Overview of organic anion transporters and organic anion transporter polypeptides and their roles in the liver

Organic anion transporters(OATs)and organic anion transporter polypeptides(OATPs)are classified within two SLC superfamilies,namely,the SLC22A superfamily and the SLCO superfamily(formerly the SLC21A family),respectively.They are expressed in many tissues,such as the liver and kidney,and mediate the absorption and excretion of many endogenous and exogenous substances,including various drugs.Most are composed of 12 transmembrane polypeptide chains with the C-terminus and the N-terminus located in the cell cytoplasm.OATs and OATPs are abundantly expressed in the liver,where they mainly promote the uptake of various endogenous substrates such as bile acids and various exogenous drugs such as antifibrotic and anticancer drugs.However,differences in the locations of glycosylation sites,phosphorylation sites,and amino acids in the OAT and OATP structures lead to different substrates being transported to the liver,which ultimately results in their different roles in the liver.To date,few articles have addressed these aspects of OAT and OATP structures,and we study further the similarities and differences in their structures,tissue distribution,substrates,and roles in liver diseases.

Expression and function of renal and hepatic organic anion transporters in extrahepatic cholestasis

Obstructive jaundice occurs in patients suffering from cholelithiasis and from neoplasms affecting the pancreas and the common bile duct.The absorption,distribution and elimination of drugs are impaired during this pathology.Prolonged cholestasis may alter both liver and kidney function.Lactam antibiotics,diuretics,non-steroidal anti-inflammatory drugs,several antiviral drugs as well as endogenous compounds are classified as organic anions.The hepatic and renal organic anion transport pathways play a key role in the pharmacokinetics of these compounds.It has been demonstrated that acute extrahepatic cholestasis is associated with increased renal elimination of organic anions.The present work describes the molecular mechanisms involved in the regulation of the expression and function of the renal and hepatic organic anion transporters in extrahepatic cholestasis,such as multidrug resistanceassociated protein 2,organic anion transporting polypeptide 1,organic anion transporter 3,bilitranslocase,bromosulfophthalein/bilirubin binding protein,organic anion transporter 1 and sodium dependent bile salt transporter.The modulation in the expression of renal organic anion transporters constitutes a compensatory mechanism to overcome the hepatic dysfunction in the elimination of organic anions.

Organic anion transporters also mediate the drug–drug interaction between imipenem and cilastatin

This study aimed to clarify that organic anion transporters(OATs)mediate the drug–drug interaction(DDI)between imipenem and cilastatin.After co-administration with imipenem,the plasma concentrations and the plasma concentration-time curve(AUC)of cilastatin were significantly increased,while renal clearance and cumulative urinary excretion of cilastatin were decreased.At the same time,imipenem significantly inhibited the uptake of cilastatin in rat kidney slices and in human OAT1(hOAT1)-HEK293 and human OAT3(hOAT3)-HEK293 cells.Probenecid,p-aminohippurate,and benzylpenicillin inhibited the uptake of imipenem and cilastatin in rat kidney slices and in hOAT1-and hOAT3-HEK 293 cells,respectively.The uptakes of imipenem and cilastatin in hOAT1-and hOAT3-HEK 293 cells were significantly higher than that in mock-HEK-293 cells.Moreover,the K m values of cilastatin were increased in the presence of imipenem with unchanged V max,indicating that imipenem inhibited the uptake of cilastatin in a competitive manner.When imipenem and cilastatin were co-administered,the level of imipenem was higher compared with imipenem alone both in vivo and in vitro.But,cilastatin significantly inhibited the uptake of imipenem when dehydropeptidase-1(DPEP1)was silenced by RNAi technology in hOAT1-and hOAT3-HEK 293 cells.In conclusion,imipenem and cilastatin are the substrates of OAT1 and OAT3.OAT1 and OAT3 mediate the DDI between imipenem and cilastatin.Meanwhile,cilastatin also reduces the hydrolysis of imipenem by inhibiting the uptake of imipenem mediated by OAT1 and OAT3 in the kidney as a complement.

