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Chen ZY, Panga MJ, Zhang X, Qiao S, Chen S, Appiah C, Zhao Y. Estrogen alleviates liver fibrosis and restores metabolic homeostasis in ovariectomy-induced liver injury and carbon tetrachloride (CCl 4) exposure. Eur J Pharmacol 2024; 978:176774. [PMID: 38936452 DOI: 10.1016/j.ejphar.2024.176774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 06/17/2024] [Accepted: 06/23/2024] [Indexed: 06/29/2024]
Abstract
AIM Given estrogen's recognized regulatory influence on diverse metabolic and immune functions, this study sought to explore its potential impact on fibrosis and elucidate the underlying metabolic regulations. METHODS Female mice underwent ovary removal surgery, followed by carbon tetrachloride (CCl4) administration to induce liver injury. Biochemical index analysis and histopathological examination were then conducted. The expression levels of alpha-smooth muscle actin (α-SMA), transforming growth factor-β (TGF-β), and collagen type 1 alpha 1 chain (COL1A1) were assessed using western blotting to further elucidate the extent of liver injury. Finally, metabolite extraction and metabolomic analysis were performed to evaluate metabolic changes. RESULTS Ovary removal exacerbated CCl4-induced liver damage, while estrogen supplementation provided protection against hepatic changes resulting from OVX. Furthermore, estrogen mitigated liver injury induced by CCl4 treatment in vivo. Estrogen supplementation significantly restored liver damage induced by OVX and CCl4. Comparative analysis revealed significant alterations in pathways including aminoacyl-tRNA biosynthesis, glycine, serine, and threonine metabolism, lysine degradation, and taurine and hypotaurine metabolism in estrogen treatment. CONCLUSION Estrogen supplementation alleviates liver injury induced by OVX and CCl4, highlighting its protective effects against fibrosis and associated metabolic alterations.
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Affiliation(s)
- Zi Yi Chen
- School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing, 211800, China
| | - Mogellah John Panga
- School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing, 211800, China
| | - Xiangrui Zhang
- School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing, 211800, China
| | - Shuai Qiao
- School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing, 211800, China
| | - Shitian Chen
- School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing, 211800, China
| | - Clara Appiah
- School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing, 211800, China
| | - Ye Zhao
- School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing, 211800, China.
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2
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Elnegaard JJ, Iena FM, Herold J, Lebeck J. Sex-specific effect of AQP9 deficiency on hepatic triglyceride metabolism in mice with diet-induced obesity. J Physiol 2024; 602:3131-3149. [PMID: 37026573 DOI: 10.1113/jp284188] [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: 02/17/2023] [Accepted: 04/04/2023] [Indexed: 04/08/2023] Open
Abstract
Studies in obese rats and human cell models of non-alcoholic fatty liver disease have indicated that knockdown of the hepatic glycerol channel aquaporin 9 (AQP9) leads to decreased hepatic steatosis. However, a study in leptin receptor-deficient mice did not find that knockout (KO) of AQP9 alleviated hepatic steatosis. The aim of this study was to investigate the effect of high-fat diet (HFD) on hepatic glycerol and triglyceride metabolism in male and female AQP9 KO mice. Male and female AQP9 KO mice and wild-type (WT) littermates were fed a HFD for 12 weeks. Weight, food intake and blood glucose were monitored throughout the study and tissue analysis included determination of hepatic triglyceride content and triglyceride secretion. The expression of key molecules for hepatic glycerol and triglyceride metabolism was evaluated using qPCR and western blotting. AQP9 KO and WT mice demonstrated a similar weight gain throughout the study period, and we found no evidence for AQP9 deficiency being associated with a reduced hepatic accumulation of triglyceride or a reduced blood glucose level. Instead, we show that the effect of AQP9 deficiency on hepatic lipid metabolism is sex-specific, with only male AQP9 KO mice having a reduced hepatic secretion of triglycerides and an elevated expression of peroxisome proliferator-activated receptor α. Male AQP9 KO mice had an elevated blood glucose level after 12 weeks of HFD when compared to baseline levels. Thus, we found no evidence for AQP9 inhibition being a target for alleviating the development of hepatic steatosis in mice with diet-induced obesity. KEY POINTS: This study investigates the effect of AQP9 deficiency on hepatic triglyceride metabolism in both male and female mice fed a high-fat diet (HFD) for 12 weeks. No evidence was found for AQP9 deficiency being associated with a reduced hepatic accumulation of triglyceride or a reduced blood glucose level. The effect of AQP9 deficiency on hepatic triglyceride metabolism is sex-specific. Male AQP9 KO mice had a reduced hepatic secretion of triglycerides and an elevated expression of peroxisome proliferator-activated receptor α, which likely promotes an increased hepatic fatty acid oxidation. Male AQP9 KO had an elevated blood glucose level after 12 weeks of HFD when compared to baseline levels.
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Affiliation(s)
| | | | | | - Janne Lebeck
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
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3
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Localization of aquaglyceroporins in human and murine white adipose tissue. Histochem Cell Biol 2022; 157:623-639. [PMID: 35235046 DOI: 10.1007/s00418-022-02090-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/11/2022] [Indexed: 11/04/2022]
Abstract
The glycerol channel AQP7 facilitates glycerol efflux from adipose tissue (AT), and AQP7 deficiency has been suggested to promote obesity. However, the release of glycerol from AT is not fully blocked in AQP7-deficient mice, which suggests that either alternative glycerol channels are present in AT or significant simple diffusion of glycerol occurs. Previous investigations of the expression of other aquaglyceroporins (AQP3, AQP9, AQP10) than AQP7 in AT are contradictory. Therefore, we here aim at determining the cellular localization of AQP3 and AQP9 in addition to AQP7 in human and mouse AT using well-characterized antibodies for immunohistochemistry (IHC) and immunoblotting as well as available single-cell transcriptomic data from human and mouse AT. We confirm that AQP7 is expressed in endothelial cells and adipocytes in human AT and find ex vivo evidence for interaction between AQP7 and perilipin-1 in adipocytes. In addition, labeling for AQP7 in human AT also includes CD68-positive cells. No labeling for AQP3 or AQP9 was identified in endothelial cells or adipocytes in human or mouse AT using IHC. Instead, in human AT, AQP3 was predominantly found in erythrocytes, whereas AQP9 expression was observed in a small number of CD15-positive cells. The transcriptomic data revealed that AQP3 mRNA was found in a low number of cells in most of the identified cell clusters, whereas AQP9 mRNA was found in myeloid cell clusters as well as in clusters likely representing mesothelial progenitor cells. No AQP10 mRNA was identified in human AT. In conclusion, the presented results do not suggest a functional overlap between AQP3/AQP9/AQP10 and AQP7 in human or mouse white AT.
