injection of the same compound (214 nmol). Serially collected blood samples before and after each test dose were analyzed by using a microbiological assay and liquid chromatography-tandem mass spectrometry. RESULTS Caplet disintegration in the colon was observed by fluoroscopic imaging for 6 subjects with a mean (± SD) complete disintegration time of 284 ± 155 min. The mean (± SEM) rate of appearance of [(13)C5]5-methyltetrahydrofolate in plasma was 0.33 ± 0.09 (caplet) and 5.8 ± 1.2 (intravenous) nmol/h. Likely because of the significant time in the colon, the mean apparent absorption across the colon was 46%. CONCLUSIONS Folate is absorbed across the colon in humans with an undisturbed microbiome. This finding and previous observations of the size of the colonic depot of folate and its potential for manipulation by diet (eg, dietary fiber, oligosaccharides, and probiotics) suggest that an individual's dietary folate requirement may differ depending on the consumption of dietary constituents that affect the size and composition of their gastrointestinal microbiota. In addition, a systematic investigation of the role of colonic folate on gastrointestinal development and the prevention of colorectal cancer is warranted. This trial was registered at clinicaltrials.gov as NCT00941174.
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Affiliation(s)
- Alanna Lakoff
- From the Departments of Nutritional Sciences (AL, PBP, and DLO), Radiology (BC), and Paediatrics (PBP), University of Toronto, Toronto, Canada; The Research Institute, The Hospital for Sick Children, Toronto, Canada (AL, SA, BC, PBP, and DLO); CDC, Atlanta, GA (ZF and CMP); and the Food Science and Human Nutrition Department, University of Florida, Gainesville, FL (JFG)
| | - Zia Fazili
- From the Departments of Nutritional Sciences (AL, PBP, and DLO), Radiology (BC), and Paediatrics (PBP), University of Toronto, Toronto, Canada; The Research Institute, The Hospital for Sick Children, Toronto, Canada (AL, SA, BC, PBP, and DLO); CDC, Atlanta, GA (ZF and CMP); and the Food Science and Human Nutrition Department, University of Florida, Gainesville, FL (JFG)
| | - Susanne Aufreiter
- From the Departments of Nutritional Sciences (AL, PBP, and DLO), Radiology (BC), and Paediatrics (PBP), University of Toronto, Toronto, Canada; The Research Institute, The Hospital for Sick Children, Toronto, Canada (AL, SA, BC, PBP, and DLO); CDC, Atlanta, GA (ZF and CMP); and the Food Science and Human Nutrition Department, University of Florida, Gainesville, FL (JFG)
| | - Christine M Pfeiffer
- From the Departments of Nutritional Sciences (AL, PBP, and DLO), Radiology (BC), and Paediatrics (PBP), University of Toronto, Toronto, Canada; The Research Institute, The Hospital for Sick Children, Toronto, Canada (AL, SA, BC, PBP, and DLO); CDC, Atlanta, GA (ZF and CMP); and the Food Science and Human Nutrition Department, University of Florida, Gainesville, FL (JFG)
| | - Bairbie Connolly
- From the Departments of Nutritional Sciences (AL, PBP, and DLO), Radiology (BC), and Paediatrics (PBP), University of Toronto, Toronto, Canada; The Research Institute, The Hospital for Sick Children, Toronto, Canada (AL, SA, BC, PBP, and DLO); CDC, Atlanta, GA (ZF and CMP); and the Food Science and Human Nutrition Department, University of Florida, Gainesville, FL (JFG)
| | - Jesse F Gregory
- From the Departments of Nutritional Sciences (AL, PBP, and DLO), Radiology (BC), and Paediatrics (PBP), University of Toronto, Toronto, Canada; The Research Institute, The Hospital for Sick Children, Toronto, Canada (AL, SA, BC, PBP, and DLO); CDC, Atlanta, GA (ZF and CMP); and the Food Science and Human Nutrition Department, University of Florida, Gainesville, FL (JFG)
| | - Paul B Pencharz
- From the Departments of Nutritional Sciences (AL, PBP, and DLO), Radiology (BC), and Paediatrics (PBP), University of Toronto, Toronto, Canada; The Research Institute, The Hospital for Sick Children, Toronto, Canada (AL, SA, BC, PBP, and DLO); CDC, Atlanta, GA (ZF and CMP); and the Food Science and Human Nutrition Department, University of Florida, Gainesville, FL (JFG)
| | - Deborah L O'Connor
- From the Departments of Nutritional Sciences (AL, PBP, and DLO), Radiology (BC), and Paediatrics (PBP), University of Toronto, Toronto, Canada; The Research Institute, The Hospital for Sick Children, Toronto, Canada (AL, SA, BC, PBP, and DLO); CDC, Atlanta, GA (ZF and CMP); and the Food Science and Human Nutrition Department, University of Florida, Gainesville, FL (JFG)
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Abstract
The properties of intestinal folate absorption were documented decades ago. However, it was only recently that the proton-coupled folate transporter (PCFT) was identified and its critical role in folate transport across the apical brush-border membrane of the proximal small intestine established by the loss-of-function mutations identified in the PCFT gene in subjects with hereditary folate malabsorption and, more recently, by the Pcft-null mouse. This article reviews the current understanding of the properties of PCFT-mediated transport and how they differ from those of the reduced folate carrier. Other processes that contribute to the transport of folates across the enterocyte, along with the contribution of the enterohepatic circulation, are considered. Important unresolved issues are addressed, including the mechanism of intestinal folate absorption in the absence of PCFT and regulation of PCFT gene expression. The impact of a variety of ions, organic molecules, and drugs on PCFT-mediated folate transport is described.
