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Short SP, Pilat JM, Barrett CW, Reddy VK, Haberman Y, Hendren JR, Marsh BJ, Keating CE, Motley AK, Hill KE, Zemper AE, Washington MK, Shi C, Chen X, Wilson KT, Hyams JS, Denson LA, Burk RF, Rosen MJ, Williams CS. Colonic Epithelial-Derived Selenoprotein P Is the Source for Antioxidant-Mediated Protection in Colitis-Associated Cancer. Gastroenterology 2021; 160:1694-1708.e3. [PMID: 33388316 PMCID: PMC8035252 DOI: 10.1053/j.gastro.2020.12.059] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 12/07/2020] [Accepted: 12/23/2020] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS Patients with inflammatory bowel disease (IBD) demonstrate nutritional selenium deficiencies and are at greater risk of developing colon cancer. Previously, we determined that global reduction of the secreted antioxidant selenium-containing protein, selenoprotein P (SELENOP), substantially increased tumor development in an experimental colitis-associated cancer (CAC) model. We next sought to delineate tissue-specific contributions of SELENOP to intestinal inflammatory carcinogenesis and define clinical context. METHODS Selenop floxed mice crossed with Cre driver lines to delete Selenop from the liver, myeloid lineages, or intestinal epithelium were placed on an azoxymethane/dextran sodium sulfate experimental CAC protocol. SELENOP loss was assessed in human ulcerative colitis (UC) organoids, and expression was queried in human and adult UC samples. RESULTS Although large sources of SELENOP, both liver- and myeloid-specific Selenop deletion failed to modify azoxymethane/dextran sodium sulfate-mediated tumorigenesis. Instead, epithelial-specific deletion increased CAC tumorigenesis, likely due to elevated oxidative stress with a resulting increase in genomic instability and augmented tumor initiation. SELENOP was down-regulated in UC colon biopsies and levels were inversely correlated with endoscopic disease severity and tissue S100A8 (calprotectin) gene expression. CONCLUSIONS Although global selenium status is typically assessed by measuring liver-derived plasma SELENOP levels, our results indicate that the peripheral SELENOP pool is dispensable for CAC. Colonic epithelial SELENOP is the main contributor to local antioxidant capabilities. Thus, colonic SELENOP is the most informative means to assess selenium levels and activity in IBD patients and may serve as a novel biomarker for UC disease severity and identify patients most predisposed to CAC development.
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Affiliation(s)
- Sarah P Short
- Department of Medicine, Division of Gastroenterology, Vanderbilt University Medical Center, Nashville, Tennessee; Program in Cancer Biology, Vanderbilt University, Nashville, Tennessee; Center for Mucosal Inflammation and Cancer, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Jennifer M Pilat
- Department of Medicine, Division of Gastroenterology, Vanderbilt University Medical Center, Nashville, Tennessee; Program in Cancer Biology, Vanderbilt University, Nashville, Tennessee
| | - Caitlyn W Barrett
- Department of Medicine, Division of Gastroenterology, Vanderbilt University Medical Center, Nashville, Tennessee; Program in Cancer Biology, Vanderbilt University, Nashville, Tennessee
| | - Vishruth K Reddy
- Department of Medicine, Division of Gastroenterology, Vanderbilt University Medical Center, Nashville, Tennessee; Program in Cancer Biology, Vanderbilt University, Nashville, Tennessee; Department of Radiation Oncology, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Yael Haberman
- Division of Gastroenterology, Hepatology and Nutrition, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio; Sheba Medical Center, Tel Hashomer, affiliated with the Tel Aviv University, Tel Aviv, Israel
| | - Jared R Hendren
- Department of Medicine, Division of Gastroenterology, Vanderbilt University Medical Center, Nashville, Tennessee; School of Medicine, Southern Illinois University, Springfield, Illinois
| | - Benjamin J Marsh
- Department of Medicine, Division of Gastroenterology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Cody E Keating
- Department of Medicine, Division of Gastroenterology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Amy K Motley
- Department of Medicine, Division of Gastroenterology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Kristina E Hill
- Department of Medicine, Division of Gastroenterology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Anne E Zemper
- Department of Biology, University of Oregon, Eugene, Oregon; Institute of Molecular Biology, University of Oregon, Eugene, Oregon
| | - M Kay Washington
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Chanjuan Shi
- Department of Pathology, Duke University School of Medicine, Durham, North Carolina
| | - Xi Chen
- Department of Public Health Sciences and the Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, Florida
| | - Keith T Wilson
- Department of Medicine, Division of Gastroenterology, Vanderbilt University Medical Center, Nashville, Tennessee; Program in Cancer Biology, Vanderbilt University, Nashville, Tennessee; Center for Mucosal Inflammation and Cancer, Vanderbilt University Medical Center, Nashville, Tennessee; Veterans Affairs Tennessee Valley Health Care System, Nashville, Tennessee; Vanderbilt Ingram Cancer Center, Nashville, Tennessee
| | - Jeffrey S Hyams
- Connecticut Children's Medical Center, Hartford, Connecticut
| | - Lee A Denson
- Division of Gastroenterology, Hepatology and Nutrition, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Raymond F Burk
- Department of Medicine, Division of Gastroenterology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Michael J Rosen
- Division of Gastroenterology, Hepatology and Nutrition, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Christopher S Williams
- Department of Medicine, Division of Gastroenterology, Vanderbilt University Medical Center, Nashville, Tennessee; Program in Cancer Biology, Vanderbilt University, Nashville, Tennessee; Center for Mucosal Inflammation and Cancer, Vanderbilt University Medical Center, Nashville, Tennessee; Veterans Affairs Tennessee Valley Health Care System, Nashville, Tennessee; Vanderbilt Ingram Cancer Center, Nashville, Tennessee.
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Scoville EA, Allaman MM, Adams DW, Motley AK, Peyton SC, Ferguson SL, Horst SN, Williams CS, Beaulieu DB, Schwartz DA, Wilson KT, Coburn LA. Serum Polyunsaturated Fatty Acids Correlate with Serum Cytokines and Clinical Disease Activity in Crohn's Disease. Sci Rep 2019; 9:2882. [PMID: 30814550 PMCID: PMC6393448 DOI: 10.1038/s41598-019-39232-z] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 01/18/2019] [Indexed: 12/19/2022] Open
Abstract
Crohn’s disease (CD) has been associated with an increased consumption of n-6 polyunsaturated fatty acid (PUFA), while greater intake of n-3 PUFA has been associated with a reduced risk. We sought to investigate serum fatty acid composition in CD, and associations of fatty acids with disease activity, cytokines, and adipokines. Serum was prospectively collected from 116 CD subjects and 27 non-IBD controls. Clinical disease activity was assessed by the Harvey Bradshaw Index (HBI). Serum fatty acids were measured by gas chromatography. Serum cytokines and adipokines were measured by Luminex assay. Dietary histories were obtained from a subset of patients. Nine serum cytokines and adipokines were increased in CD versus controls. CD subjects had increased percentage serum monounsaturated fatty acids (MUFA), dihomo-gamma linolenic acid (DGLA), eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and oleic acid, but decreased arachidonic acid (AA) versus controls. The % total n-3 fatty acids and % EPA directly correlated with pro-inflammatory cytokine levels and HBI, whereas the % total n-6 fatty acids were inversely correlated with pro-inflammatory cytokine levels and HBI. CD subjects had increased caloric intake versus controls, but no alterations in total fat or PUFA intake. We found differences in serum fatty acids, most notably PUFA, in CD that correlated both with clinical disease activity and inflammatory cytokines. Our findings indicate that altered fatty acid metabolism or utilization is present in CD and is related to disease activity.
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Affiliation(s)
- Elizabeth A Scoville
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Margaret M Allaman
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Dawn W Adams
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.,Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN, USA
| | - Amy K Motley
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Shannon C Peyton
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Sarah L Ferguson
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Sara N Horst
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Christopher S Williams
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.,Vanderbilt Center for Mucosal Inflammation and Cancer, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.,Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN, USA.,Vanderbilt Center for Stem Cell Biology, Vanderbilt University Medical Center, Nashville, TN, USA.,Vanderbilt Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Dawn B Beaulieu
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - David A Schwartz
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Keith T Wilson
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.,Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA.,Vanderbilt Center for Mucosal Inflammation and Cancer, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.,Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN, USA.,Vanderbilt Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Lori A Coburn
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA. .,Vanderbilt Center for Mucosal Inflammation and Cancer, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA. .,Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN, USA.
