Acute regulation of OAT3-mediated estrone sulfate transport in isolated rabbit renal proximal tubules.
We investigated the regulation of organic anion transport driven by the organic anion transporter 3 (OAT3), a multispecific OAT localized at the basolateral membrane of the renal proximal tubule. PMA, a PKC activator, inhibited uptake of estrone sulfate (ES), a prototypic substrate for OAT3, in a dose- and time-dependent manner. This inhibition was reduced by 100 nM bisindoylmaleimide I (BIM), a specific PKC inhibitor. The alpha(1)-adrenergic receptor agonist phenylephrine also inhibited ES uptake, and this effect was reduced by BIM. These results suggest that PKC activation downregulates OAT3-mediated organic anion transport. In contrast, epidermal growth factor (EGF) increased ES uptake following activation of MAPK. Exposure to PGE(2) or dibutyryl (db)-cAMP also enhanced ES uptake. Stimulation produced by PGE(2) and db-cAMP was prevented by the PKA inhibitor H-89, indicating that this stimulation required PKA activation. In addition, inhibition of cyclooxygenase 1 (COX1) (but not COX2) inhibited ES uptake. Furthermore, the stimulatory effect of EGF was eliminated by inhibition of either COX1 or PKA. These data suggest that EGF stimulates ES uptake by a process in which MAPK activation results in increased PGE(2) production that, in turn, activates PKA and subsequently stimulates ES uptake. Interestingly, EGF did not induce upregulation immediately following phenylephrine-induced downregulation; and phenylephrine did not induce downregulation immediately after EGF-induced upregulation. These data are the first to show the regulatory response of organic anion transport driven by OAT3 in intact renal proximal tubules.
Soodvilai
S
S
Dept. of Physiology, College of Medicine, University of Arizona, Tucson, AZ 85724, USA.
Chatsudthipong
V
V
Evans
K K
KK
Wright
S H
SH
Dantzler
W H
WH
D000818:Animals; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D015232:Dinoprostone / Q000494:pharmacology; D015536:Down-Regulation / Q000502:physiology; D004789:Enzyme Activation / Q000187:drug effects; D020536:Enzyme Activators / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004970:Estrone / Q000031:analogs & derivatives* / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology; D066298:In Vitro Techniques; D007687:Kidney Tubules, Proximal / Q000378:metabolism*; D029362:Organic Anion Transporters, Sodium-Independent / Q000378:metabolism*; D010656:Phenylephrine / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism / Q000502:physiology; D011817:Rabbits; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D020536:Enzyme Activators; D004791:Enzyme Inhibitors; D029362:Organic Anion Transporters, Sodium-Independent; C114338:organic anion transport protein 3; D010656:Phenylephrine; D004970:Estrone; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D015232:Dinoprostone; D013755:Tetradecanoylphorbol Acetate; C017296:estrone sulfate