Piperacillin enhances the inhibitory effect of tazobactam on β-lactamase through inhibition of organic anion transporter 1/3 in rats

To assess the mechanism of the pharmacokinetic interaction between piperacillin and tazobactam,renal excretion and pharmacokinetic studies of piperacillin/tazobactam were investigated in normal and bacteremia rats.A bacteremia model was established to investigate the pharmacokinetic properties of piperacillin and tazobactam under different conditions.Renal slices were taken to examine the uptake of piperacillin and tazobactam.Pharmacokinetic studies ofβ-lactamase in rats were performed to study the contribution of rOat1/3 to the inhibition of tazobactam onβ-lactamase.The AUC(from 2.93±0.58 to 6.52±1.44 mg·min/ml)and the plasma clearance(CL P)(from 2.41±1.20 to 0.961±0.212 ml/min/kg)of tazobactam were both altered after the intravenous coadministration of piperacillin and tazobactam in the bacteremia rats.The renal clearance(CL R)of tazobactam decreased from 1.30±0.50 to 0.361±0.043 ml/min/kg.In summary,there was a beneficial interaction between piperacillin and tazobactam mediated by rOat1 and rOat3.Piperacillin enhances the inhibitory effect of tazobactam onβ-lactamase through the inhibition of rOat1 and rOat3 in rats.The contribution rate of rOat1/3 for the synergistic effect was 20%when the two drugs were coadministered.

Effects of Cangfudaotan Tang on Expression of Organic Anion Transporting Polypeptide (oatp2b1) in Liver and Kidney Tissues of Rats with Phlegm Dampness Type Polycystic Ovary Syndrome (PCOS)

Objective: To explore the effect of Cangfudaotan Tang on phlegm dampness type of PCOS and the role of oatp2b1 in transportation and transformation of phlegm dampness. Methods: 36 SD female rats were randomly divided into three groups: blank control group, model group and Cangfudaotan Tang group, 12 cases in each one. After PCOS rat models were made, rats of Cangfudaotan Tang group were treated with Cangfudaotan Tang (1.42 g/kg/d) by intragastric administration for 14 days;blank control and model group were given with isodose saline. The expression of oatp2b1 mRNA/Protein in liver and kidney tissues was measured and the level of testosterone (T), follicle stimulating hormone(FSH), estradiol (E2), luteinizing hormone(LH), Serum total cholesterol (TG), Triacylglycerols (TC), high density lipoprotein cholesterol (HDL-C) and low density lipoprotein cholesterol (LDL-C) were detected at the same time. Results: Compared with blank control group, the expression of oatp2b1 mRNA and the level of TC, TG, LDL, LH, FSH, T in model group were significantly increased (P < 0. 05), while the level of HDL was significantly decreased (P < 0. 05);compared with model group, the expression of oatp2b1 mRNA and the level of TC, TG, LDL in Cangfudaotan Tang group were significantly lowered (P < 0.05);the level of HDL was significantly higher;the oatp2b1 protein in kidney and liver tissues had different degrees of expression, while there was no statistical significance among the three groups. Conclusions: Oatp2b1 might be one of the material bases participating in transportation and transformation of phlegmy dampness. The mechanism of Cangfudaotan Tang treating phlegm dampness type of PCOS may be achieved by regulating the expression of oatp2b1.

Ionic covalent organic frameworks with tailored anionic redox chemistry and selective ion transport for high-performance Na-ion cathodes

Employing cathode materials with multiple redox couples and electrolytes with efficient cation transport kinetics are two effective approaches to improving the electrochemical performance of batteries.In this work,for the first time,we present a design strategy of simultaneously realizing reversible cationic and anionic redox chemistries as well as selective anion/cation transport in the viologen-based COFs(BAVCOF:X,coordinated anions of X=Cl^(-),Br^(-),I^(-),and ClO_(4)^(-))for high-performance Na-ion cathodes.Besides the cationic redox of viologen segments,the different redox activities of anions effectively tune the total capacities of the COFs.Meanwhile,electrochemical analysis and ab-initial molecular dynamics(AIMD)calculation illustrate that the anion/cation transport kinetics of electrolytes caged in the COFs'channels can be selectively tuned by the coordinated anions.As a result,combining high-potential Br-/Br_(2)redox couple,cationic redox of viologen segments,and enhanced Na+transport kinetics,the BAV-COF:Brdemonstrates stable performance with energy densities of 358.7 and 145.2 Wh kg^(-1)at power densities of 116.5 and 2124.1 W kg^(-1),respectively.This study offers new insight into the fabrication of organic cathodes with anionic redox and the advantages of COFs electrode materials in anion/cation transport selectivity for energy storage applications.