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Affiliation(s)
- Michele Visentin
- Departments of Molecular Pharmacology and Medicine, Albert Einstein College of Medicine, Bronx, New York 10461; , , ,
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Amato KR, Leigh SR, Kent A, Mackie RI, Yeoman CJ, Stumpf RM, Wilson BA, Nelson KE, White BA, Garber PA. The role of gut microbes in satisfying the nutritional demands of adult and juvenile wild, black howler monkeys (Alouatta pigra). AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2014; 155:652-64. [DOI: 10.1002/ajpa.22621] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 09/09/2014] [Accepted: 09/10/2014] [Indexed: 01/22/2023]
Affiliation(s)
- Katherine R. Amato
- Program in Ecology, Evolution, and Conservation Biology; University of Illinois; Urbana IL 61801
- Department of Anthropology; University of Colorado; Boulder CO 80309
| | - Steven R. Leigh
- Department of Anthropology; University of Colorado; Boulder CO 80309
| | - Angela Kent
- Department of Natural Resources and Environmental Sciences; University of Illinois; Urbana IL 61801
| | - Roderick I. Mackie
- Department of Animal Sciences; University of Illinois; Urbana IL 61801
- Institute for Genomic Biology, University of Illinois; Urbana IL 61801
| | - Carl J. Yeoman
- Department of Animal and Range Sciences; Montana State University; Bozeman MT 59717
| | - Rebecca M. Stumpf
- Institute for Genomic Biology, University of Illinois; Urbana IL 61801
- Department of Anthropology; University of Illinois; Urbana IL 80301
| | - Brenda A. Wilson
- Institute for Genomic Biology, University of Illinois; Urbana IL 61801
- Department of Microbiology; University of Illinois; Urbana IL 61801
| | | | - Bryan A. White
- Department of Animal Sciences; University of Illinois; Urbana IL 61801
- Institute for Genomic Biology, University of Illinois; Urbana IL 61801
| | - Paul A. Garber
- Department of Anthropology; University of Illinois; Urbana IL 80301
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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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Jeffery IB, O’Toole PW. Diet-microbiota interactions and their implications for healthy living. Nutrients 2013; 5:234-52. [PMID: 23344252 PMCID: PMC3571646 DOI: 10.3390/nu5010234] [Citation(s) in RCA: 138] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Revised: 01/10/2013] [Accepted: 01/10/2013] [Indexed: 02/06/2023] Open
Abstract
It is well established that diet influences the health of an individual and that a diet rich in plant-based foods has many advantages in relation to the health and well-being of an individual. What has been unclear until recently is the large contribution of the gut microbiota to this effect. As well as providing basic nutritional requirements, the long-term diet of an animal modifies its gut microbiota. In adults, diets that have a high proportion of fruit and vegetables and a low consumption of meat are associated with a highly diverse microbiota and are defined by a greater abundance of Prevotella compared to Bacteroides, while the reverse is associated with a diet that contains a low proportion of plant-based foods. Furthermore, it is becoming increasingly clear that the effect of the microbial ecology of the gut goes beyond the local gut immune system and is implicated in immune-related disorders, such as IBS, diabetes and inflamm-ageing. In this review, we investigate the evidence that a balanced diet leads to a balanced, diverse microbiota with significant consequences for healthy ageing by focusing on conditions of interest.
