Dual pathways for organic anion secretion in renal proximal tubule

To examine possible regulatory control of renal proximal tubule organic anion secretion, winter flounder (Pleuronectes americanus) proximal tubule primary cultures were mounted in Ussing chambers. Unidirectional fluxes of [2,4-(14)C]dichlorophenoxyacetic acid were determined under short-circuited conditions. Phorbol 12-myristate 13-acetate (1 microM) caused a significant (P < 0.01) inhibition of net 2,4-dichlorophenoxyacetic acid secretion. Preincubation with staurosporine (1 microM) blocked the phorbol 12-myristate 13-acetate-induced decrease in secretion. Neither forskolin (10 microM) nor W-7 (20 microM) had any effect on net transport. Elevation of intracellular calcium activity with either A-23187 or thapsigargin produced a slight, transient decrease in transport. Addition of dopamine (1 microM) to the peritubular side, but not the luminal side, caused a significant (P < 0.01) decrease in net secretion. Both the alpha-adrenergic agonist oxymetazoline (10 microM) and depletion of intracellular Na+ transiently, but significantly (P < 0.05), increased net transport. The data indicate that renal organic anion excretion may be regulated through dopaminergic inhibition and alpha-adrenergic stimulation of net transepithelial secretion.

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Molecular pharmacology of renal organic anion transporters

AJP Renal Physiology ◽

10.1152/ajprenal.2000.279.2.f216 ◽

2000 ◽

Vol 279 (2) ◽

pp. F216-F232 ◽

Cited By ~ 96

Author(s):

Rémon A. M. H. Van Aubel ◽

Rosalinde Masereeuw ◽

Frans G. M. Russel

Keyword(s):

Proximal Tubule ◽

Organic Anion ◽

Tubular Secretion ◽

Renal Proximal Tubule ◽

The Body ◽

Transport Systems ◽

Organic Anion Transporters ◽

Anion Secretion ◽

Anion Transporters ◽

Carrier Mediated Transport

Renal organic anion transport systems play an important role in the elimination of drugs, toxic compounds, and their metabolites, many of which are potentially harmful to the body. The renal proximal tubule is the primary site of carrier-mediated transport from blood to urine of a wide variety of anionic substrates. Recent studies have shown that organic anion secretion in renal proximal tubule is mediated by distinct sodium-dependent and sodium-independent transport systems. Knowledge of the molecular identity of these transporters and their substrate specificity has increased considerably in the past few years by cloning of various carrier proteins. However, a number of fundamental questions still have to be answered to elucidate the participation of the cloned transporters in the overall tubular secretion of anionic xenobiotics. This review summarizes the latest knowledge on molecular and pharmacological properties of renal organic anion transporters and homologs, with special reference to their nephron and plasma membrane localization, transport characteristics, and substrate and inhibitor specificity. A number of the recently cloned transporters, such as the p-aminohippurate/dicarboxylate exchanger OAT1, the anion/sulfate exchanger SAT1, the peptide transporters PEPT1 and PEPT2, and the nucleoside transporters CNT1 and CNT2, are key proteins in organic anion handling that possess the same characteristics as has been predicted from previous physiological studies. The role of other cloned transporters, such as MRP1, MRP2, OATP1, OAT-K1, and OAT-K2, is still poorly characterized, whereas the only information that is available on the homologs OAT2, OAT3, OATP3, and MRP3–6 is that they are expressed in the kidney, but their localization, not to mention their function, remains to be elucidated.

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Organic anion secretion in polycystic kidney disease.

Journal of the American Society of Nephrology ◽

10.1681/asn.v881222 ◽

1997 ◽

Vol 8 (8) ◽

pp. 1222-1231

Author(s):

G A Tanner ◽

N Gretz ◽

Y Shao ◽

A P Evan ◽

M Steinhausen

Keyword(s):

