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Abstract
Zinc is a trace mineral which is vital for the functioning of numerous cellular processes, is critical for growth, and may play an important role in cancer etiology and outcome. The intracellular levels of this mineral are regulated through the coordinated expression of zinc transporters, which modulate both zinc influx as well as efflux. LIV-1 (ZIP6) was first described in 1988 as an estrogen regulated gene with later work suggesting a role for this transporter in cancer growth and metastasis. Despite evidence of its potential utility as a target gene for cancer prognosis and treatment, LIV-1 has received relatively little attention, with only three prior reviews being published on this topic. Herein, the physiological effects of zinc are reviewed in light of this mineral’s role in cancer growth with specific attention being given to LIV-1 and the potential importance of this transporter to breast cancer etiology.
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Affiliation(s)
- Bruce J. Grattan
- Department of Family Medicine, Stony Brook University Hospital Medical Center, Stony Brook, New York, NY 11597, USA
- Authors to whom correspondence should be addressed; (B.J.G.); (H.C.F.); Tel.: +1-631-444-8245; Fax: +1-631-444-7552
| | - Hedley C. Freake
- Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06268, USA
- Authors to whom correspondence should be addressed; (B.J.G.); (H.C.F.); Tel.: +1-631-444-8245; Fax: +1-631-444-7552
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Sankavaram K, Freake HC. The effects of transformation and ZnT-1 silencing on zinc homeostasis in cultured cells. J Nutr Biochem 2012; 23:629-34. [DOI: 10.1016/j.jnutbio.2011.03.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2010] [Revised: 09/21/2010] [Accepted: 03/03/2011] [Indexed: 01/08/2023]
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Dutta A, Sankavaram K, Chong L, Palermo A, Michel RG, Freake HC. Rapid homeostatic response of H4IIE cells to diethylenetriaminepentaacetic acid is not due to changes in the amount or localization of ZnT-1 protein. Nutr Res 2011; 31:404-11. [DOI: 10.1016/j.nutres.2011.05.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 04/29/2011] [Accepted: 05/02/2011] [Indexed: 10/18/2022]
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Sankavaram K, Chong L, Mah E, Bruno RS, Freake HC. The Effects of Extracellular Zinc Depletion on Zinc Homeostasis and Oxidative Stress Responses in Cancer Cell Lines. FASEB J 2011. [DOI: 10.1096/fasebj.25.1_supplement.228.2] [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)
- Kavitha Sankavaram
- Laboratory of Experimental GerontologyNational Institute on AgingBaltimoreMD
| | - Leelyn Chong
- Nutritional SciencesUniversity of ConnecticutStorrsCT
| | - Eunice Mah
- Nutritional SciencesUniversity of ConnecticutStorrsCT
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Chong L, Sankavaram K, Freake HC. LIV‐1 regulates zinc uptake and E‐cadherin (CDH1) expression in MDA‐MB‐231 breast cancer cells but does not influence SNAI1. FASEB J 2011. [DOI: 10.1096/fasebj.25.1_supplement.979.2] [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)
- Leelyn Chong
- Nutritional SciencesUniversity of ConnecticutStorrsCT
| | - Kavitha Sankavaram
- Laboratory of Experimental GerontologyNational Institute on AgingBaltimoreMD
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Pasiakos SM, Vislocky LM, Carbone JW, Altieri N, Konopelski K, Freake HC, Anderson JM, Ferrando AA, Wolfe RR, Rodriguez NR. Acute energy deprivation affects skeletal muscle protein synthesis and associated intracellular signaling proteins in physically active adults. J Nutr 2010; 140:745-51. [PMID: 20164371 DOI: 10.3945/jn.109.118372] [Citation(s) in RCA: 104] [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: 11/14/2022] Open
Abstract
To date, few studies have characterized the influence of energy deprivation on direct measures of skeletal muscle protein turnover. In this investigation, we characterized the effect of an acute, moderate energy deficit (10 d) on mixed muscle fractional synthetic rate (FSR) and associated intracellular signaling proteins in physically active adults. Eight men and 4 women participated in a 20-d, 2-phase diet intervention study: weight maintenance (WM) and energy deficient (ED; approximately 80% of estimated energy requirements). Dietary protein (1.5 g x kg(-1) x d(-1)) and fat (approximately 30% of total energy) were constant for WM and ED. FSR and intracellular signaling proteins were measured on d 10 of both interventions using a primed, constant infusion of [(2)H(5)]-phenylalanine and Western blotting techniques, respectively. Participants lost approximately 1 kg body weight during ED (P < 0.0001). FSR was reduced approximately 19% (P < 0.05) for ED (0.06 +/- 0.01%/h) compared with WM (0.074 +/- 0.01%/h). Protein kinase B and eukaryotic initiation factor 4E binding protein 1 phosphorylation were lower (P < 0.05) during ED compared with WM. AMP activated protein kinase phosphorylation decreased (P < 0.05) over time regardless of energy status. These findings show that FSR and associated synthetic intracellular signaling proteins are downregulated in response to an acute, moderate energy deficit in physically active adults and provide a basis for future studies assessing the impact of prolonged, and perhaps more severe, energy restriction on skeletal muscle protein turnover.
