These authors contributed equally to this work.
Article first published online: 6 SEP 2011
Copyright © 2011 American Association for the Study of Liver Diseases
Volume 54, Issue 4, pages 1322–1332, October 2011
How to Cite
Ahmed, M. M.E., Wang, T., Luo, Y., Ye, S., Wu, Q., Guo, Z., Roebuck, B. D., Sutter, T. R. and Yang, J. Y. (2011), Aldo-keto reductase-7A protects liver cells and tissues from acetaminophen-induced oxidative stress and hepatotoxicity. Hepatology, 54: 1322–1332. doi: 10.1002/hep.24493
Potential conflict of interest: Nothing to report.
This work was supported, in part, by grants from the National Science Foundation of China (#30970649), the 973 Program of China (#2009CB941601), the Fujian Provincial Department of Science and Technology (#2010L0002), and the Science Planning Program of Fujian Province (#2010J1008).
- Issue published online: 27 SEP 2011
- Article first published online: 6 SEP 2011
- Accepted manuscript online: 17 JUN 2011 02:12PM EST
- Manuscript Accepted: 1 JUN 2011
- Manuscript Received: 28 DEC 2010
Aldo-keto reductase-7A (AKR7A) is an enzyme important for bioactivation and biodetoxification. Previous studies suggested that Akr7a might be transcriptionally regulated by oxidative stress-responsive transcription factor nuclear factor erythroid 2 p45-related factor 2 (Nrf2), a protein highly responsive to acetaminophen (APAP) or its intermediate metabolite, N-acetyl-p-benzoquinoneimine (NAPQI). This study was, therefore, carried out to investigate whether Akr7a is involved in the protection against APAP-induced oxidative stress and hepatotoxicity. We found that in response to APAP or NAPQI exposure, Akr7a3 mRNA and protein were significantly up-regulated in vitro in human HepG2 and LO2 cells. Similarly, strong induction was observed for Akr7a5 in mouse AML12 hepatocytes exposed to APAP. In vivo in wild-type rats, significant up-regulation of hepatic AKR7A1 protein was observed after administration of APAP. On the other hand, depletion of Nrf2 reduced the expression of Akr7a3, suggesting that Nrf2, indeed, contributes significantly to the induction of Akr7a. Moreover, loss of cell viability in Nrf2-depleted cells was significantly rescued by coexpression of AKR7A3. Furthermore, increased AKR7A3 in HepG2 cells was associated with the up-regulation of oxidative stress-related enzymes to enhance cellular antioxidant defense, which appeared to contribute significantly to protection against APAP-induced toxicity. In a line of transgenic rats overexpressing AKR7A1, increased AKR7A1 stimulated the expression of Nrf2 and other Nrf2-regulated genes, but did not better protect rats from APAP insults. In contrast, depletion of Akr7a5 in vitro in cultured AML12 cells or depletion of Akr7a1 in vivo in rat liver greatly increased APAP-induced hepatotoxicity. Conclusion: AKR7A proteins are significantly up-regulated in response to APAP/NAPQI exposure to contribute significantly to protection against APAP-induced hepatotoxicity. AKR7A mediates this protection, in part, through enhancing hepatocellular antioxidant defense. (HEPATOLOGY 2011;)