Regulation of Expression of Renal Organic Anion Transporters OAT1 and OAT3 in a Model of Ischemia/Reperfusion Injury

Abstract

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. Conclusion: 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.

Roles of the Exogenous H2S-Mediated SR-A Signaling Pathway in Renal Ischemia/ Reperfusion Injury in Regulating Endoplasmic Reticulum Stress-Induced Autophagy in a Rat Model

“…Currently, effective therapeutic regimens for the prevention of renal IRI are urgently needed. It has been proven that propofol, COX metabolites and MiR-155 can mediate renal IRI [6-8], but researchers have focused their attention on the attenuation of endoplasmic reticulum (ER) stress and autophagy for their therapeutic potential [9-11]. …”

Increased Fatty Acid Oxidation in Differentiated Proximal Tubular Cells Surviving a Reversible Episode of Acute Kidney Injury

“…There are indeed phenotypic changes in tubular cells and the expression of surface molecules including transporters is well documented. For instance, the decline in the expression of Organic Anion transporter 1 and 3 is transcriptionally mediated by COX1 metabolites after ischemia [26]. If it appears that the uremia is an influence on the expression of these epithelial proteins, [27] in our case, it is indeed a consequence of the first ischemic hit, because the levels of uremia are relatively low.…”

Age-associated differences in transporter gene expression in kidneys of male rats

“…OAT expression is markedly altered during renal failure (31). The importance of OAT1 and 3 in HgCl 2 and MeHg-induced renal injury has been documented (8,10,11,32). In addition, our recent studies revealed the alterations of OAT1 and 3 in HgCl 2 -induced acute and subacute renal injury, but not following exposure to HgS (33,34).…”