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Affiliation(s)
- Stefan M Pasiakos
- Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, USA
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Chong L, Sankavaram K, Freake HC. The regulation of LIV‐1 mRNA in MDA‐MB‐231 human breast cancer cells and its association with E‐cadherin. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.928.5] [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)
- Leelyn Chong
- Department of Nutritional SciencesUniversity of ConnecticutStorrsCT
| | | | - Hedley C Freake
- Department of Nutritional SciencesUniversity of ConnecticutStorrsCT
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Sankavaram K, Freake HC. The Effects of Transformation and ZnT‐1 Silencing on Zinc Homeostasis in Cultured Cells. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.718.1] [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]
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Sankavaram K, Chong L, Bruno RS, Freake HC. Zinc Deficiency Induces Apoptosis but Zinc Induces Necrosis in Rat Hepatoma Cells. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.718.3] [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)
| | - Leelyn Chong
- Nutritional SciencesUniversity of ConnecticutStorrsCT
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Vislocky LM, Pasiakos SM, Carbone JW, Freake HC, Anderson JM, Ferrando AA, Wolfe RR, Rodriguez NR. Post-exercise Skeletal Muscle Protein Synthesis And Intracellular Signals During Negative Energy Balance In Active Adults. Med Sci Sports Exerc 2009. [DOI: 10.1249/01.mss.0000354102.40656.ce] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Sankavaram K, Grattan BJ, Freake HC. Effects of DTPA on zinc flux in leukemia cell lines. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.922.6] [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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McGonagle A, Winston J, Barnes‐Farrell J, Freake HC. Factors associated with academic success in the sciences. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.632.16] [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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Sankavaram K, Grattan BJ, Walker R, Park HJ, Freake HC. Effects of altered zinc availability on proliferation and oxidative stress in cultured cells. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.216.2] [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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Pasiakos SM, Vislocky LM, Carbone JW, Freake HC, Anderson JM, Ferrando AA, Wolfe RR, Rodriguez NR. Energy‐induced changes in skeletal muscle protein synthesis and molecular signaling in physically active adults. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.541.2] [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)
| | | | | | | | | | - Arny A Ferrando
- Center for Translational Research in Aging & LongevityDonald W. Reynolds Institute on Aging and University of Arkansas for Medical SciencesLittle RockAR
| | - Robert R Wolfe
- Center for Translational Research in Aging & LongevityDonald W. Reynolds Institute on Aging and University of Arkansas for Medical SciencesLittle RockAR
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Grattan BJ, Sankavaram K, Freake HC. Regulation of LIV‐1 expression in breast cancer cells. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.897.25] [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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Dutta A, Schaller M, Franco AT, Sankavaram K, Grattan BJ, Freake HC. Zinc retention differs between primary and transformed cells in response to zinc deprivation. J Nutr Biochem 2009; 21:162-70. [PMID: 19269154 DOI: 10.1016/j.jnutbio.2008.12.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2008] [Revised: 11/26/2008] [Accepted: 12/03/2008] [Indexed: 11/19/2022]
Abstract
Previous studies in our laboratory have demonstrated that reducing the availability of zinc with the extracellular metal chelator DTPA (diethylenetriaminepentaacetate) enhances, rather than inhibits, the thyroid hormone induction of growth hormone mRNA in GH3 rat anterior pituitary tumor cells. To understand the actions of the chelator on cellular zinc status, we observed the effects of DTPA on (65)Zn uptake and retention. DTPA reduced the uptake of (65)Zn by GH3 cells from the medium, but when GH3 cells were prelabeled with (65)Zn, it resulted in greater retention of the isotope. In primary hepatocytes, DTPA both reduced the uptake of (65)Zn from the medium and increased efflux from prelabeled cells. To investigate this difference, we studied the effects of DTPA on radioactive zinc flux in the H4IIE (rat hepatoma), MCF-7 (human breast cancer) and Hs578Bst (nontransformed human mammary) cell lines and in rat primary anterior pituitary cells. DTPA reduced the uptake of (65)Zn in all cell lines examined. DTPA increased the retention of (65)Zn in prelabeled H4IIE, MCF-7 and Hs578Bst cells but reduced it in primary pituitary cells. Time course experiments showed that (65)Zn efflux is shut down rapidly by DTPA in transformed cells, whereas the chelator causes greater efflux from primary hepatocytes over the first 6 h. Experiments with (14)C-labeled DTPA confirmed that this chelator does not cross cell membranes, showing that it operates entirely within the medium. Expression of ZnT-1, the efflux transporter, was not affected by DTPA in H4IIE cells. Thus, zinc deprivation enhanced zinc retention in established cell lines but increased efflux from primary cells, perhaps reflecting differing requirements for this mineral.
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Affiliation(s)
- Amrita Dutta
- Department of Nutritional Sciences, University of Connecticut, CT 06269-4017, USA
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Dutta A, Sankavaram K, Grattan B, Freake HC. ZnT‐1 protein expression or localization does not explain effects of reduced availability of zinc on cellular zinc efflux. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.697.8] [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)
- Amrita Dutta
- Nutritional SciencesUniversity of ConnecticutStorrsCT
| | | | - Bruce Grattan
- Nutritional SciencesUniversity of ConnecticutStorrsCT
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Torres-Gonzalez M, Shrestha S, Sharman M, Freake HC, Volek JS, Fernandez ML. Carbohydrate restriction alters hepatic cholesterol metabolism in guinea pigs fed a hypercholesterolemic diet. J Nutr 2007; 137:2219-23. [PMID: 17885001 DOI: 10.1093/jn/137.10.2219] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The current study was undertaken to evaluate the effect of carbohydrate restriction on hepatic cholesterol metabolism in guinea pigs fed a hypercholesterolemic diet. Hartley male guinea pigs (n = 10 per group) were fed 1 of 3 diets: a diet with a percent energy distribution of 42:23:35 carbohydrate:protein:fat and 0.04% cholesterol (control), a diet with the same macronutrient distribution but with 0.25% cholesterol (HChol), or a carbohydrate-restricted (CR) diet with a percent energy distribution of 11:30:59 carbohydrate:protein:fat and 0.25% cholesterol for 12 wk. There was more accumulation of hepatic cholesterol and triglycerides as well as lower 3-hydroxy-3-methyl glutaryl-CoA reductase messenger RNA abundance in guinea pigs fed the high-cholesterol diets (HChol and CR) (P < 0.01). Guinea pigs fed the CR diet had lower concentrations of hepatic total cholesterol and cholesteryl ester than those fed the HChol diet (P < 0.05). There was no diet effect on hepatic LDL receptor expression. Hepatic acyl CoA cholesteryl acyltransferase (ACAT) activity was lowest in guinea pigs fed the low-cholesterol diet (9.7 +/- 4.8 pmol.min(-1).mg(-1)), intermediate in those fed the CR diet (37.3 +/- 12.4 pmol.min(-1).mg protein(-1)), and highest in guinea pigs fed the HChol diet (55.9 +/- 11.2 pmol.min(-1).mg(-1)). ACAT activity was significantly correlated with hepatic cholesterol (r = 0.715; P < 0.01) and LDL cholesterol (r = 0.59; P < 0.01) for all dietary groups, suggesting a major role of this enzyme in hepatic cholesterol homeostasis and in lipoprotein concentrations. These results indicate that dietary cholesterol increases hepatic lipid accumulation and affects hepatic cholesterol homeostasis. Carbohydrate restriction in the presence of high cholesterol is associated with lower hepatic ACAT activity and an attenuation of hepatic cholesterol accumulation.
