1
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Steinhoff JS, Wagner C, Dähnhardt HE, Košić K, Meng Y, Taschler U, Pajed L, Yang N, Wulff S, Kiefer MF, Petricek KM, Flores RE, Li C, Dittrich S, Sommerfeld M, Guillou H, Henze A, Raila J, Wowro SJ, Schoiswohl G, Lass A, Schupp M. Adipocyte HSL is required for maintaining circulating vitamin A and RBP4 levels during fasting. EMBO Rep 2024; 25:2878-2895. [PMID: 38769419 PMCID: PMC11239848 DOI: 10.1038/s44319-024-00158-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 04/19/2024] [Accepted: 04/30/2024] [Indexed: 05/22/2024] Open
Abstract
Vitamin A (retinol) is distributed via the blood bound to its specific carrier protein, retinol-binding protein 4 (RBP4). Retinol-loaded RBP4 is secreted into the circulation exclusively from hepatocytes, thereby mobilizing hepatic retinoid stores that represent the major vitamin A reserves in the body. The relevance of extrahepatic retinoid stores for circulating retinol and RBP4 levels that are usually kept within narrow physiological limits is unknown. Here, we show that fasting affects retinoid mobilization in a tissue-specific manner, and that hormone-sensitive lipase (HSL) in adipose tissue is required to maintain serum concentrations of retinol and RBP4 during fasting in mice. We found that extracellular retinol-free apo-RBP4 induces retinol release by adipocytes in an HSL-dependent manner. Consistently, global or adipocyte-specific HSL deficiency leads to an accumulation of retinoids in adipose tissue and a drop of serum retinol and RBP4 during fasting, which affects retinoid-responsive gene expression in eye and kidney and lowers renal retinoid content. These findings establish a novel crosstalk between liver and adipose tissue retinoid stores for the maintenance of systemic vitamin A homeostasis during fasting.
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Affiliation(s)
- Julia S Steinhoff
- Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Pharmacology, Max Rubner Center (MRC) for Cardiovascular-Metabolic-Renal Research, Berlin, Germany
| | - Carina Wagner
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - Henriette E Dähnhardt
- Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Pharmacology, Max Rubner Center (MRC) for Cardiovascular-Metabolic-Renal Research, Berlin, Germany
| | - Kristina Košić
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - Yueming Meng
- Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Pharmacology, Max Rubner Center (MRC) for Cardiovascular-Metabolic-Renal Research, Berlin, Germany
| | - Ulrike Taschler
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - Laura Pajed
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - Na Yang
- Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Pharmacology, Max Rubner Center (MRC) for Cardiovascular-Metabolic-Renal Research, Berlin, Germany
| | - Sascha Wulff
- Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Pharmacology, Max Rubner Center (MRC) for Cardiovascular-Metabolic-Renal Research, Berlin, Germany
| | - Marie F Kiefer
- Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Pharmacology, Max Rubner Center (MRC) for Cardiovascular-Metabolic-Renal Research, Berlin, Germany
| | - Konstantin M Petricek
- Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Pharmacology, Max Rubner Center (MRC) for Cardiovascular-Metabolic-Renal Research, Berlin, Germany
| | - Roberto E Flores
- Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Pharmacology, Max Rubner Center (MRC) for Cardiovascular-Metabolic-Renal Research, Berlin, Germany
| | - Chen Li
- Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Pharmacology, Max Rubner Center (MRC) for Cardiovascular-Metabolic-Renal Research, Berlin, Germany
| | - Sarah Dittrich
- Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Pharmacology, Max Rubner Center (MRC) for Cardiovascular-Metabolic-Renal Research, Berlin, Germany
| | - Manuela Sommerfeld
- Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Pharmacology, Max Rubner Center (MRC) for Cardiovascular-Metabolic-Renal Research, Berlin, Germany
| | - Hervé Guillou
- Toxalim (Research Center in Food Toxicology), INRAE, ENVT, INP- PURPAN, UMR 1331, UPS, Université de Toulouse, Toulouse, France
| | - Andrea Henze
- Martin Luther University Halle-Wittenberg, Institute of Agricultural and Nutritional Sciences, Halle, Germany
- Junior Research Group ProAID, Institute of Nutritional Science, University of Potsdam, Nuthetal, Germany
| | - Jens Raila
- Department of Physiology and Pathophysiology, Institute of Nutritional Science, University of Potsdam, Nuthetal, Germany
| | - Sylvia J Wowro
- Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Pharmacology, Max Rubner Center (MRC) for Cardiovascular-Metabolic-Renal Research, Berlin, Germany
| | - Gabriele Schoiswohl
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Achim Lass
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria.
- BioTechMed-Graz, Graz, Austria.
| | - Michael Schupp
- Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Pharmacology, Max Rubner Center (MRC) for Cardiovascular-Metabolic-Renal Research, Berlin, Germany.
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2
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Zhang S, Wang Y, Mao D, Wang Y, Zhang H, Pan Y, Wang Y, Teng S, Huang P. Current trends of clinical trials involving CRISPR/Cas systems. Front Med (Lausanne) 2023; 10:1292452. [PMID: 38020120 PMCID: PMC10666174 DOI: 10.3389/fmed.2023.1292452] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 10/25/2023] [Indexed: 12/01/2023] Open
Abstract
The CRISPR/Cas9 system is a powerful genome editing tool that has made enormous impacts on next-generation molecular diagnostics and therapeutics, especially for genetic disorders that traditional therapies cannot cure. Currently, CRISPR-based gene editing is widely applied in basic, preclinical, and clinical studies. In this review, we attempt to identify trends in clinical studies involving CRISPR techniques to gain insights into the improvement and contribution of CRISPR/Cas technologies compared to traditional modified modalities. The review of clinical trials is focused on the applications of the CRISPR/Cas systems in the treatment of cancer, hematological, endocrine, and immune system diseases, as well as in diagnostics. The scientific basis underlined is analyzed. In addition, the challenges of CRISPR application in disease therapies and recent advances that expand and improve CRISPR applications in precision medicine are discussed.
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Affiliation(s)
- Songyang Zhang
- The Key Laboratory of Pathobiology, Ministry of Education, Norman Bethune College of Medicine, Jilin University, Changchun, China
| | - Yidi Wang
- The Third Affiliated Hospital of Jilin University, Changchun, China
| | - Dezhi Mao
- The Third Affiliated Hospital of Jilin University, Changchun, China
| | - Yue Wang
- The Second Affiliated Hospital of Jilin University, Changchun, China
| | - Hong Zhang
- The Third Affiliated Hospital of Jilin University, Changchun, China
| | - Yihan Pan
- The Second Affiliated Hospital of Jilin University, Changchun, China
| | - Yuezeng Wang
- The Key Laboratory of Pathobiology, Ministry of Education, Norman Bethune College of Medicine, Jilin University, Changchun, China
| | - Shuzhi Teng
- The Key Laboratory of Pathobiology, Ministry of Education, Norman Bethune College of Medicine, Jilin University, Changchun, China
| | - Ping Huang
- The Key Laboratory of Pathobiology, Ministry of Education, Norman Bethune College of Medicine, Jilin University, Changchun, China
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3
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Yadav AS, Isoherranen N, Rubinow KB. Vitamin A homeostasis and cardiometabolic disease in humans: lost in translation? J Mol Endocrinol 2022; 69:R95-R108. [PMID: 35900842 PMCID: PMC9534526 DOI: 10.1530/jme-22-0078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 07/27/2022] [Indexed: 11/08/2022]
Abstract
Vitamin A (retinol) is an essential, fat-soluble vitamin that plays critical roles in embryonic development, vision, immunity, and reproduction. Severe vitamin A deficiency results in profound embryonic dysgenesis, blindness, and infertility. The roles of bioactive vitamin A metabolites in regulating cell proliferation, cellular differentiation, and immune cell function form the basis of their clinical use in the treatment of dermatologic conditions and hematologic malignancies. Increasingly, vitamin A also has been recognized to play important roles in cardiometabolic health, including the regulation of adipogenesis, energy partitioning, and lipoprotein metabolism. While these roles are strongly supported by animal and in vitro studies, they remain poorly understood in human physiology and disease. This review briefly introduces vitamin A biology and presents the key preclinical data that have generated interest in vitamin A as a mediator of cardiometabolic health. The review also summarizes clinical studies performed to date, highlighting the limitations of many of these studies and the ongoing controversies in the field. Finally, additional perspectives are suggested that may help position vitamin A metabolism within a broader biological context and thereby contribute to enhanced understanding of vitamin A's complex roles in clinical cardiometabolic disease.
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Affiliation(s)
- Aprajita S Yadav
- Department of Pharmaceutics, School of Pharmacy, University of Washington, Seattle, Washington, USA
| | - Nina Isoherranen
- Department of Pharmaceutics, School of Pharmacy, University of Washington, Seattle, Washington, USA
| | - Katya B Rubinow
- Department of Pharmaceutics, School of Pharmacy, University of Washington, Seattle, Washington, USA
- Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, University of Washington, Seattle, Washington, USA
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4
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Sanguinetti C, Minniti M, Susini V, Caponi L, Panichella G, Castiglione V, Aimo A, Emdin M, Vergaro G, Franzini M. The Journey of Human Transthyretin: Synthesis, Structure Stability, and Catabolism. Biomedicines 2022; 10:biomedicines10081906. [PMID: 36009453 PMCID: PMC9405911 DOI: 10.3390/biomedicines10081906] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 08/03/2022] [Accepted: 08/04/2022] [Indexed: 12/19/2022] Open
Abstract
Transthyretin (TTR) is a homotetrameric protein mainly synthesised by the liver and the choroid plexus whose function is to carry the thyroid hormone thyroxine and the retinol-binding protein bound to retinol in plasma and cerebrospinal fluid. When the stability of the tetrameric structure is lost, it breaks down, paving the way for the aggregation of TTR monomers into insoluble fibrils leading to transthyretin (ATTR) amyloidosis, a progressive disorder mainly affecting the heart and nervous system. Several TTR gene mutations have been characterised as destabilisers of TTR structure and are associated with hereditary forms of ATTR amyloidosis. The reason why also the wild-type TTR is intrinsically amyloidogenic in some subjects is largely unknown. The aim of the review is to give an overview of the TTR biological life cycle which is largely unknown. For this purpose, the current knowledge on TTR physiological metabolism, from its synthesis to its catabolism, is described. Furthermore, a large section of the review is dedicated to examining in depth the role of mutations and physiological ligands on the stability of TTR tetramers.