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Affiliation(s)
- Ian B. Jeffery
- Department of Microbiology, University College Cork, College Road, Cork, Ireland; E-Mail:
- Alimentary Pharmabiotic Centre, University College Cork, College Road, Cork, Ireland
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +353-(0)21-490-1306; Fax: +353-(0)21-490-3997
| | - Paul W. O’Toole
- Department of Microbiology, University College Cork, College Road, Cork, Ireland; E-Mail:
- Alimentary Pharmabiotic Centre, University College Cork, College Road, Cork, Ireland
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Williams EA, Welfare M, Spiers A, Hill MH, Bal W, Gibney ER, Duckworth Y, Powers HJ, Mathers JC. Systemic folate status, rectal mucosal folate concentration and dietary intake in patients at differential risk of bowel cancer (The FAB2 Study). Eur J Nutr 2012; 52:1801-10. [PMID: 23271614 DOI: 10.1007/s00394-012-0483-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 12/09/2012] [Indexed: 12/14/2022]
Abstract
BACKGROUND/OBJECTIVES Folate has been strongly implicated in the aetiology of colorectal cancer. However, the relationship between dietary folate intake, rectal mucosal folate status and colorectal cancer risk is uncertain. The study aimed to estimate nutrient intakes and measure systemic folate status and rectal mucosal folate concentration in people at differential risk of developing colorectal cancer. METHODS Two hundred and twenty-eight individuals were recruited from gastroenterology clinics and subdivided into three patient groups: untreated colorectal cancer (n = 43), adenomatous polyps (n = 90) or normal bowel (n = 95). Biopsies from macroscopically normal rectal mucosa and blood were collected and used for the measurement of rectal mucosal 5-methyltetrahydrofolate (5-MeTHF) and systemic markers of folate status, respectively. Nutrient intake was estimated using a validated food frequency questionnaire. RESULTS Dietary intake variables, plasma 5-MeTHF and red cell folate and plasma homocysteine concentrations were similar in all three subject groups and 95% CI fell within normal range for each variable. Rectal mucosal 5-MeTHF concentration was higher in the normal mucosa of adenomatous polyp patients than in normal subjects (P = 0.055). Rectal mucosal 5-MeTHF was associated significantly with plasma folate (P < 0.001, r = 0.294), red cell folate (P = 0.014, r = 0.305), plasma homocysteine (P = 0.017, r = -0.163) and dietary folate intake (P = 0.036, r = 0.152). CONCLUSIONS This study demonstrates adequate folate status of patients attending gastroenterology clinics for the investigation of bowel symptoms, with no significant difference in dietary intakes or systemic folate status indices according to diagnosis. Rectal mucosal 5-MeTHF concentrations were elevated in adenomatous polyp patients, but failed to reach significance. Further studies are required to determine the biological significance of this observation.
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Affiliation(s)
- Elizabeth A Williams
- Human Nutrition Unit, Department of Oncology, Faculty of Medicine, Dentistry and Health Sciences, University of Sheffield, Sheffield, S10 2RX, UK,
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10
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Wani NA, Nada R, Khanduja KL, Kaur J. Decreased activity of folate transporters in lipid rafts resulted in reduced hepatic folate uptake in chronic alcoholism in rats. GENES AND NUTRITION 2012; 8:209-19. [PMID: 22956120 DOI: 10.1007/s12263-012-0318-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Accepted: 08/17/2012] [Indexed: 11/29/2022]
Abstract
Folic acid is an essential nutrient that is required for one-carbon biosynthetic processes and for methylation of biomolecules. Deficiency of this micronutrient leads to disturbances in normal physiology of cell. Chronic alcoholism is well known to be associated with folate deficiency, which is due in part to folate malabsorption. The present study deals with the regulatory mechanisms of folate uptake in liver during chronic alcoholism. Male Wistar rats were fed 1 g/kg body weight/day ethanol (20 % solution) orally for 3 months, and the molecular mechanisms of folate uptake were studied in liver. The characterization of the folate transport system in liver basolateral membrane (BLM) suggested it to be a carrier mediated and acidic pH dependent, with the major involvement of proton coupled folate transporter and folate binding protein in the uptake. The folate transporters were found to be associated with lipid raft microdomain of liver BLM. Moreover, ethanol ingestion decreased the folate transport by altering the Vmax of folate transport process and downregulated the expression of folate transporters in lipid rafts. The decreased transporter levels were associated with reduced protein and mRNA levels of these transporters in liver. The deranged folate uptake together with reduced folate transporter levels in lipid rafts resulted in reduced folate levels in liver and thereby to its reduced levels in serum of ethanol-fed rats. The chronic ethanol ingestion led to decreased folate uptake in liver, which was associated with the decreased number of transporter molecules in the lipid rafts that can be ascribed to the reduced synthesis of these transporters.
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Affiliation(s)
- Nissar Ahmad Wani
- Department of Biochemistry, Postgraduate Institute of Medical Education and Research, Chandigarh, 160 012, India
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11
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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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O'Keefe SJD, Ou J, Aufreiter S, O'Connor D, Sharma S, Sepulveda J, Fukuwatari T, Shibata K, Mawhinney T. Products of the colonic microbiota mediate the effects of diet on colon cancer risk. J Nutr 2009; 139:2044-8. [PMID: 19741203 PMCID: PMC6459055 DOI: 10.3945/jn.109.104380] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
It is estimated that most colon cancers can be attributed to dietary causes. We have hypothesized that diet influences the health of the colonic mucosa through interaction with the microbiota and that it is the milieu interior that regulates mucosal proliferation and therefore cancer risk. To validate this further, we compared colonic contents from healthy 50- to 65-y-old people from populations with high and low risk, specifically low risk Native Africans (cancer incidence <1:100,000; n = 17), high risk African Americans (risk 65:100,000; n = 17), and Caucasian Americans (risk 50:100,000; n = 18). Americans typically consume a high-animal protein and -fat diet, whereas Africans consume a staple diet of maize meal, rich in resistant starch and low in animal products. Following overnight fasting, rapid colonic evacuation was performed with 2 L polyethylene glycol. Total colonic evacuants were analyzed for SCFA, vitamins, nitrogen, and minerals. Total SCFA and butyrate were significantly higher in Native Africans than in both American groups. Colonic folate and biotin content, measured by Lactobacillus rhamnoses and Lactobacillus plantarum ATCC 8014 bioassay, respectively, exceeded normal daily dietary intakes. Compared with Africans, calcium and iron contents were significantly higher in Caucasian Americans and zinc content was significantly higher in African Americans, but nitrogen content did not differ among the 3 groups. In conclusion, the results support our hypothesis that the microbiota mediates the effect diet has on colon cancer risk by their generation of butyrate, folate, and biotin, molecules known to play a key role in the regulation of epithelial proliferation.
