151
|
Abstract
The approval of febuxostat, a non-purine-analogue inhibitor of xanthine oxidase, by the European Medicines Agency and the US Food and Drug Administration heralds a new era in the treatment of gout. The use of modified uricases to rapidly reduce serum urate concentrations in patients with otherwise untreatable gout is progressing. Additionally, advances in our understanding of the transport of uric acid in the renal proximal tubule and the inflammatory response to monosodium urate crystals are translating into potential new treatments. In this Review, we focus on the clinical trials of febuxostat. We also review results from studies of pegloticase, a pegylated uricase in development, and we summarise data for several other pipeline drugs for gout, such as the selective uricosuric drug RDEA594 and various interleukin-1 inhibitors. Finally, we issue a word of caution about the proper use of the new drugs and the already available drugs for gout. At a time of important advances, we need to recommit ourselves to a rational approach to the treatment of gout.
Collapse
|
152
|
Ng DY, Stocker SL, Graham GG, Williams KM, Day RO. Lack of effect of hydrochlorothiazide and low-dose aspirin on the renal clearance of urate and oxypurinol after a single dose of allopurinol in normal volunteers. Eur J Clin Pharmacol 2010; 67:709-13. [PMID: 21181139 DOI: 10.1007/s00228-010-0963-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Accepted: 11/23/2010] [Indexed: 11/30/2022]
Abstract
AIMS To determine whether low-dose aspirin and hydrochlorothiazide (HCTZ) affect the renal clearance of oxypurinol and/or urate. METHODS Healthy volunteers (n = 8) were treated with allopurinol (600 mg, control), and allopurinol (600 mg) co-administered with single doses of aspirin (100 mg) or HCTZ (25 mg) or a combination of the two. RESULTS Hydrochlorothiazide, low-dose aspirin or a combination of the two, when co-administered with allopurinol, did not significantly alter (P > 0.05) the renal clearance of oxypurinol or urate. In particular, aspirin and HCTZ, when taken together and with allopurinol, did not change (P > 0.05) oxypurinol fractional renal clearance (allopurinol alone: 0.217, 0.173-0.262; combined: 0.202, 0.155-0.250) or urate fractional renal clearance (allopurinol alone: 0.066, 0.032-0.099; combined: 0.058, 0.038-0.078). CONCLUSIONS A single, low-dose of aspirin or an anti-hypertensive dose of hydrochlorothiazide, when administered alone or together with allopurinol, are unlikely to alter the hypouricaemic effect of allopurinol. The effect of chronic aspirin and HCTZ dosing taken together upon the efficacy of chronic allopurinol therapy in patients with hyperuricaemia needs to be investigated.
Collapse
Affiliation(s)
- Daniel Y Ng
- Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital, Xavier Level 2, Darlinghurst, NSW 2010, Australia
| | | | | | | | | |
Collapse
|
153
|
Abstract
Gout is the most prevalent form of inflammatory arthropathy. Several studies suggest that its prevalence and incidence have risen in recent decades. Numerous risk factors for the development of gout have been established, including hyperuricaemia, genetic factors, dietary factors, alcohol consumption, metabolic syndrome, hypertension, obesity, diuretic use and chronic renal disease. Osteoarthritis predisposes to local crystal deposition. Gout appears to be an independent risk factor for all-cause mortality and cardiovascular mortality and morbidity, additional to the risk conferred by its association with traditional cardiovascular risk factors.
Collapse
Affiliation(s)
- Edward Roddy
- Arthritis Research UK Primary Care Centre, Primary Care Sciences, Keele University, Staffordshire ST5 5BG, UK.
| | | |
Collapse
|
154
|
Dinour D, Bahn A, Ganon L, Ron R, Geifman-Holtzman O, Knecht A, Gafter U, Rachamimov R, Sela BA, Burckhardt G, Holtzman EJ. URAT1 mutations cause renal hypouricemia type 1 in Iraqi Jews. Nephrol Dial Transplant 2010; 26:2175-81. [DOI: 10.1093/ndt/gfq722] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
155
|
Yang Q, Köttgen A, Dehghan A, Smith AV, Glazer NL, Chen H, Chasman DI, Aspelund T, Eiriksdottir G, Harris TB, Launer L, Nalls M, Hernandez D, Arking DE, Boerwinkle E, Grove ML, Li M, Kao WHL, Chonchol M, Haritunians T, Li G, Lumley T, Psaty BM, Shlipak M, Hwang SJ, Larson MG, O’Donnell CJ, Upadhyay A, van Duijn CM, Hofman A, Rivadeneira F, Stricker B, Uitterlinden AG, Paré G, Parker AN, Ridker PM, Siscovick DS, Gudnason V, Witteman JC, Fox CS, Coresh J. Multiple genetic loci influence serum urate levels and their relationship with gout and cardiovascular disease risk factors. CIRCULATION. CARDIOVASCULAR GENETICS 2010; 3:523-30. [PMID: 20884846 PMCID: PMC3371395 DOI: 10.1161/circgenetics.109.934455] [Citation(s) in RCA: 263] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND Elevated serum urate levels can lead to gout and are associated with cardiovascular risk factors. We performed a genome-wide association study to search for genetic susceptibility loci for serum urate and gout and investigated the causal nature of the associations of serum urate with gout and selected cardiovascular risk factors and coronary heart disease (CHD). METHODS AND RESULTS Meta-analyses of genome-wide association studies (GWAS) were performed in 5 population-based cohorts of the Cohorts for Heart and Aging Research in Genome Epidemiology consortium for serum urate and gout in 28 283 white participants. The effect of the most significant single-nucleotide polymorphism at all genome-wide significant loci on serum urate was added to create a genetic urate score. Findings were replicated in the Women's Genome Health Study (n=22 054). Single-nucleotide polymorphisms at 8 genetic loci achieved genome-wide significance with serum urate levels (P=4×10(-8) to 2×10(-242) in SLC22A11, GCKR, R3HDM2-INHBC region, RREB1, PDZK1, SLC2A9, ABCG2, and SLC17A1). Only 2 loci (SLC2A9, ABCG2) showed genome-wide significant association with gout. The genetic urate score was strongly associated with serum urate and gout (odds ratio, 12.4 per 100 μmol/L; P=3×10(-39)) but not with blood pressure, glucose, estimated glomerular filtration rate, chronic kidney disease, or CHD. The lack of association between the genetic score and the latter phenotypes also was observed in the Women's Genome Health Study. CONCLUSIONS The genetic urate score analysis suggested a causal relationship between serum urate and gout but did not provide evidence for one between serum urate and cardiovascular risk factors and CHD.