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Scoville EA, Allaman MM, Brown CT, Motley AK, Horst SN, Williams CS, Koyama T, Zhao Z, Adams DW, Beaulieu DB, Schwartz DA, Wilson KT, Coburn LA. Alterations in Lipid, Amino Acid, and Energy Metabolism Distinguish Crohn's Disease from Ulcerative Colitis and Control Subjects by Serum Metabolomic Profiling. Metabolomics 2018; 14:17. [PMID: 29681789 PMCID: PMC5907923 DOI: 10.1007/s11306-017-1311-y] [Citation(s) in RCA: 107] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
INTRODUCTION Biomarkers are needed in inflammatory bowel disease (IBD) to help define disease activity and identify underlying pathogenic mechanisms. We hypothesized that serum metabolomics, which produces unique metabolite profiles, can aid in this search. OBJECTIVES The aim of this study was to characterize serum metabolomic profiles in patients with IBD, and to assess for differences between patients with ulcerative colitis (UC), Crohn's disease (CD), and non- IBD subjects. METHODS Serum samples from 20 UC, 20 CD, and 20 non-IBD control subjects were obtained along with patient characteristics, including medication use and clinical disease activity. Non-targeted metabolomic profiling was performed using ultra-high performance liquid chromatography/mass spectrometry (UPLC-MS/MS) optimized for basic or acidic species and hydrophilic interaction liquid chromatography (HILIC/UPLC-MS/MS). RESULTS In total, 671 metabolites were identified. Comparing IBD and control subjects revealed 173 significantly altered metabolites (27 increased and 146 decreased). The majority of the alterations occurred in lipid-, amino acid-, and energy-related metabolites. Comparing only CD and control subjects revealed 286 significantly altered metabolites (54 increased and 232 decreased), whereas comparing UC and control subjects revealed only 5 significantly altered metabolites (all decreased). Hierarchal clustering using significant metabolites separated CD from UC and control subjects. CONCLUSIONS We demonstrate that a number of lipid-, amino acid-, and tricarboxylic acid (TCA) cycle- related metabolites were significantly altered in IBD patients, more specifically in CD. Therefore, alterations in lipid and amino acid metabolism and energy homeostasis may play a key role in the pathogenesis of CD.
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Affiliation(s)
- Elizabeth A Scoville
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Ave., 1030C MRB IV, Nashville, TN, 37232, USA
| | - Margaret M Allaman
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Ave., 1030C MRB IV, Nashville, TN, 37232, USA
| | - Caroline T Brown
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Ave., 1030C MRB IV, Nashville, TN, 37232, USA
| | - Amy K Motley
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Ave., 1030C MRB IV, Nashville, TN, 37232, USA
| | - Sara N Horst
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Ave., 1030C MRB IV, Nashville, TN, 37232, USA
| | - Christopher S Williams
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Ave., 1030C MRB IV, Nashville, TN, 37232, USA
- Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, TN, USA
- Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN, USA
| | - Tatsuki Koyama
- Department of Biostatistics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Zhiguo Zhao
- Department of Biostatistics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Dawn W Adams
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Ave., 1030C MRB IV, Nashville, TN, 37232, USA
- Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN, USA
| | - Dawn B Beaulieu
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Ave., 1030C MRB IV, Nashville, TN, 37232, USA
| | - David A Schwartz
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Ave., 1030C MRB IV, Nashville, TN, 37232, USA
| | - Keith T Wilson
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Ave., 1030C MRB IV, Nashville, TN, 37232, USA
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Center for Mucosal Inflammation and Cancer, Nashville, TN, USA
- Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN, USA
| | - Lori A Coburn
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Ave., 1030C MRB IV, Nashville, TN, 37232, USA.
- Vanderbilt Center for Mucosal Inflammation and Cancer, Nashville, TN, USA.
- Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN, USA.
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Burk RF, Hill KE, Motley AK, Byrne DW, Norsworthy BK. Selenium deficiency occurs in some patients with moderate-to-severe cirrhosis and can be corrected by administration of selenate but not selenomethionine: a randomized controlled trial. Am J Clin Nutr 2015; 102:1126-33. [PMID: 26468123 PMCID: PMC4625587 DOI: 10.3945/ajcn.115.110932] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 09/10/2015] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Selenomethionine, which is the principal dietary form of selenium, is metabolized by the liver to selenide, which is the form of the element required for the synthesis of selenoproteins. The liver synthesizes selenium-rich selenoprotein P (SEPP1) and secretes it into the plasma to supply extrahepatic tissues with selenium. OBJECTIVES We conducted a randomized controlled trial to determine whether cirrhosis is associated with functional selenium deficiency (the lack of selenium for the process of selenoprotein synthesis even though selenium intake is not limited) and, if it is, whether the deficiency is associated with impairment of selenomethionine metabolism. DESIGN Patients with Child-Pugh (C-P) classes A, B, and C (mild, moderate, and severe, respectively) cirrhosis were supplemented with a placebo or supranutritional amounts of selenium as selenate (200 or 400 μg/d) or as selenomethionine (200 μg/d) for 4 wk. Plasma SEPP1 concentration and glutathione peroxidase (GPX) activity, the latter due largely to the selenoprotein GPX3 secreted by the kidneys, were measured before and after supplementation. RESULTS GPX activity was increased more by both doses of selenate than by the placebo in C-P class B patients. The activity was not increased more by selenomethionine supplementation than by the placebo in C-P class B patients. Plasma selenium was increased more by 400 μg Se as selenate than by the placebo in C-P class C patients. Within the groups who responded to selenate, there was a considerable variation in responses. CONCLUSION These results indicate that severe cirrhosis causes mild functional selenium deficiency in some patients that is associated with impaired metabolism of selenomethionine. This trial was registered at clinicaltrials.gov as NCT00271245.
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Affiliation(s)
- Raymond F Burk
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, and
| | - Kristina E Hill
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, and
| | - Amy K Motley
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, and
| | - Daniel W Byrne
- Department of Biostatistics, Vanderbilt University School of Medicine, Nashville, TN
| | - Brooke K Norsworthy
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, and
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Barrett CW, Reddy VK, Short SP, Motley AK, Lintel MK, Bradley AM, Freeman T, Vallance J, Ning W, Parang B, Poindexter SV, Fingleton B, Chen X, Washington MK, Wilson KT, Shroyer NF, Hill KE, Burk RF, Williams CS. Selenoprotein P influences colitis-induced tumorigenesis by mediating stemness and oxidative damage. J Clin Invest 2015; 125:2646-60. [PMID: 26053663 DOI: 10.1172/jci76099] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 04/30/2015] [Indexed: 12/19/2022] Open
Abstract
Patients with inflammatory bowel disease are at increased risk for colon cancer due to augmented oxidative stress. These patients also have compromised antioxidant defenses as the result of nutritional deficiencies. The micronutrient selenium is essential for selenoprotein production and is transported from the liver to target tissues via selenoprotein P (SEPP1). Target tissues also produce SEPP1, which is thought to possess an endogenous antioxidant function. Here, we have shown that mice with Sepp1 haploinsufficiency or mutations that disrupt either the selenium transport or the enzymatic domain of SEPP1 exhibit increased colitis-associated carcinogenesis as the result of increased genomic instability and promotion of a protumorigenic microenvironment. Reduced SEPP1 function markedly increased M2-polarized macrophages, indicating a role for SEPP1 in macrophage polarization and immune function. Furthermore, compared with partial loss, complete loss of SEPP1 substantially reduced tumor burden, in part due to increased apoptosis. Using intestinal organoid cultures, we found that, compared with those from WT animals, Sepp1-null cultures display increased stem cell characteristics that are coupled with increased ROS production, DNA damage, proliferation, decreased cell survival, and modulation of WNT signaling in response to H2O2-mediated oxidative stress. Together, these data demonstrate that SEPP1 influences inflammatory tumorigenesis by affecting genomic stability, the inflammatory microenvironment, and epithelial stem cell functions.
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Abstract
Selenium is transferred from the mouse dam to its neonate via milk. Milk contains selenium in selenoprotein form as selenoprotein P (Sepp1) and glutathione peroxidase-3 (Gpx3) as well as in non-specific protein form as selenomethionine. Selenium is also present in milk in uncharacterized small-molecule form. We eliminated selenomethionine from the mice in these experiments by feeding a diet that contained sodium selenite as the source of selenium. Selenium-replete dams with deletion of Sepp1 or Gpx3 were studied to assess the effects of these genes on selenium transfer to the neonate. Sepp1 knockout caused a drop in milk selenium to 27% of the value in wild-type milk and a drop in selenium acquisition by the neonates to 35%. In addition to decreasing milk selenium by eliminating Sepp1, deletion of Sepp1 causes a decline in whole-body selenium, which likely also contributes to the decreased transfer of selenium to the neonate. Deletion of Gpx3 did not decrease milk selenium content or neonate selenium acquisition by measurable amounts. Thus, when the dam is fed selenium-adequate diet (0.25 mg selenium/kg diet), milk Sepp1 transfers a large amount of selenium to neonates but the transfer of selenium by Gpx3 is below detection by our methods.
