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BACKGROUND: Urate transporters such as GLUT9, URAT1, NPT1 and ABCG2 are directly involved in the regulation of human serum uric acid levels. The gene polymorphism of urate transporter is closely related to the occurrence and development of gout. Therefore, the targeted therapy of urate transporter is a new way to treat gout. OBJECTIVE: To summarize the research progress of polymorphism expression of urate transporter in gout and its correlation with clinical drugs in recent years, therefore providing literature and theoretical basis for further exploration of personalized treatment of gout and hyperuricemia. METHODS: The first author searched CNKI, WanFang database and PubMed database. The key words were “Gout, Urate transporter, Hyperuricemia, Polymorphism, GWAS, Therapy” in Chinese and English, respectively. Totally 131 literatures were retrieved. According to the inclusion and exclusion criteria, 78 articles regarding the genetic polymorphism of urate transporter in gout and the correlation between the mechanism of action of gout drugs and urate transporter were screened out and summarized. RESULTS AND CONCLUSION: A large number of studies have shown that urate transporter polymorphism is closely related to uric acid homeostasis, with GLUT9, URAT1, NPT1 and ABCG2 being the most important. These proteins are differentially expressed in different populations and are closely related to the reaction mechanism of gout drugs. In the future diagnosis and treatment, the results of these studies can help assess the need for treatment in patients with hyperuricemia, and help patients with gout formulate personalized and effective treatment plans. It may be a feasible solution to treat hyperuricemia by activating BCRP to enhance the clearance of uric acid in the intestine.
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Objective:Study on the mechanism of Tongfengning in promoting uric acid excretion from the perspective of urate transporter and mRNA in renal of hyperuricemia （HUA） model rats. Method:The 80 sprague-dawley rats were randomly divided into two groups， the blank group with 20 rats and the model group with 60 rats. Rats in model group were established as hyperuricemia （HUA） models by intraperitoneal injection of oxonic acid potassium salt （OAPS） and intragastric administration ethambutol hydrochloride （EMB） once a day for 21 days. After successful modeling， rats in the model group were divided into the model group， Tongfengning group and benzbromarone group， with 20 rats per group. Tongfengning solution （15.3 g·kg-1·d-1） was administered to the Tongfengning group by gavage feeding. Rats in benzbromarone group were administered 5.2 mg·kg-1·d-1 benzbromarone suspension， whereas those in the blank group and the model group were administered the equivalent amount of normal saline for 21 days. On days 14th and 21st following intervention， urine， blood， and kidney were collected from rats， serum uric acid （SUA） and urinary uric acid （UUA） levels， blood urea nitrogenand（BUN） and creatinine（CRE） levels and the expression of urate transporter proteins and their mRNAs of all rats were detected by enzyme-colorimetric method， urease method， sarcosine oxidase method， Western blot and Real-time quantitative PCR（Real-time PCR）， respectively. Result:On days 14th and 21th following intervention， compared with blank group， SUA， CRE and BUN levels， and urate transporter 1（URAT1），glucose transporter 9（GLUT9） expression increased（P<0.05，P<0.01）， whereas UUA level， and adenosine triphosphate-binding cassette transporter protein G2（ABCG2）， organic anion 1（OAT1）， organic anion 3（OAT3） expression decreased in the model group（P<0.05，P<0.01）. Compared with model group， SUA， CRE and BUN levels， and URAT1， GLUT9 expression decreased in Tongfengning group and the benzbromarone group（P<0.05）， whereas UUA level， and ABCG2， OAT1， OAT3 expression increased（P<0.05）. Creatinine and BUN levels decreased in the Tongfengning group（P<0.05，P<0.01）， with the trend much better than the benzbromarone group（P<0.05）. On day 21st， except for the BUN level did not change much compared with day 14th， all the rest indicators got improved obviously. Conclusion:Intraperitoneal injection of OAPS and intragastric administration of EMB can cause HUA models with renal dysfunction. Tongfengning reduced URAT1， GLUT9 mRNA and protein expression， and upregulated ABCG2， OAT1， OAT3 mRNA and protein expression in the rat kidney， which may be one of the mechanisms of promoting uric acid excretion. Tongfengning has a certain protective effect on renal function.