Collapse
Affiliation(s)
- Qiong Yang
- Dept of Biostatistics, Boston Univ School of Public Health, Boston, MA
- NHLBI’s Framingham Heart Study, Framingham, MA
| | - Anna Köttgen
- Dept of Epidemiology, Johns Hopkins Univ, Baltimore, MD
| | - Abbas Dehghan
- Dept of Epidemiology, Erasmus Med Ctr, Rotterdam, The Netherlands; Member of the Netherlands Consortium on Healthy Aging (NCHA)
| | | | - Nicole L. Glazer
- Cardiovascular Health Research Unit & Dept of Med, Univ of Washington, Seattle, WA
| | - Huei Chen
- NHLBI’s Framingham Heart Study, Framingham, MA
- Dept of Neurology, Boston Univ, Boston, MA
| | - Daniel I. Chasman
- Division of Preventive Med, Brigham and Women’s Hospital, Boston, MA
| | - Thor Aspelund
- Icelandic Heart Association, Kopavogur, Iceland
- Univ of Iceland, Reykjavik, Iceland
| | | | - Tamara B. Harris
- Lab of Epidemiology, Demography, & Biometry, Intramural Research Program, Nat Institute on Aging
| | - Lenore Launer
- Lab of Epidemiology, Demography, & Biometry, Intramural Research Program, Nat Institute on Aging
| | - Michael Nalls
- Lab of Neurogenetics, Intramural Research Program, Nat Institute on Aging
| | - Dena Hernandez
- Lab of Neurogenetics, Intramural Research Program, Nat Institute on Aging
| | - Dan E Arking
- McKusick-Nathans Inst of Genetic Med, Johns Hopkins Med Inst, Baltimore, MD
| | - Eric Boerwinkle
- Human Genetics Ctr & Division of Epidemiology, Univ of Texas Health Science Ctr at Houston, Houston, TX
| | - Megan L. Grove
- Human Genetics Ctr, Univ of Texas Health Science Ctr at Houston, Houston, TX
| | - Man Li
- Dept of Epidemiology, Johns Hopkins Univ, Baltimore, MD
| | - WH Linda Kao
- Dept of Epidemiology, Johns Hopkins Univ, Baltimore, MD
- Dept of Med, Johns Hopkins Univ, Baltimore, MD
| | - Michel Chonchol
- Univ of Colorado Denver Health Sciences Ctr, Division of Renal Diseases & Hypertension; Aurora, CO
| | | | - Guo Li
- Cardiovascular Health Research Unit & Dept of Med, Univ of Washington, Seattle, WA
| | - Thomas Lumley
- Dept of Biostatistics, Univ of Washington, Seattle, WA
| | - Bruce M. Psaty
- Cardiovascular Health Research Unit & Dept of Med, Epidemiology and Health Services, Univ of Washington, Seattle, WA, Center for Health Studies, Group Health, Seattle, WA
| | - Michael Shlipak
- General Internal Med Division; San Francisco VA Med Ctr; Univ of California, San Francisco, CA
| | - Shih-Jen Hwang
- NHLBI’s Framingham Heart Study, Framingham, MA
- The Ctr for Population Studies, NHLBI, Bethesda MD
| | - Martin G. Larson
- NHLBI’s Framingham Heart Study, Framingham, MA
- Dept of Mathematics & Statistics, Boston Univ, Boston, MA
| | - Christopher J. O’Donnell
- NHLBI’s Framingham Heart Study, Framingham, MA
- Cardiology Division, Massachusetts General Hosp, Boston, MA
| | - Ashish Upadhyay
- Renal Section, Boston Med Ctr & Boston Univ School of Med, Boston, MA
| | - Cornelia M. van Duijn
- Dept of Epidemiology, Erasmus Med Ctr, Rotterdam, The Netherlands; Member of the Netherlands Consortium on Healthy Aging (NCHA)
| | - Albert Hofman
- Dept of Epidemiology, Erasmus Med Ctr, Rotterdam, The Netherlands; Member of the Netherlands Consortium on Healthy Aging (NCHA)
| | - Fernando Rivadeneira
- Dept of Internal Med, Erasmus Med Ctr, Rotterdam, The Netherlands; Member of the Netherlands Consortium on Healthy Aging (NCHA)
| | - Bruno Stricker
- Dept of Epidemiology, Erasmus Med Ctr, Rotterdam, The Netherlands; Member of the Netherlands Consortium on Healthy Aging (NCHA)
| | - Andre G. Uitterlinden
- Dept of Internal Med, Erasmus Med Ctr, Rotterdam, The Netherlands; Member of the Netherlands Consortium on Healthy Aging (NCHA)
| | - Guillaume Paré
- Division of Preventive Med, Brigham and Women’s Hospital, Boston, MA
| | | | - Paul M Ridker
- Division of Preventive Med, Brigham and Women’s Hospital, Boston, MA
| | - David S. Siscovick
- Cardiovascular Health Research Unit & Dept of Med & Epidemiology, Univ of Washington, Seattle, WA
| | - Vilmundur Gudnason
- Icelandic Heart Association, Kopavogur, Iceland
- Univ of Iceland, Reykjavik, Iceland
| | - Jacqueline C. Witteman
- Dept of Epidemiology, Erasmus Med Ctr, Rotterdam, The Netherlands; Member of the Netherlands Consortium on Healthy Aging (NCHA)
| | - Caroline S. Fox
- NHLBI’s Framingham Heart Study, Framingham, MA
- The Ctr for Population Studies, NHLBI, Bethesda MD
- Division of Endocrinology, Hypertension, & Metabolism, Brigham and Women’s Hosp & Harvard Med School, Boston, MA
| | - Josef Coresh
- Dept of Epidemiology, Johns Hopkins Univ, Baltimore, MD
- Dept of Med, Johns Hopkins Univ, Baltimore, MD
- Dept of Biostatistics, Johns Hopkins Univ, Baltimore, MD
| |
Collapse
|
156
|
Kanbara A, Hakoda M, Seyama I. Urine alkalization facilitates uric acid excretion. Nutr J 2010; 9:45. [PMID: 20955624 PMCID: PMC2976726 DOI: 10.1186/1475-2891-9-45] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2010] [Accepted: 10/19/2010] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Increase in the incidence of hyperuricemia associated with gout as well as hypertension, renal diseases and cardiovascular diseases has been a public health concern. We examined the possibility of facilitated excretion of uric acid by change in urine pH by managing food materials. METHODS Within the framework of the Japanese government's health promotion program, we made recipes which consist of protein-rich and less vegetable-fruit food materials for H+-load (acid diet) and others composed of less protein but vegetable-fruit rich food materials (alkali diet). Healthy female students were enrolled in this consecutive 5-day study for each test. From whole-day collected urine, total volume, pH, organic acid, creatinine, uric acid and all cations (Na+,K+,Ca(2+),Mg(2+),NH₄+) and anions (Cl⁻,SO₄(2-),PO₄⁻) necessary for the estimation of acid-base balance were measured. RESULTS Urine pH reached a steady state 3 days after switching from ordinary daily diets to specified regimens. The amount of acid generated ([SO₄(2-)] +organic acid-gut alkai) were linearly related with those of the excretion of acid (titratable acidity+ [NH4+] - [HCO3⁻]), indicating that H+ in urine is generated by the metabolic degradation of food materials. Uric acid and excreted urine pH retained a linear relationship, where uric acid excretion increased from 302 mg/day at pH 5.9 to 413 mg/day at pH 6.5, despite the fact that the alkali diet contained a smaller purine load than the acid diet. CONCLUSION We conclude that alkalization of urine by eating nutritionally well-designed food is effective for removing uric acid from the body.
