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Nakamura Y, Aizawa C, Kawata H, Nakanishi T. N-glycosylation modifies prostaglandin E 2 uptake by reducing cell surface expression of SLCO2A1. Prostaglandins Other Lipid Mediat 2023; 165:106714. [PMID: 36706979 DOI: 10.1016/j.prostaglandins.2023.106714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 01/10/2023] [Accepted: 01/23/2023] [Indexed: 01/26/2023]
Abstract
SLCO2A1 functions as a prostaglandin (PG) influx transporter to facilitate intracellular oxidation of PGs and its defect causes dysregulation of PG signaling and metabolism. This study aimed to clarify effects of N-glycosylation on functional SLCO2A1 expression. Putative N-glycosylation site(s) (N134, N478, and/or N491) of human SLCO2A1 were mutated to Q and wild-type (WT) and mutant forms were expressed in HEK293 and human epithelial cells. Molecular weight of WT decreased to nearly 55 kDa by PNGase F treatment and was identical to that of triple mutant (TM, i.e., N134Q/N478Q/N491Q). Transport affinity of TM for PGE2 (Km of 392.7 nM) was comparable to that of WT (Km of 328.5 nM); however, immunoassays showed that TM cell surface expression remained at 24% of WT in HEK293 cells, resulting in a reduced cellular PGE2 uptake. These results suggest N-glycosylation modifies cellular PGE2 uptake by decreasing SLCO2A1 localization to the plasma membrane.
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Affiliation(s)
- Yoshinobu Nakamura
- Laboratory of Membrane Transport for Biopharmaceutics, Faculty of Pharmacy, Takasaki University of Health and Welfare, Takasaki, Japan
| | - Chisato Aizawa
- Laboratory of Membrane Transport for Biopharmaceutics, Faculty of Pharmacy, Takasaki University of Health and Welfare, Takasaki, Japan
| | - Hinako Kawata
- Laboratory of Membrane Transport for Biopharmaceutics, Faculty of Pharmacy, Takasaki University of Health and Welfare, Takasaki, Japan
| | - Takeo Nakanishi
- Laboratory of Membrane Transport for Biopharmaceutics, Faculty of Pharmacy, Takasaki University of Health and Welfare, Takasaki, Japan.
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2
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Nakanishi T, Nakamura Y, Umeno J. Recent advances in studies of SLCO2A1 as a key regulator of the delivery of prostaglandins to their sites of action. Pharmacol Ther 2021; 223:107803. [PMID: 33465398 DOI: 10.1016/j.pharmthera.2021.107803] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 12/18/2020] [Indexed: 02/08/2023]
Abstract
Solute carrier organic anion transporter family member 2A1 (SLCO2A1, also known as PGT, OATP2A1, PHOAR2, or SLC21A2) is a plasma membrane transporter consisting of 12 transmembrane domains. It is ubiquitously expressed in tissues, and mediates the membrane transport of prostaglandins (PGs, mainly PGE2, PGF2α, PGD2) and thromboxanes (e.g., TxB2). SLCO2A1-mediated transport is electrogenic and is facilitated by an outwardly directed gradient of lactate. PGs imported by SLCO2A1 are rapidly oxidized by cytoplasmic 15-hydroxyprostaglandin dehydrogenase (15-PGDH, encoded by HPGD). Accumulated evidence suggests that SLCO2A1 plays critical roles in many physiological processes in mammals, and it is considered a potential pharmacological target for diabetic foot ulcer treatment, antipyresis, and non-hormonal contraception. Furthermore, whole-exome analyses suggest that recessive inheritance of SLCO2A1 mutations is associated with two refractory diseases, primary hypertrophic osteoarthropathy (PHO) and chronic enteropathy associated with SLCO2A1 (CEAS). Intriguingly, SLCO2A1 is also a key component of the Maxi-Cl channel, which regulates fluxes of inorganic and organic anions, including ATP. Further study of the bimodal function of SLCO2A1 as a transporter and ion channel is expected to throw new light on the complex pathology of human diseases. Here, we review and summarize recent information on the molecular functions of SLCO2A1, and we discuss its pathophysiological significance.
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Affiliation(s)
- Takeo Nakanishi
- Faculty of Pharmacy, Takasaki University of Health and Welfare, Takasaki, Gunma 370-0033, Japan.
| | - Yoshinobu Nakamura
- Faculty of Pharmacy, Takasaki University of Health and Welfare, Takasaki, Gunma 370-0033, Japan
| | - Junji Umeno
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Fukuoka 812-8582, Japan
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3
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Jiang Y, Du J, Song YW, Wang WB, Pang QQ, Li M, Wang O, Lian XL, Xing XP, Xia WB. Novel SLCO2A1compound heterozygous mutation causing primary hypertrophic osteoarthropathy with Bartter-like hypokalemia in a Chinese family. J Endocrinol Invest 2019; 42:1245-1252. [PMID: 31004291 DOI: 10.1007/s40618-019-01048-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2019] [Accepted: 04/08/2019] [Indexed: 11/29/2022]
Abstract
PURPOSE Primary hypertrophic osteoarthropathy (PHO) is an inherited disease characterized by digital clubbing, periostosis and pachydermia with defects in the degradation of prostaglandin E2 (PGE2). Mutations in SLCO2A1 gene-encoding prostaglandin transporter (PGT) resulted in PHO, autosomal recessive 2 (PHOAR2). The spectrum of mutations and variable clinical complications of PHOAR2 has been delineated. In this study, we investigated a Chinese PHO family with a manifestation of Bartter-like hypokalemia. METHODS Clinical manifestations were collected and genetic analyses were performed in the PHO family. RESULTS The 33-year-old male proband had severe hypokalemia due to potassium loss from the kidney, while his brother had mild hypokalemia. After being treated with etoricoxib, the serum potassium level of the patient increased rapidly to the normal range which corresponded with the reduction in his serum PGE2 and PE2 metabolite (PGEM) levels. A novel SLCO2A1 compound heterozygous mutation of p.I284V and p.C459R was identified in two PHO patients in this family. CONCLUSIONS The present findings supported that the Bartter-like hypokalemia is a new complication of PHOAR2 caused by the high level of PGE2. Etoricoxib was demonstrated to be effective for the renal hypokalemia in PHO patients.
