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Fedders R, Muenzner M, Weber P, Sommerfeld M, Knauer M, Kedziora S, Kast N, Heidenreich S, Raila J, Weger S, Henze A, Schupp M. Liver-secreted RBP4 does not impair glucose homeostasis in mice. J Biol Chem 2018; 293:15269-15276. [PMID: 30126844 DOI: 10.1074/jbc.ra118.004294] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Indexed: 01/07/2023] Open
Abstract
Retinol-binding protein 4 (RBP4) is the major transport protein for retinol in blood. Recent evidence from genetic mouse models shows that circulating RBP4 derives exclusively from hepatocytes. Because RBP4 is elevated in obesity and associates with the development of glucose intolerance and insulin resistance, we tested whether a liver-specific overexpression of RBP4 in mice impairs glucose homeostasis. We used adeno-associated viruses (AAV) that contain a highly liver-specific promoter to drive expression of murine RBP4 in livers of adult mice. The resulting increase in serum RBP4 levels in these mice was comparable with elevated levels that were reported in obesity. Surprisingly, we found that increasing circulating RBP4 had no effect on glucose homeostasis. Also during a high-fat diet challenge, elevated levels of RBP4 in the circulation failed to aggravate the worsening of systemic parameters of glucose and energy homeostasis. These findings show that liver-secreted RBP4 does not impair glucose homeostasis. We conclude that a modest increase of its circulating levels in mice, as observed in the obese, insulin-resistant state, is unlikely to be a causative factor for impaired glucose homeostasis.
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Affiliation(s)
- Ronja Fedders
- From the Charité-Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Pharmacology, 10115 Berlin
| | - Matthias Muenzner
- From the Charité-Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Pharmacology, 10115 Berlin
| | - Pamela Weber
- From the Charité-Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Pharmacology, 10115 Berlin
| | - Manuela Sommerfeld
- From the Charité-Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Pharmacology, 10115 Berlin
| | - Miriam Knauer
- From the Charité-Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Pharmacology, 10115 Berlin
| | - Sarah Kedziora
- From the Charité-Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Pharmacology, 10115 Berlin
| | - Naomi Kast
- From the Charité-Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Pharmacology, 10115 Berlin
| | - Steffi Heidenreich
- From the Charité-Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Pharmacology, 10115 Berlin
| | - Jens Raila
- the Department of Physiology and Pathophysiology, Institute of Nutritional Science, University of Potsdam, 14558 Nuthetal, and
| | - Stefan Weger
- the Charité-Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Virology, Campus Benjamin Franklin, 12203 Berlin, Germany
| | - Andrea Henze
- the Department of Physiology and Pathophysiology, Institute of Nutritional Science, University of Potsdam, 14558 Nuthetal, and
| | - Michael Schupp
- From the Charité-Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Pharmacology, 10115 Berlin,
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Rodriguez-Concepcion M, Avalos J, Bonet ML, Boronat A, Gomez-Gomez L, Hornero-Mendez D, Limon MC, Meléndez-Martínez AJ, Olmedilla-Alonso B, Palou A, Ribot J, Rodrigo MJ, Zacarias L, Zhu C. A global perspective on carotenoids: Metabolism, biotechnology, and benefits for nutrition and health. Prog Lipid Res 2018; 70:62-93. [PMID: 29679619 DOI: 10.1016/j.plipres.2018.04.004] [Citation(s) in RCA: 472] [Impact Index Per Article: 78.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2018] [Revised: 04/16/2018] [Accepted: 04/18/2018] [Indexed: 12/22/2022]
Abstract
Carotenoids are lipophilic isoprenoid compounds synthesized by all photosynthetic organisms and some non-photosynthetic prokaryotes and fungi. With some notable exceptions, animals (including humans) do not produce carotenoids de novo but take them in their diets. In photosynthetic systems carotenoids are essential for photoprotection against excess light and contribute to light harvesting, but perhaps they are best known for their properties as natural pigments in the yellow to red range. Carotenoids can be associated to fatty acids, sugars, proteins, or other compounds that can change their physical and chemical properties and influence their biological roles. Furthermore, oxidative cleavage of carotenoids produces smaller molecules such as apocarotenoids, some of which are important pigments and volatile (aroma) compounds. Enzymatic breakage of carotenoids can also produce biologically active molecules in both plants (hormones, retrograde signals) and animals (retinoids). Both carotenoids and their enzymatic cleavage products are associated with other processes positively impacting human health. Carotenoids are widely used in the industry as food ingredients, feed additives, and supplements. This review, contributed by scientists of complementary disciplines related to carotenoid research, covers recent advances and provides a perspective on future directions on the subjects of carotenoid metabolism, biotechnology, and nutritional and health benefits.
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Affiliation(s)
| | - Javier Avalos
- Department of Genetics, Universidad de Sevilla, 41012 Seville, Spain
| | - M Luisa Bonet
- Laboratory of Molecular Biology, Nutrition and Biotechnology, Universitat de les Illes Balears, 07120 Palma de Mallorca, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 07120 Palma de Mallorca, Spain; Institut d'Investigació Sanitària Illes Balears (IdISBa), 07120 Palma de Mallorca, Spain
| | - Albert Boronat
- Centre for Research in Agricultural Genomics (CRAG) CSIC-IRTA-UAB-UB, 08193 Barcelona, Spain; Department of Biochemistry and Molecular Biomedicine, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Lourdes Gomez-Gomez
- Instituto Botánico, Universidad de Castilla-La Mancha, 02071 Albacete, Spain
| | - Damaso Hornero-Mendez
- Department of Food Phytochemistry, Instituto de la Grasa (IG-CSIC), 41013 Seville, Spain
| | - M Carmen Limon
- Department of Genetics, Universidad de Sevilla, 41012 Seville, Spain
| | - Antonio J Meléndez-Martínez
- Food Color & Quality Laboratory, Area of Nutrition & Food Science, Universidad de Sevilla, 41012 Seville, Spain
| | | | - Andreu Palou
- Laboratory of Molecular Biology, Nutrition and Biotechnology, Universitat de les Illes Balears, 07120 Palma de Mallorca, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 07120 Palma de Mallorca, Spain; Institut d'Investigació Sanitària Illes Balears (IdISBa), 07120 Palma de Mallorca, Spain
| | - Joan Ribot
- Laboratory of Molecular Biology, Nutrition and Biotechnology, Universitat de les Illes Balears, 07120 Palma de Mallorca, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 07120 Palma de Mallorca, Spain; Institut d'Investigació Sanitària Illes Balears (IdISBa), 07120 Palma de Mallorca, Spain
| | - Maria J Rodrigo
- Institute of Agrochemistry and Food Technology (IATA-CSIC), 46980 Valencia, Spain
| | - Lorenzo Zacarias
- Institute of Agrochemistry and Food Technology (IATA-CSIC), 46980 Valencia, Spain
| | - Changfu Zhu
- Department of Plant Production and Forestry Science, Universitat de Lleida-Agrotecnio, 25198 Lleida, Spain
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Bonnefond-Ortega M, Goudable J, Chambrier C, Bétry C. L’absorption intestinale des vitamines hydrosolubles et liposolubles en pratique clinique. NUTR CLIN METAB 2018. [DOI: 10.1016/j.nupar.2017.09.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Mateo-Gallego R, Lamiquiz-Moneo I, Perez-Calahorra S, Marco-Benedí V, Bea AM, Baila-Rueda L, Laclaustra M, Peñalvo JL, Civeira F, Cenarro A. Different protein composition of low-calorie diet differently impacts adipokine profile irrespective of weight loss in overweight and obese women. Nutr Metab Cardiovasc Dis 2018; 28:133-142. [PMID: 29329923 DOI: 10.1016/j.numecd.2017.10.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 10/27/2017] [Accepted: 10/30/2017] [Indexed: 12/19/2022]
Abstract
BACKGROUND AND AIMS High-protein (HP) diets have shown benefits in cardiometabolic markers such as insulin or triglycerides but the responsible mechanisms are not known. We aimed to assess the effect of three energy-restricted diets with different protein contents (20%, 27%, and 35%; ∼80% coming from animal source) on plasma adipokine concentration and its association with changes in cardiometabolic markers. METHODS Seventy-six women (BMI 32.8 ± 2.93) were randomized to one of three calorie-reduced diets, with protein, 20%, 27%, or 35%; carbohydrates, 50%, 43%, or 35%; and fat, 30%, for 3 months. Plasma adipokine (leptin, resistin, adiponectin, and retinol-binding protein 4; RBP4) levels were assessed. RESULTS After 3 months, leptin concentration decreased in all groups without differences among them, while resistin levels remained unchanged. Adiponectin concentration heterogeneously changed in all groups (P for trend = 0.165) and resistin concentration did not significantly change. RPB4 significantly decreased by -17.5% (-31.7, -3.22) in 35%-protein diet (P for trend = 0.024 among diets). Triglycerides improved in women following the 35%-protein diet regardless of weight loss; RBP4 variation significantly influenced triglyceride concentration change by 24.9% and 25.9% when comparing 27%- and 35%- with 20%-protein diet, respectively. CONCLUSIONS A 35%-protein diet induced a decrease in RBP4 regardless of weight loss, which was directly associated with triglyceride concentration improvement. These findings suggest that HP diets improve the cardiometabolic profile, at least in part, through changes in adipokine secretion. Whether this beneficial effect of HP diet is due to improvements in hepatic or adipose tissue functionality should be elucidated. CLINICAL TRIAL REGISTRATION The clinical trial has been registered in ClinicalTrials.gov (Identifier: NCT02160496).