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4
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Unraveling Human AQP5-PIP Molecular Interaction and Effect on AQP5 Salivary Glands Localization in SS Patients. Cells 2021; 10:cells10082108. [PMID: 34440877 PMCID: PMC8391295 DOI: 10.3390/cells10082108] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 08/11/2021] [Accepted: 08/14/2021] [Indexed: 12/16/2022] Open
Abstract
Saliva secretion requires effective translocation of aquaporin 5 (AQP5) water channel to the salivary glands (SGs) acinar apical membrane. Patients with Sjögren’s syndrome (SS) display abnormal AQP5 localization within acinar cells from SGs that correlate with sicca manifestation and glands hypofunction. Several proteins such as Prolactin-inducible protein (PIP) may regulate AQP5 trafficking as observed in lacrimal glands from mice. However, the role of the AQP5-PIP complex remains poorly understood. In the present study, we show that PIP interacts with AQP5 in vitro and in mice as well as in human SGs and that PIP misexpression correlates with an altered AQP5 distribution at the acinar apical membrane in PIP knockout mice and SS hMSG. Furthermore, our data show that the protein-protein interaction involves the AQP5 C-terminus and the N-terminal of PIP (one molecule of PIP per AQP5 tetramer). In conclusion, our findings highlight for the first time the role of PIP as a protein controlling AQP5 localization in human salivary glands but extend beyond due to the PIP-AQP5 interaction described in lung and breast cancers.
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5
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Salvoza NC, Giraudi PJ, Tiribelli C, Rosso N. Sex differences in non-alcoholic fatty liver disease: hints for future management of the disease. EXPLORATION OF MEDICINE 2020. [DOI: 10.37349/emed.2020.00005] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) remains a major cause of chronic liver disease worldwide. Despite extensive studies, the heterogeneity of the risk factors as well as different disease mechanisms complicate the goals toward effective diagnosis and management. Recently, it has been shown that sex differences play a role in the prevalence and progression of NAFLD. In vitro, in vivo, and clinical studies revealed that the lower prevalence of NAFLD in premenopausal as compared to postmenopausal women and men is mainly due to the protective effects of estrogen and body fat distribution. It has been also described that males and females present differential pathogenic features in terms of biochemical profiles and histological characteristics. However, the exact molecular mechanisms for the gender differences that exist in the pathogenesis of NAFLD are still elusive. Lipogenesis, oxidative stress, and inflammation play a key role in the progression of NAFLD. For NAFLD, only a few studies characterized these mechanisms at the molecular level. Therefore, we aim to review the reported differential molecular mechanisms that trigger such different pathogenesis in both sexes. Differences in lipid metabolism, glucose homeostasis, oxidative stress, inflammation, and fibrosis were discussed based on the evidence reported in recent publications. In conclusion, with this review, we hope to provide a new perspective for the development of future practice guidelines as well as a new avenue for the management of the disease.
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Affiliation(s)
- Noel C. Salvoza
- Fondazione Italiana Fegato ONLUS, Area Science Park Basovizza SS14 km 163.5, 34149 Trieste, Italy; Philippine Council for Health Research and Development, DOST Compound, Bicutan Taguig City 1631, Philippines
| | - Pablo J. Giraudi
- Fondazione Italiana Fegato ONLUS, Area Science Park Basovizza SS14 km 163.5, 34149 Trieste, Italy
| | - Claudio Tiribelli
- Fondazione Italiana Fegato ONLUS, Area Science Park Basovizza SS14 km 163.5, 34149 Trieste, Italy
| | - Natalia Rosso
- Fondazione Italiana Fegato ONLUS, Area Science Park Basovizza SS14 km 163.5, 34149 Trieste, Italy
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Iena FM, Jul JB, Vegger JB, Lodberg A, Thomsen JS, Brüel A, Lebeck J. Sex-Specific Effect of High-Fat Diet on Glycerol Metabolism in Murine Adipose Tissue and Liver. Front Endocrinol (Lausanne) 2020; 11:577650. [PMID: 33193093 PMCID: PMC7609944 DOI: 10.3389/fendo.2020.577650] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 09/30/2020] [Indexed: 12/25/2022] Open
Abstract
Obesity is associated with increased plasma glycerol levels. The coordinated regulation of glycerol channels in adipose tissue (AQP7) and the liver (AQP9) has been suggested as an important contributor to the pathophysiology of type-2-diabetes mellitus, as it would provide glycerol for hepatic synthesis of glucose and triglycerides. The regulation of AQP7 and AQP9 is influenced by sex. This study investigates the effect of a high-fat diet (HFD) on glycerol metabolism in mice and the influence of sex and GLP-1-receptor agonist treatment. Female and male C57BL/6JRj mice were fed either a control diet or a HFD for 12 or 24 weeks. Liraglutide was administered (1 mg/kg/day) to a subset of female mice. After 12 weeks of HFD, females had gained less weight than males. In adipose tissue, only females demonstrated an increased abundance of AQP7, whereas only males demonstrated a significant increase in glycerol kinase abundance and adipocyte size. 24 weeks of HFD resulted in a more comparable effect on weight gain and adipose tissue in females and males. HFD resulted in marked hepatic steatosis in males only and had no significant effect on the hepatic abundance of AQP9. Liraglutide treatment generally attenuated the effects of HFD on glycerol metabolism. In conclusion, no coordinated upregulation of glycerol channels in adipose tissue and liver was observed in response to HFD. The effect of HFD on glycerol metabolism is sex-specific in mice, and we propose that the increased AQP7 abundance in female adipose tissue could contribute to their less severe response to HFD.