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Objective To study the effects of Chinese herb ingredients with different properties on transporters (URAT1 and OAT4) involved in renal urate reabsorption and serum uric acid level in acute hyperuricemia mice. Methods The OAT4, URAT1- overexpressed monoclonal cell line (MDCK-hOAT4, HEK293-hURAT1) was constructed. The inhibition effect and the half maximal inhibitory concentration (IC50) of different ingredients to transport activity of OAT4 and URAT1 mediating 14C-uric acid were determined. The effects of protocatechuic, liquiritigenin and isoliquiritigenin on serum uric acid levels in acute hyperuricemia mice were studied by the acute hyperuricemia mice induced by potassium oxonate and xanthine. Results The results indicated that nobiletin,liquiritigenin, isoliquiritigenin, licochalcone A with bitter flavor showed strong inhibition to OAT4. The IC50 of nobiletin, liquiritigenin, isoliquiritigenin, and licochalcone A on OAT4 were 0.556 μmol/L, 18.40 μmol/L, 6.831 μmol/L, and 6.825 μmol/L, respectively. Protocatechuic acid and liquiritigenin showed strong inhibition to URAT1 with IC50 of 7.709 μmol/L and 14.54 μmol/L, respectively. Liquiritigenin can significantly reduce the level of serum uric acid of acute hyperuricemia mice, increase the excretion of uric acid, and reduce the level of serum creatinine and blood urea nitrogen. Conclusion Nobiletin, liquiritigenin, isoliquiritigenin and licochalcone A can inhibit the transport activity of OAT4, while protocatechuic acid and liquiritigenin can inhibit the transport activity of URAT1. Liquiritigenin can significantly reduce the level of serum uric acid in acute hyperuricemia mice and protect kidney, the mechanism of which may be associated with the decreasing reabsorption of uric acid by inhibiting the activity of URAT1 and OAT4.
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Objective: Study on the mechanism of Tongfengning in reducing serum uric acid from the perspective of renal urate transporter. Method: The human renal tubular epithelial cells(HK-2)was randomly divided into normal group, model group, Tongfengning low, medium and high dose group (7.65,15.3,30.6 g·kg-1) and benzbromarone group (50 μmo1·L-1),different culture media were given for intervention.HK-2 and cell supernatant were collected after 24 h of intervention. The expressions of urate transporter 1 (URAT1), glucose transporter 9 (GLUT9), organic anion transporter 1(OAT1), organic anion transporter 3(OAT3), and ATP-binding cassette superfamily G member 2 (ABCG2) protein and mRNA were detected in HK-2 of all groups by Western blot and Real-time PCR. Result: Compared with normal group, the expression of URAT1, GLUT9 protein and mRNA was significantly increased(PPPPPConclusion: Tongfengning can regulate the reabsorption and secretion of uric acid in renal tubules, promote the excretion of uric acid in kidney and reduce the level of serum uric acid by down-regulating the expression of URAT1, GLUT9 protein and mRNA in HK-2 and up-regulating the expression of ABCG2 protein and mRNA. It is suggested that the regulation of renal uric acid transporter protein may be one of the specific mechanisms of Tongfengning to reduce serum uric acid by promoting dampness and turbid removal. OAT1, OAT3 protein and mRNA were not expressed in HK-2 cultured in vitro.