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Affiliation(s)
- R Mateo-Gallego
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón (IIS Aragón), Universidad de Zaragoza, CIBERCV, Zaragoza, Spain.
| | - I Lamiquiz-Moneo
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón (IIS Aragón), Universidad de Zaragoza, CIBERCV, Zaragoza, Spain
| | - S Perez-Calahorra
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón (IIS Aragón), Universidad de Zaragoza, CIBERCV, Zaragoza, Spain
| | - V Marco-Benedí
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón (IIS Aragón), Universidad de Zaragoza, CIBERCV, Zaragoza, Spain
| | - A M Bea
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón (IIS Aragón), Universidad de Zaragoza, CIBERCV, Zaragoza, Spain
| | - L Baila-Rueda
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón (IIS Aragón), Universidad de Zaragoza, CIBERCV, Zaragoza, Spain
| | - M Laclaustra
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón (IIS Aragón), Universidad de Zaragoza, CIBERCV, Zaragoza, Spain
| | - J L Peñalvo
- Tufts Friedman School of Nutrition Science & Policy, Boston, MA, USA
| | - F Civeira
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón (IIS Aragón), Universidad de Zaragoza, CIBERCV, Zaragoza, Spain
| | - A Cenarro
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón (IIS Aragón), Universidad de Zaragoza, CIBERCV, Zaragoza, Spain
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The Retinol-Binding Protein Receptor 2 (Rbpr2) Is Required for Photoreceptor Survival and Visual Function in the Zebrafish. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1074:569-576. [PMID: 29721989 DOI: 10.1007/978-3-319-75402-4_69] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Vitamin A/retinol (ROL) and its metabolites (retinoids) play critical roles in eye development and photoreception. Short-term dietary vitamin A deficiency (VAD) manifests clinically as night blindness, while prolonged VAD is known to cause retinal pigment epithelium (RPE) and photoreceptor degeneration. Therefore, sustained uptake of dietary vitamin A, for ocular retinoid production, is essential for photoreceptor health and visual function. The mechanisms influencing the uptake, storage, and supply of dietary vitamin A, for ocular retinoid production, however, are not fully understood. We investigated, in zebrafish, the physiological role of the retinol-binding protein receptor 2 (Rbpr2), for the uptake of dietary ROL, which is necessary for vision. NIH3T3 cells expressing zebrafish Rbpr2 showed plasma membrane localization patterns and were capable of ROL uptake from its bound form. Using whole-mount in situ hybridization, Rbpr2 was found to be expressed exclusively in the liver, intestine, and pancreas, of staged zebrafish larvae. At 5.5 days post fertilization, TALEN-generated rbpr2 mutants (rbpr2 -/- ) had smaller eyes and shorter OS lengths and showed loss of PNA (cones) and rhodopsin (rods) by immunofluorescence staining. Finally, tests for visual function using optokinetic response (OKR) showed no consistent OKR in rbpr2 -/- larval zebrafish. Our analysis, therefore, suggests that Rbpr2 is capable of ROL uptake and loss of this membrane receptor in zebrafish results in photoreceptor defects that adversely affect visual function.
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56
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Hodges JK, Tan L, Green MH, Ross AC. Vitamin A and retinoic acid combined have a more potent effect compared to vitamin A alone on the uptake of retinol into extrahepatic tissues of neonatal rats raised under vitamin A-marginal conditions. Curr Dev Nutr 2017; 1:cdn.116.000265. [PMID: 29377015 PMCID: PMC5779100 DOI: 10.3945/cdn.116.000265] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 08/07/2017] [Accepted: 09/05/2017] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Vitamin A (VA, retinol) supplementation is widely used to reduce child mortality in low-income countries. However, existing research suggests that supplementation with VA alone may not be optimal for infants. OBJECTIVE We compared the effect of VA vs. VA combined with retinoic acid (VARA) on retinol uptake and turnover in organs of neonatal rats raised under VA-marginal conditions. METHODS Secondary analysis was conducted on data obtained from two prior kinetic studies of Sprague-Dawley neonatal rats nursed by mothers fed a VA-marginal diet (0.35 mg retinol equivalents/kg diet). On postnatal d 4, pups had been treated with a single dose of VA (6 μg/g; n = 52; VA study), VA + 10% retinoic acid (6 μg/g; n = 42; VARA study) or placebo (canola oil; n = 94; both studies), all containing ~2 μCi of [3H]retinol as the tracer for VA. Total retinol concentrations and tracer levels had been measured in plasma and tissues from 1 h to 14 d after dosing. Control group data from both studies were merged prior to analysis. Kinetic parameters were re-estimated and compared statistically. RESULTS VARA supplementation administered to neonatal rats within a few days after birth resulted in a lower turnover of retinol in the lungs, kidneys, and carcass and less frequent recycling of retinol between plasma and organs (100 vs. 288 times in VARA- vs. VA-treated group). Although the VA supplementation resulted in a higher concentration of retinol in the liver, VARA supplementation led to a higher uptake of postprandial retinyl esters into the lungs, intestines, and carcass. CONCLUSIONS Given the relatively higher retinol uptake into several extrahepatic organs of neonates dosed orally with VARA, this form of supplementation may serve as a targeted treatment of low VA levels in the extrahepatic organs that continue to develop postnatally.
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Affiliation(s)
- Joanna K Hodges
- Department of Nutritional Sciences, 204 Chandlee Laboratory The Pennsylvania State University, University Park, PA
| | - Libo Tan
- Department of Nutritional Sciences, 204 Chandlee Laboratory The Pennsylvania State University, University Park, PA
| | - Michael H Green
- Department of Nutritional Sciences, 204 Chandlee Laboratory The Pennsylvania State University, University Park, PA
| | - A Catharine Ross
- Department of Nutritional Sciences, 204 Chandlee Laboratory The Pennsylvania State University, University Park, PA
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Shi Y, Obert E, Rahman B, Rohrer B, Lobo GP. The Retinol Binding Protein Receptor 2 (Rbpr2) is required for Photoreceptor Outer Segment Morphogenesis and Visual Function in Zebrafish. Sci Rep 2017; 7:16207. [PMID: 29176573 PMCID: PMC5701214 DOI: 10.1038/s41598-017-16498-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 11/13/2017] [Indexed: 11/28/2022] Open
Abstract
Vitamin A (all-trans retinol) plays critical roles in mammalian development and vision. Since vitamin A is food-derived, tissue-specific uptake and storage mechanism are needed. In the eye, uptake of RBP4-retinol is mediated by the receptor Stra6, whereas the receptor mediating RBP4 binding and retinol transport into the liver has just recently been discovered. Here we examined the role of zebrafish retinol binding protein receptor 2 (Rbpr2) for RBP4-retinol uptake in developing embryos, using eye development and vision as sensitive readouts. In cultured cells, Rbpr2 localized to membranes and promoted RBP4-retinol uptake. In larvae, Rbpr2 expression was detected in developing intestinal enterocytes and liver hepatocytes. Two rbpr2 mutant zebrafish lines, each resulting in Rbpr2 deficiency, exhibit a small eye defect, and systemic malformations including hydrocephaly and cardiac edema, phenotypes associated with vitamin A deficiency. In the retina, Rbpr2 loss resulted in shorter photoreceptor outer segments, mislocalization and decrease in visual pigments, decreased expression of retinoic acid-responsive genes and photoreceptor cell loss, overall leading to a reduction of visual function. Together, these results demonstrate that Rbpr2-mediated RBP4-retinol uptake in developing liver and intestine is necessary to provide sufficient substrate for ocular retinoid production required for photoreceptor cell maintenance and visual function.
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Affiliation(s)
- Yi Shi
- Department of Medicine, Medical University of South Carolina, Charleston, SC, 29425, USA.,Tianjin Medical University Eye Hospital, Tianjin, 300384, China
| | - Elisabeth Obert
- Department of Ophthalmology, Medical University of South Carolina, Charleston, SC, 29425, USA
| | - Bushra Rahman
- Department of Medicine, Medical University of South Carolina, Charleston, SC, 29425, USA
| | - Bärbel Rohrer
- Department of Ophthalmology, Medical University of South Carolina, Charleston, SC, 29425, USA.,Ralph H. Johnson VA Medical Center, Division of Research, Charleston, SC, 2940, USA
| | - Glenn P Lobo
- Department of Medicine, Medical University of South Carolina, Charleston, SC, 29425, USA. .,Department of Ophthalmology, Medical University of South Carolina, Charleston, SC, 29425, USA.
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Maguire M, Larsen MC, Foong YH, Tanumihardjo S, Jefcoate CR. Cyp1b1 deletion and retinol deficiency coordinately suppress mouse liver lipogenic genes and hepcidin expression during post-natal development. Mol Cell Endocrinol 2017; 454:50-68. [PMID: 28583802 PMCID: PMC5985816 DOI: 10.1016/j.mce.2017.05.037] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 05/30/2017] [Accepted: 05/30/2017] [Indexed: 02/06/2023]
Abstract
UNLABELLED Cyp1b1 deletion and gestational vitamin A deficiency (GVAD) redirect adult liver gene expression. A matched sufficient pre- and post-natal diet, which has high carbohydrate and normal iron content (LF12), increased inflammatory gene expression markers in adult livers that were suppressed by GVAD and Cyp1b1 deletion. At birth on the LF12 diet, Cyp1b1 deletion and GVAD each suppress liver expression of the iron suppressor, hepcidin (Hepc), while increasing stellate cell activation markers and suppressing post-natal increases in lipogenesis. Hepc was less suppressed in Cyp1b1-/- pups with a standard breeder diet, but was restored by iron supplementation of the LF12 diet. CONCLUSIONS The LF12 diet delivered low post-natal iron and attenuated Hepc. Hepc decreases in Cyp1b1-/- and GVAD mice resulted in stellate activation and lipogenesis suppression. Endothelial BMP6, a Hepc stimulant, is a potential coordinator and Cyp1b1 target. These neonatal changes in Cyp1b1-/- mice link to diminished adult obesity and liver inflammation.
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Affiliation(s)
- Meghan Maguire
- Endocrinology and Reproductive Physiology Program, University of Wisconsin-Madison, Madison, WI 53705, United States; Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI 53705, United States
| | - Michele Campaigne Larsen
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI 53705, United States
| | - Yee Hoon Foong
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI 53705, United States
| | - Sherry Tanumihardjo
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, WI 53705, United States
| | - Colin R Jefcoate
- Endocrinology and Reproductive Physiology Program, University of Wisconsin-Madison, Madison, WI 53705, United States; Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI 53705, United States.
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Toriyabe N, Sakurai Y, Kato A, Yamamoto S, Tange K, Nakai Y, Akita H, Harahsima H. The Delivery of Small Interfering RNA to Hepatic Stellate Cells Using a Lipid Nanoparticle Composed of a Vitamin A-Scaffold Lipid-Like Material. J Pharm Sci 2017; 106:2046-2052. [PMID: 28456722 DOI: 10.1016/j.xphs.2017.04.042] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Revised: 02/23/2017] [Accepted: 04/19/2017] [Indexed: 01/22/2023]
Abstract
Hepatic stellate cells (HSCs) are responsible for hepatic fibrosis and liver cirrhosis via their ability to produce extracellular matrices such as collagens and elastin. However, a strategy for delivering cargoes to HSCs has not been established yet. We herein report on attempts to deliver small interfering RNA (siRNA) to HSCs using several types of SS-cleavable proton-activated lipid-like materials (ssPalms) that contained myristic acid (ssPalmM) or hydrophobic vitamin A (ssPalmA) and E (ssPalmE) as hydrophobic scaffolds. We initially verified that hepatic fibrosis could induce the treatment with tetrachloromethane in terms of collagen fibrils and the expression of marker genes, type I collagen α-1, transforming growth factor β, heat shock protein 47, and α-smooth muscle actin. The siRNA silencing efficiency of the 3 LNPs was then compared using fibrosis-induced mice. Of the materials tested, LNPssPalmA showed the highest efficiency, with an effective (ED)50 of approximately 0.25 mg siRNA/kg. The LNPssPalmA showed a significant inhibitory effect on collagen production at a dose of 3.0 mg siRNA/kg with no evidence of any severe adverse effects. In conclusion, LNPssPalmA holds considerable potential for use in the treatment of HSCs-mediated diseases.