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Affiliation(s)
- Stephen J. D. O'Keefe
- University of Pittsburgh, Pittsburgh, PA 15213,To whom correspondence should be addressed. E-mail:
| | - Junhai Ou
- University of Pittsburgh, Pittsburgh, PA 15213
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Jing M, Tactacan G, Rodriguez-Lecompte J, Kroeker A, House J. Molecular cloning and tissue distribution of reduced folate carrier and effect of dietary folate supplementation on the expression of reduced folate carrier in laying hens. Poult Sci 2009; 88:1939-47. [DOI: 10.3382/ps.2009-00032] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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14
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Aufreiter S, Gregory JF, Pfeiffer CM, Fazili Z, Kim YI, Marcon N, Kamalaporn P, Pencharz PB, O'Connor DL. Folate is absorbed across the colon of adults: evidence from cecal infusion of (13)C-labeled [6S]-5-formyltetrahydrofolic acid. Am J Clin Nutr 2009; 90:116-23. [PMID: 19439459 PMCID: PMC6443296 DOI: 10.3945/ajcn.2008.27345] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Folate deficiency increases the risk of several human diseases. Likewise, high intakes of folate, particularly synthetic folic acid intake, may be associated with adverse health outcomes in humans. A more comprehensive understanding of the "input side" of folate nutrition may help to set dietary recommendations that strike the right balance between health benefits and risks. It is well known that the microflora in the colon produce large quantities of folate that approach or exceed recommended dietary intakes; however, there is no direct evidence of the bioavailability of this pool in humans. OBJECTIVE The objective was to determine whether, and to what extent, the natural folate vitamer 5-formyltetrahydrofolic acid is absorbed across the intact colon of humans. DESIGN During screening colonoscopy, 684 nmol (320 microg) [(13)C]glutamyl-5-formyltetrahydrofolic acid was infused directly into the cecum of 6 healthy adults. Three or more weeks later, each subject received an intravenous injection of the same compound (172 nmol). Blood samples were collected before and after each treatment. The ratio of labeled to unlabeled folates was determined in plasma by tandem mass spectrometry. RESULTS The apparent rate of folate absorption across the colon of a bolus dose of [(13)C]5-formyltetrahydrofolic acid infused into the cecum was 0.6 +/- 0.2 nmol/h, as determined by the appearance of [(13)C(5)]5-methyltetrahydrofolic acid in plasma. In comparison, the rate of appearance of [(13)C(5)]5-methyltetrahydrofolic acid after an intravenous injection of [(13)C(5)]5-formyltetrahydrofolate was 7 +/- 1.2 nmol/h. CONCLUSION Physiologic doses of natural folate are absorbed across the intact colon in humans.
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Affiliation(s)
- Susanne Aufreiter
- Department of Nutritional Sciences, University of Toronto, Toronto, Canada
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Subramanian VS, Marchant JS, Boulware MJ, Ma TY, Said HM. Membrane targeting and intracellular trafficking of the human sodium-dependent multivitamin transporter in polarized epithelial cells. Am J Physiol Cell Physiol 2009; 296:C663-71. [PMID: 19211916 PMCID: PMC2670647 DOI: 10.1152/ajpcell.00396.2008] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Accepted: 02/06/2009] [Indexed: 11/22/2022]
Abstract
The human sodium-dependent multivitamin transporter (hSMVT) mediates sodium-dependent uptake of biotin in renal and intestinal epithelia. To date, however, there is nothing known about the structure-function relationship or targeting sequences in the hSMVT polypeptide that control its polarized expression within epithelia. Here, we focused on the role of the COOH-terminal tail of hSMVT in the targeting and functionality of this transporter. A full-length hSMVT-green fluorescent protein (GFP) fusion protein was functional and expressed at the apical membrane in renal and intestinal cell lines. Microtubule disrupting agents disrupted the mobility of trafficking vesicles and impaired cell surface delivery of hSMVT, which was also prevented in cells treated with dynamitin (p50), brefeldin, or monensin. Progressive truncation of the COOH-terminal tail impaired the functionality and targeting of the transporter. First, biotin transport decreased by approximately 20-30% on deletion of up to 15 COOH-terminal amino acids of hSMVT, a decrease mimicked solely by deletion of the terminal PDZ motif (TSL). Second, deletions into the COOH-terminal tail (between residues 584-612, containing a region of predicted high surface accessibility) resulted in a further drop in hSMVT transport (to approximately 40% of wild-type). Third, apical targeting was lost on deletion of a helical-prone region between amino acids 570-584. We conclude that the COOH tail of hSMVT contains several determinants important for polarized targeting and biotin transport.