Influence of organic anion transporting potypeptide(SLCO1B1 and SLCO1B3)genetic polymorphisms on mycophenolic acid in Chinese kidney transplantation patients

Objective To analyze the relationship between genetic polymorphisms of organic anion transporting polypeptide ( SLCO1B1 and SLCO1B3) and mycophenolic acid ( MPA) pharmacokinetics in Chinese kidney transplant recipients. Methods Gene mutations ( SLCO1B3 T334G,SLCO1B1 A338G) were detected in 68 recipi-

PGE_(2)通过EP4/PKA信号通路调控滑膜细胞OAT1的表达及CP-25的作用

目的明确前列腺素E2(prostaglandin E2,PGE_(2))对滑膜细胞有机阴离子转运体1(organic anion transporter 1,OAT1)膜表达的调控机制及芍药苷-6'-O-苯磺酸酯(CP-25)的作用。方法免疫荧光法检测不同浓度CP-25对PGE_(2)处理后滑膜细胞OAT1和前列腺素E受体4(prostaglandin E receptor 4,EP4)表达的影响;使用EP4激动剂(TCS2510)与拮抗剂(GW627368X),探究EP4在OAT1调节中的作用;使用CP-25和蛋白激酶A(protein kinase A,PKA)抑制剂H-89,探究CP-25和PKA对滑膜细胞OAT1表达的影响。结果PGE_(2)在0~10 min内明显下调EP4与OAT1的膜表达,20~60 min后明显上调(P<0.05);CP-25明显上调PGE_(2)处理后细胞膜OAT1和EP4的表达(P<0.05);EP4激动剂TCS2510明显上调细胞膜OAT1的表达(P<0.01);CP-25上调PGE_(2)处理的细胞中OAT1的表达,GW627368X和H-89均能下调PGE_(2)和CP-25处理的滑膜细胞中OAT1的表达(P<0.01)。结论PGE_(2)介导的EP4/PKA信号通路可以调控OAT1在滑膜细胞膜上的表达,CP-25可以通过活化EP4/PKA信号通路明显上调滑膜细胞中OAT1的膜表达。

Renal elimination of organic anions in cholestasis

The disposition of most drugs is highly dependent on specialized transporters. OAT1 and OAT3 are two organic anion transporters expressed in the basolateral membrane of renal proximal tubule cells, identified as contributors to xenobiotic and endogenous organic anion secretion. It is well known that cholestasis may cause renal damage. Impairment of kidney function produces modifications in the renal elimination of drugs. Recent studies have demonstrated that the renal abundance of OAT1 and OAT3 plays an important role in the renal elimination of organic anions in the presence of extrahepatic cholestasis. Time elapsed after obstructive cholestasis has an important impact on the regulation of both types of organic anion transporters. The renal expression of OAT1 and OAT3 should be taken into account in order to improve pharmacotherapeutic efficacy and to prevent drug toxicity during the onset of this hepatic disease.