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Affiliation(s)
- Chiara Sanguinetti
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, Italy
| | - Marianna Minniti
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, Italy
| | - Vanessa Susini
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, Italy
| | - Laura Caponi
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, Italy
| | - Giorgia Panichella
- “Health Science” Interdisciplinary Research Center, Scuola Superiore Sant’Anna, 56127 Pisa, Italy
| | - Vincenzo Castiglione
- “Health Science” Interdisciplinary Research Center, Scuola Superiore Sant’Anna, 56127 Pisa, Italy
| | - Alberto Aimo
- “Health Science” Interdisciplinary Research Center, Scuola Superiore Sant’Anna, 56127 Pisa, Italy
- Cardiology Division, Fondazione Toscana Gabriele Monasterio, 56124 Pisa, Italy
| | - Michele Emdin
- “Health Science” Interdisciplinary Research Center, Scuola Superiore Sant’Anna, 56127 Pisa, Italy
- Cardiology Division, Fondazione Toscana Gabriele Monasterio, 56124 Pisa, Italy
| | - Giuseppe Vergaro
- “Health Science” Interdisciplinary Research Center, Scuola Superiore Sant’Anna, 56127 Pisa, Italy
- Cardiology Division, Fondazione Toscana Gabriele Monasterio, 56124 Pisa, Italy
| | - Maria Franzini
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, Italy
- Correspondence:
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5
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O’Connor C, Varshosaz P, Moise AR. Mechanisms of Feedback Regulation of Vitamin A Metabolism. Nutrients 2022; 14:nu14061312. [PMID: 35334970 PMCID: PMC8950952 DOI: 10.3390/nu14061312] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 03/15/2022] [Accepted: 03/17/2022] [Indexed: 02/06/2023] Open
Abstract
Vitamin A is an essential nutrient required throughout life. Through its various metabolites, vitamin A sustains fetal development, immunity, vision, and the maintenance, regulation, and repair of adult tissues. Abnormal tissue levels of the vitamin A metabolite, retinoic acid, can result in detrimental effects which can include congenital defects, immune deficiencies, proliferative defects, and toxicity. For this reason, intricate feedback mechanisms have evolved to allow tissues to generate appropriate levels of active retinoid metabolites despite variations in the level and format, or in the absorption and conversion efficiency of dietary vitamin A precursors. Here, we review basic mechanisms that govern vitamin A signaling and metabolism, and we focus on retinoic acid-controlled feedback mechanisms that contribute to vitamin A homeostasis. Several approaches to investigate mechanistic details of the vitamin A homeostatic regulation using genomic, gene editing, and chromatin capture technologies are also discussed.
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Affiliation(s)
- Catherine O’Connor
- MD Program, Northern Ontario School of Medicine, 317-MSE Bldg., 935 Ramsey Lake Rd., Sudbury, ON P3E 2C6, Canada;
| | - Parisa Varshosaz
- Biology and Biomolecular Sciences Ph.D. Program, Northern Ontario School of Medicine, Laurentian University, Sudbury, ON P3E 2C6, Canada;
| | - Alexander R. Moise
- Medical Sciences Division, Northern Ontario School of Medicine, 317-MSE Bldg., 935 Ramsey Lake Rd., Sudbury, ON P3E 2C6, Canada
- Department of Chemistry and Biochemistry, Biology and Biomolecular Sciences Program, Laurentian University, Sudbury, ON P3E 2C6, Canada
- Correspondence: ; Tel.: +1-705-662-7253
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6
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Steinhoff JS, Lass A, Schupp M. Retinoid Homeostasis and Beyond: How Retinol Binding Protein 4 Contributes to Health and Disease. Nutrients 2022; 14:1236. [PMID: 35334893 PMCID: PMC8951293 DOI: 10.3390/nu14061236] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 03/09/2022] [Accepted: 03/11/2022] [Indexed: 02/06/2023] Open
Abstract
Retinol binding protein 4 (RBP4) is the specific transport protein of the lipophilic vitamin A, retinol, in blood. Circulating RBP4 originates from the liver. It is secreted by hepatocytes after it has been loaded with retinol and binding to transthyretin (TTR). TTR association prevents renal filtration due to the formation of a higher molecular weight complex. In the circulation, RBP4 binds to specific membrane receptors, thereby delivering retinol to target cells, rendering liver-secreted RBP4 the major mechanism to distribute hepatic vitamin A stores to extrahepatic tissues. In particular, binding of RBP4 to 'stimulated by retinoic acid 6' (STRA6) is required to balance tissue retinoid responses in a highly homeostatic manner. Consequently, defects/mutations in RBP4 can cause a variety of conditions and diseases due to dysregulated retinoid homeostasis and cover embryonic development, vision, metabolism, and cardiovascular diseases. Aside from the effects related to retinol transport, non-canonical functions of RBP4 have also been reported. In this review, we summarize the current knowledge on the regulation and function of RBP4 in health and disease derived from murine models and human mutations.
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Affiliation(s)
- Julia S. Steinhoff
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Pharmacology, Cardiovascular Metabolic Renal (CMR)-Research Center, 10115 Berlin, Germany;
| | - Achim Lass
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Heinrichstraße 31/II, A-8010 Graz, Austria;
- Field of Excellence BioHealth, University of Graz, Heinrichstraße 31/II, A-8010 Graz, Austria
| | - Michael Schupp
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Pharmacology, Cardiovascular Metabolic Renal (CMR)-Research Center, 10115 Berlin, Germany;
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Discovery of phenylpyrrolidine derivatives as a novel class of retinol binding protein 4 (RBP4) reducers. Bioorg Med Chem 2021; 54:116553. [PMID: 34953340 DOI: 10.1016/j.bmc.2021.116553] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 11/25/2021] [Accepted: 11/29/2021] [Indexed: 12/23/2022]
Abstract
Retinol-binding protein 4 (RBP4) is a potential drug target for metabolic and ophthalmologic diseases. A high-throughput screening of our compound library has identified a small-molecule RBP4 reducer 7a, as a hit compound. Aiming to provide a suitable tool for investigating the pharmacological effects of RBP4 reducers, we conducted a structure-activity relationship study of 7a. Exploration of the aryl head, oxazole core, and propanoic acid tail of 7a resulted in the discovery of novel, potent, and orally available phenylpyrrolidine derivatives 43b and 43c. Compound 43b had a potent and long-lasting blood RBP4-level-reducing effect when orally administered to mice at a dose as low as 0.3 mg/kg.
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8
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Martin Ask N, Leung M, Radhakrishnan R, Lobo GP. Vitamin A Transporters in Visual Function: A Mini Review on Membrane Receptors for Dietary Vitamin A Uptake, Storage, and Transport to the Eye. Nutrients 2021; 13:nu13113987. [PMID: 34836244 PMCID: PMC8620617 DOI: 10.3390/nu13113987] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 11/04/2021] [Accepted: 11/07/2021] [Indexed: 11/23/2022] Open
Abstract
Vitamins are essential compounds obtained through diet that are necessary for normal development and function in an organism. One of the most important vitamins for human physiology is vitamin A, a group of retinoid compounds and carotenoids, which generally function as a mediator for cell growth, differentiation, immunity, and embryonic development, as well as serving as a key component in the phototransduction cycle in the vertebrate retina. For humans, vitamin A is obtained through the diet, where provitamin A carotenoids such as β-carotene from plants or preformed vitamin A such as retinyl esters from animal sources are absorbed into the body via the small intestine and converted into all-trans retinol within the intestinal enterocytes. Specifically, once absorbed, carotenoids are cleaved by carotenoid cleavage oxygenases (CCOs), such as Beta-carotene 15,15’-monooxygenase (BCO1), to produce all-trans retinal that subsequently gets converted into all-trans retinol. CRBP2 bound retinol is then converted into retinyl esters (REs) by the enzyme lecithin retinol acyltransferase (LRAT) in the endoplasmic reticulum, which is then packaged into chylomicrons and sent into the bloodstream for storage in hepatic stellate cells in the liver or for functional use in peripheral tissues such as the retina. All-trans retinol also travels through the bloodstream bound to retinol binding protein 4 (RBP4), where it enters cells with the assistance of the transmembrane transporters, stimulated by retinoic acid 6 (STRA6) in peripheral tissues or retinol binding protein 4 receptor 2 (RBPR2) in systemic tissues (e.g., in the retina and the liver, respectively). Much is known about the intake, metabolism, storage, and function of vitamin A compounds, especially with regard to its impact on eye development and visual function in the retinoid cycle. However, there is much to learn about the role of vitamin A as a transcription factor in development and cell growth, as well as how peripheral cells signal hepatocytes to secrete all-trans retinol into the blood for peripheral cell use. This article aims to review literature regarding the major known pathways of vitamin A intake from dietary sources into hepatocytes, vitamin A excretion by hepatocytes, as well as vitamin A usage within the retinoid cycle in the RPE and retina to provide insight on future directions of novel membrane transporters for vitamin A in retinal cell physiology and visual function.
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Steinhoff JS, Lass A, Schupp M. Biological Functions of RBP4 and Its Relevance for Human Diseases. Front Physiol 2021; 12:659977. [PMID: 33790810 PMCID: PMC8006376 DOI: 10.3389/fphys.2021.659977] [Citation(s) in RCA: 83] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 02/22/2021] [Indexed: 12/13/2022] Open
Abstract
Retinol binding protein 4 (RBP4) is a member of the lipocalin family and the major transport protein of the hydrophobic molecule retinol, also known as vitamin A, in the circulation. Expression of RBP4 is highest in the liver, where most of the body’s vitamin A reserves are stored as retinyl esters. For the mobilization of vitamin A from the liver, retinyl esters are hydrolyzed to retinol, which then binds to RBP4 in the hepatocyte. After associating with transthyretin (TTR), the retinol/RBP4/TTR complex is released into the bloodstream and delivers retinol to tissues via binding to specific membrane receptors. So far, two distinct RBP4 receptors have been identified that mediate the uptake of retinol across the cell membrane and, under specific conditions, bi-directional retinol transport. Although most of RBP4’s actions depend on its role in retinoid homeostasis, functions independent of retinol transport have been described. In this review, we summarize and discuss the recent findings on the structure, regulation, and functions of RBP4 and lay out the biological relevance of this lipocalin for human diseases.
