1
|
Bohn T, Hellman-Regen J, de Lera AR, Böhm V, Rühl R. Human nutritional relevance and suggested nutritional guidelines for vitamin A5/X and provitamin A5/X. Nutr Metab (Lond) 2023; 20:34. [PMID: 37582723 PMCID: PMC10426203 DOI: 10.1186/s12986-023-00750-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 05/27/2023] [Indexed: 08/17/2023] Open
Abstract
In the last century, vitamin A was identified that included the nutritional relevant vitamin A1 / provitamin A1, as well as the vitamin A2 pathway concept. Globally, nutritional guidelines have focused on vitamin A1 with simplified recommendations and calculations based solely on vitamin A. The vitamin A / provitamin A terminology described vitamin A with respect to acting as a precursor of 11-cis-retinal, the chromophore of the visual pigment, as well as retinoic acid(s), being ligand(s) of the nuclear hormone receptors retinoic acid receptors (RARs) α, β and γ. All-trans-retinoic acid was conclusively shown to be the endogenous RAR ligand, while the concept of its isomer 9-cis-retinoic acid, being "the" endogenous ligand of the retinoid-X receptors (RXRs), remained inconclusive. Recently, 9-cis-13,14-dihydroretinoic acid was conclusively reported as an endogenous RXR ligand, and a direct nutritional precursor was postulated in 2018 and further confirmed by Rühl, Krezel and de Lera in 2021. This was further termed vitamin A5/X / provitamin A5/X. In this review, a new vitamin A5/X / provitamin A5/X concept is conceptualized in parallel to the vitamin A(1) / provitamin A(1) concept for daily dietary intake and towards dietary guidelines, with a focus on the existing national and international regulations for the physiological and nutritional relevance of vitamin A5/X. The aim of this review is to summarize available evidence and to emphasize gaps of knowledge regarding vitamin A5/X, based on new and older studies and proposed future directions as well as to stimulate and propose adapted nutritional regulations.
Collapse
Affiliation(s)
- Torsten Bohn
- Nutrition Research Group, Department of Precision Health, Luxembourg Institute and Health, 1 A-B, Rue Thomas Edison, 1445, Strassen, Luxembourg
| | - Julian Hellman-Regen
- Department of Psychiatry, Charité-Campus Benjamin Franklin, Section Neurobiology, University Medicine Berlin, Berlin, Germany
| | - Angel R de Lera
- Departamento de Química Orgánica, Facultad de Química, CINBIO and IBIV, Universidade de Vigo, Campus As Lagoas-Marcosende, 36310, Vigo, Spain
| | - Volker Böhm
- Institute of Nutritional Sciences, Friedrich Schiller University Jena, Jena, Germany
| | - Ralph Rühl
- CISCAREX UG, Transvaalstr. 27c, 13351, Berlin, Germany.
| |
Collapse
|
2
|
Sahu B, Maeda A. Retinol Dehydrogenases Regulate Vitamin A Metabolism for Visual Function. Nutrients 2016; 8:E746. [PMID: 27879662 PMCID: PMC5133129 DOI: 10.3390/nu8110746] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 11/13/2016] [Accepted: 11/16/2016] [Indexed: 02/07/2023] Open
Abstract
The visual system produces visual chromophore, 11-cis-retinal from dietary vitamin A, all-trans-retinol making this vitamin essential for retinal health and function. These metabolic events are mediated by a sequential biochemical process called the visual cycle. Retinol dehydrogenases (RDHs) are responsible for two reactions in the visual cycle performed in retinal pigmented epithelial (RPE) cells, photoreceptor cells and Müller cells in the retina. RDHs in the RPE function as 11-cis-RDHs, which oxidize 11-cis-retinol to 11-cis-retinal in vivo. RDHs in rod photoreceptor cells in the retina work as all-trans-RDHs, which reduce all-trans-retinal to all-trans-retinol. Dysfunction of RDHs can cause inherited retinal diseases in humans. To facilitate further understanding of human diseases, mouse models of RDHs-related diseases have been carefully examined and have revealed the physiological contribution of specific RDHs to visual cycle function and overall retinal health. Herein we describe the function of RDHs in the RPE and the retina, particularly in rod photoreceptor cells, their regulatory properties for retinoid homeostasis and future therapeutic strategy for treatment of retinal diseases.