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7
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Ikarashi N, Nagoya C, Kon R, Kitaoka S, Kajiwara S, Saito M, Kawabata A, Ochiai W, Sugiyama K. Changes in the Expression of Aquaporin-3 in the Gastrointestinal Tract Affect Drug Absorption. Int J Mol Sci 2019; 20:ijms20071559. [PMID: 30925715 PMCID: PMC6479729 DOI: 10.3390/ijms20071559] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 03/25/2019] [Accepted: 03/26/2019] [Indexed: 02/07/2023] Open
Abstract
Aquaporin-3 (AQP3) plays an important role in water transport in the gastrointestinal (GI) tract. In this study, we conducted a Caco-2 cell permeability assay to examine how changes in the expression and function of AQP3 affect the rate at which a drug is absorbed via passive transport in the GI tract. When the function of AQP3 was inhibited by mercuric chloride or phloretin, there was no change in warfarin permeability. In contrast, when the expression of AQP3 protein was decreased by prostaglandin E₂ (PGE₂) treatment, warfarin permeability increased to approximately twice the control level, and membrane fluidity increased by 15%. In addition, warfarin permeability increased to an extent comparable to that after PGE₂ treatment when cell membrane fluidity was increased by 10% via boric acid/EDTA treatment. These findings suggest the possibility that the increased drug absorption under decreased AQP3 expression was attributable to increased membrane fluidity. The results of this study demonstrate that the rate of water transport has little effect on drug absorption. However, our findings also indicate that although AQP3 and other similar transmembrane proteins do not themselves transport drugs, changes in their expression levels can cause changes in cell membrane fluidity, thus affecting drug absorption rates.
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Affiliation(s)
- Nobutomo Ikarashi
- Department of Biomolecular Pharmacology, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan.
| | - Chika Nagoya
- Department of Clinical Pharmacokinetics, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan.
| | - Risako Kon
- Department of Biomolecular Pharmacology, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan.
| | - Satoshi Kitaoka
- Department of Clinical Pharmacokinetics, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan.
| | - Sayuri Kajiwara
- Department of Clinical Pharmacokinetics, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan.
| | - Masayo Saito
- Department of Clinical Pharmacokinetics, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan.
| | - Akane Kawabata
- Department of Clinical Pharmacokinetics, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan.
| | - Wataru Ochiai
- Department of Clinical Pharmacokinetics, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan.
| | - Kiyoshi Sugiyama
- Department of Functional Molecular Kinetics, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan.
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Estrogen Modulates Glycerol Permeability in Sertoli Cells through Downregulation of Aquaporin-9. Cells 2018; 7:cells7100153. [PMID: 30274223 PMCID: PMC6211071 DOI: 10.3390/cells7100153] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 09/24/2018] [Accepted: 09/27/2018] [Indexed: 12/22/2022] Open
Abstract
High 17β-Estradiol (E2) levels are known to cause alterations of spermatogenesis and environments throughout the male reproductive tract. Sertoli cells (SCs) ensure an adequate environment inside the seminiferous tubule. Glycerol stands as essential for the maintenance of blood⁻testis barrier created by SCs, however, the role of E2 in this process is not known. Herein, we hypothesized that the effect of E2 on glycerol permeability in mouse SCs (mSCs) could be mediated by aquaglyceroporins. The expression of aquaglyceroporins was assessed by RT-PCR and qRT-PCR. Glycerol permeability was evaluated by stopped-flow light scattering. We were able to identify the expression of AQP3 and AQP9 in mSCs where AQP9 is more abundant than AQP3. Our results show that high E2 levels decrease AQP9 mRNA abundance with no influence on AQP3 in mSCs. Interestingly, high E2 levels decreased mSCs' permeability to glycerol, while downregulating AQP9 expression, thus suggesting a novel mechanism by which E2 modulates fluid secretion in the testis. In conclusion, E2 is an important regulator of mSCs physiology and secretion through changes in AQP9 expression and function. Thus, alterations in glycerol permeability induced by E2 may be the cause for male infertility in cases associated with the presence of high E2 levels.
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9
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Calamita G, Perret J, Delporte C. Aquaglyceroporins: Drug Targets for Metabolic Diseases? Front Physiol 2018; 9:851. [PMID: 30042691 PMCID: PMC6048697 DOI: 10.3389/fphys.2018.00851] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 06/15/2018] [Indexed: 12/29/2022] Open
Abstract
Aquaporins (AQPs) are a family of transmembrane channel proteins facilitating the transport of water, small solutes, and gasses across biological membranes. AQPs are expressed in all tissues and ensure multiple roles under normal and pathophysiological conditions. Aquaglyceroporins are a subfamily of AQPs permeable to glycerol in addition to water and participate thereby to energy metabolism. This review focalizes on the present knowledge of the expression, regulation and physiological roles of AQPs in adipose tissue, liver and endocrine pancreas, that are involved in energy metabolism. In addition, the review aims at summarizing the involvement of AQPs in metabolic disorders, such as obesity, diabetes and liver diseases. Finally, challenges and recent advances related to pharmacological modulation of AQPs expression and function to control and treat metabolic diseases are discussed.
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Affiliation(s)
- Giuseppe Calamita
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari Aldo Moro, Bari, Italy
| | - Jason Perret
- Laboratory of Pathophysiological and Nutritional Biochemistry, Université Libre de Bruxelles, Brussels, Belgium
| | - Christine Delporte
- Laboratory of Pathophysiological and Nutritional Biochemistry, Université Libre de Bruxelles, Brussels, Belgium
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da Silva IV, Rodrigues JS, Rebelo I, Miranda JPG, Soveral G. Revisiting the metabolic syndrome: the emerging role of aquaglyceroporins. Cell Mol Life Sci 2018; 75:1973-1988. [PMID: 29464285 PMCID: PMC11105723 DOI: 10.1007/s00018-018-2781-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 02/05/2018] [Accepted: 02/15/2018] [Indexed: 02/07/2023]
Abstract
The metabolic syndrome (MetS) includes a group of medical conditions such as insulin resistance (IR), dyslipidemia and hypertension, all associated with an increased risk for cardiovascular disease. Increased visceral and ectopic fat deposition are also key features in the development of IR and MetS, with pathophysiological sequels on adipose tissue, liver and muscle. The recent recognition of aquaporins (AQPs) involvement in adipose tissue homeostasis has opened new perspectives for research in this field. The members of the aquaglyceroporin subfamily are specific glycerol channels implicated in energy metabolism by facilitating glycerol outflow from adipose tissue and its systemic distribution and uptake by liver and muscle, unveiling these membrane channels as key players in lipid balance and energy homeostasis. Being involved in a variety of pathophysiological mechanisms including IR and obesity, AQPs are considered promising drug targets that may prompt novel therapeutic approaches for metabolic disorders such as MetS. This review addresses the interplay between adipose tissue, liver and muscle, which is the basis of the metabolic syndrome, and highlights the involvement of aquaglyceroporins in obesity and related pathologies and how their regulation in different organs contributes to the features of the metabolic syndrome.