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Affiliation(s)
- Julia S Steinhoff
- Institute of Pharmacology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Achim Lass
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria.,BioTechMed-Graz, Graz, Austria
| | - Michael Schupp
- Institute of Pharmacology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
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10
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Bezerra F, Saraiva MJ, Almeida MR. Modulation of the Mechanisms Driving Transthyretin Amyloidosis. Front Mol Neurosci 2020; 13:592644. [PMID: 33362465 PMCID: PMC7759661 DOI: 10.3389/fnmol.2020.592644] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 11/18/2020] [Indexed: 12/19/2022] Open
Abstract
Transthyretin (TTR) amyloidoses are systemic diseases associated with TTR aggregation and extracellular deposition in tissues as amyloid. The most frequent and severe forms of the disease are hereditary and associated with amino acid substitutions in the protein due to single point mutations in the TTR gene (ATTRv amyloidosis). However, the wild type TTR (TTR wt) has an intrinsic amyloidogenic potential that, in particular altered physiologic conditions and aging, leads to TTR aggregation in people over 80 years old being responsible for the non-hereditary ATTRwt amyloidosis. In normal physiologic conditions TTR wt occurs as a tetramer of identical subunits forming a central hydrophobic channel where small molecules can bind as is the case of the natural ligand thyroxine (T4). However, the TTR amyloidogenic variants present decreased stability, and in particular conditions, dissociate into partially misfolded monomers that aggregate and polymerize as amyloid fibrils. Therefore, therapeutic strategies for these amyloidoses may target different steps in the disease process such as decrease of variant TTR (TTRv) in plasma, stabilization of TTR, inhibition of TTR aggregation and polymerization or disruption of the preformed fibrils. While strategies aiming decrease of the mutated TTR involve mainly genetic approaches, either by liver transplant or the more recent technologies using specific oligonucleotides or silencing RNA, the other steps of the amyloidogenic cascade might be impaired by pharmacologic compounds, namely, TTR stabilizers, inhibitors of aggregation and amyloid disruptors. Modulation of different steps involved in the mechanism of ATTR amyloidosis and compounds proposed as pharmacologic agents to treat TTR amyloidosis will be reviewed and discussed.
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Affiliation(s)
- Filipa Bezerra
- Molecular Neurobiology Group, IBMC-Instituto de Biologia Molecular e Celular, i3S-Instituto de Investigação e Inovação em Saúde, Porto, Portugal.,Department of Molecular Biology, ICBAS-Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Maria João Saraiva
- Molecular Neurobiology Group, IBMC-Instituto de Biologia Molecular e Celular, i3S-Instituto de Investigação e Inovação em Saúde, Porto, Portugal.,Department of Molecular Biology, ICBAS-Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Maria Rosário Almeida
- Molecular Neurobiology Group, IBMC-Instituto de Biologia Molecular e Celular, i3S-Instituto de Investigação e Inovação em Saúde, Porto, Portugal.,Department of Molecular Biology, ICBAS-Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
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11
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Undiscovered Roles for Transthyretin: From a Transporter Protein to a New Therapeutic Target for Alzheimer's Disease. Int J Mol Sci 2020; 21:ijms21062075. [PMID: 32197355 PMCID: PMC7139926 DOI: 10.3390/ijms21062075] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 03/10/2020] [Accepted: 03/16/2020] [Indexed: 12/27/2022] Open
Abstract
Transthyretin (TTR), an homotetrameric protein mainly synthesized by the liver and the choroid plexus, and secreted into the blood and the cerebrospinal fluid, respectively, has been specially acknowledged for its functions as a transporter protein of thyroxine and retinol (the latter through binding to the retinol-binding protein), in these fluids. Still, this protein has managed to stay in the spotlight as it has been assigned new and varied functions. In this review, we cover knowledge on novel TTR functions and the cellular pathways involved, spanning from neuroprotection to vascular events, while emphasizing its involvement in Alzheimer’s disease (AD). We describe details of TTR as an amyloid binding protein and discuss its interaction with the amyloid Aβ peptides, and the proposed mechanisms underlying TTR neuroprotection in AD. We also present the importance of translating advances in the knowledge of the TTR neuroprotective role into drug discovery strategies focused on TTR as a new target in AD therapeutics.
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12
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Goel V, Gosselin NH, Jomphe C, Zhang X, Marier JF, Robbie GJ. Population Pharmacokinetic-Pharmacodynamic Model of Serum Transthyretin Following Patisiran Administration. Nucleic Acid Ther 2020; 30:143-152. [PMID: 32175804 DOI: 10.1089/nat.2019.0841] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Hereditary transthyretin-mediated amyloidosis is an inherited, rapidly progressive, life-threatening disease caused by mutated transthyretin (TTR) protein. Patisiran is a small interfering RNA (siRNA) formulated in a lipid nanoparticle that inhibits hepatic TTR protein synthesis by RNA interference. We have developed an indirect-response pharmacokinetic-pharmacodynamic model relating plasma siRNA (ALN-18328) levels to serum TTR reduction across five clinical studies. A sigmoidal function described this relationship, with estimated Hill coefficient of 0.548, and half maximal inhibitory concentration (IC50), IC80, and IC90 values of 9.45, 118.5, and 520.5 ng/mL, respectively. Following patisiran 0.3 mg/kg every 3 weeks (q3w), steady-state plasma ALN-18328 exposures were between IC80 and IC90, yielding average serum TTR reductions of 80%-90% from baseline. Covariate analysis indicated similar TTR reduction across evaluated intrinsic and extrinsic factors, obviating the need for dose adjustment. Modeling results support the recommended patisiran dosing schedule of 0.3 mg/kg q3w, with a maximum dose of 30 mg for patients weighing ≥100 kg.
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Affiliation(s)
- Varun Goel
- Alnylam Pharmaceuticals, Cambridge, Massachusetts, USA
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13
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Alshehri B, Pagnin M, Lee JY, Petratos S, Richardson SJ. The Role of Transthyretin in Oligodendrocyte Development. Sci Rep 2020; 10:4189. [PMID: 32144308 PMCID: PMC7060235 DOI: 10.1038/s41598-020-60699-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 02/14/2020] [Indexed: 01/23/2023] Open
Abstract
Transthyretin (TTR) is a protein that binds and distributes thyroid hormones (THs) in blood and cerebrospinal fluid. Previously, two reports identified TTR null mice as hypothyroid in the central nervous system (CNS). This prompted our investigations into developmentally regulated TH-dependent processes in brains of wildtype and TTR null mice. Despite logical expectations of a hypomyelinating phenotype in the CNS of TTR null mice, we observed a hypermyelination phenotype, synchronous with an increase in the density of oligodendrocytes in the corpus callosum and anterior commissure of TTR null mice during postnatal development. Furthermore, absence of TTR enhanced proliferation and migration of OPCs with decreased apoptosis. Neural stem cells (NSCs) isolated from the subventricular zone of TTR null mice at P21 revealed that the absence of TTR promoted NSC differentiation toward a glial lineage. Importantly, we identified TTR synthesis in OPCs, suggestive of an alternate biological function in these cells that may extend beyond an extracellular TH-distributor protein. The hypermyelination mechanism may involve increased pAKT (involved in oligodendrocyte maturation) in TTR null mice. Elucidating the regulatory role of TTR in NSC and OPC biology could lead to potential therapeutic strategies for the treatment of acquired demyelinating diseases.
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Affiliation(s)
- Bandar Alshehri
- School of Health and Biomedical Sciences, RMIT University, Bundoora, Victoria, 3083, Australia.,Faculty of Applied Medical Sciences, Najran University, Najran, Saudi Arabia
| | - Maurice Pagnin
- School of Health and Biomedical Sciences, RMIT University, Bundoora, Victoria, 3083, Australia
| | - Jae Young Lee
- Department of Neuroscience, Central Clinical School, Monash University, Prahran, Victoria, 3004, Australia.,ToolGen, Inc., Seoul, 08501, Korea
| | - Steven Petratos
- Department of Neuroscience, Central Clinical School, Monash University, Prahran, Victoria, 3004, Australia
| | - Samantha J Richardson
- School of Health and Biomedical Sciences, RMIT University, Bundoora, Victoria, 3083, Australia. .,School of Science, RMIT University, Bundoora, Victoria, 3083, Australia.
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14
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Haaker MW, Vaandrager AB, Helms JB. Retinoids in health and disease: A role for hepatic stellate cells in affecting retinoid levels. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1865:158674. [PMID: 32105672 DOI: 10.1016/j.bbalip.2020.158674] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 02/20/2020] [Accepted: 02/21/2020] [Indexed: 12/13/2022]
Abstract
Vitamin A (retinol) is important for normal growth, vision and reproduction. It has a role in the immune response and the development of metabolic syndrome. Most of the retinol present in the body is stored as retinyl esters within lipid droplets in hepatic stellate cells (HSCs). In case of liver damage, HSCs release large amounts of stored retinol, which is partially converted to retinoic acid (RA). This surge of RA can mediate the immune response and enhance the regeneration of the liver. If the damage persists activated HSCs change into myofibroblast-like cells producing extracellular matrix, which increases the chance of tumorigenesis to occur. RA has been shown to decrease proliferation and metastasis of hepatocellular carcinoma. The levels of RA and RA signaling are influenced by the possibility to esterify retinol towards retinyl esters. This suggests a complex regulation between different retinoids, with an important regulatory role for HSCs.
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Affiliation(s)
- Maya W Haaker
- Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
| | - Arie B Vaandrager
- Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
| | - J Bernd Helms
- Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands.
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15
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Zhang X, Goel V, Attarwala H, Sweetser MT, Clausen VA, Robbie GJ. Patisiran Pharmacokinetics, Pharmacodynamics, and Exposure-Response Analyses in the Phase 3 APOLLO Trial in Patients With Hereditary Transthyretin-Mediated (hATTR) Amyloidosis. J Clin Pharmacol 2020; 60:37-49. [PMID: 31322739 PMCID: PMC6972979 DOI: 10.1002/jcph.1480] [Citation(s) in RCA: 80] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 06/12/2019] [Indexed: 12/26/2022]
Abstract
Hereditary transthyretin-mediated (hATTR) amyloidosis is an inherited, rapidly progressive, life-threatening disease caused by deposition of abnormal transthyretin protein. Patisiran is an RNA interference therapeutic comprising a novel, small interfering ribonucleic acid (ALN-18328) formulated in a lipid nanoparticle targeted to inhibit hepatic transthyretin protein synthesis. The lipid nanoparticle also contains 2 novel lipid excipients (DLin-MC3-DMA and PEG2000 -C-DMG). Here we report patisiran pharmacokinetics (PK), pharmacodynamics (PD), and exposure-response analyses from the phase 3 APOLLO trial, in which patients with hATTR amyloidosis with polyneuropathy were randomized 2:1 to receive patisiran 0.3 mg/kg or placebo intravenously every 3 weeks over 18 months. In patisiran-treated patients, mean maximum reduction in serum transthyretin level from baseline was 87.8%. Patisiran PK exposure was stable following chronic dosing. There were no meaningful differences in PK exposure, serum transthyretin reduction, and efficacy (change from baseline in modified Neuropathy Impairment Score+7) across all subgroups analyzed (age, sex, race, body weight, genotype status of valine-to-methionine mutation at position 30 [V30M] and non-V30M, prior use of tetramer stabilizers, mild/moderate renal impairment, and mild hepatic impairment). transthyretin reduction and efficacy were similar across the interpatient PK exposure range for ALN-18328. There was no trend in the incidence of adverse events or serious adverse events across the interpatient PK exposure range for all 3 analytes. Incidence of antidrug antibodies was low (3.4%) and transient, with no impact on PK, PD, efficacy, or safety. The patisiran dosing regimen of 0.3 mg/kg every 3 weeks is appropriate for all patients with hATTR amyloidosis.