Kidney Disease ◽

Polycystic Kidney Disease ◽

Organic Anion ◽

Left Kidney ◽

Organic Anions ◽

Maximal Rate ◽

Polycystic Kidney ◽

Fluid Accumulation ◽

Anion Secretion ◽

Organic Anion Secretion

This study examined whether organic anion secretion contributes to fluid accumulation in cysts in polycystic kidney disease. Clearance and micropuncture studies were done on young (7 to 16 wk old), mostly male, heterozygous Han:SPRD cystic rats and healthy control littermate rats. Heterozygous Han:SPRD rats manifest a slowly progressive autosomal dominant polycystic kidney disease that closely resembles the human disorder. Left kidney GFR (polyfructosan clearance), in microl/min per 100 g body wt, averaged 331 +/- 36 (SD) in seven healthy rats and 278 +/- 75 in seven cystic rats. The maximal rate of p-aminohippurate (PAH) secretion, in micromol/min per 100 g body wt, averaged 0.94 +/- 0.24 in healthy rats and 0.83 +/- 0.11 in cystic rats. In these young rats, there were no significant differences in GFR or the maximal rate of PAH secretion despite the presence of cystic disease. Using fluorescence microscopy, it was found that 27 of 29 proximal cysts secreted sulfonefluorescein, an organic anion transported by the PAH system. Transmission electron micrographs of superficial cysts that had secreted sulfonefluorescein demonstrated the presence of both normal-appearing and poorly differentiated proximal tubule cells. Segments of superficial proximal convoluted tubules or cysts, isolated by upstream and downstream wax blocks, failed to accumulate fluid when PAH was infused intravenously. With the stationary microperfusion technique, PAH secretion by both normal and cystic nephrons was demonstrated. It is concluded that most proximal cystic epithelia retain the ability to secrete organic anions. Secretion of organic anions, however, does not appear to contribute in any substantial way to fluid accumulation in cysts in the rat kidney.

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Remote sensing and signaling in kidney proximal tubules stimulates gut microbiome-derived organic anion secretion

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1821809116 ◽

2019 ◽

Vol 116 (32) ◽

pp. 16105-16110 ◽

Cited By ~ 18

Author(s):

Jitske Jansen ◽

Katja Jansen ◽

Ellen Neven ◽

Ruben Poesen ◽

Amr Othman ◽

...

Keyword(s):

Proximal Tubule ◽

Gut Microbiome ◽

Organic Anion ◽

Organic Anion Transporter ◽

Indoxyl Sulfate ◽

Regulation Mechanism ◽

Uremic Toxin ◽

Proximal Tubule Cell ◽

Anion Secretion ◽

Anion Transporter

Membrane transporters and receptors are responsible for balancing nutrient and metabolite levels to aid body homeostasis. Here, we report that proximal tubule cells in kidneys sense elevated endogenous, gut microbiome-derived, metabolite levels through EGF receptors and downstream signaling to induce their secretion by up-regulating the organic anion transporter-1 (OAT1). Remote metabolite sensing and signaling was observed in kidneys from healthy volunteers and rats in vivo, leading to induced OAT1 expression and increased removal of indoxyl sulfate, a prototypical microbiome-derived metabolite and uremic toxin. Using 2D and 3D human proximal tubule cell models, we show that indoxyl sulfate induces OAT1 via AhR and EGFR signaling, controlled by miR-223. Concomitantly produced reactive oxygen species (ROS) control OAT1 activity and are balanced by the glutathione pathway, as confirmed by cellular metabolomic profiling. Collectively, we demonstrate remote metabolite sensing and signaling as an effective OAT1 regulation mechanism to maintain plasma metabolite levels by controlling their secretion.

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Liver X receptor activation downregulates organic anion transporter 1 (OAT1) in the renal proximal tubule

AJP Renal Physiology ◽

10.1152/ajprenal.00341.2011 ◽

2012 ◽

Vol 302 (5) ◽

pp. F552-F560 ◽

Cited By ~ 11

Author(s):

Suticha Kittayaruksakul ◽

Sunhapas Soodvilai ◽

Nithi Asavapanumas ◽

Chatchai Muanprasat ◽

Varanuj Chatsudthipong

Keyword(s):

Proximal Tubule ◽

Organic Anion ◽

Basolateral Membrane ◽

Receptor Activation ◽

Inhibitory Effect ◽

Renal Proximal Tubule ◽

Organic Anion Transporter ◽

Anion Transporter ◽

X Receptors ◽

Lxr Agonists

Liver X receptors (LXRs) play an important role in the regulation of cholesterol by regulating several transporters. In this study, we investigated the role of LXRs in the regulation of human organic anion transporter 1 (hOAT1), a major transporter localized in the basolateral membrane of the renal proximal tubule. Exposure of renal S2 cells expressing hOAT1 to LXR agonists (TO901317 and GW3965) and their endogenous ligand [22(R)-hydroxycholesterol] led to the inhibition of hOAT1-mediated [14C]PAH uptake. This inhibition was abolished by coincubation of the above agonists with 22(S)-hydroxycholesterol, an LXR antagonist. Moreover, it was found that the effect of LXR agonists was not mediated by changes in intracellular cholesterol levels. Interestingly, the inhibitory effect of LXRs was enhanced in the presence of 9- cis retinoic acid, a retinoic X receptor agonist. Kinetic analysis revealed that LXR activation decreased the maximum rate of PAH transport ( Jmax) but had no effect on the affinity of the transporter ( Kt). This result correlated well with data from Western blot analysis, which showed the decrease in hOAT1 expression following LXR activation. Similarly, TO901317 inhibited [14C]PAH uptake by the renal cortical slices as well as decreasing mOAT1 protein expression in mouse kidney. Our findings indicated for the first time that hOAT1 was downregulated by LXR activation in the renal proximal tubule.