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Affiliation(s)
- Naoyuki Toriyabe
- Laboratory for Molecular Design of Pharmaceutics, Faculty of Pharmaceutical Sciences, Hokkaido University, Kita-12, Nishi-6, Kita-ku, Sapporo 060-0812, Japan
| | - Yu Sakurai
- Laboratory for Molecular Design of Pharmaceutics, Faculty of Pharmaceutical Sciences, Hokkaido University, Kita-12, Nishi-6, Kita-ku, Sapporo 060-0812, Japan
| | - Akari Kato
- Laboratory for Molecular Design of Pharmaceutics, Faculty of Pharmaceutical Sciences, Hokkaido University, Kita-12, Nishi-6, Kita-ku, Sapporo 060-0812, Japan
| | - Shoshiro Yamamoto
- Laboratory for Molecular Design of Pharmaceutics, Faculty of Pharmaceutical Sciences, Hokkaido University, Kita-12, Nishi-6, Kita-ku, Sapporo 060-0812, Japan
| | - Kota Tange
- NOF Corporation, 3-3 Chidori-cho, Kawasaki-ku, Kawasaki, Kanagawa 210-0865, Japan
| | - Yuta Nakai
- NOF Corporation, 3-3 Chidori-cho, Kawasaki-ku, Kawasaki, Kanagawa 210-0865, Japan
| | - Hidetaka Akita
- Laboratory of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1, Inohana, Chuo-ku, Chiba City, Chiba 260-8675, Japan
| | - Hideyoshi Harahsima
- Laboratory for Molecular Design of Pharmaceutics, Faculty of Pharmaceutical Sciences, Hokkaido University, Kita-12, Nishi-6, Kita-ku, Sapporo 060-0812, Japan.
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Maguire M, Bushkofsky JR, Larsen MC, Foong YH, Tanumihardjo SA, Jefcoate CR. Diet-dependent retinoid effects on liver gene expression include stellate and inflammation markers and parallel effects of the nuclear repressor Shp. J Nutr Biochem 2017; 47:63-74. [PMID: 28570941 DOI: 10.1016/j.jnutbio.2017.04.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 03/24/2017] [Accepted: 04/12/2017] [Indexed: 02/06/2023]
Abstract
For mice, a maternal vitamin A (VA)-deficient diet initiated from midgestation (GVAD) produces serum retinol deficiency in mature offspring. We hypothesize that the effects of GVAD arise from preweaning developmental changes. We compare the effect of this GVAD protocol in combination with a postweaning high-fat diet (HFD) or high-carbohydrate diet (LF12). Each is compared to an equivalent VA-sufficient combination. GVAD extensively decreased serum retinol and liver retinol, retinyl esters, and retinoid homeostasis genes (Lrat, Cyp26b1 and Cyp26a1). These suppressions were each more effective with LF12 than with HFD. Postweaning initiation of VA deficiency with LF12 depleted liver retinoids, but serum retinol was unaffected. Liver retinoid depletion, therefore, precedes serum attenuation. Maternal LF12 decreased the obesity response to the HFD, which was further decreased by GVAD. LF12 fed to the mother and offspring extensively stimulated genes marking stellate activation (Col1a1, Timp2 and Cyp1b1) and novel inflammation markers (Ly6d, Trem2 and Nupr1). The GVAD with LF12 diet combination suppressed these responses. GVAD in combination with the HFD increased these same clusters. A further set of expression differences on the HFD when compared to a high-carbohydrate diet was prevented when GVAD was combined with HFD. Most of these GVAD gene changes match published effects from deletion of Nr0b2/Shp, a retinoid-responsive, nuclear co-repressor that modulates metabolic homeostasis. The stellate and inflammatory increases seen with the high-carbohydrate LF12 diet may represent postprandial responses. They depend on retinol and Shp, but the regulation reverses with an HFD.
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Affiliation(s)
- Meghan Maguire
- Endocrinology and Reproductive Physiology Program, University of Wisconsin-Madison, Madison, WI 53705; Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI 53705
| | - Justin R Bushkofsky
- Endocrinology and Reproductive Physiology Program, University of Wisconsin-Madison, Madison, WI 53705
| | | | - Yee Hoon Foong
- Endocrinology and Reproductive Physiology Program, University of Wisconsin-Madison, Madison, WI 53705
| | - Sherry A Tanumihardjo
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, WI 53705
| | - Colin R Jefcoate
- Endocrinology and Reproductive Physiology Program, University of Wisconsin-Madison, Madison, WI 53705; Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI 53705.
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61
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Borel P, Desmarchelier C. Genetic Variations Associated with Vitamin A Status and Vitamin A Bioavailability. Nutrients 2017; 9:E246. [PMID: 28282870 PMCID: PMC5372909 DOI: 10.3390/nu9030246] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 02/27/2017] [Accepted: 03/06/2017] [Indexed: 01/11/2023] Open
Abstract
Blood concentration of vitamin A (VA), which is present as different molecules, i.e., mainly retinol and provitamin A carotenoids, plus retinyl esters in the postprandial period after a VA-containing meal, is affected by numerous factors: dietary VA intake, VA absorption efficiency, efficiency of provitamin A carotenoid conversion to VA, VA tissue uptake, etc. Most of these factors are in turn modulated by genetic variations in genes encoding proteins involved in VA metabolism. Genome-wide association studies (GWAS) and candidate gene association studies have identified single nucleotide polymorphisms (SNPs) associated with blood concentrations of retinol and β-carotene, as well as with β-carotene bioavailability. These genetic variations likely explain, at least in part, interindividual variability in VA status and in VA bioavailability. However, much work remains to be done to identify all of the SNPs involved in VA status and bioavailability and to assess the possible involvement of other kinds of genetic variations, e.g., copy number variants and insertions/deletions, in these phenotypes. Yet, the potential usefulness of this area of research is exciting regarding the proposition of more personalized dietary recommendations in VA, particularly in populations at risk of VA deficiency.
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Affiliation(s)
- Patrick Borel
- NORT, Aix-Marseille Université, INRA, INSERM, 13005 Marseille, France.
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62
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Vidailhet M, Rieu D, Feillet F, Bocquet A, Chouraqui JP, Darmaun D, Dupont C, Frelut ML, Girardet JP, Hankard R, Rozé JC, Siméoni U, Turck D, Briend A. Vitamin A in pediatrics: An update from the Nutrition Committee of the French Society of Pediatrics. Arch Pediatr 2017; 24:288-297. [DOI: 10.1016/j.arcped.2016.11.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 11/30/2016] [Indexed: 12/16/2022]
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63
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Chen Y, Clarke OB, Kim J, Stowe S, Kim YK, Assur Z, Cavalier M, Godoy-Ruiz R, von Alpen DC, Manzini C, Blaner WS, Frank J, Quadro L, Weber DJ, Shapiro L, Hendrickson WA, Mancia F. Structure of the STRA6 receptor for retinol uptake. Science 2017; 353:353/6302/aad8266. [PMID: 27563101 DOI: 10.1126/science.aad8266] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Accepted: 06/16/2016] [Indexed: 12/20/2022]
Abstract
Vitamin A homeostasis is critical to normal cellular function. Retinol-binding protein (RBP) is the sole specific carrier in the bloodstream for hydrophobic retinol, the main form in which vitamin A is transported. The integral membrane receptor STRA6 mediates cellular uptake of vitamin A by recognizing RBP-retinol to trigger release and internalization of retinol. We present the structure of zebrafish STRA6 determined to 3.9-angstrom resolution by single-particle cryo-electron microscopy. STRA6 has one intramembrane and nine transmembrane helices in an intricate dimeric assembly. Unexpectedly, calmodulin is bound tightly to STRA6 in a noncanonical arrangement. Residues involved with RBP binding map to an archlike structure that covers a deep lipophilic cleft. This cleft is open to the membrane, suggesting a possible mode for internalization of retinol through direct diffusion into the lipid bilayer.
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Affiliation(s)
- Yunting Chen
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA
| | - Oliver B Clarke
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Jonathan Kim
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA
| | - Sean Stowe
- The Center for Biomolecular Therapeutics and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Youn-Kyung Kim
- Department of Food Science and Rutgers Center for Lipid Research, Rutgers University, New Brunswick, NJ 08901, USA
| | - Zahra Assur
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA
| | - Michael Cavalier
- The Center for Biomolecular Therapeutics and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Raquel Godoy-Ruiz
- The Center for Biomolecular Therapeutics and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Desiree C von Alpen
- Department of Pharmacology and Physiology and Department of Integrative Systems Biology, George Washington University, Washington, DC 20037, USA
| | - Chiara Manzini
- Department of Pharmacology and Physiology and Department of Integrative Systems Biology, George Washington University, Washington, DC 20037, USA
| | - William S Blaner
- Department of Medicine, Columbia University, New York, NY 10032, USA
| | - Joachim Frank
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Loredana Quadro
- Department of Food Science and Rutgers Center for Lipid Research, Rutgers University, New Brunswick, NJ 08901, USA
| | - David J Weber
- The Center for Biomolecular Therapeutics and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Lawrence Shapiro
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Wayne A Hendrickson
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA. Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Filippo Mancia
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA.
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64
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Shannon SR, Moise AR, Trainor PA. New insights and changing paradigms in the regulation of vitamin A metabolism in development. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2017; 6. [PMID: 28207193 DOI: 10.1002/wdev.264] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 11/14/2016] [Accepted: 11/24/2016] [Indexed: 12/17/2022]
Abstract
Vitamin A and its active metabolite retinoic acid are essential for embryonic development and adult homeostasis. Surprisingly, excess or deficiency of vitamin A and retinoic acid can cause similar developmental defects. Therefore, strict feedback and other mechanisms exist to regulate the levels of retinoic acid within a narrow physiological range. The oxidation of vitamin A to retinal has recently been established as a critical nodal point in the synthesis of retinoic acid, and over the past decade, RDH10 and DHRS3 have emerged as the predominant enzymes that regulate this reversible reaction. Together they form a codependent complex that facilitates negative feedback maintenance of retinoic acid levels and thus guard against the effects of dysregulated vitamin A metabolism and retinoic acid synthesis. This review focuses on advances in our understanding of the roles of Rdh10 and Dhrs3 and their impact on development and disease. WIREs Dev Biol 2017, 6:e264. doi: 10.1002/wdev.264 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Stephen R Shannon
- Stowers Institute for Medical Research, Kansas City, MO, USA.,Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS, USA
| | - Alexander R Moise
- Department of Pharmacology and Toxicology, School of Pharmacy, University of Kansas, Lawrence, KS, USA
| | - Paul A Trainor
- Stowers Institute for Medical Research, Kansas City, MO, USA.,Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS, USA
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Hsu CY, Chen CH, Aljuffali IA, Dai YS, Fang JY. Nanovesicle delivery to the liver via retinol binding protein and platelet-derived growth factor receptors: how targeting ligands affect biodistribution. Nanomedicine (Lond) 2017; 12:317-331. [DOI: 10.2217/nnm-2016-0319] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Aim: Nanovesicles (NVs) conjugating ligands can deliver to the specific nidus. We designed a nanosystem targeting the injectable niosomes to liver for examining biodistribution. Methodology: Vitamin A and antiplatelet-derived growth factor receptor antibody were employed as the ligands to be taken by hepatic stellate cells. The biodistribution in rats was visualized by bioimaging. Results: A significant liver accumulation was detected for antibody-embedded NVs at 2 h after dosing. The vitamin A embedded NVs exhibited a delayed targeting to the liver (5 h). The spleen, intestine and kidneys were the nontargeted organs where the vitamin A loaded niosomes largely accumulated. The antibody-loaded NVs could deliver to the spleen, kidneys and lungs. The antibody-loaded nanocarriers increased silibinin uptake to lungs by fourfold than the plain NVs. Conclusion: The results have practical application for better designing of active targeting nanocarriers.