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Affiliation(s)
- Kristina E. Hill
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- * E-mail:
| | - Amy K. Motley
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Virginia P. Winfrey
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Raymond F. Burk
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
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Burk RF, Hill KE, Motley AK, Winfrey VP, Kurokawa S, Mitchell SL, Zhang W. Selenoprotein P and apolipoprotein E receptor-2 interact at the blood-brain barrier and also within the brain to maintain an essential selenium pool that protects against neurodegeneration. FASEB J 2014; 28:3579-88. [PMID: 24760755 DOI: 10.1096/fj.14-252874] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Selenoprotein P (Sepp1) and its receptor, apolipoprotein E receptor 2 (apoER2), account for brain retaining selenium better than other tissues. The primary sources of Sepp1 in plasma and brain are hepatocytes and astrocytes, respectively. ApoER2 is expressed in varying amounts by tissues; within the brain it is expressed primarily by neurons. Knockout of Sepp1 or apoER2 lowers brain selenium from ∼120 to ∼50 ng/g and leads to severe neurodegeneration and death in mild selenium deficiency. Interactions of Sepp1 and apoER2 that protect against this injury have not been characterized. We studied Sepp1, apoER2, and brain selenium in knockout mice. Immunocytochemistry showed that apoER2 mediates Sepp1 uptake at the blood-brain barrier. When Sepp1(-/-) or apoER2(-/-) mice developed severe neurodegeneration caused by mild selenium deficiency, brain selenium was ∼35 ng/g. In extreme selenium deficiency, however, brain selenium of ∼12 ng/g was tolerated when both Sepp1 and apoER2 were intact in the brain. These findings indicate that tandem Sepp1-apoER2 interactions supply selenium for maintenance of brain neurons. One interaction is at the blood-brain barrier, and the other is within the brain. We postulate that Sepp1 inside the blood-brain barrier is taken up by neurons via apoER2, concentrating brain selenium in them.
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Affiliation(s)
- Raymond F Burk
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Kristina E Hill
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Amy K Motley
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Virginia P Winfrey
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Suguru Kurokawa
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Stuart L Mitchell
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Wanqi Zhang
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
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Kurokawa S, Eriksson S, Rose KL, Wu S, Motley AK, Hill S, Winfrey VP, McDonald WH, Capecchi MR, Atkins JF, Arnér ESJ, Hill KE, Burk RF. Sepp1(UF) forms are N-terminal selenoprotein P truncations that have peroxidase activity when coupled with thioredoxin reductase-1. Free Radic Biol Med 2014; 69:67-76. [PMID: 24434121 PMCID: PMC3960317 DOI: 10.1016/j.freeradbiomed.2014.01.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 01/06/2014] [Accepted: 01/07/2014] [Indexed: 01/18/2023]
Abstract
Mouse selenoprotein P (Sepp1) consists of an N-terminal domain (residues 1-239) that contains one selenocysteine (U) as residue 40 in a proposed redox-active motif (-UYLC-) and a C-terminal domain (residues 240-361) that contains nine selenocysteines. Sepp1 transports selenium from the liver to other tissues by receptor-mediated endocytosis. It also reduces oxidative stress in vivo by an unknown mechanism. A previously uncharacterized plasma form of Sepp1 is filtered in the glomerulus and taken up by renal proximal convoluted tubule (PCT) cells via megalin-mediated endocytosis. We purified Sepp1 forms from the urine of megalin(-/-) mice using a monoclonal antibody to the N-terminal domain. Mass spectrometry revealed that the purified urinary Sepp1 consisted of N-terminal fragments terminating at 11 sites between residues 183 and 208. They were therefore designated Sepp1(UF). Because the N-terminal domain of Sepp1 has a thioredoxin fold, Sepp1(UF) were compared with full-length Sepp1, Sepp1(Δ240-361), and Sepp1(U40S) as a substrate of thioredoxin reductase-1 (TrxR1). All forms of Sepp1 except Sepp1(U40S), which contains serine in place of the selenocysteine, were TrxR1 substrates, catalyzing NADPH oxidation when coupled with H2O2 or tert-butylhydroperoxide as the terminal electron acceptor. These results are compatible with proteolytic cleavage freeing Sepp1(UF) from full-length Sepp1, the form that has the role of selenium transport, allowing Sepp1(UF) to function by itself as a peroxidase. Ultimately, plasma Sepp1(UF) and small selenium-containing proteins are filtered by the glomerulus and taken up by PCT cells via megalin-mediated endocytosis, preventing loss of selenium in the urine and providing selenium for the synthesis of glutathione peroxidase-3.
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Affiliation(s)
- Suguru Kurokawa
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Sofi Eriksson
- Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Kristie L Rose
- Vanderbilt Proteomics Laboratory in the Mass Spectrometry Research Center, Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Sen Wu
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA
| | - Amy K Motley
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Salisha Hill
- Vanderbilt Proteomics Laboratory in the Mass Spectrometry Research Center, Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Virginia P Winfrey
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - W Hayes McDonald
- Vanderbilt Proteomics Laboratory in the Mass Spectrometry Research Center, Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Mario R Capecchi
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA
| | - John F Atkins
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA; Department of Biochemistry, University College Cork, Cork, Ireland
| | - Elias S J Arnér
- Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Kristina E Hill
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Raymond F Burk
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
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9
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Barrett CW, Singh K, Motley AK, Lintel MK, Matafonova E, Bradley AM, Ning W, Poindexter SV, Parang B, Reddy VK, Chaturvedi R, Fingleton BM, Washington MK, Wilson KT, Davies SS, Hill KE, Burk RF, Williams CS. Dietary selenium deficiency exacerbates DSS-induced epithelial injury and AOM/DSS-induced tumorigenesis. PLoS One 2013; 8:e67845. [PMID: 23861820 PMCID: PMC3701622 DOI: 10.1371/journal.pone.0067845] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 05/21/2013] [Indexed: 12/13/2022] Open
Abstract
Selenium (Se) is an essential micronutrient that exerts its functions via selenoproteins. Little is known about the role of Se in inflammatory bowel disease (IBD). Epidemiological studies have inversely correlated nutritional Se status with IBD severity and colon cancer risk. Moreover, molecular studies have revealed that Se deficiency activates WNT signaling, a pathway essential to intestinal stem cell programs and pivotal to injury recovery processes in IBD that is also activated in inflammatory neoplastic transformation. In order to better understand the role of Se in epithelial injury and tumorigenesis resulting from inflammatory stimuli, we examined colonic phenotypes in Se-deficient or -sufficient mice in response to dextran sodium sulfate (DSS)-induced colitis, and azoxymethane (AOM) followed by cyclical administration of DSS, respectively. In response to DSS alone, Se-deficient mice demonstrated increased morbidity, weight loss, stool scores, and colonic injury with a concomitant increase in DNA damage and increases in inflammation-related cytokines. As there was an increase in DNA damage as well as expression of several EGF and TGF-β pathway genes in response to inflammatory injury, we sought to determine if tumorigenesis was altered in the setting of inflammatory carcinogenesis. Se-deficient mice subjected to AOM/DSS treatment to model colitis-associated cancer (CAC) had increased tumor number, though not size, as well as increased incidence of high grade dysplasia. This increase in tumor initiation was likely due to a general increase in colonic DNA damage, as increased 8-OHdG staining was seen in Se-deficient tumors and adjacent, non-tumor mucosa. Taken together, our results indicate that Se deficiency worsens experimental colitis and promotes tumor development and progression in inflammatory carcinogenesis.