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Affiliation(s)
- Y Jiang
- Department of Endocrinology, Key Laboratory of Endocrinology, National Health Commission, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, 100730, China
| | - J Du
- Department of Endocrinology, Key Laboratory of Endocrinology, National Health Commission, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, 100730, China
| | - Y-W Song
- Department of Endocrinology, Key Laboratory of Endocrinology, National Health Commission, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, 100730, China
| | - W-B Wang
- Department of Endocrinology, Key Laboratory of Endocrinology, National Health Commission, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, 100730, China
| | - Q-Q Pang
- Department of Endocrinology, Key Laboratory of Endocrinology, National Health Commission, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, 100730, China
| | - M Li
- Department of Endocrinology, Key Laboratory of Endocrinology, National Health Commission, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, 100730, China
| | - O Wang
- Department of Endocrinology, Key Laboratory of Endocrinology, National Health Commission, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, 100730, China
| | - X-L Lian
- Department of Endocrinology, Key Laboratory of Endocrinology, National Health Commission, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, 100730, China
| | - X-P Xing
- Department of Endocrinology, Key Laboratory of Endocrinology, National Health Commission, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, 100730, China
| | - W-B Xia
- Department of Endocrinology, Key Laboratory of Endocrinology, National Health Commission, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, 100730, China.
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4
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Nakanishi T, Tamai I. Roles of Organic Anion Transporting Polypeptide 2A1 (OATP2A1/SLCO2A1) in Regulating the Pathophysiological Actions of Prostaglandins. AAPS JOURNAL 2017; 20:13. [PMID: 29204966 DOI: 10.1208/s12248-017-0163-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 10/17/2017] [Indexed: 02/06/2023]
Abstract
Solute carrier organic anion transporter family member 2A1 (OATP2A1, encoded by the SLCO2A1 gene), which was initially identified as prostaglandin transporter (PGT), is expressed ubiquitously in tissues and mediates the distribution of prostanoids, such as PGE2, PGF2α, PGD2 and TxB2. It is well known to play a key role in the metabolic clearance of prostaglandins, which are taken up into the cell by OATP2A1 and then oxidatively inactivated by 15-ketoprostaglandin dehydrogenase (encoded by HPGD); indeed, OATP2A1-mediated uptake is the rate-limiting step of PGE2 catabolism. Consequently, since OATP2A1 activity is required for termination of prostaglandin signaling via prostanoid receptors, its inhibition can enhance such signaling. On the other hand, OATP2A1 can also function as an organic anion exchanger, mediating efflux of prostaglandins in exchange for import of anions such as lactate, and in this context, it plays a role in the release of newly synthesized prostaglandins from cells. These different functions likely operate in different compartments within the cell. OATP2A1 is reported to function at cytoplasmic vesicle/organelle membranes. As a regulator of the levels of physiologically active prostaglandins, OATP2A1 is implicated in diverse physiological and pathophysiological processes in many organs. Recently, whole exome analysis has revealed that recessive mutations in SLCO2A1 cause refractory diseases in humans, including primary hypertrophic osteoarthropathy (PHO) and chronic non-specific ulcers in small intestine (CNSU). Here, we review and summarize recent information on the molecular functions of OATP2A1 and on its physiological and pathological significance.
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Affiliation(s)
- Takeo Nakanishi
- Department of Membrane Transport and Biopharmaceutics, Faculty of Pharmaceutical Sciences, Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan.
| | - Ikumi Tamai
- Department of Membrane Transport and Biopharmaceutics, Faculty of Pharmaceutical Sciences, Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan
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5
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Ware JS, Wain LV, Channavajjhala SK, Jackson VE, Edwards E, Lu R, Siew K, Jia W, Shrine N, Kinnear S, Jalland M, Henry AP, Clayton J, O'Shaughnessy KM, Tobin MD, Schuster VL, Cook S, Hall IP, Glover M. Phenotypic and pharmacogenetic evaluation of patients with thiazide-induced hyponatremia. J Clin Invest 2017; 127:3367-3374. [PMID: 28783044 PMCID: PMC5669583 DOI: 10.1172/jci89812] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 06/15/2017] [Indexed: 12/17/2022] Open
Abstract
Thiazide diuretics are among the most widely used treatments for hypertension, but thiazide-induced hyponatremia (TIH), a clinically significant adverse effect, is poorly understood. Here, we have studied the phenotypic and genetic characteristics of patients hospitalized with TIH. In a cohort of 109 TIH patients, those with severe TIH displayed an extended phenotype of intravascular volume expansion, increased free water reabsorption, urinary prostaglandin E2 excretion, and reduced excretion of serum chloride, magnesium, zinc, and antidiuretic hormone. GWAS in a separate cohort of 48 TIH patients and 2,922 controls from the 1958 British birth cohort identified an additional 14 regions associated with TIH. We identified a suggestive association with a variant in SLCO2A1, which encodes a prostaglandin transporter in the distal nephron. Resequencing of SLCO2A1 revealed a nonsynonymous variant, rs34550074 (p.A396T), and association with this SNP was replicated in a second cohort of TIH cases. TIH patients with the p.A396T variant demonstrated increased urinary excretion of prostaglandin E2 and metabolites. Moreover, the SLCO2A1 phospho-mimic p.A396E showed loss of transporter function in vitro. These findings indicate that the phenotype of TIH involves a more extensive metabolic derangement than previously recognized. We propose one mechanism underlying TIH development in a subgroup of patients in which SLCO2A1 regulation is altered.