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Affiliation(s)
- Ching-Yun Hsu
- Department of Nutrition & Health Sciences, Chang Gung University of Science & Technology, Kweishan, Taoyuan, Taiwan
- Research Center for Chinese Herbal Medicine & Research Center for Food and Cosmetic Safety, Chang Gung University of Science & Technology, Kweishan, Taoyuan, Taiwan
| | - Chun-Han Chen
- Division of General Surgery, Department of Surgery, Chang Gung Memorial Hospital, Chiayi, Taiwan
| | - Ibrahim A Aljuffali
- Department of Pharmaceutics, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia
| | - You-Shan Dai
- Pharmaceutics Laboratory, Graduate Institute of Natural Products, Chang Gung University, Kweishan, Taoyuan, Taiwan
| | - Jia-You Fang
- Research Center for Chinese Herbal Medicine & Research Center for Food and Cosmetic Safety, Chang Gung University of Science & Technology, Kweishan, Taoyuan, Taiwan
- Pharmaceutics Laboratory, Graduate Institute of Natural Products, Chang Gung University, Kweishan, Taoyuan, Taiwan
- Chinese Herbal Medicine Research Team, Healthy Aging Research Center, Chang Gung University, Kweishan, Taoyuan, Taiwan
- Department of Anesthesiology, Chang Gung Memorial Hospital, Kweishan, Taoyuan, Taiwan
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66
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Saeed A, Hoekstra M, Hoeke MO, Heegsma J, Faber KN. The interrelationship between bile acid and vitamin A homeostasis. Biochim Biophys Acta Mol Cell Biol Lipids 2017; 1862:496-512. [PMID: 28111285 DOI: 10.1016/j.bbalip.2017.01.007] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 01/04/2017] [Accepted: 01/18/2017] [Indexed: 12/12/2022]
Abstract
Vitamin A is a fat-soluble vitamin important for vision, reproduction, embryonic development, cell differentiation, epithelial barrier function and adequate immune responses. Efficient absorption of dietary vitamin A depends on the fat-solubilizing properties of bile acids. Bile acids are synthesized in the liver and maintained in an enterohepatic circulation. The liver is also the main storage site for vitamin A in the mammalian body, where an intimate collaboration between hepatocytes and hepatic stellate cells leads to the accumulation of retinyl esters in large cytoplasmic lipid droplet hepatic stellate cells. Chronic liver diseases are often characterized by disturbed bile acid and vitamin A homeostasis, where bile production is impaired and hepatic stellate cells lose their vitamin A in a transdifferentiation process to myofibroblasts, cells that produce excessive extracellular matrix proteins leading to fibrosis. Chronic liver diseases thus may lead to vitamin A deficiency. Recent data reveal an intricate crosstalk between vitamin A metabolites and bile acids, in part via the Retinoic Acid Receptor (RAR), Retinoid X Receptor (RXR) and the Farnesoid X Receptor (FXR), in maintaining vitamin A and bile acid homeostasis. Here, we provide an overview of the various levels of "communication" between vitamin A metabolites and bile acids and its relevance for the treatment of chronic liver diseases.
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Affiliation(s)
- Ali Saeed
- Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands; Institute of Molecular biology & Bio-technology, Bahauddin Zakariya University, Multan, Pakistan.
| | - Mark Hoekstra
- Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
| | - Martijn Oscar Hoeke
- Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
| | - Janette Heegsma
- Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands; Laboratory Medicine, Center for Liver, Digestive, and Metabolic Diseases, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
| | - Klaas Nico Faber
- Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
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Grumet L, Taschler U, Lass A. Hepatic Retinyl Ester Hydrolases and the Mobilization of Retinyl Ester Stores. Nutrients 2016; 9:nu9010013. [PMID: 28035980 PMCID: PMC5295057 DOI: 10.3390/nu9010013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 12/12/2016] [Accepted: 12/21/2016] [Indexed: 12/26/2022] Open
Abstract
For mammals, vitamin A (retinol and metabolites) is an essential micronutrient that is required for the maintenance of life. Mammals cannot synthesize vitamin A but have to obtain it from their diet. Resorbed dietary vitamin A is stored in large quantities in the form of retinyl esters (REs) in cytosolic lipid droplets of cells to ensure a constant supply of the body. The largest quantities of REs are stored in the liver, comprising around 80% of the body’s total vitamin A content. These hepatic vitamin A stores are known to be mobilized under times of insufficient dietary vitamin A intake but also under pathological conditions such as chronic alcohol consumption and different forms of liver diseases. The mobilization of REs requires the activity of RE hydrolases. It is astounding that despite their physiological significance little is known about their identities as well as about factors or stimuli which lead to their activation and consequently to the mobilization of hepatic RE stores. In this review, we focus on the recent advances for the understanding of hepatic RE hydrolases and discuss pathological conditions which lead to the mobilization of hepatic RE stores.
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Affiliation(s)
- Lukas Grumet
- Institute of Molecular Biosciences, University of Graz, Heinrichstraße 31, 8010 Graz, Austria.
| | - Ulrike Taschler
- Institute of Molecular Biosciences, University of Graz, Heinrichstraße 31, 8010 Graz, Austria.
| | - Achim Lass
- Institute of Molecular Biosciences, University of Graz, Heinrichstraße 31, 8010 Graz, Austria.
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68
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Cottin SC, Gambling L, Hayes HE, Stevens VJ, McArdle HJ. Pregnancy and maternal iron deficiency stimulate hepatic CRBPII expression in rats. J Nutr Biochem 2016; 32:55-63. [DOI: 10.1016/j.jnutbio.2016.02.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 02/26/2016] [Accepted: 02/26/2016] [Indexed: 12/30/2022]
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69
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Kelly M, Widjaja-Adhi MAK, Palczewski G, von Lintig J. Transport of vitamin A across blood-tissue barriers is facilitated by STRA6. FASEB J 2016; 30:2985-95. [PMID: 27189978 DOI: 10.1096/fj.201600446r] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 05/02/2016] [Indexed: 12/31/2022]
Abstract
Vitamin A bound to retinol binding protein 4 (RBP4) constitutes the major transport mode for retinoids in fasting circulation. Emerging evidence suggests that membrane protein, STRA6 (stimulated by retinoic acid 6), is the RBP4 receptor and vitamin A channel; however, the role of STRA6 in vitamin A homeostasis remains to be defined in vivo We subjected Stra6-knockout mice to diets sufficient and insufficient for vitamin A and used heterozygous siblings as controls. We determined vitamin A levels of the eyes, brain, and testis, which highly express Stra6, as well as of tissues with low expression, such as lung and fat. We also studied the consequence of STRA6 deficiency on retinoid-dependent processes in tissues. Furthermore, we examined how STRA6 deficiency affected retinoid homeostasis of the aging mouse. The picture that emerged indicates a critical role for STRA6 in the transport of vitamin A across blood-tissue barriers in the eyes, brain, and testis. Concurrently, fat and lung rely on dietary vitamin A. In testis and brain, Stra6 expression was regulated by vitamin A. In controls, this regulation reduced vitamin A consumption when the dietary supply was limited, sequestering it for the eye. Thus, STRA6 is critical for vitamin A homeostasis and the adaption of this process to the fluctuating supply of the vitamin.-Kelly, M., Widjaja-Adhi, M. A. K., Palczewski, G., von Lintig, J. Transport of vitamin A across blood-tissue barriers is facilitated by STRA6.
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Affiliation(s)
- Mary Kelly
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - M Airanthi K Widjaja-Adhi
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Grzegorz Palczewski
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Johannes von Lintig
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
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70
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di Masi A, Trezza V, Leboffe L, Ascenzi P. Human plasma lipocalins and serum albumin: Plasma alternative carriers? J Control Release 2016; 228:191-205. [PMID: 26951925 DOI: 10.1016/j.jconrel.2016.02.049] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Revised: 02/23/2016] [Accepted: 02/24/2016] [Indexed: 01/14/2023]
Abstract
Lipocalins are an evolutionarily conserved family of proteins that bind and transport a variety of exogenous and endogenous ligands. Lipocalins share a conserved eight anti-parallel β-sheet structure. Among the different lipocalins identified in humans, α-1-acid glycoprotein (AGP), apolipoprotein D (apoD), apolipoprotein M (apoM), α1-microglobulin (α1-m) and retinol-binding protein (RBP) are plasma proteins. In particular, AGP is the most important transporter for basic and neutral drugs, apoD, apoM, and RBP mainly bind endogenous molecules such as progesterone, pregnenolone, bilirubin, sphingosine-1-phosphate, and retinol, while α1-m binds the heme. Human serum albumin (HSA) is a monomeric all-α protein that binds endogenous and exogenous molecules like fatty acids, heme, and acidic drugs. Changes in the plasmatic levels of lipocalins and HSA are responsible for the onset of pathological conditions associated with an altered drug transport and delivery. This, however, does not necessary result in potential adverse effects in patients because many drugs can bind both HSA and lipocalins, and therefore mutual compensatory binding mechanisms can be hypothesized. Here, molecular and clinical aspects of ligand transport by plasma lipocalins and HSA are reviewed, with special attention to their role as alterative carriers in health and disease.