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Affiliation(s)
- Caitlyn W. Barrett
- Department of Medicine, Division of Gastroenterology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Department of Cancer Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Kshipra Singh
- Department of Medicine, Division of Gastroenterology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Veterans Affairs Tennessee Valley Health Care System, Nashville, Tennessee, United States of America
| | - Amy K. Motley
- Department of Medicine, Division of Gastroenterology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Mary K. Lintel
- Department of Medicine, Division of Gastroenterology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Elena Matafonova
- Division of Clinical Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Amber M. Bradley
- Department of Medicine, Division of Gastroenterology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Wei Ning
- Department of Medicine, Division of Gastroenterology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Shenika V. Poindexter
- Department of Medicine, Division of Gastroenterology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Department of Cancer Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Bobak Parang
- Department of Medicine, Division of Gastroenterology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Department of Cancer Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Vishruth K. Reddy
- Department of Medicine, Division of Gastroenterology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Rupesh Chaturvedi
- Department of Medicine, Division of Gastroenterology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Veterans Affairs Tennessee Valley Health Care System, Nashville, Tennessee, United States of America
| | - Barbara M. Fingleton
- Department of Cancer Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Mary K. Washington
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Keith T. Wilson
- Department of Medicine, Division of Gastroenterology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Department of Cancer Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Vanderbilt Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Veterans Affairs Tennessee Valley Health Care System, Nashville, Tennessee, United States of America
| | - Sean S. Davies
- Division of Clinical Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Kristina E. Hill
- Department of Medicine, Division of Gastroenterology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Raymond F. Burk
- Department of Medicine, Division of Gastroenterology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Christopher S. Williams
- Department of Medicine, Division of Gastroenterology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Department of Cancer Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Vanderbilt Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Veterans Affairs Tennessee Valley Health Care System, Nashville, Tennessee, United States of America
- * E-mail:
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Abstract
Selenoprotein P (Sepp1) is taken up by receptor-mediated endocytosis for its selenium. The other extracellular selenoprotein, glutathione peroxidase-3 (Gpx3), has not been shown to transport selenium. Mice with genetic alterations of Sepp1, the Sepp1 receptors apolipoprotein E receptor-2 (apoER2) and megalin, and Gpx3 were used to investigate maternal-fetal selenium transfer. Immunocytochemistry (ICC) showed receptor-independent uptake of Sepp1 and Gpx3 in the same vesicles of d-13 visceral yolk sac cells, suggesting uptake by pinocytosis. ICC also showed apoER2-mediated uptake of maternal Sepp1 in the d-18 placenta. Thus, two selenoprotein-dependent maternal-fetal selenium transfer mechanisms were identified. Selenium was quantified in d-18 fetuses with the mechanisms disrupted. Maternal Sepp1 deletion, which lowers maternal whole-body selenium, decreased fetal selenium under selenium-adequate conditions but deletion of fetal apoER2 did not. Fetal apoER2 deletion did decrease fetal selenium, by 51%, under selenium-deficient conditions, verifying function of the placental Sepp1-apoER2 mechanism. Maternal Gpx3 deletion decreased fetal selenium, by 13%, but only under selenium-deficient conditions. These findings indicate that the selenoprotein uptake mechanisms ensure selenium transfer to the fetus under selenium-deficient conditions. The failure of their disruptions (apoER2 deletion, Gpx3 deletion) to affect fetal selenium under selenium-adequate conditions indicates the existence of an additional maternal-fetal selenium transfer mechanism.
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Affiliation(s)
- Raymond F Burk
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
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11
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Abstract
Whole-body selenium is regulated by excretion of the element. Reports of studies carried out using isotopic tracers have led to the conclusion that urinary selenium excretion is regulated by selenium intake but that fecal excretion is not. Because of the limitations of tracer studies, we measured urinary and fecal selenium excretion by mice with selenium intakes in the form of sodium selenite ranging from deficient to almost toxic. Tissue and whole-body selenium concentrations increased sharply between deficient and adequate selenium intakes, reflecting tissue accumulation of selenium in the form of selenoproteins. Once the requirement for selenium had been satisfied, a 31-fold further increase in intake resulted in less than doubling of tissue and whole-body selenium, demonstrating the effectiveness of selenium excretion by the mouse. Urinary selenium excretion increased with increases in dietary selenium intake. Fecal selenium excretion, which was 20 to 30 % of the selenium excreted in the physiological range, responded to moderately high selenium intake but did not increase further when selenium intake was increased to even higher levels. Thus, fecal selenium excretion contributes to regulation of whole-body selenium at physiological selenium intakes. The pattern of its response to the full spectrum of selenium intakes was different from the urinary excretion response, suggesting that the mechanisms of fecal and urinary routes of excretion are different.
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Affiliation(s)
- Lucia F C Pedrosa
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN, USA.
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Hill KE, Wu S, Motley AK, Stevenson TD, Winfrey VP, Capecchi MR, Atkins JF, Burk RF. Production of selenoprotein P (Sepp1) by hepatocytes is central to selenium homeostasis. J Biol Chem 2012; 287:40414-24. [PMID: 23038251 DOI: 10.1074/jbc.m112.421404] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Sepp1 transports selenium, but its complete role in selenium homeostasis is not known. RESULTS Deletion of Sepp1 in hepatocytes increases liver selenium at the expense of other tissues and decreases whole-body selenium by increasing excretion. CONCLUSION Sepp1 production by hepatocytes retains selenium in the organism and distributes it from the liver to peripheral tissues. SIGNIFICANCE Sepp1 is central to selenium homeostasis. Sepp1 is a widely expressed extracellular protein that in humans and mice contains 10 selenocysteine residues in its primary structure. Extra-hepatic tissues take up plasma Sepp1 for its selenium via apolipoprotein E receptor-2 (apoER2)-mediated endocytosis. The role of Sepp1 in the transport of selenium from liver, a rich source of the element, to peripheral tissues was studied using mice with selective deletion of Sepp1 in hepatocytes (Sepp1(c/c)/alb-cre(+/-) mice). Deletion of Sepp1 in hepatocytes lowered plasma Sepp1 concentration to 10% of that in Sepp1(c/c) mice (controls) and increased urinary selenium excretion, decreasing whole-body and tissue selenium concentrations. Under selenium-deficient conditions, Sepp1(c/c)/alb-cre(+/-) mice accumulated selenium in the liver at the expense of extra-hepatic tissues, severely worsening clinical manifestations of dietary selenium deficiency. These findings are consistent with there being competition for metabolically available hepatocyte selenium between the synthesis of selenoproteins and the synthesis of selenium excretory metabolites. In addition, selenium deficiency down-regulated the mRNA of the most abundant hepatic selenoprotein, glutathione peroxidase-1 (Gpx1), to 15% of the selenium-replete value, while reducing Sepp1 mRNA, the most abundant hepatic selenoprotein mRNA, only to 61%. This strongly suggests that Sepp1 synthesis is favored in the liver over Gpx1 synthesis when selenium supply is limited, directing hepatocyte selenium to peripheral tissues in selenium deficiency. We conclude that production of Sepp1 by hepatocytes is central to selenium homeostasis in the organism because it promotes retention of selenium in the body and effects selenium distribution from the liver to extra-hepatic tissues, especially under selenium-deficient conditions.
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Affiliation(s)
- Kristina E Hill
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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13
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Hill KE, Motley AK, Atkins JF, Capecchi MR, Wu S, Burk RF. Selenoprotein P (Sepp1) Synthesis by the Liver Protects against Selenium Deficiency. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.241.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Amy K. Motley
- GI/MedicineVanderbilt University Medical CenterNashvilleTN
| | | | | | - Sen Wu
- Human GeneticsUniversity of UtahSalt Lake CityUT
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Xia Y, Hill KE, Li P, Xu J, Zhou D, Motley AK, Wang L, Byrne DW, Burk RF. Optimization of selenoprotein P and other plasma selenium biomarkers for the assessment of the selenium nutritional requirement: a placebo-controlled, double-blind study of selenomethionine supplementation in selenium-deficient Chinese subjects. Am J Clin Nutr 2010; 92:525-31. [PMID: 20573787 PMCID: PMC2921536 DOI: 10.3945/ajcn.2010.29642] [Citation(s) in RCA: 155] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The intake of selenium needed for optimal health has not been established. Selenoproteins perform the functions of selenium, and the selenium intake needed for their full expression is not known. OBJECTIVE This study sought to determine the intake of selenium required to optimize plasma selenoprotein P (SEPP1) and to compare SEPP1 with other plasma selenium biomarkers. DESIGN A 40-wk placebo-controlled, double-blind study of selenium repletion was carried out in 98 healthy Chinese subjects who had a daily dietary selenium intake of 14 micro g. Fourteen subjects each were assigned randomly to daily dose groups of 0, 21, 35, 55, 79, 102, and 125 micro g Se as l-selenomethionine. Plasma glutathione peroxidase (GPX) activity, SEPP1, and selenium were measured. A biomarker was considered to be optimized when its value was not different from the mean value of the subjects receiving larger supplements. RESULTS The SEPP1 concentration was optimized at 40 wk by the 35- micro g supplement, which indicated that 49 micro g/d could optimize it. GPX activity was optimized by 21 micro g (total ingestion: 35 micro g/d). The selenium concentration showed no tendency to become optimized. CONCLUSIONS The present results indicate that SEPP1 concentration is the best plasma biomarker studied for assessing optimal expression of all selenoproteins, because its optimization required a larger intake of selenium than did GPX activity. On the basis of the selenium intake needed for SEPP1 optimization with adjustments for body weight and individual variation, ap 75 micro g Se/d as selenomethionine is postulated to allow full expression of selenoproteins in US residents. This trial was registered at clinicaltrials.gov as NCT00428649.
