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Glastonbury CA, Pulit SL, Honecker J, Censin JC, Laber S, Yaghootkar H, Rahmioglu N, Pastel E, Kos K, Pitt A, Hudson M, Nellåker C, Beer NL, Hauner H, Becker CM, Zondervan KT, Frayling TM, Claussnitzer M, Lindgren CM. Machine Learning based histology phenotyping to investigate the epidemiologic and genetic basis of adipocyte morphology and cardiometabolic traits. PLoS Comput Biol 2020; 16:e1008044. [PMID: 32797044 PMCID: PMC7449405 DOI: 10.1371/journal.pcbi.1008044] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Revised: 08/26/2020] [Accepted: 06/11/2020] [Indexed: 12/29/2022] Open
Abstract
Genetic studies have recently highlighted the importance of fat distribution, as well as overall adiposity, in the pathogenesis of obesity-associated diseases. Using a large study (n = 1,288) from 4 independent cohorts, we aimed to investigate the relationship between mean adipocyte area and obesity-related traits, and identify genetic factors associated with adipocyte cell size. To perform the first large-scale study of automatic adipocyte phenotyping using both histological and genetic data, we developed a deep learning-based method, the Adipocyte U-Net, to rapidly derive mean adipocyte area estimates from histology images. We validate our method using three state-of-the-art approaches; CellProfiler, Adiposoft and floating adipocytes fractions, all run blindly on two external cohorts. We observe high concordance between our method and the state-of-the-art approaches (Adipocyte U-net vs. CellProfiler: R2visceral = 0.94, P < 2.2 × 10-16, R2subcutaneous = 0.91, P < 2.2 × 10-16), and faster run times (10,000 images: 6mins vs 3.5hrs). We applied the Adipocyte U-Net to 4 cohorts with histology, genetic, and phenotypic data (total N = 820). After meta-analysis, we found that mean adipocyte area positively correlated with body mass index (BMI) (Psubq = 8.13 × 10-69, βsubq = 0.45; Pvisc = 2.5 × 10-55, βvisc = 0.49; average R2 across cohorts = 0.49) and that adipocytes in subcutaneous depots are larger than their visceral counterparts (Pmeta = 9.8 × 10-7). Lastly, we performed the largest GWAS and subsequent meta-analysis of mean adipocyte area and intra-individual adipocyte variation (N = 820). Despite having twice the number of samples than any similar study, we found no genome-wide significant associations, suggesting that larger sample sizes and a homogenous collection of adipose tissue are likely needed to identify robust genetic associations.
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Affiliation(s)
- Craig A. Glastonbury
- Big Data Institute, University of Oxford, Oxford, United Kingdom
- BenevolentAI, London, United Kingdom
| | - Sara L. Pulit
- Big Data Institute, University of Oxford, Oxford, United Kingdom
| | - Julius Honecker
- Else Kröner-Fresenius-Center for Nutritional Medicine, School of Life Sciences, Technical University of Munich, Freising, Germany
| | - Jenny C. Censin
- Big Data Institute, University of Oxford, Oxford, United Kingdom
- Wellcome Centre for Human Genetics (WCHG), Oxford, United Kingdom
| | - Samantha Laber
- Big Data Institute, University of Oxford, Oxford, United Kingdom
- Broad Institute of MIT and Harvard, Cambridge Massachusetts, United States of America
| | - Hanieh Yaghootkar
- Genetics of Complex Traits, University of Exeter Medical School, Royal Devon & Exeter Hospital, Exeter, United Kingdom
- Research Centre for Optimal Health, School of Life Sciences, University of Westminster, London, United Kingdom
| | - Nilufer Rahmioglu
- Wellcome Centre for Human Genetics (WCHG), Oxford, United Kingdom
- Endometriosis CaRe Centre Oxford, Nuffield Department of Women’s and Reproductive Health, University of Oxford, Oxford, United Kingdom
| | - Emilie Pastel
- Genetics of Complex Traits, University of Exeter Medical School, Royal Devon & Exeter Hospital, Exeter, United Kingdom
| | - Katerina Kos
- Genetics of Complex Traits, University of Exeter Medical School, Royal Devon & Exeter Hospital, Exeter, United Kingdom
| | - Andrew Pitt
- NIHR Exeter Clinical Research Facility, University of Exeter Medical School, University of Exeter and Royal Devon and Exeter NHS Foundation Trust Exeter, United Kingdom