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Affiliation(s)
- Alessandra di Masi
- Dipartimento di Scienze, Università Roma Tre, Viale Marconi 446, I-00146 Roma, Italy; Istituto Nazionale di Biostrutture e Biosistemi, Via delle Medaglie d'Oro 305, I-00136 Roma, Italy.
| | - Viviana Trezza
- Dipartimento di Scienze, Università Roma Tre, Viale Marconi 446, I-00146 Roma, Italy
| | - Loris Leboffe
- Dipartimento di Scienze, Università Roma Tre, Viale Marconi 446, I-00146 Roma, Italy; Istituto Nazionale di Biostrutture e Biosistemi, Via delle Medaglie d'Oro 305, I-00136 Roma, Italy
| | - Paolo Ascenzi
- Istituto Nazionale di Biostrutture e Biosistemi, Via delle Medaglie d'Oro 305, I-00136 Roma, Italy; Laboratorio Interdipartimentale di Microscopia Elettronica, Università Roma Tre, Via della Vasca Navale 79, I-00146 Roma, Italy
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High dietary fat–induced obesity in Wistar rats and type 2 diabetes in nonobese Goto-Kakizaki rats differentially affect retinol binding protein 4 expression and vitamin A metabolism. Nutr Res 2016; 36:262-70. [DOI: 10.1016/j.nutres.2015.11.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 11/23/2015] [Accepted: 11/26/2015] [Indexed: 12/12/2022]
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72
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Schleinitz D. Genetic Determination of Serum Levels of Diabetes-Associated Adipokines. Rev Diabet Stud 2016; 12:277-98. [PMID: 26859657 PMCID: PMC5275755 DOI: 10.1900/rds.2015.12.277] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2015] [Accepted: 10/06/2015] [Indexed: 12/16/2022] Open
Abstract
Adipose tissue secretes an abundance of proteins. Some of these proteins are known as adipokines and adipose-derived hormones which have been linked with metabolic disorders, including type 2 diabetes, and even with cancer. Variance in serum adipokine concentration is often closely associated with an increase (obesity) or decrease (lipodystrophy) in fat tissue mass, and it is affected by age, gender, and localization of the adipose tissue. However, there may be genetic variants which, in consequence, influence the serum concentration of a certain adipokine, and thereby promote metabolic disturbances or, with regard to the "protective" allele, exert beneficial effects. This review focuses on the genetic determination of serum levels of the following adipokines: adiponectin, chemerin, leptin, progranulin, resistin, retinol binding protein 4, vaspin, adipsin, apelin, and omentin. The article reports on the latest findings from genome-wide association studies (GWAS) and candidate gene studies, showing variants located in/nearby the adipokine genes and other (non-receptor) genes. An extra chapter highlights adipokine-receptor variants. Epigenetic studies on adipokines are also addressed.
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Affiliation(s)
- Dorit Schleinitz
- Integrated Research and Treatment Center AdiposityDiseases, University of Leipzig, Liebigstr. 21, 04103 Leipzig, Germany
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73
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Abstract
Cell, animal and human studies dealing with carotenoids and carotenoid derivatives as nutritional regulators of adipose tissue biology with implications for the etiology and management of obesity and obesity-related metabolic diseases are reviewed. Most studied carotenoids in this context are β-carotene, cryptoxanthin, astaxanthin and fucoxanthin, together with β-carotene-derived retinoids and some other apocarotenoids. Studies indicate an impact of these compounds on essential aspects of adipose tissue biology including the control of adipocyte differentiation (adipogenesis), adipocyte metabolism, oxidative stress and the production of adipose tissue-derived regulatory signals and inflammatory mediators. Specific carotenoids and carotenoid derivatives restrain adipogenesis and adipocyte hypertrophy while enhancing fat oxidation and energy dissipation in brown and white adipocytes, and counteract obesity in animal models. Intake, blood levels and adipocyte content of carotenoids are reduced in human obesity. Specifically designed human intervention studies in the field, though still sparse, indicate a beneficial effect of carotenoid supplementation in the accrual of abdominal adiposity. In summary, studies support a role of specific carotenoids and carotenoid derivatives in the prevention of excess adiposity, and suggest that carotenoid requirements may be dependent on body composition.
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Affiliation(s)
- M Luisa Bonet
- Group of Nutrigenomics and Obesity, Laboratory of Molecular Biology, Nutrition and Biotechnology, Universitat de les Illes Balears, Cra. Valldemossa Km 7.5. 07122, Palma de Mallorca, Spain.
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Palma de Mallorca, Spain.
| | - Jose A Canas
- Metabolism and Diabetes, Nemours Children's Clinic, Jacksonville, FL, 32207, USA
| | - Joan Ribot
- Group of Nutrigenomics and Obesity, Laboratory of Molecular Biology, Nutrition and Biotechnology, Universitat de les Illes Balears, Cra. Valldemossa Km 7.5. 07122, Palma de Mallorca, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Palma de Mallorca, Spain
| | - Andreu Palou
- Group of Nutrigenomics and Obesity, Laboratory of Molecular Biology, Nutrition and Biotechnology, Universitat de les Illes Balears, Cra. Valldemossa Km 7.5. 07122, Palma de Mallorca, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Palma de Mallorca, Spain
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Abstract
Retinoic acid (RA) was identified as the biologically active form of vitamin A almost 70 years ago and work on its function and mechanism of action is still of major interest both from a scientific and a clinical perspective. The currently accepted model postulates that RA is produced in two sequential oxidative steps: first, retinol is oxidized reversibly to retinaldehyde, and then retinaldehyde is oxidized irreversibly to RA. Excess RA is inactivated by conversion to hydroxylated derivatives. Much is left to learn, especially about retinoid binding proteins and the trafficking of the hydrophobic retinoid substrates between membrane bound and cytosolic enzymes. Here, background on development of the field and an update on recent advances in our understanding of the enzymatic pathways and mechanisms that control the rate of RA production and degradation are presented with a focus on the many questions that remain unanswered.
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75
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Abstract
Vitamin A, retinol, circulates in blood bound to retinol binding protein (RBP). In some tissues, the retinol-RBP complex (holo-RBP) is recognized by a membrane receptor, termed STRA6, which mediates uptake of retinol into cells. Recent studies have revealed that, in addition to serving as a retinol transporter, STRA6 is a ligand-activated cell surface signaling receptor that, upon binding of holo-RBP activates JAK/STAT signaling, culminating in the induction of STAT target genes. It has further been shown that retinol transport and cell signaling by STRA6 are critically interdependent and that both are coupled to intracellular vitamin A metabolism. The molecular mechanism of action of STRA6 and its associated machinery is beginning to be revealed, but further work is needed to identify and characterize the complete range of genes and associated signaling cascades that are regulated by STRA6 in different tissues. An understanding of STRA6 is clinically relevant, as for example, it has been shown to be hyper- activated in obese animals, leading to insulin resistance. A potential role for STRA6 in other pathologies, including cancer, awaits further investigation.
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Affiliation(s)
- Noa Noy
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH, 44195, USA.
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Zeitz J, Most E, Eder K. Short communication: Effect of conjugated linoleic acid on concentrations of fat-soluble vitamins in milk of lactating ewes. J Dairy Sci 2015; 98:7328-34. [DOI: 10.3168/jds.2014-9218] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 06/19/2015] [Indexed: 12/27/2022]
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77
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Kelly M, von Lintig J. STRA6: role in cellular retinol uptake and efflux. Hepatobiliary Surg Nutr 2015; 4:229-42. [PMID: 26312242 DOI: 10.3978/j.issn.2304-3881.2015.01.12] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 01/13/2015] [Indexed: 12/11/2022]
Abstract
Distribution of vitamin A throughout the body is important to maintain retinoid function in peripheral tissues and to ensure optimal vision. A critical step of this process is the transport of vitamin A across cell membranes. Increasing evidence indicates that this process is mediated by a multidomian membrane protein that is encoded by the stimulated by retinoic acid 6 (STRA6) gene. Biochemical studies revealed that STRA6 is a transmembrane pore which transports vitamin A bidirectionally between extra- and intracellular retinoid binding proteins. Vitamin A accumulation in cells is driven by coupling of transport with vitamin A esterification. Loss-of-function studies in zebrafish and mouse models have unraveled the critical importance of STRA6 for vitamin A homeostasis of peripheral tissues. Impairment in vitamin A transport and uptake homeostasis are associated with diseases including type 2 diabetes and a microphthalmic syndrome known as Matthew Wood Syndrome. This review will discuss the advanced state of knowledge about STRA6's biochemistry, biology and association with disease.
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Affiliation(s)
- Mary Kelly
- Department of Pharmacology, Case School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Johannes von Lintig
- Department of Pharmacology, Case School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
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78
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Effects of dietary vitamin A supplementation or restriction and its timing on retinol and α-tocopherol accumulation and gene expression in heavy pigs. Anim Feed Sci Technol 2015. [DOI: 10.1016/j.anifeedsci.2015.01.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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79
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Breen CJ, Martin DS, Ma H, McQuaid K, O'Kennedy R, Findlay JBC. Production of functional human vitamin A transporter/RBP receptor (STRA6) for structure determination. PLoS One 2015; 10:e0122293. [PMID: 25816144 PMCID: PMC4376794 DOI: 10.1371/journal.pone.0122293] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Accepted: 02/11/2015] [Indexed: 02/06/2023] Open
Abstract
STRA6 is a plasma membrane protein that mediates the transport of vitamin A, or retinol, from plasma retinol binding protein (RBP) into the cell. Mutations in human STRA6 are associated with Matthew-Wood syndrome, which is characterized by severe developmental defects. Despite the obvious importance of this protein to human health, little is known about its structure and mechanism of action. To overcome the difficulties frequently encountered with the production of membrane proteins for structural determination, STRA6 has been expressed in Pichia pastoris as a fusion to green fluorescent protein (GFP), a strategy which has been a critical first step in solving the crystal structures of several membrane proteins. STRA6-GFP was correctly targeted to the cell surface where it bound RBP. Here we report the large-scale expression, purification and characterisation of STRA6-GFP. One litre of culture, corresponding to 175 g cells, yielded about 1.5 mg of pure protein. The interaction between purified STRA6 and its ligand RBP was studied by surface plasmon resonance-based binding analysis. The interaction between STRA6 and RBP was not retinol-dependent and the binding data were consistent with a transient interaction of 1 mole RBP/mole STRA6.