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Affiliation(s)
- James S Ware
- NIHR Biomedical Research Unit in Cardiovascular Disease at Royal Brompton & Harefield, NHS Foundation Trust and Imperial College London, London, United Kingdom.,National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Louise V Wain
- Genetic Epidemiology Group, Department of Health Sciences, University of Leicester, Leicester, United Kingdom
| | - Sarath K Channavajjhala
- Division of Therapeutics and Molecular Medicine, University of Nottingham, Nottingham, United Kingdom.,NIHR Nottingham Biomedical Research Centre, Nottingham, United Kingdom
| | - Victoria E Jackson
- Genetic Epidemiology Group, Department of Health Sciences, University of Leicester, Leicester, United Kingdom
| | - Elizabeth Edwards
- NIHR Biomedical Research Unit in Cardiovascular Disease at Royal Brompton & Harefield, NHS Foundation Trust and Imperial College London, London, United Kingdom.,National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Run Lu
- Albert Einstein College of Medicine, Yeshiva University, New York, New York, USA
| | - Keith Siew
- Clinical Pharmacology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Wenjing Jia
- Division of Therapeutics and Molecular Medicine, University of Nottingham, Nottingham, United Kingdom.,NIHR Nottingham Biomedical Research Centre, Nottingham, United Kingdom
| | - Nick Shrine
- Genetic Epidemiology Group, Department of Health Sciences, University of Leicester, Leicester, United Kingdom
| | - Sue Kinnear
- Division of Therapeutics and Molecular Medicine, University of Nottingham, Nottingham, United Kingdom.,NIHR Nottingham Biomedical Research Centre, Nottingham, United Kingdom
| | - Mahli Jalland
- Division of Therapeutics and Molecular Medicine, University of Nottingham, Nottingham, United Kingdom.,NIHR Nottingham Biomedical Research Centre, Nottingham, United Kingdom
| | - Amanda P Henry
- Division of Therapeutics and Molecular Medicine, University of Nottingham, Nottingham, United Kingdom.,NIHR Nottingham Biomedical Research Centre, Nottingham, United Kingdom
| | - Jenny Clayton
- Department of Diabetes and Endocrinology, Nottingham University Hospitals NHS Trust, Nottingham, United Kingdom
| | | | - Martin D Tobin
- Genetic Epidemiology Group, Department of Health Sciences, University of Leicester, Leicester, United Kingdom
| | - Victor L Schuster
- Albert Einstein College of Medicine, Yeshiva University, New York, New York, USA
| | - Stuart Cook
- National Heart and Lung Institute, Imperial College London, London, United Kingdom.,Duke-National University of Singapore, Singapore.,National Heart Centre Singapore, Singapore
| | - Ian P Hall
- Division of Therapeutics and Molecular Medicine, University of Nottingham, Nottingham, United Kingdom.,NIHR Nottingham Biomedical Research Centre, Nottingham, United Kingdom
| | - Mark Glover
- Division of Therapeutics and Molecular Medicine, University of Nottingham, Nottingham, United Kingdom.,NIHR Nottingham Biomedical Research Centre, Nottingham, United Kingdom
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6
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Madonna R, Balistreri CR, Geng YJ, De Caterina R. Diabetic microangiopathy: Pathogenetic insights and novel therapeutic approaches. Vascul Pharmacol 2017; 90:1-7. [PMID: 28137665 DOI: 10.1016/j.vph.2017.01.004] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 01/26/2017] [Indexed: 12/11/2022]
Abstract
Diabetic microangiopathy, including retinopathy, is characterized by abnormal growth and leakage of small blood vessels, resulting in local edema and functional impairment of the depending tissues. Mechanisms leading to the impairment of microcirculation in diabetes are multiple and still largely unclear. However, a dysregulated vascular regeneration appears to play a key role. In addition, oxidative and hyperosmolar stress, as well as the activation of inflammatory pathways triggered by advanced glycation end-products and toll-like receptors, have been recognized as key underlying events. Here, we review recent knowledge on cellular and molecular pathways of microvascular disease in diabetes. We also highlight how new insights into pathogenic mechanisms of vascular damage in diabetes may indicate new targets for prevention and treatment.
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Affiliation(s)
- Rosalinda Madonna
- Center of Excellence on Aging (CesiMet), Institute of Cardiology, Department of Neurosciences, Imaging and Clinical Sciences, "G. d'Annunzio" University, Chieti, Italy; The Texas Heart Institute, Center for Cardiovascular Biology and Atherosclerosis Research, Department of Internal Medicine, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Carmela Rita Balistreri
- Department of Pathobiology and Medical Biotechnologies, University of Palermo, Palermo, Italy
| | - Yong-Jian Geng
- The Texas Heart Institute, Center for Cardiovascular Biology and Atherosclerosis Research, Department of Internal Medicine, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Raffaele De Caterina
- Center of Excellence on Aging (CesiMet), Institute of Cardiology, Department of Neurosciences, Imaging and Clinical Sciences, "G. d'Annunzio" University, Chieti, Italy.