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Affiliation(s)
- Inês Vieira da Silva
- Faculty of Pharmacy, Research Institute for Medicines (iMed.ULisboa), Universidade de Lisboa, 1649-003, Lisbon, Portugal
- Department of Biochemistry and Human Biology, Faculty of Pharmacy, Universidade de Lisboa, 1649-003, Lisbon, Portugal
| | - Joana S Rodrigues
- Faculty of Pharmacy, Research Institute for Medicines (iMed.ULisboa), Universidade de Lisboa, 1649-003, Lisbon, Portugal
- Department of Toxicological and Bromatological Sciences, Faculty of Pharmacy, Universidade de Lisboa, 1649-003, Lisbon, Portugal
| | - Irene Rebelo
- UCIBIO, REQUIMTE, Department of Biological Sciences, Faculty of Pharmacy, Universidade do Porto, Porto, Portugal
| | - Joana P G Miranda
- Faculty of Pharmacy, Research Institute for Medicines (iMed.ULisboa), Universidade de Lisboa, 1649-003, Lisbon, Portugal
- Department of Toxicological and Bromatological Sciences, Faculty of Pharmacy, Universidade de Lisboa, 1649-003, Lisbon, Portugal
| | - Graça Soveral
- Faculty of Pharmacy, Research Institute for Medicines (iMed.ULisboa), Universidade de Lisboa, 1649-003, Lisbon, Portugal.
- Department of Biochemistry and Human Biology, Faculty of Pharmacy, Universidade de Lisboa, 1649-003, Lisbon, Portugal.
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Winterbottom EF, Koestler DC, Fei DL, Wika E, Capobianco AJ, Marsit CJ, Karagas MR, Robbins DJ. The aquaglyceroporin AQP9 contributes to the sex-specific effects of in utero arsenic exposure on placental gene expression. Environ Health 2017; 16:59. [PMID: 28615018 PMCID: PMC5471920 DOI: 10.1186/s12940-017-0267-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 06/06/2017] [Indexed: 05/22/2023]
Abstract
BACKGROUND Sex-specific factors play a major role in human health and disease, including responses to environmental stresses such as toxicant exposure. Increasing evidence suggests that such sex differences also exist during fetal development. In a previous report using the resources of the New Hampshire Birth Cohort Study (NHBCS), we found that low-to-moderate in utero exposure to arsenic, a highly toxic and widespread pollutant, was associated with altered expression of several key developmental genes in the fetal portion of the placenta. These associations were sex-dependent, suggesting that in utero arsenic exposure differentially impacts male and female fetuses. In the present study, we investigated the molecular basis for these sex-specific responses to arsenic. METHODS Using NanoString technology, we further analyzed the fetal placenta samples from the NHBCS for the expression of genes encoding arsenic transporters and metabolic enzymes. Multivariable linear regression analysis was used to examine their relationship with arsenic exposure and with key developmental genes, after stratification by fetal sex. RESULTS We found that maternal arsenic exposure was strongly associated with expression of the AQP9 gene, encoding an aquaglyceroporin transporter, in female but not male fetal placenta. Moreover, AQP9 expression associated with that of a subset of female-specific arsenic-responsive genes. CONCLUSIONS Our results suggest that AQP9 is upregulated in response to arsenic exposure in female, but not male, fetal placenta. Based on these results and prior studies, increased AQP9 expression may lead to increased arsenic transport in the female fetal placenta, which in turn may alter the expression patterns of key developmental genes that we have previously shown to be associated with arsenic exposure. Thus, this study suggests that AQP9 may play a role in the sex-specific effects of in utero arsenic exposure.
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Affiliation(s)
- Emily F. Winterbottom
- Molecular Oncology Program, DeWitt Daughtry Family Department of Surgery, University of Miami Miller School of Medicine, Miami, FL 33136 USA
| | - Devin C. Koestler
- Department of Biostatistics, University of Kansas Medical Center, Kansas City, KS 66160 USA
| | - Dennis Liang Fei
- Molecular Oncology Program, DeWitt Daughtry Family Department of Surgery, University of Miami Miller School of Medicine, Miami, FL 33136 USA
- Department of Pharmacology and Toxicology, Program in Experimental and Molecular Medicine, Geisel School of Medicine at Dartmouth, Hanover, NH 03755 USA
- Current address: Weill Cornell Medicine, New York, NY 10065 USA
| | - Eric Wika
- Department of Biostatistics, University of Kansas Medical Center, Kansas City, KS 66160 USA
| | - Anthony J. Capobianco
- Molecular Oncology Program, DeWitt Daughtry Family Department of Surgery, University of Miami Miller School of Medicine, Miami, FL 33136 USA
- Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL 33136 USA
| | - Carmen J. Marsit
- Department of Environmental Health, Rollins School of Public Health at Emory University, Atlanta, GA 30322 USA
| | - Margaret R. Karagas
- Department of Epidemiology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755 USA
| | - David J. Robbins
- Molecular Oncology Program, DeWitt Daughtry Family Department of Surgery, University of Miami Miller School of Medicine, Miami, FL 33136 USA
- Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL 33136 USA
- Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL 33136 USA
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Tardelli M, Claudel T, Bruschi FV, Moreno-Viedma V, Trauner M. Adiponectin regulates AQP3 via PPARα in human hepatic stellate cells. Biochem Biophys Res Commun 2017; 490:51-54. [PMID: 28595905 DOI: 10.1016/j.bbrc.2017.06.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 06/03/2017] [Indexed: 01/07/2023]
Abstract
Aquaporins (AQPs) are trans-membrane proteins which allow the movement of water and glycerol required by hepatic stellate cells (HSC) for triglyceride formation and lipid storage. Adiponectin (ADPQ) is a hormone produced by the adipose tissue, which is known to increase AQP3 expression. Since ADPQ receptor signals via the nuclear receptor PPAR we aimed to explore the role of this pathway in AQP3 regulation by ADPQ in HSC. AQP3 and CPT1α expression increased only after ADPQ but not rosiglitazone stimulation. In LX2 cells co-transfected with plasmids expressing PPARα or PPARγ coupled to a luciferase reporter gene, only PPARα increased luciferase activity after ADPQ stimulation. Collectively, our findings demonstrate that ADPQ increases AQP3 expression through PPARα-mediated signaling in HSC.
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Affiliation(s)
- Matteo Tardelli
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology & Hepatology, Internal Medicine III, Medical University of Vienna, Austria
| | - Thierry Claudel
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology & Hepatology, Internal Medicine III, Medical University of Vienna, Austria
| | - Francesca V Bruschi
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology & Hepatology, Internal Medicine III, Medical University of Vienna, Austria
| | - Veronica Moreno-Viedma
- Institute of Cancer Research, Department of Medicine I, Comprehensive Cancer Center, Medical University of Vienna, Austria
| | - Michael Trauner
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology & Hepatology, Internal Medicine III, Medical University of Vienna, Austria.