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Shrestha S, Freake HC, McGrane MM, Volek JS, Fernandez ML. A combination of psyllium and plant sterols alters lipoprotein metabolism in hypercholesterolemic subjects by modifying the intravascular processing of lipoproteins and increasing LDL uptake. J Nutr 2007; 137:1165-70. [PMID: 17449576 DOI: 10.1093/jn/137.5.1165] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We previously demonstrated that a diet therapy involving consumption of 7.28 g psyllium (PSY) and 2 g of plant sterols (PS) per day reduced LDL cholesterol from 3.6 +/- 0.7 to 3.1 +/- 0.8 mmol/L (P < 0.01) and decreased the number of intermediate density lipoprotein particles and the smaller LDL and HDL subfractions in hypercholesterolemic individuals (n = 33). The study design was a randomized double blind crossover. Subjects consumed either 2 test cookies containing PSY+PS or 2 placebo cookies for 1 mo with a 3-wk wash out between treatments. To explore mechanisms of the lipid-lowering effects of combined PSY+PS, we present data related to intravascular and molecular regulation. Intake of PSY+PS decreased the cholesterol concentration in LDL-1 from 2.46 +/- 0.66 to 2.26 +/- 0.46 mmol/L and in LDL-2 from 0.63 +/- 0.24 to 0.54 +/- 0.27 mmol/L (P < 0.05) in the test compared with the placebo period. An increase in LDL peak size from 27.3 +/- 0.8 to 27.5 +/- 0.6 nm (P < 0.05) and a decrease in the prevalence of LDL pattern B from 27 to 18% (P < 0.05) also occurred during the PSY+PS period. Cholesteryl ester transfer protein activity was 11% lower (P < 0.05) during the test period. Notably, the abundance of the LDL receptor in circulating mononuclear cells as measured by real time PCR was 26% higher during the test compared with the placebo period (P < 0.03). These results indicate that the hypocholesterolemic action of PSY and PS can be explained in part by modifications in the intravascular processing of lipoproteins and by increases in LDL receptor-mediated uptake.
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Affiliation(s)
- Sudeep Shrestha
- Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, USA
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Shrestha S, Freake HC, McGrane MM, Fernandez ML. A combination nutritional therapy of psyllium (PSY) and plant sterols (PS) reduced plasma LDL‐C concentrations in hypercholesterolemic subjects by decreasing cholesteryl ester protein (CETP) activity and upregulating the LDL receptor. FASEB J 2007. [DOI: 10.1096/fasebj.21.5.a156-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)
- Sudeep Shrestha
- Nutritional SciencesUniversity of Connecticut3624 Horsebarn Road ExtStorrsCT06269
| | - Hedley C Freake
- Nutritional SciencesUniversity of Connecticut3624 Horsebarn Road ExtStorrsCT06269
| | - Mary M McGrane
- Nutritional SciencesUniversity of Connecticut3624 Horsebarn Road ExtStorrsCT06269
| | - Maria Luz Fernandez
- Nutritional SciencesUniversity of Connecticut3624 Horsebarn Road ExtStorrsCT06269
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Dutta A, Grattan B, Sankavaram K, Freake HC. Cultured cells differ in their homeostatic response to zinc deprivation. FASEB J 2007. [DOI: 10.1096/fasebj.21.5.a170-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)
- Amrita Dutta
- Nutritional SciencesUniversity of Connecticut3624 Horsebarn Rd ExtStorrsCT06269‐4017
| | - Bruce Grattan
- Nutritional SciencesUniversity of Connecticut3624 Horsebarn Rd ExtStorrsCT06269‐4017
| | - Kavitha Sankavaram
- Nutritional SciencesUniversity of Connecticut3624 Horsebarn Rd ExtStorrsCT06269‐4017
| | - Hedley C Freake
- Nutritional SciencesUniversity of Connecticut3624 Horsebarn Rd ExtStorrsCT06269‐4017
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Torres‐Gonzalez M, Volek JS, Freake HC, Fernandez ML. Carbohydrate restriction reduces hepatic cholesterol accumulation and acyl CoA cholesteryl acyltransferase (ACAT) activity induced by high levels of dietary cholesterol. FASEB J 2007. [DOI: 10.1096/fasebj.21.5.a101] [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)
| | - Jeff S Volek
- KinesiologyUniversity of Connecticut249 Glenbrook RoadStorrsCT06269
| | - Hedley C Freake
- Nutritional SciencesUniversity of Connecticut3624 Horsebarn Rd ExtStorrsCT06269
| | - Maria Luz Fernandez
- Nutritional SciencesUniversity of Connecticut3624 Horsebarn Rd ExtStorrsCT06269
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Dutta A, Sankavaram K, Grattan B, Freake HC. Rapid homeostatic response of H4IIE cells to zinc deprivation is not due to changes in total amount of ZnT‐1 protein. FASEB J 2007. [DOI: 10.1096/fasebj.21.6.a1108-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)
- Amrita Dutta
- Nutritional SciencesUniversity of Connecticut3624 Horsebarn Rd ExtStorrsCT06269‐4017
| | - Kavitha Sankavaram
- Nutritional SciencesUniversity of Connecticut3624 Horsebarn Rd ExtStorrsCT06269‐4017
| | - Bruce Grattan
- Nutritional SciencesUniversity of Connecticut3624 Horsebarn Rd ExtStorrsCT06269‐4017
| | - Hedley C Freake
- Nutritional SciencesUniversity of Connecticut3624 Horsebarn Rd ExtStorrsCT06269‐4017
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Aggarwal D, Freake HC, Soliman GA, Dutta A, Fernandez ML. Validation of using gene expression in mononuclear cells as a marker for hepatic cholesterol metabolism. Lipids Health Dis 2006; 5:22. [PMID: 16911794 PMCID: PMC1564017 DOI: 10.1186/1476-511x-5-22] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [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: 07/14/2006] [Accepted: 08/15/2006] [Indexed: 11/30/2022] Open
Abstract
HMG-CoA reductase and the LDL receptor are ubiquitously expressed in major tissues. Since the liver plays a major role in regulating circulating LDL, it is usually of interest to measure the effects of drug or dietary interventions on these proteins in liver. In humans, peripheral blood mononuclear cells have been used as a surrogate for liver to assess regulation of these genes, although there is concern regarding the validity of this approach. The purpose of this study was to evaluate the relationship between liver and mononuclear cell expression of HMG-CoA reductase and the LDL receptor in guinea pigs, a well established model for human cholesterol and lipoprotein metabolism. We extracted RNA from liver and mononuclear cells of guinea pigs from a previous study where the effects of rapamycin, an immunosuppresant drug used for transplant patients, on lipid metabolism were evaluated. Guinea pigs were assigned to three different diets containing the same amount of fat (15 g/100 g) and cholesterol (0.08 g/100 g) for a period of 3 weeks. The only difference among diets was the concentration of rapamycin: 0, 0.0028 or 0.028 g/100 g. There were no differences in plasma LDL cholesterol (LDL-C) among groups. Values were 78.4 ± 14.3, 65.8 ± 17.2 and 68.4 ± 45.4 mg/dL (P > 0.05) for guinea pigs treated with 0, low or high doses of rapamycin, respectively. The mRNA abundance for the LDL receptor and HMG-CoA reductase was measured both in liver (n = 30) and mononuclear cells (n = 22) using reverse transcriptase PCR. In agreement with the finding of no changes in plasma LDL-C, there were also no differences for the expression of HMG-CoA reductase or the LDL receptor among groups. However, a positive correlation was found between liver and mononuclear cells for both HMG-CoA reductase (r = 0.613, P < 0.01) and the LDL receptor (r = 0.622, P < 0.01). These correlations suggest that monocytes can be used in humans as an index for liver to assess diet and drug effects on the expression of HMG-CoA reductase and the LDL receptor.