Expression of renal Oat5 and NaDC1 transporters in rats with acute biliary obstruction

AIM: To examine renal expression of organic anion transporter 5(Oat5) and sodium-dicarboxylate cotransporter 1(Na DC1), and excretion of citrate in rats with acute extrahepatic cholestasis.METHODS: Obstructive jaundice was induced in rats by double ligation and division of the common bile duct(BDL group). Controls underwent sham operation that consisted of exposure, but not ligation, of the common bile duct(Sham group). Studies were performed 21 h after surgery. During this period, animals were maintained in metabolic cages in order to collect urine. The urinary volume was determined by gravimetry. The day of the experiment, blood samples were withdrawn and used to measure total and direct bilirubin as indicative parameters of hepatic function. Serum and urine samples were used for biochemical determinations. Immunoblotting for Oat5 and Na DC1 were performed in renal homogenates and brush border membranes from Sham and BDL rats. Immunohistochemistry studies were performed in kidneys from both experimental groups. Total RNA was extracted from rat renal tissue in order to perform reverse transcription polymerase chain reaction. Another set of experimental animals were used toevaluate medullar renal blood flow(m RBF) using fluorescent microspheres.RESULTS: Total and direct bilirubin levels were significantly higher in BDL animals, attesting to the adequacy of biliary obstruction. An important increase in m RBF was determined in BDL group(Sham: 0.53 ± 0.12 m L/min per 100 g body weight vs BDL: 1.58 ± 0.24 m L/min per 100 g body weight, P < 0.05). An increase in the urinary volume was observed in BDL animals. An important decrease in urinary levels of citrate was seen in BDL group. Besides, a decrease in urinary citrate excretion(Sham: 0.53 ± 0.11 g/g creatinine vs BDL: 0.07 ± 0.02 g/g creatinine, P < 0.05) and an increase in urinary excretion of H+(Sham: 0.082 ± 0.03 μmol/g creatinine vs BDL: 0.21 ± 0.04 μmol/g creatinine, P < 0.05) were observed in BDL animals. We found upregulations of both proteins Oat5 and Na DC1 in brush border membranes where they are functional. Immunohistochemistry technique corroborated these results for both proteins. No modifications were observed in Oat5 m RNA and in Na DC1 m RNA levels in kidney from BDL group as compared with Sham ones.CONCLUSION: Citrate excretion is decreased in BDL rats, at least in part, because of the higher Na DC1 expression. Using the outward gradient of citrate generated by Na DC1, Oat5 can reabsorb/eliminate different organic anions of pathophysiological importance.

慢性肾衰竭大鼠OAT1的表达对骨代谢的影响

目的研究慢性肾衰竭时导致骨细胞有机阴离子转运蛋白(organic anion transporter,OAT)表达的变化,探讨OAT1表达对骨代谢的影响。方法将SD大鼠随机分为对照组(Control,n=6)和模型组(Model,n=6)。模型组采用“单肾切除+腺嘌呤灌胃法”建立大鼠慢性肾衰竭模型,通过血常规分析仪测定大鼠血清的红细胞(red blood cell,RBC)、血红蛋白(hemoglobin,Hb);通过全自动生化分析仪测定肌酐(creatinine,Cr)、尿素氮(urea nitrogen,BUN)、尿酸(uric acid,UA)、血钙(Ca^(2+))、血磷(P^(3+))等指标;对大鼠肾脏进行病理学检查;X线拍片检查大鼠胫骨标本;免疫组化检查骨组织OAT1表达。结果模型组大鼠的骨密度低于对照组;模型组大鼠钙磷代谢失调,并且骨组织结合OAT1值远低于对照组,差异具有统计学意义(P=0.0018)。结论慢性肾功衰竭影响OAT1在骨组织中的表达,导致钙磷代谢失调,从而加重肾性骨营养不良。

GABA transporter 1 transcriptional starting site exhibiting tissue specific difference

GABA transporter 1(GAT1) takes important roles in multiple physiological processes through the uptake and release of GABA, but the regulation of GAT1 gene expression in different tissues is rarely known. To address the question, first, 5’ Rapid amplification of cDNA end (RACE) was used to determine GAT1 transcriptional starting sites in neonatal mouse cerebral cortex and intestine, adult mouse brain and adult rat testis. The products of 5’RACE were confirmed by DNA sequencing. We found that the transcript of GAT1 in neonatal mouse cerebral cortex and adult mouse brain starts at the same site (inside of exon 1), while in mouse intestine, GAT1 starts transcription in intron 1, and in rat testis, the transcript of GAT1 has an additional untranslation exon to the 5’ direction.