Collapse
Affiliation(s)
- Bhubanananda Sahu
- Department of Ophthalmology and Visual Sciences, School of Medicine, Case Western Reserve University, Cleveland, OH 44106-4965, USA.
| | - Akiko Maeda
- Department of Ophthalmology and Visual Sciences, School of Medicine, Case Western Reserve University, Cleveland, OH 44106-4965, USA.
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH 44106-4965, USA.
| |
Collapse
|
3
|
de Lera ÁR, Krezel W, Rühl R. An Endogenous Mammalian Retinoid X Receptor Ligand, At Last! ChemMedChem 2016; 11:1027-37. [PMID: 27151148 DOI: 10.1002/cmdc.201600105] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 03/15/2016] [Indexed: 12/27/2022]
Abstract
9-cis-Retinoic acid was identified and claimed to be the endogenous ligand of the retinoid X receptors (RXRs) in 1992. Since then, the endogenous presence of this compound has never been rigorously confirmed. Instead, concerns have been raised by other groups that have reported that 9-cis-retinoic acid is undetectable or that its presence occurs at very low levels. Furthermore, these low levels could not satisfactorily explain the physiological activation of RXR. Alternative ligands, among them various lipids, have also been identified, but also did not fulfill criteria for rigorous endogenous relevance, and their consideration as bona fide endogenous mammalian RXR ligand has likewise been questioned. Recently, novel studies claim that the saturated analogue 9-cis-13,14-dihydroretinoic acid functions as an endogenous physiologically relevant mammalian RXR ligand.
Collapse
Affiliation(s)
- Ángel R de Lera
- Departamento de Química Orgánica, Facultade de Química, CINBIO and IBIV, Universidade de Vigo, Campus As Lagoas-Marcosende, 36310, Vigo, Spain.
| | - Wojciech Krezel
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Institut de la Santé et de la Recherche Médicale, U964, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7104, Université de Strasbourg, Fédération de Médecine Translationnelle de Strasbourg, 67404, Illkirch, France
| | - Ralph Rühl
- Paprika Bioanalytics BT, Debrecen, Hungary.,MTA-DE, Public Health Research Group of the Hungarian Academy of Sciences, Faculty of Public Health, University of Debrecen, Hungary
| |
Collapse
|
4
|
Lhor M, Salesse C. Retinol dehydrogenases: membrane-bound enzymes for the visual function. Biochem Cell Biol 2014; 92:510-23. [PMID: 25357265 DOI: 10.1139/bcb-2014-0082] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Retinoid metabolism is important for many physiological functions, such as differenciation, growth, and vision. In the visual context, after the absorption of light in rod photoreceptors by the visual pigment rhodopsin, 11-cis retinal is isomerized to all-trans retinal. This retinoid subsequently undergoes a series of modifications during the visual cycle through a cascade of reactions occurring in photoreceptors and in the retinal pigment epithelium. Retinol dehydrogenases (RDHs) are enzymes responsible for crucial steps of this visual cycle. They belong to a large family of proteins designated as short-chain dehydrogenases/reductases. The structure of these RDHs has been predicted using modern bioinformatics tools, which allowed to propose models with similar structures including a common Rossman fold. These enzymes undergo oxidoreduction reactions, whose direction is dictated by the preference and concentration of their individual cofactor (NAD(H)/NADP(H)). This review presents the current state of knowledge on functional and structural features of RDHs involved in the visual cycle as well as knockout models. RDHs are described as integral or peripheral enzymes. A topology model of the membrane binding of these RDHs via their N- and (or) C-terminal domain has been proposed on the basis of their individual properties. Membrane binding is a crucial issue for these enzymes because of the high hydrophobicity of their retinoid substrates.
