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. !
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).
|Flores, Katiria; Manautou, José E; Renfro, J Larry (2017) Gender-specific expression of ATP-binding cassette (Abc) transporters and cytoprotective genes in mouse choroid plexus. Toxicology 386:84-92|
|Scialis, Renato J; Manautou, José E (2016) Elucidation of the Mechanisms through Which the Reactive Metabolite Diclofenac Acyl Glucuronide Can Mediate Toxicity. J Pharmacol Exp Ther 357:167-76|
|Rigalli, Juan Pablo; Perdomo, Virginia Gabriela; Ciriaci, Nadia et al. (2016) The trypanocidal benznidazole promotes adaptive response to oxidative injury: Involvement of the nuclear factor-erythroid 2-related factor-2 (Nrf2) and multidrug resistance associated protein 2 (MRP2). Toxicol Appl Pharmacol 304:90-8|
|Ghanem, Carolina I; Pérez, María J; Manautou, José E et al. (2016) Acetaminophen from liver to brain: New insights into drug pharmacological action and toxicity. Pharmacol Res 109:119-31|
|Ferreira, Daniel W; Goedken, Michael J; Rommelaere, Samuel et al. (2016) Enhanced hepatotoxicity by acetaminophen in Vanin-1 knockout mice is associated with deficient proliferative and immune responses. Biochim Biophys Acta 1862:662-669|
|Rudraiah, Swetha; Gu, Xinsheng; Hines, Ronald N et al. (2016) Oxidative stress-responsive transcription factor NRF2 is not indispensable for the human hepatic Flavin-containing monooxygenase-3 (FMO3) gene expression in HepG2 cells. Toxicol In Vitro 31:54-9|
|Scialis, Renato J; Csanaky, Iván L; Goedken, Michael J et al. (2015) Multidrug Resistance-Associated Protein 3 Plays an Important Role in Protection against Acute Toxicity of Diclofenac. Drug Metab Dispos 43:944-50|
|Njayou, Frédéric Nico; Amougou, Atsama Marie; Fouemene Tsayem, Romeo et al. (2015) Antioxidant fractions of Khaya grandifoliola C.DC. and Entada africana Guill. et Perr. induce nuclear translocation of Nrf2 in HC-04 cells. Cell Stress Chaperones 20:991-1000|
|Ghanem, Carolina I; Rudraiah, Swetha; Bataille, Amy M et al. (2015) Role of nuclear factor-erythroid 2-related factor 2 (Nrf2) in the transcriptional regulation of brain ABC transporters during acute acetaminophen (APAP) intoxication in mice. Biochem Pharmacol 94:203-11|
|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|
Showing the most recent 10 out of 29 publications