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Affiliation(s)
- Yiming Xia
- Sichuan Provincial Center for Disease Control and Prevention, Chengdu, China
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15
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Hurst R, Armah CN, Dainty JR, Hart DJ, Teucher B, Goldson AJ, Broadley MR, Motley AK, Fairweather-Tait SJ. Establishing optimal selenium status: results of a randomized, double-blind, placebo-controlled trial. Am J Clin Nutr 2010; 91:923-31. [PMID: 20181815 PMCID: PMC2844680 DOI: 10.3945/ajcn.2009.28169] [Citation(s) in RCA: 191] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Dietary recommendations for selenium differ between countries, mainly because of uncertainties over the definition of optimal selenium status. OBJECTIVE The objective was to examine the dose-response relations for different forms of selenium. DESIGN A randomized, double-blind, placebo-controlled dietary intervention was carried out in 119 healthy men and women aged 50-64 y living in the United Kingdom. Daily placebo or selenium-enriched yeast tablets containing 50, 100, or 200 microg Se ( approximately 60% selenomethionine), selenium-enriched onion meals ( approximately 66% gamma-glutamyl-methylselenocysteine, providing the equivalent of 50 microg Se/d), or unenriched onion meals were consumed for 12 wk. Changes in platelet glutathione peroxidase activity and in plasma selenium and selenoprotein P concentrations were measured. RESULTS The mean baseline plasma selenium concentration for all subjects was 95.7 +/- 11.5 ng/mL, which increased significantly by 10 wk to steady state concentrations of 118.3 +/- 13.1, 152.0 +/- 24.3, and 177.4 +/- 26.3 ng/mL in those who consumed 50, 100, or 200 microg Se-yeast/d, respectively. Platelet glutathione peroxidase activity did not change significantly in response to either dose or form of selenium. Selenoprotein P increased significantly in all selenium intervention groups from an overall baseline mean of 4.99 +/- 0.80 microg/mL to 6.17 +/- 0.85, 6.73 +/- 1.01, 6.59 +/- 0.64, and 5.72 +/- 0.75 microg/mL in those who consumed 50, 100, or 200 microg Se-yeast/d and 50 microg Se-enriched onions/d, respectively. CONCLUSIONS Plasma selenoprotein P is a useful biomarker of status in populations with relatively low selenium intakes because it responds to different dietary forms of selenium. To optimize the plasma selenoprotein P concentration in this study, 50 microg Se/d was required in addition to the habitual intake of approximately 55 microg/d. In the context of established relations between plasma selenium and risk of cancer and mortality, and recognizing the important functions of selenoprotein P, these results provide important evidence for deriving estimated average requirements for selenium in adults. This trial was registered at clinicaltrials.gov as NCT00279812.
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Affiliation(s)
- Rachel Hurst
- School of Medicine, Health Policy and Practice, University of East Anglia, Norwich, UK.
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16
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Olson GE, Whitin JC, Hill KE, Winfrey VP, Motley AK, Austin LM, Deal J, Cohen HJ, Burk RF. Extracellular glutathione peroxidase (Gpx3) binds specifically to basement membranes of mouse renal cortex tubule cells. Am J Physiol Renal Physiol 2009; 298:F1244-53. [PMID: 20015939 DOI: 10.1152/ajprenal.00662.2009] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Glutathione peroxidase-3 (Gpx3), also known as plasma or extracellular glutathione peroxidase, is a selenoprotein secreted primarily by kidney proximal convoluted tubule cells. In this study Gpx3(-/-) mice have been produced and immunocytochemical techniques have been developed to investigate Gpx3 metabolism. Gpx3(-/-) mice maintained the same whole-body content and urinary excretion of selenium as did Gpx3(+/+) mice. They tolerated selenium deficiency without observable ill effects. The simultaneous knockout of Gpx3 and selenoprotein P revealed that these two selenoproteins account for >97% of plasma selenium. Immunocytochemistry experiments demonstrated that Gpx3 binds selectively, both in vivo and in vitro, to basement membranes of renal cortical proximal and distal convoluted tubules. Based on calculations using selenium content, the kidney pool of Gpx3 is over twice as large as the plasma pool. These data indicate that Gpx3 does not serve in the regulation of selenium metabolism. The specific binding of a large pool of Gpx3 to basement membranes in the kidney cortex strongly suggests a need for glutathione peroxidase activity in the cortical peritubular space.
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Affiliation(s)
- Gary E Olson
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
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17
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Burk RF, Xia Y, Hill KE, Motley AK. Selenium biomarkers in Chinese subjects supplemented with selenium. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.346.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Yiming Xia
- Institute of Nutrition and Food Safety, China, CDCBeijingPeople's Republic of China
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18
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Camargo MC, Burk RF, Bravo LE, Piazuelo MB, Hill KE, Fontham ET, Motley AK, Yepez MC, Mora Y, Schneider BG, Correa P. Plasma selenium measurements in subjects from areas with contrasting gastric cancer risks in Colombia. Arch Med Res 2008; 39:443-51. [PMID: 18375257 PMCID: PMC2394852 DOI: 10.1016/j.arcmed.2007.12.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2007] [Accepted: 12/10/2007] [Indexed: 01/08/2023]
Abstract
BACKGROUND An inverse association between selenium status and incidence of different neoplasias including gastric cancer has been reported. This pilot study aimed to determine and compare selenium status in two Colombian populations with different gastric cancer risks: a high-risk area in the volcanic region of the Andes Mountains and a low-risk area on the Pacific coast. METHODS Eighty nine adult males were recruited in the outpatient clinics of two public hospitals (44 and 45 from high- and low-risk areas, respectively) and provided a blood sample. Seventy one (79.8%) participants underwent upper gastrointestinal endoscopy. Plasma selenium was assayed using a fluorometric method, selenoprotein-P by ELISA, and glutathione peroxidase activity by a spectrophometric method. Histological diagnosis and Helicobacter pylori infection were evaluated in gastric biopsy samples. Unpaired samples t-test and linear regression analyses were used for statistical analyses. RESULTS Although none of the subjects in either of the two geographic areas was selenium deficient, the level of plasma selenium was significantly lower in men from the high-risk area compared with those from the low-risk area. Levels of selenoprotein-P and glutathione peroxidase activity were similar between groups after adjustment for confounders. Selenium measurements were not associated with histopathological diagnosis. CONCLUSIONS The high incidence of gastric cancer in the Andean region of Colombia is unlikely to be explained by selenium deficiency. We cannot exclude, however, that suboptimal selenium levels may exist in the gastric mucosa of subjects in the high-risk area. Therefore, the benefit of selenium supplementation in gastric cancer prevention cannot be dismissed.
