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Farrell CC, Khanna S, Hoque MT, Plaga A, Basset N, Syed I, Biouss G, Aufreiter S, Marcon N, Bendayan R, Kim YI, O'Connor DL. Low-dose daily folic acid (400 μg) supplementation does not affect regulation of folate transporters found present throughout the terminal ileum and colon of humans: a randomized clinical trial. Am J Clin Nutr 2024; 119:809-820. [PMID: 38157986 DOI: 10.1016/j.ajcnut.2023.12.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 11/23/2023] [Accepted: 12/26/2023] [Indexed: 01/03/2024] Open
Abstract
BACKGROUND Folic acid supplementation during the periconceptional period reduces the risk of neural tube defects in infants, but concern over chronic folic acid exposure remains. An improved understanding of folate absorption may clarify potential risks. Folate transporters have been characterized in the small intestine, but less so in the colon of healthy, free-living humans. The impact of folic acid fortification or supplementation on regulation of these transporters along the intestinal tract is unknown. OBJECTIVE The objective was to characterize expression of folate transporters/receptor (FT/R) and folate hydrolase, glutamate carboxypeptidase II (GCPII), from the terminal ileum and throughout the colon of adults and assess the impact of supplemental folic acid. METHODS In this 16-wk open-labeled randomized clinical trial, adults consumed a low folic acid-containing diet, a folate-free multivitamin, and either a 400 μg folic acid supplement or no folic acid supplement. Dietary intakes and blood were assessed at baseline, 8 wk, and 16 wk (time of colonoscopy). Messenger RNA (mRNA) expression and protein expression of FT/R and GCPII were assessed in the terminal ileum, cecum, and ascending and descending colon. RESULTS Among 24 randomly assigned subjects, no differences in dietary folate intake or blood folate were observed at baseline. Mean ± SD red blood cell folate at 16 wk was 1765 ± 426 and 911 ± 242 nmol/L in the 400 and 0 μg folic acid group, respectively (P < 0.0001). Reduced folate carrier, proton-coupled folate transporter, and folate-receptor alpha expression were detected in the terminal ileum and colon, as were efflux transporters of breast cancer resistance protein and multidrug resistance protein-3. Other than a higher mRNA expression of FR-alpha and GCPII in the 400 μg supplement group in the ascending colon, no treatment differences were observed (P < 0.02). CONCLUSIONS Folate transporters are present throughout the terminal ileum and colon; there is little evidence that a low dose of folic acid supplementation affects colonic absorption. This trial was registered at clinicaltrials.gov as NCT03421483.
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Affiliation(s)
- Colleen C Farrell
- Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada; Translational Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Siya Khanna
- Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada; Translational Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Md Tozammel Hoque
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Aneta Plaga
- Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada; Translational Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Nancy Basset
- Division of Gastroenterology, Department of Medicine, St. Michael's Hospital, Toronto, Ontario, Canada
| | - Ishba Syed
- Division of Gastroenterology, Department of Medicine, St. Michael's Hospital, Toronto, Ontario, Canada
| | - George Biouss
- Translational Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada; Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Susanne Aufreiter
- Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada; Translational Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Norman Marcon
- Division of Gastroenterology, Department of Medicine, St. Michael's Hospital, Toronto, Ontario, Canada
| | - Reina Bendayan
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Young-In Kim
- Division of Gastroenterology, Department of Medicine, St. Michael's Hospital, Toronto, Ontario, Canada; Keenan Research Centre for Biomedical Science of St. Michael's Hospital, Toronto, Ontario, Canada
| | - Deborah L O'Connor
- Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada; Translational Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada.
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Sharma J, Krupenko SA. Folate pathways mediating the effects of ethanol in tumorigenesis. Chem Biol Interact 2020; 324:109091. [PMID: 32283069 DOI: 10.1016/j.cbi.2020.109091] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 04/02/2020] [Indexed: 02/08/2023]
Abstract
Folate and alcohol are dietary factors affecting the risk of cancer development in humans. The interaction between folate status and alcohol consumption in carcinogenesis involves multiple mechanisms. Alcoholism is typically associated with folate deficiency due to reduced dietary folate intake. Heavy alcohol consumption also decreases folate absorption, enhances urinary folate excretion and inhibits enzymes pivotal for one-carbon metabolism. While folate metabolism is involved in several key biochemical pathways, aberrant DNA methylation, due to the deficiency of methyl donors, is considered as a common downstream target of the folate-mediated effects of ethanol. The negative effects of low intakes of nutrients that provide dietary methyl groups, with high intakes of alcohol are additive in general. For example, low methionine, low-folate diets coupled with alcohol consumption could increase the risk for colorectal cancer in men. To counteract the negative effects of alcohol consumption, increased intake of nutrients, such as folate, providing dietary methyl groups is generally recommended. Here mechanisms involving dietary folate and folate metabolism in cancer disease, as well as links between these mechanisms and alcohol effects, are discussed. These mechanisms include direct effects on folate pathways and indirect mediation by oxidative stress, hypoxia, and microRNAs.