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Wawrzkiewicz-Jałowiecka A, Kowalczyk K, Pluta D, Blukacz Ł, Madej P. The role of aquaporins in polycystic ovary syndrome - A way towards a novel drug target in PCOS. Med Hypotheses 2017; 102:23-27. [PMID: 28478824 DOI: 10.1016/j.mehy.2017.03.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 03/05/2017] [Indexed: 11/25/2022]
Abstract
Aquaporins (AQPs) are transmembrane proteins, able to transport water (and in some cases also small solutes, e. g. glycerol) through the cell membrane. There are twelve types of aquaporins (AQP1-AQP12) expressed in mammalian reproductive systems. According to literature, many diseases of the reproductive organs are correlated with changes of AQPs expression and their malfunction. That is the case in the polycystic ovary syndrome (PCOS), where dysfunctions of AQPs 7-9 and alterations in its levels occur. In this work, we postulate how AQPs are involved in PCOS-related disorders, in order to emphasize their potential therapeutic meaning as a drug target. Our research allows for a surprising inference, that genetic mutation causing malfunction and/or decreased expression of aquaporins, may be incorporated in the popular insulin-dependent hypothesis of PCOS pathogenesis. What is more, changes in AQP's expression may affect the folliculogenesis and follicular atresia in PCOS.
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Affiliation(s)
- Agata Wawrzkiewicz-Jałowiecka
- Department of Physical Chemistry and Technology of Polymers, Faculty of Chemistry, Silesian University of Technology, 44-100 Gliwice, Ks. M. Strzody 9, Poland.
| | - Karolina Kowalczyk
- Department of Gynecological Endocrinology, Medical Faculty in Katowice, Medical University of Silesia, 40-752 Katowice, Poland
| | - Dagmara Pluta
- Department of Gynecological Endocrinology, Medical Faculty in Katowice, Medical University of Silesia, 40-752 Katowice, Poland
| | - Łukasz Blukacz
- Department of Gynecological Endocrinology, Medical Faculty in Katowice, Medical University of Silesia, 40-752 Katowice, Poland
| | - Paweł Madej
- Department of Gynecological Endocrinology, Medical Faculty in Katowice, Medical University of Silesia, 40-752 Katowice, Poland
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Bernardino RL, Marinelli RA, Maggio A, Gena P, Cataldo I, Alves MG, Svelto M, Oliveira PF, Calamita G. Hepatocyte and Sertoli Cell Aquaporins, Recent Advances and Research Trends. Int J Mol Sci 2016; 17:ijms17071096. [PMID: 27409609 PMCID: PMC4964472 DOI: 10.3390/ijms17071096] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2016] [Revised: 06/22/2016] [Accepted: 07/04/2016] [Indexed: 12/30/2022] Open
Abstract
Aquaporins (AQPs) are proteinaceous channels widespread in nature where they allow facilitated permeation of water and uncharged through cellular membranes. AQPs play a number of important roles in both health and disease. This review focuses on the most recent advances and research trends regarding the expression and modulation, as well as physiological and pathophysiological functions of AQPs in hepatocytes and Sertoli cells (SCs). Besides their involvement in bile formation, hepatocyte AQPs are involved in maintaining energy balance acting in hepatic gluconeogenesis and lipid metabolism, and in critical processes such as ammonia detoxification and mitochondrial output of hydrogen peroxide. Roles are played in clinical disorders including fatty liver disease, diabetes, obesity, cholestasis, hepatic cirrhosis and hepatocarcinoma. In the seminiferous tubules, particularly in SCs, AQPs are also widely expressed and seem to be implicated in the various stages of spermatogenesis. Like in hepatocytes, AQPs may be involved in maintaining energy homeostasis in these cells and have a major role in the metabolic cooperation established in the testicular tissue. Altogether, this information represents the mainstay of current and future investigation in an expanding field.
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Affiliation(s)
- Raquel L Bernardino
- Department of Microscopy, Laboratory of Cell Biology, Institute of Biomedical Sciences Abel Salazar (ICBAS) and Unit for Multidisciplinary Research in Biomedicine (UMIB), University of Porto, 4050-313 Porto, Portugal.
| | - Raul A Marinelli
- Instituto de Fisiología Experimental-CONICET, Facultad de Ciencias Bioquímicas y Farmacéuticas-Universidad Nacional de Rosario, 531 S2002LRK Rosario, Santa Fe, Argentina.
| | - Anna Maggio
- Department of Biosciences, Biotechnologies and Biopharnaceutics, University of Bari "Aldo Moro", 70125 Bari, Italy.
| | - Patrizia Gena
- Department of Biosciences, Biotechnologies and Biopharnaceutics, University of Bari "Aldo Moro", 70125 Bari, Italy.
| | - Ilaria Cataldo
- Department of Biosciences, Biotechnologies and Biopharnaceutics, University of Bari "Aldo Moro", 70125 Bari, Italy.
| | - Marco G Alves
- CICS-UBI, Health Sciences Research Centre, University of Beira Interior, 6201-506 Covilhã, Portugal.
| | - Maria Svelto
- Department of Biosciences, Biotechnologies and Biopharnaceutics, University of Bari "Aldo Moro", 70125 Bari, Italy.
| | - Pedro F Oliveira
- Department of Microscopy, Laboratory of Cell Biology, Institute of Biomedical Sciences Abel Salazar (ICBAS) and Unit for Multidisciplinary Research in Biomedicine (UMIB), University of Porto, 4050-313 Porto, Portugal.
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal.
| | - Giuseppe Calamita
- Department of Biosciences, Biotechnologies and Biopharnaceutics, University of Bari "Aldo Moro", 70125 Bari, Italy.
