Regulation of Expression of Renal Organic Anion Transporters OAT1 and OAT3 in a Model of Ischemia/Reperfusion Injury.
BACKGROUND
Recently, we gained evidence that impairment of rOat1 and rOat3 expression induced by ischemic acute kidney injury (AKI) is mediated by COX metabolites and this suppression might be critically involved in renal damage.


METHODS
(i) Basolateral organic anion uptake into proximal tubular cells after model ischemia and reperfusion (I/R) was investigated by fluorescein uptake. The putative promoter sequences from hOAT1 (SLC22A6) and hOAT3 (SCL22A8) were cloned into a reporter plasmid, transfected into HEK cells and (ii) transcriptional activity was determined after model ischemia and reperfusion as a SEAP reporter gen assay. Inhibitors or antagonists were applied with the beginning of reperfusion.


RESULTS
By using inhibitors of PKA (H89) and PLC (U73122), antagonists of E prostanoid receptor type 2 (AH6809) and type 4 (L161,982), we gained evidence that I/R induced down regulation of organic anion transport is mediated by COX1 metabolites via E prostanoid receptor type 4. The latter signaling was confirmed by application of butaprost (EP2 agonist) or TCS2510 (EP4 agonist) to control cells. In brief, the latter signaling was verified for the transcriptional activity in the reporter gen assay established. Therein, selective inhibitors for COX1 (SC58125) and COX2 (SC560) were also applied.


CONCLUSIONS
Our data show (a) that COX1 metabolites are involved in the regulation of renal organic anion transport(ers) after I/R via the EP4 receptor and (b) that this is due to transcriptional regulation of the respective transporters. As the promoter sequences cloned were of human origin and expressed in a human renal epithelial cell line we (c) hypothesize that the regulatory mechanisms described after I/R is meaningful for humans as well.
Klinik fx00FC;r Anx00E4;sthesie und Operative Intensivmedizin, Universitx00E4;tsklinikum Halle (Saale), Halle (Saale), Germany.
Christina
C
Preising
Reinhard
R
Schneider
Michael
M
Bucher
Michael
M
Gekle
Christoph
C
Sauvant
D001692:Biological Transport / Q000187:drug effects / Q000235:genetics; D002460:Cell Line; D051545:Cyclooxygenase 1 / Q000235:genetics / Q000378:metabolism; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism; D052246:Cyclooxygenase 2 Inhibitors / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D007687:Kidney Tubules, Proximal / Q000187:drug effects / Q000378:metabolism*; D027362:Organic Anion Transport Protein 1 / Q000235:genetics* / Q000378:metabolism*; D029362:Organic Anion Transporters, Sodium-Independent / Q000235:genetics* / Q000378:metabolism*; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000235:genetics; D011448:Prostaglandin Antagonists / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D058309:Receptors, Prostaglandin E, EP4 Subtype / Q000235:genetics / Q000378:metabolism; D015427:Reperfusion Injury / Q000235:genetics* / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects / Q000235:genetics
D052246:Cyclooxygenase 2 Inhibitors; D027362:Organic Anion Transport Protein 1; D029362:Organic Anion Transporters, Sodium-Independent; D010726:Phosphodiesterase Inhibitors; D011448:Prostaglandin Antagonists; D047428:Protein Kinase Inhibitors; D058309:Receptors, Prostaglandin E, EP4 Subtype; C114338:organic anion transport protein 3; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; C496511:PTGS1 protein, human; C496540:PTGS2 protein, human