Collapse
Affiliation(s)
- Aya Kanbara
- Department of Nutrition and Health Promotion, Faculty for Human Development, Hiroshima Jyogakuin University. 4-13-1 Ushita-higashi Higashi-ku Hiroshima 732-0063 Japan
| | - Masayuki Hakoda
- Department of Nutritional Sciences, Faculty of Human Ecology, Yasuda Women's University. 6-13-1 Yasuhigashi, Asaminami-ku, Hiroshima 731-0153 Japan
| | - Issei Seyama
- Department of Nutrition and Health Promotion, Faculty for Human Development, Hiroshima Jyogakuin University. 4-13-1 Ushita-higashi Higashi-ku Hiroshima 732-0063 Japan
| |
Collapse
|
157
|
Assessment of the role of renal organic anion transporters in drug-induced nephrotoxicity. Toxins (Basel) 2010; 2:2055-82. [PMID: 22069672 PMCID: PMC3153278 DOI: 10.3390/toxins2082055] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Revised: 08/05/2010] [Accepted: 08/05/2010] [Indexed: 01/09/2023] Open
Abstract
In the present review we have attempted to assess the involvement of the organic anion transporters OAT1, OAT2, OAT3, and OAT4, belonging to the SLC22 family of polyspecific carriers, in drug-induced renal damage in humans. We have focused on drugs with widely recognized nephrotoxic potential, which have previously been reported to interact with OAT family members, and whose underlying pathogenic mechanism suggests the participation of tubular transport. Thus, only compounds generally believed to cause kidney injury either by means of direct tubular toxicity or crystal nephropathy have been considered. For each drug, or class of agents, the evidence for actual transport mediated by individual OATs under in vivo conditions is discussed. We have then examined their role in the context of other carriers present in the renal proximal tubule sharing certain substrates with OATs, as these are critical determinants of the overall contribution of OAT-dependent transport to intracellular accumulation and transepithelial drug secretion, and thus the impact it may have in drug-induced nephrotoxicity.
Collapse
|
158
|
Shima JE, Komori T, Taylor TR, Stryke D, Kawamoto M, Johns SJ, Carlson EJ, Ferrin TE, Giacomini KM. Genetic variants of human organic anion transporter 4 demonstrate altered transport of endogenous substrates. Am J Physiol Renal Physiol 2010; 299:F767-75. [PMID: 20668102 DOI: 10.1152/ajprenal.00312.2010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Apical reabsorption from the urine has been shown to be important for such processes as the maintenance of critical metabolites in the blood and the excretion of nephrotoxic compounds. The solute carrier (SLC) transporter OAT4 (SLC22A11) is expressed on the apical membrane of renal proximal tubule cells and is known to mediate the transport of a variety of xenobiotic and endogenous organic anions. Functional characterization of genetic variants of apical transporters thought to mediate reabsorption, such as OAT4, may provide insight into the genetic factors influencing the complex pathways involved in drug elimination and metabolite reclamation occurring in the kidney. Naturally occurring genetic variants of OAT4 were identified in public databases and by resequencing DNA samples from 272 individuals comprising 4 distinct ethnic groups. Nine total nonsynonymous variants were identified and functionally assessed using uptake of three radiolabeled substrates. A nonsense variant, R48Stop, and three other variants (R121C, V155G, and V155M) were found at frequencies of at least 2% in an ethnic group specific fashion. The L29P, R48Stop, and H469R variants displayed a complete loss of function, and kinetic analysis identified a reduced V(max) in the common nonsynonymous variants. Plasma membrane levels of OAT4 protein were absent or reduced in the nonfunctional variants, providing a mechanistic reason for the observed loss of function. Characterization of the genetic variants of reabsorptive transporters such as OAT4 is an important step in understanding variability in tubular reabsorption with important implications in innate homeostatic processes and drug disposition.
Collapse
Affiliation(s)
- James E Shima
- Dept. of Bioengineering and Therapeutics Sciences, University of California, San Francisco, California 94143-2911, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
159
|
Yang CH, Glover KP, Han X. Characterization of cellular uptake of perfluorooctanoate via organic anion-transporting polypeptide 1A2, organic anion transporter 4, and urate transporter 1 for their potential roles in mediating human renal reabsorption of perfluorocarboxylates. Toxicol Sci 2010; 117:294-302. [PMID: 20639259 DOI: 10.1093/toxsci/kfq219] [Citation(s) in RCA: 130] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
It has been hypothesized that human renal apical membrane transporters play a key role in human renal reabsorption of perfluorooctanoate (PFO), which contributes to the long half-life of PFO in humans. In the present study, PFO uptake kinetics of human organic anion-transporting polypeptide (OATP) 1A2, organic anion transporter (OAT) 4, and urate transporter 1 (URAT1) in stably transfected cell lines was investigated. OAT4 and URAT1, but not OATP1A2, were shown to mediate saturable PFO cellular uptake. OAT4-mediated PFO uptake was stimulated by a low extracellular pH, which was evidenced as a lower Michaelis constant (K(m)) at pH 6 (172.3 ± 45.9μM) than that at pH 7.4 (310.3 ± 30.2μM). URAT1-mediated PFO uptake was greatly enhanced by an outward Cl(-) gradient, and its K(m) value was determined to be 64.1 ± 30.5μM in the absence of extracellular Cl(-). The inhibition of OATP1A2- or OAT4-mediated estrone-3-sulfate uptake or URAT1-mediated urate uptake has been compared for linear perfluorocarboxylates (PFCs) with carbon chain lengths from 4 to 12. A clear chain length-dependent inhibition was observed, suggesting that PFCs in general are substrates of OAT4 and URAT1 but with different levels of affinities to the transporters depending on their chain length. Our results suggest that OAT4 and URAT1 are key transporters in renal reabsorption of PFCs in humans and, as a result, may contribute significantly to the long half-life of PFO in humans.
Collapse
Affiliation(s)
- Ching-Hui Yang
- DuPont Haskell Global Centers for Health & Environmental Sciences, Newark, Delaware 19714, USA
| | | | | |
Collapse
|
160
|
Abstract
Uric acid is the metabolic end product of purine metabolism in humans. It has antioxidant properties that may be protective but can also be pro-oxidant, depending on its chemical microenvironment. Hyperuricemia predisposes to disease through the formation of urate crystals that cause gout, but hyperuricemia, independent of crystal formation, has also been linked with hypertension, atherosclerosis, insulin resistance, and diabetes. We discuss here the biology of urate metabolism and its role in disease. We also cover the genetics of urate transport, including URAT1, and recent studies identifying SLC2A9, which encodes the glucose transporter family isoform Glut9, as a major determinant of plasma uric acid levels and of gout development.
Collapse
Affiliation(s)
- Alexander So
- Service de Rhumatologie, Department of Musculoskeletal Medicine, University of Lausanne, Lausanne, Switzerland
| | | |
Collapse
|
161
|
Yang Z, Xiaohua W, Lei J, Ruoyun T, Mingxia X, Weichun H, Li F, Ping W, Junwei Y. Uric acid increases fibronectin synthesis through upregulation of lysyl oxidase expression in rat renal tubular epithelial cells. Am J Physiol Renal Physiol 2010; 299:F336-46. [PMID: 20484295 DOI: 10.1152/ajprenal.00053.2010] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Urate is produced as the major end product of purine metabolism. In the last decade, the incidence of hyperuricemia increased markedly, and similar trends in the epidemiology of metabolic syndrome have been observed. Hyperuricemia is associated with renal disease, and recent studies have reported that mild hyperuricemia results in hypertension, intrarenal vascular disease, and renal injury. This has led to the hypothesis that uric acid may contribute to renal fibrosis and progressive renal disease. Our purpose was to investigate the relationship between uric acid and renal tubular injury. We applied the method of intraperitoneal injection of uric acid to generate the hyperuricemic mouse model. Compared with the saline injection group, the expression of lysyl oxidase (LOX) and fibronectin in kidneys was increased significantly in hyperuricemic groups. In vitro, uric acid significantly induced NRK-52E cells to express the ECM marker fibronectin, as well as LOX, which plays a pivotal role in ECM maturation, in a time- and dose-dependent manner. Upregulation of the urate transporter URAT1, which is located in the apical membrane of proximal tubules, sensitized the uric acid-induced fibronectin and LOX induction, while both knocking down URAT1 expression in tubular epithelial cells by RNA interference and inhibiting URAT1 function pharmacologically attenuated LOX and fibronectin expression. Furthermore, knockdown of LOX expression by a small interfering RNA strategy led to a decrease in fibronectin abundance induced by uric acid treatment. In addition, evidence of a uric acid-induced activation of the NF-kappaB signaling cascade was observed. Our findings highlight a need for carefully reevaluating our previous view on the pathological roles of hyperuricemia in the kidney and nephropathy induced by uric acid in clinical practice.