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Affiliation(s)
- Dimple Aggarwal
- Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, USA
| | - Hedley C Freake
- Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, USA
| | - Ghada A Soliman
- Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine, University of Michigan Medical School Ann Arbor, Michigan, 48109, USA
| | - Amrita Dutta
- Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, USA
| | - Maria-Luz Fernandez
- Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, USA
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Abstract
Zinc is the second most abundant transition metal in the human body, fulfilling a multitude of biological roles, but the mechanisms underlying its physiology are poorly understood. The lack of knowledge is, in part, due to the hitherto limited techniques available to track zinc in biological systems. The recent emergence of a number of zinc-specific molecular sensors has provided a new tool to image zinc in live cells and tissue samples. This contribution highlights the concepts behind using zinc-specific fluorescent molecular sensors to gain information about zinc action in biological samples, and provides representative examples of images recorded.
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Affiliation(s)
- Nathaniel C Lim
- Department of Chemistry, University of Connecticut, Storrs, CT 06269-3060, USA
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Gaine PC, Bolster DR, Ferrando AA, Wolfe RR, Vislocky LM, Freake HC, Rodriguez NR. The effects of endurance exercise on skeletal muscle intracellular signaling events. FASEB J 2006. [DOI: 10.1096/fasebj.20.4.a169-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)
- P. Courtney Gaine
- Nutritional SciencesUniversity of Connecticut3624 Horsebarn Hill Rd Ext, U‐4017StorrsCT06269
| | - Douglas R. Bolster
- Division of Space Life SciencesUniversities Space Research Association (USRA)3600 Bay Area BoulevardHoustonTX77058
| | - Arny A Ferrando
- Departments of SurgeryUTMB301 University BoulevardGalvestonTX77555
| | - Robert R. Wolfe
- Departments of SurgeryUTMB301 University BoulevardGalvestonTX77555
| | - Lisa M. Vislocky
- Nutritional SciencesUniversity of Connecticut3624 Horsebarn Hill Rd Ext, U‐4017StorrsCT06269
| | - Hedley C. Freake
- Nutritional SciencesUniversity of Connecticut3624 Horsebarn Hill Rd Ext, U‐4017StorrsCT06269
| | - Nancy R. Rodriguez
- Nutritional SciencesUniversity of Connecticut3624 Horsebarn Hill Rd Ext, U‐4017StorrsCT06269
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Aggarwal D, Freake HC, Soliman GA, Dutta A, Fernandez M. Correlation between liver and monocyte expression of the LDL receptor and HMG‐CoA reductase in guinea pigs. FASEB J 2006. [DOI: 10.1096/fasebj.20.5.lb82] [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)
- Dimple Aggarwal
- Nutritional SciencesUniversity of Connecticut3624 Horsebarn Road ExtStorrsCT06269
| | - Hedley C Freake
- Nutritional SciencesUniversity of Connecticut3624 Horsebarn Road ExtStorrsCT06269
| | - Ghada A Soliman
- Internal MedicineUniversity of MichiganDivision of Metabolism and EndocrinologyAnn ArborMI48109
| | - Amrita Dutta
- Nutritional SciencesUniversity of Connecticut3624 Horsebarn Road ExtStorrsCT06269
| | - Maria‐Luz Fernandez
- Nutritional SciencesUniversity of Connecticut3624 Horsebarn Road ExtStorrsCT06269
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29
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Zeisel SH, Freake HC, Bauman DE, Bier DM, Burrin DG, German JB, Klein S, Marquis GS, Milner JA, Pelto GH, Rasmussen KM. The nutritional phenotype in the age of metabolomics. J Nutr 2005; 135:1613-6. [PMID: 15987837 PMCID: PMC2430109 DOI: 10.1093/jn/135.7.1613] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [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: 11/14/2022] Open
Abstract
The concept of the nutritional phenotype is proposed as a defined and integrated set of genetic, proteomic, metabolomic, functional, and behavioral factors that, when measured, form the basis for assessment of human nutritional status. The nutritional phenotype integrates the effects of diet on disease/wellness and is the quantitative indication of the paths by which genes and environment exert their effects on health. Advances in technology and in fundamental biological knowledge make it possible to define and measure the nutritional phenotype accurately in a cross section of individuals with various states of health and disease. This growing base of data and knowledge could serve as a resource for all scientific disciplines involved in human health. Nutritional sciences should be a prime mover in making key decisions that include: what environmental inputs (in addition to diet) are needed; what genes/proteins/metabolites should be measured; what end-point phenotypes should be included; and what informatics tools are available to ask nutritionally relevant questions. Nutrition should be the major discipline establishing how the elements of the nutritional phenotype vary as a function of diet. Nutritional sciences should also be instrumental in linking the elements that are responsive to diet with the functional outcomes in organisms that derive from them. As the first step in this initiative, a prioritized list of genomic, proteomic, and metabolomic as well as functional and behavioral measures that defines a practically useful subset of the nutritional phenotype for use in clinical and epidemiological investigations must be developed. From this list, analytic platforms must then be identified that are capable of delivering highly quantitative data on these endpoints. This conceptualization of a nutritional phenotype provides a concrete form and substance to the recognized future of nutritional sciences as a field addressing diet, integrated metabolism, and health.
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Affiliation(s)
- S H Zeisel
- American Society for Nutritional Sciences Long Range Planning Committee, Bethesda, MD 20814-3990, USA.
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30
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Patalay M, Lofgren IE, Freake HC, Koo SI, Fernandez ML. The lowering of plasma lipids following a weight reduction program is related to increased expression of the LDL receptor and lipoprotein lipase. J Nutr 2005; 135:735-9. [PMID: 15795426 DOI: 10.1093/jn/135.4.735] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
To determine whether changes in plasma lipids following a weight loss program were related to modifications in gene expression of the LDL receptor (LDL-R), lipoprotein lipase (LPL), and 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase, overweight/obese premenopausal women were recruited. The 10-wk, randomized, double-blind intervention consisted of a hypoenergetic diet, high in protein (30% energy) and low in carbohydrate (40% energy), increased physical activity (number of steps taken per day), and intake of a supplement (carnitine or placebo). Our initial hypothesis was that carnitine would enhance the beneficial effects of weight loss on plasma lipids and anthropometrics. Because the carnitine and placebo groups did not differ in any of the measured variables, data for all subjects were pooled and comparisons were made between baseline and postintervention. Mean weight loss was 4.4 kg (P < 0.001), and plasma triglycerides (TG), total, and LDL cholesterol (LDL-C) were reduced by 31.8, 9.9, and 11.9%, respectively (P < 0.001). The expression of the genes of interest was measured in RNA extracted from mononuclear cells at baseline and postintervention using a semiquantitative RT-PCR method. Glyceraldehyde-3-phosphate dehydrogenase was used as an internal control. After 10 wk, there was a 25.7% increase in the abundance of LPL mRNA (P < 0.01) and a 27.7% increase in that of LDL-R mRNA (P < 0.01). The expression of HMG-CoA reductase was not altered by weight loss. The results suggest that the increased expression of the LDL-R and LPL after the intervention might have contributed to the lower plasma LDL-C and TG observed in these women.
