Renal elimination of anionic drugs, xenobiotics and toxins are necessary for the survival of mammalian species. This process is mediated by vectorial transport from blood into the urine through the cooperative function of specific transporters in the basolateral and apical membranes of the proximal tubule epithelium. The first step of this process is the extraction of organic anions from the peritubular blood plasma into proximal tubule cells through, in part, the organic anion transporter (OAT) pathway. As a result, OAT pathway is one of the major sites for body drug clearance/detoxification but it is also the site for drug-drug interaction and drug-induced nephrotoxicity. To maximize therapeutic efficacy and minimize toxicity, the transporter structure-function relationships, including drug/inhibitor binding sites, and the regulation of transport mechanisms must be defined. The overall objective of this application is to define the molecular mechanisms underlying drug elimination through the OAT pathway. We have recently isolated a cDNA from mouse kidney which encodes the first member of the OAT family. We have shown that OAT function is down-regulated by two distinct mechanisms: a) activation of PKC (which does not phosphorylate OAT), and b) serine-phosphorylation of OAT by an unknown kinase.
Two specific aims (SA) are therefore proposed. In SA-1, we will identify the functional determinants of OAT through a combination of biochemical, biophysical and genetic engineering approaches. In SA-2, we will identify the short-term regulatory mechanisms of OAT function. We will first identify the site(s) of serine phosphorylation and the kinases which phosphorylate OAT through a combination of mass spectra and site-directed mutagenesis. We will then explore the mechanisms by which kinases/phosphorylationj influence OAT function. The knowledge gained from these studies will be invaluable toward the rational design of novel drugs and inhibitors to optimize drug therapy while avoiding unwanted drug interactions. These studies should also provide fundamental important mechanistic information applicable to the whole family of OAT-like transporters. Ultimately, this work should permit insight into the mechanism and regulation of organic anion transport in normal kidney and in various acquired and inheritable disorders.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK060034-04
Application #
6647684
Study Section
Pharmacology A Study Section (PHRA)
Program Officer
Ketchum, Christian J
Project Start
2001-08-01
Project End
2006-05-31
Budget Start
2003-08-01
Budget End
2004-05-31
Support Year
4
Fiscal Year
2003
Total Cost
$272,125
Indirect Cost
Name
Rutgers University
Department
Pharmacology
Type
Schools of Pharmacy
DUNS #
001912864
City
New Brunswick
State
NJ
Country
United States
Zip Code
08901
Li, Shanshan; Zhang, Qiang; You, Guofeng (2013) Three ubiquitination sites of organic anion transporter-1 synergistically mediate protein kinase C-dependent endocytosis of the transporter. Mol Pharmacol 84:139-46
Zhang, Qiang; Li, Shanshan; Patterson, Cam et al. (2013) Lysine 48-linked polyubiquitination of organic anion transporter-1 is essential for its protein kinase C-regulated endocytosis. Mol Pharmacol 83:217-24
Zhang, Qiang; Suh, Wonmo; Pan, Zui et al. (2012) Short-term and long-term effects of protein kinase C on the trafficking and stability of human organic anion transporter 3. Int J Biochem Mol Biol 3:242-9
Duan, Peng; Li, Shanshan; Ai, Ni et al. (2012) Potent inhibitors of human organic anion transporters 1 and 3 from clinical drug libraries: discovery and molecular characterization. Mol Pharm 9:3340-6
Duan, Peng; Li, Shanshan; You, Guofeng (2012) Regulation of human organic anion transporter 4 by parathyroid hormone-related protein and protein kinase A. Int J Biochem Mol Biol 3:322-7
Duan, Peng; Li, Shanshan; You, Guofeng (2011) Transmembrane peptide as potent inhibitor of oligomerization and function of human organic anion transporter 1. Mol Pharmacol 79:569-74
Duan, Peng; Wu, Jinwei; You, Guofeng (2011) Mutational analysis of the role of GXXXG motif in the function of human organic anion transporter 1 (hOAT1). Int J Biochem Mol Biol 2:1-7
Zhang, Qiang; Wu, Jinwei; Pan, Zui et al. (2011) The Role of Dileucine in the Expression and Function of Human Organic Anion Transporter 1 (hOAT1). Int J Biochem Mol Biol 2:31-38
Zhang, Qiang; Pan, Zui; You, Guofeng (2010) Regulation of human organic anion transporter 4 by protein kinase C and NHERF-1: altering the endocytosis of the transporter. Pharm Res 27:589-96
Duan, Peng; Li, Shanshan; You, Guofeng (2010) Angiotensin II inhibits activity of human organic anion transporter 3 through activation of protein kinase Calpha: accelerating endocytosis of the transporter. Eur J Pharmacol 627:49-55

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