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Affiliation(s)
- Conor J Breen
- Department of Biology, National University of Ireland Maynooth, Maynooth, Co. Kildare, Ireland
| | - Darren S Martin
- Department of Biology, National University of Ireland Maynooth, Maynooth, Co. Kildare, Ireland
| | - Hui Ma
- National Centre for Sensor Research, Biomedical Diagnostics Institute, Dublin City University, Dublin, Ireland
| | - Kate McQuaid
- Department of Biology, National University of Ireland Maynooth, Maynooth, Co. Kildare, Ireland
| | - Richard O'Kennedy
- National Centre for Sensor Research, Biomedical Diagnostics Institute, Dublin City University, Dublin, Ireland
| | - John B C Findlay
- Department of Biology, National University of Ireland Maynooth, Maynooth, Co. Kildare, Ireland
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80
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Laursen KB, Kashyap V, Scandura J, Gudas LJ. An alternative retinoic acid-responsive Stra6 promoter regulated in response to retinol deficiency. J Biol Chem 2015; 290:4356-66. [PMID: 25544292 PMCID: PMC4326842 DOI: 10.1074/jbc.m114.613968] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 12/25/2014] [Indexed: 01/27/2023] Open
Abstract
Cellular uptake of vitamin A (retinol) is essential for many biological functions. The Stra6 protein binds the serum retinol-binding protein, RBP4, and acts in conjunction with the enzyme lecithin:retinol acyltransferase to facilitate retinol uptake in some cell types. We show that in embryonic stem (ES) cells and in some tissues, the Stra6 gene encodes two distinct mRNAs transcribed from two different promoters. Whereas both are all-trans-retinoic acid (RA)-responsive in ES cells, the downstream promoter contains a half-site RA response element (RARE) and drives an ∼ 13-fold, RA-associated increase in luciferase reporter activity. We employed CRISPR-Cas9 genome editing to show that the endogenous RARE is required for RA-induced transcription of both Stra6 isoforms. We further demonstrate that in ES cells, 1) both RARγ and RXRα are present at the Stra6 RARE; 2) RA increases co-activator p300 (KAT3B) binding and histone H3 Lys-27 acetylation at both promoters; 3) RA decreases Suz12 levels and histone H3 Lys-27 trimethylation epigenetic marks at both promoters; and 4) these epigenetic changes are diminished in the absence of RARγ. In the brains of WT mice, both the longer and the shorter Stra6 transcript (Stra6L and Stra6S, respectively) are highly expressed, whereas these transcripts are found only at low levels in RARγ(-/-) mice. In the brains of vitamin A-deficient mice, both Stra6L and Stra6S levels are decreased. In contrast, in the vitamin A-deficient kidneys, the Stra6L levels are greatly increased, whereas Stra6S levels are decreased. Our data show that kidneys respond to retinol deficiency by differential Stra6 promoter usage, which may play a role in the retention of retinol when vitamin A is low.
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Affiliation(s)
| | | | - Joseph Scandura
- the Department of Medicine, Weill Cornell Medical College of Cornell University, New York, New York 10065
| | - Lorraine J Gudas
- From the Pharmacology Department and the Department of Medicine, Weill Cornell Medical College of Cornell University, New York, New York 10065
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81
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Li Y, Wongsiriroj N, Blaner WS. The multifaceted nature of retinoid transport and metabolism. Hepatobiliary Surg Nutr 2014; 3:126-39. [PMID: 25019074 DOI: 10.3978/j.issn.2304-3881.2014.05.04] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Accepted: 05/23/2014] [Indexed: 12/16/2022]
Abstract
Since their discovery over a century ago, retinoids have been the most studied of the fat-soluble vitamins. Unlike most vitamins, retinoids are stored at relatively high concentrations in the body to buffer against nutritional insufficiency. Until recently, it was thought that the sole important retinoid delivery pathway to tissues involved retinol bound to retinol-binding protein (RBP4). More recent findings, however, indicate that retinoids can be delivered to tissues through multiple overlapping delivery pathways, involving chylomicrons, very low density lipoprotein (VLDL) and low density lipoprotein (LDL), retinoic acid bound to albumin, water soluble β-glucuronides of retinol and retinoic acid, and provitamin A carotenoids. This review will focus on explaining this evolving understanding of retinoid metabolism and transport within the body.
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Affiliation(s)
- Yang Li
- 1 Columbia College, Columbia University, New York, NY, USA ; 2 Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, Thailand ; 3 College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Nuttaporn Wongsiriroj
- 1 Columbia College, Columbia University, New York, NY, USA ; 2 Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, Thailand ; 3 College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - William S Blaner
- 1 Columbia College, Columbia University, New York, NY, USA ; 2 Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, Thailand ; 3 College of Physicians and Surgeons, Columbia University, New York, NY, USA
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82
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Abstract
In this issue, Skazik et al. demonstrate that the STRA6 retinol transporter protein regulates the proliferation and differentiation of epidermal keratinocytes. In human organotypic three-dimensional skin and skin reconstitution models, depletion of STRA6 induced hyperproliferation-associated differentiation, resulting in epidermal expansion. This reveals that STRA6 functions as a "gatekeeper" in retinol (vitamin A)-mediated differentiation of human skin.
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83
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Fujita T. Role of retinol binding protein 4 in hepatic steatosis. Hepatology 2014; 59:2422. [PMID: 24115261 DOI: 10.1002/hep.26759] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 08/16/2013] [Indexed: 12/07/2022]
Affiliation(s)
- Tetsuji Fujita
- Department of Surgery, Jikei University School of Medicine, Tokyo, Japan
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84
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Amengual J, Zhang N, Kemerer M, Maeda T, Palczewski K, Von Lintig J. STRA6 is critical for cellular vitamin A uptake and homeostasis. Hum Mol Genet 2014; 23:5402-17. [PMID: 24852372 DOI: 10.1093/hmg/ddu258] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Vitamin A must be adequately distributed within the body to maintain the functions of retinoids in the periphery and chromophore production in the eyes. Blood transport of the lipophilic vitamin is mediated by the retinol-binding protein, RBP4. Biochemical evidence suggests that cellular uptake of vitamin A from RBP4 is facilitated by a membrane receptor. This receptor, identified as the Stimulated by retinoic acid gene 6 (Stra6) gene product, is highly expressed in epithelia that constitute blood-tissue barriers. Here we established a Stra6 knockout mouse model to analyze the metabolic basis of vitamin A homeostasis in peripheral tissues. These mice were viable when bred on diets replete in vitamin A, but evidenced markedly reduced levels of ocular retinoids. Ophthalmic imaging and histology revealed malformations in the choroid and retinal pigmented epithelium, early cone photoreceptor cell death, and reduced lengths of rod outer segments. Similar to the blood-retina barrier in the RPE, vitamin A transport through the blood-cerebrospinal fluid barrier in the brain's choroid plexus was impaired. Notably, treatment with pharmacological doses of vitamin A restored vitamin A transport across these barriers and rescued the vision of Stra6(-/-) mice. Furthermore, under conditions mimicking vitamin A excess and deficiency, our analyses revealed that STRA6-mediated vitamin A uptake is a regulated process mandatory for ocular vitamin A uptake when RBP4 constitutes the only transport mode in vitamin A deficiency. These findings identifying STRA6 as a bona fide vitamin A transporter have important implications for disease states associated with impaired blood vitamin A homeostasis.
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Affiliation(s)
| | - Ning Zhang
- Department of Pharmacology, School of Medicine
| | | | - Tadao Maeda
- Department of Pharmacology, School of Medicine, Department of Ophthalmology, School of Medicine
| | - Krzysztof Palczewski
- Department of Pharmacology, School of Medicine, Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, Cleveland, OH 44106, USA
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85
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Lower fetuin-A, retinol binding protein 4 and several metabolites after gastric bypass compared to sleeve gastrectomy in patients with type 2 diabetes. PLoS One 2014; 9:e96489. [PMID: 24800810 PMCID: PMC4011803 DOI: 10.1371/journal.pone.0096489] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2013] [Accepted: 04/08/2014] [Indexed: 02/06/2023] Open
Abstract
Background Bypass of foregut secreted factors promoting insulin resistance is hypothesized to be one of the mechanisms by which resolution of type 2 diabetes (T2D) follows roux-en-y gastric bypass (GBP) surgery. Aim To identify insulin resistance-associated proteins and metabolites which decrease more after GBP than after sleeve gastrectomy (SG) prior to diabetes remission. Methods Fasting plasma from 15 subjects with T2D undergoing GBP or SG was analyzed by proteomic and metabolomic methods 3 days before and 3 days after surgery. Subjects were matched for age, BMI, metformin therapy and glycemic control. Insulin resistance was calculated using homeostasis model assessment (HOMA-IR). For proteomics, samples were depleted of abundant plasma proteins, digested with trypsin and labeled with iTRAQ isobaric tags prior to liquid chromatography-tandem mass spectrometry analysis. Metabolomic analysis was performed using gas chromatography-mass spectrometry. The effect of the respective bariatric surgery on identified proteins and metabolites was evaluated using two-way analysis of variance and appropriate post-hoc tests. Results HOMA-IR improved, albeit not significantly, in both groups after surgery. Proteomic analysis yielded seven proteins which decreased significantly after GBP only, including Fetuin-A and Retinol binding protein 4, both previously linked to insulin resistance. Significant decrease in Fetuin-A and Retinol binding protein 4 after GBP was confirmed using ELISA and immunoassay. Metabolomic analysis identified significant decrease of citrate, proline, histidine and decanoic acid specifically after GBP. Conclusion Greater early decrease was seen for Fetuin-A, Retinol binding protein 4, and several metabolites after GBP compared to SG, preceding significant weight loss. This may contribute to enhanced T2D remission observed following foregut bypass procedures.
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86
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Khillan JS. Vitamin A/retinol and maintenance of pluripotency of stem cells. Nutrients 2014; 6:1209-22. [PMID: 24662164 PMCID: PMC3967188 DOI: 10.3390/nu6031209] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Revised: 02/21/2014] [Accepted: 02/24/2014] [Indexed: 12/22/2022] Open
Abstract
Retinol, the alcohol form of vitamin A is a key dietary component that plays a critical role in vertebrate development, cell differentiation, reproduction, vision and immune system. Natural and synthetic analogs of retinol, called retinoids, have generally been associated with the cell differentiation via retinoic acid which is the most potent metabolite of retinol. However, a direct function of retinol has not been fully investigated. New evidence has now emerged that retinol supports the self-renewal of stem cells including embryonic stem cells (ESCs), germ line stem cells (GSCs) and cancer stem cells (CSCs) by activating the endogenous machinery for self-renewal by a retinoic acid independent mechanism. The studies have also revealed that stem cells do not contain enzymes that are responsible for metabolizing retinol into retinoic acid. This new function of retinol may have important implications for stem cell biology which can be exploited for quantitative production of pure population of pluripotent stem cells for regenerative medicine as well as clinical applications for cancer therapeutics.
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Affiliation(s)
- Jaspal S Khillan
- Department of Immunology, University of Pittsburgh, 3501 Fifth Ave, Pittsburgh, PA 15261, USA.
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87
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Downregulation of STRA6 in adipocytes and adipose stromovascular fraction in obesity and effects of adipocyte-specific STRA6 knockdown in vivo. Mol Cell Biol 2014; 34:1170-86. [PMID: 24421389 DOI: 10.1128/mcb.01106-13] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
To investigate the mechanisms by which elevated retinol-binding protein 4 (RBP4) causes insulin resistance, we studied the role of the high-affinity receptor for RBP4, STRA6 (stimulated by retinoic acid), in insulin resistance and obesity. In high-fat-diet-fed and ob/ob mice, STRA6 expression was decreased 70 to 95% in perigonadal adipocytes and both perigonadal and subcutaneous adipose stromovascular cells. To determine whether downregulation of STRA6 in adipocytes contributes to insulin resistance, we generated adipose-Stra6(-/-) mice. Adipose-Stra6(-/-) mice fed chow had decreased body weight, fat mass, leptin levels, insulin levels, and adipocyte number and increased expression of brown fat-selective markers in white adipose tissue. When fed a high-fat diet, these mice had a mild improvement in insulin sensitivity at an age when adiposity was unchanged. STRA6 has been implicated in retinol uptake, but retinol uptake and the expression of retinoid homeostatic genes (encoding retinoic acid receptor β [RARβ], CYP26A1, and lecithin retinol acyltransferase) were not altered in adipocytes from adipose-Stra6(-/-) mice, indicating that retinoid homeostasis was maintained with STRA6 knockdown. Thus, STRA6 reduction in adipocytes in adipose-Stra6(-/-) mice fed chow resulted in leanness, which may contribute to their increased insulin sensitivity. However, in wild-type mice with high-fat-diet-induced obesity and in ob/ob mice, the marked downregulation of STRA6 in adipocytes and adipose stromovascular cells does not compensate for obesity-associated insulin resistance.