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Affiliation(s)
- Madhu Patalay
- Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, USA
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31
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Lim NC, Schuster JV, Porto MC, Tanudra MA, Yao L, Freake HC, Brückner C. Coumarin-Based Chemosensors for Zinc(II): Toward the Determination of the Design Algorithm for CHEF-Type and Ratiometric Probes. Inorg Chem 2005; 44:2018-30. [PMID: 15762729 DOI: 10.1021/ic048905r] [Citation(s) in RCA: 259] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The synthesis of a series of coumarin-based chemosensor assemblies for zinc is detailed, using established and novel synthetic pathways. Variations of the nature of the chelating unit (DPA or cyclen), position of the attachment point of the chelating unit (3- or 4-position), and nature of the 7-substituent (-OH, -OAc, or -NR2) on the coumarin play a crucial role in whether, and to what extent, a CHEF-type or ratiometric response of the chemosensor is observed. Solvent effects are also discussed. The chemosensors were shown to be competent for detecting zinc pools in cultured rat pituitary (GH3) and hepatoma (H4IIE) cell lines. The work further defines the design algorithms for zinc-selective CHEF-type and ratiometric chemosensors.
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Affiliation(s)
- Nathaniel C Lim
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, USA
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32
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Kim YJ, Lee MS, Lee HJ, Wu Y, Freake HC, Chun HS, Kim Y. Hormones and Nutrients Regulate Acetyl-CoA Carboxylase Promoter I in Rat Primary Hepatocytes. J Nutr Sci Vitaminol (Tokyo) 2005; 51:124-8. [PMID: 16022200 DOI: 10.3177/jnsv.51.124] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
This study investigated the regulation of acetyl-CoA carboxylase (ACC) promoter activity by hormones and nutrients. Genomic clones including promoter I (PI) of the ACC gene were isolated and sequenced. ACC PI fragments (-1,049/+100 or -220/+21 bp) were subcloned into the pGL3-Basic vector that includes luciferase as a reporter gene. The ACC PI/luciferase chimeric plasmids were transfected into primary rat hepatocytes using lipofectin. Insulin treatment increased the activity of -1,049/+ 100 and -220/+21 ACC PI by 3.0- and 3.5-fold, respectively, compared to the control. The activity of both constructs was also increased by dexamethasone (Dex) and triiodothyronine (T3), with the greatest effects seen with all three hormones present. With -1,049/+100 or -220/+21 ACC PI, the addition of glucose increased luciferase activity compared to glucose-free control (p<0.05). On the other hand, polyunsaturated fatty acids (PUFA) reduced the activity of the -1,049/+100 ACC PI construct, with eicosapentaenoic acid and docosahexaenoic acid showing the greatest effect (about 70% of the control). However, the addition of PUFA to the culture media did not affect the activity of -220/+21 ACC PI. Therefore, insulin, Dex, T3, glucose, and PUFA regulate ACC gene expression, at least in part, through the PI promoter.
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Affiliation(s)
- Youn-Jung Kim
- Department of Food and Nutritional Sciences, Ewha Women's University, Daehyndong 11-1 Sudaemun-ku, Seoul, 120-750, Korea
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33
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German JB, Bauman DE, Burrin DG, Failla ML, Freake HC, King JC, Klein S, Milner JA, Pelto GH, Rasmussen KM, Zeisel SH. Metabolomics in the opening decade of the 21st century: building the roads to individualized health. J Nutr 2004; 134:2729-32. [PMID: 15465774 DOI: 10.1093/jn/134.10.2729] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
It is rapidly becoming possible to measure hundreds or thousands of metabolites in small samples of biological fluids or tissues. This makes it possible to assess the metabolic component of nutritional phenotypes and will allow individualized dietary recommendations. ASNS has to take action to ensure that appropriate technologies are developed and that metabolic databases are constructed with the right inputs and organization. The relations between diet and metabolomic profiles and between those profiles and health and disease must be established. ASNS also should consider the social implications of these advances and plan for their appropriate utilization.
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Affiliation(s)
- J B German
- American Society for Nutritional Sciences Long Range Planning Committee, USA
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34
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Sciaudone MP, Yao L, Schaller M, Zinn SA, Freake HC. Diethylenetriaminepentaacetic acid enhances thyroid hormone action by a transcriptional mechanism. Biol Trace Elem Res 2004; 99:219-31. [PMID: 15235154 DOI: 10.1385/bter:99:1-3:219] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2003] [Revised: 11/04/2003] [Accepted: 11/11/2003] [Indexed: 11/11/2022]
Abstract
Zinc is thought to be required as a structural component of the thyroid hormone (triiodothyronine, T3) receptor (TR). However, we have previously demonstrated that use of diethylenetriaminepentaacetic acid (DTPA) to restrict zinc availability to cultured cells actually potentiates rather than inhibits thyroid hormone action. In this article, the mechanisms underlying these effects of DTPA have been investigated. Treatment of GH3 rat pituitary tumor cells with DTPA in the presence of T3 resulted in twofold greater concentrations of growth hormone (GH) mRNA. Addition of actinomycin D to inhibit transcription showed that GH mRNA was actually less stable in the presence of DTPA, eliminating mRNA stabilization as a possible mechanism underlying this effect. Cycloheximide was able to block the induction by DTPA, showing a requirement for protein synthesis. Transient transfection of a GH promoter/luciferase reporter construct into GH3 cells revealed an inhibitory effect of DTPA on luciferase activity. However, when cells were stably transfected with the same construct, a T3-dependent stimulation of luciferase activity by DTPA was observed, mimicking the effects seen with the endogenous mRNA. Thus, the GH promoter does mediate the effects of DTPA, but stable integration into chromosomal material is required.
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Affiliation(s)
- Maria P Sciaudone
- Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269-4017, USA
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35
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Abstract
The synthesis of a coumarin-cyclen conjugate-based zinc-specific chemosensor and its ability to sense Zn(2+) in vitro is described. Using fluorescence microscopy, the chemosensor was shown to be capable of imaging Zn(2+) in live rat pituitary tumour cells.