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Hamid A, Wani NA, Kaur J. New perspectives on folate transport in relation to alcoholism-induced folate malabsorption--association with epigenome stability and cancer development. FEBS J 2009; 276:2175-91. [PMID: 19292860 DOI: 10.1111/j.1742-4658.2009.06959.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Folates are members of the B-class of vitamins, which are required for the synthesis of purines and pyrimidines, and for the methylation of essential biological substances, including phospholipids, DNA, and neurotransmitters. Folates cannot be synthesized de novo by mammals; hence, an efficient intestinal absorption process is required. Intestinal folate transport is carrier-mediated, pH-dependent and electroneutral, with similar affinity for oxidized and reduced folic acid derivatives. The various transporters, i.e. reduced folate carrier, proton-coupled folate transporter, folate-binding protein, and organic anion transporters, are involved in the folate transport process in various tissues. Any impairment in uptake of folate can lead to a state of folate deficiency, the most prevalent vitamin deficiency in world, affecting 10% of the population in the USA. Such impairments in folate transport occur in a variety of conditions, including chronic use of ethanol, some inborn hereditary disorders, and certain diseases. Among these, ethanol ingestion has been the major contributor to folate deficiency. Ethanol-associated folate deficiency can develop because of dietary inadequacy, intestinal malabsorption, altered hepatobiliary metabolism, enhanced colonic metabolism, and increased renal excretion. Ethanol reduces the intestinal and renal uptake of folate by altering the binding and transport kinetics of folate transport systems. Also, ethanol reduces the expression of folate transporters in both intestine and kidney, and this might be a contributing factor for folate malabsorption, leading to folate deficiency. The maintenance of intracellular folate homeostasis is essential for the one-carbon transfer reactions necessary for DNA synthesis and biological methylation reactions. DNA methylation is an important epigenetic determinant in gene expression, in the maintenance of DNA integrity and stability, in chromosomal modifications, and in the development of mutations. Ethanol, a toxin that is consumed regularly, has been found to affect the methylation of DNA. In addition to its effect on DNA methylation due to folate deficiency, ethanol could directly exert its effect through its interaction with one-carbon metabolism, impairment of methyl group synthesis, and affecting the enzymes regulating the synthesis of S-adenosylmethionine, the primary methyl group donor for most biological methylation reactions. Thus, ethanol plays an important role in the pathogenesis of several diseases through its potential ability to modulate the methylation of biological molecules. This review discusses the underlying mechanism of folate malabsorption in alcoholism, the mechanism of methylation-associated silencing of genes, and how the interaction between ethanol and folate deficiency affects the methylation of genes, thereby modulating epigenome stability and the risk of cancer.
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Affiliation(s)
- Abid Hamid
- Department of Biochemistry, Postgraduate Institute of Medical Education and Research Chandigarh, India
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Said ZM, Subramanian VS, Vaziri ND, Said HM. Pyridoxine uptake by colonocytes: a specific and regulated carrier-mediated process. Am J Physiol Cell Physiol 2008; 294:C1192-7. [PMID: 18353902 DOI: 10.1152/ajpcell.00015.2008] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The water-soluble vitamin B6 (pyridoxine) is important for normal cellular functions, growth, and development. The vitamin is obtained from two exogenous sources: a dietary source, which is absorbed in the small intestine, and a bacterial source, where the vitamin is synthesized in significant quantities by the normal microflora of the large intestine. Evidence exists to suggest the bioavailability of the latter source of the vitamin, but nothing is known about the mechanism involved and its regulation. In this study, we addressed these issues using young adult mouse colonic epithelial (YAMC) cells and human colonic apical membrane vesicles (AMV) as models and using [3H]pyridoxine as the uptake substrate. The results showed the initial rate of [3H]pyridoxine uptake by YAMC cells to be 1) energy- and temperature- (but not Na-) dependent and to occur without metabolic alteration in the transported substrate; 2) saturable as a function of concentration with an apparent Km and Vmax of 2.1 +/- 0.5 muM and 53.4 +/- 4.3 pmol.mg protein(-1).3 min(-1), respectively; 3) cis-inhibited by unlabeled pyridoxine and its structural analogs, but not by the unrelated compounds theophylline, penicillamine, and isoniazid; 4) trans-stimulated by unlabeled pyridoxine; 5) amiloride sensitive; and 6) regulated by extracellular and intracellular factors. Uptake of pyridoxine by native human colonic AMV was also found to involve a carrier-mediated process. These studies demonstrate, for the first time, the functional existence of a specific and regulatable carrier-mediated process for pyridoxine uptake by mammalian colonocytes.