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16
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Arvanitis M, Koch CM, Chan GG, Torres-Arancivia C, LaValley MP, Jacobson DR, Berk JL, Connors LH, Ruberg FL. Identification of Transthyretin Cardiac Amyloidosis Using Serum Retinol-Binding Protein 4 and a Clinical Prediction Model. JAMA Cardiol 2019; 2:305-313. [PMID: 28196196 DOI: 10.1001/jamacardio.2016.5864] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Importance Transthyretin cardiac amyloidosis (ATTR) is an underrecognized cause of heart failure (HF) in older individuals, owing in part to difficulty in diagnosis. ATTR can result from substitution of valine for isoleucine at codon 122 of the transthyretin (TTR) gene (V122I), present in 3.43% of African American individuals. Objective To examine whether serum retinol-binding protein 4 (RBP4), an endogenous TTR ligand, could be used as a diagnostic test for ATTR V122I amyloidosis. Design, Setting, and Participants In this combined prospective and retrospective cohort study performed at a tertiary care referral center, 50 African American patients 60 years or older with nonamyloid HF and cardiac wall thickening prospectively genotyped from September 1, 2014, through December 31, 2015, and a comparator cohort of 25 patients with biopsy-proven ATTR V122I amyloidosis recruited from September 1, 2009, through November 31, 2014, comprised the development cohort. Twenty-seven African American patients and 9 patients with ATTR V122I amyloidosis comprised the validation cohort. Main Outcomes and Measures Circulating RBP4, TTR, B-type natriuretic peptide (BNP), and troponin I (TnI) concentrations and electrocardiographic, echocardiographic, and clinical characteristics were assessed in all patients. Receiver operating characteristic (ROC) analysis was performed to identify optimal thresholds for ATTR V122I amyloidosis identification. A clinical prediction rule was developed using penalized logistic regression, evaluated using ROC analysis and validated in an independent cohort of cases and controls. Results Age, sex, and BNP and TnI concentrations were similar between the 25 patients with ATTR V122I amyloidosis (mean [SD] age, 72.2 [7.4] years; 18 male [72%]) and the 50 controls (mean [SD] age, 69.2 [5.7] years; 31 male [62%]). Serum RBP4 concentration was lower in patients with ATTR V122I amyloidosis compared with nonamyloid controls (31.5 vs 49.4 µg/mL, P < .001), and the difference persisted after controlling for potential confounding variables. Left ventricular ejection fraction was lower in patients with ATTR V122I amyloidosis (mean [SD], 40% [14%] vs 57% [14%], P < .001), whereas interventricular septal diameter was higher (mean [SD], 16 [3] vs 14 [2] mm, P < .001). The ROC analysis identified RBP4 as a sensitive identifier of ATTR V122I amyloidosis (area under the curve [AUC] = 0.78; 95% CI, 0.67-0.88). A clinical prediction algorithm composed of RBP4, TTR, left ventricular ejection fraction, interventricular septal diameter, mean limb lead QRS voltage, and grade 3 diastolic dysfunction yielded excellent discriminatory capacity for ATTR V122I amyloidosis (AUC = 0.97; 95% CI, 0.93-1.00), whereas a 4-parameter model, including RBP4 concentration, retained excellent discrimination (AUC = 0.92; 95% CI, 0.86-0.99). The models maintained excellent discrimination in the validation cohort. Conclusions and Relevance A prediction model using circulating RBP4 concentration and readily available clinical parameters accurately discriminated ATTR V122I amyloidosis from nonamyloid HF in a case-matched cohort. This clinical algorithm may be useful for identification of ATTR V122I amyloidosis in elderly African American patients with HF.
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Affiliation(s)
- Marios Arvanitis
- Department of Medicine, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts
| | - Clarissa M Koch
- Amyloidosis Center, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts3Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts
| | - Gloria G Chan
- Amyloidosis Center, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts
| | - Celia Torres-Arancivia
- Amyloidosis Center, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts
| | - Michael P LaValley
- Department of Biostatistics, Boston University School of Public Health, Boston, Massachusetts
| | - Daniel R Jacobson
- Department of Medicine, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts2Amyloidosis Center, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts5Hematology/Oncology Section, Medical Service, Veterans Affairs Boston Healthcare System, Boston, Massachusetts
| | - John L Berk
- Department of Medicine, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts2Amyloidosis Center, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts
| | - Lawreen H Connors
- Amyloidosis Center, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts3Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts
| | - Frederick L Ruberg
- Amyloidosis Center, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts6Section of Cardiovascular Medicine, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts
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17
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Abstract
Much evidence has accumulated in the literature over the last fifteen years that indicates vitamin A has a role in metabolic disease prevention and causation. This literature proposes that vitamin A can affect obesity development and the development of obesity-related diseases including insulin resistance, type 2 diabetes, hepatic steatosis and steatohepatitis, and cardiovascular disease. Retinoic acid, the transcriptionally active form of vitamin A, accounts for many of the reported associations. However, a number of proteins involved in vitamin A metabolism, including retinol-binding protein 4 (RBP4) and aldehyde dehydrogenase 1A1 (ALDH1A1, alternatively known as retinaldehyde dehydrogenase 1 or RALDH1), have also been identified as being associated with metabolic disease. Some of the reported effects of these vitamin A-related proteins are proposed to be independent of their roles in assuring normal retinoic acid homeostasis. This review will consider both human observational data as well as published data from molecular studies undertaken in rodent models and in cells in culture. The primary focus of the review will be on the effects that vitamin A per se and proteins involved in vitamin A metabolism have on adipocytes, adipose tissue biology, and adipose-related disease, as well as on early stage liver disease, including non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH).
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Affiliation(s)
- William S Blaner
- Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York 10032.
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18
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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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19
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Niemietz C, Fleischhauer L, Sandfort V, Guttmann S, Zibert A, Schmidt HHJ. Hepatocyte-like cells reveal novel role of SerpinA1 in transthyretin amyloidosis. J Cell Sci 2018; 131:jcs.219824. [DOI: 10.1242/jcs.219824] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 09/18/2018] [Indexed: 01/07/2023] Open
Abstract
Transthyretin (TTR)-related familial amyloid polyneuropathy (ATTR) results from aggregation and extracellular disposition of misfolded TTR variants. Growing evidence suggests the importance of hepatic chaperones for modulation of pathogenesis. We took advantage of iPSC-derived hepatocyte-like cells (HLCs) derived from ATTR patients (ATTR-HLCs) to compare chaperone gene expression to healthy individuals (H-HLCs). From the set of genes analyzed, chaperones that are predominantly located extracellularly were differently expressed. Expression of the chaperones showed a high correlation with TTR in both ATTR-HLCs and H-HLCs. In contrast, after TTR knockdown, the correlation was mainly affected in ATTR-HLCs suggesting that variant TTR expression triggers abberant chaperone expression. Serpin peptidase inhibitor clade A member 1 (SERPINA1/alpha-1 antitrypsin) was the only extracellular chaperone that was markedly upregulated after TTR knockdown in ATTR-HLCs. Co-immunoprecipitation revealed that SerpinA1 physically interacts with TTR. In vitro assays indicated that SerpinA1 can interfere with TTR aggregation. Taken together, our results suggest that extracellular chaperones play a crucial role in ATTR pathogenesis, in particular SerpinA1, which may affect amyloid formation.
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Affiliation(s)
- Christoph Niemietz
- Medizinische Klinik B für Gastroenterologie und Hepatologie, Universitätsklinikum Münster, Münster, Germany
| | - Lutz Fleischhauer
- Medizinische Klinik B für Gastroenterologie und Hepatologie, Universitätsklinikum Münster, Münster, Germany
- Present address: Fakultät für angewandte Naturwissenschaften und Mechatronik, Hochschule München, München, Germany
| | - Vanessa Sandfort
- Medizinische Klinik B für Gastroenterologie und Hepatologie, Universitätsklinikum Münster, Münster, Germany
| | - Sarah Guttmann
- Medizinische Klinik B für Gastroenterologie und Hepatologie, Universitätsklinikum Münster, Münster, Germany
| | - Andree Zibert
- Medizinische Klinik B für Gastroenterologie und Hepatologie, Universitätsklinikum Münster, Münster, Germany
| | - Hartmut H.-J. Schmidt
- Medizinische Klinik B für Gastroenterologie und Hepatologie, Universitätsklinikum Münster, Münster, Germany
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20
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Yokota S, Oshio S. A simple and robust quantitative analysis of retinol and retinyl palmitate using a liquid chromatographic isocratic method. J Food Drug Anal 2017; 26:504-511. [PMID: 29567219 PMCID: PMC9322232 DOI: 10.1016/j.jfda.2017.07.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 07/05/2017] [Accepted: 07/07/2017] [Indexed: 11/05/2022] Open
Abstract
Vitamin A is a vital nutritional substances that regulates biological activities including development, but is also associated with disease onset. The extent of vitamin A intake influences the retinoid content in the liver, the most important organ for the storage of vitamin A. Measurement of endogenous retinoid in biological samples is important to understand retinoid homeostasis. Here we present a reliable, highly sensitive, and robust method for the quantification of retinol and retinyl palmitate using a reverse-phase HPLC/ UV isocratic method. We determined the impact of chronic dietary vitamin A on retinoid levels in livers of mice fed an AIN-93G semi-purified diet (4 IU/g) compared with an excess vitamin A diet (1000 IU/g) over a period from birth to 10 weeks of age. Coefficients of variation for intra-assays for both retinoids were less than 5%, suggesting a higher reproducibility than any other HPLC/UV gradient method. Limits of detection and quantification for retinol were 0.08 pmol, and 0.27 pmol, respectively, which are remarkably higher than previous results. Supplementation with higher doses of vitamin A over the study period significantly increased liver retinol and retinyl palmitate concentrations in adult mice. The assays described here provide a sensitive and rigorous quantification of endogenous retinol and retinyl palmitate, which can be used to help determine retinoid homeostasis in disease states, such as toxic hepatitis and liver cancer.