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Affiliation(s)
- Jaspreet Sharma
- Nutrition Research Institute and Department of Nutrition, University of North Carolina, Chapel Hill, USA
| | - Sergey A Krupenko
- Nutrition Research Institute and Department of Nutrition, University of North Carolina, Chapel Hill, USA; Department of Nutrition, University of North Carolina, Chapel Hill, USA.
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Alam C, Hoque MT, Finnell RH, Goldman ID, Bendayan R. Regulation of Reduced Folate Carrier (RFC) by Vitamin D Receptor at the Blood-Brain Barrier. Mol Pharm 2017; 14:3848-3858. [PMID: 28885847 DOI: 10.1021/acs.molpharmaceut.7b00572] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Folates are essential for brain development and function. Folate transport in mammalian tissues is mediated by three major folate transport systems, i.e., reduced folate carrier (RFC), proton-coupled folate transporter (PCFT), and folate receptor alpha (FRα), known to be regulated by ligand-activated nuclear receptors, such as vitamin D receptor (VDR). Folate uptake at the choroid plexus, which requires the actions of both FRα and PCFT, is critical to cerebral folate delivery. Inactivating FRα or PCFT mutations cause severe cerebral folate deficiency resulting in early childhood neurodegeneration. The objective of this study was to investigate the role of RFC in folate uptake at the level of the blood-brain barrier (BBB) and its potential regulation by VDR. We detected robust expression of RFC in different in vitro BBB model systems, particularly in immortalized cultures of human cerebral microvascular endothelial cells (hCMEC/D3) and isolated mouse brain capillaries. [3H]-methotrexate uptake by hCMEC/D3 cells at pH 7.4 was inhibited by PT523 and pemetrexed, antifolates with high affinity for RFC. We also showed that activation of VDR through calcitriol (1,25-dihydroxyvitamin D3) exposure up-regulates RFC mRNA and protein expression as well as function in hCMEC/D3 cells and isolated mouse brain capillaries. We further demonstrated that RFC expression could be down-regulated by VDR-targeting siRNA, further confirming the role of VDR in the direct regulation of this folate transporter. Together, these data suggest that augmenting RFC functional expression could constitute a novel strategy for enhancing brain folate delivery for the treatment of neurometabolic disorders caused by loss of FRα or PCFT function.
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Affiliation(s)
- Camille Alam
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto , Toronto, Ontario M5S 3M2, Canada
| | - Md Tozammel Hoque
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto , Toronto, Ontario M5S 3M2, Canada
| | - Richard H Finnell
- Departments of Molecular and Cellular Biology and Medicine, Baylor College of Medicine , Houston, Texas 77030, United States
| | - I David Goldman
- Department of Molecular Pharmacology, Albert Einstein College of Medicine , Bronx, New York 10461, United States
| | - Reina Bendayan
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto , Toronto, Ontario M5S 3M2, Canada
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Pérez-Solis MA, Maya-Nuñez G, Casas-González P, Olivares A, Aguilar-Rojas A. Effects of the lifestyle habits in breast cancer transcriptional regulation. Cancer Cell Int 2016; 16:7. [PMID: 26877711 PMCID: PMC4752785 DOI: 10.1186/s12935-016-0284-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 02/03/2016] [Indexed: 12/31/2022] Open
Abstract
Through research carried out in the last 25 years about the breast cancer etiology, it has been possible to estimate that less than 10 % of patients who are diagnosed with the condition are carriers of some germline or somatic mutation. The clinical reports of breast cancer patients with healthy twins and the development of disease in women without high penetrance mutations detected, warn the participation more factors in the transformation process. The high incidence of mammary adenocarcinoma in the modern woman and the urgent need for new methods of prevention and early detection have demanded more information about the role that environment and lifestyle have on the transformation of mammary gland epithelial cells. Obesity, alcoholism and smoking are factors that have shown a close correlation with the risk of developing breast cancer. And although these conditions affect different cell regulation levels, the study of its effects in the mechanisms of transcriptional and epigenetic regulation is considered critical for a better understanding of the loss of identity of epithelial cells during carcinogenesis of this tissue. The main objective of this review was to establish the importance of changes occurring to transcriptional level in the mammary gland as a consequence of acute or chronic exposure to harmful products such as obesity-causing foods, ethanol and cigarette smoke components. At analyze the main studies related to topic, it has concluded that the understanding of effects caused by the lifestyle factors in performance of the transcriptional mechanisms that determine gene expression of the mammary gland epithelial cells, may help explain the development of this disease in women without genetic propensity and different phenotypic manifestations of this cancer type.