Differential expression of cholangiocyte and ileal bile acid transporters following bile acid supplementation and depletion

AIM: We have previously demonstrated that cholangiocytes, the epithelial cells lining intrahepatic bile ducts,encode two functional bile acid transporters via alternative splicing of a single gene to facilitate bile acid vectorial transport. Cholangiocytes possess ASBT,an apical sodium-dependent bile acid transporter to take up bile acids,and t-ASBT,a basolateral alternatively spliced and truncated form of ASBT to efflux bile acids.Though hepatocyte and ileal bile acid transporters are in part regulated by the flux of bile acids, the effect of alterations in bile acid flux on the expression of t-ASBT in terminal ileocytes remains undear.Thus,we tested the hypothesis that expression of ASBT and t-ASBT in cholangiocytes and ileocytes was regulated by bile acid flux. METHODS: Expression of ASBT and t-ASBT message and protein in cholangiocytes and ileocytes isolated from pair- fed rats given control (C) and 1% taurocholate (TCA) or 5% cholestyramine (CY) enriched diets,were assessed by both quantitative RNase protection assays and quantitative immunoblotting.The data obtained from each of the control groups were pooled to reflect the changes observed following TCA and CY treatments with respect to the control diets. Cholangiocyte taurocholate uptake was determined using a novel microperfusion technique on intrahepatic bile duct units (IBDUs) derived from C,TCA and CY fed rats. RESULTS: In cholangiocytes,both ASBT and t-ASBT message RNA and protein were significantly decreased in response to TCA feeding compared to C diet.In contrast, message and protein of both bile acid transporters significantly increased following CY feeding compared to C diet.In the ileum,TCA feeding significantly up-regulated both ASBT and t-ASBT message and protein compared to C diet,while CY feeding significantly down-regulated message and protein of both bile acid transporters compared to C diet.As anticipated from alterations in cholangiocyte ASBT expression,the uptake of taurocholate in microperfused IBDUs derived from rats on TCA diet decreased 2.7-fold,whereas it increased 1.7-fold in those on CY diet compared to C diet fed groups. CONCLUSION: These data demonstrate that expression of ASBT and t-ASBT in cholangiocytes is regulated by a negative feedback loop while the expression of these transporters in terminal ileum is modified via positive feedback.Thus, while transcriptional regulatory mechanisms in response to alterations in bile acid pool size are operative in both cholangiocytes and ileocytes,each cell type responds differently to bile acid supplementation and depletion.

鸡OATP1B3互作蛋白筛选及其相关基因的转录表达分析

【目的】筛选鉴定鸡有机阴离子转运多肽1B3(OATP1B3)的互作蛋白,并探究其对鸡蛋绿壳颜色形成的影响,为提高绿壳蛋鸡群体选育准确性提供参考依据。【方法】以真核表达载体p EGFP-SLCO1B3和空载体pEGFP-C1分别转染绿壳型赤水乌骨母鸡蛋壳腺上皮细胞,通过免疫共沉淀(Co-IP)结合液相色谱与串联质谱联用技术(LC-MS/MS)筛选鸡OATP1B3互作蛋白,经GO功能注释分析、KEGG信号通路富集分析及蛋白相互作用网络分析鉴定出与鸡蛋绿壳性状形成相关的OATP1B3互作蛋白。同时,通过构建SLCO1B3基因沉默及过表达载体分别转染蛋壳腺上皮细胞,检测SLCO1B3基因过表达或沉默时部分OATP1B3互作蛋白基因(FXR1、CTTN、RPL12和RPS17)在蛋壳腺上皮细胞中的表达情况,并根据鸡蛋壳颜色分为白壳、浅绿和深绿3种类型,分析蛋壳颜色△a*值与FXR1、CTTN、RPL12和RPS17基因表达的相关性。【结果】共筛选鉴定出37个与鸡OATP1B3相互作用的蛋白,其中FXR1、CTTN、RPL12和RPS17与鸡蛋的绿壳性状有密切关系。SLCO1B3基因过表达能极显著下调蛋壳腺上皮细胞内FXR1基因的表达(P<0.01,下同),显著上调RPL12基因表达(P<0.05,下同),极显著上调RPS17基因表达;当SLCO1B3基因沉默后,蛋壳腺上皮细胞内FXR1和CTTN基因的表达极显著上调,而RPL12基因的表达显著下调。白壳类型赤水乌骨母鸡下丘脑中的FXR1基因相对表达量极显著高于绿壳类型赤水乌骨母鸡,肝脏中的RPL12和RPS17基因相对表达量极显著或显著高于绿壳类型赤水乌骨母鸡;此外,FXR1基因在下丘脑中的相对表达量与蛋壳颜色△a*值极显著正相关,RPL12基因在蛋壳腺和肝脏中的相对表达量与蛋壳颜色△a*值极显著正相关。【结论】筛选鉴定出的37个鸡OATP1B3互作蛋白主要定位于细胞质和细胞核,具有蛋白结合能力及结构分子活性,主要参与细胞过程、生物调节和能量代谢。在鸡壳腺上皮细胞内SLCO1B3基因与FXR1、CTTN、RPL12和RPS17基因间存在调控关系,其中,FXR1和RPL12基因在鸡蛋绿壳性状的形成过程中发挥着重要作用。