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Affiliation(s)
- Nathaniel C Lim
- University of Connecticut, Department of Chemistry, 06269-3060, Storrs, CT, USA
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36
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Abstract
This paper is one in a series from the American Society of Nutritional Sciences Long Range Planning Committee, in which we are attempting to map out the implications of future directions in nutritional sciences for ASNS. Here, we address the area of social nutrition research and identify a series of orientations that are now emerging and likely to shape future research in this area. As with other areas of nutrition, a key feature is the importance of an integrated approach, both across social science disciplines and between social and biological scientists.
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Affiliation(s)
- Gretel H Pelto
- American Society for Nutritional Sciences, Bethesda, MD 20814-3990, USA
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37
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Vega-López S, Freake HC, Fernandez ML. Sex and hormonal status modulate the effects of psyllium on plasma lipids and monocyte gene expression in humans. J Nutr 2003; 133:67-70. [PMID: 12514268 DOI: 10.1093/jn/133.1.67] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Psyllium (PSY) intake decreases plasma LDL cholesterol (LDL-C) in men and pre- and post-menopausal women while PSY effects on plasma triglycerides (TG) are sex related. A significant decrease in plasma TG was observed in men while postmenopausal women experienced an increase in plasma TG concentrations following PSY supplementation. To further explore the mechanisms by which sex and hormonal status influence the effects of PSY on plasma lipids, HMG-CoA reductase, LDL receptor and lipoprotein lipase (LPL) mRNA abundance were measured in mononuclear cells isolated from these subjects. The intervention followed a randomized crossover design in which participants were allocated to either 15 or 0 g (control) of PSY/d for 30 d. Compared to the control period, PSY intake induced a 20% increase in HMG-CoA reductase mRNA abundance (P < 0.05) while no significant changes in LDL receptor mRNA abundance were observed. In contrast, LPL mRNA abundance was 24% higher in men and 23% lower in postmenopausal women (P < 0.05) when comparing PSY with the control period. These results suggest that the LDL-C lowering induced by PSY was related to changes in HMG-CoA reductase gene expression in monocytes while the expression of LPL in this system was affected by sex and hormonal status.
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Affiliation(s)
- Sonia Vega-López
- Department of Nutritional Sciences, University of Connecticut, Storrs 06269, USA
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38
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Roy S, Freake HC, Fernandez ML. Gender and hormonal status affect the regulation of hepatic cholesterol 7alpha-hydroxylase activity and mRNA abundance by dietary soluble fiber in the guinea pig. Atherosclerosis 2002; 163:29-37. [PMID: 12048119 DOI: 10.1016/s0021-9150(01)00749-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Dietary soluble fiber (SF) consistently lowers plasma LDL cholesterol (LDL-C) concentrations, however, secondary mechanisms governing this reduction are not completely defined. Moreover, these mechanisms appear to differ with gender. Male, female and ovariectomized (to mimic menopause) guinea pigs were used to assess effects of gender, hormonal status and SF on activity and expression of hepatic cholesterol 7alpha-hydroxylase (CYP7). Diets were identical except for fiber source (control 10% cellulose, SF 5% psyllium/5% pectin). SF intake resulted in 44% lower plasma total cholesterol, 51% lower plasma LDL-C and 22% lower plasma triacylglycerol (TAG) concentrations. However, ovariectomized guinea pigs fed either the control or SF diets, had the highest plasma LDL-C and TAG levels (P<0.01). SF altered hepatic cholesterol metabolism by effectively reducing hepatic free cholesterol, TAG and microsomal free cholesterol, while activity of CYP7, the rate-limiting enzyme of cholesterol catabolism, was up-regulated. Hepatic CYP7 mRNA abundance paralleled the increase in enzyme activity. Ovariectomized guinea pigs had lowest activity and expression of hepatic CYP7 even after intervention with SF. These results suggest that induction of hepatic CYP7 activity may account, in large part, for the hypocholesterolemic effect of SF. Gender and hormonal status influence metabolic responses to dietary SF with estrogen deprivation leading to the most detrimental lipid profile.
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Affiliation(s)
- Suheeta Roy
- Department of Nutritional Sciences, University of Connecticut, 3624 Horsebarn Road Extension, U-17, Storrs, CT 06269, USA
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39
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Ramjiganesh T, Roy S, Freake HC, McIntyre JC, Fernandez ML. Corn fiber oil lowers plasma cholesterol by altering hepatic cholesterol metabolism and up-regulating LDL receptors in guinea pigs. J Nutr 2002; 132:335-40. [PMID: 11880551 DOI: 10.1093/jn/132.3.335] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
To evaluate some of the mechanisms involved in the hypocholesterolemic effects of corn fiber oil (CFO), male Hartley guinea pigs were fed diets containing increasing doses of CFO [0 (control), 5, 10 or 15 g/100 g]. Total fat was adjusted to 15 g/100 g in all diets with regular corn oil. Diets contained 0.25 g/100 g cholesterol. A positive control group (LC) with low dietary cholesterol (0.04 g/100 g) was also included. Plasma LDL cholesterol concentrations were 32, 55 and 57% (P < 0.0005) lower with increasing doses of CFO. Compared with controls, intake of CFO resulted in 27-32% lower hepatic microsomal cholesterol (P < 0.0001), the regulatory pool of LDL receptor (LDL-R) expression. CFO intake resulted in favorable plasma and hepatic cholesterol concentrations, similar to those in guinea pigs fed the LC diet. Hepatic cholesterol 7alpha-hydroxylase (CYP7) activity was approximately 88% higher in guinea pigs fed the two higher dosages of CFO (P < 0.05). In parallel, CYP7 mRNA abundance was approximately 88% higher in guinea pigs fed all three CFO diets. CFO treatment also induced hepatic LDLR mRNA by 66-150% with significant differences at the highest CFO dose. These results suggest that CFO, as a result of decreased bile acid absorption, increased mRNA abundance and activity of CYP7. Because hepatic cholesterol is the substrate for CYP7, a lowering of cholesterol concentrations in the total and microsomal pools was observed. As a response to the depleted microsomal free cholesterol pool, the LDL receptor was up-regulated, drawing more cholesterol from plasma, thus leading to the observed decrease in plasma LDL cholesterol concentrations.
