Mitochondrial genome depletion dysregulates bile acid‐ and paracetamol‐induced expression of the transporters Mdr1, Mrp1 and Mrp4 in liver cells

Abstract

BACKGROUND AND PURPOSEMitochondria are involved in the toxicity of several compounds, retro-control of gene expression and apoptosis activation. The effect of mitochondrial genome (mtDNA) depletion on changes in ABC transporter protein expression in response to bile acids and paracetamol was investigated. EXPERIMENTAL APPROACHHepa 1-6 mouse hepatoma cells with 70% decrease in 16S/18S rRNA ratio (Rho cells) were obtained by long-term treatment with ethidium bromide. KEY RESULTSSpontaneous apoptosis and reactive oxygen species (ROS) generation were decreased in Rho cells. Following glycochenodeoxycholic acid (GCDCA) or paracetamol, Rho cells generated less ROS and were more resistant to cell death. Apoptosis induced by GCDCA and Fas was also reduced. The basal expression of Mdr1 was significantly enhanced, but this was not further stimulated by GCDCA or paracetamol, as observed in wild-type (WT) cells. Basal expression of Mrp1 and Mrp4 was similar in WT and Rho cells, whereas they were up-regulated only in WT cells after GCDCA or paracetamol, along with the transcription factors Shp and Nrf2, but not Fxr or Pxr. Increased expression of Nrf2 was accompanied by its enhanced nuclear translocation. Glycoursodeoxycholic acid failed to cause any of the effects observed for GCDCA or paracetamol. CONCLUSIONS AND IMPLICATIONSThe Nrf2-mediated pathway is partly independent of ROS production. Nuclear translocation of Nrf2 is insufficient to up-regulate Mdr1, Mrp1 and Mrp4, which requires the participation of other regulatory element(s) whose activation in response to GCDCA and paracetamol is impaired in Rho cells and hence probably sensitive to ROS. AbbreviationsABC, ATP-binding cassette; CAR, constitutive androstane receptor; DCFH-DA, 2′,7′-dichlorofluorescein diacetate; FXR, farnesoid X receptor; GCDCA, glycochenodeoxycholic acid; GUDCA, glycoursodeoxycholic acid; MDR, multidrug resistance protein; MRP, multidrug resistance associated protein; NRF2, nuclear factor E2-related factor 2; PXR, pregnane X receptor; Rh123, rhodamine 123; SHP, small heterodimer partner; tBOOH, tert-butyl hydroperoxide

Farnesoid X receptor directly regulates xenobiotic detoxification genes in the long-lived Little mice

“…Interestingly, FXR was not detectable in a subclone Hepa1c1c7. This result is consistent with a recent report that very low levels of FXR mRNA were detected in Hepa1-6 cells compared with mouse livers (Perez et al, 2011). Treatment with the endogenous FXR ligand, CDCA, or the synthetic agonist, GW4064, enhanced expression and nuclear accumulation of FXR protein in Hepa1-6 cells (Fig.…”

Systems Biology Investigation to Discover Metabolic Biomarkers of Acetaminophen-Induced Hepatic Injury Using Integrated Transcriptomics and Metabolomics

“…APAP-GSH, APAP-NAC and APAP-Glu conjugates are substrates of MRP2 and MRP3 [33,34]. These results are consistent with a xenobiotic detoxification metabolism wherein the expressions of Mrp and Mdr transporters are increased to facilitate the detoxification process [35][36][37]. Thus, these findings generally indicate an adaptive response to reduce accumulation of toxic bile acids in the liver and to modulate energy expenditure as well as to accelerate the excretion of drug metabolites from the hepatocytes into the serum or urine.…”

Idiosyncratic Drug-Induced Liver Injury (IDILI): Potential Mechanisms and Predictive Assays

“…MDR1 (also known as P-glycoprotein) transports a significant amount of xenobiotics and biological compounds into the bile [88–90]. While MDR1 can be found in many tissues, it also has many substrates, making it an important efflux transporter [13].…”

“…By staining for efflux transporters, they were able to detect toxicity potential due to synergistic effects of several known idiosyncratic drugs with known effects to induce inflammation. Perez et al used flow cytometry to quantify the behavior of several efflux transporters by examining ROS production due to mitochondrial deregulation [90]. …”