Collapse
Affiliation(s)
- Mustapha Lhor
- a CUO-Recherche, Centre de recherche du CHU de Québec, Hôpital du Saint Sacrement, Département d'ophtalmologie, Faculté de médicine, Université Laval, Québec, QC G1S 4L8, Canada
| | | |
Collapse
|
5
|
Lhor M, Bernier SC, Horchani H, Bussières S, Cantin L, Desbat B, Salesse C. Comparison between the behavior of different hydrophobic peptides allowing membrane anchoring of proteins. Adv Colloid Interface Sci 2014; 207:223-39. [PMID: 24560216 PMCID: PMC4028306 DOI: 10.1016/j.cis.2014.01.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 01/11/2014] [Accepted: 01/13/2014] [Indexed: 10/25/2022]
Abstract
Membrane binding of proteins such as short chain dehydrogenase reductases or tail-anchored proteins relies on their N- and/or C-terminal hydrophobic transmembrane segment. In this review, we propose guidelines to characterize such hydrophobic peptide segments using spectroscopic and biophysical measurements. The secondary structure content of the C-terminal peptides of retinol dehydrogenase 8, RGS9-1 anchor protein, lecithin retinol acyl transferase, and of the N-terminal peptide of retinol dehydrogenase 11 has been deduced by prediction tools from their primary sequence as well as by using infrared or circular dichroism analyses. Depending on the solvent and the solubilization method, significant structural differences were observed, often involving α-helices. The helical structure of these peptides was found to be consistent with their presumed membrane binding. Langmuir monolayers have been used as membrane models to study lipid-peptide interactions. The values of maximum insertion pressure obtained for all peptides using a monolayer of 1,2-dioleoyl-sn-glycero-3-phospho-ethanolamine (DOPE) are larger than the estimated lateral pressure of membranes, thus suggesting that they bind membranes. Polarization modulation infrared reflection absorption spectroscopy has been used to determine the structure and orientation of these peptides in the absence and in the presence of a DOPE monolayer. This lipid induced an increase or a decrease in the organization of the peptide secondary structure. Further measurements are necessary using other lipids to better understand the membrane interactions of these peptides.
Collapse
Affiliation(s)
- Mustapha Lhor
- CUO-Recherche, Centre de recherche du CHU de Québec, Hôpital du Saint-Sacrement, Département d'ophtalmologie, Faculté de médecine, Université Laval, Québec, Québec G1V 0A6, Canada; Regroupement stratégique PROTEO, Université Laval, Québec, Québec G1V 0A6, Canada
| | - Sarah C Bernier
- CUO-Recherche, Centre de recherche du CHU de Québec, Hôpital du Saint-Sacrement, Département d'ophtalmologie, Faculté de médecine, Université Laval, Québec, Québec G1V 0A6, Canada; Regroupement stratégique PROTEO, Université Laval, Québec, Québec G1V 0A6, Canada
| | - Habib Horchani
- CUO-Recherche, Centre de recherche du CHU de Québec, Hôpital du Saint-Sacrement, Département d'ophtalmologie, Faculté de médecine, Université Laval, Québec, Québec G1V 0A6, Canada; Regroupement stratégique PROTEO, Université Laval, Québec, Québec G1V 0A6, Canada
| | - Sylvain Bussières
- CUO-Recherche, Centre de recherche du CHU de Québec, Hôpital du Saint-Sacrement, Département d'ophtalmologie, Faculté de médecine, Université Laval, Québec, Québec G1V 0A6, Canada; Regroupement stratégique PROTEO, Université Laval, Québec, Québec G1V 0A6, Canada
| | - Line Cantin
- CUO-Recherche, Centre de recherche du CHU de Québec, Hôpital du Saint-Sacrement, Département d'ophtalmologie, Faculté de médecine, Université Laval, Québec, Québec G1V 0A6, Canada; Regroupement stratégique PROTEO, Université Laval, Québec, Québec G1V 0A6, Canada
| | - Bernard Desbat
- CBMN-UMR 5248 CNRS, Université de Bordeaux, IPB, Allée Geoffroy Saint Hilaire, 33600 Pessac, France
| | - Christian Salesse
- CUO-Recherche, Centre de recherche du CHU de Québec, Hôpital du Saint-Sacrement, Département d'ophtalmologie, Faculté de médecine, Université Laval, Québec, Québec G1V 0A6, Canada; Regroupement stratégique PROTEO, Université Laval, Québec, Québec G1V 0A6, Canada.