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MESH Headings
- Animals
- Base Sequence
- Cholesterol/blood
- Cholesterol/metabolism
- Cholesterol 7-alpha-Hydroxylase/genetics
- Cholesterol 7-alpha-Hydroxylase/metabolism
- Cholesterol, Dietary/administration & dosage
- Cholesterol, LDL/blood
- Corn Oil/pharmacology
- DNA, Complementary/chemistry
- Dietary Fats, Unsaturated/pharmacology
- Guinea Pigs
- Humans
- Liver/drug effects
- Liver/metabolism
- Microsomes, Liver/drug effects
- Microsomes, Liver/metabolism
- Molecular Sequence Data
- RNA, Messenger/analysis
- Rats
- Receptors, LDL/drug effects
- Receptors, LDL/genetics
- Receptors, LDL/metabolism
- Sequence Homology
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Abstract
The rat acetyl-CoA carboxylase (ACC) alpha gene is transcribed from two promoters, denoted PI and PII, that direct regulated expression in a tissue-specific manner. Induction of ACC, the rate-controlling enzyme of fatty acid biosynthesis, occurs in the liver in response to feeding of a high carbohydrate, low fat diet, conditions that favor enhanced lipogenesis. This induction is mainly due to increases in PI promoter activity. We have used primary cultured hepatocytes from the rat to investigate glucose regulation of ACC expression. Glucose and insulin synergistically activated expression of ACC mRNAs transcribed from the PI promoter with little or no effect on PII mRNAs. Glucose treatment stimulated PI promoter activity in transfection assays and a glucose-regulated element was identified (-126/-102), homologous to those previously described in other responsive genes, including l-type pyruvate kinase, S(14) and fatty acid synthase. Mutation of this element eliminated the response to glucose. This region of the ACC PI promoter was able to bind a liver nuclear factor designated ChoRF that interacts with other conserved glucose-regulated elements. This ACC PI element is also capable of conferring a strong response to glucose when linked to a heterologous promoter. We conclude that induction of ACC gene expression under lipogenic conditions in hepatocytes is mediated in part by the activation of a glucose-regulated transcription factor, ChoRF, which stimulates transcription from the PI promoter. Similar mechanisms operate on related genes permitting the coordinate induction of the lipogenic pathway.
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Affiliation(s)
- B L O'Callaghan
- Department of Biochemistry, Molecular Biology & Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA
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41
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Abstract
Both thyroid hormone (triiodo-L-thyronine, T3) and zinc play important roles in growth and development. The T3 receptor is thought to require zinc to adopt its biologically active conformation. Some of the effects of zinc deficiency, therefore, may be due to loss of zinc from the T3 receptor and impairment of T3 action. This possibility was investigated in growing rats by examining the effects of hypothyroidism and hyperthyroidism in zinc-deficient, pair-fed and control rats. Measurement of serum zinc and T3 confirmed the efficacy of the treatments. Zinc deficiency and hypothyroidism resulted in lower food intake and growth failure, but no interaction was observed between the two treatments. Individual tissue weights were influenced by thyroid status as expected, regardless of zinc status. Both dietary and hormonal treatments influenced serum insulin-like growth factor (IGF)-I in an interactive manner. IGF-I was reduced to a greater extent in zinc-deficient than in pair-fed rats compared with controls. Both hypothyroidism and hyperthyroidism reduced serum IGF-I, and a greater reduction due to hyperthyroidism was apparent in zinc-deficient rats. IGF binding proteins were also influenced by diet and thyroid status. The hepatic expression of mRNA S14 was assessed as a direct index of the nuclear action of T3, but its response was not influenced by dietary treatment. Although confirming the role of both T3 and zinc in the regulation of growth and the somatotrophic axis, the growth failure of zinc deficiency does not appear to be due to impaired T3 function.
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Affiliation(s)
- H C Freake
- Department of Nutritional Sciences, University of Connecticut, Storrs, Connecticut 06269-4017, USA.
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42
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Abstract
In the last twenty years, powerful new molecular techniques were introduced that made it possible to advance knowledge in human biology using a reductionist approach. Now, the need for scientists to deal with complexity should drive a movement toward an integrationist approach to science. We propose that nutritional science is one of the best reservoirs for this approach. The American Society for Nutritional Sciences can play an important role by developing and delivering a cogent message that convinces the scientific establishment that nutrition fills this valuable niche. The society must develop a comprehensive strategy to develop our image as the reservoir for life sciences integration. Our efforts can start with our national meeting and publications, with the research initiatives for which we advocate, with our graduate training programs and with the public relations image we project for ourselves. Defining the image and future directions of nutrition as the discipline that can integrate scientific knowledge from the cell and molecule to the whole body and beyond to populations can be the most important task that our society undertakes. If we do not effectively meet this challenge, a golden opportunity will pass to others and nutritional scientists will be left to follow them.
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Affiliation(s)
- S H Zeisel
- Long Range Planning Committee, American Society for Nutritional Sciences.
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43
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Sciaudone MP, Chattopadhyay S, Freake HC. Chelation of zinc amplifies induction of growth hormone mRNA levels in cultured rat pituitary tumor cells. J Nutr 2000; 130:158-63. [PMID: 10720163 DOI: 10.1093/jn/130.2.158] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Zinc is thought to be an integral part of nuclear receptor proteins, stabilizing them in a conformation required for binding to target genes. However, we have recently shown that restriction of zinc availability with a chelator (diethylenetriaminepenta-acetic acid, DTPA) enhances, rather than inhibits, the ability of thyroid hormone to induce growth hormone mRNA expression in GH3 rat pituitary tumor cells. In this report, we have extended these observations by showing that a prolonged (48 h) exposure to DTPA is required to see these effects. The induction by DTPA can be reversed by subsequent addition of zinc, but again, this reversal is slow. A second chelator, EDTA, can also induce growth hormone gene expression in the presence of thyroid hormone, though it is less potent than DTPA. Other agents which act via the nuclear receptor pathway, all-trans and 9-cis retinoic acid, also induce expression of growth hormone mRNA. Addition of DTPA amplifies these effects in a zinc-dependent manner. Thus chelation of zinc potentiates the action of ligands acting via nuclear receptors on growth hormone gene expression. The delayed nature of the response suggests an indirect effect.