Inhibitory effects of apigenin and kaempferol on the essential solute carrier transporters

AIM： To evaluate the inhibitory effects of apigenin and kaempferol on the uptake of several important solute carrier （SLC） transporters.METHODS： Various SLC transporters including the essential human organic anion transporter 1 （OAT1）, OAT2, OAT3 and OAT4 as well as the important organic cation transporter 1 （OCTN1） and OCTN2, were over-expressed in human embryonic kidney （HEK）-293 cells, a well-established cell model of transporter studies. Transport uptake assay was performed 24 h after the transfection. The transport activity was assessed with the uptake of previously determined transporter model substrates and the inhibitory effect of apigenin and kaempferol was evaluated with the substrate uptake in the presence of 10 μmol/L of each compound. Uptake measurements with varying concentrations of inhibitors （ranged from 0.0001 to 50 μmol/L） were performed to further characterize the inhibitory potency of apigenin and kaempferol. The IC50 value （the concentration that inhibits 50% of the transporter function） of each com-pound was then calculated by the nonlinear regression model of Graphpad Prism 6.0 software.RESULTS： Our data indicated that apigenin could potently inhibit the uptake of estrone-3-sulfate （ES） mediated by the HEK-293 cells expressing OAT2, OAT3 and OAT4 as well as the L-ergothioneine uptake via OCTN1-expressing HEK-293 cells. Among these trans-porters, the most prominent inhibition of apigenin was observed in the case of OAT3. Kaempferol showed sig-nifcant inhibitory effects on the uptake of ES mediated through OAT2 and OAT3. Impaired L-ergothioneine uptake due to the presence of kaempferol was also ob-served in OCTN1-expressing HEK-293 cells. Similar to apigenin, kaempferol showed the most potent inhibito-ry effect on OAT3 as well. To further assess the inhibi-tory potencies of these two compounds on the uptake of ES mediated by OAT3-expressing HEK-293 cells, their IC50 values were then determined. Both chemicals showed pronounced inhibitory potencies on OAT3 with the IC50 values of 1.7 ± 0.1 and 1.0 ± 0.1 μmol/L （P 〈 0.01） for apigenin and kaempferol, respectively.CONCLUSION： Both apigenin and kaempferol are po-tent inhibitors of OAT3; precautions will be necessary when co-administrating them with drugs that are sub-strates of OAT3.