| |
Collapse
|
6
|
Dalfó D, Marqués N, Albalat R. Analysis of the NADH-dependent retinaldehyde reductase activity of amphioxus retinol dehydrogenase enzymes enhances our understanding of the evolution of the retinol dehydrogenase family. FEBS J 2007; 274:3739-3752. [PMID: 17608724 DOI: 10.1111/j.1742-4658.2007.05904.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In vertebrates, multiple microsomal retinol dehydrogenases are involved in reversible retinol/retinal interconversion, thereby controlling retinoid metabolism and retinoic acid availability. The physiologic functions of these enzymes are not, however, fully understood, as each vertebrate form has several, usually overlapping, biochemical roles. Within this context, amphioxus, a group of chordates that are simpler, at both the functional and genomic levels, than vertebrates, provides a suitable evolutionary model for comparative studies of retinol dehydrogenase enzymes. In a previous study, we identified two amphioxus enzymes, Branchiostoma floridae retinol dehydrogenase 1 and retinol dehydrogenase 2, both candidates to be the cephalochordate orthologs of the vertebrate retinol dehydrogenase enzymes. We have now proceeded to characterize these amphioxus enzymes. Kinetic studies have revealed that retinol dehydrogenase 1 and retinol dehydrogenase 2 are microsomal proteins that catalyze the reduction of all-trans-retinaldehyde using NADH as cofactor, a remarkable combination of substrate and cofactor preferences. Moreover, evolutionary analysis, including the amphioxus sequences, indicates that Rdh genes were extensively duplicated after cephalochordate divergence, leading to the gene cluster organization found in several mammalian species. Overall, our data provide an evolutionary reference with which to better understand the origin, activity and evolution of retinol dehydrogenase enzymes.
Collapse
Affiliation(s)
- Diana Dalfó
- Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, Spain
| | - Neus Marqués
- Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, Spain
| | - Ricard Albalat
- Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, Spain
| |
Collapse
|
7
|
Abstract
Specific proteins in the nucleus act as transcription factors upon activation through binding of small molecules (all-trans-retinoic acid, thyroid hormone, vitamin D, and others). The activated (liganded) receptors bind to specific DNA elements as heterodimers, each in combination with the retinoic acid-X receptor (RXR). 9-Cis-retinoic acid binds to RXR with high affinity and activates it. Though 9-cis-retinoic acid was initially found in animal tissues, in later work 9-cis-retinoic acid could not be detected. A search for a ligand for RXR in tissues showed that unsaturated fatty acids, particularly linoleic, linolenic, and docosahexaenoic acids, bound to and activated RXR as specific ligands, although with low affinity. A critical experiment demonstrated that, at least in developing mouse skin, 9-cis-retinoic acid is not the ligand for RXR.
Collapse
Affiliation(s)
- George Wolf
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, USA
| |
Collapse
|
8
|
Gallego O, Belyaeva O, Porté S, Ruiz F, Stetsenko A, Shabrova E, Kostereva N, Farrés J, Parés X, Kedishvili N. Comparative functional analysis of human medium-chain dehydrogenases, short-chain dehydrogenases/reductases and aldo-keto reductases with retinoids. Biochem J 2006; 399:101-9. [PMID: 16787387 PMCID: PMC1570161 DOI: 10.1042/bj20051988] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Retinoic acid biosynthesis in vertebrates occurs in two consecutive steps: the oxidation of retinol to retinaldehyde followed by the oxidation of retinaldehyde to retinoic acid. Enzymes of the MDR (medium-chain dehydrogenase/reductase), SDR (short-chain dehydrogenase/reductase) and AKR (aldo-keto reductase) superfamilies have been reported to catalyse the conversion between retinol and retinaldehyde. Estimation of the relative contribution of enzymes of each type was difficult since kinetics were performed with different methodologies, but SDRs would supposedly play a major role because of their low K(m) values, and because they were found to be active with retinol bound to CRBPI (cellular retinol binding protein type I). In the present study we employed detergent-free assays and HPLC-based methodology to characterize side-by-side the retinoid-converting activities of human MDR [ADH (alcohol dehydrogenase) 1B2 and ADH4), SDR (RoDH (retinol dehydrogenase)-4 and RDH11] and AKR (AKR1B1 and AKR1B10) enzymes. Our results demonstrate that none of the enzymes, including the SDR members, are active with CRBPI-bound retinoids, which questions the previously suggested role of CRBPI as a retinol supplier in the retinoic acid synthesis pathway. The members of all three superfamilies exhibit similar and low K(m) values for retinoids (0.12-1.1 microM), whilst they strongly differ in their kcat values, which range from 0.35 min(-1) for AKR1B1 to 302 min(-1) for ADH4. ADHs appear to be more effective retinol dehydrogenases than SDRs because of their higher kcat values, whereas RDH11 and AKR1B10 are efficient retinaldehyde reductases. Cell culture studies support a role for RoDH-4 as a retinol dehydrogenase and for AKR1B1 as a retinaldehyde reductase in vivo.