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88
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Affiliation(s)
| | | | - Krzysztof Palczewski
- Department of Pharmacology, School of Medicine, Case
Western Reserve University, 2109 Adelbert Road, Cleveland, Ohio 44106-4965,
United States
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89
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Chen W, Howell ML, Li Y, Li R, Chen G. Vitamin A and feeding statuses modulate the insulin-regulated gene expression in Zucker lean and fatty primary rat hepatocytes. PLoS One 2014; 9:e100868. [PMID: 25105869 PMCID: PMC4126667 DOI: 10.1371/journal.pone.0100868] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Accepted: 05/30/2014] [Indexed: 02/07/2023] Open
Abstract
Unattended hepatic insulin resistance predisposes individuals to dyslipidemia, type 2 diabetes and many other metabolic complications. The mechanism of hepatic insulin resistance at the gene expression level remains unrevealed. To examine the effects of vitamin A (VA), total energy intake and feeding conditions on the insulin-regulated gene expression in primary hepatocytes of Zucker lean (ZL) and fatty (ZF) rats, we analyze the expression levels of hepatic model genes in response to the treatments of insulin and retinoic acid (RA). We report that the insulin- and RA-regulated glucokinase, sterol regulatory element-binding protein-1c and cytosolic form of phosphoenolpyruvate carboxykinase expressions are impaired in hepatocytes of ZF rats fed chow or a VA sufficient (VAS) diet ad libitum. The impairments are partially corrected when ZF rats are fed a VA deficient (VAD) diet ad libitum or pair-fed a VAS diet to the intake of their VAD counterparts in non-fasting conditions. Interestingly in the pair-fed ZL and ZF rats, transient overeating on the last day of pair-feeding regimen changes the expression levels of some VA catabolic genes, and impairs the insulin- and RA-regulated gene expression in hepatocytes. These results demonstrate that VA and feeding statuses modulate the hepatic insulin sensitivity at the gene expression level.
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Affiliation(s)
- Wei Chen
- Department of Nutrition, University of Tennessee at Knoxville, Knoxville, Tennessee, United States of America
| | - Meredith L. Howell
- Department of Nutrition, University of Tennessee at Knoxville, Knoxville, Tennessee, United States of America
| | - Yang Li
- Department of Nutrition, University of Tennessee at Knoxville, Knoxville, Tennessee, United States of America
| | - Rui Li
- Department of Nutrition, University of Tennessee at Knoxville, Knoxville, Tennessee, United States of America
| | - Guoxun Chen
- Department of Nutrition, University of Tennessee at Knoxville, Knoxville, Tennessee, United States of America
- * E-mail:
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90
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Terra R, Wang X, Hu Y, Charpentier T, Lamarre A, Zhong M, Sun H, Mao J, Qi S, Luo H, Wu J. To investigate the necessity of STRA6 upregulation in T cells during T cell immune responses. PLoS One 2013; 8:e82808. [PMID: 24391722 PMCID: PMC3876989 DOI: 10.1371/journal.pone.0082808] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Accepted: 11/06/2013] [Indexed: 12/12/2022] Open
Abstract
Our earlier study revealed that STRA6 (stimulated by retinoic acid gene 6) was up-regulated within 3 h of TCR stimulation. STRA6 is the high-affinity receptor for plasma retinol-binding protein (RBP) and mediates cellular vitamin A uptake. We generated STRA6 knockout (KO) mice to assess whether such up-regulation was critical for T-cell activation, differentiation and function. STRA6 KO mice under vitamin A sufficient conditions were fertile without apparent anomalies upon visual inspection. The size, cellularity and lymphocyte subpopulations of STRA6 KO thymus and spleen were comparable to those of their wild type (WT) controls. KO and WT T cells were similar in terms of TCR-stimulated proliferation in vitro and homeostatic expansion in vivo. Naive KO CD4 cells differentiated in vitro into Th1, Th2, Th17 as well as regulatory T cells in an analogous manner as their WT counterparts. In vivo experiments revealed that anti-viral immune responses to lymphocytic choriomeningitis virus in KO mice were comparable to those of WT controls. We also demonstrated that STRA6 KO and WT mice had similar glucose tolerance. Total vitamin A levels are dramatically lower in the eyes of KO mice as compared to those of WT mice, but the levels in other organs were not significantly affected after STRA6 deletion under vitamin A sufficient conditions, indicating that the eye is the mouse organ most sensitive to the loss of STRA6. Our results demonstrate that 1) in vitamin A sufficiency, the deletion of STRA6 in T cells does no affect the T-cell immune responses so-far tested, including those depend on STAT5 signaling; 2) STRA6-independent vitamin A uptake compensated the lack of STRA6 in lymphoid organs under vitamin A sufficient conditions in mice; 3) STRA6 is critical for vitamin A uptake in the eyes even in vitamin A sufficiency.
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Affiliation(s)
- Rafik Terra
- Laboratoire d'immunologie, Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM) – Hôpital Notre-Dame, Montréal, Québec, Canada
| | - Xuehai Wang
- Laboratoire d'immunologie, Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM) – Hôpital Notre-Dame, Montréal, Québec, Canada
| | - Yan Hu
- Laboratoire d'immunologie, Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM) – Hôpital Notre-Dame, Montréal, Québec, Canada
| | - Tania Charpentier
- Institut national de la recherche scientifique (INRS) – Institut Armand-Frappier, Laval, Québec, Canada
| | - Alain Lamarre
- Institut national de la recherche scientifique (INRS) – Institut Armand-Frappier, Laval, Québec, Canada
| | - Ming Zhong
- Department of Physiology, Jules Stein Eye Institute, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Hui Sun
- Department of Physiology, Jules Stein Eye Institute, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Jianning Mao
- Laboratoire d'immunologie, Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM) – Hôpital Notre-Dame, Montréal, Québec, Canada
| | - Shijie Qi
- Laboratoire d'immunologie, Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM) – Hôpital Notre-Dame, Montréal, Québec, Canada
| | - Hongyu Luo
- Laboratoire d'immunologie, Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM) – Hôpital Notre-Dame, Montréal, Québec, Canada
| | - Jiangping Wu
- Laboratoire d'immunologie, Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM) – Hôpital Notre-Dame, Montréal, Québec, Canada
- Service de néphrologie, Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM) – Hôpital Notre-Dame, Montréal, Québec, Canada
- * E-mail:
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91
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Álvarez R, Vaz B, Gronemeyer H, de Lera ÁR. Functions, therapeutic applications, and synthesis of retinoids and carotenoids. Chem Rev 2013; 114:1-125. [PMID: 24266866 DOI: 10.1021/cr400126u] [Citation(s) in RCA: 151] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Rosana Álvarez
- Departamento de Química Orgánica, Centro de Investigación Biomédica (CINBIO), and Instituto de Investigación Biomédica de Vigo (IBIV), Universidade de Vigo , 36310 Vigo, Spain
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92
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Zhong M, Kawaguchi R, Ter-Stepanian M, Kassai M, Sun H. Vitamin A transport and the transmembrane pore in the cell-surface receptor for plasma retinol binding protein. PLoS One 2013; 8:e73838. [PMID: 24223695 PMCID: PMC3815300 DOI: 10.1371/journal.pone.0073838] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Accepted: 07/25/2013] [Indexed: 11/18/2022] Open
Abstract
Vitamin A and its derivatives (retinoids) play diverse and crucial functions from embryogenesis to adulthood and are used as therapeutic agents in human medicine for eye and skin diseases, infections and cancer. Plasma retinol binding protein (RBP) is the principal and specific vitamin A carrier in the blood and binds vitamin A at 1∶1 ratio. STRA6 is the high-affinity membrane receptor for RBP and mediates cellular vitamin A uptake. STRA6 null mice have severely depleted vitamin A reserves for vision and consequently have vision loss, even under vitamin A sufficient conditions. STRA6 null humans have a wide range of severe pathological phenotypes in many organs including the eye, brain, heart and lung. Known membrane transport mechanisms involve transmembrane pores that regulate the transport of the substrate (e.g., the gating of ion channels). STRA6 represents a new type of membrane receptor. How this receptor interacts with its transport substrate vitamin A and the functions of its nine transmembrane domains are still completely unknown. These questions are critical to understanding the molecular basis of STRA6′s activities and its regulation. We employ acute chemical modification to introduce chemical side chains to STRA6 in a site-specific manner. We found that modifications with specific chemicals at specific positions in or near the transmembrane domains of this receptor can almost completely suppress its vitamin A transport activity. These experiments provide the first evidence for the existence of a transmembrane pore, analogous to the pore of ion channels, for this new type of cell-surface receptor.
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Affiliation(s)
- Ming Zhong
- Department of Physiology, Jules Stein Eye Institute, and Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
| | - Riki Kawaguchi
- Department of Physiology, Jules Stein Eye Institute, and Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
| | - Mariam Ter-Stepanian
- Department of Physiology, Jules Stein Eye Institute, and Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
| | - Miki Kassai
- Department of Physiology, Jules Stein Eye Institute, and Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
| | - Hui Sun
- Department of Physiology, Jules Stein Eye Institute, and Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
- * E-mail:
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93
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Chen G. Roles of Vitamin A Metabolism in the Development of Hepatic Insulin Resistance. ISRN HEPATOLOGY 2013; 2013:534972. [PMID: 27335827 PMCID: PMC4890907 DOI: 10.1155/2013/534972] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Accepted: 08/18/2013] [Indexed: 02/07/2023]
Abstract
The increase in the number of people with obesity- and noninsulin-dependent diabetes mellitus has become a major public health concern. Insulin resistance is a common feature closely associated with human obesity and diabetes. Insulin regulates metabolism, at least in part, via the control of the expression of the hepatic genes involved in glucose and fatty acid metabolism. Insulin resistance is always associated with profound changes of the expression of hepatic genes for glucose and lipid metabolism. As an essential micronutrient, vitamin A (VA) is needed in a variety of physiological functions. The active metablite of VA, retinoic acid (RA), regulates the expression of genes through the activation of transcription factors bound to the RA-responsive elements in the promoters of RA-targeted genes. Recently, retinoids have been proposed to play roles in glucose and lipid metabolism and energy homeostasis. This paper summarizes the recent progresses in our understanding of VA metabolism in the liver and of the potential transcription factors mediating RA responses. These transcription factors are the retinoic acid receptor, the retinoid X receptor, the hepatocyte nuclear factor 4α, the chicken ovalbumin upstream promoter-transcription factor II, and the peroxisome proliferator-activated receptor β/δ. This paper also summarizes the effects of VA status and RA treatments on the glucose and lipid metabolism in vivo and the effects of retinoid treatments on the expression of insulin-regulated genes involved in the glucose and fatty acid metabolism in the primary hepatocytes. I discuss the roles of RA production in the development of insulin resistance in hepatocytes and proposes a mechanism by which RA production may contribute to hepatic insulin resistance. Given the large amount of information and progresses regarding the physiological functions of VA, this paper mainly focuses on the findings in the liver and hepatocytes and only mentions the relative findings in other tissues and cells.