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Objective: To observe the effect of phlegm and blood stasis on the expressions of sirtuin 3(SIRT3)protein and urate transporter 1(URAT1) mRNA in skeletal muscle of diabetic rats with gout. Method: The 40 healthy rats, excepting the normal group, the remaining groups were fed with high-fat diet combined with low-dose streptozotocin solution (40 mg·kg-1) once a day, with blood glucose "16.7 mmol·L-1" as the criterion for the diabetes model. After 4 days, the 5% sodium urate solution was injected into the joint cavity once to induce the gout model. After the successful modeling, the Biling group (10 g·kg-1), the indomethacin group (5 mg·kg-1) and the pioglitazone group (10 mg·kg-1) continued to be administered for 21 days. The normal group and the model group were given the same amount of normal saline. The expression of SIRT3 protein in skeletal muscle tissue was determined by Western blot, URAT1 mRNA expression in bone tissue was detected by quantitative real-time fluorescence polymerase chain reaction(Real-time PCR),and blood was collected to measure blood glucose (GLU), blood uric acid (UA) and C-reactive protein (CRP). Result: Compared with the normal group, GLU, UA and CRP in the model group were significantly increased (PPPPPPPPConclusion: Biling Qutong prescription with effects in purging turbidity, detoxifying and dredging collaterals can significantly reduce the content of serum inflammatory factor CRP, significantly increase the protein expression of SIRT3 in skeletal muscle tissue of model rats, lower the content of URAT1 mRNA, reduce the blood glucose and blood uric acid levels in diabetic gout rats, and protect joints.
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A mangiferin aglycon derivative J99745 has been identified as a potent xanthine oxidase (XOD) inhibitor by previous study. This study aimed to evaluate the hypouricemic effects of J99745 in experimental hyperuricemia mice, and explore the underlying mechanisms. Mice were orally administered 600 mg/kg xanthine once daily for 7 days and intraperitoneally injected 250 mg/kg oxonic acid on the 7th day to induce hyperuricemia. Meanwhile, J99745 (3, 10, and 30 mg/kg), allopurinol (20 mg/kg) or benzbromarone (20 mg/kg) were orally administered to mice for 7 days. On the 7th day, uric acid and creatinine in serum and urine, blood urea nitrogen (BUN), malondialdehyde (MDA) content and XOD activities in serum and liver were determined. Morphological changes in kidney were observed using hematoxylin and eosin (H&E) staining. Hepatic XOD, renal urate transporter 1 (URAT1), glucose transporter type 9 (GLUT9), organic anion transporter 1 (OAT1) and ATP-binding cassette transporter G2 (ABCG2) were detected by Western blot and real time polymerase chain reaction (PCR). The results showed that J99745 at doses of 10 and 30 mg/kg significantly reduced serum urate, and enhanced fractional excretion of uric acid (FEUA). H&E staining confirmed that J99745 provided greater nephroprotective effects than allopurinol and benzbromarone. Moreover, serum and hepatic XOD activities and renal URAT1 expression declined in J99745-treated hyperuricemia mice. In consistence with the ability to inhibit XOD, J99745 lowered serum MDA content in hyperuricemia mice. Our results suggest that J99745 exerts urate-lowering effect by inhibiting XOD activity and URAT1 expression, thus representing a promising candidate as an anti-hyperuricemia agent.
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Hyperuricemia is a heterogeneous group of diseases caused by disorders of purine metabolism and /or excretion of uric acid reduction .Chinese medicine treatment of hyperurice-mia has gradually attracted attention , and made significant pro-gress.In recent years a large number of experimental studies have shown that flavonoids , saponins , alkaloids and other active components of traditional Chinese medicine can reduce uric acid by inhibiting the activity of key enzymes in purine metabolism ,or by increasing the excretion of uric acid through regulating the expression of uric acid transporters , thereby playing an important role in reducing uric acid .Based on the pathogenesis of hyperu-ricemia, the mechanism of active components of traditional Chi-nese medicine for reducing uric acid is summarized , and recent research reports are reviewed .