Collapse
Affiliation(s)
- Oriol Gallego
- *Department of Biochemistry and Molecular Biology, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Barcelona, Spain
| | - Olga V. Belyaeva
- †Department of Biochemistry and Molecular Genetics, Schools of Medicine and Dentistry, University of Alabama at Birmingham, Birmingham, AL 35294, U.S.A
| | - Sergio Porté
- *Department of Biochemistry and Molecular Biology, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Barcelona, Spain
| | - F. Xavier Ruiz
- *Department of Biochemistry and Molecular Biology, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Barcelona, Spain
| | - Anton V. Stetsenko
- †Department of Biochemistry and Molecular Genetics, Schools of Medicine and Dentistry, University of Alabama at Birmingham, Birmingham, AL 35294, U.S.A
| | - Elena V. Shabrova
- †Department of Biochemistry and Molecular Genetics, Schools of Medicine and Dentistry, University of Alabama at Birmingham, Birmingham, AL 35294, U.S.A
| | - Natalia V. Kostereva
- †Department of Biochemistry and Molecular Genetics, Schools of Medicine and Dentistry, University of Alabama at Birmingham, Birmingham, AL 35294, U.S.A
| | - Jaume Farrés
- *Department of Biochemistry and Molecular Biology, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Barcelona, Spain
| | - Xavier Parés
- *Department of Biochemistry and Molecular Biology, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Barcelona, Spain
| | - Natalia Y. Kedishvili
- †Department of Biochemistry and Molecular Genetics, Schools of Medicine and Dentistry, University of Alabama at Birmingham, Birmingham, AL 35294, U.S.A
- To whom correspondence should be addressed (email )
| |
Collapse
|
9
|
Lidén M, Eriksson U. Understanding Retinol Metabolism: Structure and Function of Retinol Dehydrogenases. J Biol Chem 2006; 281:13001-13004. [PMID: 16428379 DOI: 10.1074/jbc.r500027200] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Martin Lidén
- Ludwig Institute for Cancer Research, Stockholm Branch, Box 240, S-171 77 Stockholm, Sweden
| | - Ulf Eriksson
- Ludwig Institute for Cancer Research, Stockholm Branch, Box 240, S-171 77 Stockholm, Sweden.
| |
Collapse
|
10
|
Lidén M, Tryggvason K, Eriksson U. The C-terminal region of cis-retinol/androgen dehydrogenase 1 (CRAD1) confers ER localization and in vivo enzymatic function. Exp Cell Res 2005; 311:205-17. [PMID: 16223484 DOI: 10.1016/j.yexcr.2005.07.032] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2005] [Revised: 07/27/2005] [Accepted: 07/27/2005] [Indexed: 01/19/2023]
Abstract
Retinoic acid is generated from retinol (vitamin A) by the sequential actions of two different classes of enzymes, retinol dehydrogenases and retinal dehydrogenases. Several enzymes implicated in this process have been identified and characterized in vitro. However, our understanding of the cell biological function and regulation of this process is limited. To get further knowledge regarding the regulation of RA biosynthesis, we have determined possible regulatory mechanisms at the transcriptional and post-transcriptional levels for the prototypic microsomal retinol dehydrogenase cis-retinol/androgen dehydrogenase 1 (CRAD1). We note that the expression and stability of the enzyme are only moderately controlled by the retinoid status. Instead, we find that the cytosolic tail dramatically affects the activity of the enzyme, and we have mapped the structural elements required for ER retention and in vivo functional activity, respectively. Although inactive tail-deletion mutants display an abnormal subcellular localization, restoration of ER localization per se is not sufficient for enzymatic activity suggesting that additional trans-acting components interacting with, or modifying, the cytosolic tail are required for controlling the activity of the enzyme in vivo.