Collapse
Affiliation(s)
- Zhou Yang
- Center of Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, China
| | | | | | | | | | | | | | | | | |
Collapse
|
162
|
Merriman TR, Dalbeth N. The genetic basis of hyperuricaemia and gout. Joint Bone Spine 2010; 78:35-40. [PMID: 20472486 DOI: 10.1016/j.jbspin.2010.02.027] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Accepted: 02/10/2010] [Indexed: 12/14/2022]
Abstract
Gout results from elevated urate concentrations in the blood (hyperuricaemia). When super-saturation of urate is reached, monosodium urate crystals form within the joint. In some individuals, these crystals elicit a painful self-limiting inflammatory response that is characteristic of acute gouty arthritis. The most important cause of hyperuricaemia is reduced excretion of uric acid in the urine. Uric acid excretion is coordinated by a suite of urate transport molecules expressed in the renal collecting tubules, and is a key physiological checkpoint in gout. Other checkpoints in gout are hepatic production of urate, monosodium urate crystal formation, and initiation of the acute inflammatory response. Genome-wide association scans for genes regulating serum urate concentrations have identified two major regulators of hyperuricaemia- the renal urate transporters SLC2A9 and ABCG2. The risk variants at each gene approximately double the risk for gout in people of Caucasian ancestry, with SLC2A9 also resulting in higher risk for gout in people of Polynesian ancestry, a diverse population characterized by a high prevalence of gout. Ongoing genetic association studies are identifying and confirming other genes controlling serum urate concentrations; although genome-wide association studies in gout per se await recruitment of suitable case sample sets.
Collapse
Affiliation(s)
- Tony R Merriman
- Department of Biochemistry, University of Otago, PO Box 56, Dunedin, New Zealand.
| | | |
Collapse
|
163
|
VanWert AL, Gionfriddo MR, Sweet DH. Organic anion transporters: discovery, pharmacology, regulation and roles in pathophysiology. Biopharm Drug Dispos 2010; 31:1-71. [PMID: 19953504 DOI: 10.1002/bdd.693] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Our understanding of the mechanisms behind inter- and intra-patient variability in drug response is inadequate. Advances in the cytochrome P450 drug metabolizing enzyme field have been remarkable, but those in the drug transporter field have trailed behind. Currently, however, interest in carrier-mediated disposition of pharmacotherapeutics is on a substantial uprise. This is exemplified by the 2006 FDA guidance statement directed to the pharmaceutical industry. The guidance recommended that industry ascertain whether novel drug entities interact with transporters. This suggestion likely stems from the observation that several novel cloned transporters contribute significantly to the disposition of various approved drugs. Many drugs bear anionic functional groups, and thus interact with organic anion transporters (OATs). Collectively, these transporters are nearly ubiquitously expressed in barrier epithelia. Moreover, several reports indicate that OATs are subject to diverse forms of regulation, much like drug metabolizing enzymes and receptors. Thus, critical to furthering our understanding of patient- and condition-specific responses to pharmacotherapy is the complete characterization of OAT interactions with drugs and regulatory factors. This review provides the reader with a comprehensive account of the function and substrate profile of cloned OATs. In addition, a major focus of this review is on the regulation of OATs including the impact of transcriptional and epigenetic factors, phosphorylation, hormones and gender.
Collapse
Affiliation(s)
- Adam L VanWert
- Department of Pharmaceutical Sciences, Wilkes University, Wilkes-Barre, PA 18766, USA
| | | | | |
Collapse
|
164
|
McDermott JR, Jiang X, Beene LC, Rosen BP, Liu Z. Pentavalent methylated arsenicals are substrates of human AQP9. Biometals 2010; 23:119-27. [PMID: 19802720 PMCID: PMC4266138 DOI: 10.1007/s10534-009-9273-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2009] [Accepted: 09/22/2009] [Indexed: 01/08/2023]
Abstract
Liver aquaglyceroporin AQP9 facilitates movement of trivalent inorganic arsenite (As(III)) and organic monomethylarsonous acid (MAs(III)). However, the transport pathway for the two major pentavalent arsenic cellular metabolites, MAs(V) and DMAs(V), remains unknown in mammals. These products of arsenic metabolism, in particular DMAs(V), are the major arsenicals excreted in the urine of mammals. In this study, we examined the uptake of the two pentavalent organic arsenicals by human AQP9 in Xenopus laevis oocytes. Xenopus laevis oocytes microinjected with AQP9 cRNA exhibited uptake of both MAs(V) and DMAs(V) in a pH-dependent manner. The rate of transport was much higher at acidic pH (pH5.5) than at neutral pH. Hg(II), an aquaporin inhibitor, inhibited transport of As(III), MAs(III), MAs(V) and DMAs(V) via AQP9. However, phloretin, which inhibits water and glycerol permeation via AQP9, can only inhibit transport of pentavalent MAs(V) and DMAs(V) but not trivalent As(III) and MAs(III), indicating the translocation mechanisms of these arsenic species are not exactly the same. Reagents such as FCCP, valinomycin and nigericin that dissipate transmembrane proton potential or change the transmemebrane pH gradient did not significantly inhibit all arsenic transport via AQP9, suggesting the transport of pentavalent arsenic is not proton coupled. The results suggest that in addition to the initial uptake of trivalent inorganic As(III) inside cells, AQP9 plays a dual role in the detoxification of arsenic metabolites by facilitating efflux from cells.
