At physiological pH, many drugs (eg. penicillins, NSAIDs, methotrexate, thiazides) exist as organic anions and are eliminated via the kidney proximal tubule through multispecific renal organic anion transporters (especially OAT1 and OAT3). Apart from their general relevance to renal drug elimination, OATs are of current interest because they mediate nephrotoxicity of the antivirals cidofovir and adefovir, drugs which could be used in the event of a smallpox epidemic. Due to their toxicity, treatment and prophylaxis of many individuals with these drugs (as might be required in an epidemic) is likely to result in significant morbidity. Here, we hypothesize that altered function and expression of OAT1 and OAT3 due to coding and noncodinq region SNPs are key determinants of individual variation in renal drug elimination and nephrotoxicitv from drugs like cidofovir. The Pi's lab is in an ideal position to address this question as it was the first to identify the prototypical member of this family (originally called NKT, later termed OAT1), as well as several other SLC22 family members, and the first to describe a knockout of an OAT (OAT3). As part of this REVISED proposal, we aim to: 1) identify human SNPs in OAT1 and OATS in ethnically diverse samples; 2) employ two independent computational approaches (structural modeling and phylogenetic footprinting) to prioritize SNPs in terms of likelihood of functional effects on drug transport and OAT gene expression; 3) analyze the effects of coding region SNPs in order of in silica priority on in vitro drug transport (eg. using Xenopus oocyte and COS-7 expression systems) and the effects of noncoding SNPs on OAT gene expression (eg.by performing transfections of promoter constructs). We provide evidence of our ability to do all these studies and also have well-established (published) collaborations with individuals who have particular expertise in techniques that will support the project. We have done our best to address all the concerns of the previous review. Considerable new preliminary data, including major refinements in the computational model, are presented. Since a large, healthy, phenotyped group of patients treated with nephrotoxic drugs like cidofovir does not exist, we argue that this computational strategy of prioritizing OAT SNPs, followed by in vitro analysis of function and expression, is a logical approach for understanding the impact of OAT1 and OAT3 polymorphisms on handling of drugs and their toxicity. Ultimately, this work should provide the basis of a useful strategy to diminish renal failure in humans treated with nephrotoxic drugs.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
1R01AI057695-01A2
Application #
6920979
Study Section
Cellular and Molecular Biology of the Kidney Study Section (CMBK)
Program Officer
Greenstone, Heather Lea
Project Start
2005-07-01
Project End
2010-03-31
Budget Start
2005-07-01
Budget End
2006-03-31
Support Year
1
Fiscal Year
2005
Total Cost
$294,525
Indirect Cost
Name
University of California San Diego
Department
Pediatrics
Type
Schools of Medicine
DUNS #
804355790
City
La Jolla
State
CA
Country
United States
Zip Code
92093
Nagle, Megha A; Truong, David M; Dnyanmote, Ankur V et al. (2011) Analysis of three-dimensional systems for developing and mature kidneys clarifies the role of OAT1 and OAT3 in antiviral handling. J Biol Chem 286:243-51
Wu, Wei; Dnyanmote, Ankur V; Nigam, Sanjay K (2011) Remote communication through solute carriers and ATP binding cassette drug transporter pathways: an update on the remote sensing and signaling hypothesis. Mol Pharmacol 79:795-805
Tsigelny, Igor F; Kovalskyy, Dmytro; Kouznetsova, Valentina L et al. (2011) Conformational changes of the multispecific transporter organic anion transporter 1 (OAT1/SLC22A6) suggests a molecular mechanism for initial stages of drug and metabolite transport. Cell Biochem Biophys 61:251-9
Wikoff, William R; Nagle, Megha A; Kouznetsova, Valentina L et al. (2011) Untargeted metabolomics identifies enterobiome metabolites and putative uremic toxins as substrates of organic anion transporter 1 (Oat1). J Proteome Res 10:2842-51
Ahn, Sun-Young; Eraly, Satish A; Tsigelny, Igor et al. (2009) Interaction of organic cations with organic anion transporters. J Biol Chem 284:31422-30
Ahn, Sun-Young; Nigam, Sanjay K (2009) Toward a systems level understanding of organic anion and other multispecific drug transporters: a remote sensing and signaling hypothesis. Mol Pharmacol 76:481-90
Wu, Wei; Baker, Michael E; Eraly, Satish A et al. (2009) Analysis of a large cluster of SLC22 transporter genes, including novel USTs, reveals species-specific amplification of subsets of family members. Physiol Genomics 38:116-24
Eraly, Satish A; Vallon, Volker; Rieg, Timo et al. (2008) Multiple organic anion transporters contribute to net renal excretion of uric acid. Physiol Genomics 33:180-92
Truong, David M; Kaler, Gregory; Khandelwal, Akash et al. (2008) Multi-level analysis of organic anion transporters 1, 3, and 6 reveals major differences in structural determinants of antiviral discrimination. J Biol Chem 283:8654-63
Vallon, Volker; Eraly, Satish A; Wikoff, William R et al. (2008) Organic anion transporter 3 contributes to the regulation of blood pressure. J Am Soc Nephrol 19:1732-40

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