Collapse
Affiliation(s)
- Martin Lidén
- Ludwig Institute for Cancer Research, Stockholm Branch, Box 240, S-17177 Stockholm, Sweden
| | | | | |
Collapse
|
11
|
Lidén M, Eriksson U. Development of a versatile reporter assay for studies of retinol uptake and metabolism in vivo. Exp Cell Res 2005; 310:401-8. [PMID: 16150442 DOI: 10.1016/j.yexcr.2005.08.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2005] [Revised: 08/04/2005] [Accepted: 08/08/2005] [Indexed: 11/17/2022]
Abstract
The two isomers of retinoic acid (RA), all-trans RA and 9-cis RA, are produced in several tissues in order to allow specific control of target gene transcription. Given the high potency of these receptor ligands, it seems likely that the cellular uptake and metabolic activation of the precursor, retinol (vitamin A), should be a highly regulated process. Several retinol dehydrogenases and components involved in the downstream events have been identified and partially characterized. However, less is known about the cellular uptake of retinol, and the isomerase activity giving rise to the 9-cis and 11-cis branches of the pathway. In this work, we show that the 9-cis RA biosynthesis pathway can be fully reconstituted in cultured HEK293A cells expressing a reporter system, including an endogenous isomerase activity converting all-trans retinol into 9-cis retinol. This assay allows for functional studies of known components, as well as screening for yet unidentified genes involved in the pathway. In addition to free all-trans retinol, we find that these cells can take up retinol from plasma retinol binding protein (RBP) by a mechanism that can be efficiently inhibited by blocking antibodies, suggesting that the uptake may involve a cellular receptor. We also demonstrate that overexpression of CRBPI can drive the accumulation of intracellular retinol from unbound retinol added to the medium. Thus, this versatile cellular assay can be used to study several aspects of retinol uptake and metabolism in vivo.
Collapse
Affiliation(s)
- Martin Lidén
- Ludwig Institute for Cancer Research, Stockholm Branch, Box 240, S-171 77 Stockholm, Sweden
| | | |
Collapse
|
12
|
Zhang M, Hu P, Napoli JL. Elements in the N-terminal signaling sequence that determine cytosolic topology of short-chain dehydrogenases/reductases. Studies with retinol dehydrogenase type 1 and cis-retinol/androgen dehydrogenase type 1. J Biol Chem 2004; 279:51482-9. [PMID: 15355969 DOI: 10.1074/jbc.m409051200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
High affinity, retinoid-specific binding proteins chaperone retinoids to manage their transport and metabolism. Proposing mechanisms of retinoid transfer between these binding proteins and membrane-associated retinoid-metabolizing enzymes requires insight into enzyme topology. We therefore determined the topology of mouse retinol dehydrogenase type 1 (Rdh1) and cis-retinoid androgen dehydrogenase type 1 (Crad1) in the endoplasmic reticulum of intact mammalian cells. The properties of Rdh1 were compared with a chimera with a luminal signaling sequence (11beta-hydroxysteroid dehydrogenase (11beta-HSD1)(1-41)/Rdh1(23-317); the green fluorescent protein (GFP) fusion proteins Rdh1(1-22)/GFP, Crad1(1-22)/GFP, and 11beta-HSD1(1-41)/GFP; and signaling sequence charge difference mutants using confocal immunofluorescence, antibody access, proteinase K sensitivity, and deglycosylation assays. An N-terminal signaling sequence of 22 residues, consisting of a hydrophobic helix ending in a net positive charge, anchors Rdh1 and Crad1 in the endoplasmic reticulum facing the cytoplasm. Mutating arginine to glutamine in the signaling sequence did not affect topology. Inserting one or two arginine residues near the N terminus of the signaling sequence caused 28-95% inversion from cytoplasmic to luminal, depending on the net positive charge remaining at the C terminus of the signaling sequence; e.g. the mutant L3R,L5R,R16Q,R19Q,R21Q faced the lumen. Experiments with N- and C-terminal epitope-tagged Rdh1 and molecular modeling indicated that a hydrophobic helix-turn-helix near the C terminus of Rdh1 (residues 289-311) projects into the cytoplasm. These data provide insight into the features necessary to orient type III (reverse signal-anchor) proteins and demonstrate that Rdh1, Crad1, and other short-chain dehydrogenases/reductases, which share similar N-terminal signaling sequences such as human Rdh5 and mouse Rdh4, orient with their catalytic domains facing the cytoplasm.