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7
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Kasai T, Nakanishi T, Ohno Y, Shimada H, Nakamura Y, Arakawa H, Tamai I. Role of OATP2A1 in PGE(2) secretion from human colorectal cancer cells via exocytosis in response to oxidative stress. Exp Cell Res 2016; 341:123-31. [PMID: 26850138 DOI: 10.1016/j.yexcr.2016.02.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 01/29/2016] [Accepted: 02/01/2016] [Indexed: 12/30/2022]
Abstract
Chronic inflammation induced by reactive oxygen species is associated with increased risk of developing colorectal cancer (CRC), and prostaglandin E2 (PGE2), which serves as a key mediator of inflammatory responses, plays an important role in CRC initiation and progression. Therefore, in the present study, we aimed to investigate the role of prostaglandin transporter OATP2A1/SLCO2A1 in the changes of PGE2 disposition in CRC cells in response to oxidative stress. H2O2 induced translocation of cytoplasmic OATP2A1 to plasma membranes in LoVo and COLO 320DM cells, but not in Caco-2 cells. The shift of subcellular OATP2A1 was abolished in the presence of anti-oxidant N-acetyl-L-cysteine or an inhibitor of protein kinase C, which evokes exocytosis. Exposure of LoVo cells to H2O2 caused an increase in the amount of extracellular PGE2 without changing the sum of intra- and extracellular PGE2. OATP2A1 knockdown decreased extracellular PGE2 in LoVo cells. In addition, extracellular PGE2 was significantly reduced by exocytosis inhibitor cytochalasin D, suggesting that H2O2-induced PGE2 release occurs in an exocytotic manner. Furthermore, mRNA expression of vascular endothelial growth factor (VEGF) was significantly reduced in LoVo cells by knockdown of OATP2A1. These results suggest that cytoplasmic OATP2A1 likely facilitates PGE2 loading into suitable intracellular compartment(s) for efficient exocytotic PGE2 release from CRC cells exposed to oxidative stress.
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Affiliation(s)
- Taku Kasai
- Faculty of Pharmaceutical Science, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Takeo Nakanishi
- Faculty of Pharmaceutical Science, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Yasuhiro Ohno
- Faculty of Pharmaceutical Science, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Hiroaki Shimada
- Faculty of Pharmaceutical Science, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Yoshinobu Nakamura
- Faculty of Pharmaceutical Science, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Hiroshi Arakawa
- Faculty of Pharmaceutical Science, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Ikumi Tamai
- Faculty of Pharmaceutical Science, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
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8
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Madonna R, Giovannelli G, Confalone P, Renna FV, Geng YJ, De Caterina R. High glucose-induced hyperosmolarity contributes to COX-2 expression and angiogenesis: implications for diabetic retinopathy. Cardiovasc Diabetol 2016; 15:18. [PMID: 26822858 PMCID: PMC4731895 DOI: 10.1186/s12933-016-0342-4] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 01/22/2016] [Indexed: 12/26/2022] Open
Abstract
Background We tested the hypothesis that glucose-induced hyperosmolarity, occurring in diabetic hyperglycemia, promotes retinal angiogenesis, and that interference with osmolarity signaling ameliorates excessive angiogenesis and retinopathy in vitro and in vivo. Methods and Results We incubated human aortic (HAECs) and dermal microvascular endothelial cells (HMVECs) with glucose or mannitol for 24 h and tested them for protein levels and in vitro angiogenesis. We used the Ins2 Akita mice as a model of type 1 diabetes to test the in vivo relevance of in vitro observations. Compared to incubations with normal (5 mmol/L) glucose concentrations, cells exposed to both high glucose and high mannitol (at 30.5 or 50.5 mmol/L) increased expression of the water channel aquaporin-1 (AQP1) and cyclooxygenase (COX)-2. This was preceded by increased activity of the osmolarity-sensitive transcription factor Tonicity enhancer binding protein (TonEBP), and enhanced endothelial migration and tubulization in Matrigel, reverted by treatment with AQP1 and TonEBP siRNA. Retinas of Ins2 Akita mice showed increased levels of AQP1 and COX-2, as well as angiogenesis, all reverted by AQP1 siRNA intravitreal injections. Conclusions Glucose-related hyperosmolarity seems to be able to promote angiogenesis and retinopathy through activation of TonEBP and possibly increasing expression of AQP1 and COX-2. Osmolarity signaling may be a target for therapy.
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Affiliation(s)
- Rosalinda Madonna
- Laboratory of Experimental Cardiology, Center of Excellence on Aging, Institute of Cardiology, "G. d'Annunzio" University, C/o Ospedale SS. Annunziata, Via dei Vestini, 31, 66013, Chieti, Italy. .,The University of Texas Health Science Center at Houston and the Texas Heart Institute, Houston, TX, USA.
| | - Gaia Giovannelli
- Department of Neurosciences and Imaging, "G. d'Annunzio" University, Chieti, Italy.
| | - Pamela Confalone
- Laboratory of Experimental Cardiology, Center of Excellence on Aging, Institute of Cardiology, "G. d'Annunzio" University, C/o Ospedale SS. Annunziata, Via dei Vestini, 31, 66013, Chieti, Italy.
| | - Francesca Vera Renna
- Laboratory of Experimental Cardiology, Center of Excellence on Aging, Institute of Cardiology, "G. d'Annunzio" University, C/o Ospedale SS. Annunziata, Via dei Vestini, 31, 66013, Chieti, Italy.
| | - Yong-Jian Geng
- The University of Texas Health Science Center at Houston and the Texas Heart Institute, Houston, TX, USA.
| | - Raffaele De Caterina
- Laboratory of Experimental Cardiology, Center of Excellence on Aging, Institute of Cardiology, "G. d'Annunzio" University, C/o Ospedale SS. Annunziata, Via dei Vestini, 31, 66013, Chieti, Italy.