Collapse
Affiliation(s)
- Joseph R. McDermott
- Department of Biological Sciences, Oakland University, Dodge Hall 325, 2200 N. Squirrel Rd, Rochester, MI 48309, USA
| | - Xuan Jiang
- Departments of Biochemistry and Molecular Biology, School of Medicine, Wayne State University, 540 E. Canfield Ave, Detroit, MI 48201, USA
| | - Lauren C. Beene
- Department of Biological Sciences, Oakland University, Dodge Hall 325, 2200 N. Squirrel Rd, Rochester, MI 48309, USA
| | - Barry P. Rosen
- Departments of Biochemistry and Molecular Biology, School of Medicine, Wayne State University, 540 E. Canfield Ave, Detroit, MI 48201, USA; Florida International University, College of Medicine, 11200 SW 8th Street, HLS II 693, Miami, FL 33199, USA
| | - Zijuan Liu
- Department of Biological Sciences, Oakland University, Dodge Hall 325, 2200 N. Squirrel Rd, Rochester, MI 48309, USA
| |
Collapse
|
165
|
Sato M, Mamada H, Anzai N, Shirasaka Y, Nakanishi T, Tamai I. Renal Secretion of Uric Acid by Organic Anion Transporter 2 (OAT2/SLC22A7) in Human. Biol Pharm Bull 2010; 33:498-503. [DOI: 10.1248/bpb.33.498] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Masanobu Sato
- Kanazawa University, Institute of Medical, Pharmaceutical and Health Sciences, Faculty of Pharmacy
| | - Hideaki Mamada
- Kanazawa University, Institute of Medical, Pharmaceutical and Health Sciences, Faculty of Pharmacy
| | - Naohiko Anzai
- Department of Pharmacology and Toxicology, Kyorin University School of Medicine
| | - Yoshiyuki Shirasaka
- Kanazawa University, Institute of Medical, Pharmaceutical and Health Sciences, Faculty of Pharmacy
| | - Takeo Nakanishi
- Kanazawa University, Institute of Medical, Pharmaceutical and Health Sciences, Faculty of Pharmacy
| | - Ikumi Tamai
- Kanazawa University, Institute of Medical, Pharmaceutical and Health Sciences, Faculty of Pharmacy
| |
Collapse
|
166
|
Abstract
Many factors, including genetic components and acquired factors such as obesity and alcohol consumption, influence serum uric acid (urate) concentrations. Since serum urate concentrations are determined by the balance between renal urate excretion and the volume of urate produced via purine metabolism, urate transporter genes as well as genes coding for enzymes involved in purine metabolism affect serum urate concentrations. URAT1 was the first transporter affecting serum urate concentrations to be identified. Using the characterization of this transporter as an indicator, several transporters have been shown to transport urate, allowing the construction of a synoptic renal urate transport model. Notable re-absorptive urate transporters are URAT1 at apical membranes and GLUT9 at basolateral membranes, while ABCG2, MRP4 (multidrug resistance protein 4) and NPT1 are secretive transporters at apical membranes. Recent genome-wide association studies have led to validation of the in vitro model constructed from each functional analysis of urate transporters, and identification of novel candidate genes related to urate metabolism and transport proteins, such as glucokinase regulatory protein (GKRP), PDZK1 and MCT9. However, the function and physiologic roles of several candidates, as well as the influence of acquired factors such as obesity, foods, or alcoholic beverages, remain unclear.
Collapse
|
167
|
Dinour D, Gray NK, Campbell S, Shu X, Sawyer L, Richardson W, Rechavi G, Amariglio N, Ganon L, Sela BA, Bahat H, Goldman M, Weissgarten J, Millar MR, Wright AF, Holtzman EJ. Homozygous SLC2A9 mutations cause severe renal hypouricemia. J Am Soc Nephrol 2009; 21:64-72. [PMID: 19926891 DOI: 10.1681/asn.2009040406] [Citation(s) in RCA: 168] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Hereditary hypouricemia may result from mutations in the renal tubular uric acid transporter URAT1. Whether mutation of other uric acid transporters produces a similar phenotype is unknown. We studied two families who had severe hereditary hypouricemia and did not have a URAT1 defect. We performed a genome-wide homozygosity screen and linkage analysis and identified the candidate gene SLC2A9, which encodes the glucose transporter 9 (GLUT9). Both families had homozygous SLC2A9 mutations: A missense mutation (L75R) in six affected members of one family and a 36-kb deletion, resulting in a truncated protein, in the other. In vitro, the L75R mutation dramatically impaired transport of uric acid. The mean concentration of serum uric acid of seven homozygous individuals was 0.17 +/- 0.2 mg/dl, and all had a fractional excretion of uric acid >150%. Three individuals had nephrolithiasis, and three had a history of exercise-induced acute renal failure. In conclusion, homozygous loss-of-function mutations of GLUT9 cause a total defect of uric acid absorption, leading to severe renal hypouricemia complicated by nephrolithiasis and exercise-induced acute renal failure. In addition to clarifying renal handling of uric acid, our findings may provide a better understanding of the pathophysiology of acute renal failure, nephrolithiasis, hyperuricemia, and gout.
Collapse
Affiliation(s)
- Dganit Dinour
- Nephrology and Hypertension Institute, Sheba Medical Center, Tel-Hashomer, 52621, Israel.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
168
|
Abstract
PURPOSE OF REVIEW The goal of this article is to review the possible physiological roles of the recently identified urate transporter, solute carrier family 2 (facilitated glucose transporter), member 9 (SLC2A9), in the renal handling of urate. RECENT FINDINGS Glucose transporter 9 is a high affinity hexose transporter encoded by the SLC2A9 gene found on human chromosome 4. The two splice variants SLC2A9b and SLC2A9a are expressed in the apical and basolateral membranes, respectively, of the proximal convoluted tubule. Recent reports have found significant correlations between two different sets of single nucleotide polymorphisms in SLC2A9. In one case, they are associated with increases in plasma urate levels and/or the incidence of hypertension or gout. The second set of single nucleotide polymorphisms correlate with hypouricaemia in Japanese patients. Expression of SLC2A9a and b in Xenopus laevis oocytes shows that these proteins mediate rapid urate fluxes and can exchange glucose for urate. Indirect evidence also suggests that the transporter is electrogenic. SUMMARY This review proposes that SLC2A9 contributes significantly in two ways to the fluxes of urate across the proximal convoluted tubule. Firstly, the apical expression of SLC2A9b secretes urate back into the urine in exchange for lumenal glucose. Secondly, the basolateral membrane SLC2A9a could be the primary route for urate movement out of the epithelium into the peritubular space.
Collapse
|
169
|
Glut9 is a major regulator of urate homeostasis and its genetic inactivation induces hyperuricosuria and urate nephropathy. Proc Natl Acad Sci U S A 2009; 106:15501-6. [PMID: 19706426 DOI: 10.1073/pnas.0904411106] [Citation(s) in RCA: 187] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Elevated plasma urate levels are associated with metabolic, cardiovascular, and renal diseases. Urate may also form crystals, which can be deposited in joints causing gout and in kidney tubules inducing nephrolithiasis. In mice, plasma urate levels are controlled by hepatic breakdown, as well as, by incompletely understood renal processes of reabsorption and secretion. Here, we investigated the role of the recently identified urate transporter, Glut9, in the physiological control of urate homeostasis using mice with systemic or liver-specific inactivation of the Glut9 gene. We show that Glut9 is expressed in the basolateral membrane of hepatocytes and in both apical and basolateral membranes of the distal nephron. Mice with systemic knockout of Glut9 display moderate hyperuricemia, massive hyperuricosuria, and an early-onset nephropathy, characterized by obstructive lithiasis, tubulointerstitial inflammation, and progressive inflammatory fibrosis of the cortex, as well as, mild renal insufficiency. In contrast, liver-specific inactivation of the Glut9 gene in adult mice leads to severe hyperuricemia and hyperuricosuria, in the absence of urate nephropathy or any structural abnormality of the kidney. Together, our data show that Glut9 plays a major role in urate homeostasis by its dual role in urate handling in the kidney and uptake in the liver.
Collapse
|
170
|
Bakhiya N, Arlt VM, Bahn A, Burckhardt G, Phillips DH, Glatt H. Molecular evidence for an involvement of organic anion transporters (OATs) in aristolochic acid nephropathy. Toxicology 2009; 264:74-9. [PMID: 19643159 DOI: 10.1016/j.tox.2009.07.014] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2009] [Revised: 07/19/2009] [Accepted: 07/20/2009] [Indexed: 02/02/2023]
Abstract
Aristolochic acid (AA), present in Aristolochia species, is the major causative agent in the development of severe renal failure and urothelial cancers in patients with AA nephropathy. It may also be a cause of Balkan endemic nephropathy. Epithelial cells of the proximal tubule are the primary cellular target of AA. To study whether organic anion transporters (OATs) expressed in proximal tubule cells are involved in uptake of AA, we used human epithelial kidney (HEK293) cells stably expressing human (h) OAT1, OAT3 or OAT4. AA potently inhibited the uptake of characteristic substrates, p-aminohippurate for hOAT1 and estrone sulfate for hOAT3 and hOAT4. Aristolochic acid I (AAI), the more cytotoxic and genotoxic AA congener, exhibited high affinity for hOAT1 (K(i)=0.6 microM) as well as hOAT3 (K(i)=0.5 microM), and lower affinity for hOAT4 (K(i)=20.6 microM). Subsequently, AAI-DNA adduct formation (investigated by (32)P-postlabelling) was used as a measure of AAI uptake. Significantly higher levels of adducts occurred in hOAT-expressing cells than in control cells: this effect was abolished in the presence of the OAT inhibitor probenecid. In Xenopus laevis oocytes hOAT-mediated efflux of p-aminohippurate was trans-stimulated by extracellular AA, providing further molecular evidence for AA translocation by hOATs. Our study indicates that OATs can mediate the uptake of AA into proximal tubule cells and thereby participate in kidney cell damage by this toxin.