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Affiliation(s)
- Guoxun Chen
- Department of Nutrition, University of Tennessee at Knoxville, Knoxville, TN 37996, USA
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94
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Reboul E. Absorption of vitamin A and carotenoids by the enterocyte: focus on transport proteins. Nutrients 2013; 5:3563-81. [PMID: 24036530 PMCID: PMC3798921 DOI: 10.3390/nu5093563] [Citation(s) in RCA: 181] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 08/19/2013] [Accepted: 08/26/2013] [Indexed: 12/15/2022] Open
Abstract
Vitamin A deficiency is a public health problem in most developing countries, especially in children and pregnant women. It is thus a priority in health policy to improve preformed vitamin A and/or provitamin A carotenoid status in these individuals. A more accurate understanding of the molecular mechanisms of intestinal vitamin A absorption is a key step in this direction. It was long thought that β-carotene (the main provitamin A carotenoid in human diet), and thus all carotenoids, were absorbed by a passive diffusion process, and that preformed vitamin A (retinol) absorption occurred via an unidentified energy-dependent transporter. The discovery of proteins able to facilitate carotenoid uptake and secretion by the enterocyte during the past decade has challenged established assumptions, and the elucidation of the mechanisms of retinol intestinal absorption is in progress. After an overview of vitamin A and carotenoid fate during gastro-duodenal digestion, our focus will be directed to the putative or identified proteins participating in the intestinal membrane and cellular transport of vitamin A and carotenoids across the enterocyte (i.e., Scavenger Receptors or Cellular Retinol Binding Proteins, among others). Further progress in the identification of the proteins involved in intestinal transport of vitamin A and carotenoids across the enterocyte is of major importance for optimizing their bioavailability.
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Affiliation(s)
- Emmanuelle Reboul
- INRA, UMR1260, Nutrition, Obesity and Risk of Thrombosis, Marseille F-13385, France.
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95
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Retinol-binding protein 4 and its membrane receptor STRA6 control adipogenesis by regulating cellular retinoid homeostasis and retinoic acid receptor α activity. Mol Cell Biol 2013; 33:4068-82. [PMID: 23959802 DOI: 10.1128/mcb.00221-13] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Retinoids are vitamin A (retinol) derivatives and complex regulators of adipogenesis by activating specific nuclear receptors, including the retinoic acid receptor (RAR) and retinoid X receptor (RXR). Circulating retinol-binding protein 4 (RBP4) and its membrane receptor STRA6 coordinate cellular retinol uptake. It is unknown whether retinol levels and the activity of RAR and RXR in adipocyte precursors are linked via RBP4/STRA6. Here, we show that STRA6 is expressed in precursor cells and, dictated by the apo- and holo-RBP4 isoforms, mediates bidirectional retinol transport that controls RARα activity and subsequent adipocyte differentiation. Mobilization of retinoid stores in mice by inducing RBP4 secretion from the liver activated RARα signaling in the precursor cell containing the stromal-vascular fraction of adipose tissue. Retinol-loaded holo-RBP4 blocked adipocyte differentiation of cultured precursors by activating RARα. Remarkably, retinol-free apo-RBP4 triggered retinol efflux that reduced cellular retinoids, RARα activity, and target gene expression and enhanced adipogenesis synergistically with ectopic STRA6. Thus, STRA6 in adipocyte precursor cells links nuclear RARα activity to the circulating RBP4 isoforms, whose ratio in obese mice was shifted toward limiting the adipogenic potential of their precursors. This novel cross talk identifies a retinol-dependent metabolic function of RBP4 that may have important implications for the treatment of obesity.
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96
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Maher JJ. Retinol binding protein 4 and fatty liver: A direct link? Hepatology 2013; 58:477-9. [PMID: 23703940 PMCID: PMC3729862 DOI: 10.1002/hep.26507] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Accepted: 03/25/2013] [Indexed: 12/07/2022]
Affiliation(s)
- Jacquelyn J. Maher
- Liver Center and Department of Medicine, University of California, San Francisco
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97
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Berry DC, Jacobs H, Marwarha G, Gely-Pernot A, O'Byrne SM, DeSantis D, Klopfenstein M, Feret B, Dennefeld C, Blaner WS, Croniger CM, Mark M, Noy N, Ghyselinck NB. The STRA6 receptor is essential for retinol-binding protein-induced insulin resistance but not for maintaining vitamin A homeostasis in tissues other than the eye. J Biol Chem 2013; 288:24528-39. [PMID: 23839944 DOI: 10.1074/jbc.m113.484014] [Citation(s) in RCA: 106] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The plasma membrane protein STRA6 is thought to mediate uptake of retinol from its blood carrier retinol-binding protein (RBP) into cells and to function as a surface receptor that, upon binding of holo-RBP, activates a JAK/STAT cascade. It was suggested that STRA6 signaling underlies insulin resistance induced by elevated serum levels of RBP in obese animals. To investigate these activities in vivo, we generated and analyzed Stra6-null mice. We show that the contribution of STRA6 to retinol uptake by tissues in vivo is small and that, with the exception of the eye, ablation of Stra6 has only a modest effect on retinoid homeostasis and does not impair physiological functions that critically depend on retinoic acid in the embryo or in the adult. However, ablation of Stra6 effectively protects mice from RBP-induced suppression of insulin signaling. Thus one biological function of STRA6 in tissues other than the eye appears to be the coupling of circulating holo-RBP levels to cell signaling, in turn regulating key processes such as insulin response.
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Affiliation(s)
- Daniel C Berry
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA
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98
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Gyöngyösi A, Szatmari I, Pap A, Dezso B, Pos Z, Széles L, Varga T, Nagy L. RDH10, RALDH2, and CRABP2 are required components of PPARγ-directed ATRA synthesis and signaling in human dendritic cells. J Lipid Res 2013; 54:2458-74. [PMID: 23833249 DOI: 10.1194/jlr.m038984] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
All-trans retinoic acid (ATRA) has a key role in dendritic cells (DCs) and affects T cell subtype specification and gut homing. However, the identity of the permissive cell types and the required steps of conversion of vitamin A to biologically active ATRA bringing about retinoic acid receptor-regulated signaling remains elusive. Here we present that only a subset of murine and human DCs express the necessary enzymes, including RDH10, RALDH2, and transporter cellular retinoic acid binding protein (CRABP)2, to produce ATRA and efficient signaling. These permissive cell types include CD103(+) DCs, granulocyte-macrophage colony-stimulating factor, and interleukin-4-treated bone marrow-derived murine DCs and human monocyte-derived DCs (mo-DCs). Importantly, in addition to RDH10 and RALDH2, CRABP2 also appears to be regulated by the fatty acid-sensing nuclear receptor peroxisome proliferator-activated receptor γ (PPARγ) and colocalize in human gut-associated lymphoid tissue DCs. In our model of human mo-DCs, all three proteins (RDH10, RALDH2, and CRABP2) appeared to be required for ATRA production induced by activation of PPARγ and therefore form a linear pathway. This now functionally validated PPARγ-regulated ATRA producing and signaling axis equips the cells with the capacity to convert precursors to active retinoids in response to receptor-activating fatty acids and is potentially amenable to intervention in diseases involving or affecting mucosal immunity.
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Affiliation(s)
- Adrienn Gyöngyösi
- Department of Biochemistry and Molecular Biology, Research Center for Molecular Medicine, University of Debrecen, Medical and Health Science Center, Debrecen, Hungary
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99
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O'Byrne SM, Blaner WS. Retinol and retinyl esters: biochemistry and physiology. J Lipid Res 2013; 54:1731-43. [PMID: 23625372 PMCID: PMC3679378 DOI: 10.1194/jlr.r037648] [Citation(s) in RCA: 236] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 04/24/2013] [Indexed: 12/23/2022] Open
Abstract
By definition, a vitamin is a substance that must be obtained regularly from the diet. Vitamin A must be acquired from the diet, but unlike most vitamins, it can also be stored within the body in relatively high levels. For humans living in developed nations or animals living in present-day vivariums, stored vitamin A concentrations can become relatively high, reaching levels that can protect against the adverse effects of insufficient vitamin A dietary intake for six months, or even much longer. The ability to accumulate vitamin A stores lessens the need for routinely consuming vitamin A in the diet, and this provides a selective advantage to the organism. The molecular processes that underlie this selective advantage include efficient mechanisms to acquire vitamin A from the diet, efficient and overlapping mechanisms for the transport of vitamin A in the circulation, a specific mechanism allowing for vitamin A storage, and a mechanism for mobilizing vitamin A from these stores in response to tissue needs. These processes are considered in this review.
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Affiliation(s)
- Sheila M. O'Byrne
- Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, NY 10032
| | - William S. Blaner
- Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, NY 10032
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100
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Kedishvili NY. Enzymology of retinoic acid biosynthesis and degradation. J Lipid Res 2013; 54:1744-60. [PMID: 23630397 PMCID: PMC3679379 DOI: 10.1194/jlr.r037028] [Citation(s) in RCA: 140] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 04/17/2013] [Indexed: 12/18/2022] Open
Abstract
All-trans-retinoic acid is a biologically active derivative of vitamin A that regulates numerous physiological processes. The concentration of retinoic acid in the cells is tightly regulated, but the exact mechanisms responsible for this regulation are not completely understood, largely because the enzymes involved in the biosynthesis of retinoic acid have not been fully defined. Recent studies using in vitro and in vivo models suggest that several members of the short-chain dehydrogenase/reductase superfamily of proteins are essential for retinoic acid biosynthesis and the maintenance of retinoic acid homeostasis. However, the exact roles of some of these recently identified enzymes are yet to be characterized. The properties of the known contributors to retinoid metabolism have now been better defined and allow for more detailed understanding of their interactions with retinoid-binding proteins and other retinoid enzymes. At the same time, further studies are needed to clarify the interactions between the cytoplasmic and membrane-bound proteins involved in the processing of hydrophobic retinoid metabolites. This review summarizes current knowledge about the roles of various biosynthetic and catabolic enzymes in the regulation of retinoic acid homeostasis and outlines the remaining questions in the field.
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Affiliation(s)
- Natalia Y Kedishvili
- Department of Biochemistry and Molecular Genetics, Schools of Medicine and Dentistry, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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