| | - Michelle Hudson
- NIHR Exeter Clinical Research Facility, University of Exeter Medical School, University of Exeter and Royal Devon and Exeter NHS Foundation Trust Exeter, United Kingdom
| | - Christoffer Nellåker
- Big Data Institute, University of Oxford, Oxford, United Kingdom
- Endometriosis CaRe Centre Oxford, Nuffield Department of Women’s and Reproductive Health, University of Oxford, Oxford, United Kingdom
| | - Nicola L. Beer
- Novo Nordisk Research Centre Oxford (NNRCO), Oxford, United Kingdom
| | - Hans Hauner
- Else Kröner-Fresenius-Center for Nutritional Medicine, School of Life Sciences, Technical University of Munich, Freising, Germany
- Institute of Nutritional Medicine, School of Medicine, Technical University of Munich, Munich
- German Center of Diabetes Research, Helmholtz Center Munich, Neuherberg, Germany
| | - Christian M. Becker
- Endometriosis CaRe Centre Oxford, Nuffield Department of Women’s and Reproductive Health, University of Oxford, Oxford, United Kingdom
| | - Krina T. Zondervan
- Wellcome Centre for Human Genetics (WCHG), Oxford, United Kingdom
- Endometriosis CaRe Centre Oxford, Nuffield Department of Women’s and Reproductive Health, University of Oxford, Oxford, United Kingdom
| | - Timothy M. Frayling
- Genetics of Complex Traits, University of Exeter Medical School, Royal Devon & Exeter Hospital, Exeter, United Kingdom
- NIHR Exeter Clinical Research Facility, University of Exeter Medical School, University of Exeter and Royal Devon and Exeter NHS Foundation Trust Exeter, United Kingdom
| | - Melina Claussnitzer
- Broad Institute of MIT and Harvard, Cambridge Massachusetts, United States of America
- University of Hohenheim, Stuttgart, Germany
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Cecilia M. Lindgren
- Big Data Institute, University of Oxford, Oxford, United Kingdom
- Wellcome Centre for Human Genetics (WCHG), Oxford, United Kingdom
- Broad Institute of MIT and Harvard, Cambridge Massachusetts, United States of America
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Pastel E, Price E, Sjöholm K, McCulloch LJ, Rittig N, Liversedge N, Knight B, Møller N, Svensson PA, Kos K. Lysyl oxidase and adipose tissue dysfunction. Metabolism 2018; 78:118-127. [PMID: 29051043 DOI: 10.1016/j.metabol.2017.10.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 09/01/2017] [Accepted: 10/05/2017] [Indexed: 12/17/2022]
Abstract
BACKGROUND/OBJECTIVES Lysyl oxidase (LOX) is an enzyme crucial for collagen fibre crosslinking and thus for fibrosis development. Fibrosis is characterised by a surplus of collagen fibre accumulation and is amongst others also a feature of obesity-associated dysfunctional adipose tissue (AT) which has been linked with type 2 diabetes. We hypothesised that in type 2 diabetes and obesity LOX expression and activity will be increased as a consequence of worsening AT dysfunction. This study aimed to provide a comprehensive characterisation of LOX in human AT. METHODS LOX mRNA expression was analysed in omental and abdominal subcutaneous AT obtained during elective surgery from subjects with a wide range of BMI, with and without diabetes. In addition, LOX expression was studied in subcutaneous AT before and 9.5months after bariatric surgery. To study the mechanism of LOX changes, its expression and activity were assessed after either hypoxia, recombinant human leptin or glucose treatment of AT explants. In addition, LOX response to acute inflammation was tested after stimulation by a single injection of lipopolysaccharide versus saline solution (control) in healthy men, in vivo. Quantity of mRNA was measured by RT-qPCR. RESULTS LOX expression was higher in obesity and correlated with BMI whilst, in vitro, leptin at high concentrations, as a potential feedback mechanism, suppressed its expression. Neither diabetes status, nor hyperglycaemia affected LOX. Hypoxia and lipopolysaccharide-induced acute inflammation increased LOX AT expression, latter was independent of macrophage infiltration. CONCLUSIONS Whilst LOX may not be affected by obesity-associated complications such as diabetes, our results confirm that LOX is increased by hypoxia and inflammation as underlying mechanism for its upregulation in adipose tissue with obesity.
