1
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Han C, Zheng J, Wang F, Lu Q, Chen Q, Hu A, Visentin M, Kullak-Ublick GA, Gai Z, Chu L. The Role of NF-kB in the Downregulation of Organic Cation Transporter 2 Expression and Renal Cation Secretion in Kidney Disease. Front Med (Lausanne) 2022; 8:800421. [PMID: 35059420 PMCID: PMC8763702 DOI: 10.3389/fmed.2021.800421] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Accepted: 12/10/2021] [Indexed: 12/12/2022] Open
Abstract
Organic cation transporter 2 (OCT2), encoded by the SLC22A2 gene, is the main cation transporter on the basolateral membrane of proximal tubular cells. OCT2 facilitates the entry step of the vectorial transport of most cations from the peritubular space into the urine. OCT2 downregulation in kidney disease models is apparent, yet not clear from a mechanistic vantage point. The aim of this study was to explore the role of inflammation, a common thread in kidney disease, and NF-kB in OCT2 modulation and tubular secretion. Among the OCTs, OCT2 was found consistently downregulated in the kidney of rats with chronic kidney disease (CKD) or acute kidney injury (AKI) and in patients diagnosed with CKD, and it was associated with the upregulation of TNFα renal expression. Exposure to TNFα reduced the expression and function of OCT2 in primary renal proximal tubule epithelial cells (RPTEC). Silencing or pharmacological inhibition of NF-kB rescued the expression of OCT2 in the presence of TNFα, indicating that OCT2 repression was NF-kB-dependent. In silico prediction coupled to gene reporter assay demonstrated the presence of at least one functional NF-kB cis-element upstream the transcription starting site of the SLC22A2 gene. Acute inflammation triggered by lipopolysaccharide injection induced TNFα expression and the downregulation of OCT2 in rat kidney. The inflammation did reduce the active secretion of the cation Rhodamine 123, with no impairment of the glomerular filtration. In conclusion, the NF-kB pathway plays a major role in the transcriptional regulation of OCT2 and, in turn, in the overall renal secretory capacity.
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Affiliation(s)
- Chao Han
- Department of Nephrology, Tengzhou Central People's Hospital, Zaozhuang, China
| | - Juan Zheng
- Department of Joint Laboratory for Translational Medicine Research, Liaocheng University/Liaocheng People's Hospital, Liaocheng, China
| | - Fengyi Wang
- Department of Urology, Tengzhou Central People's Hospital, Zaozhuang, China
| | - Qingyang Lu
- Department of Pathology, Liaocheng People's Hospital, Liaocheng, China
| | - Qingfa Chen
- Institute for Tissue Engineering and Regenerative Medicine, Liaocheng University/Liaocheng People's Hospital, Liaocheng, China
| | - Ankang Hu
- Laboratory Animal Center, Xuzhou Medical University, Xuzhou, China
| | - Michele Visentin
- Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Gerd A Kullak-Ublick
- Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Zhibo Gai
- Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.,Innovation Research Institute of Traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Lei Chu
- Department of Urology, The Affiliated Tengzhou Hospital of Xuzhou Medical University, Zaozhuang, China.,Department of Urology, Affiliated Tengzhou Hospital of Jining Medical University, Zaozhuang, China
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2
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Wu X, Yan M, Liu T, Liao J, Zhang J, Chen S, Deng W, Zhang S, Sun B, Zhou H, Ke B. Fucoidan elevates surface organic cation transporter 2 expression via upregulation of protein kinase A in uric acid nephropathy. Exp Ther Med 2017; 14:4153-4159. [PMID: 29104632 PMCID: PMC5658688 DOI: 10.3892/etm.2017.5077] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 03/31/2017] [Indexed: 12/21/2022] Open
Abstract
Uric acid nephropathy (UAN) is caused by excessive uric acid, and is a key risk factor for uric acid nephrolithiasis, gouty arthritis, renal diseases and cardiovascular diseases. The present study aimed to evaluate the protective effect of fucoidan, a sulfated polysaccharide component of brown algae, on UAN and to elucidate the underlying molecular mechanism. A rat model of UAN was induced by adenine treatment, and rats were then randomly assigned to control, model or fucoidan treatment groups. Hematoxylin and eosin staining of the kidney tissues of rats with UAN was subjected to conventional morphological evaluation. Cellular infiltrate in the tubules, atrophic glomeruli, tubular ectasia, granuloma hyperplasia focal fibrosis and accumulated urate crystals in the tubules of UAN rat renal tissues were observed. These symptoms of kidney damage were reduced in the fucoidan treatment group. Periodic acid methenamine silver-Masson staining was performed and the results indicated that renal