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15
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Yaussy SL, DeWitte SN, Redfern RC. Frailty and famine: Patterns of mortality and physiological stress among victims of famine in medieval London. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2016; 160:272-83. [DOI: 10.1002/ajpa.22954] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 01/12/2016] [Accepted: 01/16/2016] [Indexed: 11/05/2022]
Affiliation(s)
| | - Sharon N. DeWitte
- Department of AnthropologyUniversity of South CarolinaColumbia SC29208
| | - Rebecca C. Redfern
- Centre for Human Bioarchaeology, Museum of LondonLondonEC2Y 5HN United Kingdom
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16
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Laforenza U, Bottino C, Gastaldi G. Mammalian aquaglyceroporin function in metabolism. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1858:1-11. [PMID: 26456554 DOI: 10.1016/j.bbamem.2015.10.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 10/05/2015] [Accepted: 10/07/2015] [Indexed: 11/26/2022]
Abstract
Aquaglyceroporins are integral membrane proteins that are permeable to glycerol as well as water. The movement of glycerol from a tissue/organ to the plasma and vice versa requires the presence of different aquaglyceroporins that can regulate the entrance or the exit of glycerol across the plasma membrane. Actually, different aquaglyceroporins have been discovered in the adipose tissue, small intestine, liver, kidney, heart, skeletal muscle, endocrine pancreas and capillary endothelium, and their differential expression could be related to obesity and the type 2 diabetes. Here we describe the expression and function of different aquaglyceroporins in physiological condition and in obesity and type 2 diabetes, suggesting they are potential therapeutic targets for metabolic disorders.
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Affiliation(s)
| | - Cinzia Bottino
- Department of Molecular Medicine, University of Pavia, Italy
| | - Giulia Gastaldi
- Department of Molecular Medicine, University of Pavia, Italy
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17
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Spegel P, Chawade A, Nielsen S, Kjellbom P, Rützler M. Deletion of glycerol channel aquaporin-9 (Aqp9) impairs long-term blood glucose control in C57BL/6 leptin receptor-deficient (db/db) obese mice. Physiol Rep 2015; 3:3/9/e12538. [PMID: 26416971 PMCID: PMC4600382 DOI: 10.14814/phy2.12538] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Deletion of the glycerol channel aquaporin-9 (Aqp9) reduces postprandial blood glucose levels in leptin receptor–deficient (db/db) obese mice on a C57BL/6 × C57BLKS mixed genetic background. Furthermore, shRNA-mediated reduction of Aqp9 expression reduces liver triacylglycerol (TAG) accumulation in a diet-induced rat model of obesity. The aim of this study was to investigate metabolic effects of Aqp9 deletion in coisogenic db/db mice of the C57BL/6 background. Aqp9wtdb/db and Aqp9−/−db/db mice did not differ in body weight and liver TAG contents. On the C57BL/6 genetic background, we observed elevated plasma glucose in Aqp9−/−db/db mice (+1.1 mmol/L, life-time average), while plasma insulin concentration was reduced at the time of death. Glucose levels changed similarly in pentobarbital anesthetized, glucagon challenged Aqp9wtdb/db and Aqp9−/−db/db mice. Liver transcriptional profiling did not detect differential gene expression between genotypes. Metabolite profiling revealed a sex independent increase in plasma glycerol (+55%) and glucose (+24%), and reduction in threonate (all at q < 0.1) in Aqp9−/−db/db mice compared to controls. Metabolite profiling thus confirms a role of AQP9 in glycerol metabolism of obese C57BL/6 db/db mice. In this animal model of obesity Aqp9 gene deletion elevates plasma glucose and does not alleviate hepatosteatosis.
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Affiliation(s)
- Peter Spegel
- Unit of Molecular Metabolism, Lund University Diabetes Centre CRC Skåne University Hospital, Malmö, Sweden
| | - Aakash Chawade
- Department of Immunotechnology, Lund University, Lund, Sweden
| | - Søren Nielsen
- Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Per Kjellbom
- Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden
| | - Michael Rützler
- Department of Health Science and Technology, Aalborg University, Aalborg, Denmark Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden
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18
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Lebeck J, Cheema MU, Skowronski MT, Nielsen S, Praetorius J. Hepatic AQP9 expression in male rats is reduced in response to PPARα agonist treatment. Am J Physiol Gastrointest Liver Physiol 2015; 308:G198-205. [PMID: 25477377 DOI: 10.1152/ajpgi.00407.2013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The peroxisome proliferator receptor α (PPARα) is a key regulator of the hepatic response to fasting with effects on both lipid and carbohydrate metabolism. A role in hepatic glycerol metabolism has also been found; however, the results are somewhat contradictive. Aquaporin 9 (AQP9) is a pore-forming transmembrane protein that facilitates hepatic uptake of glycerol. Its expression is inversely regulated by insulin in male rodents, with increased expression during fasting. Previous results indicate that PPARα plays a crucial role in the induction of AQP9 mRNA during fasting. In the present study, we use PPARα agonists to explore the effect of PPARα activation on hepatic AQP9 expression and on the abundance of enzymes involved in glycerol metabolism using both in vivo and in vitro systems. In male rats with free access to food, treatment with the PPARα agonist WY 14643 (3 mg·kg(-1)·day(-1)) caused a 50% reduction in hepatic AQP9 abundance with the effect being restricted to AQP9 expressed in periportal hepatocytes. The pharmacological activation of PPARα had no effect on the abundance of GlyK, whereas it caused an increased expression of hepatic GPD1, GPAT1, and L-FABP protein. In WIF-B9 and HepG2 hepatocytes, both WY 14643 and another PPARα agonist GW 7647 reduced the abundance of AQP9 protein. In conclusion, pharmacological PPARα activation results in a marked reduction in the abundance of AQP9 in periportal hepatocytes. Together with the effect on the enzymatic apparatus for glycerol metabolism, our results suggest that PPARα activation in the fed state directs glycerol into glycerolipid synthesis rather than into de novo synthesis of glucose.
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Affiliation(s)
- Janne Lebeck
- The Danish Diabetes Academy, Aarhus University, Aarhus, Denmark; Department of Biomedicine, Health, Aarhus University, Aarhus, Denmark; and
| | | | - Mariusz T Skowronski
- Department of Animal Physiology, University of Warmia and Mazury, Olsztyn, Poland
| | - Søren Nielsen
- Department of Biomedicine, Health, Aarhus University, Aarhus, Denmark; and
| | - Jeppe Praetorius
- Department of Biomedicine, Health, Aarhus University, Aarhus, Denmark; and
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19
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Rodríguez A, Marinelli RA, Tesse A, Frühbeck G, Calamita G. Sexual Dimorphism of Adipose and Hepatic Aquaglyceroporins in Health and Metabolic Disorders. Front Endocrinol (Lausanne) 2015; 6:171. [PMID: 26594198 PMCID: PMC4633488 DOI: 10.3389/fendo.2015.00171] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 10/26/2015] [Indexed: 12/13/2022] Open
Abstract
Gender differences in the relative risk of developing metabolic complications, such as insulin resistance or non-alcoholic fatty liver disease (NAFLD), have been reported. The deregulation of glycerol metabolism partly contributes to the onset of these metabolic diseases, since glycerol constitutes a key substrate for the synthesis of triacylglycerols (TAGs) as well as for hepatic gluconeogenesis. The present mini-review covers the sex--related differences in glycerol metabolism and aquaglyceroporins (AQPs) and its impact in the control of adipose and hepatic fat accumulation as well as in whole-body glucose homeostasis. Plasma glycerol concentrations are increased in women compared to men probably due to the higher lipolytic rate and larger AQP7 amounts in visceral fat as well as the well-known sexual dimorphism in fat mass with women showing higher adiposity. AQP9 represents the primary route for glycerol uptake in hepatocytes, where glycerol is converted by the glycerol-kinase enzyme into glycerol-3-phosphate, a key substrate for de novo synthesis of glucose and TAG. In spite of showing similar hepatic AQP9 protein, women exhibit lower hepatocyte glycerol permeability than men, which might contribute to their lower prevalence of insulin resistance and NAFLD.
