Involvement of guanylyl cyclase and cGMP in the regulation of Mrp2-mediated transport in the proximal tubule

Abstract

, and PKC, decreases cell-to-lumen organic anion transport mediated by the multidrug resistance protein isoform 2 (Mrp2). In the present study, we examined the roles of guanylyl cyclase and cGMP in ET signaling to Mrp2. Using confocal microscopy and quantitative image analysis to measure Mrp2-mediated transport of the fluorescent drug fluorescein methotrexate (FL-MTX), we found that oxadiazole quinoxalin (ODQ), an inhibitor of NO-sensitive guanylyl cyclase, blocked ET-1 signaling. ODQ was also effective when signaling was initiated by nephrotoxicants (gentamicin, amikacin, diatrizoate, HgCl 2, and CdCl 2), which appear to stimulate ET release from the tubules themselves. ODQ blocked the effects of the NO donor sodium nitroprusside but not of the phorbol ester that activates PKC. Exposing tubules to 8-bromo-cGMP (8-BrcGMP), a cell-permeable cGMP analog, decreased luminal FL-MTX accumulation. This effect was abolished by bisindoylmaleimide (BIM), a PKC inhibitor, but not by N G -methyl-L-arginine, a NOS inhibitor. Together, these data indicate that ET regulation of Mrp2 involves activation of guanylyl cyclase and generation of cGMP. Signaling by cGMP follows NO release and precedes PKC activation.

Endothelin and calciotropic hormones share regulatory pathways in multidrug resistance protein 2-mediated transport

“…The concentration dependence of the resbPTHrP effect and the firmly established bioactivity in homologous (sea bream) and heterologous (killifish) assays further substantiate this role of PTHrP in kidney function. In line with our observations are earlier reports that PKC activators inhibit Mrp2, whereas ODQ, a guanylate cyclase inhibitor, prevents Mrp2 inhibition (26,34). Moreover, the PKC inhibitor calphostin C abolishes the inhibitory effect of ET-1 on Mrp2 (26) and of PTH (the present study).…”

Increased Apical Insertion of the Multidrug Resistance Protein 2 (MRP2/ABCC2) in Renal Proximal Tubules following Gentamicin Exposure

“…In contrast with our previous findings (Terlouw et al, 2001;Notenboom et al, 2002Notenboom et al, , 2004), we did not observe an initial decrease in MRP2-mediated transport after a shortterm exposure to gentamicin. After short-term exposure, concentrations of up to 1000 M gentamicin in cells or 100 M in perfused rat kidney did not affect Mrp2-mediated transport.…”

“…Important signals in these events are provoked by hormones, protein kinases, and nuclear receptors. Gentamicin is known to trigger several signaling molecules involved in the short-term and long-term regulation of Mrp2, including endothelin, nitric oxide, cGMP, and protein kinase C (Masereeuw et al, 2000;Terlouw et al, 2001;Notenboom et al, 2002Notenboom et al, , 2004. In mammalian hepatocytes, both protein kinase C and protein kinase A have been implicated in bidirectional, regulated trafficking of MRP2 between intracellular stores and the canalicular membrane (Roelofsen et al, 1998;Beuers et al, 2001;Kubitz et al, 2001).…”

“…Less dramatic changes in Mrp2 were observed after exposure to the nephrotoxic antibiotic agent gentamicin using a killfish renal model. Exposure to gentamicin results in a rapid reduction in Mrp2, triggered by an endothelin (ET) signaling pathway (Masereeuw et al, 2000;Terlouw et al, 2001;Notenboom et al, 2002Notenboom et al, , 2004. However, an increase in Mrp2-mediated transport and protein expression was observed in tubules after a 24-h recovery period following a short-term exposure (Notenboom et al, 2005).…”

Regulatory Pathways for ATP-binding Cassette Transport Proteins in Kidney Proximal Tubules

“…An autocrine signaling pathway involving the vasoactive hormone, endothelin-1, that regulates P-gp and Mrp2 in response to several nephrotoxic agents in renal proximal tubules, was previously demonstrated (50,51). The signaling pathway was discovered originally in lower vertebrate, killifish renal tubules, but later demonstrated in rats in vivo and in MDCKII cells over-expressing human MRP2.…”