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9
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Shimada H, Nakamura Y, Nakanishi T, Tamai I. OATP2A1/SLCO2A1-mediated prostaglandin E2 loading into intracellular acidic compartments of macrophages contributes to exocytotic secretion. Biochem Pharmacol 2015; 98:629-38. [PMID: 26474801 DOI: 10.1016/j.bcp.2015.10.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 10/09/2015] [Indexed: 12/19/2022]
Abstract
There is significant evidence that the inducible cyclooxygenase isoform (COX-2) regulates the pericellular concentration of PGE2; however, the mechanism of the secretory process remains unclear. The present study, therefore, aimed to evaluate the role of prostaglandin transporter (OATP2A1) in PGE2 secretion from macrophages. Immunofluorescence staining for Oatp2a1 (Slco2a1) was primarily detected in cytoplasmic domains, and was partially co-localized with anti-PGE2 antibody, LysoTracker®, and anti-lysosome-associated membrane protein (Lamp) 1 antibody in murine macrophage-derived RAW264 cells and peritoneal macrophages (PMs). PGE2 uptake by subcellular fraction containing light lysosomes was reduced significantly in the presence of an OATP inhibitor and in Slco2a1(+/-) PMs. Secretion of PGE2 and lysosome-specific N-acetyl-β-d-glucosaminidase was enhanced in activated macrophagic cells, and diminished significantly under the Ca(2+)-depleted condition. The amount of PGE2 secreted from lipopolysaccharide-activated Slco2a1(-/-) PMs was significantly lower than that from PMs from wild type (WT) mice. Expression of Cox-2 and 15-hydroxyprostaglandin dehydrogenase (15-Pgdh) was unchanged between PMs from Slco2a1(-/-) and WT mice. These results suggest that OATP2A1 is involved in PGE2-loading into intracellular acidic compartments, including light lysosomes. Thus, OATP2A1 contributes to PGE2 secretion by macrophages via exocytosis induced by Ca(2+) influx, independently of PGE2 synthesis and metabolism.
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Affiliation(s)
- Hiroaki Shimada
- Department of Membrane Transport and Biopharmaceutics, Faculty of Pharmaceutical Science, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Yoshinobu Nakamura
- Department of Membrane Transport and Biopharmaceutics, Faculty of Pharmaceutical Science, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Takeo Nakanishi
- Department of Membrane Transport and Biopharmaceutics, Faculty of Pharmaceutical Science, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
| | - Ikumi Tamai
- Department of Membrane Transport and Biopharmaceutics, Faculty of Pharmaceutical Science, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
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10
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Rajagopal M, Thomas SV, Kathpalia PP, Chen Y, Pao AC. Prostaglandin E2 induces chloride secretion through crosstalk between cAMP and calcium signaling in mouse inner medullary collecting duct cells. Am J Physiol Cell Physiol 2013; 306:C263-78. [PMID: 24284792 DOI: 10.1152/ajpcell.00381.2012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Under conditions of high dietary salt intake, prostaglandin E2 (PGE2) production is increased in the collecting duct and promotes urinary sodium chloride (NaCl) excretion; however, the molecular mechanisms by which PGE2 increases NaCl excretion in this context have not been clearly defined. We used the mouse inner medullary collecting duct (mIMCD)-K2 cell line to characterize mechanisms underlying PGE2-regulated NaCl transport. When epithelial Na(+) channels were inhibited, PGE2 exclusively stimulated basolateral EP4 receptors to increase short-circuit current (Isc(PGE2)). We found that Isc(PGE2) was sensitive to inhibition by H-89 and CFTR-172, indicating that EP4 receptors signal through protein kinase A to induce Cl(-) secretion via cystic fibrosis transmembrane conductance regulator (CFTR). Unexpectedly, we also found that Isc(PGE2) was sensitive to inhibition by BAPTA-AM (Ca(2+) chelator), 2-aminoethoxydiphenyl borate (2-APB) (inositol triphosphate receptor blocker), and flufenamic acid (FFA) [Ca(2+)-activated Cl(-) channel (CACC) inhibitor], suggesting that EP4 receptors also signal through Ca(2+) to induce Cl(-) secretion via CACC. Additionally, we observed that PGE2 stimulated an increase in Isc through crosstalk between cAMP and Ca(2+) signaling; BAPTA-AM or 2-APB inhibited a component of Isc(PGE2) that was sensitive to CFTR-172 inhibition; H-89 inhibited a component of Isc(PGE2) that was sensitive to FFA inhibition. Together, our findings indicate that PGE2 activates basolateral EP4 receptors and signals through both cAMP and Ca(2+) to stimulate Cl(-) secretion in IMCD-K2 cells. We propose that these signaling pathways, and the crosstalk between them, may provide a concerted mechanism for enhancing urinary NaCl excretion under conditions of high dietary NaCl intake.