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Affiliation(s)
- Amaia Rodríguez
- Metabolic Research Laboratory, CIBEROBN, IdiSNA, Clínica Universidad de Navarra, Pamplona, Spain
| | - Raul A. Marinelli
- Facultad de Ciencias Bioquímicas y Farmacéuticas, Instituto de Fisiología Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Rosario, Rosario, Argentina
| | - Angela Tesse
- INSERM UMR 1087/CNRS UMR 629, L’Institut du Thorax, IRS-UN, Nantes, France
| | - Gema Frühbeck
- Metabolic Research Laboratory, CIBEROBN, IdiSNA, Clínica Universidad de Navarra, Pamplona, Spain
| | - Giuseppe Calamita
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari “Aldo Moro”, Bari, Italy
- *Correspondence: Giuseppe Calamita,
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20
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Ruiz ML, Mottino AD, Catania VA, Vore M. Hormonal regulation of hepatic drug biotransformation and transport systems. Compr Physiol 2014; 3:1721-40. [PMID: 24265243 DOI: 10.1002/cphy.c130018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The human body is constantly exposed to many xenobiotics including environmental pollutants, food additives, therapeutic drugs, etc. The liver is considered the primary site for drug metabolism and elimination pathways, consisting in uptake, phase I and II reactions, and efflux processes, usually acting in this same order. Modulation of biotransformation and disposition of drugs of clinical application has important therapeutic and toxicological implications. We here provide a compilation and analysis of relevant, more recent literature reporting hormonal regulation of hepatic drug biotransformation and transport systems. We provide additional information on the effect of hormones that tentatively explain differences between sexes. A brief discussion on discrepancies between experimental models and species, as well as a link between gender-related differences and the hormonal mechanism explaining such differences, is also presented. Finally, we include a comment on the pathophysiological, toxicological, and pharmacological relevance of these regulations.
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Affiliation(s)
- María L Ruiz
- Institute of Experimental Physiology, National University of Rosario, Rosario, Argentina
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21
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Abstract
Obesity and secondary development of type 2 diabetes (T2D) are major health care problems throughout the developed world. Accumulating evidence suggest that glycerol metabolism contributes to the pathophysiology of obesity and T2D. Glycerol is a small molecule that serves as an important intermediate between carbohydrate and lipid metabolism. It is stored primarily in adipose tissue as the backbone of triglyceride (TG) and during states of metabolic stress, such as fasting and diabetes, it is released for metabolism in other tissues. In the liver, glycerol serves as a gluconeogenic precursor and it is used for the esterification of free fatty acid into TGs. Aquaporin 7 (AQP7) in adipose tissue and AQP9 in the liver are transmembrane proteins that belong to the subset of AQPs called aquaglyceroporins. AQP7 facilitates the efflux of glycerol from adipose tissue and AQP7 deficiency has been linked to TG accumulation in adipose tissue and adult onset obesity. On the other hand, AQP9 expressed in liver facilitates the hepatic uptake of glycerol and thereby the availability of glycerol for de novo synthesis of glucose and TG that both are involved in the pathophysiology of diabetes. The aim of this review was to summarize the current knowledge on the role of the two glycerol channels in controlling glycerol metabolism in adipose tissue and liver.
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Affiliation(s)
- Janne Lebeck
- The Danish Diabetes Academy, Odense, Denmark Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 3, DK-8000 Aarhus, Denmark
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22
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Reduced hepatic aquaporin-9 and glycerol permeability are related to insulin resistance in non-alcoholic fatty liver disease. Int J Obes (Lond) 2013; 38:1213-20. [PMID: 24418844 DOI: 10.1038/ijo.2013.234] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 11/20/2013] [Accepted: 12/04/2013] [Indexed: 12/26/2022]
Abstract
BACKGROUND/OBJECTIVES Glycerol represents an important metabolite for the control of lipid accumulation and hepatic gluconeogenesis. We investigated whether hepatic expression and functionality of aquaporin-9 (AQP9), a channel mediating glycerol influx into hepatocytes, is impaired in non-alcoholic fatty liver disease (NAFLD) and steatohepatitis (NASH) in the context of insulin resistance. SUBJECTS/METHODS Liver biopsies were obtained from 66 morbid obese patients undergoing bariatric surgery (66% women, mean body mass index (BMI) 46.1±1.0 kg m(-2)) with available liver echography and pathology analysis of the biopsies in this cross-sectional study. Subjects were classified according to normoglycemia (NG), impaired glucose tolerance (IGT) or type 2 diabetes (T2D). Hepatic expression of AQP9 was analyzed by real-time PCR, western blotting and immunohistochemistry, while glycerol permeability (P(gly)) was measured by stopped-flow light scattering. RESULTS AQP9 was the most abundantly (P<0.0001) expressed aquaglyceroporin in human liver (AQP9>>>AQP3>AQP7>AQP10). Obese patients with T2D showed increased plasma glycerol as well as lower P(gly) and hepatic AQP9 expression. The prevalence of NAFLD and NASH in T2D patients was 100 and 65%, respectively. Interestingly, AQP9 expression was decreased in patients with NAFLD and NASH as compared with those without hepatosteatosis, in direct relation to the degree of steatosis and lobular inflammation, being further reduced in insulin-resistant individuals. The association of AQP9 with insulin sensitivity was independent of BMI and age. Consistent with these data, fasting insulin and C-reactive protein contributed independently to 33.1% of the hepatic AQP9 mRNA expression variance after controlling for the effects of age and BMI. CONCLUSIONS AQP9 downregulation together with the subsequent reduction in hepatic glycerol permeability in insulin-resistant states emerges as a compensatory mechanism whereby the liver counteracts further triacylglycerol accumulation within its parenchyma as well as reduces hepatic gluconeogenesis in patients with NAFLD.