Evaluating the regulation of transporter proteins and P-glycoprotein in rats with cholestasis and its implication for digoxin clearance

BACKGROUND Cardiac and hepatic functionality are intertwined in a multifaceted relationship.Pathologic processes involving one may affect the other through a variety of mechanisms,including hemodynamic and membrane transport effects.AIM To better understand the effect of extrahepatic cholestasis on regulations of membrane transporters involving digoxin and its implication for digoxin clearance.METHODS Twelve adult rats were included in this study;baseline hepatic and renal laboratory values and digoxin pharmacokinetic(PK)studies were established before evenly dividing them into two groups to undergo bile duct ligation(BDL)or a sham procedure.After 7 d repeat digoxin PK studies were completed and tissue samples were taken to determine the expressions of cell membrane transport proteins by quantitative western blot and real-time polymerase chain reaction.Data were analyzed using SigmaStat 3.5.Means between pre-surgery and post-surgery in the same experimental group were compared by paired t-test,while independent t-test was employed to compare the means between sham and BDL groups.RESULTS Digoxin clearance was decreased and liver function,but not renal function,was impaired in BDL rats.BDL resulted in significant up-regulation of multidrug resistance 1 expression in the liver and kidney and its down-regulation in the small intestine.Organic anion transporting polypeptides(OATP)1A4 was up-regulated in the liver but down-regulated in intestine after BDL.OATP4C1 expression was markedly increased in the kidney following BDL.CONCLUSION The results suggest that cell membrane transporters of digoxin are regulated during extrahepatic cholestasis.These regulations are favorable for increasing digoxin excretion in the kidney and decreasing its absorption from the intestine to compensate for reduced digoxin clearance due to cholestasis.

Insulin-like growth factor 1 modulates the phosphorylation, expression, and activity of organic anion transporter 3 through protein kinase A signaling pathway

Organic anion transporter 3(OAT3)plays a vital role in removing a broad variety of anionic drugs from kidney,thus avoiding their possible toxicity in the body.In the current study,we investigated the role of insulin-like growth factor 1(IGF-1)in the regulation of OAT3.We showed that IGF-1 induced a dose-and time-dependent increase in OAT3 transport activity,which correlated well with an increase in OAT3 expression.The IGF-1-induced increase in OAT3 expression was blocked by protein kinase A(PKA)inhibitor H89.Moreover,IGF-1 induced an increase in OAT3 phosphorylation,which was also blocked by H89.These data suggest that the IGF-1 modulation of OAT3 occurred through PKA signaling pathway.To further confirm the involvement of PKA,we treated OAT3-expressing cells with PKA activator Bt’2-cAMP,followed by examining OAT activity and phosphorylation.We showed that OAT3 activity and phosphorylation were much enhanced in Bt2-cAMP-treated cells as compared to that in control cells.Finally,linsitinib,an anticancer drug that blocks the IGF-1 receptor,abrogated IGF-1-stimulated OAT3 transport activity.In conclusion,our study demonstrated that IGF-1 regulates OAT3 expression and transport activity through PKA signaling pathway,possibly by phosphorylating the transporter.

Organic anion transporter 1 and 3 contribute to traditional Chinese medicine-induced nephrotoxicity

With the internationally growing popularity of traditional Chinese medicine(TCM), TCM-induced nephropathy has attracted public attention. Minimizing this toxicity is an important issue for future research. Typical nephrotoxic TCM drugs such as Aristolochic acid, Tripterygium wilfordii Hook. f, Rheum officinale Baill, and cinnabar mainly damage renal proximal tubules or cause interstitial nephritis. Transporters in renal proximal tubule are believed to be critical in the disposition of xenobiotics. In this review, we provide information on the alteration of renal transporters by nephrotoxic TCMs, which may be helpful for understanding the nephrotoxic mechanism of TCMs and reducing adverse effects. Studies have proven that when administering nephrotoxic TCMs, the expression or function of renal transporters is altered, especially organic anion transporter 1 and 3. The alteration of these transporters may enhance the accumulation of toxic drugs or the dysfunction of endogenous toxins and subsequently sensitize the kidney to injury.Transporters-related drug combination and clinical biomarkers supervision to avoid the risk of future toxicity are proposed.