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Affiliation(s)
- Maria Constanza Camargo
- Department of Medicine, School of Medicine, Division of Gastroenterology, Hepatology and Nutrition, Vanderbilt University, Nashville, Tennessee
| | - Raymond F. Burk
- Department of Pathology, School of Medicine, Universidad del Valle, Cali, Colombia
| | - Luis E. Bravo
- Department of Pathology, School of Medicine, Universidad del Valle, Cali, Colombia
| | - Maria B. Piazuelo
- Department of Medicine, School of Medicine, Division of Gastroenterology, Hepatology and Nutrition, Vanderbilt University, Nashville, Tennessee
| | - Kristina E. Hill
- Department of Medicine, School of Medicine, Division of Gastroenterology, Hepatology and Nutrition, Vanderbilt University, Nashville, Tennessee
| | - Elizabeth T. Fontham
- School of Public Health, Louisiana State University Health Sciences Center, New Orleans, Louisiana
| | - Amy K. Motley
- Department of Medicine, School of Medicine, Division of Gastroenterology, Hepatology and Nutrition, Vanderbilt University, Nashville, Tennessee
| | - Maria C. Yepez
- Centro de Estudios en Salud, Universidad de Nariño, Pasto, Colombia
| | - Yolanda Mora
- Centro de Estudios en Salud, Universidad de Nariño, Pasto, Colombia
| | - Barbara G. Schneider
- Department of Medicine, School of Medicine, Division of Gastroenterology, Hepatology and Nutrition, Vanderbilt University, Nashville, Tennessee
| | - Pelayo Correa
- Department of Medicine, School of Medicine, Division of Gastroenterology, Hepatology and Nutrition, Vanderbilt University, Nashville, Tennessee
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19
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Burk RF, Hill KE, Nakayama A, Mostert V, Levander XA, Motley AK, Johnson DA, Johnson JA, Freeman ML, Austin LM. Selenium deficiency activates mouse liver Nrf2-ARE but vitamin E deficiency does not. Free Radic Biol Med 2008; 44:1617-23. [PMID: 18279678 PMCID: PMC2346531 DOI: 10.1016/j.freeradbiomed.2008.01.016] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Revised: 01/10/2008] [Accepted: 01/15/2008] [Indexed: 11/24/2022]
Abstract
Selenium (Se) and vitamin E are antioxidant micronutrients. Se functions through selenoproteins and vitamin E reacts with oxidizing molecules in membranes. The relationship of these micronutrients with the Nrf2-antioxidant response element (ARE) pathway was investigated using ARE-reporter mice and Nrf2-/- mice. Weanling males were fed Se-deficient (0 Se), vitamin E-deficient (0 E), or control diet for 16 or 22 weeks. The ARE reporter was elevated 450-fold in 0 Se liver but was not elevated in 0 E liver. Antioxidant enzymes induced by Nrf2-ARE (glutathione S-transferase (GST), NAD(P)H quinone oxidoreductase (NQOR), and heme oxygenase-1 (HO-1)) were elevated in 0 Se livers but not in 0 E livers. Deletion of Nrf2 had varying effects on the inductions, with GST induction being abolished by it but induction of NQOR and HO-1 still occurring. Thus, Se deficiency, but not vitamin E deficiency, induces a number of enzymes that protect against oxidative stress and modify xenobiotic metabolism through Nrf2-ARE and other stress-response pathways. We conclude that Se deficiency causes cytosolic oxidative stress but that vitamin E deficiency does not. This suggests that the oxidant defense mechanisms in which these antioxidant nutrients function are independent of one another.
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Affiliation(s)
- Raymond F Burk
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232-0252, USA.
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20
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Burk RF, Hill KE, Nakayama A, Mostert V, Levander XA, Motley AK, Freeman ML, Austin LM. Selenium Deficiency, but Not Vitamin E Deficiency, Activates the Mouse Liver Nrf2‐ARE Pathway. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.156.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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21
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Burk RF, Hill KE, Olson GE, Weeber EJ, Motley AK, Winfrey VP, Austin LM. Deletion of apolipoprotein E receptor-2 in mice lowers brain selenium and causes severe neurological dysfunction and death when a low-selenium diet is fed. J Neurosci 2007; 27:6207-11. [PMID: 17553992 PMCID: PMC6672153 DOI: 10.1523/jneurosci.1153-07.2007] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Selenoprotein P (Sepp1) is a plasma and extracellular protein that is rich in selenium. Deletion of Sepp1 results in sharp decreases of selenium levels in the brain and testis with dysfunction of those organs. Deletion of Sepp1 also causes increased urinary selenium excretion, leading to moderate depletion of whole-body selenium. The lipoprotein receptor apolipoprotein E receptor-2 (apoER2) binds Sepp1 and facilitates its uptake by Sertoli cells, thus providing selenium for spermatogenesis. Experiments were performed to assess the effect of apoER2 on the concentration and function of selenium in the brain and on whole-body selenium. ApoER2-/- and apoER2+/+ male mice were fed a semipurified diet with selenite added as the source of selenium. ApoER2-/- mice had depressed brain and testis selenium, but normal levels in liver, kidney, muscle, and the whole body. Feeding a selenium-deficient diet to apoER2-/- mice led to neurological dysfunction and death, with some of the characteristics exhibited by Sepp1-/- mice fed the same diet. Thus, although it does not affect whole-body selenium, apoER2 is necessary for maintenance of brain selenium and for prevention of neurological dysfunction and death under conditions of selenium deficiency, suggesting an interaction of apoER2 with Sepp1 in the brain.
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Affiliation(s)
- Raymond F Burk
- Division of Gastroenterology, Hepatology, and Nutrition, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA.
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22
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Hill KE, Zhou J, Austin LM, Motley AK, Ham AJL, Olson GE, Atkins JF, Gesteland RF, Burk RF. The Selenium-rich C-terminal Domain of Mouse Selenoprotein P Is Necessary for the Supply of Selenium to Brain and Testis but Not for the Maintenance of Whole Body Selenium. J Biol Chem 2007; 282:10972-80. [PMID: 17311913 DOI: 10.1074/jbc.m700436200] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Selenoprotein P (Sepp1) has two domains with respect to selenium content: the N-terminal, selenium-poor domain and the C-terminal, selenium-rich domain. To assess domain function, mice with deletion of the C-terminal domain have been produced and compared with Sepp1-/- and Sepp1+/+ mice. All mice studied were males fed a semipurified diet with defined selenium content. The Sepp1 protein in the plasma of mice with the C-terminal domain deleted was determined by mass spectrometry to terminate after serine 239 and thus was designated Sepp1Delta240-361. Plasma Sepp1 and selenium concentrations as well as glutathione peroxidase activity were determined in the three types of mice. Glutathione peroxidase and Sepp1Delta240-361 accounted for over 90% of the selenium in the plasma of Sepp1Delta240-361 mice. Calculations using results from Sepp1+/+ mice revealed that Sepp1, with a potential for containing 10 selenocysteine residues, contained an average of 5 selenium atoms per molecule, indicating that shortened and/or selenium-depleted forms of the protein were present in these wild-type mice. Sepp1Delta240-361 mice had low brain and testis selenium concentrations that were similar to those in Sepp1-/- mice but they better maintained their whole body selenium. Sepp1Delta240-361 mice had depressed fertility, even when they were fed a high selenium diet, and their spermatozoa were defective and morphologically indistinguishable from those of selenium-deficient mice. Neurological dysfunction and death occurred when Sepp1Delta240-361 mice were fed selenium-deficient diet. These phenotypes were similar to those of Sepp1-/- mice but had later onset or were less severe. The results of this study demonstrate that the C terminus of Sepp1 is critical for the maintenance of selenium in brain and testis but not for the maintenance of whole body selenium.
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Affiliation(s)
- Kristina E Hill
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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Abstract
The brain and testis retain selenium better than other tissues during selenium deficiency. Studies of mice with selenoprotein P (Sepp1) deleted (Sepp1(-/-) mice) showed that brain and testis selenium levels are largely dependent on Sepp1. Therefore, we examined tissue selenium in mice fed varying amounts of selenium and in Sepp1(-/-) mice to characterize better the role(s) of Sepp1. Mice were fed a selenium-deficient diet for 8 wk supplemented with selenium as selenite from none to 0.25 mg/kg diet and tissue selenium was measured. Brain and testis maintained their selenium better than did liver, kidney, and muscle when dietary selenium was limiting but testis selenium fell sharply in the group fed the deficient diet. Brain retained its selenium well, even in the group fed the deficient diet. After intravenous injection of (75)Se-Sepp1 into Sepp1(-/-) and Sepp1(+/+) mice, qualitative differences between brain and testis (75)Se uptake were noted, further suggesting differences in their uptake of selenium from Sepp1. Finally, selenium was measured in brain regions of Sepp1(-/-) and Sepp1(+/+) mice fed the diet supplemented with 1 mg selenium/kg and Sepp1(+/+) mice fed the deficient diet. Deletion of Sepp1 and selenium deficiency each lowered selenium a similar amount in cortex, midbrain, brainstem, and cerebellum. Selenium in the hippocampus was lowered by deletion of Sepp1 but not by selenium deficiency. These results suggest that Sepp1 is more important for maintaining selenium in the hippocampus than in other brain regions. They also confirm the position of the brain at the apex of the organ selenium hierarchy.
