| First Author | Gong P | Year | 2006 |
| Journal | J Biol Chem | Volume | 281 |
| Issue | 21 | Pages | 14573-9 |
| PubMed ID | 16551616 | Mgi Jnum | J:113505 |
| Mgi Id | MGI:3686850 | Doi | 10.1074/jbc.M600613200 |
| Citation | Gong P, et al. (2006) Transcription factor Nrf2 protects HepG2 cells against CYP2E1 plus arachidonic acid-dependent toxicity. J Biol Chem 281(21):14573-9 |
| abstractText | Nrf2 is a transcription factor that regulates important antioxidant and phase II detoxification genes. Arachidonic acid (AA) causes CYP2E1-dependent toxicity in HepG2 cells. The ability of Nrf2 to protect against CYP2E1-dependent AA toxicity and its possible mechanism were evaluated. AA activates Nrf2 in CYP2E1-expressing HepG2 cells (E47 cells), increasing Nrf2 protein and mRNA levels, Nrf2 nuclear translocation, and Nrf2-ARE binding activity. These increases in Nrf2 are associated with elevated expression of Nrf2-regulated antioxidant genes. Overexpression of Nrf2 by transient transfection of plasmid Nrf2 confers resistance of E47 cells against AA toxicity. Blocking Nrf2 with small interfering RNA (siRNA)-Nrf2 potentiates the CYP2E1-dependent AA toxicity. This enhanced toxicity is accompanied by decreases of cellular GSH levels and increases in production of reactive oxygen species and lipid peroxidation. There is also a potentiation of mitochondrial damage in the presence of siRNA-Nrf2. The protective effects of Nrf2 against CYP2E1-dependent toxicity can be blocked by l-buthionine-(S,R)-sulfoximine, a specific inhibitor of glutamate-cysteine ligase, which is a rate-limiting enzyme in the synthesis of GSH and is regulated by Nrf2. Elevation of GSH by supplementing with glutathione ethyl ester can partially reverse the enhanced AA toxicity by siRNA-Nrf2. Moreover, in contrast to AA, l-buthionine-(S,R)-sulfoximine toxicity is not prevented by plasmid Nrf2 probably because protective GSH cannot be synthesized. Together, these results suggest that Nrf2, through up-regulation of glutamate-cysteine ligase and increase of GSH levels, protects against CYP2E1-dependent AA toxicity. |