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Affiliation(s)
- Satoshi Yokota
- Department of Hygiene Chemistry, School of Pharmaceutical Sciences, Ohu University, 31-3 Misumido, Tomitamachi, Koriyama, Fukushima 963-8611, Japan.
| | - Shigeru Oshio
- Department of Hygiene Chemistry, School of Pharmaceutical Sciences, Ohu University, 31-3 Misumido, Tomitamachi, Koriyama, Fukushima 963-8611, Japan
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21
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Liu L, Suzuki T, Shen J, Wakana S, Araki K, Yamamura KI, Lei L, Li Z. Rescue of retinal morphology and function in a humanized mouse at the mouse retinol-binding protein locus. J Transl Med 2017; 97:395-408. [PMID: 28134916 DOI: 10.1038/labinvest.2016.156] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 12/07/2016] [Accepted: 12/12/2016] [Indexed: 11/09/2022] Open
Abstract
Retinol-binding protein RBP4 is the specific carrier for retinol in the blood. We previously produced a Rbp4-deficient (Rbp4-/-) mouse that showed electroretinogram (ERG) abnormalities, accompanied by histological and electron-microscopic changes such as fewer synapses in the inner plexiform layer in the central retina. To address whether human RBP4 gene expression can rescue the phenotypes observed in Rbp4-/- mice, we produced a humanized (Rbp4hRBP4orf/ hRBP4orf) mouse with a human RBP4 open reading frame in the mouse Rbp4 locus using a Cre-mutant lox recombination system. In Rbp4hRBP4orf/hRBP4orf mice, the tissue-specific expression pattern of hRBP4orf was roughly the same as that of mouse Rbp4. ERG and morphological abnormalities observed in Rbp4-/- mice were rescued in Rbp4hRBP4orf/hRBP4orf mice as early as 7 weeks of age. The temporal expression pattern of hRBP4orf in the liver of Rbp4hRBP4orf/hRBP4orf mice was similar to that of mouse Rbp4 in Rbp4+/+mice. In contrast, hRBP4orf expression levels in eyes were significantly lower at 6 and 12 weeks of age compared with mouse Rbp4 but were restored to the control levels at 24 weeks. The serum hRBP4 levels in Rbp4hRBP4orf/hRBP4orf mice were approximately 30% of those in Rbp4+/+ at all ages examined. In accordance with this finding, the plasma retinol levels remained low in Rbp4hRBP4orf/hRBP4orf mice. Retinol accumulation in the liver occurred in control and Rbp4hRBP4orf/hRBP4orf mice but was higher in Rbp4hRBP4orf/hRBP4orf mice at 30 weeks of age. Mouse transthyretin expression was not altered in Rbp4-/- or Rbp4hRBP4orf/hRBP4orf mice. Taken together, 30% of the serum RBP4 level was sufficient to correct the abnormal phenotypes observed in Rbp4-/- mice.
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Affiliation(s)
- Li Liu
- Department of Histology and Embryology, Harbin Medical University, Harbin, Heilongjiang, China.,Yamamura Project Laboratory, Institute of Resource Development and Analysis, Kumamoto University, Kumamoto, Kumamoto, Japan
| | - Tomohiro Suzuki
- Technology and Development Team for Mouse Phenotype Analysis, RIKEN BioResource Center, Tsukuba, Ibaraki, Japan
| | - Jingling Shen
- Department of Histology and Embryology, Harbin Medical University, Harbin, Heilongjiang, China
| | - Shigeharu Wakana
- Technology and Development Team for Mouse Phenotype Analysis, RIKEN BioResource Center, Tsukuba, Ibaraki, Japan
| | - Kimi Araki
- Division of Developmental Genetics, Institute of Resource Development and Analysis, Kumamoto University, Kumamoto, Kumamoto, Japan
| | - Ken-Ichi Yamamura
- Yamamura Project Laboratory, Institute of Resource Development and Analysis, Kumamoto University, Kumamoto, Kumamoto, Japan
| | - Lei Lei
- Department of Histology and Embryology, Harbin Medical University, Harbin, Heilongjiang, China
| | - Zhenghua Li
- Department of Histology and Embryology, Harbin Medical University, Harbin, Heilongjiang, China.,Yamamura Project Laboratory, Institute of Resource Development and Analysis, Kumamoto University, Kumamoto, Kumamoto, Japan
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22
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Molecular Basis for Vitamin A Uptake and Storage in Vertebrates. Nutrients 2016; 8:nu8110676. [PMID: 27792183 PMCID: PMC5133064 DOI: 10.3390/nu8110676] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 09/30/2016] [Accepted: 10/18/2016] [Indexed: 01/27/2023] Open
Abstract
The ability to store and distribute vitamin A inside the body is the main evolutionary adaptation that allows vertebrates to maintain retinoid functions during nutritional deficiencies and to acquire new metabolic pathways enabling light-independent production of 11-cis retinoids. These processes greatly depend on enzymes that esterify vitamin A as well as associated retinoid binding proteins. Although the significance of retinyl esters for vitamin A homeostasis is well established, until recently, the molecular basis for the retinol esterification enzymatic activity was unknown. In this review, we will look at retinoid absorption through the prism of current biochemical and structural studies on vitamin A esterifying enzymes. We describe molecular adaptations that enable retinoid storage and delineate mechanisms in which mutations found in selective proteins might influence vitamin A homeostasis in affected patients.
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23
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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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Abstract
It is well established that chylomicron remnant (dietary) vitamin A is taken up from the circulation by hepatocytes, but more than 80 % of the vitamin A in the liver is stored in hepatic stellate cells (HSC). It presently is not known how vitamin A is transferred from hepatocytes to HSCs for storage. Since retinol-binding protein 4 (RBP4), a protein that is required for mobilizing stored vitamin A, is synthesized solely by hepatocytes and not HSCs, it similarly is not known how vitamin A is transferred from HSCs to hepatocytes. Although it has long been thought that RBP4 is absolutely essential for delivering vitamin A to tissues, recent research has proven that this notion is incorrect since total RBP4-deficiency is not lethal. In addition to RBP4, vitamin A is also found in the circulation bound to lipoproteins and as retinoic acid bound to albumin. It is not known how these different circulating pools of vitamin A contribute to the vitamin A needs of different tissues. In our view, better insight into these three issues is required to better understand vitamin A absorption, storage and mobilization. Here, we provide an up to date synthesis of current knowledge regarding the intestinal uptake of dietary vitamin A, the storage of vitamin A within the liver, and the mobilization of hepatic vitamin A stores, and summarize areas where our understanding of these processes is incomplete.
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Abstract
Plasma transthyretin (TTR) is a plasma protein secreted by the liver that circulates bound to retinol-binding protein 4 (RBP4) and its retinol ligand. TTR is the sole plasma protein that reveals from birth to old age evolutionary patterns that are closely superimposable to those of lean body mass (LBM) and thus works as the best surrogate analyte of LBM. Any alteration in energy-to-protein balance impairs the accretion of LBM reserves and causes early depression of TTR production. In acute inflammatory states, cytokines induce urinary leakage of nitrogenous catabolites, deplete LBM stores, and cause an abrupt decrease in TTR and RBP4 concentrations. As a result, thyroxine and retinol ligands are released in free form, creating a second frontline that strengthens that primarily initiated by cytokines. Malnutrition and inflammation thus keep in check TTR and RBP4 secretion by using distinct and unrelated physiologic pathways, but they operate in concert to downregulate LBM stores. The biomarker complex integrates these opposite mechanisms at any time and thereby constitutes an ideally suited tool to determine residual LBM resources still available for metabolic responses, hence predicting outcomes of the most interwoven disease conditions.
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Affiliation(s)
- Yves Ingenbleek
- Laboratory of Nutrition, Faculty of Pharmacy, University Louis Pasteur, Strasbourg, France; and
| | - Larry H Bernstein
- Laboratory of Clinical Pathology, New York Methodist Hospital, Weill-Cornell University, New York, NY
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Zemany L, Bhanot S, Peroni OD, Murray SF, Moraes-Vieira PM, Castoldi A, Manchem P, Guo S, Monia BP, Kahn BB. Transthyretin Antisense Oligonucleotides Lower Circulating RBP4 Levels and Improve Insulin Sensitivity in Obese Mice. Diabetes 2015; 64:1603-14. [PMID: 25524914 PMCID: PMC4407860 DOI: 10.2337/db14-0970] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 12/11/2014] [Indexed: 12/27/2022]
Abstract
Circulating transthyretin (TTR) is a critical determinant of plasma retinol-binding protein 4 (RBP4) levels. Elevated RBP4 levels cause insulin resistance, and the lowering of RBP4 levels improves glucose homeostasis. Since lowering TTR levels increases renal clearance of RBP4, we determined whether decreasing TTR levels with antisense oligonucleotides (ASOs) improves glucose metabolism and insulin sensitivity in obesity. TTR-ASO treatment of mice with genetic or diet-induced obesity resulted in an 80-95% decrease in circulating levels of TTR and RBP4. Treatment with TTR-ASOs, but not control ASOs, decreased insulin levels by 30-60% and improved insulin sensitivity in ob/ob mice and high-fat diet-fed mice as early as after 2 weeks of treatment. The reduced insulin levels were sustained for up to 9 weeks of treatment and were associated with reduced adipose tissue inflammation. Body weight was not changed. TTR-ASO treatment decreased LDL cholesterol in high-fat diet-fed mice. The glucose infusion rate during a hyperinsulinemic-euglycemic clamp was increased by 50% in high-fat diet-fed mice treated with TTR-ASOs, demonstrating improved insulin sensitivity. This was also demonstrated by 20% greater inhibition of hepatic glucose production, a 45-60% increase of glucose uptake into skeletal and cardiac muscle, and a twofold increase in insulin signaling in muscle. These data show that decreasing circulating TTR levels or altering TTR-RBP4 binding could be a potential therapeutic approach for the treatment of type 2 diabetes.
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Affiliation(s)
- Laura Zemany
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
| | | | - Odile D Peroni
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
| | | | - Pedro M Moraes-Vieira
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
| | - Angela Castoldi
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
| | | | | | | | - Barbara B Kahn
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
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Alshehri B, D'Souza DG, Lee JY, Petratos S, Richardson SJ. The diversity of mechanisms influenced by transthyretin in neurobiology: development, disease and endocrine disruption. J Neuroendocrinol 2015; 27:303-23. [PMID: 25737004 DOI: 10.1111/jne.12271] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Revised: 02/23/2015] [Accepted: 02/24/2015] [Indexed: 12/12/2022]
Abstract
Transthyretin (TTR) is a protein that binds and distributes thyroid hormones (THs). TTR synthesised in the liver is secreted into the bloodstream and distributes THs around the body, whereas TTR synthesised in the choroid plexus is involved in movement of thyroxine from the blood into the cerebrospinal fluid and the distribution of THs in the brain. This is important because an adequate amount of TH is required for normal development of the brain. Nevertheless, there has been heated debate on the role of TTR synthesised by the choroid plexus during the past 20 years. We present both sides of the debate and how they can be reconciled by the discovery of TH transporters. New roles for TTR have been suggested, including the promotion of neuroregeneration, protection against neurodegeneration, and involvement in schizophrenia, behaviour, memory and learning. Recently, TTR synthesis was revealed in neurones and peripheral Schwann cells. Thus, the synthesis of TTR in the central nervous system (CNS) is more extensive than previously considered and bolsters the hypothesis that TTR may play wide roles in neurobiological function. Given the high conservation of TTR structure, function and tissue specificity and timing of gene expression, this implies that TTR has a fundamental role, during development and in the adult, across vertebrates. An alarming number of 'unnatural' chemicals can bind to TTR, thus potentially interfering with its functions in the brain. One role of TTR is delivery of THs throughout the CNS. Reduced TH availability during brain development results in a reduced IQ. The combination of the newly discovered sites of TTR synthesis in the CNS, the increasing number of neurological diseases being associated with TTR, the newly discovered functions of TTR and the awareness of the chemicals that can interfere with TTR biology render this a timely review on TTR in neurobiology.
