title: Proximal tubular efflux transporters involved in renal excretion of p-cresyl sulfate and p-cresyl glucuronide: Implications for chronic kidney disease pathophysiology.
abstract: The uremic solutes p-cresyl sulfate (pCS) and p-cresyl glucuronide (pCG) accumulate in patients with chronic kidney disease (CKD), and might contribute to disease progression. Moreover, retention of these solutes may directly be related to renal tubular function. Here, we investigated the role of the efflux transporters Multidrug Resistance Protein 4 (MRP4) and Breast Cancer Resistance Protein (BCRP) in pCS and pCG excretion, and studied the impact of both solutes on the phenotype of human conditionally immortalized renal proximal tubule epithelial cells (ciPTEC). Our results show that p-cresol metabolites accumulate during CKD, with a shift from sulfation to glucuronidation upon progression. Moreover, pCS inhibited the activity of MRP4 by 40% and BCRP by 25%, whereas pCG only reduced MRP4 activity by 75%. Moreover, BCRP-mediated transport of both solutes was demonstrated. Exposure of ciPTEC to pCG caused epithelial-to-mesenchymal transition, indicated by increased expression of vimentin and Bcl-2, and diminished E-cadherin. This was associated with altered expression of key tubular transporters. In conclusion, BCRP is likely involved in the renal excretion of both solutes, and pCG promotes phenotypical changes in ciPTEC, supporting the notion that uremic toxins may be involved in CKD progression by negatively affecting renal tubule cell phenotype and functionality.
authors.affiliation: Department of Pharmacology and Toxicology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands; Department of Physiology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands; Department of Pediatrics, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands; Department of Pharmaceutical Technology and Biopharmacy, University of Groningen, Groningen, The Netherlands.
authors.forename: Henricus A M
authors.initials: HA
authors.lastname: Mutsaers
authors.affiliation: Department of Pharmacology and Toxicology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands; Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, The Netherlands.
authors.forename: Pedro
authors.initials: P
authors.lastname: Caetano-Pinto
authors.affiliation: Department of Pharmacology and Toxicology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands.
authors.forename: Andries E M
authors.initials: AE
authors.lastname: Seegers
authors.affiliation: Department of Pharmacology and Toxicology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands.
authors.forename: Anita C A
authors.initials: AC
authors.lastname: Dankers
authors.affiliation: Department of Pharmacology and Toxicology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands.
authors.forename: Petra H H
authors.initials: PH
authors.lastname: van den Broek
authors.affiliation: Department of Nephrology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands.
authors.forename: Jack F M
authors.initials: JF
authors.lastname: Wetzels
authors.affiliation: Department of Nephrology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands.
authors.forename: Jan A J G
authors.initials: JA
authors.lastname: van den Brand
authors.affiliation: Department of Pediatrics, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands; Department of Pediatrics, Catholic University Leuven, Leuven, Belgium.
authors.forename: Lambertus P
authors.initials: LP
authors.lastname: van den Heuvel
authors.affiliation: Department of Physiology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands.
authors.forename: Joost G
authors.initials: JG
authors.lastname: Hoenderop
authors.affiliation: Department of Pharmacology and Toxicology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands.
authors.forename: Martijn J G
authors.initials: MJ
authors.lastname: Wilmer
authors.affiliation: Department of Pharmacology and Toxicology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands; Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, The Netherlands. Electronic address: r.masereeuw@uu.nl.
authors.forename: Rosalinde
authors.initials: R
authors.lastname: Masereeuw
mesh_terms: D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D000328:Adult; D000368:Aged; D016367:Baculoviridae / Q000235:genetics; D002460:Cell Line; D003408:Cresols / Q000378:metabolism*; D005260:Female; D020719:Glucuronides / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D007687:Kidney Tubules, Proximal / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D065667:Renal Elimination; D051436:Renal Insufficiency, Chronic / Q000378:metabolism; D013463:Sulfuric Acid Esters / Q000378:metabolism*; D014161:Transduction, Genetic
chemical_list: D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D003408:Cresols; D020719:Glucuronides; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D009363:Neoplasm Proteins; D013463:Sulfuric Acid Esters; C485699:4-cresylglucuronide; C073492:ABCC4 protein, human; C116614:ABCG2 protein, human; C408690:4-cresol sulfate
keywords: Chronic kidney disease; Efflux transporters; Nephrotoxicity; Proximal tubule cells; Uremic retention solutes