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Liver glycerol permeability and aquaporin-9 are dysregulated in a murine model of Non-Alcoholic Fatty Liver Disease. PLoS One 2013; 8:e78139. [PMID: 24205128 PMCID: PMC3813550 DOI: 10.1371/journal.pone.0078139] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Accepted: 09/11/2013] [Indexed: 11/19/2022] Open
Abstract
One form of liver steatosis, namely Non-Alcoholic Fatty Liver Disease (NAFLD), is a worrisome health problem worldwide characterized by intrahepatic triacylglycerol (TG) overaccumulation. NAFLD is a common feature of metabolic syndrome being often associated with obesity, dyslipidemia and diabetes and mostly closely linked to insulin resistance. The mechanism of NAFLD pathogenesis is object of intense investigation especially regarding complex systems ultimately resulting in excessive TG deposition in hepatocytes. However, scarce is the attention about the relevance of hepatic import of glycerol, the other primary source (as glycerol-3-phosphate) of increased TG in hepatocytes. Obese leptin-deficient (ob/ob) mice, an animal model of NAFLD, were used to evaluate the functional involvement of Aquaporin-9 (AQP9), the major pathway of liver glycerol entry, in hepatosteatosis. By RT-PCR and qPCR, the level of Aqp9 mRNA in the liver of starved obese mice was comparable with the corresponding control lean littermates. By immunoblotting, the AQP9 protein at the hepatocyte sinusoidal plasma membrane of obese mice was markedly lower (33%) than lean mice, a finding fully confirmed by immunohistochemistry. By stopped-flow light scattering, the liver glycerol permeability of ob/ob mice was significantly lower (53%) than lean mice, a finding consistent with both the observed down-regulation of AQP9 protein and increased level of plasma glycerol characterizing obese mice. In summary, our results suggest implication of AQP9 in liver steatosis. The reduction of hepatocyte AQP9 and, consequently, glycerol permeability might be a defensive mechanism to counteract further fat infiltration in liver parenchyma.
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Portincasa P, Calamita G. Water channel proteins in bile formation and flow in health and disease: when immiscible becomes miscible. Mol Aspects Med 2012; 33:651-64. [PMID: 22487565 DOI: 10.1016/j.mam.2012.03.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Revised: 03/29/2012] [Accepted: 03/31/2012] [Indexed: 12/19/2022]
Abstract
An essential function of the liver is the formation and secretion of bile, a complex aqueous solution of organic and inorganic compounds essential as route for the elimination of body cholesterol as unesterified cholesterol or as bile acids. In bile, a considerable amount of otherwise insoluble cholesterol is solubilized by carriers including two other classes of lipids, namely phospholipid and bile acids. Formation of bile and generation of bile flow are driven by the active secretion of bile acids, lipids and electrolytes into the canalicular and bile duct lumens followed by the parallel movement of water. Thus, water has to cross rapidly into and out of the cell interior driven by osmotic forces. Bile as a fluid, results from complicated interplay of hepatocyte and cholangiocyte uptake and secretion, concentration, by involving a number of transporters of lipids, anions, cations, and water. The discovery of the aquaporin water channels, has clarified the mechanisms by which water, the major component of bile (more than 95%), moves across the hepatobiliary epithelia. This review is focusing on novel acquisitions in liver membrane lipidic and water transport and functional participation of aquaporin water channels in multiple aspects of hepatobiliary fluid balance. Involvement of aquaporins in a series of clinically relevant hepatobiliary disorders are also discussed.
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Affiliation(s)
- Piero Portincasa
- University of Bari Medical School, Clinica Medica A. Murri, Department of Biomedical Sciences and Human Oncology, Policlinico Hospital, 70124 Bari, Italy.
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25
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Calamita G, Gena P, Ferri D, Rosito A, Rojek A, Nielsen S, Marinelli RA, Frühbeck G, Svelto M. Biophysical assessment of aquaporin-9 as principal facilitative pathway in mouse liver import of glucogenetic glycerol. Biol Cell 2012; 104:342-51. [PMID: 22316404 DOI: 10.1111/boc.201100061] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Accepted: 02/02/2012] [Indexed: 12/26/2022]
Abstract
BACKGROUND INFORMATION Lipolytic glycerol, released from adipocytes, flows through the bloodstream to the liver, where its utilisation in supplying hepatocyte gluconeogenesis is rate-limited by the permeation step. An aquaglyceroporin expressed in hepatocytes, aquaporin-9 (AQP9), has been often linked to liver uptake of glycerol. However, the truthfulness of this postulation and the potential existence of additional pathways of glycerol import by hepatocytes have never been assessed directly. Here, we define the identity and extent of liver glycerol transport and evaluate the correlation between hepatic AQP9 expression and glycerol permeability (P(gly) ) in AQP9(+/+) wild-type mice in different nutritional states and circulating insulin levels. The liver P(gly) of AQP9 null mice is also assessed. RESULTS By stopped-flow light scattering, facilitated diffusion of glycerol into hepatocytes was indicated by the low Arrhenius activation energy (3.5 kcal/mol) and strong inhibition by phloretin, an AQP9 blocker, that characterised the transport. Although fasting markedly increased hepatic AQP9, a straight parallelism was seen both in quantitative and time-space terms between P(gly) and AQP9 protein in AQP9(+/+) mice kept in fed or fasted/refed states. In line with these findings, the highest P(gly) (P(gly) ≈ 14.0 × 10(-6) cm/s at 20°C) at 18-h fasting coincided with the highest percent of phloretin inhibition (63%). Besides being markedly lower than that in AQP9(+/+) mice, the liver P(gly) of the AQP9 null mice did not increase during fasting. Reverse-transcription PCR analysis showed lack of compensation by AQP3 and AQP7, the other known murine glycerol facilitators, in AQP9 null mice. CONCLUSIONS Overall, these results experimentally prove major functional significance for AQP9 in maximising liver glycerol import during states requiring increased glucose production. If any, alternative facilitated pathways would be of minor importance in transporting glucogenetic glycerol into hepatocytes during starvation. Refining the understanding of liver AQP9 in metabolic and energy homeostasis may reveal helpful for therapeutic purposes.
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Affiliation(s)
- Giuseppe Calamita
- Dipartimento di Bioscienze, Biotecnologie e Scienze Farmacologiche, Università degli Studi di Bari Aldo Moro, Bari, Italy.
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