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Affiliation(s)
- Emilie Pastel
- Diabetes and Obesity Research Group, University of Exeter Medical School, Exeter, UK
| | - Emily Price
- Diabetes and Obesity Research Group, University of Exeter Medical School, Exeter, UK
| | - Kajsa Sjöholm
- Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Laura J McCulloch
- Diabetes and Obesity Research Group, University of Exeter Medical School, Exeter, UK
| | - Nikolaj Rittig
- Department of Internal Medicine and Endocrinology, Aarhus University Hospital, Aarhus, Denmark
| | | | - Bridget Knight
- RD&E NHS Foundation Trust, Exeter, UK; NIHR Exeter Clinical Research Facility, University of Exeter Medical School, Exeter, UK
| | - Niels Møller
- Department of Internal Medicine and Endocrinology, Aarhus University Hospital, Aarhus, Denmark
| | - Per-Arne Svensson
- Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Katarina Kos
- Diabetes and Obesity Research Group, University of Exeter Medical School, Exeter, UK.
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Thorn C, Knight B, Pastel E, McCulloch L, Patel B, Shore A, Kos K. Adipose tissue is influenced by hypoxia of obstructive sleep apnea syndrome independent of obesity. Diabetes & Metabolism 2017; 43:240-247. [DOI: 10.1016/j.diabet.2016.12.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 11/07/2016] [Accepted: 12/01/2016] [Indexed: 12/15/2022]
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Pastel E, Joshi S, Knight B, Liversedge N, Ward R, Kos K. Effects of Exendin-4 on human adipose tissue inflammation and ECM remodelling. Nutr Diabetes 2016; 6:e235. [PMID: 27941938 PMCID: PMC5223133 DOI: 10.1038/nutd.2016.44] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 08/30/2016] [Accepted: 09/14/2016] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND/OBJECTIVES: Subjects with type-2 diabetes are typically obese with dysfunctional adipose tissue (AT). Glucagon-like peptide-1 (GLP-1) analogues are routinely used to improve glycaemia. Although, they also aid weight loss that improves AT function, their direct effect on AT function is unclear. To explore GLP-1 analogues' influence on human AT's cytokine and extracellular matrix (ECM) regulation, we therefore obtained and treated omental (OMAT) and subcutaneous (SCAT) AT samples with Exendin-4, an agonist of the GLP-1 receptor (GLP-1R). SUBJECTS/METHODS: OMAT and abdominal SCAT samples obtained from women during elective surgery at the Royal Devon & Exeter Hospital (UK) were treated with increasing doses of Exendin-4. Changes in RNA expression of adipokines, inflammatory cytokines, ECM components and their regulators were assessed and protein secretion analysed by ELISA. GLP-1R protein accumulation was compared in paired AT depot samples. RESULTS: Exendin-4 induced an increase in OMAT adiponectin (P=0.02) and decrease in elastin expression (P=0.03) in parallel with reduced elastin secretion (P=0.04). In contrast to OMAT, we did not observe an effect on SCAT. There was no change in the expression of inflammatory markers (CD14, TNFA, MCP-1), collagens, TGFB1 or CTGF. GLP-1R accumulation was higher in SCAT. CONCLUSIONS: Independently of weight loss, which may bias findings of in vivo studies, GLP-1 analogues modify human OMAT physiology favourably by increasing the insulin-sensitising cytokine adiponectin. However, the reduction of elastin and no apparent effect on AT's inflammatory cytokines suggest that GLP-1 analogues may be less beneficial to AT function, especially if there is no associated weight loss.