Collapse
Affiliation(s)
- Nadiya Bakhiya
- German Institute of Human Nutrition (DIfE) Potsdam-Rehbrücke, Department of Nutritional Toxicology, Arthur-Scheunert-Allee 114-116, 14558 Nuthetal, Germany
| | | | | | | | | | | |
Collapse
|
171
|
Ouellet G, Lin SH, Nolin L, Bonnardeaux A. [Hereditary renal hypouricemia in a Caucasian patient: a case report and review of the literature]. Nephrol Ther 2009; 5:568-71. [PMID: 19464979 DOI: 10.1016/j.nephro.2009.03.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2008] [Revised: 03/18/2009] [Accepted: 03/18/2009] [Indexed: 11/25/2022]
Abstract
Hereditary renal hypouricemia is characterized by a decreased serum uric acid, a uric acid fractional excretion above normal and the absence of another cause of hyperuricosuric hypouricemia. This pathology, generally caused by a mutation of urate renal transporter URAT1, is relatively common in Asia, but occurs very infrequently in Caucasian populations. The disease's association with exercise-induced acute renal failure is well known. This article reports the case of a 47-year-old man of Italian origin who was diagnosed with hereditary renal hypouricemia after an episode of exercise-induced acute renal failure. Molecular analysis of SLC22A12 encoding URAT1 for renal hypouricemia using peripheral blood genomic DNA of the patient was performed. Single-strand conformation polymorphism screening, amplification, and direct sequencing of SLC22A12 revealed no mutation in this patient. This suggests that another gene can be involved in this disease.
Collapse
Affiliation(s)
- Georges Ouellet
- Service de néphrologie, hôpital Maisonneuve-Rosemont, Montréal, Québec H1T 2M4, Canada
| | | | | | | |
Collapse
|
172
|
|
173
|
Effect of hypouricaemic and hyperuricaemic drugs on the renal urate efflux transporter, multidrug resistance protein 4. Br J Pharmacol 2008; 155:1066-75. [PMID: 18724382 DOI: 10.1038/bjp.2008.343] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND AND PURPOSE The xanthine oxidase inhibitors allopurinol and oxypurinol are used to treat hyperuricaemia, whereas loop and thiazide diuretics can cause iatrogenic hyperuricaemia. Some uricosuric drugs and salicylate have a bimodal action on urate renal excretion. The mechanisms of action of these hypo- and hyperuricaemic drugs on the handling of urate in renal tubules have not been fully elucidated. Recently, we identified the multidrug resistance protein (MRP) 4 as a luminal efflux transporter for urate in the proximal tubule. EXPERIMENTAL APPROACH Here, we studied the effect of these drugs on [(14)C]urate transport using human embryonic kidney 293 cells overexpressing human MRP4 and in membrane vesicles isolated from these cells. KEY RESULTS Allopurinol stimulated MRP4-mediated cellular urate efflux and allopurinol and oxypurinol both markedly stimulated urate transport by MRP4 in membrane vesicles. Bumetanide and torasemide had no effect, whereas furosemide, chlorothiazide, hydrochlorothiazide, salicylate, benzbromarone and sulfinpyrazone inhibited urate transport, at concentrations ranging from nanomolar up to millimolar. Probenecid stimulated urate transport at 0.1 microM and inhibited transport at higher concentrations. CONCLUSIONS AND IMPLICATIONS These data suggest that inhibition of MRP4-mediated urate efflux by furosemide and thiazide diuretics could have an important function in their hyperuricaemic mechanisms. Furthermore, stimulation of MRP4-mediated renal urate efflux could be a new mechanism in the hypouricaemic action of allopurinol and oxypurinol. In conclusion, MRP4 may provide a potential target for drugs affecting urate homoeostasis, which needs to be further evaluated in vivo.
Collapse
|
174
|
Ugele B, Bahn A, Rex-Haffner M. Functional differences in steroid sulfate uptake of organic anion transporter 4 (OAT4) and organic anion transporting polypeptide 2B1 (OATP2B1) in human placenta. J Steroid Biochem Mol Biol 2008; 111:1-6. [PMID: 18501590 DOI: 10.1016/j.jsbmb.2008.04.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2007] [Revised: 04/01/2008] [Accepted: 04/01/2008] [Indexed: 11/30/2022]
Abstract
Human trophoblasts depend on the supply of external precursors such as dehydroepiandrosterone-3-sulfate (DHEA-S) and 16alpha-OH-DHEA-S for synthesis of estrogens. Recently, we have characterized the uptake of DHEA-S by isolated mononucleated trophoblasts and identified different transporter polypeptides involved in this process. Immunohistochemistry of 1st and 3rd trimester placenta detected organic anion transporter 4 (OAT4) and organic anion transporting polypeptide 2B1 (OATP2B1, former name OATP-B) in cytotrophoblast membranes and at the basal surface of the syncytiotrophoblast, indicating that both transporter polypeptides are involved in placental uptake of foetal derived steroid sulfates. In the present study we have characterized and compared the kinetics of DHEA-S and estrone sulfate (E(1)S) uptake by these transporters stably expressed in FlpIn -HEK293 cells using the Flp recombinase-mediated site-specific recombination. Uptake of E(1)S by OAT4- and OATP2B1-transfected cells was highly increased compared to the non-transfected cells. In contrast, DHEA-S uptake was only highly increased in OAT4 (40 times), but only weakly enhanced in OATP2B1 cells. The uptake of DHEA-S and E(1)S by OAT4 was partly Na(+)-dependent (about 50%), whereas uptake of DHEA-S by OATP2B1 was Na(+)-independent. Kinetic analysis of the initial uptake rates of E(1)S by OAT4 and OATP2B1 gave very similar values for K(m) (about 20microM) and V(max) (about 600pmol/(minxmg protein)). In contrast, the affinity of DHEA-S towards OATP2B1 was about 10 times lower (K(m)>200microM) then for OAT4 (K(m)=29microM). Our results suggest different physiological roles of the two transporter polypeptides in placental uptake of foetal derived steroid sulfates. OATP2B1 seems not to be involved in de novo synthesis of placental estrogens but may contribute to the clearance of estrogen sulfates from foetal circulation.