interstitial fibrosis was reduced among renal tissues from the fucoidan treatment group compared with the model group. Terminal deoxynucleotidyl-transferase-mediated dUTP nick end labelling staining revealed a lower proportion of apoptotic nuclei in the kidneys of the fucoidan treatment group compared with the model group. Protein kinase A (PKA) 2β and phosphorylated PKA 2β protein levels were significantly elevated in renal tissues of the fucoidan treatment group compared with the model group (P<0.05 and P<0.01, respectively), suggesting that PKA expression was upregulated by fucoidan. Immunohistochemistry staining of PKA in rat renal tissues demonstrated increased expression of PKA. The surface organic cation transporter 2 (OCT2) level was significantly increased by fucoidan treatment compared with the model group (P<0.01), with no significant change in total OCT2 level. COS-7 cells ectopically expressing OCT2 were established. It was indicated that fucoidan was able to activate PKA and upregulate surface OCT2 in OCT2-expressing COS-7 cells. This further demonstrated that upregulation of surface OCT2 expression in OCT2-expressing cells was induced by PKA upregulation. In conclusion, fucoidan upregulated surface OCT2 expression in renal tissues to alleviate the symptoms of UAN via upregulated expression of PKA.
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Affiliation(s)
- Xinlin Wu
- Department of Traditional Chinese Medicine, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Miansheng Yan
- Department of Laboratory Medicine, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Taoli Liu
- Department of Traditional Chinese Medicine, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhuhai, Guangdong 519000, P.R. China
| | - Jiantang Liao
- Community Health Service Center of Dongshan, Guangzhou, Guangdong 510030, P.R. China
| | - Jianqing Zhang
- Department of Laboratory Medicine, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Shuqing Chen
- Department of Traditional Chinese Medicine, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Wei Deng
- Department of Traditional Chinese Medicine, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Shijun Zhang
- Department of Traditional Chinese Medicine, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Baoguo Sun
- Department of Traditional Chinese Medicine, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Houming Zhou
- Department of Traditional Chinese Medicine, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Bin Ke
- Department of Traditional Chinese Medicine, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, P.R. China
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3
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Wongwan T, Kittayaruksakul S, Asavapanumas N, Chatsudthipong V, Soodvilai S. Activation of liver X receptor inhibits OCT2-mediated organic cation transport in renal proximal tubular cells. Pflugers Arch 2017; 469:1471-1481. [PMID: 28741179 DOI: 10.1007/s00424-017-2033-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 07/09/2017] [Accepted: 07/11/2017] [Indexed: 01/05/2023]
Abstract
Liver X receptor (LXR) is transcriptional factor that plays an important role in the regulation of energy metabolism such as cholesterol, lipid, and glucose metabolism as well as membrane transporters and channels. Using both in vitro and in vivo models, LXR regulation of the expression and function of renal organic cation transporter 2 (OCT2) was observed. Synthetic LXR agonist (GW3965) and endogenous LXR agonist (22R-hydroxycholesterol) significantly reduced the uptake of 3H-MPP+, a prototypic substrate of OCT2, in both OCT2- Chinese hamster ovary K1 and human renal proximal tubular cells (RPTEC/TERT1). GW3965 decreased transport activity of OCT2 via a reduction of the maximal transport rate of MPP+ without affecting transporter affinity. The inhibitory effect of GW3965 was attenuated by co-treatment with LXR antagonist (fenofibrate) indicating the inhibition was LXR-dependent mechanism. In addition, co-treatment with a retinoic X receptor (RXR) ligand, 9-cis retinoic acid enhanced the inhibitory effect of GW3965, indicating negative regulation of OCT2 transport activity by the LXR/RXR complex. Treatment RPTEC/TERT1 cells with GW3965 significantly reduced OCT2 protein expression without changing mRNA expression. In parallel, the effect of LXR activation on OCT2 function was investigated in intact mouse kidney. Treating mice with 50 mg/kg BW T0901317 for 14 days significantly decreased 3H-MPP+ uptake into renal cortical slices, correlating with decreased OCT2 protein expression in renal cortex without changes in mRNA expression levels. Taken together, LXR/RXR activation downregulates the protein expression and function of OCT2 in renal proximal tubule, suggesting LXR might affect the total profile of renal excretion of cationic compounds.