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Affiliation(s)
- E Pastel
- Diabetes and Obesity Research Group, University of Exeter Medical School, Exeter, UK
| | - S Joshi
- Diabetes and Obesity Research Group, University of Exeter Medical School, Exeter, UK
| | - B Knight
- NIHR Exeter Clinical Research Facility, University of Exeter Medical School, Exeter, UK.,RD&E NHS Foundation trust, Exeter, UK
| | | | - R Ward
- Diabetes and Obesity Research Group, University of Exeter Medical School, Exeter, UK
| | - K Kos
- Diabetes and Obesity Research Group, University of Exeter Medical School, Exeter, UK
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Abstract
Aldose reductase (AKR1B) proteins are monomeric enzymes, belonging to the aldo-keto reductase (AKR) superfamily. They perform oxidoreduction of carbonyl groups from a wide variety of substrates, such as aliphatic and aromatic aldehydes or ketones. Due to the involvement of human aldose reductases in pathologies, such as diabetic complications and cancer, AKR1B subgroup enzymatic properties have been extensively characterized. However, the issue of AKR1B function in non-pathologic conditions remains poorly resolved. Adrenal activities generated large amount of harmful aldehydes from lipid peroxidation and steroidogenesis, including 4-hydroxynonenal (4-HNE) and isocaproaldehyde (4-methylpentanal), which can both be reduced by AKR1B proteins. More recently, some AKR1B isoforms have been shown to be endowed with prostaglandin F synthase (PGFS) activity, suggesting that, in addition to possible scavenger function, they could instigate paracrine signals. Interestingly, the adrenal gland is one of the major sites for human and murine AKR1B expression, suggesting that their detoxifying/signaling activity could be specifically required for the correct handling of adrenal function. Moreover, chronic effects of ACTH result in a coordinated regulation of genes encoding the steroidogenic enzymes and some AKR1B isoforms. This review presents the molecular mechanisms accounting for the adrenal-specific expression of some AKR1B genes. Using data from recent mouse genetic models, we will try to connect their enzymatic properties and regulation with adrenal functions.
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Affiliation(s)
- Emilie Pastel
- Diabetes and Obesity Research Group, University of Exeter Medical School, Exeter, UK
| | - Jean-Christophe Pointud
- CNRS, UMR 6293/INSERM U1103, Génétique, Reproduction et Développement, Clermont Université, Aubière, France
| | - Antoine Martinez
- CNRS, UMR 6293/INSERM U1103, Génétique, Reproduction et Développement, Clermont Université, Aubière, France
| | - A. Marie Lefrançois-Martinez
- CNRS, UMR 6293/INSERM U1103, Génétique, Reproduction et Développement, Clermont Université, Aubière, France
- *Correspondence: A. Marie Lefrançois-Martinez,
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Pastel E, Pointud JC, Loubeau G, Dani C, Slim K, Martin G, Volat F, Sahut-Barnola I, Val P, Martinez A, Lefrançois-Martinez AM. Aldose reductases influence prostaglandin F2α levels and adipocyte differentiation in male mouse and human species. Endocrinology 2015; 156:1671-84. [PMID: 25730106 DOI: 10.1210/en.2014-1750] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Aldose reductases (AKR1B) are widely expressed oxidoreductases whose physiological function remains elusive. Some isoforms are genuine prostaglandin F2α (PGF2α) synthases, suggesting they might influence adipose homeostasis because PGF2α inhibits adipogenesis. This was shown by Akr1b7 gene ablation in the mouse, which resulted in increased adiposity related to a lower PGF2α content in fat. Yet humans have no ortholog gene for Akr1b7, so the role of aldose reductases in human adipose homeostasis remains to be explored. We analyzed expression of genes encoding human and mouse aldose reductase isoforms in adipose tissues and differentiating adipocytes to assess conserved mechanisms regulating PGF2α synthesis and adipogenesis. The Akr1b3 gene encoded the most abundant isoform in mouse adipose tissue, whereas Akr1b7 encoded the only isoform enriched in the stromal vascular fraction. Most mouse aldose reductase gene expression peaked in early adipogenesis of 3T3-L1 cells and diminished with differentiation. In contrast with its mouse ortholog Akr1b3, AKR1B1 expression increased throughout differentiation of human multipotent adipose-derived stem cells, paralleling PGF2α release, whereas PGF2α receptor (FP) levels collapsed in early differentiation. Pharmacological inhibition of aldose reductase using Statil altered PGF2α production and enhanced human multipotent adipose-derived stem adipocyte differentiation. As expected, the adipogenic effects of Statil were counteracted by an FP agonist (cloprostenol). Thus, in both species aldose reductase-dependent PGF2α production could be important in early differentiation to restrict adipogenesis. PGF2α antiadipogenic signaling could then be toned down through the FP receptor or aldose reductases down-regulation in human and mouse cells, respectively. Our data suggest that aldose reductase inhibitors could have obesogenic potential.