Collapse
Affiliation(s)
- Bernhard Ugele
- Klinikum der Universität München, Lindwurmstr. 2a, D-80337 München, Germany.
| | | | | |
Collapse
|
175
|
Mechanisms of renal anionic drug transport. Eur J Pharmacol 2008; 585:245-55. [DOI: 10.1016/j.ejphar.2008.02.085] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2007] [Revised: 02/08/2008] [Accepted: 02/20/2008] [Indexed: 01/11/2023]
|
176
|
Bahn A, Hagos Y, Reuter S, Balen D, Brzica H, Krick W, Burckhardt BC, Sabolic I, Burckhardt G. Identification of a new urate and high affinity nicotinate transporter, hOAT10 (SLC22A13). J Biol Chem 2008; 283:16332-41. [PMID: 18411268 DOI: 10.1074/jbc.m800737200] [Citation(s) in RCA: 152] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The orphan transporter hORCTL3 (human organic cation transporter like 3; SLC22A13) is highly expressed in kidneys and to a weaker extent in brain, heart, and intestine. hORCTL3-expressing Xenopus laevis oocytes showed uptake of [(3)H]nicotinate, [(3)H]p-aminohippurate, and [(14)C]urate. Hence, hORCTL3 is an organic anion transporter, and we renamed it hOAT10. [(3)H]Nicotinate transport by hOAT10 into X. laevis oocytes and into Caco-2 cells was saturable with Michaelis constants (K(m)) of 22 and 44 microm, respectively, suggesting that hOAT10 may be the molecular equivalent of the postulated high affinity nicotinate transporter in kidneys and intestine. The pH dependence of hOAT10 suggests p-aminohippurate(-)/OH(-), urate(-)/OH(-), and nicotinate(-)/OH(-) exchange as possible transport modes. Urate inhibited [(3)H]nicotinate transport by hOAT10 with an IC(50) value of 759 microm, assuming that hOAT10 represents a low affinity urate transporter. hOAT10-mediated [(14)C]urate uptake was elevated by an exchange with l -lactate, pyrazinoate, and nicotinate. Surprisingly, we have detected urate(-)/glutathione exchange by hOAT10, consistent with an involvement of hOAT10 in the renal glutathione cycle. Uricosurics, diuretics, and cyclosporine A showed substantial interactions with hOAT10, of which cyclosporine A enhanced [(14)C]urate uptake, providing the first molecular evidence for cyclosporine A-induced hyperuricemia.
Collapse
Affiliation(s)
- Andrew Bahn
- Zentrum Physiologie und Pathophysiologie, Abteilung Vegetative Physiologie und Pathophysiologie, Humboldtallee 23, 37073 Göttingen, Germany.
| | | | | | | | | | | | | | | | | |
Collapse
|
177
|
Mühlhausen C, Burckhardt BC, Hagos Y, Burckhardt G, Keyser B, Lukacs Z, Ullrich K, Braulke T. Membrane translocation of glutaric acid and its derivatives. J Inherit Metab Dis 2008; 31:188-93. [PMID: 18404412 DOI: 10.1007/s10545-008-0825-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2007] [Revised: 02/05/2008] [Accepted: 02/13/2008] [Indexed: 10/22/2022]
Abstract
The neurodegenerative disorder glutaric aciduria type I (GA I) is characterized by increased levels of cytotoxic metabolites such as glutaric acid (GA) and 3-hydroxyglutaric (3OHGA). The present report summarizes recent investigations providing insights into mechanisms of intra- and intercellular translocation of these metabolites. Initiated by microarray analyses in a mouse model of GA I, the sodium-dependent dicarboxylate cotransporter 3 (NaC3) was the first molecule identified to mediate the translocation of GA and 3OHGA with high and low affinity, respectively. More recently, organic anion transporters (OAT) 1 and 4 have been reported to be high-affinity transporters for GA and 3OHGA as well as D-2- and L-2-hydroxyglutaric acid (D2OHGA, L2OHGA). The concerted action of NaC3 and OATs may be important for the directed uptake and excretion of GA, 3OHGA, D2OHGA and L2OHGA in kidney proximal tubule cells. In addition, experimental data on cultured neuronal and glial cells isolated from mouse brain demonstrated that GA rather than 3OHGA may competitively inhibit the anaplerotic supply of tricarboxylic acid cycle intermediates from astrocytes to neurons. The identification of GA and GA derivative transporters may represent targets for new approaches to treat patients with GA I and related disorders.
Collapse
Affiliation(s)
- C Mühlhausen
- Department of Pediatrics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
| | | | | | | | | | | | | | | |
Collapse
|
178
|
Organic anion transporters OAT1 and OAT4 mediate the high affinity transport of glutarate derivatives accumulating in patients with glutaric acidurias. Pflugers Arch 2008; 457:223-31. [DOI: 10.1007/s00424-008-0489-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2007] [Revised: 02/08/2008] [Accepted: 02/29/2008] [Indexed: 10/22/2022]
|
179
|
Vitart V, Rudan I, Hayward C, Gray NK, Floyd J, Palmer CNA, Knott SA, Kolcic I, Polasek O, Graessler J, Wilson JF, Marinaki A, Riches PL, Shu X, Janicijevic B, Smolej-Narancic N, Gorgoni B, Morgan J, Campbell S, Biloglav Z, Barac-Lauc L, Pericic M, Klaric IM, Zgaga L, Skaric-Juric T, Wild SH, Richardson WA, Hohenstein P, Kimber CH, Tenesa A, Donnelly LA, Fairbanks LD, Aringer M, McKeigue PM, Ralston SH, Morris AD, Rudan P, Hastie ND, Campbell H, Wright AF. SLC2A9 is a newly identified urate transporter influencing serum urate concentration, urate excretion and gout. Nat Genet 2008; 40:437-42. [PMID: 18327257 DOI: 10.1038/ng.106] [Citation(s) in RCA: 557] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2007] [Accepted: 02/04/2008] [Indexed: 12/13/2022]
Abstract
Uric acid is the end product of purine metabolism in humans and great apes, which have lost hepatic uricase activity, leading to uniquely high serum uric acid concentrations (200-500 microM) compared with other mammals (3-120 microM). About 70% of daily urate disposal occurs via the kidneys, and in 5-25% of the human population, impaired renal excretion leads to hyperuricemia. About 10% of people with hyperuricemia develop gout, an inflammatory arthritis that results from deposition of monosodium urate crystals in the joint. We have identified genetic variants within a transporter gene, SLC2A9, that explain 1.7-5.3% of the variance in serum uric acid concentrations, following a genome-wide association scan in a Croatian population sample. SLC2A9 variants were also associated with low fractional excretion of uric acid and/or gout in UK, Croatian and German population samples. SLC2A9 is a known fructose transporter, and we now show that it has strong uric acid transport activity in Xenopus laevis oocytes.
Collapse
Affiliation(s)
- Veronique Vitart
- MRC Human Genetics Unit, Western General Hospital, Edinburgh EH4 2XU, UK
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
180
|
Eraly SA, Vallon V, Rieg T, Gangoiti JA, Wikoff WR, Siuzdak G, Barshop BA, Nigam SK. Multiple organic anion transporters contribute to net renal excretion of uric acid. Physiol Genomics 2008; 33:180-92. [PMID: 18270321 DOI: 10.1152/physiolgenomics.00207.2007] [Citation(s) in RCA: 172] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Excretion of uric acid, a compound of considerable medical importance, is largely determined by the balance between renal secretion and reabsorption. The latter process has been suggested to be principally mediated by urate transporter 1 (URAT1; slc22a12), but the role of various putative urate transporters has been much debated. We have characterized urate handling in mice null for RST, the murine ortholog of URAT1, as well as in those null for the related organic anion transporters Oat1 and Oat3. Expression of mRNA of other putative urate transporters (UAT, MRP2, MRP4, Oatv1) was unaffected in the knockouts, as were general indexes of renal function (glomerular filtration rate, fractional excretion of fluid and electrolytes). While mass spectrometric analyses of urine and plasma revealed significantly diminished renal reabsorption of urate in RST-null mice, the bulk of reabsorption, surprisingly, was preserved. Oat1- and Oat3-null mice manifested decreased secretion rather than reabsorption, indicating that these related transporters transport urate in the "opposite" direction to RST. Moreover, metabolomic analyses revealed significant alteration in the concentration of several molecules in the plasma and urine of RST knockouts, some of which may represent additional substrates of RST. The results suggest that RST, Oat1, and Oat3 each contribute to urate handling, but, at least in mice, the bulk of reabsorption is mediated by a transporter(s) that remains to be identified. We discuss the data in the context of recent human genetic studies that suggest that the magnitude of the contribution of URAT1 to urate reabsorption might vary with ethnic background.