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Affiliation(s)
- Zainab M Said
- Department of Medicine and Physiology, University of California, Irvine, California, USA
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18
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Hamid A, Kaur J, Mahmood A. Evaluation of the kinetic properties of the folate transport system in intestinal absorptive epithelium during experimental ethanol ingestion. Mol Cell Biochem 2007; 304:265-71. [PMID: 17530184 DOI: 10.1007/s11010-007-9509-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2007] [Accepted: 05/03/2007] [Indexed: 12/15/2022]
Abstract
Folate plays a critical role in maintaining normal metabolic, energy, differentiation and growth status of all mammalian cells. The disturbances in body folate homeostasis such as intestinal malabsorption in alcoholism are well-known contributor to folate deficiency associated disorders. The study was sought to delineate the kinetic features of folate transport in intestinal absorptive epithelium that could highlight insights of malabsorption during alcoholism. We studied [(3)H]-folic acid transport in intestinal brush border membrane (BBM) after 3 months of ethanol administration at 1 g/kg body weight/day to rats. The results showed that the folate transport exhibited saturable kinetics and was pH, Na(+), temperature, divalent cation sensitive, besides -SH group(s) was/were found important in the folate transport system to be efficiently operative. Importantly, the decreased intestinal BBM folate transport in chronic alcoholism was associated with increased K (m) and decreased V (max) during alcoholism. In addition, S-S group status of the transporter and presence of Na(+ )at the absorptive site seems to be perturbed during ethanol ingestion. However, H(+)/folate(-) coupled transport provided the driving force for transport as pH optimum in acidic range was not altered during alcoholism. The inhibition constants of methotrexate and unlabelled folic acid revealed that the two analogues are handled differently by the folate transport system. In addition, the low activity of folate transport system during chronic ethanol exposure was associated with low RBC folate levels. Overall, these findings suggest that the deregulated folate transport kinetics might contribute to intestinal folate malabsorption in alcoholism.
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Affiliation(s)
- Abid Hamid
- Department of Biochemistry, Postgraduate Institute of Medical Education and Research, Chandigarh 160012, India
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20
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Pompei A, Cordisco L, Amaretti A, Zanoni S, Matteuzzi D, Rossi M. Folate production by bifidobacteria as a potential probiotic property. Appl Environ Microbiol 2006; 73:179-85. [PMID: 17071792 PMCID: PMC1797147 DOI: 10.1128/aem.01763-06] [Citation(s) in RCA: 190] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The ability of 76 Bifidobacterium strains to produce folate was investigated. In order to evaluate folic acid productivity, bifidobacteria were cultivated in the folate-free semisynthetic medium SM7. Most of the tested strains needed folate for growth. The production and the extent of vitamin accumulation were not a function of species but were distinctive features of individual strains. Six strains among the 17 that grew without folate produced significantly higher concentrations of vitamin (between 41 and 82 ng ml(-1)). The effects of exogenous folate and p-aminobenzoic acid (PABA) concentrations on folate production were evaluated. In contrast to most of the other strains, the folate yield of B. adolescentis MB 239 was not negatively affected by either PABA or exogenous folic acid. Folate production by B. adolescentis MB 239 was studied in the pH range of the colonic environment, and a comparison of folate production on raffinose, lactose, and fructo-oligosaccharides, which belong to three important groups of fermentable intestinal carbon sources, was established. Differences in folate biosynthesis by B. adolescentis MB 239 were not observed as a function either of the pH or of the carbon source. Fecal culture experiments demonstrated that the addition of B. adolescentis MB 239 may increase the folate concentration in the colonic environment.
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Affiliation(s)
- Anna Pompei
- Department of Pharmaceutical Sciences, University of Bologna, Bologna, Italy
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Abstract
PURPOSE OF REVIEW The molecular biology revolution has led to a significant improvement in our understanding of biological and physiological processes. Such expansion of knowledge has also covered the field of intestinal absorption of water-soluble vitamins and is the subject of this review. RECENT FINDINGS Impressive progress has been made in the understanding of the mechanisms and regulation of transport of water-soluble vitamins at the cellular and molecular levels. In addition, the 5' regulatory regions of the genes that encode a number of the involved transporters have been cloned and characterized in vitro and in vivo in transgenic mice, thus providing important information about transcriptional regulation of these events. Furthermore, confocal imaging of live intestinal epithelial cells has led to significant progress in understanding the mechanisms involved in intracellular trafficking and membrane targeting of the carrier proteins and how clinical mutations lead to interference with transport. Finally, the identification in the large intestine of efficient and specialized carrier-mediated systems that are capable of absorbing a number of the bacterially synthesized vitamins (thiamin, folate, biotin, riboflavin, pantothenic acid) has raised the possibility that this source of vitamins may play a role in regulating (fine tuning) the normal body homeostasis of these vitamins, and especially the vitamin level in the local colonocytes. SUMMARY Water-soluble vitamin absorption involves regulated and specific mechanisms. Interference with the function of these mechanisms may lead to deficiency. The large intestine is capable of absorbing water-soluble vitamins that are synthesized by the normal microflora.
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Affiliation(s)
- Hamid M Said
- University of California-School of Medicine, Irvine, California, USA.