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Objective To explore the protective effect and underlying mechanism of telmisartan on hyperuricemic nephropathy.Methods (1)High level of uric acid (600 μmol/L) and telmisartan in different concentrations (10nmol/L,100 nmol/L,1000 nmol/L,10000 nmol/L) were added to renal tubule epithelial cells and cultured for 48 h,the expression of UAT,TGF-β1 and α-SMA were detected by Real-time PCR,RT-PCR,Western blotting or cell immunofluorescence.(2) Wister rats were randomly divided into normal control group(Con),high uric acid group (HU),and telmisartan treatment group (Tel).Four weeks later,Scr,BUN and serum uric acid of the rats were detected.The expression of UAT in rat kidney was detected by Western blotting.Results (1)In vitro,compared to control group,high uric acid (600 μmol/L) inhibited the expression of UAT (P ＜ 0.01),and the inhibition could be alleviated by telmisartan; Telmisartan inhibited the upregulation of TGF-β1 and α-SMA induced by high uric acid(all P ＜ 0.05); (2)In vivo,compared to high uric acid group rats,telmisartan group rats had significantly reduced serum uric acid levels (189.9 μmol/L vs 204.5 μmol/L,P＜0.05),upregulated UAT and downregulated TGF-β1 expression in rat kidney (all P＜ 0.05).Conclusion Telmisartan significantly inhibits the upregulation of TGF-β1 and α-SMA induced by uricemia,which may prevent kidney from fibrosis.The protect effect of telmisartan may be related to the upregulation of UAT.
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Human proximal tubule epithelial cell line,HK-2 cells,were cultured with various concentrations of insulin for 48 h.Human urate transporter (hUAT) mRNA was detected by realtime quantitative PCR.hUAT mRNA levels were down-regulated by insulin (5,25,125,500 μIU/ml)in a dose-dependent manner (relative expression median were 0.95,0.40,0.24,and 0.23).In vitro,the expression of hUAT mRNA in HK-2 cells is associated with the concentration of insulin.
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Objective We reported previously that single nucleotide polymorphisms SNP) + 11G ＞ A in intron 3 of the human urate transporter 1 (hURAT1) gene are associated with hyperuncaemia in Han Chinese.The aim of the present study was to evaluate the effect of the variants on hURAT1 function.Methods The wild-type,mutant-type hURAT1 and exon 5-null hURAT1 were constructed,and respectively microinjected into the zebrafish embryo yolks.The subcellular localization of different genotypes of hURAT1 was detected by confocal laser scanning microscope.Results Compared with wild type,the mutant recombinant plasmid transcribed two types of mRNA spliceosome,the wild type and the exon 5-null type.The hURAT1 wild type protein was prominent localized on cell membrane,while the mutant type and exon 5-null hURAT1 proteins were distributed uniform in the cytoplasm but not on the cell membrane.Conclusion The hURAT1 variant + 11 G ＞ A resulted in an alternative splicing of hURAT1 mRNA-exon 5-null type.Its protein product exhibited a different subcellular localization compared with that of wild type.
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TP-binding cassette superrfamily G member 2(ABCG2), a transporter protein localizing in cell membrane and expressing in renal tubular epithelial cell brush border side, has the function of transport uric acid. In recent years, single nucleotide polymorphism (SNP) analysis has confirmed that ABCG2 is one of the most important uric acid transporters, whose dysfunction would hinder the kidney and intestinal excretion of uric acid, then increase serum uric acid and causes gout. The review summarizes the relationship between ABCG2 transporter protein and uric acid metabolism, and the SNP affecting on uric acid metabolism.
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ObjectiveTo analyze the association of human urate transporter 1 ( hURAT1 ) gene promoter single-nucleotide polymorphisms(SNPs) with primary hyperuricemia ( HUA ) in Chinese Han people.MethodsA total of 215 patients with HUA and 323 healthy subjects were chosen to be investigated of SNP of hURAT1 promoter by PCR and sequencing.ResultsFive SNPs were identified,including-454A/T,-434T/C,-382C/T,-87C/T,and + 118G/A.Pairwise linkage disequilibrium analysis displayed a high linkage disequilibrium between the five SNPs ( r2 =0.99).In HUA group,the heterozygous genotypos ( AT,CT,CT,CT,AG ) frequencies were significantly lower than those in control group ( P＜0.05 ).Logistic regression analysis showed that the heterozygosis genotypes ( AT,CT,CT,CT,AG) were protective factors of HUA ( OR 0.68-0.75 ).The minor allele ( T,C,T,T,A ) frequencies for both SNPs were significantly different between two groups ( P =0.022,P =0.038 ).ConclusionThese findings indicate that -454A/T,-434T/C,-382C/T,-87C/T,and + 118G/A SNPs of hURAT1 gene promoter area are associated with HUA in Chinese Han population.