Collapse
Affiliation(s)
- Satish A Eraly
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | | | | | | | | | | | | | | |
Collapse
|
181
|
Identification and characterization of expressed sequence tags from the liver of rare minnow (Gobiocypris rarus). COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY D-GENOMICS & PROTEOMICS 2007; 2:356-62. [DOI: 10.1016/j.cbd.2007.09.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2007] [Revised: 09/10/2007] [Accepted: 09/10/2007] [Indexed: 11/19/2022]
|
182
|
Palmer BF, Naderi ASA. Metabolic complications associated with use of thiazide diuretics. ACTA ACUST UNITED AC 2007; 1:381-92. [DOI: 10.1016/j.jash.2007.07.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Revised: 07/21/2007] [Accepted: 07/24/2007] [Indexed: 10/22/2022]
|
183
|
Hagos Y, Bahn A, Vormfelde SV, Brockmöller J, Burckhardt G. Torasemide Transport by Organic Anion Transporters Contributes to Hyperuricemia. J Am Soc Nephrol 2007; 18:3101-9. [DOI: 10.1681/asn.2007010106] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
|
184
|
Sato M, Iwanaga T, Mamada H, Ogihara T, Yabuuchi H, Maeda T, Tamai I. Involvement of Uric Acid Transporters in Alteration of Serum Uric Acid Level by Angiotensin II Receptor Blockers. Pharm Res 2007; 25:639-46. [PMID: 17674156 DOI: 10.1007/s11095-007-9401-6] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2007] [Accepted: 06/28/2007] [Indexed: 12/20/2022]
Abstract
PURPOSE To examine the mechanisms of the alteration of serum uric acid level by angiotensin II receptor blockers (ARBs), the effects of ARBs on renal uric acid transporters, including OAT1, OAT3, OAT4, and MRP4, were evaluated. MATERIALS AND METHODS Uptakes of uric acid by OAT1-expressing Flp293 cells, by Xenopus oocytes expressing OAT3 or OAT4, and by membrane vesicles from Sf9 cells expressing MRP4 were evaluated in the presence or absence of ARBs. RESULTS All ARBs inhibited uptake of uric acid or estrone-3-sulfate by OAT1, OAT3 and OAT4 in concentration dependent manners. Among them, the IC50 values of valsartan, olmesartan and pratosartan for OAT3 were comparable to clinically observed unbound maximum plasma concentration of ARBs. Candesartan, losartan, and telmisartan inhibited ATP-dependent uptake of uric acid by MRP4 at 10 microM. The IC50 value of losartan for MRP4 was comparable to the estimated kidney tissue concentration of losartan. No ARBs showed trans-stimulatory effects on the uptake of estrone-3-sulfate by OAT4. CONCLUSION Valsartan, olmesartan, and pratosartan could inhibit the OAT3-mediated uric acid secretion in clinical situations. Furthermore losartan could inhibit ATP-dependent uric acid secretion by MRP4. These effects may explain partially the alteration of serum uric acid level by ARBs.
Collapse
Affiliation(s)
- Masanobu Sato
- Department of Membrane Transport and Pharmacokinetics, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamasaki, Noda, Chiba 278-8510, Japan
| | | | | | | | | | | | | |
Collapse
|
185
|
Rizwan AN, Krick W, Burckhardt G. The chloride dependence of the human organic anion transporter 1 (hOAT1) is blunted by mutation of a single amino acid. J Biol Chem 2007; 282:13402-9. [PMID: 17353191 DOI: 10.1074/jbc.m609849200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Organic anion transporter 1 (OAT1) is key for the secretion of organic anions in renal proximal tubules. These organic anions comprise endogenous as well as exogenous compounds including frequently used drugs of various chemical structures. The molecular basis for the polyspecificity of OAT1 is not known. Here we mutated a conserved positively charged arginine residue (Arg(466)) in the 11(th) transmembrane helix of human OAT1. The replacement by the positively charged lysine (R466K) did not impair expression of hOAT1 at the plasma membrane of Xenopus laevis oocytes but decreased the transport of p-aminohippurate (PAH) considerably. Extracellular glutarate inhibited and intracellular glutarate trans-stimulated wild type and mutated OAT1, suggesting for the mutant R466K an unimpaired interaction with dicarboxylates. However, when Arg(466) was replaced by the negatively charged aspartate (R466D), glutarate no longer interacted with the mutant. PAH uptake by wild type hOAT1 was stimulated in the presence of chloride, whereas the R466K mutant was chloride-insensitive. Likewise, the uptake of labeled glutarate or ochratoxin A was chloride-dependent in the wild type but not in R466K. Kinetic experiments revealed that chloride did not alter the apparent K(m) for PAH but influenced V(max) in wild type OAT1-expressing oocytes. In R466K mutants the apparent K(m) for PAH was similar to that of the wild type, but V(max) was not changed by chloride removal. We conclude that Arg(466) influences the binding of glutarate, but not interaction with PAH, and interacts with chloride, which is a major determinant in substrate translocation.
Collapse
Affiliation(s)
- Ahsan N Rizwan
- Abteilung Vegetative Physiologie und Pathophysiologie, Zentrum Physiologie und Pathophysiologie, Georg-August-Universität Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
| | | | | |
Collapse
|
186
|
Rizwan AN, Burckhardt G. Organic anion transporters of the SLC22 family: biopharmaceutical, physiological, and pathological roles. Pharm Res 2007; 24:450-70. [PMID: 17245646 DOI: 10.1007/s11095-006-9181-4] [Citation(s) in RCA: 195] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2006] [Accepted: 10/19/2006] [Indexed: 02/08/2023]
Abstract
The human organic anion transporters OAT1, OAT2, OAT3, OAT4 and URAT1 belong to a family of poly-specific transporters mainly located in kidneys. Selected OATs occur also in liver, placenta, and brain. OATs interact with endogenous metabolic end products such as urate and acidic neutrotransmitter metabolites, as well as with a multitude of widely used drugs, including antibiotics, antihypertensives, antivirals, anti-inflammatory drugs, diuretics and uricosurics. Thereby, OATs play an important role in renal drug elimination and have an impact on pharmacokinetics. In this review we focus on the interaction of human OATs with drugs. We report the affinities of human OATs for drug classes and compare the putative importance of individual OATs for renal drug excretion. The role of OATs as sites of drug-drug interaction and mediators cell toxicity, their gender-dependent regulation in health and diseased states, and the possible impact of single nucleotide polymorphisms are also dealt with.
Collapse
Affiliation(s)
- Ahsan N Rizwan
- Abteilung Vegetative Physiologie und Pathophysiologie, Bereich Humanmedizin, Georg-August-Universität Göttingen, Humboldtallee 23, 37073, Göttingen, Germany
| | | |
Collapse
|