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Affiliation(s)
- B Alshehri
- School of Medical Sciences, RMIT University, Bundoora, VIC, Australia
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Lv W, Chen J, Chen W, Hou P, Pang CP, Chen H. Multimodal retinal imaging in a Chinese kindred with familial amyloid polyneuropathy secondary to transthyretin Ile107Met mutation. Eye (Lond) 2014; 28:452-8. [PMID: 24480837 DOI: 10.1038/eye.2014.10] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Accepted: 12/10/2013] [Indexed: 12/19/2022] Open
Abstract
OBJECTIVE To investigate the ocular phenotype and gene mutation of a Chinese pedigree with familial amyloid polyneuropathy (FAP) and vitreous amyloidosis. METHODS A Chinese pedigree with familial amyloid polyneuropathy and vitreous amyloidosis was recruited. Combined phacoemulsification, vitrectomy and intraocular lens implantation were performed on the right eye of the index patient. Ophthalmic investigations were performed before and after surgery. The DNA from the pedigree was sequenced for the transthyretin (TTR) gene. RESULTS After vitrectomy, the best-corrected visual acuity of the patient improved from counting finger to 20/20. Red-free confocal ophthalmoscopy demonstrated perifoveal ring and several perivessel white sheaths. Optical coherence tomography (OCT) revealed cotton wool like reflections on the vitreoretinal interface. Electroretinogram and autofluorescence was normal. Amyloid was present in the vitreous specimen. A substitution of T to G at nucleotide 381 in exon 4 of TTR DNA (Ile107Met) was found. This mutation co-segregated with phenotype in the pedigree and was not detected in 200 controls. CONCLUSIONS TTR Ile107Met mutation is associated with vitreous amyloidosis and FAP. OCT and red-free imaging are helpful in identifying amyloid deposits in the retina.
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Affiliation(s)
- W Lv
- Joint Shantou International Eye Center, Shantou University and the Chinese University of Hong Kong, Shantou, China
| | - J Chen
- Joint Shantou International Eye Center, Shantou University and the Chinese University of Hong Kong, Shantou, China
| | - W Chen
- Joint Shantou International Eye Center, Shantou University and the Chinese University of Hong Kong, Shantou, China
| | - P Hou
- Joint Shantou International Eye Center, Shantou University and the Chinese University of Hong Kong, Shantou, China
| | - C P Pang
- 1] Joint Shantou International Eye Center, Shantou University and the Chinese University of Hong Kong, Shantou, China [2] Department of Ophthalmology and Visual Sciences, the Chinese University of Hong Kong, Hong Kong, China
| | - H Chen
- 1] Joint Shantou International Eye Center, Shantou University and the Chinese University of Hong Kong, Shantou, China [2] Department of Ophthalmology and Visual Sciences, the Chinese University of Hong Kong, Hong Kong, China
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Marques F, Sousa JC, Sousa N, Palha JA. Blood-brain-barriers in aging and in Alzheimer's disease. Mol Neurodegener 2013; 8:38. [PMID: 24148264 PMCID: PMC4015275 DOI: 10.1186/1750-1326-8-38] [Citation(s) in RCA: 198] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2013] [Accepted: 09/23/2013] [Indexed: 12/26/2022] Open
Abstract
The aging process correlates with a progressive failure in the normal cellular and organ functioning; these alterations are aggravated in Alzheimer's disease (AD). In both aging and AD there is a general decrease in the capacity of the body to eliminate toxic compounds and, simultaneously, to supply the brain with relevant growth and nutritional factors. The barriers of the brain are targets of this age related dysfunction; both the endothelial cells of the blood-brain barrier and the choroid plexus epithelial cells of the blood-cerebrospinal fluid barrier decrease their secretory capacity towards the brain and their ability to remove toxic compounds from the brain. Additionally, during normal aging and in AD, the permeability of the brain barriers increase. As such, a greater contact of the brain parenchyma with the blood content alters the highly controlled neural environment, which impacts on neural function. Of interest, the brain barriers are more than mere obstacles to the passage of molecules and cells, and therefore active players in brain homeostasis, which is still to be further recognized and investigated in the context of health and disease. Herein, we provide a review on how the brain barriers change during aging and in AD and how these processes impact on brain function.
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Affiliation(s)
- Fernanda Marques
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Campus Gualtar, Braga 4710-057, Portugal
- ICVS/3B’s - PT Government Associate Laboratory, Braga/Guimaraes, Portugal
| | - João Carlos Sousa
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Campus Gualtar, Braga 4710-057, Portugal
- ICVS/3B’s - PT Government Associate Laboratory, Braga/Guimaraes, Portugal
| | - Nuno Sousa
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Campus Gualtar, Braga 4710-057, Portugal
- ICVS/3B’s - PT Government Associate Laboratory, Braga/Guimaraes, Portugal
| | - Joana Almeida Palha
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Campus Gualtar, Braga 4710-057, Portugal
- ICVS/3B’s - PT Government Associate Laboratory, Braga/Guimaraes, Portugal
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Chau J, Moza D, Hossain N, Lee JK, Bienenstock J, Karimi K. Increased production of IFN-γ by natural killer cells triggered with bone marrow-derived dendritic cells cultured in the presence of retinoic acid. Eur J Pharmacol 2013; 715:321-7. [DOI: 10.1016/j.ejphar.2013.04.050] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 04/22/2013] [Accepted: 04/26/2013] [Indexed: 11/26/2022]
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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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Nasim FUH, Ejaz S, Ashraf M, Asif AR, Oellerich M, Ahmad G, Malik GA, Attiq-Ur-Rehman. Potential biomarkers in the sera of breast cancer patients from bahawalpur, pakistan. BIOMARKERS IN CANCER 2012; 4:19-34. [PMID: 24179392 PMCID: PMC3791917 DOI: 10.4137/bic.s10502] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Most of the approximately 90,000 cases of Breast Cancer (BC) documented annually in Pakistan are not diagnosed properly because of lack of suitable markers. We performed serum proteome expression profiling of BC and benign breast disease (BBD) patients with the aim to identify biomarkers that can be helpful for diagnosis and prognosis of the disease. Sera of patients were analyzed by one-dimensional SDS polyacrylamide gel electrophoresis (PAGE). Differentially expressed proteins were subjected to identification through LC-MS/MS analysis. In majority of the BC cases some acute phase proteins (APP) and some complement system components (C3 and C8) containing fractions were up-regulated with the exception of transthyretin (TTR) which was predominantly (68.75%) down-regulated (n = 33/48) in the sera of these patients. Varying expression patterns were observed in BBD patients and healthy controls. These differentially expressed proteins have the potential to serve as diagnostic biomarkers for BC as well as benign breast diseases.
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Affiliation(s)
- Faiz-Ul-Hassan Nasim
- Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur, Pakistan. ; Department of Biochemistry and Biotechnology, The Islamia University of Bahawalpur, Bahawalpur, Pakistan
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Shao J, Xin Y, Yao Y, Zhu J. Functional analysis of misfolded transthyretin extracted from abnormal vitreous with high myopia related ocular pathologies. Clin Chim Acta 2012; 415:20-4. [PMID: 22975527 DOI: 10.1016/j.cca.2012.09.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Revised: 09/04/2012] [Accepted: 09/05/2012] [Indexed: 10/27/2022]
Abstract
BACKGROUND In the development of high myopia, some secondary ocular diseases such as macular detachment (MD) and macular hole (MH) may occur owing to the elongation of the eyeball. Higher concentrations of misfolded transthyretin (TTR) had been detected in abnormal vitreous humor, but the mechanisms are still unclear. METHOD TTRs of high myopia and healthy vitreous were purified with TTR polyclonal antibody-Sepharose. Gel exclusion chromatography, cleavage activity assay and a fluorescent probe were employed for the functional comparison of natural and abnormal TTRs. RESULTS Compared with natural transthyretin, MH TTR showed lower retinol-binding protein (RBP) binding ability; and MD TTR could not bind with RBP at all. Additionally, MH and MD TTR did not reveal cleavage activity against apolipoprotein AI (apoA-I). Furthermore, the kinetic parameters of the interactions between abnormal TTRs and a thyroxine-like fluorescent probe were quite different from those of natural TTR. CONCLUSIONS The results suggested that misfolded TTRs in MD and MH patients' vitreous completely or partially lost natural bio-functions; and this should be associated with abnormal high TTR levels.
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Affiliation(s)
- Jun Shao
- Department of Ophthalmology, The Wuxi People's Hospital, 299 Qing yang Road, Wuxi 214023, People's Republic of China.
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Oliveira SM, Cardoso I, Saraiva MJ. Transthyretin: roles in the nervous system beyond thyroxine and retinol transport. Expert Rev Endocrinol Metab 2012; 7:181-189. [PMID: 30764010 DOI: 10.1586/eem.12.2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Transthyretin (TTR) is a plasma- and cerebrospinal fluid-circulating protein. Besides the primordially attributed systemic role as a transporter molecule of thyroxine (T4) and retinol (through the binding to retinol-binding protein [RBP]), TTR has been recognized as a protein with important functions in several aspects of the nervous system physiology. TTR has been shown to play an important role in behavior, cognition, amidated neuropeptide processing and nerve regeneration. Furthermore, it has been proposed that TTR is neuroprotective in Alzheimer's disease and cerebral ischemia. Mutations in TTR are a well-known cause of familial amyloidotic polyneuropathy, an autosomal dominant neurodegenerative disorder characterized by systemic deposition of TTR amyloid fibrils, particularly in the peripheral nervous system. The purpose of this review is to highlight the roles of TTR in the nervous system, beyond its systemic role as a transporter molecule of T4 and RBP-retinol.
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Affiliation(s)
- Sandra Marisa Oliveira
- a Molecular Neurobiology, IBMC- Instituto de Biologia Molecular e Celular, Rua do Campo Alegre, 823, 4150-180, Porto, Portugal
| | - Isabel Cardoso
- a Molecular Neurobiology, IBMC- Instituto de Biologia Molecular e Celular, Rua do Campo Alegre, 823, 4150-180, Porto, Portugal
- b Escola Superior de Tecnologia da Saúde do Porto, Instituto Politécnico do Porto, Portugal
| | - Maria João Saraiva
- a Molecular Neurobiology, IBMC- Instituto de Biologia Molecular e Celular, Rua do Campo Alegre, 823, 4150-180, Porto, Portugal
- c ICBAS - Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Portugal.