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Confocal microscopic analysis of fluorescein compartmentation within crab urinary bladder cells

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1994.267.1.r16 ◽

1994 ◽

Vol 267 (1) ◽

pp. R16-R25 ◽

Cited By ~ 6

Author(s):

D. S. Miller ◽

D. M. Barnes ◽

J. B. Pritchard

Keyword(s):

Urinary Bladder ◽

Proximal Tubule ◽

Organic Anion ◽

Microscopic Analysis ◽

Microtubule Inhibitor ◽

Cancer Borealis ◽

Anion Secretion ◽

Bladder Cells

Fluorescein (FL), a fluorescent organic anion, is compartmentalized in cells of organic anion-secreting epithelia, e.g., OK cells, teleost proximal tubule, and crab (Cancer borealis) urinary bladder, a proximal tubule analogue. To further examine the processes involved, FL uptake and distribution were studied in C. borealis urinary bladder cells using epifluorescence and laser confocal microscopy combined with video-image analysis. Intracellular FL was about evenly split between diffuse and punctate compartments after in vitro or in vivo loading. Treatments that affected FL transport into cells (incubation with p-aminohippuric acid or glutarate) altered the FL content of both compartments. However, nocodazole, a microtubule inhibitor, did not affect diffuse FL but significantly reduced punctate FL. Finally, confocal analysis indicated that individual sites of punctate FL accumulation moved in the secretory direction at 0.83 micron/min. Nocodazole nearly abolished this movement and significantly reduced transepithelial organic anion secretion. Thus, in crab urinary bladder, a substantial fraction of total cellular FL is sequestered in vesicles, and these vesicles move in the secretory direction, by a microtubule-dependent process.

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Modulation of the Basolateral and Apical Step of Transepithelial Organic Anion Secretion in Proximal Tubular Opossum Kidney Cells

Journal of Biological Chemistry ◽

10.1074/jbc.m007046200 ◽

2001 ◽

Vol 276 (18) ◽

pp. 14695-14703 ◽

Cited By ~ 27

Author(s):

Christoph Sauvant ◽

Hildegard Holzinger ◽

Michael Gekle

Keyword(s):

Organic Anion ◽

Kidney Cells ◽

Opossum Kidney ◽

Anion Secretion ◽

Opossum Kidney Cells ◽

Proximal Tubular ◽

Organic Anion Secretion

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Organic anion transporter 3 (Slc22a8) is a dicarboxylate exchanger indirectly coupled to the Na+gradient

AJP Renal Physiology ◽

10.1152/ajprenal.00405.2002 ◽

2003 ◽

Vol 284 (4) ◽

pp. F763-F769 ◽

Cited By ~ 133

Author(s):

Douglas H. Sweet ◽

Lauretta M. S. Chan ◽

Ramsey Walden ◽

Xiao-Ping Yang ◽

David S. Miller ◽

...

Keyword(s):

Proximal Tubule ◽

Organic Anion ◽

Renal Proximal Tubule ◽

Organic Anion Transporter ◽

Xenopus Laevis Oocytes ◽

Estrone Sulfate ◽

Anion Transporter ◽

Renal Proximal Tubule Cells ◽

Rat Renal Cortical Slices ◽

Cortical Slices

Basolateral uptake of organic anions in renal proximal tubule cells is indirectly coupled to the Na+ gradient through Na+-dicarboxylate cotransport and organic anion/dicarboxylate exchange. One member of the organic anion transporter (OAT) family, Oat1, is expressed in the proximal tubule and is an organic anion/dicarboxylate exchanger. However, a second organic anion carrier, Oat3, is also highly expressed in the renal proximal tubule, but its mechanism is unclear. Thus we have assessed Oat3 function in Xenopus laevis oocytes and rat renal cortical slices. Probenecid-sensitive uptake of p-aminohippurate (PAH, an Oat1 and Oat3 substrate) and estrone sulfate (ES, an Oat3 substrate) in rat Oat3-expressing oocytes was significantly trans-stimulated by preloading the oocytes with the dicarboxylate glutarate (GA). GA stimulation of ES transport by oocytes coexpressing rabbit Na+-dicarboxylate cotransporter 1 and rat Oat3 was significantly inhibited when the preloading medium contained Li+ or methylsuccinate (MS) or when Na+ was absent. All these treatments inhibit the Na+-dicarboxylate cotransporter, but not rat Oat3. Li+, MS, and Na+ removal had no effect when applied during the ES uptake step, rather than during the GA preloading step. Concentrative ES uptake in rat renal cortical slices was also demonstrated to be probenecid and Na+ sensitive. Accumulation of ES was stimulated by GA, and this stimulation was completely blocked by probenecid, Li+, MS, taurocholate, and removal of Na+. Thus Oat3 functions as an organic anion/dicarboxylate exchanger that couples organic anion uptake indirectly to the Na+ gradient.

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