Organic anion transporters (OATs) mediate the absorption, distribution, and excretion of a diverse array of environmental toxins, and clinically important drugs, including anti-HIV therapeutics, anti-tumor drugs, antibiotics, anti-hypertensives, and anti-inflammatories. OATs are mainly expressed in the kidney, liver, brain and placenta. OAT dysfunction in these organs significantly contributes to the renal, hepatic, neurological and fetal toxicity and disease. Our long-term goal is to define the molecular mechanisms underlying drug disposition through the OAT pathway. During the previous grant period, significant progress and productivity have been achieved, and the new findings from this period led to the establishment of a fine-tuned research plan and strategy in this competing renewal. We propose to test the novel hypothesis that Nedd4-2, an ubiquitin ligase, serves as a central convergence point/switch for protein kinase-regulated OAT1 activity, and therefore for transducing diverse physiological stimuli to OAT1-mediated drug transport.
Three Specific Aims are outlined.
In Specific Aim I, we will map protein kinase-specific phosphorylation sites on Nedd4-2, and examine whether phosphorylation of Nedd4-2 is the mechanism by which diverse protein kinases regulate OAT1 transport activity.
In Specific Aim II, we will identify the specific domains/amino acid residues in OAT1 and Nedd4-2, critical for the interaction between these two proteins.
In Specific Aim III, we will evaluate the physiological role of Nedd4-2 in OAT1-mediated drug transport. Combined approaches of biochemistry and molecular biology will be employed for the proposed studies in cultured cells, and in kidney slices from normal and Nedd4-2 knockout mice. Understanding the role of dynamic phosphorylation of Nedd4-2 in the regulation of OATs, a novel focus in drug transport field, will have significant impact on the future design of strategies aimed at maximizing therapeutic efficacy and minimizing toxicity, and will permit insight into the molecular, cellular, and clinical bases of renal, hepatic, neurologica and fetal toxicity and disease.

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(the same as the original) The organic anion transporter (OAT) family mediates the absorption, distribution, and excretion of a diverse array of environmental toxins, and clinically important drugs. Therefore, understanding the regulation of OATs will have significant impact on the future design of therapeutic strategies. 3

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
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Xenobiotic and Nutrient Disposition and Action Study Section (XNDA)
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Okita, Richard T
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Rutgers University
Schools of Pharmacy
New Brunswick
United States
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Wang, Haoxun; Zhang, Jinghui; You, Guofeng (2018) The mechanistic links between insulin and human organic anion transporter 4. Int J Pharm 555:165-174
Xu, Da; Zhang, Jinghui; Zhang, Qiang et al. (2017) PKC/Nedd4-2 Signaling Pathway Regulates the Cell Surface Expression of Drug Transporter hOAT1. Drug Metab Dispos 45:887-895
Wang, Haoxun; You, Guofeng (2017) SGK1/Nedd4-2 signaling pathway regulates the activity of human organic anion transporters 3. Biopharm Drug Dispos 38:449-457
Xu, Da; You, Guofeng (2017) Rethinking the regulation of l-carnitine transport in skeletal muscle cells. Focus on ""Multiple AMPK activators inhibit l-carnitine uptake in C2C12 skeletal muscle myotubes"". Am J Physiol Cell Physiol 312:C687-C688
Xu, Da; You, Guofeng (2017) Loops and layers of post-translational modifications of drug transporters. Adv Drug Deliv Rev 116:37-44
Xu, Da; Wang, Haoxun; You, Guofeng (2016) An Essential Role of Nedd4-2 in the Ubiquitination, Expression, and Function of Organic Anion Transporter-3. Mol Pharm 13:621-30
Toh, May Fern; Suh, Wonmo; Wang, Haoxun et al. (2016) Inhibitory effects of chemotherapeutics on human organic anion transporter hOAT4. Int J Biochem Mol Biol 7:11-8
Xu, Da; Wang, Haoxun; Gardner, Carol et al. (2016) The role of Nedd4-1 WW domains in binding and regulating human organic anion transporter 1. Am J Physiol Renal Physiol 311:F320-9
Wang, Haoxun; Xu, Da; Toh, May Fern et al. (2016) Serum- and glucocorticoid-inducible kinase SGK2 regulates human organic anion transporters 4 via ubiquitin ligase Nedd4-2. Biochem Pharmacol 102:120-129
Xu, Da; Wang, Haoxun; Zhang, Qiang et al. (2016) Nedd4-2 but not Nedd4-1 is critical for protein kinase C-regulated ubiquitination, expression, and transport activity of human organic anion transporter 1. Am J Physiol Renal Physiol 310:F821-31

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