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Nitrofen interferes with trophoblastic expression of retinol-binding protein and transthyretin during lung morphogenesis in the nitrofen-induced congenital diaphragmatic hernia model. Pediatr Surg Int 2012; 28:143-8. [PMID: 22015466 DOI: 10.1007/s00383-011-2995-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
BACKGROUND Retinoids play a key role in lung development. Retinoid signaling pathway has been shown to be disrupted in the nitrofen model of congenital diaphragmatic hernia (CDH) but the exact mechanism is not clearly understood. Retinol-binding protein (RBP) and transthyretin (TTR) are transport proteins for delivery of retinol to the tissues via circulation. Previous studies have shown that pulmonary retinol levels are decreased during lung morphogenesis in the nitrofen CDH model. In human newborns with CDH, both retinol and RBP levels are decreased. It has been reported that maternal RBP does not cross the placenta and the fetus produces its own RBP by trophoblast. RBP and TTR synthesized in the fetus are essential for retinol transport to the developing organs including lung morphogenesis. We hypothesized that nitrofen interferes with the trophoblastic expression of RBP and TTR during lung morphogenesis and designed this study to examine the trophoblastic expression of RBP and TTR, and the total level of RBP and TTR in the lung in the nitrofen model of CDH. METHODS Pregnant rats were exposed to either olive oil or nitrofen on day 9 of gestation (D9). Fetal lungs and placenta harvested on D21 and divided into two groups: control (n = 8) and nitrofen with CDH (n = 8). Total lung RBP and TTR levels using protein extraction were compared with enzyme linked immunoassay (ELISA). Immunohistochemistry was performed to evaluate trophoblastic RBP and TTR expression. RESULTS Total protein levels of lung RBP and TTR were significantly lower in CDH (0.26 ± 0.003 and 6.4 ± 0.5 μg/mL) compared with controls (0.4 ± 0.001 and 9.9 ± 1.6 μg/mL, p < 0.05). In the control group, immunohistochemical staining showed strong immunoreactivity of RBP and TTR in the trophoblast compared to CDH group. CONCLUSIONS Decreased trophoblast expression of retinol transport proteins suggest that nitrofen may interfere with the fetal retinol transport resulting in reduced pulmonary RBP and TTR levels and causing pulmonary hypoplasia in CDH.
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Shirakami Y, Lee SA, Clugston RD, Blaner WS. Hepatic metabolism of retinoids and disease associations. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1821:124-36. [PMID: 21763780 PMCID: PMC3488285 DOI: 10.1016/j.bbalip.2011.06.023] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2011] [Revised: 06/14/2011] [Accepted: 06/21/2011] [Indexed: 12/12/2022]
Abstract
The liver is the most important tissue site in the body for uptake of postprandial retinoid, as well as for retinoid storage. Within the liver, both hepatocytes and hepatic stellate cells (HSCs) are importantly involved in retinoid metabolism. Hepatocytes play an indispensable role in uptake and processing of dietary retinoid into the liver, and in synthesis and secretion of retinol-binding protein (RBP), which is required for mobilizing hepatic retinoid stores. HSCs are the central cellular site for retinoid storage in the healthy animal, accounting for as much as 50-60% of the total retinoid present in the entire body. The liver is also an important target organ for retinoid actions. Retinoic acid is synthesized in the liver and can interact with retinoid receptors which control expression of a large number of genes involved in hepatic processes. Altered retinoid metabolism and the accompanying dysregulation of retinoid signaling in the liver contribute to hepatic disease. This is related to HSCs, which contribute significantly to the development of hepatic disease when they undergo a process of cellular activation. HSC activation results in the loss of HSC retinoid stores and changes in extracellular matrix deposition leading to the onset of liver fibrosis. An association between hepatic disease progression and decreased hepatic retinoid storage has been demonstrated. In this review article, we summarize the essential role of the liver in retinoid metabolism and consider briefly associations between hepatic retinoid metabolism and disease. This article is part of a Special Issue entitled Retinoid and Lipid Metabolism.
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Affiliation(s)
- Yohei Shirakami
- Department of Medicine, College of Physcians and Surgeons, Columbia University, 630 W, 168th St, New York, NY 10032, USA
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Li X, Buxbaum JN. Transthyretin and the brain re-visited: is neuronal synthesis of transthyretin protective in Alzheimer's disease? Mol Neurodegener 2011; 6:79. [PMID: 22112803 PMCID: PMC3267701 DOI: 10.1186/1750-1326-6-79] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2011] [Accepted: 11/23/2011] [Indexed: 12/14/2022] Open
Abstract
Since the mid-1990's a trickle of publications from scattered independent laboratories have presented data suggesting that the systemic amyloid precursor transthyretin (TTR) could interact with the amyloidogenic β-amyloid (Aβ) peptide of Alzheimer's disease (AD). The notion that one amyloid precursor could actually inhibit amyloid fibril formation by another seemed quite far-fetched. Further it seemed clear that within the CNS, TTR was only produced in choroid plexus epithelial cells, not in neurons. The most enthusiastic of the authors proclaimed that TTR sequestered Aβ in vivo resulting in a lowered TTR level in the cerebrospinal fluid (CSF) of AD patients and that the relationship was salutary. More circumspect investigators merely showed in vitro interaction between the two molecules. A single in vivo study in Caenorhabditis elegans suggested that wild type human TTR could suppress the abnormalities seen when Aβ was expressed in the muscle cells of the worm. Subsequent studies in human Aβ transgenic mice, including those from our laboratory, also suggested that the interaction reduced the Aβ deposition phenotype. We have reviewed the literature analyzing the relationship including recent data examining potential mechanisms that could explain the effect. We have proposed a model which is consistent with most of the published data and current notions of AD pathogenesis and can serve as a hypothesis which can be tested.
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Affiliation(s)
- Xinyi Li
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, 10550 North Torrey Pines Rd,, MEM-230, La Jolla, CA 92037, USA
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Flowers MT, Paton CM, O'Byrne SM, Schiesser K, Dawson JA, Blaner WS, Kendziorski C, Ntambi JM. Metabolic changes in skin caused by Scd1 deficiency: a focus on retinol metabolism. PLoS One 2011; 6:e19734. [PMID: 21573029 PMCID: PMC3090422 DOI: 10.1371/journal.pone.0019734] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Accepted: 04/06/2011] [Indexed: 01/28/2023] Open
Abstract
We previously reported that mice with skin-specific deletion of stearoyl-CoA desaturase-1 (Scd1) recapitulated the skin phenotype and hypermetabolism observed in mice with a whole-body deletion of Scd1. In this study, we first performed a diet-induced obesity experiment at thermoneutral temperature (33°C) and found that skin-specific Scd1 knockout (SKO) mice still remain resistant to obesity. To elucidate the metabolic changes in the skin that contribute to the obesity resistance and skin phenotype, we performed microarray analysis of skin gene expression in male SKO and control mice fed a standard rodent diet. We identified an extraordinary number of differentially expressed genes that support the previously documented histological observations of sebaceous gland hypoplasia, inflammation and epidermal hyperplasia in SKO mice. Additionally, transcript levels were reduced in skin of SKO mice for genes involved in fatty acid synthesis, elongation and desaturation, which may be attributed to decreased abundance of key transcription factors including SREBP1c, ChREBP and LXRα. Conversely, genes involved in cholesterol synthesis were increased, suggesting an imbalance between skin fatty acid and cholesterol synthesis. Unexpectedly, we observed a robust elevation in skin retinol, retinoic acid and retinoic acid-induced genes in SKO mice. Furthermore, SEB-1 sebocytes treated with retinol and SCD inhibitor also display an elevation in retinoic acid-induced genes. These results highlight the importance of monounsaturated fatty acid synthesis for maintaining retinol homeostasis and point to disturbed retinol metabolism as a novel contributor to the Scd1 deficiency-induced skin phenotype.
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Affiliation(s)
- Matthew T Flowers
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America.
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D'Ambrosio DN, Clugston RD, Blaner WS. Vitamin A metabolism: an update. Nutrients 2011; 3:63-103. [PMID: 21350678 PMCID: PMC3042718 DOI: 10.3390/nu3010063] [Citation(s) in RCA: 351] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Revised: 12/24/2010] [Accepted: 01/11/2011] [Indexed: 12/18/2022] Open
Abstract
Retinoids are required for maintaining many essential physiological processes in the body, including normal growth and development, normal vision, a healthy immune system, normal reproduction, and healthy skin and barrier functions. In excess of 500 genes are thought to be regulated by retinoic acid. 11-cis-retinal serves as the visual chromophore in vision. The body must acquire retinoid from the diet in order to maintain these essential physiological processes. Retinoid metabolism is complex and involves many different retinoid forms, including retinyl esters, retinol, retinal, retinoic acid and oxidized and conjugated metabolites of both retinol and retinoic acid. In addition, retinoid metabolism involves many carrier proteins and enzymes that are specific to retinoid metabolism, as well as other proteins which may be involved in mediating also triglyceride and/or cholesterol metabolism. This review will focus on recent advances for understanding retinoid metabolism that have taken place in the last ten to fifteen years.
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Affiliation(s)
- Diana N D'Ambrosio
- Department of Medicine and Institute of Human Nutrition, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
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Feng T, Cong Y, Qin H, Benveniste EN, Elson CO. Generation of mucosal dendritic cells from bone marrow reveals a critical role of retinoic acid. THE JOURNAL OF IMMUNOLOGY 2010; 185:5915-25. [PMID: 20944006 DOI: 10.4049/jimmunol.1001233] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
It is unknown how dendritic cells (DCs) become specialized as mucosal DCs and maintain intestinal homeostasis. We report that a subset of bone marrow cells freshly isolated from C57BL/6 mice express the retinoic acid (RA)-synthesizing enzyme aldehyde dehydrogenase family 1, subfamily A2 (ALDH1a2) and are capable of providing RA to DC precursors in the bone marrow microenvironment. RA induced bone marrow-derived DCs to express CCR9 and ALDH1a2 and conferred upon them mucosal DC functions, including induction of Foxp3(+) regulatory T cells, IgA-secreting B cells, and gut-homing molecules. This response of DCs to RA was dependent on a narrow time window and stringent dose effect. RA promoted bone marrow-derived DC production of bioactive TGF-β by inhibiting suppressor of cytokine signaling 3 expression and thereby enhancing STAT3 activation. These RA effects were evident in vivo, in that mucosal DCs from vitamin A-deficient mice had reduced mucosal DC function, namely failure to induce Foxp3(+) regulatory T cells. Furthermore, MyD88 signaling enhanced RA-educated DC ALDH1a2 expression and was required for optimal TGF-β production. These data indicate that RA plays a critical role in the generation of mucosal DCs from bone marrow and in their functional activity.