Collapse
Affiliation(s)
- Min Zhang
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, California 94720-3104, USA
| | | | | |
Collapse
|
13
|
Lidén M, Tryggvason K, Eriksson U. Structure and function of retinol dehydrogenases of the short chain dehydrogenase/reductase family. Mol Aspects Med 2004; 24:403-9. [PMID: 14585311 DOI: 10.1016/s0098-2997(03)00036-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
All-trans-retinol is the common precursor of the active retinoids 11-cis-retinal, all-trans-retinoic acid (atRA) and 9-cis-retinoic acid (9cRA). Genetic and biochemical data supports an important role of the microsomal members of the short chain dehydrogenases/reductases (SDRs) in the first oxidative conversion of retinol into retinal. Several retinol dehydrogenases of this family have been reported in recent years. However, the structural and functional data on these enzymes is limited. The prototypic enzyme RDH5 and the related enzyme CRAD1 have been shown to face the lumen of the endoplasmic reticulum (ER), suggesting a compartmentalized synthesis of retinal. This is a matter of debate as a related enzyme has been proposed to have the opposite membrane topology. Recent data indicates that RDH5, and presumably other members of the SDRs, occur as functional homodimers, and need to interact with other proteins for proper intracellular localization and catalytic activity. Further analyses on the compartmentalization, membrane topology, and functional properties of microsomal retinol dehydrogenases, will give important clues about how retinoids are processed.
Collapse
Affiliation(s)
- Martin Lidén
- Ludwig Institute for Cancer Research, Stockholm Branch, Box 240, S-171 77 Stockholm, Sweden
| | | | | |
Collapse
|
14
|
Belyaeva OV, Stetsenko AV, Nelson P, Kedishvili NY. Properties of Short-Chain Dehydrogenase/Reductase RalR1: Characterization of Purified Enzyme, Its Orientation in the Microsomal Membrane, and Distribution in Human Tissues and Cell Lines. Biochemistry 2003; 42:14838-45. [PMID: 14674758 DOI: 10.1021/bi035288u] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Recently, we reported the first biochemical characterization of a novel member of the short-chain dehydrogenase/reductase superfamily, retinal reductase 1 (RalR1) (Kedishvili et al. (2002) J. Biol. Chem. 277, 28909-28915). In the present study, we purified the recombinant enzyme from the microsomal membranes of insect Sf9 cells, determined its catalytic efficiency for the reduction of retinal and the oxidation of retinol, established its transmembrane topology, and examined the distribution of RalR1 in human tissues and cell lines. Purified RalR1-His(6) exhibited the apparent K(m) values for all-trans-retinal and all-trans-retinol of 0.12 and 0.6 microM, respectively. The catalytic efficiency (k(cat)/K(m)) for the reduction of all-trans-retinal (150,000 min(-1) mM(-1)) was 8-fold higher than that for the oxidation of all-trans-retinol (18,000 min(-1) mM(-1)). Protease protection assays and site-directed mutagenesis suggested that the enzyme is anchored in the membrane by the N-terminal signal-anchor domain, with the majority of the polypeptide chain located on the cytosolic side of the membrane. An important feature that prevented the translocation of RalR1 across the membrane was the positively charged R(25)K motif flanking the N-terminal signal-anchor. The cytosolic orientation of RalR1 suggested that, in intact cells, the enzyme would function predominantly as a reductase. Western blot analysis revealed that RalR1 is expressed in a wide variety of normal human tissues and cancer cell lines. The expression pattern and the high catalytic efficiency of RalR1 are consistent with the hypothesis that RalR1 contributes to the reduction of retinal in various human tissues.