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Affiliation(s)
- Emilie Pastel
- Centre National de la Recherche Scientifique Unité Mixte de Recherche 6293 (E.P., J.-C.P., G.L., I.S.-B., P.V., A.M., A.-M.L.-M.), INSERM Unité 1103, Génétique Reproduction et Développement, Clermont Université, 63171 Aubière, France; iBV (C.D.), Institute of Biology Valrose, Université Nice Sophia Antipolis, 06189 Nice, France; Service de Chirurgie Digestive (K.S., G.M.), Centre Hospitalier Universitaire Estaing, 63003 Clermont-Ferrand, France; and INSERM Unité Mixte de Recherche 1048 (F.V.), Institute of Metabolic and Cardiovascular Diseases, Université Paul Sabatier, 31432 Toulouse, France
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Volat FE, Pointud JC, Pastel E, Morio B, Sion B, Hamard G, Guichardant M, Colas R, Lefrançois-Martinez AM, Martinez A. Depressed levels of prostaglandin F2α in mice lacking Akr1b7 increase basal adiposity and predispose to diet-induced obesity. Diabetes 2012; 61:2796-806. [PMID: 22851578 PMCID: PMC3478517 DOI: 10.2337/db11-1297] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Negative regulators of white adipose tissue (WAT) expansion are poorly documented in vivo. Prostaglandin F(2α) (PGF(2α)) is a potent antiadipogenic factor in cultured preadipocytes, but evidence for its involvement in physiological context is lacking. We previously reported that Akr1b7, an aldo-keto reductase enriched in adipose stromal vascular fraction but absent from mature adipocytes, has antiadipogenic properties possibly supported by PGF(2α) synthase activity. To test whether lack of Akr1b7 could influence WAT homeostasis in vivo, we generated Akr1b7(-/-) mice in 129/Sv background. Akr1b7(-/-) mice displayed excessive basal adiposity resulting from adipocyte hyperplasia/hypertrophy and exhibited greater sensitivity to diet-induced obesity. Following adipose enlargement and irrespective of the diet, they developed liver steatosis and progressive insulin resistance. Akr1b7 loss was associated with decreased PGF(2α) WAT contents. Cloprostenol (PGF(2α) agonist) administration to Akr1b7(-/-) mice normalized WAT expansion by affecting both de novo adipocyte differentiation and size. Treatment of 3T3-L1 adipocytes and Akr1b7(-/-) mice with cloprostenol suggested that decreased adipocyte size resulted from inhibition of lipogenic gene expression. Hence, Akr1b7 is a major regulator of WAT development through at least two PGF(2α)-dependent mechanisms: inhibition of adipogenesis and lipogenesis. These findings provide molecular rationale to explore the status of aldo-keto reductases in dysregulations of adipose tissue homeostasis.