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Affiliation(s)
- Teerasak Wongwan
- Department of Physiology, Faculty of Science, Mahidol University, Rama VI Road, Rajathevi, Bangkok, 10400, Thailand.,Research Center of Transport Proteins for Medical Innovation, Faculty of Science, Mahidol University, Rajathevi, Bangkok, 10400, Thailand
| | - Suticha Kittayaruksakul
- Department of Physiology, Faculty of Science, Mahidol University, Rama VI Road, Rajathevi, Bangkok, 10400, Thailand
| | - Nithi Asavapanumas
- Department of Physiology, Faculty of Science, Mahidol University, Rama VI Road, Rajathevi, Bangkok, 10400, Thailand
| | - Varanuj Chatsudthipong
- Department of Physiology, Faculty of Science, Mahidol University, Rama VI Road, Rajathevi, Bangkok, 10400, Thailand
| | - Sunhapas Soodvilai
- Department of Physiology, Faculty of Science, Mahidol University, Rama VI Road, Rajathevi, Bangkok, 10400, Thailand. .,Research Center of Transport Proteins for Medical Innovation, Faculty of Science, Mahidol University, Rajathevi, Bangkok, 10400, Thailand. .,Excellent Center for Drug Discovery, Mahidol University, Rama VI Road, Rajathevi, Bangkok, 10400, Thailand.
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4
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Caetano-Pinto P, Jamalpoor A, Ham J, Goumenou A, Mommersteeg M, Pijnenburg D, Ruijtenbeek R, Sanchez-Romero N, van Zelst B, Heil SG, Jansen J, Wilmer MJ, van Herpen CML, Masereeuw R. Cetuximab Prevents Methotrexate-Induced Cytotoxicity in Vitro through Epidermal Growth Factor Dependent Regulation of Renal Drug Transporters. Mol Pharm 2017; 14:2147-2157. [PMID: 28493713 PMCID: PMC5462489 DOI: 10.1021/acs.molpharmaceut.7b00308] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
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The combination of methotrexate with
epidermal growth factor receptor
(EGFR) recombinant antibody, cetuximab, is currently being investigated
in treatment of head and neck carcinoma. As methotrexate is cleared
by renal excretion, we studied the effect of cetuximab on renal methotrexate
handling. We used human conditionally immortalized proximal tubule
epithelial cells overexpressing either organic anion transporter 1
or 3 (ciPTEC-OAT1/ciPTEC-OAT3) to examine OAT1 and OAT3, and the efflux
pumps breast cancer resistance protein (BCRP), multidrug resistance
protein 4 (MRP4), and P-glycoprotein (P-gp) in methotrexate handling
upon EGF or cetuximab treatment. Protein kinase microarrays and knowledge-based
pathway analysis were used to predict EGFR-mediated transporter regulation.
Cytotoxic effects of methotrexate were evaluated using the dimethylthiazol
bromide (MTT) viability assay. Methotrexate inhibited OAT-mediated
fluorescein uptake and decreased efflux of Hoechst33342 and glutathione-methylfluorescein
(GS-MF), which suggested involvement of OAT1/3, BCRP, and MRP4 in
transepithelial transport, respectively. Cetuximab reversed the EGF-increased
expression of OAT1 and BCRP as well as their membrane expressions
and transport activities, while MRP4 and P-gp were increased. Pathway
analysis predicted cetuximab-induced modulation of PKC and PI3K pathways
downstream EGFR/ERBB2/PLCg. Pharmacological inhibition of ERK decreased
expression of OAT1 and BCRP, while P-gp and MRP4 were increased. AKT
inhibition reduced all transporters. Exposure to methotrexate for
24 h led to a decreased viability, an effect that was reversed by
cetuximab. In conclusion, cetuximab downregulates OAT1 and BCRP while
upregulating P-gp and MRP4 through an EGFR-mediated regulation of
PI3K-AKT and MAPKK-ERK pathways. Consequently, cetuximab attenuates
methotrexate-induced cytotoxicity, which opens possibilities for further
research into nephroprotective comedication therapies.