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Affiliation(s)
- Madhumitha Rajagopal
- Division of Nephrology, Department of Medicine, Stanford University, Palo Alto, California; and
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11
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Fujii Y, Okada A, Yasui T, Niimi K, Hamamoto S, Hirose M, Kubota Y, Tozawa K, Hayashi Y, Kohri K. Effect of adiponectin on kidney crystal formation in metabolic syndrome model mice via inhibition of inflammation and apoptosis. PLoS One 2013; 8:e61343. [PMID: 23630583 PMCID: PMC3632593 DOI: 10.1371/journal.pone.0061343] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2012] [Accepted: 03/07/2013] [Indexed: 12/03/2022] Open
Abstract
The aims of the present study were to elucidate a possible mechanism of kidney crystal formation by using a metabolic syndrome (MetS) mouse model and to assess the effectiveness of adiponectin treatment for the prevention of kidney crystals. Further, we performed genome-wide expression analyses for investigating novel genetic environmental changes. Wild-type (+/+) mice showed no kidney crystal formation, whereas ob/ob mice showed crystal depositions in their renal tubules. However, this deposition was remarkably reduced by adiponectin. Expression analysis of genes associated with MetS-related kidney crystal formation identified 259 genes that were >2.0-fold up-regulated and 243 genes that were <0.5-fold down-regulated. Gene Ontology (GO) analyses revealed that the up-regulated genes belonged to the categories of immunoreaction, inflammation, and adhesion molecules and that the down-regulated genes belonged to the categories of oxidative stress and lipid metabolism. Expression analysis of adiponectin-induced genes related to crystal prevention revealed that the numbers of up- and down-regulated genes were 154 and 190, respectively. GO analyses indicated that the up-regulated genes belonged to the categories of cellular and mitochondrial repair, whereas the down-regulated genes belonged to the categories of immune and inflammatory reactions and apoptosis. The results of this study provide compelling evidence that the mechanism of kidney crystal formation in the MetS environment involves the progression of an inflammation and immunoresponse, including oxidative stress and adhesion reactions in renal tissues. This is the first report to prove the preventive effect of adiponectin treatment for kidney crystal formation by renoprotective activities and inhibition of inflammation and apoptosis.
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Affiliation(s)
- Yasuhiro Fujii
- Department of Nephro-urology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Atsushi Okada
- Department of Nephro-urology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Takahiro Yasui
- Department of Nephro-urology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Kazuhiro Niimi
- Department of Nephro-urology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Shuzo Hamamoto
- Department of Nephro-urology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Masahito Hirose
- Department of Nephro-urology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Yasue Kubota
- Department of Nephro-urology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Keiichi Tozawa
- Department of Nephro-urology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Yutaro Hayashi
- Department of Nephro-urology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Kenjiro Kohri
- Department of Nephro-urology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
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12
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Shiraya K, Hirata T, Hatano R, Nagamori S, Wiriyasermkul P, Jutabha P, Matsubara M, Muto S, Tanaka H, Asano S, Anzai N, Endou H, Yamada A, Sakurai H, Kanai Y. A novel transporter of SLC22 family specifically transports prostaglandins and co-localizes with 15-hydroxyprostaglandin dehydrogenase in renal proximal tubules. J Biol Chem 2010; 285:22141-51. [PMID: 20448048 DOI: 10.1074/jbc.m109.084426] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
We identified a novel prostaglandin (PG)-specific organic anion transporter (OAT) in the OAT group of the SLC22 family. The transporter designated OAT-PG from mouse kidney exhibited Na(+)-independent and saturable transport of PGE(2) when expressed in a proximal tubule cell line (S(2)). Unusual for OAT members, OAT-PG showed narrow substrate selectivity and high affinity for a specific subset of PGs, including PGE(2), PGF(2alpha), and PGD(2). Similar to PGE(2) receptor and PGT, a structurally distinct PG transporter, OAT-PG requires for its substrates an alpha-carboxyl group, with a double bond between C13 and C14 as well as a (S)-hydroxyl group at C15. Unlike the PGE(2) receptor, however, the hydroxyl group at C11 in a cyclopentane ring is not essential for OAT-PG substrates. Addition of a hydroxyl group at C19 or C20 impairs the interaction with OAT-PG, whereas an ethyl group at C20 enhances the interaction, suggesting the importance of hydrophobicity around the omega-tail tip forming a "hydrophobic core" accompanied by a negative charge, which is essential for substrates of OAT members. OAT-PG-mediated transport is concentrative in nature, although OAT-PG mediates both facilitative and exchange transport. OAT-PG is kidney-specific and localized on the basolateral membrane of proximal tubules where a PG-inactivating enzyme, 15-hydroxyprostaglandin dehydrogenase, is expressed. Because of the fact that 15-keto-PGE(2), the metabolite of PGE(2) produced by 15-hydroxyprostaglandin dehydrogenase, is not a substrate of OAT-PG, the transport-metabolism coupling would make unidirectional PGE(2) transport more efficient. By removing extracellular PGE(2), OAT-PG is proposed to be involved in the local PGE(2) clearance and metabolism for the inactivation of PG signals in the kidney cortex.