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Affiliation(s)
- Marco Allán Pérez-Solis
- Research Unit in Reproductive Medicine, Hospital de Ginecobstetricia “Luis Castelazo Ayala”, Instituto Mexicano del Seguro Social, No. 289 Río Magdalena, Tizapan San Angel, 01090 Mexico, DF Mexico
| | - Guadalupe Maya-Nuñez
- Research Unit in Reproductive Medicine, Hospital de Ginecobstetricia “Luis Castelazo Ayala”, Instituto Mexicano del Seguro Social, No. 289 Río Magdalena, Tizapan San Angel, 01090 Mexico, DF Mexico
| | - Patricia Casas-González
- Research Unit in Reproductive Medicine, Hospital de Ginecobstetricia “Luis Castelazo Ayala”, Instituto Mexicano del Seguro Social, No. 289 Río Magdalena, Tizapan San Angel, 01090 Mexico, DF Mexico
| | - Aleida Olivares
- Research Unit in Reproductive Medicine, Hospital de Ginecobstetricia “Luis Castelazo Ayala”, Instituto Mexicano del Seguro Social, No. 289 Río Magdalena, Tizapan San Angel, 01090 Mexico, DF Mexico
| | - Arturo Aguilar-Rojas
- Research Unit in Reproductive Medicine, Hospital de Ginecobstetricia “Luis Castelazo Ayala”, Instituto Mexicano del Seguro Social, No. 289 Río Magdalena, Tizapan San Angel, 01090 Mexico, DF Mexico
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Increased synthesis of folate transporters regulates folate transport in conditions of ethanol exposure and folate deficiency. Mol Cell Biochem 2015; 411:151-60. [PMID: 26433955 DOI: 10.1007/s11010-015-2577-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 09/26/2015] [Indexed: 01/31/2023]
Abstract
Excessive alcohol consumption and dietary folate inadequacy are the main contributors leading to folate deficiency (FD). The present study was planned to study regulation of folate transport in conditions of FD and ethanol exposure in human embryonic kidney cell line. Also, the reversible nature of effects mediated by ethanol exposure and FD was determined by folate repletion and ethanol removal. For ethanol treatment, HEK293 cells were grown in medium containing 100 mM ethanol, and after treatment, one group of cells was shifted on medium that was free from ethanol. For FD treatment, cells were grown in folate-deficient medium followed by shifting of one group of cells on folate containing medium. FD as well as ethanol exposure resulted in an increase in folate uptake which was due to an increase in expression of folate transporters, i.e., reduced folate carrier, proton-coupled folate transporter, and folate receptor, both at the mRNA and protein level. The effects mediated by ethanol exposure and FD were reversible on removal of treatment. Promoter region methylation of folate transporters remained unaffected after FD and ethanol exposure. As far as transcription rate of folate transporters is concerned, an increase in rate of synthesis was observed in both ethanol exposure and FD conditions. Additionally, mRNA life of folate transporters was observed to be reduced by FD. An increased expression of folate transporters under ethanol exposure and FD conditions can be attributed to enhanced rate of synthesis of folate transporters.