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Hyperuricemia is a kind of metabolic disease caused by the disorder of purine metabolism, which eads to the ncrease of uric acid production and(or) the decrease of uric acid excretion. It not only s the important biochemical basis of gout, but also has close relationship with hypertension, hyperlipidemia, atherosclerosis, obesity and nsulin resistance. So studies on the pathogenesis and pharmacotherapy of hyperuricemia have become the focus of attention. This review summaries the pathogenesis of hyperuricemia and the research progress in pharmacotherapy from two aspects: inhihition to the generation and promotion to the excretion of uric acid.
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Objective To observe whether high-level insulin increases serum uric acid level and rosiglitazone improves hyperuricemia, and to explore the mechanism. Methods OLETF rats with spontaneous type 2 diabetes complicated with metabolic syndrome and normal control LETO rats were randomly divided into three groups (n=20 each). The animals were fed with standard chow diet in control group, high-purine diet and adenine administered intragastrically in experimental group, and rosiglitazone in interventional group. Body weight, serum levels of uric acid, insulin, triglyceride ( TG ) , and total cholesterol ( TC ) were measured after 3 weeks. Urate transporter 1 ( URAT1 ) and uric acid transporter (UAT) mRNA expressions in renal cortex were examined. HK-2 cells were incubated with various concentrations of insulin for 24 hours. UAT mRNA expression in HK-2 cells was examined. Results ( 1 ) In control group, the insulin level of OLETF rats was significantly higher than that of LETO rats ( P<0. 05 ), and there was no significant difference in serum uric acid level between OLETF and LETO rats. (2)In experimental groups, the insulin level in OLETF rats was significantly higher than that in LETO rats [(61.83±12.13 vs 36.73±12.73 )μIU/ml ,P<0. 05], and the incidence of hyperuricemia (76.92% vs 36.13%,P<0.01 ) and serum uric acid level[( 327.75 ±45.73 vs 264.40±36.32 ) μmol/L, P<0. 01]in OLETF rats were significantly higher than those in LETO rats. (3) Insulin[(41.3± 10.2 vs 61.8±12. 1 )μIU/ml,P<0. 05]and uric acid[( 198.0±45.4 vs 236.9±29.30 ) μmol/L, P<0. 05]levels in OLETF rats in interventional group were significantly lower than those of OLETF rats in experimental group, meanwhile the amount of urinary uric acid excretion was significantly increased[(5 644±371 vs 4 692±278 ) μ mol/L, P<0. 05]. (4) There was no significant difference in insulin level and the expressions of URAT1 and UAT mRNA in renal cortex between OLETF rats in control group and experimental group. URAT1 mRNA expression of OLETF rats in interventional group was significantly decreased, while UAT mRNA expression was significantly increased. (5)With the increase of insulinconcentration in culture medium, the expression of UAT mRNA expression in HK-2 cells was gradually decreased. Conclusions Rosiglitazone may alleviate hyperinsulinemia-induced hyperuricemia via regulating UAT and URAT1 mRNA expression.
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Idiopathic renal hypouricemia is a disorder characterized by impaired urate handling in the renal tubules. This disease usually produces no symptoms, but hematuria, uric acid nephrolithiasis or acute renal failure may develop. A defect in the SLC22A12 gene, which encodes the human urate transporter, is the known major cause of this disorder. We describe a 10-month-old boy with idiopathic renal hypouricemia. He was diagnosed with transient pseudohypoaldosteronism at admission, but hypouricemia was accidentally found through follow-up study. By gene analysis, his diagnosis was confirmed to idiopathic renal hypouricemia. In addition, we report a mutation in the human urate transporter 1 (hURAT1) gene identified in his family.