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Affiliation(s)
- Pedro Caetano-Pinto
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University , 3584 CG Utrecht, The Netherlands
| | - Amer Jamalpoor
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University , 3584 CG Utrecht, The Netherlands
| | - Janneke Ham
- Department of Oncology, Radboud University Medical Center , 6525 GA Nijmegen, The Netherlands
| | - Anastasia Goumenou
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University , 3584 CG Utrecht, The Netherlands
| | | | | | | | - Natalia Sanchez-Romero
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University , 3584 CG Utrecht, The Netherlands.,Centro Investigación Biomédica de Aragón (CIBA), 50009 Zaragoza, Spain
| | - Bertrand van Zelst
- Department of Clinical Chemistry, ErasmusMC , 3015 CE Rotterdam, The Netherlands
| | - Sandra G Heil
- Department of Clinical Chemistry, ErasmusMC , 3015 CE Rotterdam, The Netherlands
| | - Jitske Jansen
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University , 3584 CG Utrecht, The Netherlands
| | - Martijn J Wilmer
- Department of Pharmacology and Toxicology, Radboud Institute of Molecular Life Sciences, Radboudumc , 6500 HB Nijmegen, The Netherlands
| | - Carla M L van Herpen
- Department of Oncology, Radboud University Medical Center , 6525 GA Nijmegen, The Netherlands
| | - Rosalinde Masereeuw
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University , 3584 CG Utrecht, The Netherlands
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5
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Young RK, Villalobos ARA. Stress-induced stimulation of choline transport in cultured choroid plexus epithelium exposed to low concentrations of cadmium. Am J Physiol Regul Integr Comp Physiol 2014; 306:R291-303. [PMID: 24401988 DOI: 10.1152/ajpregu.00252.2013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The choroid plexus epithelium forms the blood-cerebrospinal fluid barrier and accumulates essential minerals and heavy metals. Choroid plexus is cited as being a "sink" for heavy metals and excess minerals, serving to minimize accumulation of these potentially toxic agents in the brain. An understanding of how low doses of contaminant metals might alter transport of other solutes in the choroid plexus is limited. Using primary cultures of epithelial cells isolated from neonatal rat choroid plexus, our objective was to characterize modulation of apical uptake of the model organic cation choline elicited by low concentrations of the contaminant metal cadmium (CdCl₂). At 50-1,000 nM, cadmium did not directly decrease or increase 30-min apical uptake of 10 μM [(3)H]choline. However, extended exposure to 250-500 nM cadmium increased [(3)H]choline uptake by as much as 75% without marked cytotoxicity. In addition, cadmium induced heat shock protein 70 and heme oxygenase-1 protein expression and markedly induced metallothionein gene expression. The antioxidant N-acetylcysteine attenuated stimulation of choline uptake and induction of stress proteins. Conversely, an inhibitor of glutathione synthesis l-buthionine-sulfoximine (BSO) enhanced stimulation of choline uptake and induction of stress proteins. Cadmium also activated ERK1/2 MAP kinase. The MEK1 inhibitor PD98059 diminished ERK1/2 activation and attenuated stimulation of choline uptake. Furthermore, inhibition of ERK1/2 activation abated stimulation of choline uptake in cells exposed to cadmium with BSO. These data indicate that in the choroid plexus, exposure to low concentrations of cadmium may induce oxidative stress and consequently stimulate apical choline transport through activation of ERK1/2 MAP kinase.
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6
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Abstract
Organic anions and cations (OAs and OCs, respectively) comprise an extraordinarily diverse array of compounds of physiological, pharmacological, and toxicological importance. The kidney, primarily the renal proximal tubule, plays a critical role in regulating the plasma concentrations of these organic electrolytes and in clearing the body of potentially toxic xenobiotics agents, a process that involves active, transepithelial secretion. This transepithelial transport involves separate entry and exit steps at the basolateral and luminal aspects of renal tubular cells. Basolateral and luminal OA and OC transport reflects the concerted activity of a suite of separate proteins arranged in parallel in each pole of proximal tubule cells. The cloning of multiple members of several distinct transport families, the subsequent characterization of their activity, and their subcellular localization within distinct regions of the kidney, now allows the development of models describing the molecular basis of the renal secretion of OAs and OCs. New information on naturally occurring genetic variation of many of these processes provides insight into the basis of observed variability of drug efficacy and unwanted drug-drug interactions in human populations. The present review examines recent work on these issues.