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Affiliation(s)
- Katsuko Shiraya
- Department of Pharmacology and Toxicology, Kyorin University School of Medicine, Mitaka, Tokyo 181-8611, Japan
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13
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Chang HY, Locker J, Lu R, Schuster VL. Failure of postnatal ductus arteriosus closure in prostaglandin transporter-deficient mice. Circulation 2010; 121:529-36. [PMID: 20083684 DOI: 10.1161/circulationaha.109.862946] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Prostaglandin E(2) (PGE(2)) plays a major role both in maintaining patency of the fetal ductus arteriosus and in closure of the ductus arteriosus after birth. The rate-limiting step in PGE(2) signal termination is PGE(2) uptake by the transporter PGT. METHODS AND RESULTS To determine the role of PGT in ductus arteriosus closure, we used a gene-targeting strategy to produce mice in which PGT exon 1 was flanked by loxP sites. Successful targeting was obtained because neither mice hypomorphic at the PGT allele (PGT Neo/Neo) nor global PGT knockout mice (PGT(-/-)) exhibited PGT protein expression; moreover, embryonic fibroblasts isolated from targeted mice failed to exhibit carrier-mediated PGE(2) uptake. Although born in a normal mendelian ratio, no PGT(-/-) mice survived past postnatal day 1, and no PGT Neo/Neo mice survived past postnatal day 2. Necropsy revealed patent ductus arteriosus with normal intimal thickening but dilated cardiac chambers. Both PGT Neo/Neo and PGT(-/-) mice could be rescued through the postnatal period by giving the mother indomethacin before birth. Rescued mice grew normally and had no abnormalities by gross and microscopic postmortem analyses. In accordance with the known role of PGT in metabolizing PGE(2), rescued adult PGT(-/-) mice had lower plasma PGE(2) metabolite levels and higher urinary PGE(2) excretion rates than wild-type mice. CONCLUSIONS PGT plays a critical role in closure of the ductus arteriosus after birth by ensuring a reduction in local and/or circulating PGE(2) concentrations.
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Affiliation(s)
- Hee-Yoon Chang
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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14
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Brain metabolism dictates the polarity of astrocyte control over arterioles. Nature 2008; 456:745-9. [PMID: 18971930 DOI: 10.1038/nature07525] [Citation(s) in RCA: 541] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Accepted: 10/10/2008] [Indexed: 12/12/2022]
Abstract
Calcium signalling in astrocytes couples changes in neural activity to alterations in cerebral blood flow by eliciting vasoconstriction or vasodilation of arterioles. However, the mechanism for how these opposite astrocyte influences provide appropriate changes in vessel tone within an environment that has dynamic metabolic requirements remains unclear. Here we show that the ability of astrocytes to induce vasodilations over vasoconstrictions relies on the metabolic state of the rat brain tissue. When oxygen availability is lowered and astrocyte calcium concentration is elevated, astrocyte glycolysis and lactate release are maximized. External lactate attenuates transporter-mediated uptake from the extracellular space of prostaglandin E(2), leading to accumulation and subsequent vasodilation. In conditions of low oxygen concentration extracellular adenosine also increases, which blocks astrocyte-mediated constriction, facilitating dilation. These data reveal the role of metabolic substrates in regulating brain blood flow and provide a mechanism for differential astrocyte control over cerebrovascular diameter during different states of brain activation.
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15
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Gatalica Z, Lilleberg SL, Koul MS, Vanecek T, Hes O, Wang B, Michal M. COX-2 gene polymorphisms and protein expression in renomedullary interstitial cell tumors. Hum Pathol 2008; 39:1495-504. [DOI: 10.1016/j.humpath.2008.02.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2008] [Revised: 02/25/2008] [Accepted: 02/27/2008] [Indexed: 01/22/2023]
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16
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Chi Y, Pucci ML, Schuster VL. Dietary salt induces transcription of the prostaglandin transporter gene in renal collecting ducts. Am J Physiol Renal Physiol 2008; 295:F765-71. [PMID: 18579702 DOI: 10.1152/ajprenal.00564.2007] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Prostaglandin E(2) (PGE(2)) plays an important role in maintaining body fluid homeostasis by activating its receptors on the renal collecting duct (CD) to stimulate renal Na(+) and water excretion. The PG carrier prostaglandin transporter (PGT) is expressed on the CD apical membrane, where it mediates PG reuptake as part of the termination of autocrine PG signaling. Here we tested the hypothesis that dietary salt loading regulates PGT gene transcription in renal CDs. We placed green fluorescence protein (GFP) under control of 3.3 kb of the mouse PGT promoter and injected this construct into the pronuclei of fertilized FVB mouse eggs. Four of thirty-eight offspring were GFP positive by genotyping. We extensively characterized one (no. 29) PGT-GFP transgenic mouse line. On microscopic examination, GFP was expressed in CDs as determined by their expression of aquaporin-2. We fed mice a low (0.03% NaCl)-, normal (0.3% NaCl)-, or high-salt (3% NaCl) diet for 2 wk and quantified CD GFP expression. The average number of GFP-positive CD cells per microscopic section varied directly with dietary salt intake. Compared with mice on the control (0.3% sodium) diet, mice on a low-sodium (0.03%) diet had reduced numbers of GFP-positive cells (71% of control, P < 0.001), whereas mice on a high-sodium (3%) diet had increased numbers of GFP-positive cells (139% of control, P < 0.001). This increase in apparent CD PGT transcription resulted in a 51-55% increase (P < 0.001) in whole kidney PGT mRNA levels as determined by real-time PCR. The regulation of PG signal termination via reuptake represents a new pathway for controlling renal Na(+) balance.