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Abstract
Significant progress has been made in recent years toward understanding the mechanisms and regulation of intestinal absorption of water-soluble vitamins from the diet, especially those that are transported by a specialized carrier-mediated mechanism (i.e., ascorbic acid, biotin, folate, riboflavin, thiamin, and pyridoxine). The driving force involved in the uptake events and the molecular identity of the systems involved have been identified for a number of these vitamins. In addition, information about regulation of the uptake process of these micronutrients by intracellular and extracellular factors has been forthcoming. Furthermore, the 5' regulatory region of the genes that encode a number of these transporters has been characterized, thus providing information about transcriptional regulation of the transport events. Also of interest is the identification of existence of carrier-mediated mechanisms in human colonocytes that are capable of absorbing some of the vitamins that are synthesized by normal microflora of the large intestine. Although the contribution of the latter source of vitamins toward overall host nutrition is not clear and requires further investigations, it is highly likely that it does contribute toward the cellular homeostasis of these vitamins in the localized colonocytes.
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Affiliation(s)
- Hamid M Said
- University of California School of Medicine, Irvine and VA Medical Center, Long Beach, Long Beach, California 90822, USA.
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Abstract
The antifolates were the first class of antimetabolites to enter the clinics more than 50 years ago. Over the following decades, a full understanding of their mechanisms of action and chemotherapeutic potential evolved along with the mechanisms by which cells develop resistance to these drugs. These principals served as a basis for the subsequent exploration and understanding of the mechanisms of resistance to a variety of diverse antineoplastics with different cellular targets. This section describes the bases for intrinsic and acquired antifolate resistance within the context of the current understanding of the mechanisms of actions and cytotoxic determinants of these agents. This encompasses impaired drug transport into cells, augmented drug export, impaired activation of antifolates through polyglutamylation, augmented hydrolysis of antifolate polyglutamates, increased expression and mutation of target enzymes, and the augmentation of cellular tetrahydrofolate-cofactor pools in cells. This chapter also describes how these insights are being utilized to develop gene therapy approaches to protect normal bone marrow progenitor cells as a strategy to improve the efficacy of bone marrow transplantation. Finally, clinical studies are reviewed that correlate the cellular pharmacology of methotrexate with the clinical outcome in children with neoplastic diseases treated with this antifolate.
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Affiliation(s)
- Rongbao Zhao
- Departments of Medicine and Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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Said HM, Ortiz A, Subramanian VS, Neufeld EJ, Moyer MP, Dudeja PK. Mechanism of thiamine uptake by human colonocytes: studies with cultured colonic epithelial cell line NCM460. Am J Physiol Gastrointest Liver Physiol 2001; 281:G144-50. [PMID: 11408266 DOI: 10.1152/ajpgi.2001.281.1.g144] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Thiamine (vitamin B(1)) is essential for normal cellular functions and growth. Mammals cannot synthesize thiamine and thus must obtain the vitamin via intestinal absorption. The intestine is exposed to a dietary thiamine source and a bacterial source in which the vitamin is synthesized by the normal microflora of the large intestine. Very little is known about thiamine uptake in the large intestine. The aim of this study was, therefore, to address this issue. Our results with human-derived colonic epithelial NCM460 cells as a model system showed thiamine uptake to be 1) temperature- and energy dependent, 2) Na(+) independent, 3) increased with increasing buffer pH from 5 to 8 and after cell acidification but inhibited by amiloride, 4) saturable as a function of concentration, 5) inhibited by thiamine structural analogs but not by unrelated organic cations, and 6) inhibited by modulators of a Ca(2+)/calmodulin-mediated pathway. NCM460 cells and native human colonic mucosa expressed the recently cloned human thiamine transporter THTR-1 (product of the SLC19A2 gene) at both mRNA and protein levels. These results demonstrate for the first time that human NCM460 colonocytes possess a specific carrier-mediated system for thiamine uptake that appears to be under the regulation of an intracellular Ca(2+)/calmodulin-mediated pathway. It is suggested that bacterially synthesized thiamine in the large intestine may contribute to thiamine nutrition of the host, especially toward cellular nutrition of the local colonocytes.
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Affiliation(s)
- H M Said
- Department of Veterans Affairs Medical Center, Long Beach, California 90822, USA.
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Dudeja PK, Kode A, Alnounou M, Tyagi S, Torania S, Subramanian VS, Said HM. Mechanism of folate transport across the human colonic basolateral membrane. Am J Physiol Gastrointest Liver Physiol 2001; 281:G54-60. [PMID: 11408255 DOI: 10.1152/ajpgi.2001.281.1.g54] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Previous studies from our laboratory have demonstrated the existence of a folate transporter in the human colonic apical membranes. The current studies were undertaken to examine the possible presence and function of a folate carrier in the human colonic basolateral membrane vesicles (BLMV). BLMV were purified from mucosal scrapings of colons of organ donors by a Percoll-density gradient centrifugation technique, and uptake studies were performed using a rapid filtration technique. Our results on [(3)H]Pte-Glu uptake are summarized as follows: 1) uptake was sensitive to osmolarity of the incubation medium; 2) Na(+) removal from the incubation medium did not affect folate uptake into BLMV; 3) uptake was significantly increased with decreasing incubation buffer pH from 8 to 4; 4) uptake demonstrated saturation kinetics with an apparent Michaelis constant of 9.6 +/- 0.48 microM and a maximal velocity of 8.10 +/- 0.36 pmol x mg protein(-1) x 10 s(-1); 5) uptake was markedly inhibited by the structural analog methotrexate (inhibitory constant = 8.28 +/- 1.0 microM); 6) uptake into BLMV demonstrated a trans-stimulation phenomenon; 7) anion exchange inhibitors DIDS and SITS significantly inhibited folate uptake; and 8) uptake was potential-insensitive, as voltage clamping of vesicles or making them inside positive with K(+)/valinomycin failed to influence folate uptake. Western blot analysis using purified human colonic basolateral membrane preparations and specific polyclonal antibodies against the human reduced folate carrier (hRFC) has shown expression of the hRFC protein at this membrane domain. These data demonstrate the existence of a pH-dependent, DIDS-sensitive, electroneutral, carrier-mediated mechanism for folate transport across the human colonic basolateral membranes.