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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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Thakur S, Kaur J. Regulation at multiple levels control the expression of folate transporters in liver cells in conditions of ethanol exposure and folate deficiency. Biofactors 2015; 41:232-41. [PMID: 26154406 DOI: 10.1002/biof.1217] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2015] [Accepted: 05/27/2015] [Indexed: 01/01/2023]
Abstract
Complex regulatory mechanisms control the expression of folate transporters within cells. Liver is the primary reserve of the folate stores within the body. As excessive alcohol consumption or inefficient dietary folate intake are known to create folate deficiency, so therefore the current study was designed to explore various regulatory mechanisms controlling the expression of folate transport in liver cells in conditions of ethanol exposure and folate deficiency. In order to see whether the effects mediated by the treatments are reversible or not, ethanol removal, and folate repletion was done after ethanol exposure and folate deficiency treatment respectively. Folate deficiency resulted an increase, whereas ethanol treatment decreased the folic acid uptake within the cells. The alterations in folic acid uptake were in agreement with the observed changes in the expression of folate transporters. Ethanol exposure resulted an increase in promoter methylation of reduced folate carrier; however, folate deficiency had no effect. The effects produced by ethanol exposure and folate deficiency were found to be reversible in nature as depicted in case of ethanol removal and folate repletion group. Rate of synthesis of folate transporters was found to be increased whereas half lives of mRNA of folate transporters was found to be decreased on folate deficiency treatment and reverse was the case on ethanol treatment. Overall, alteration in the expression of folate transporters under ethanol exposure and folate deficient conditions can be attributed to those regulatory mechanisms which work at the mRNA level.
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Affiliation(s)
- Shilpa Thakur
- 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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Reduced expression of folate transporters in kidney of a rat model of folate oversupplementation. GENES AND NUTRITION 2013; 9:369. [PMID: 24306960 DOI: 10.1007/s12263-013-0369-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 11/12/2013] [Indexed: 12/29/2022]
Abstract
Folic acid is the key one-carbon donor required for de novo nucleotide and methionine synthesis. Its deficiency is associated with megaloblastic anemia, cancer and various complications of pregnancy. However, its supplementation results in reduction of neural tube defects and prevention of several types of cancer. The intake of folic acid from fortified food together with the use of nutritional supplements creates a state of folate oversupplementation. Fortification of foods is occurring worldwide with little knowledge of the potential safety and physiologic consequences of intake of such high doses of folic acid. So, we planned to examine the effects of acute and chronic folate oversupplementation on the physiology of renal folate transport in rats. Male Wistar rats were procured and divided into two groups. Rats in group I were given semisynthetic diets containing 2 mg folic acid/kg diet (control) and those in group II were given folate-oversupplemented rat diet, i.e., 20 mg folic acid/kg diet (oversupplemented). Six animals from group I and group II received the treatment for 10 days (acute treatment) and remaining six for 60 days (chronic treatment). In acute folate-oversupplemented rats, 5-[(14)C]-methyltetrahydrofolate uptake was found to be significantly reduced, as compared to chronic folate-oversupplemented and control rats. This reduction in uptake was associated with a significant decrease in the mRNA and protein levels of the folate transporters. Results of the present investigation showed that acute oversupplementation led to a specific and significant down-regulation of renal folate uptake process mediated via transcriptional and translational regulatory mechanism(s).
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Wani NA, Thakur S, Najar RA, Nada R, Khanduja KL, Kaur J. Mechanistic insights of intestinal absorption and renal conservation of folate in chronic alcoholism. Alcohol 2013; 47:121-30. [PMID: 23267781 DOI: 10.1016/j.alcohol.2012.11.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2011] [Revised: 10/18/2012] [Accepted: 11/27/2012] [Indexed: 01/01/2023]
Abstract
Folate mediated one-carbon metabolism is of fundamental importance for various cellular processes, including DNA synthesis and methylation of biological molecules. Due to the exogenous requirement of folate in mammals, there exists a well developed epithelial folate transport system for regulation of normal folate homeostasis. The intestinal and renal folate uptake is tightly and diversely regulated and disturbances in folate homeostasis like in alcoholism have pathological consequences. The study was sought to delineate the regulatory mechanism of folate uptake in intestine and reabsorption in renal tubular cells that could evaluate insights of malabsorption during alcoholism. The folate transporters PCFT and RFC were found to be associated with lipid rafts of membrane surfaces in intestine and kidney. Importantly, the observed lower intestinal and renal folate uptake was associated with decreased levels of folate transporter viz. PCFT and RFC in lipid rafts of intestinal and renal membrane surfaces. The decreased association of folate transporters in lipid rafts was associated with decreased protein and mRNA levels. In addition, immunohistochemical studies showed that alcoholic conditions deranged that localization of PCFT and RFC. These findings could explain the possible mechanistic insights that may result in folate malabsorption during alcoholism.