Collapse
Affiliation(s)
- Olga V Belyaeva
- Division of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, 64110, USA
| | | | | | | |
Collapse
|
15
|
Belyaeva OV, Chetyrkin SV, Kedishvili NY. Characterization of truncated mutants of human microsomal short-chain dehydrogenase/reductase RoDH-4. Chem Biol Interact 2003; 143-144:279-87. [PMID: 12604214 DOI: 10.1016/s0009-2797(02)00181-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Human NAD(+)-dependent microsomal short-chain dehydrogenase/reductase RoDH-4 oxidizes all-trans-retinol, 13-cis-retinol and 3alpha-hydroxysteroids to corresponding retinaldehydes and 3-ketones. RoDH-4 behaves as an integral membrane protein, but its topology in the membrane is not known. Analysis of RoDH-4 polypeptide using algorithms for secondary structure predictions suggests that RoDH-4 contains four potential membrane-spanning domains: the N-terminal, the C-terminal, and the two central hydrophobic segments. To determine the role of each segment in association of RoDH-4 with the membrane, we prepared several expression constructs coding for truncated RoDH-4 polypeptides that lacked the putative membrane-spanning domains and expressed them in insect Sf9 cells using the Baculovirus system. Association of truncated RoDH-4 constructs with the microsomal membranes was analyzed by alkaline extraction and floatation in sucrose gradient. Catalytic activity of truncated RoDH-4 constructs was assayed using the 3alpha-hydroxysteroid androsterone as substrate. Truncated RoDH-4 that lacked the first thirteen amino acids of the N-terminal segment was partially active and exhibited the apparent K(m) value for androsterone similar to that of the wild-type enzyme. Removal of 23 N-terminal hydrophobic amino acids resulted in significant loss of activity and a 14-fold increase in the apparent K(m) value. Removal of the C-terminal 27 amino acid segment resulted in a approximately 600-fold increase in the apparent K(m) value. Each truncated mutant behaved as an integral membrane protein. Furthermore, protein that lacked all four hydrophobic segments remained associated with the membrane. Thus, the N-terminal and the C-terminal ends are both important for RoDH-4 activity and the removal of the putative transmembrane segments does not convert RoDH-4 into a soluble protein, suggesting additional sites of membrane interaction.
Collapse
Affiliation(s)
- Olga V Belyaeva
- School of Biological Sciences, Division of Molecular Biology and Biochemistry, University of Missouri-Kansas City, 5007 Rockhill Road, 103 BSB, Kansas City, MO 64110, USA
| | | | | |
Collapse
|
16
|
Lidén M, Romert A, Tryggvason K, Persson B, Eriksson U. Biochemical defects in 11-cis-retinol dehydrogenase mutants associated with fundus albipunctatus. J Biol Chem 2001; 276:49251-7. [PMID: 11675386 DOI: 10.1074/jbc.m107337200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mutations in the gene encoding 11-cis-retinol dehydrogenase (RDH5; EC ) are associated with fundus albipunctatus, an autosomal recessive eye disease characterized by stationary night blindness and accumulation of white spots in the retina. In addition, some mutated alleles are associated with development of cone dystrophy, especially in elderly patients. The numbers of identified RDH5 mutations linked to fundus albipunctatus have increased considerably during recent years. In this work, we have characterized the biochemical and cell biological properties of 11 mutants of RDH5 to understand the molecular pathology of the disease. All RDH5 mutants showed decreased protein stability and subcellular mislocalization and, in most cases, loss of enzymatic activity in vitro and in vivo. Surprisingly, mutant A294P displays significant enzymatic activity. Cross-linking studies and molecular modeling showed that RDH5 is dimeric, and co-expression analyses of wild-type and mutated alleles showed that the mutated enzymes, in a trans-dominant-negative manner, influenced the in vivo enzymatic properties of functional variants of the enzyme, particularly the A294P mutant. Thus, under certain conditions, nonfunctional alleles act in a dominant-negative way on functional but relatively unstable mutated alleles. However, in heterozygous individuals carrying one wild-type allele, the disease is recessive, probably due to the stability of the wild-type enzyme.
Collapse
Affiliation(s)
- M Lidén
- Ludwig Institute for Cancer Research, Stockholm Branch, Box 240, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | | | | | | | | |
Collapse
|