Although knowledge on acetaminophen (APAP) hepatotoxicity has advanced significantly during the last three decades, the precise mechanism of toxicity remains unknown. Even less is known about a phenomenon known as autoprotection, in which the liver adapts to sub-toxic APAP exposure, resulting in resistance to subsequent toxic APAP dosing. Our long-term goal is to understand the role of MRP (ABCC) transporters in APAP-induced hepatotoxicity. During the current funding cycle we determined that the efflux transporter Mrp4 is the most significantly induced MRP during APAP hepatotoxicity. Our data also show a strong relationship between liver Mrp4 induction and development of resistance to APAP toxicity. Therefore, the hypothesis for this competing renewal is that "Mrp4 induction is a compensatory response to drug-induced liver injury that confers resistance to subsequent toxicant challenge". To test this hypothesis, three specific research aims have been formulated. First, we will analyze the role of Mrp4 in APAP hepatotoxicity by examining the susceptibility of Mrp4-/- mice to APAP. A complementary in vitro approach is to examine the susceptibility of stably transfected immortalized human hepatocytes overexpresing Mrp4 cells (hMRP4-HC04) to APAP cytotoxicity. Then, we will determine the functional consequences of Mrp4 induction using metabolomic approaches to identify endogenous molecules transported by MRP4 with paracrine functions promoting heightened cellular defenses and compensatory cell proliferation. Lastly, transcriptional regulation of MRP4 gene expression in response to oxidative stress will be examined using molecular biological approaches and bioinformatics. Characterization of the transcription activity of mouse and human Mrp4/MRP4 gene promoter and its proximal regions will be carried out. Additional investigations will determine the effects of two transcription factors (NFR1 and HES-1) in MRP4 gene expression. Altered liver MRP4 expression may be essential for cell survival during periods of recovery and regeneration from drug-induced liver injury. This adaptation may mediate more efficient hepatobiliary excretion of cytotoxic intermediates and/or enhance the export of endogenous substrates for paracrine signaling to adjacent hepatocytes and non-parenchymal cells to promote survival and tissue repair. An increased knowledge of MRP4 regulation is expected to lead to better treatments of specific liver disorders and reduce the risk of drug liver injury. !

Public Health Relevance

Drug-induced liver injury (DILI) is a very serious human health problem. By increasing the knowledge on how hepatic drug transporters are regulated during DILI and their function , new therapeutic approaches for treatment and recovery from liver diseases induced by drugs may be designed. The research proposed in this application is significant because it is expected to provide this knowledge. The goal of this application is to better define the role of MRP4 during drug-induced acute hepatotoxicity and to further characterize the transcriptional regulation and function of MRP4 during oxidative stress. The study of this compensatory response to APAP exposure is well within the mission and goals of the NIDDK Drug Induced Liver Injury Network (DILIN).

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK069557-08
Application #
8490356
Study Section
Xenobiotic and Nutrient Disposition and Action Study Section (XNDA)
Program Officer
Serrano, Jose
Project Start
2004-12-01
Project End
2014-06-30
Budget Start
2013-07-01
Budget End
2014-06-30
Support Year
8
Fiscal Year
2013
Total Cost
$298,788
Indirect Cost
$100,553
Name
University of Connecticut
Department
Pharmacology
Type
Schools of Pharmacy
DUNS #
614209054
City
Storrs-Mansfield
State
CT
Country
United States
Zip Code
06269
Rudraiah, Swetha; Moscovitz, Jamie E; Donepudi, Ajay C et al. (2014) Differential Fmo3 gene expression in various liver injury models involving hepatic oxidative stress in mice. Toxicology 325:85-95
Rohrer, Philip R; Rudraiah, Swetha; Goedken, Michael J et al. (2014) Is nuclear factor erythroid 2-related factor 2 responsible for sex differences in susceptibility to acetaminophen-induced hepatotoxicity in mice? Drug Metab Dispos 42:1663-74
Rudraiah, Swetha; Rohrer, Philip R; Gurevich, Igor et al. (2014) Tolerance to acetaminophen hepatotoxicity in the mouse model of autoprotection is associated with induction of flavin-containing monooxygenase-3 (FMO3) in hepatocytes. Toxicol Sci 141:263-77
O'Connor, Meeghan A; Koza-Taylor, Petra; Campion, Sarah N et al. (2014) Analysis of changes in hepatic gene expression in a murine model of tolerance to acetaminophen hepatotoxicity (autoprotection). Toxicol Appl Pharmacol 274:156-67
Gu, Xinsheng; Manautou, Jose E (2012) Molecular mechanisms underlying chemical liver injury. Expert Rev Mol Med 14:e4
Gu, Xinsheng; Manautou, Jose E (2010) Regulation of hepatic ABCC transporters by xenobiotics and in disease states. Drug Metab Rev 42:482-538
Campion, Sarah N; Tatis-Rios, Cristina; Augustine, Lisa M et al. (2009) Effect of allyl alcohol on hepatic transporter expression: zonal patterns of expression and role of Kupffer cell function. Toxicol Appl Pharmacol 236:49-58
Aleksunes, Lauren M; Augustine, Lisa M; Scheffer, George L et al. (2008) Renal xenobiotic transporters are differentially expressed in mice following cisplatin treatment. Toxicology 250:82-8
Aleksunes, Lauren M; Campion, Sarah N; Goedken, Michael J et al. (2008) Acquired resistance to acetaminophen hepatotoxicity is associated with induction of multidrug resistance-associated protein 4 (Mrp4) in proliferating hepatocytes. Toxicol Sci 104:261-73
Campion, Sarah N; Johnson, Rachel; Aleksunes, Lauren M et al. (2008) Hepatic Mrp4 induction following acetaminophen exposure is dependent on Kupffer cell function. Am J Physiol Gastrointest Liver Physiol 295:G294-304

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