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Affiliation(s)
- Yuling Chi
- Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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17
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Abstract
Cyclooxygenase-derived prostanoids exert complex and diverse functions within the kidney. The biological effect of each prostanoid is controlled at multiple levels, including (a) enzymatic reactions catalyzed sequentially by cyclooxygenase and prostanoid synthase for the synthesis of bioactive prostanoid and (b) the interaction with its receptors that mediate its functions. Cyclooxygenase-derived prostanoids act in an autocrine or a paracrine fashion and can serve as physiological buffers, protecting the kidney from excessive functional changes during physiological stress. Through these actions, prostanoids play important roles in maintaining renal function, body fluid homeostasis, and blood pressure. Renal cortical COX2-derived prostanoids, particularly PGI2 and PGE2, play critical roles in maintaining blood pressure and renal function in volume-contracted states. Renal medullary COX2-derived prostanoids appear to have an antihypertensive effect in individuals challenged with a high-salt diet. Loss of EP2 or IP receptor is associated with salt-sensitive hypertension. COX2 also plays a role in maintaining renal medullary interstitial cell viability in the hypertonic environment of the medulla. Cyclooxygenase-derived prostanoids also are involved in certain pathological processes. The cortical COX2-derived PGI2 participates in the pathogenesis of renal vascular hypertension through stimulating renal renin synthesis and release. COX-derived prostanoids also appear to be involved in the pathogenesis of diabetic nephropathy. COXs, prostanoid synthases, and prostanoid receptors should provide fruitful targets for intervention in the pharmacological treatment of renal disease.
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Affiliation(s)
- Chuan-Ming Hao
- Division of Nephrology, Department of Medicine, Vanderbilt University, and Veterans Affair Medical Center, Nashville, TN 37232, USA.
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18
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Khandrika L, Kim FJ, Campagna A, Koul S, Meacham RB, Koul HK. Primary culture and characterization of human renal inner medullary collecting duct epithelial cells. J Urol 2008; 179:2057-63. [PMID: 18355855 DOI: 10.1016/j.juro.2008.01.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2007] [Indexed: 11/15/2022]
Abstract
PURPOSE Our understanding of physiological and pathophysiological events associated with inner medullary collecting duct epithelium is based on studies in cells isolated from mice and rats. We established primary cultures of hIMCD (human papillary collecting duct epithelial) cells. MATERIALS AND METHODS Normal papillary tissues were dissected from the surgical waste of consenting patients undergoing renal surgery. Tissues were digested enzymatically. Cells were maintained in Dulbecco's modified Eagle's medium supplemented with glucose and antibiotics. Cultures were treated with ethylenediaminetetraacetic acid and epithelial select medium was also used to obtain a pure epithelial culture. RESULTS The hIMCD cells grew in a monolayer. Cells showed the expression of epithelial specific markers, including cytokeratin, the tight junction marker zonula occludens 1 and the cytoskeletal protein vimentin. They lacked expression of factor VIII, which is a glycoprotein synthesized by endothelial cells. To our knowledge we also noted for the first time uroplakin expression in collecting duct epithelial cells. This expression was maintained in primary culture. The hIMCD cells in culture were highly resistant to hypertonic solutions and they responded to hypertonicity by cyclooxygenase-2 over expression. Moreover, these cells also survived prolonged periods of hypoxia. CONCLUSIONS To our knowledge this is the first report of successful culture and characterization of primary cultures of collecting duct epithelial cells from human renal papillae. These cells will serve as essential tools in helping us fill the gaps in our understanding of the events associated with the physiology and pathophysiology of human renal inner medullary collecting duct epithelium.
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Affiliation(s)
- Lakshmipathi Khandrika
- Signal Transduction and Molecular Urology Laboratory, Division of Urology, Department of Surgery, School of Medicine, University of Colorado at Denver and Health Sciences Center, Denver, Colorado 80262, USA
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19
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Gomez-Sanchez EP, Romero DG, de Rodriguez AF, Warden MP, Krozowski Z, Gomez-Sanchez CE. Hexose-6-phosphate dehydrogenase and 11beta-hydroxysteroid dehydrogenase-1 tissue distribution in the rat. Endocrinology 2008; 149:525-33. [PMID: 18039793 PMCID: PMC2219311 DOI: 10.1210/en.2007-0328] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Intracellular concentrations of the glucocorticoids cortisol and corticosterone are modulated by the enzymes 11beta-hydroxysteroid dehydrogenase (11beta-HSD) 1 and 2. 11beta-HSD1 is a reduced nicotinamide adenine dinucleotide phosphate (NADPH)-dependent microsomal reductase that converts the inactive glucocorticoids cortisone and 11-dehydrocorticosterone to their active forms, cortisol and corticosterone. Hexose-6-phosphate dehydrogenase (H6PDH) is an enzyme that generates NADPH from oxidized NADP (NADP(+)) within the endoplasmic reticulum. In the absence of NADPH or H6PDH to regenerate NADPH, 11beta-HSD1 acts as a dehydrogenase and inactivates glucocorticoids, as does 11beta-HSD2. A monoclonal antibody against H6PDH was produced to study the possibility that 11beta-HSD1 in the absence of H6PDH may be responsible for hydroxysteroid dehydrogenase activity in tissues that do not express significant amounts of 11beta-HSD2. H6PDH and 11beta-HSD1 expression was surveyed in a variety of rat tissues by real-time RT-PCR, Western blot analysis, and immunohistochemistry. H6PDH was found in a wide variety of tissues, with the greatest concentrations in the liver, kidney, and Leydig cells. Although the brain as a whole did not express significant amounts of H6PDH, some neurons were clearly immunoreactive by immunohistochemistry. H6PDH was amply expressed in most tissues examined in which 11beta-HSD1 was also expressed, with the notable exception of the renal interstitial cells, in which dehydrogenase activity by 11beta-HSD1 probably moderates activation of the glucocorticoid receptor because rat renal interstitial cells do not have significant amounts of mineralocorticoid receptors. This antibody against the H6PDH should prove useful for further studies of enzyme activity requiring NADPH generation within the endoplasmic reticulum.
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Affiliation(s)
- Elise P Gomez-Sanchez
- Research Service, GV (Sonny) Montgomery Veterans Affairs Medical Center, Jackson, MS 39216, USA.
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