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Affiliation(s)
- Ryan M Pelis
- Novartis Pharmaceuticals Corp., Translational Sciences, East Hanover, New Jersey, USA
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7
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Asavapanumas N, Kittayaruksakul S, Meetam P, Muanprasat C, Chatsudthipong V, Soodvilai S. Fenofibrate down-regulates renal OCT2-mediated organic cation transport via PPARα-independent pathways. Drug Metab Pharmacokinet 2012; 27:513-9. [PMID: 22473497 DOI: 10.2133/dmpk.dmpk-11-rg-123] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Fibrate drugs, the peroxisome proliferator-activated receptor alpha (PPARα) agonists, are widely prescribed for the treatment of hyperlipidemia. The present study examined the effect of fibrate drugs on renal OCT2 activity in a heterologous cell system [Chinese hamster ovary (CHO-K1) cells stably transfected with rabbit (rb) OCT2], LLC-PK1, and intact mouse renal cortical slices. We found that both in the CHO-K1 cells expressing rbOCT2 and in LLC-PK1 cells, fenofibrate significantly inhibited [³H]-MPP⁺ uptake whereas clofibrate and WY14643 had no effect. Surprisingly, the inhibitory effect of fenofibrate was not attenuated by GW6471, a PPARα antagonist, indicating that the inhibitory process observed was via a PPARα-independent pathway. Fenofibrate decreased [³H]-MPP⁺ uptakes through a reduction of the maximal transport (J(max)) but without effect on the transporter affinity (K(t)) corresponding to a decrease in membrane expression of OCT2. Since the inhibitory effect of fenofibrate was not prevented by pretreatment with cycloheximide, its inhibitory action did not involve an inhibition of protein synthesis. Similar to the effect seen in the cell-cultured system, the inhibitory effect of fenofibrate was also observed in intact renal cortical slices. Taken together, our data showed that fenofibrate decreased the activity of OCT2 by reducing the number of functional transporters on the membrane, which is likely to be a PPARα-independent pathway.
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Affiliation(s)
- Nithi Asavapanumas
- Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
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8
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Grabner A, Brast S, Sucic S, Bierer S, Hirsch B, Pavenstädt H, Sitte HH, Schlatter E, Ciarimboli G. LAPTM4A interacts with hOCT2 and regulates its endocytotic recruitment. Cell Mol Life Sci 2011; 68:4079-90. [PMID: 21553234 PMCID: PMC11114991 DOI: 10.1007/s00018-011-0694-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Revised: 04/05/2011] [Accepted: 04/19/2011] [Indexed: 01/06/2023]
Abstract
Human organic cation transporter 2 (hOCT2) is involved in the transport of endogenous and exogenous organic cations mainly in cells of the kidney and the brain. Here, we focus on the regulation of hOCT2 by direct protein-protein interaction. Screening within a mating-based split-ubiquitin-yeast-two-hybrid system (mBSUS) revealed the lysosomal-associated protein transmembrane 4 alpha (LAPTM4A) as a potential interacting protein. Interaction of LAPTM4A and hOCT2 was confirmed by pulldown assays, FRET microscopy analysis and immunofluorescence microscopy. Functionally, overexpression of LAPTM4A significantly decreased ASP(+) uptake in HEK293 cells stably transfected with hOCT2, suggesting a negative regulation of hOCT2-mediated transport. Furthermore, overexpression of LAPTM4A leads to a significantly decreased hOCT2 plasma membrane expression in surface biotinylation experiments. In addition, significant expression of LAPTM4A in human kidney was demonstrated by immunoblotting and immunofluorescence.In this work, LAPTM4A has been identified as interaction partner of hOCT2. LAPTM4A regulates the function of hOCT2 by influencing its trafficking to/from the cell membrane and processing it via the intracellular sorting machinery.