板蓝根及所含靛蓝和靛玉红强烈抑制小鼠肾主要有机阴离子转运体Oat1,Oat2和Oat3

目的探讨板蓝根颗粒剂(GRI)和饮片水煎剂(DRI)及其所含主要成分靛蓝和靛玉红对小鼠肾有机阴离子转运体(OAT)中3个主要亚型Oat1,Oat2和Oat3的影响。方法 NIH小鼠分别ig给予GRI0.615和2.460 g·kg-1,DRI 1.6和6.4 g·kg-1(生药量),靛蓝0.008和0.640 mg·kg-1,靛玉红0.0192和1.5360 mg·kg-1,每组60只(雌雄对半),每天2次,连续5 d。同时设丙磺舒(0.05 g·kg-1)阳性对照组和两种溶媒〔纯水和0.5%羧甲纤维素钠(CMC-Na)水溶液〕对照组及糊精加蔗糖(各1.5 g·kg-1)添加剂组。最后1次给予供试物后实施对-氨基马尿酸(PAH,iv,0.03 g·kg-1)清除实验,即在iv PAH后1.0,2.5,5.0,7.5,10.0和20.0 min时每组分别各取10只小鼠(雌雄对半),安乐处死收集全血制备血清,并迅速摘取双肾,右肾进行组织匀浆后测定PAH蓄积量,左肾组织用于提取总m RNA。每组另取10只小鼠(雌雄各半),同样给药处理,按Nakakariya法做肾切片进行摄取PAH实验。用Kiguchi法测定血清和肾组织匀浆液中PAH浓度。以药动学软件(DAS 2.0)计算血清及肾组织中PAH的主要药动学参数。以实时定量PCR法测定小鼠肾组织Oat1,Oat2及Oat3 m RNA表达。结果与纯水对照组比较,0.5%CMC-Na对照组各项检测指标均无显著差异。与两种溶媒对照组相比,GRI 2.460 g·kg-1,靛蓝0.640 mg·kg-1和靛玉红1.5360 mg·kg-1组消除半衰期(t1/2β)显著延长(P<0.05);各供试物组分布容积(Vd)和清除率(Cl)均显著减少(P<0.01),曲线下面积(AUC0→20 min)均显著增加(P<0.01);由采血时间段内各组肾组织中的PAH蓄积量所求得的AUC0→20 min显著大于同期对照组(P<0.05,P<0.01),且肾AUC0→20 min与血液AUC0→20 min的比值在各组间无显著差异。各剂量供试物均可使肾切片摄取PAH的量显著少于对照组(P<0.05,P<0.01)。与纯水/CMC对照组相比,GRI 2.460 g·kg-1,DRI 6.4 g·kg-1,靛蓝0.640 mg·kg-1,靛玉红1.5360 mg·kg-1组小鼠肾组织Oat1,Oat2及Oat3 m RNA表达除靛玉红组Oat2 m RNA(P<0.05)、GRI组Oat3 m RNA(P<0.01)表达水平被显著上调外,其余均被显著下调(P<0.05,P<0.01)。结论 GRI、DRI、靛蓝、靛玉红在所用剂量下对小鼠肾组织Oat1,Oat2及Oat3均有明显抑制作用,GRI和DRI的这种抑制作用可能主要来自其所含的靛蓝和靛玉红成分。

茯苓水提物对高尿酸血症大鼠rURAT1 rOAT1和rOCT2表达的影响

目的考察茯苓水提物对高尿酸血症大鼠肾脏组织中尿酸转运体1(rURAT1)、有机阴离子转运体1(rOAT1)和有机阳离子转运体2(rOCT2)表达的影响,探讨茯苓降低血尿酸水平的机制。方法将右侧肾脏摘除的48只大鼠随机分为6组:手术对照组、模型组、别嘌呤醇阳性对照组,茯苓水提物高、中、低剂量组。药物干预28d,实验期间定期检测血尿酸和血清肌酐水平,采用免疫印迹法检测各组大鼠肾脏组织中rURAT1、rOAT1和rOCT2的表达。结果茯苓水提物高、中、低剂量组的血尿酸水平均较模型组大鼠明显降低;肾脏组织中rOAT1和rOCT2的表达均较模型组大鼠明显升高,而其rURAT较模型组大鼠显著下降,差异均有统计学意义(P<0.05)。结论茯苓水提物通过调节肾脏组织中rURAT1、rOAT1和rOCT2的表达,从而发挥促进高尿酸血症大鼠尿酸的排泄作用。