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Affiliation(s)
- M P Sciaudone
- Department of Nutritional Sciences, University of Connecticut, Storrs 06269-4017, USA
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44
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Conde K, Roy S, Freake HC, Newton RS, Fernandez ML. Atorvastatin and simvastatin have distinct effects on hydroxy methylglutaryl-CoA reductase activity and mRNA abundance in the guinea pig. Lipids 1999; 34:1327-32. [PMID: 10652993 DOI: 10.1007/s11745-999-0485-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The effects of atorvastatin and simvastatin on hydroxy methylglutaryl (HMG)-CoA reductase activity and mRNA abundance were studied in guinea pigs randomized to three groups: untreated animals and those treated with 20 mg/kg of atorvastatin or simvastatin. Guinea pigs were fasted for 0, 6, 12, or 18 h in an attempt to remove the drug from their systems. Reductase activity and mRNA levels were analyzed after each time point. Reductase inhibitor treatment resulted in 50-62% lower cholesterol concentrations compared to untreated guinea pigs (P < 0.0001), while plasma triacylglycerol (TAG) concentrations did not differ among groups. Plasma cholesterol and TAG were 50-70% lower after 18 h fasting in the three groups (P < 0.001). In the nonfasting state, simvastatin and atorvastatin treatment did not affect HMG-CoA reductase activity compared with untreated animals. However, after 6 h of fasting, simvastatin-treated guinea pigs had higher HMG-CoA reductase activity than untreated animals (P < 0.01), suggesting that the drug had been removed from the enzyme. In contrast, atorvastatin-treated guinea pigs maintained low enzyme activity even after 18 h of fasting. Further, HMG-CoA reductase mRNA abundance was increased by sevenfold after atorvastatin treatment and by twofold after simvastatin treatment (P < 0.01). These results suggest that simvastatin and atorvastatin have different half-lives, which may affect HMG-CoA reductase mRNA levels. The increase in reductase activity by simvastatin during fasting could be related to an effect of this statin in stabilizing the enzyme. In contrast, atorvastatin, possibly due to its longer half-life, prolonged inhibition of HMG-CoA reductase activity and resulted in a greater increase in mRNA synthesis.
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Affiliation(s)
- K Conde
- Department of Nutritional Sciences, University of Connecticut, Storrs 06269, USA
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45
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Abstract
Human obesity may have genetic causes, but determining the specific genes involved has been difficult. The peroxisome proliferator-activated receptor gamma (PPAR gamma) gene encodes a protein that plays an important role in the differentiation of fat cells. A mutation has been discovered in this gene which leads to a receptor that cannot be inactivated. This mutation, while probably rare, is associated with extreme obesity.
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Affiliation(s)
- H C Freake
- Department of Nutritional Sciences, University of Connecticut, Storrs 06269-4017, USA
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46
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Abstract
The acetyl-CoA carboxylase-alpha gene has two promoters, PI and PII. A variety of mRNA products result from this gene, depending on promoter usage and splicing events. We have investigated thyroid hormone regulation of acetyl-CoA carboxylase-alpha gene expression, using the reverse-transcription polymerase chain reaction with PI- or PII-specific primers. RNA was extracted from a range of tissues taken from hypo-, eu-, or hyperthyroid rats. PII-generated products were found in all tissues examined at similar levels and were not affected by thyroid state. Products derived from PI were also widely found but with more variable levels of expression. PI mRNAs were reduced in hypo- and elevated in hyperthyroid livers. In brown adipose tissue, more PI products were found in hypothyroid animals. Thus, thyroid hormone regulates the activity of the acetyl-CoA carboxylase PI promoter to influence fatty acid synthesis in a tissue-specific manner.
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Affiliation(s)
- C Huang
- Department of Nutritional Sciences, University of Connecticut, Storrs 06269-4017, USA
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47
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Abstract
Uncoupling protein, originally described in the inner mitochondrial membrane of brown adipose tissue, permits the oxidation of fuels without the generation of adenosine triphosphate (ATP). Closely related proteins have now been found in many other tissues and shown to be regulated by thyroid hormones and dietary factors. These uncoupling proteins may play a significant role in energy expenditure, with implications for the development of human obesity.
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Affiliation(s)
- H C Freake
- Department of Nutritional Sciences, University of Connecticut, Storrs 06269-4017, USA
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48
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Abstract
The effects of restriction and addition of zinc on thyroid hormone responsiveness of the growth hormone gene were investigated in GH3, rat pituitary tumor cells. Addition of diethylenetriaminepenta-acetic acid (DTPA), a membrane-impermeable chelator, resulted in up to 10-fold increases in GH mRNA in the presence of 10 nM T3, with half-maximal induction at 50 microM DTPA. Only minor effects were seen in the absence of T3. Addition of zinc inhibited the stimulatory effect of DTPA in a dose-dependent manner. Equimolar concentrations of other divalent cations could not substitute for zinc, though inhibitions of the DTPA effect were observed at higher concentrations. In the absence of DTPA, exogenous zinc (100 microM) inhibited T3-induced GH mRNA by approximately 33%. Addition of DTPA or zinc did not affect T3 binding to its nuclear receptor. DTPA also enhanced the stimulatory effect of dexamethasone on GH mRNA. The results demonstrate that restricted zinc availability positively affects T3 induction of the GH gene in GH3 cells.
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Affiliation(s)
- S Chattopadhyay
- Department of Nutritional Sciences, University of Connecticut, Storrs 06269-4017, USA
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49
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Abstract
The acetyl-CoA carboxylase gene contains two promoters, PI and PII which generate multiple mRNA forms. We have used the reverse transcription-polymerase chain reaction to investigate tissue specific promoter usage in rats either fed a standard chow diet, starved for 48 h, or starved and then refed a high carbohydrate, low fat diet. Expression of PII-generated mRNAs was seen in all tissues examined and was not dramatically changed by food removal or refeeding. PI-generated mRNAs were expressed at variable levels in a narrower range of tissues and were regulated by these dietary manipulations. Thus only the PI promoter is responsive to diet and the ability of a tissue to use this promoter determines whether it can alter fatty acid synthesis in response to nutritional challenges.
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Affiliation(s)
- T S Kim
- Department of Nutritional Sciences, University of Connecticut, Storrs 06269-4017, USA
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50
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Abstract
We have previously shown that the effects of a high carbohydrate, fat-free diet and 24-h starvation on fatty acid synthesis in rats are tissue specific. In the present study we examine the tissue-specific pretranslational effects of high carbohydrate feeding, starvation and refeeding a high carbohydrate diet after starvation on the lipogenic pathway by measuring the levels of mRNA encoding acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS) using Northern analysis. Additionally, we measured mRNA S14, a sequence tightly associated with lipogenesis. In rats fed the high carbohydrate diet, hepatic levels of the three mRNA were 3-5 fold higher than in controls. The level of S14 mRNA was doubled in epididymal fat, but other effects of this diet in adipose tissues were not significant. Expression in kidney, heart, lung and brain was not altered. Starvation significantly reduced the level of these mRNA in all tissues examined except brain. In liver, refeeding the high carbohydrate diet induced the expression of ACC, FAS and S14 mRNA 20-30 fold compared with the values found in 48-h starved animals. Hyperinduction of ACC and FAS, but not S14 mRNA expression was also observed in adipose tissues. The tissue-specific nature of these effects is consistent with previous measurements of fatty acid synthesis and confirm that this regulation occurs at the pretranslational level.
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Affiliation(s)
- T S Kim
- Department of Nutritional Sciences, University of Connecticut, Storrs, 06269-4017, USA
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