The vertebrate renal proximal tubule is responsible for the excretory transport of a large number of potentially toxic chemicals, including, waste products of normal metabolism, drugs, environmental pollutants and drug and pollutant metabolites. These chemicals are handled by multiple specific, transport proteins that remove them from the blood and concentrate them in urine. Our research focus is understanding control of these transporters. We use comparative models (intact proximal tubules from teleost fish and mammalian renal slices and cells in culture) in combination with confocal microscopy to identify the physiologically relevant extracellular signals (hormones, metabolites, xenobiotics), and the intracellular signaling pathways that modulate xenobiotic excretion in proximal tubule. Our experiments show separate mechanisms for short-term and long-term regulation of transport. In the short-term, all xenobiotic transport systems in proximal tubule are under control of hormones acting through protein kinase C (PKC). For example, endothelin (ET), acting through a basolateral, B-type ET receptor, a G-protein and PKC, rapidly (minutes) reduces transport mediated by the luminal ATP-driven xenobiotic export pumps, p-glycoprotein and Mrp2, while parathyroid hormone (PTH) acting through a basolateral receptor and PKC rapidly reduces organic anion transport mediated by the basolateral transporters Oat1/3. Recent experiments indicate that 1) nitric oxide is generated after ET binds to its receptor but before PKC activation, and 2) three structurally unrelated classes of nephrotoxicants (radiocontrast agents, aminoglycoside antibiotics and heavy metal salts) release ET from the tubules and thus fire the ET B-receptor-NO-PKC signaling pathway. This appears to be an early, common event in nephrotoxicant action which provides a possible link between ET-signaling and nephrotoxicity. Finally, over the longer-term, (hours to days) low concentrations of heavy metals, such as, Zn and Cd, upregulate transport mediated by Mrp2 and increase the Mrp2 content of the tubules.

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Intramural Research (Z01)
Project #
1Z01ES080056-06
Application #
6673248
Study Section
(LPC)
Project Start
Project End
Budget Start
Budget End
Support Year
6
Fiscal Year
2002
Total Cost
Indirect Cost
Name
U.S. National Inst of Environ Hlth Scis
Department
Type
DUNS #
City
State
Country
United States
Zip Code
Wever, Kim E; Masereeuw, Rosalinde; Miller, David S et al. (2007) Endothelin and calciotropic hormones share regulatory pathways in multidrug resistance protein 2-mediated transport. Am J Physiol Renal Physiol 292:F38-46
Miller, David S; Shaw, Joseph R; Stanton, Caitlin R et al. (2007) MRP2 and acquired tolerance to inorganic arsenic in the kidney of killifish (Fundulus heteroclitus). Toxicol Sci 97:103-10
Ballatori, Nazzareno; Henson, John H; Seward, David J et al. (2006) Retention of structural and functional polarity in cultured skate hepatocytes undergoing in vitro morphogenesis. Comp Biochem Physiol B Biochem Mol Biol 144:167-79
Aslamkhan, Amy G; Thompson, Deborah M; Perry, Jennifer L et al. (2006) The flounder organic anion transporter fOat has sequence, function, and substrate specificity similarity to both mammalian Oat1 and Oat3. Am J Physiol Regul Integr Comp Physiol 291:R1773-80
Notenboom, Sylvia; Miller, David S; Smits, P et al. (2004) Involvement of guanylyl cyclase and cGMP in the regulation of Mrp2-mediated transport in the proximal tubule. Am J Physiol Renal Physiol 287:F33-8
Karnaky Jr, Karl John; Hazen-Martin, Debra; Miller, David S (2003) The xenobiotic transporter, MRP2, in epithelia from insects, sharks, and the human breast: implications for health and disease. J Exp Zool A Comp Exp Biol 300:91-7
Notenboom, Sylvia; Miller, David S; Smits, Paul et al. (2002) Role of NO in endothelin-regulated drug transport in the renal proximal tubule. Am J Physiol Renal Physiol 282:F458-64
Miller, David S; Masereeuw, Rosalinde; Karnaky Jr, Karl J (2002) Regulation of MRP2-mediated transport in shark rectal salt gland tubules. Am J Physiol Regul Integr Comp Physiol 282:R774-81
Miller, David S (2002) Xenobiotic export pumps, endothelin signaling, and tubular nephrotoxicants--a case of molecular hijacking. J Biochem Mol Toxicol 16:121-7
Liu, J; Chen, H; Miller, D S et al. (2001) Overexpression of glutathione S-transferase II and multidrug resistance transport proteins is associated with acquired tolerance to inorganic arsenic. Mol Pharmacol 60:302-9

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