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Farkas SA, Böttiger AK, Isaksson HS, Finnell RH, Ren A, Nilsson TK. Epigenetic alterations in folate transport genes in placental tissue from fetuses with neural tube defects and in leukocytes from subjects with hyperhomocysteinemia. Epigenetics 2013; 8:303-16. [PMID: 23417011 PMCID: PMC3669122 DOI: 10.4161/epi.23988] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The objectives of this study were to identify tissue-specific differentially methylated regions (T-DMR’s) in the folate transport genes in placental tissue compared with leukocytes, and from placental tissues obtained from normal infants or with neural tube defects (NTDs). Using pyrosequencing, we developed methylation assays for the CpG islands (CGIs) and the CGI shore regions of the folate receptor α (FOLR1), proton-coupled folate transporter (PCFT) and reduced folate carrier 1 (RFC1) genes. The T-DMRs differed in location for each gene and the difference in methylation ranged between 2 and 54%. A higher T-DMR methylated fraction was associated with a lower mRNA level of the FOLR1 and RFC1 genes. Methylation fractions differed according to RFC1 80G > A genotype in the NTD cases and in leukocytes from subjects with high total plasma homocysteine (tHcy). There were no differences in methylated fraction of folate transporter genes between NTD cases and controls. We suggest that T-DMRs participate in the regulation of expression of the FOLR1 and RFC1 genes, that the RFC1 80G > A polymorphism exerts a gene-nutrition interaction on DNA methylation in the RFC1 gene, and that this interaction appears to be most prominent in NTD-affected births and in subjects with high tHcy concentrations.
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Affiliation(s)
- Sanja A Farkas
- Department of Laboratory Medicine, Örebro University Hospital, Örebro, Sweden.
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Abstract
Epigenetic medicine is still in its infancy. To date, only a handful of diseases have documented epigenetic correlates upstream of gene regulation including cancer, developmental syndromes and late-onset diseases. The finding that epigenetic markers are dynamic and heterogeneous at tissue and cellular levels, combined with recent identification of a new form of functionally distinct DNA methylation has opened a wider window for investigators to pry into the epigenetic world. It is anticipated that many diseases will be elucidated through this epigenetic inquiry. In this review, we discuss the normal course of DNA methylation during development, taking alcohol as a demonstrator of the epigenetic impact of environmental factors in disease etiology, particularly the growth retardation and neurodevelopmental deficits of fetal alcohol spectrum disorders.
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Affiliation(s)
- Marisol Resendiz
- Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Yuanyuan Chen
- Department of Anatomy & Cell Biology, MS508, Indiana University School Medicine, Indianapolis, IN 46202, USA
| | - Nail C Öztürk
- Department of Anatomy & Cell Biology, MS508, Indiana University School Medicine, Indianapolis, IN 46202, USA
- Department of Anatomy, Mersin University School of Medicine, Turkey
| | - Feng C Zhou
- Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Department of Anatomy & Cell Biology, MS508, Indiana University School Medicine, Indianapolis, IN 46202, USA
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Wani NA, Kaur J. Adaptive transport of folic acid across renal epithelia in folate-deficient rats. J Physiol Sci 2012; 62:461-8. [PMID: 22865158 PMCID: PMC10717754 DOI: 10.1007/s12576-012-0223-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 07/16/2012] [Indexed: 01/01/2023]
Abstract
Folate (vitamin B(9)) is an essential vitamin for a wide spectrum of biochemical reactions; however, unlike bacteria and plants, mammals are devoid of folate biosynthesis and thus must obtain this cofactor from exogenous sources. The activities of folate transporters on the kidneys play an important role in conserving folate excretion and reabsorption across the apical membrane of the renal proximal tubules. The different transport system activities may become identifiable in response to external stimuli, such as folate availability and exposure to chemotherapeutic agents. We have explored the effect of folate deficiency on the activity and expression of folate transporters in rat kidneys. Wistar rats were fed a folate-containing diet (2 mg folic acid kg(-1) diet) or a folic acid-free diet over a 3-month period, and mechanisms of folate transport were studied in renal brush border membrane vesicles and basolateral membrane vesicles. The renal folate uptake process is saturable and pH dependent, and it involves the folate receptor and reduced folate carrier (RFC) systems and possibly the proton coupled folate transporter (PCFT) system. We found that folate deficiency increased the renal brush border membrane and basolateral folate uptake by increasing the number of transporter molecules. The observed up-regulation of mRNA expression was also associated with a significant increase in RFC and PCFT expression at the protein level.
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Affiliation(s)
- Nissar Ahmad Wani
- Department of Biochemistry, Postgraduate Institute of Medical Education and Research, Chandigarh, 160 012 India
| | - Jyotdeep Kaur
- Department of Biochemistry, Postgraduate Institute of Medical Education and Research, Chandigarh, 160 012 India
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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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