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Affiliation(s)
- Akihiro Nakayama
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232-0252, USA
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Burk RF, Norsworthy BK, Hill KE, Motley AK, Byrne DW. Effects of chemical form of selenium on plasma biomarkers in a high-dose human supplementation trial. Cancer Epidemiol Biomarkers Prev 2006; 15:804-10. [PMID: 16614127 DOI: 10.1158/1055-9965.epi-05-0950] [Citation(s) in RCA: 200] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Intervention trials with different forms of selenium are under way to assess the effects of selenium supplements on the incidence of cancer and other diseases. Plasma selenium biomarkers respond to selenium administration and might be useful for assessing compliance and safety in these trials. The present study characterized the effects of selenium supplementation on plasma selenium biomarkers and urinary selenium excretion in selenium-replete subjects. Moderate (approximately 200 microg/d) to large (approximately 600 microg/d) selenium supplements in the forms sodium selenite, high-selenium yeast (yeast), and l-selenomethionine (selenomethionine) were administered. Subjects were randomized into 10 groups (placebo and three dose levels of each form of selenium). Plasma biomarkers (selenium concentration, selenoprotein P concentration, and glutathione peroxidase activity) were determined before supplementation and every 4 weeks for 16 weeks. Urinary selenium excretion was determined at 16 weeks. Supplementation with selenomethionine and yeast raised the plasma selenium concentration in a dose-dependent manner. Selenite did not. The increased selenium concentration correlated with the amount of selenomethionine administered. Neither glutathione peroxidase activity nor selenoprotein P concentration responded to selenium supplementation. Urinary selenium excretion was greater after selenomethionine than after selenite, with excretion after yeast being intermediate and not significantly different from either of the other two. We conclude that plasma selenium concentration is useful in monitoring compliance and safety of selenium supplementation as selenomethionine but not as selenite. Plasma selenium seems to reflect the selenomethionine content of yeast but not the other yeast selenium forms. As judged by urinary selenium excretion, selenium in the form of selenomethionine is better absorbed than selenite.
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Affiliation(s)
- Raymond F Burk
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232-0252, USA.
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Burk RF, Hill KE, Motley AK, Austin LM, Norsworthy BK. Deletion of selenoprotein P upregulates urinary selenium excretion and depresses whole-body selenium content. Biochim Biophys Acta Gen Subj 2006; 1760:1789-93. [PMID: 17014962 PMCID: PMC1761947 DOI: 10.1016/j.bbagen.2006.08.010] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2006] [Revised: 08/10/2006] [Accepted: 08/15/2006] [Indexed: 11/25/2022]
Abstract
Deletion of the mouse selenoprotein P gene (Sepp1) lowers selenium concentrations in many tissues. We examined selenium homeostasis in Sepp1(-/-) and Sepp1(+/+) mice to assess the mechanism of this. The liver produces and exports selenoprotein P, which transports selenium to peripheral tissues, and urinary selenium metabolites, which regulate whole-body selenium. At intakes of selenium near the nutritional requirement, Sepp1(-/-) mice had whole-body selenium concentrations 72 to 75% of Sepp1(+/+) mice. Genotype did not affect dietary intake of selenium. Sepp1(-/-) mice excreted in their urine approximately 1.5 times more selenium in relation to their whole-body selenium than did Sepp1(+/+) mice. In addition, Sepp1(-/-) mice gavaged with (75)SeO(2-)(3) excreted 1.7 to 2.4 times as much of the (75)Se in the urine as did Sepp1(+/+) mice. These findings demonstrate that deletion of selenoprotein P raises urinary excretion of selenium. When urinary small-molecule (75)Se was injected intravenously into mice, over 90% of the (75)Se appeared in the urine within 24 h, regardless of selenium status. This shows that urinary selenium is dedicated to excretion and not to utilization by tissues. Our results indicate that deletion of selenoprotein P leads to increased urinary selenium excretion. We propose that the absence of selenoprotein P synthesis in the liver makes more selenium available for urinary metabolite synthesis, increasing loss of selenium from the organism and causing the decrease in whole-body selenium and some of the decreases observed in tissues of Sepp1(-/-) mice.
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Affiliation(s)
- Raymond F Burk
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232-0252, USA.
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Burk RF, Norsworthy BK, Motley AK, Hill KE. Response of Plasma Selenoproteins to Selenium Supplementation in Patients with Cirrhosis. FASEB J 2006. [DOI: 10.1096/fasebj.20.5.a1067-c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Raymond F Burk
- Medicine/GIVanderbilt University2215B Garland AvenueNashvilleTN37232‐0252
| | | | - Amy K Motley
- Medicine/GIVanderbilt University2215B Garland AvenueNashvilleTN37232‐0252
| | - Kristina E Hill
- Medicine/GIVanderbilt University2215B Garland AvenueNashvilleTN37232‐0252
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Hill KE, Whitin JC, Austin LM, Motley AK, Burk RF, Cohen HJ. Deletion of GPX3 Affects Glutathione Metabolism. FASEB J 2006. [DOI: 10.1096/fasebj.20.5.a1068-a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Kristina E Hill
- Medicine/GIVanderbilt University2215B Garland AveNashvilleTN37232‐0252
| | - John C Whitin
- PediatricsStanford University300 Pasteur DrivePalo AltoCA94305‐5208
| | - Lori M Austin
- Medicine/GIVanderbilt University2215B Garland AveNashvilleTN37232‐0252
| | - Amy K Motley
- Medicine/GIVanderbilt University2215B Garland AveNashvilleTN37232‐0252
| | - Raymond F Burk
- Medicine/GIVanderbilt University2215B Garland AveNashvilleTN37232‐0252
| | - Harvey J Cohen
- PediatricsStanford University300 Pasteur DrivePalo AltoCA94305‐5208
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Motley AK, Hill KE, Zhou J, Austin LM, Olson GE, Atkins JF, Gesteland RF, Burk RF. The C‐terminal Domain of Selenoprotein P Is Needed for Maintenance of Selenium Homeostasis. FASEB J 2006. [DOI: 10.1096/fasebj.20.5.a1067-b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Amy K Motley
- Vanderbilt University2215B Garland AveNashvilleTN37232‐0252
| | | | - Jiadong Zhou
- University of Utah15 N 2030 ESalt Lake CityUT84112‐5330
| | - Lori M Austin
- Vanderbilt University2215B Garland AveNashvilleTN37232‐0252
| | - Gary E Olson
- Vanderbilt University2215B Garland AveNashvilleTN37232‐0252
| | - John F Atkins
- University of Utah15 N 2030 ESalt Lake CityUT84112‐5330
| | | | - Raymond F Burk
- Vanderbilt University2215B Garland AveNashvilleTN37232‐0252
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Abstract
Brain function and selenium concentration are well maintained in rodents under conditions of selenium deficiency. Recently, however, targeted deletion of the selenoprotein P gene (Sepp) has been associated with a decrease in brain selenium concentration and with neurological dysfunction. Studies were conducted with Sepp(-/-) and Sepp(+/+) mice to characterize the neurological dysfunction and to correlate it with dietary selenium level. When weanling Sepp(-/-) mice were fed the basal diet (<0.01 mg/kg selenium) supplemented with 0, 0.05 or 0.10 mg selenium/kg, they developed spasticity that progressed and required euthanasia. Supplementing the diet with > or =0.25 mg selenium/kg prevented the neurological dysfunction. To determine whether neurological dysfunction would occur in more mature Sepp(-/-) mice deprived of selenium, Sepp(-/-) mice that had been fed the basal diet supplemented with 1.0 mg selenium/kg for 4 wk were switched to a selenium-deficient diet. Within 3 wk they had developed neurological dysfunction and weight loss. At 3 wk, the 1.0 mg selenium/kg diet was reinstituted. Neurological function stabilized but did not return to normal. Brain selenium concentration did not increase. Weight gain resumed. This study shows that neurological dysfunction occurs when selenium supply to the brain is curtailed and that the dysfunction is not readily reversible. Both the absence of selenoprotein P and a low dietary selenium supply are necessary for the dysfunction to occur, indicating that selenoprotein P and at least one other form of selenium supply the element to the brain.
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Affiliation(s)
- Kristina E Hill
- Division of Gastroenterology and Clinical Nutrition Research Unit, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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Abstract
BACKGROUND On the basis of in vitro studies, the antioxidant nutrients vitamins E and C are postulated to interact in vivo. OBJECTIVE We developed a guinea pig model to evaluate the combined deficiency of vitamins E and C in vivo. DESIGN Weanling guinea pigs were fed a control diet or a vitamin E-deficient diet for 14 d, after which one-half of each group had vitamin C removed from their diet, thus creating 4 diet groups. Some animals were observed for clinical signs. Others were killed for evaluation. RESULTS Of 21 guinea pigs that were observed after being fed the diet deficient in both vitamins, 8 died 9 +/- 2 d (x +/- SD) after starting the diet. Eight additional guinea pigs developed a characteristic syndrome at 11 +/- 3 d. First, they became paralyzed in the hind limbs. Within a few hours, the paralysis progressed to include all 4 limbs and caused difficulty in breathing, which would have caused death had the animals not been euthanized. Histopathologic evaluation did not identify a lesion in the muscles or nervous system that could account for the paralysis. Biochemical measurements confirmed the deficiencies and indicated that the double deficiency caused lipid peroxidation in the central nervous system. CONCLUSIONS A distinct clinical syndrome of combined vitamin E and vitamin C deficiency occurs in guinea pigs. This syndrome indicates that these antioxidant vitamins are related in vivo. We speculate that acute oxidative injury in the central nervous system underlies the clinical syndrome.