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Affiliation(s)
- Ting Feng
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Liz MA, Mar FM, Franquinho F, Sousa MM. Aboard transthyretin: From transport to cleavage. IUBMB Life 2010; 62:429-35. [PMID: 20503435 DOI: 10.1002/iub.340] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Transthyretin (TTR) is a plasma and cerebrospinal fluid protein mainly recognized as the transporter of thyroxine (T(4)) and retinol. Mutated TTR leads to familial amyloid polyneuropathy, a neurodegenerative disorder characterized by TTR amyloid deposition particularly in peripheral nerves. Beside its transport activities, TTR is a cryptic protease and participates in the biology of the nervous system. Several studies have been directed at finding new ligands of TTR to further explore the biology of the protein. From the identified ligands, some were in fact TTR protease substrates. In this review, we will discuss the existent information concerning TTR ligands/substrates.
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Affiliation(s)
- Márcia A Liz
- Nerve Regeneration Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Portugal
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O'Byrne SM, Kako Y, Deckelbaum RJ, Hansen IH, Palczewski K, Goldberg IJ, Blaner WS. Multiple pathways ensure retinoid delivery to milk: studies in genetically modified mice. Am J Physiol Endocrinol Metab 2010; 298:E862-70. [PMID: 20040693 PMCID: PMC2853214 DOI: 10.1152/ajpendo.00491.2009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Retinoids are absolutely required for normal growth and development during the postnatal period. We studied the delivery of retinoids to milk, availing of mouse models modified for proteins thought to be essential for this process. Milk retinyl esters were markedly altered in mice lacking the enzyme lecithin:retinol acyltransferase (Lrat(-/-)), indicating that this enzyme is normally responsible for the majority of retinyl esters incorporated into milk and not an acyl-CoA dependent enzyme, as proposed in the literature. Unlike wild-type milk, much of the retinoid in Lrat(-/-) milk is unesterified retinol, not retinyl ester. The composition of the residual retinyl ester present in Lrat(-/-) milk was altered from predominantly retinyl palmitate and stearate to retinyl oleate and medium chain retinyl esters. This was accompanied by increased palmitate and decreased oleate in Lrat(-/-) milk triglycerides. In other studies, we investigated the role of retinol-binding protein in retinoid delivery for milk formation. We found that Rbp(-/-) mice maintain milk retinoid concentrations similar to those in matched wild-type mice. This appears to arise due to greater postprandial delivery of retinoid, a lipoprotein lipase (LPL)-dependent pathway. Importantly, LPL also acts to assure delivery of long-chain fatty acids (LCFA) to milk. The fatty acid transporter CD36 also facilitated LCFA but not retinoid incorporation into milk. Our data show that compensatory pathways for the delivery of retinoids ensure their optimal delivery and that LRAT is the most important enzyme for milk retinyl ester formation.
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Affiliation(s)
- Sheila M O'Byrne
- Institute of Human Nutrition, Columbia University, New York, NY 10032, USA.
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Nunes AF, Liz MA, Franquinho F, Teixeira L, Sousa V, Chenu C, Lamghari M, Sousa MM. Neuropeptide Y expression and function during osteoblast differentiation--insights from transthyretin knockout mice. FEBS J 2009; 277:263-75. [PMID: 19954489 DOI: 10.1111/j.1742-4658.2009.07482.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To better understand the role of neuropeptide Y (NPY) in bone homeostasis, as its function in the regulation of bone mass is unclear, we assessed its expression in this tissue. By immunohistochemistry, we demonstrated, both at embryonic stages and in the adult, that NPY is synthesized by osteoblasts, osteocytes, and chondrocytes. Moreover, peptidylglycine alpha-amidating monooxygenase, the enzyme responsible for NPY activation by amidation, was also expressed in these cell types. Using transthyretin (TTR) KO mice as a model of augmented NPY levels, we showed that this strain has increased NPY content in the bone, further validating the expression of this neuropeptide by bone cells. Moreover, the higher amidated neuropeptide levels in TTR KO mice were related to increased bone mineral density and trabecular volume. Additionally, RT-PCR analysis established that NPY is not only expressed in MC3T3-E1 osteoblastic cells and bone marrow stromal cells (BMSCs), but is also detectable by RIA in BMSCs undergoing osteoblastic differentiation. In agreement with our in vivo observations, in vitro, TTR KO BMSCs differentiated in osteoblasts had increased NPY levels and exhibited enhanced competence in undergoing osteoblastic differentiation. In summary, this work contributes to a better understanding of the role of NPY in the regulation of bone formation by showing that this neuropeptide is expressed in bone cells and that increased amidated neuropeptide content is related to increased bone mass.
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Affiliation(s)
- Ana F Nunes
- Nerve Regeneration, IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Portugal
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Transthyretin: More than meets the eye. Prog Neurobiol 2009; 89:266-76. [DOI: 10.1016/j.pneurobio.2009.07.007] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Revised: 07/24/2009] [Accepted: 07/31/2009] [Indexed: 11/20/2022]
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Poulain S, Evenou F, Carré MC, Corbel S, Vignaud JM, Martinet N. Vitamin A/retinoids signalling in the human lung. Lung Cancer 2009; 66:1-7. [DOI: 10.1016/j.lungcan.2009.03.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2008] [Revised: 12/18/2008] [Accepted: 03/06/2009] [Indexed: 11/29/2022]
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Abstract
Thyroid hormones are involved in growth and development, particularly of the brain. Thus, it is imperative that these hormones get from their site of synthesis to their sites of action throughout the body and the brain. This role is fulfilled by thyroid hormone distributor proteins. Of particular interest is transthyretin, which in mammals is synthesized in the liver, choroid plexus, meninges, retinal and ciliary pigment epithelia, visceral yolk sac, placenta, pancreas and intestines, whereas the other thyroid hormone distributor proteins are synthesized only in the liver. Transthyretin is synthesized by all classes of vertebrates; however, the tissue specificity of transthyretin gene expression varies widely between classes. This review summarizes what is currently known about the evolution of transthyretin synthesis in vertebrates and presents hypotheses regarding tissue-specific synthesis of transthyretin in each vertebrate class.
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Ortiz B, Wassef L, Shabrova E, Cordeddu L, Banni S, Quadro L. Hepatic retinol secretion and storage are altered by dietary CLA: common and distinct actions of CLA c9,t11 and t10,c12 isomers. J Lipid Res 2009; 50:2278-89. [PMID: 19454764 DOI: 10.1194/jlr.m900054-jlr200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Conjugated linoleic acid (CLA) is a polyunsaturated fatty acid obtained from ruminant products. Previous studies in rats and pigs showed that a dietary equimolar mixture of c9,t11 and t10,c12 CLA isomers induces changes in serum and tissue levels of retinoids (vitamin A derivatives). However, the mechanism(s) responsible for these actions remain(s) unexplored. Given the numerous crucial biological functions regulated by retinoids, it is key to establish whether the perturbations in retinoid metabolism induced by dietary CLA mediate some of the beneficial effects associated with intake of this fatty acid or, rather, have adverse consequences on health. To address this important biological question, we began to explore the mechanisms through which dietary CLA alters retinoid metabolism. By using enriched preparations of CLA c9,t11 or CLA t10,c12, we uncoupled the effects of these two CLA isomers on retinoid metabolism. Specifically, we show that both isomers induce hepatic retinyl ester accumulation. However, only CLA t10,c12 enhances hepatic retinol secretion, resulting in increased serum levels of retinol and its specific carrier, retinol-binding protein (RBP). Dietary CLA t10,c12 also redistributes retinoids from the hepatic stores toward the adipose tissue and possibly stimulates hepatic retinoid oxidation. Using mice lacking RBP, we also demonstrate that this key protein in retinoid metabolism mediates hepatic retinol secretion and its redistribution toward fat tissue induced by CLA t10,c12 supplementation.
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Affiliation(s)
- Berenice Ortiz
- Department of Food Science and Rutgers Center for Lipid Research, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, NJ, 08901, USA
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Fleming CE, Mar FM, Franquinho F, Sousa MM. Chapter 17 Transthyretin. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2009; 87:337-46. [DOI: 10.1016/s0074-7742(09)87017-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Sun T, Surles RL, Tanumihardjo SA. Vitamin A concentrations in piglet extrahepatic tissues respond differently ten days after vitamin A treatment. J Nutr 2008; 138:1101-6. [PMID: 18492841 PMCID: PMC2678969 DOI: 10.1093/jn/138.6.1101] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Periodic supplementation to infants and young children is encouraged in developing countries by the WHO. We investigated vitamin A (VA) in extrahepatic tissues of piglets after supplementation with retinyl acetate to determine long-term storage. 3, 4-Didehydroretinyl acetate (DRA) as a tracer was used to evaluate uptake from chylomicra in 4 h. Sows were fed a VA-depleted diet throughout pregnancy and lactation. Male castrated piglets (n = 28, 11.6 +/- 0.5 d) from these sows were weaned onto a VA-free diet for 1 wk, assigned to 4 groups, and dosed orally with 0, 26.2, 52.4, or 105 micromol VA. After 10 d, 5.3 micromol DRA was administered to determine short-term uptake of 3, 4-didehydroretinol (DR). Four hours later, piglets were killed; adrenal glands, kidney, lung, and spleen were collected and analyzed for retinol and DR. Retinol concentrations of kidney and adrenal gland were higher than control, but treated groups did not differ. Retinol concentration was highest in kidney (1.70-2.52 nmol/g), followed by adrenal gland (0.30-0.48 nmol/g), lung (0.15-0.21 nmol/g), and spleen (0.11-0.15 nmol/g). Total retinol in kidney and spleen was different among the groups (P < 0.05). Unesterified retinol was the major VA form; the percent retinol of total VA was lowest in adrenal glands. DR did not differ among the groups. In 4 h, the minimum estimated chylomicron contribution to tissue DR was 63-280% higher than the maximum DR exposure from retinol-binding protein. Constant dietary intake may be important in maintaining VA concentrations in extrahepatic tissues.
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Sousa JC, Marques F, Dias-Ferreira E, Cerqueira JJ, Sousa N, Palha JA. Transthyretin influences spatial reference memory. Neurobiol Learn Mem 2007; 88:381-5. [PMID: 17698379 DOI: 10.1016/j.nlm.2007.07.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2007] [Revised: 07/01/2007] [Accepted: 07/04/2007] [Indexed: 11/19/2022]
Abstract
Transthyretin (TTR) is a plasma and cerebrospinal fluid carrier for thyroxine and retinol, described also to sequester the amyloid beta peptide. TTR levels have been described as decreased in the cerebrospinal fluid of patients with Alzheimer's disease. In order to investigate the role of TTR in learning and memory, we studied young adult and old TTR-null 129/Sv mice for cognitive performance. In the absence of TTR, 5-month-old mice display spatial reference memory impairment when compared to age-matched wild-type mice. Interestingly, while aging in wild-type mice is associated with a worsening reference memory performance, TTR-null mice show no further impairment with increasing age. As a result, no significant differences were found in this spatial reference task in old mice. Our data show that the absence of TTR seems to accelerate the poorer cognitive performance normally associated with aging.
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Affiliation(s)
- João Carlos Sousa
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
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