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Affiliation(s)
- P K Dudeja
- Department of Medicine, University of Illinois at Chicago and Westside Veterans Affairs Medical Center, Chicago, Illinois 60612, USA.
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Said HM, Chatterjee N, Haq RU, Subramanian VS, Ortiz A, Matherly LH, Sirotnak FM, Halsted C, Rubin SA. Adaptive regulation of intestinal folate uptake: effect of dietary folate deficiency. Am J Physiol Cell Physiol 2000; 279:C1889-95. [PMID: 11078704 DOI: 10.1152/ajpcell.2000.279.6.c1889] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Folate is an essential micronutrient that, in mammals, must be obtained from exogenous sources via intestinal absorption. Previous studies have characterized different aspects of the mechanism of the intestinal folate uptake process. Much less, however, is known about regulation of this process. In this study, we examined the effect of dietary folate deficiency on intestinal folate uptake using the rat as an animal model. The results showed that dietary folate deficiency leads to a significant (P < 0.01) and specific upregulation in the transepithelial transport of folic acid. The upregulation in transepithelial folate transport 1) was found to be due to an induction in carrier-mediated folate uptake across the brush-border membrane (BBM) and was mediated via a significant (P < 0.01) increase in the maximal velocity but not the apparent Michaelis constant of the uptake process, 2) was associated with a marked increase in the steady-state mRNA level of reduced folate carrier-1 and in the level of the expressed protein at the intestinal BBM, and 3) was associated with a marked (>10-fold) increase in the activity of the intestinal BBM form of folate hydrolase. Results of this study demonstrate, for the first time, that dietary folate deficiency leads to a marked upregulation in intestinal folate uptake and in the activity of folate hydrolase. Furthermore, the upregulation in folate uptake is associated with an increase in mRNA and protein levels of folate carrier, suggesting possible involvement of a transcriptional regulatory mechanism(s) in the upregulation.
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Affiliation(s)
- H M Said
- University of California Irvine-Long Beach Veterans Affairs Medical Program, Long Beach 90822, USA.
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Said HM, Ortiz A, Moyer MP, Yanagawa N. Riboflavin uptake by human-derived colonic epithelial NCM460 cells. Am J Physiol Cell Physiol 2000; 278:C270-6. [PMID: 10666022 DOI: 10.1152/ajpcell.2000.278.2.c270] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Normal microflora of the large intestine synthesize a number of water-soluble vitamins including riboflavin (RF). Recent studies have shown that colonic epithelial cells possess an efficient carrier-mediated mechanism for absorbing some of these micronutrients. The aim of the present study was to determine whether colonic cells also possess a carrier-mediated mechanism for RF uptake and, if so, to characterize this mechanism and study its cellular regulation. Confluent monolayers of the human-derived nontransformed colonic epithelial cells NCM460 and [(3)H]RF were used in the study. Uptake of RF was found to be 1) appreciable and temperature and energy dependent; 2) Na(+) independent; 3) saturable as a function of concentration with an apparent K(m) of 0.14 microM and V(max) of 3.29 pmol x mg protein(-1) x 3 min(-1); 4) inhibited by the structural analogs lumiflavin and lumichrome (K(i) of 1.8 and 14.1 microM, respectively) but not by the unrelated biotin; 5) inhibited in a competitive manner by the membrane transport inhibitor amiloride (K(i) = 0.86 mM) but not by furosemide, DIDS, or probenecid; 6) adaptively regulated by extracellular RF levels with a significant and specific upregulation and downregulation in RF uptake in RF-deficient and oversupplemented conditions, respectively; and 7) modulated by an intracellular Ca(2+)/calmodulin-mediated pathway. These studies demonstrate for the first time the existence of a specialized carrier-mediated mechanism for RF uptake in an in vitro cellular model system of human colonocytes. This mechanism appears to be regulated by extracellular substrate level and by an intracellular Ca(2+)/calmodulin-mediated pathway. It is suggested that the identified transport system may be involved in the absorption of bacterially synthesized RF in the large intestine and that this source of RF may contribute toward RF homeostasis, especially that of colonocytes.
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Affiliation(s)
- H M Said
- Veterans Affairs Medical Center, Long Beach, CA 90822, USA.
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