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Affiliation(s)
- Fanny E. Volat
- Centre National de la Recherche Scientifique Unité Mixte de Recherche 6293/Institut National de la Santé et de la Recherche Médicale U1103–Génétique, Reproduction et Développement, Clermont Université, Aubière, France
| | - Jean-Christophe Pointud
- Centre National de la Recherche Scientifique Unité Mixte de Recherche 6293/Institut National de la Santé et de la Recherche Médicale U1103–Génétique, Reproduction et Développement, Clermont Université, Aubière, France
| | - Emilie Pastel
- Centre National de la Recherche Scientifique Unité Mixte de Recherche 6293/Institut National de la Santé et de la Recherche Médicale U1103–Génétique, Reproduction et Développement, Clermont Université, Aubière, France
| | - Béatrice Morio
- Institut National de la Recherche Agronomique Unité Mixte de Recherche 1019, Centre de Recherche en Nutrition Humaine Auvergne, Clermont-Ferrand, France
| | - Benoit Sion
- EA975, Biologie de la Reproduction, Faculté de Médecine, Université d’Auvergne, Clermont-Ferrand, France
| | - Ghislaine Hamard
- Plate-Forme de Recombinaison Homologue, Institut Cochin, Paris, France
| | - Michel Guichardant
- Institut National de la Santé et de la Recherche Médicale U870, Institut National de la Recherche Agronomique 1235, INSA-Lyon, RMND/Institut Multidisciplinaire de Biochimie des Lipides, Université de Lyon 1, Villeurbanne, France
| | - Romain Colas
- Institut National de la Santé et de la Recherche Médicale U870, Institut National de la Recherche Agronomique 1235, INSA-Lyon, RMND/Institut Multidisciplinaire de Biochimie des Lipides, Université de Lyon 1, Villeurbanne, France
| | - Anne-Marie Lefrançois-Martinez
- Centre National de la Recherche Scientifique Unité Mixte de Recherche 6293/Institut National de la Santé et de la Recherche Médicale U1103–Génétique, Reproduction et Développement, Clermont Université, Aubière, France
| | - Antoine Martinez
- Centre National de la Recherche Scientifique Unité Mixte de Recherche 6293/Institut National de la Santé et de la Recherche Médicale U1103–Génétique, Reproduction et Développement, Clermont Université, Aubière, France
- Corresponding author: Antoine Martinez,
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Pastel E, Pointud JC, Volat F, Martinez A, Lefrançois-Martinez AM. Aldo-Keto Reductases 1B in Endocrinology and Metabolism. Front Pharmacol 2012; 3:148. [PMID: 22876234 PMCID: PMC3410611 DOI: 10.3389/fphar.2012.00148] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Accepted: 07/11/2012] [Indexed: 01/10/2023] Open
Abstract
The aldose reductase (AR; human AKR1B1/mouse Akr1b3) has been the focus of many research because of its role in diabetic complications. The starting point of these alterations is the massive entry of glucose in polyol pathway where it is converted into sorbitol by this enzyme. However, the issue of AR function in non-diabetic condition remains unresolved. AR-like enzymes (AKR1B10, Akr1b7, and Akr1b8) are highly related isoforms often co-expressed with bona fide AR, making functional analysis of one or the other isoform a challenging task. AKR1B/Akr1b members share at least 65% protein identity and the general ability to reduce many redundant substrates such as aldehydes provided from lipid peroxidation, steroids and their by-products, and xenobiotics in vitro. Based on these properties, AKR1B/Akr1b are generally considered as detoxifying enzymes. Considering that divergences should be more informative than similarities to help understanding their physiological functions, we chose to review specific hallmarks of each human/mouse isoforms by focusing on tissue distribution and specific mechanisms of gene regulation. Indeed, although the AR shows ubiquitous expression, AR-like proteins exhibit tissue-specific patterns of expression. We focused on three organs where certain isoforms are enriched, the adrenal gland, enterohepatic, and adipose tissues and tried to connect recent enzymatic and regulation data with endocrine and metabolic functions of these organs. We presented recent mouse models showing unsuspected physiological functions in the regulation of glucido-lipidic metabolism and adipose tissue homeostasis. Beyond the widely accepted idea that AKR1B/Akr1b are detoxification enzymes, these recent reports provide growing evidences that they are able to modify or generate signal molecules. This conceptually shifts this class of enzymes from unenviable status of scavenger to upper class of messengers.
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Affiliation(s)
- Emilie Pastel
- CNRS, UMR6293/INSERM U1103, Génétique, Reproduction et Développement, Clermont Université Aubière, France
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