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Affiliation(s)
- Kristina E Hill
- Division of Gastroenterology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN, USA
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Abstract
Biological functions of selenium are exerted by selenoproteins that contain selenocysteine in their primary structure. Selenocysteine is synthesized and inserted into proteins cotranslationally by a complex process. Families of selenoproteins include the glutathione peroxidases, the iodothyronine deiodinases and the thioredoxin reductases. These are redox enzymes that take advantage of the chemical properties of selenium to catalyze, respectively, removal of hydroperoxides by glutathione, deiodination of thyroid hormones and support of cellular processes requiring reduction of disulfides. Approximately 10 additional selenoproteins have been identified. One of them, selenoprotein P, is an extracellular protein that contains most of the selenium in plasma. It associates with endothelial cells, probably through its heparin-binding properties. Selenoprotein P has been postulated to protect against oxidative injury and to transport selenium from the liver to peripheral tissues. Selenium-dependent protection against diquat-induced liver necrosis and lipid peroxidation in the rat correlates with the presence of selenoprotein P. Recent results support a transport function. When (75)SeO(3)(2-) was administered intravenously to rats, liver tissue took up (75)Se within minutes, associated with a rapid decline in plasma (75)Se. Brain tissue did not begin accumulating (75)Se until (75)Se-labeled selenoprotein P had begun appearing in the plasma after 30 min. These results suggest that tissues like liver can take up small-molecule forms of selenium whereas presence of the element in selenoprotein P facilitates uptake by tissues like brain. Thus, there is evidence for both antioxidant and selenium transport functions of selenoprotein P.
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Affiliation(s)
- Raymond F Burk
- Division of Gastroenterology, Department of Medicine and Clinical Nutrition Research Unit, Vanderbilt University School of Medicine, Nashville, TN 37232-2279, USA.
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Hill KE, Zhou J, McMahan WJ, Motley AK, Atkins JF, Gesteland RF, Burk RF. Deletion of selenoprotein P alters distribution of selenium in the mouse. J Biol Chem 2003; 278:13640-6. [PMID: 12574155 DOI: 10.1074/jbc.m300755200] [Citation(s) in RCA: 331] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Selenoprotein P (Se-P) contains most of the selenium in plasma. Its function is not known. Mice with the Se-P gene deleted (Sepp(-/-)) were generated. Two phenotypes were observed: 1) Sepp(-/-) mice lost weight and developed poor motor coordination when fed diets with selenium below 0.1 mg/kg, and 2) male Sepp(-/-) mice had sharply reduced fertility. Weanling male Sepp(+/+), Sepp(+/-), and Sepp(-/-) mice were fed diets for 8 weeks containing <0.02-2 mg selenium/kg. Sepp(+/+) and Sepp(+/-) mice had similar selenium concentrations in all tissues except plasma where a gene-dose effect on Se-P was observed. Liver selenium was unaffected by Se-P deletion except that it increased when dietary selenium was below 0.1 mg/kg. Selenium in other tissues exhibited a continuum of responses to Se-P deletion. Testis selenium was depressed to 19% in mice fed an 0.1 mg selenium/kg diet and did not rise to Sepp(+/+) levels even with a dietary selenium of 2 mg/kg. Brain selenium was depressed to 43%, but feeding 2 mg selenium/kg diet raised it to Sepp(+/+) levels. Kidney was depressed to 76% and reached Sepp(+/+) levels on an 0.25 mg selenium/kg diet. Heart selenium was not affected. These results suggest that the Sepp(-/-) phenotypes were caused by low selenium in testis and brain. They strongly suggest that Se-P from liver provides selenium to several tissues, especially testis and brain. Further, they indicate that transport forms of selenium other than Se-P exist because selenium levels of all tissues except testis responded to increases of dietary selenium in Sepp(-/-) mice.
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Affiliation(s)
- Kristina E Hill
- Division of Gastroenterology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
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Abstract
Selenium and vitamin E deficiencies were studied as part of an evaluation of oxidant defenses in guinea pigs. Male guinea pigs (100-120 g) were fed a control diet (C) or the diet without selenium (0 Se), without vitamin E (0 E), or without either selenium or vitamin E (0 Se-0 E). Between d 30 and 35, 7 of 13 guinea pigs fed the 0 Se-0 E diet were euthanized because of severe weakness of their extremities. No guinea pigs in the other diet groups developed weakness. Guinea pigs from each group were killed on d 37. Selenium deficiency and vitamin E deficiency were verified by measurement of glutathione peroxidase and alpha-tocopherol. Creatine phophokinase (CPK) activity was greater than controls in both groups fed vitamin E-deficient diets, but the increase was greater in the 0 Se-0 E group than in the 0 E group. Muscle F(2)-isoprostanes were greater than controls in both groups fed vitamin E-deficient diets with the level in the 0 Se-0 E group greater than that in the 0 E group. Histologic muscle necrosis was severe in the 0 Se-0 E group, minimal in the 0 E group and absent from other groups. The diets used in this study induced selenium and vitamin E deficiencies in guinea pigs. The study demonstrates that combined selenium and vitamin E deficiency results in a fatal myopathy in guinea pigs that is associated with lipid peroxidation in the affected muscle. This nutritional myopathy is much more severe than the myopathy that occurs with vitamin E deficiency alone.
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Affiliation(s)
- K E Hill
- Divisions of Gastroenterology and Endocrinology, Department of Medicine and Clinical Nutrition Research Unit, Vanderbilt University School of Medicine, Nashville, TN 37232-2279, USA.
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Abstract
Selenium is present in plasma and tissues in specific and non-specific forms. The experiments reported here were carried out to clarify some factors that affect these forms of the element in plasma. A selenium-replete human subject was given 400 microg of selenium daily for 28 days as selenomethionine and, in a separate experiment, as selenate. The selenomethionine raised plasma and albumin selenium concentrations. Selenate did neither. The molar ratio of methionine to selenium in albumin was approximately 8000 under basal and selenate-supplemented conditions but 2800 after selenomethionine supplementation. This demonstrates that selenium from selenomethionine, but not selenium from selenate, can be incorporated into albumin, presumably as selenomethionine in the methionine pool. Selenocysteine incorporation into albumin was studied in rats using (75)Se-selenocysteine. No evidence was obtained for incorporation of (75)Se into albumin after exogenous administration or endogenous synthesis of (75)Se-selenocysteine. Thus, selenocysteine does not appear to be incorporated non-specifically into proteins as is selenomethionine. These findings are in support of selenomethionine being a non-specific form of selenium that is metabolized as a constituent of the methionine pool and is unaffected by specific selenium metabolic processes. No evidence was found for non-specific incorporation of selenium into plasma proteins when it was administered as selenate or as selenocysteine. These forms of the element appear to be metabolized by specific selenium metabolic processes.
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Affiliation(s)
- R F Burk
- Division of Gastroenterology, Department of Medicine and Clinical Nutrition Research Unit, Vanderbilt University School of Medicine, Nashville, TN 37221, USA.
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Hondal RJ, Motley AK, Hill KE, Burk RF. Failure of selenomethionine residues in albumin and immunoglobulin G to protect against peroxynitrite. Arch Biochem Biophys 1999; 371:29-34. [PMID: 10525286 DOI: 10.1006/abbi.1999.1435] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Selenomethionine has been suggested to protect against peroxynitrite by quenching it in vivo. Selenomethionine is distributed randomly in the methionine pool. Albumin and IgG were purified from plasma of a human being before and after 28 days of supplementation with 400 microg selenium/day as selenomethionine. The albumin contained 1 selenium atom, presumably as selenomethionine, per 8000 methionine residues before supplementation and 1 per 2800 after supplementation. Although this ratio suggested that selenomethionine would not have as great an effect in quenching peroxynitrite as would methionine, direct testing of the albumin and IgG fractions was carried out to assess the ability of these proteins to prevent peroxynitrite oxidation of dihydrorhodamine 123 to rhodamine 123. The ability of the albumin preparations to resist nitration of tyrosine residues was also assessed. The high-selenomethionine preparations of the proteins had no greater effect in quenching the peroxynitrite than did the normal-selenomethionine preparations. These results do not support the proposal that selenomethionine in proteins contributes to in vivo protection against peroxynitrite.
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Affiliation(s)
- R J Hondal
- Department of Medicine and Clinical Nutrition Research Unit, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
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