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Affiliation(s)
- A Grabner
- Medizinische Klinik und Poliklinik D, Abteilung für Experimentelle Nephrologie, Universitätsklinikum Münster, Domagkstrasse 3A, 48149 Münster, Germany.
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9
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Soodvilai S, Nantavishit J, Muanprasat C, Chatsudthipong V. Renal organic cation transporters mediated cadmium-induced nephrotoxicity. Toxicol Lett 2011; 204:38-42. [DOI: 10.1016/j.toxlet.2011.04.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Revised: 04/04/2011] [Accepted: 04/05/2011] [Indexed: 12/21/2022]
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10
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Properties and regulation of organic cation transport in freshly isolated mouse proximal tubules analyzed with a fluorescence reader-based method. Pflugers Arch 2011; 462:359-69. [PMID: 21523352 DOI: 10.1007/s00424-011-0969-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Revised: 04/06/2011] [Accepted: 04/11/2011] [Indexed: 01/08/2023]
Abstract
The main elimination site of organic cations (OCs) is the renal proximal tubule (PT). OC transporters (OCT) accept endogenous and exogenous substances and xenobiotics. As transgenic mouse models are increasingly used in translational medicine, functional properties with special focus on regulation of OCT of isolated mouse PTs were studied with a new fluorescence reader-based method, which allows studying larger numbers of tubules per kidney. OC transport across the basolateral membrane of PTs from male mice was measured as initial uptake of the fluorescent dye 4-(4-(dimethylamino)styryl)-N-methylpyridinium (ASP). A microtiter plate fluorescence reader was used to semi-automatically analyze OC transport in freshly isolated tubules. Relative mRNA expression of OCT1/OCT2/OCT3 in PTs was 1/0.3/0.01 and did not vary from S1 to S3 segments. ASP was transported by PTs with a K (m) of 6 μM. It was inhibited by TEA, TPA, or cimetidine (IC(50)=5, 19, or 53 μM, respectively). Angiotensin II stimulated ASP uptake (+63%), while stimulation of PKC reduced (-37%) OC transport. Inhibition of p56(lck) tyrosine kinase (-60%), of PI3K (-36%), of Ca(2+)/calmodulin (-25%), or of PKA (-33%) reduced OC transport. In PTs from OCT1/2(-/-) mice ASP uptake was reduced to ~20%. Using this fluorescence reader-based method, we report substrate specificities and a complex pattern of acute regulation of OC transport in isolated mouse PTs. Compared to isolated human PTs or rat and human OCT isoforms expressed in HEK293-cells, OC transport across the basolateral membrane of freshly isolated mouse PTs shows similarities but also specific differences.
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11
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Saito H. Pathophysiological regulation of renal SLC22A organic ion transporters in acute kidney injury: Pharmacological and toxicological implications. Pharmacol Ther 2010; 125:79-91. [DOI: 10.1016/j.pharmthera.2009.09.008] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Accepted: 09/30/2009] [Indexed: 01/27/2023]
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12
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Abstract
1. Organic cation transporters (OCTs) translocate endogenous (e.g. dopamine) and exogenous (e.g. drugs) substances of cationic nature and, therefore, play an important role in the detoxification of exogenous compounds. This review aims to furnish essential information on OCTs, with an emphasis on pharmacological aspects. 2. Analysis of the literature on OCTs makes clear that there is a species- and organ-specific distribution of the different isoforms, which can also be differentially regulated. OCTs are responsible for the excretion and/or distribution of many drugs and also for serious tissue-specific side-effects such as cisplatin-induced nephrotoxicity. The presence of single nucleotide polymorphisms in these transporters significantly influences the response of patients to medication, as demonstrated for the antidiabetic drug metformin. 3. A substantial amount of research has to be undertaken to clarify further the OCT structure-function relationships specifically to define the role of oligomerization on their activity and regulation, to identify intracellular interaction partners of OCTs, and to characterize their pharmacogenetic aspects.
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Affiliation(s)
- G Ciarimboli
- Medizinische Klinik und Poliklinik D, Experimentelle Nephrologie, Universitatsklinikum Munster, Germany.
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13
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Sweet DH. Kinase signaling pathways regulate fine tuning of transporter activity. Am J Physiol Renal Physiol 2007; 293:F20. [PMID: 17409280 DOI: 10.1152/ajprenal.00126.2007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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