Nrf1 and Nrf2 regulate rat glutamate-cysteine ligase catalytic subunit transcription indirectly via NF-kappaB and AP-1.
Glutamate-cysteine ligase catalytic subunit (GCLC) is regulated transcriptionally by Nrf1 and Nrf2. tert-Butylhydroquinone (TBH) induces human GCLC via Nrf2-mediated trans activation of the antioxidant-responsive element (ARE). Interestingly, TBH also induces rat GCLC, but the rat GCLC promoter lacks ARE. This study examined the role of Nrf1 and Nrf2 in the transcriptional regulation of rat GCLC. The baseline and TBH-mediated increase in GCLC mRNA levels and rat GCLC promoter activity were lower in Nrf1 and Nrf2 null (F1 and F2) fibroblasts than in wild-type cells. The basal protein and mRNA levels and nuclear binding activities of c-Jun, c-Fos, p50, and p65 were lower in F1 and F2 cells and exhibited a blunted response to TBH. Lower c-Jun and p65 expression also occurs in Nrf2 null livers. Levels of other AP-1 and NF-kappaB family members were either unaffected (i.e., JunB) or increased (i.e., Fra-1). Overexpression of Nrf1 and Nrf2 in respective cells restored the rat GCLC promoter activity and response to TBH but not if the AP-1 and NF-kappaB binding sites were mutated. Fra-1 overexpression lowered endogenous GCLC expression and rat GCLC promoter activity, while Fra-1 antisense had the opposite effects. In conclusion, Nrf1 and Nrf2 regulate rat GCLC promoter by modulating the expression of key AP-1 and NF-kappaB family members.
Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, Keck School of Medicine USC, Los Angeles, California 90033, USA.
Heping
H
Yang
Nathaniel
N
Magilnick
Candy
C
Lee
Denise
D
Kalmaz
Xiaopeng
X
Ou
Jefferson Y
JY
Chan
Shelly C
SC
Lu
D000818:Animals; D001665:Binding Sites; D020134:Catalytic Domain / Q000235:genetics; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D005786:Gene Expression Regulation; D005721:Glutamate-Cysteine Ligase / Q000235:genetics*; D006873:Hydroquinones / Q000494:pharmacology; D008099:Liver / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D051265:NF-E2-Related Factor 1; D051267:NF-E2-Related Factor 2; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D051266:Nuclear Respiratory Factor 1; D051264:Nuclear Respiratory Factors; D011401:Promoter Regions, Genetic; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D051381:Rats; D015534:Trans-Activators / Q000235:genetics / Q000502:physiology*; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D000099169:Fos-Related Antigen 1
D004268:DNA-Binding Proteins; D005721:Glutamate-Cysteine Ligase; D006873:Hydroquinones; D051265:NF-E2-Related Factor 1; D051267:NF-E2-Related Factor 2; D016328:NF-kappa B; D051266:Nuclear Respiratory Factor 1; D051264:Nuclear Respiratory Factors; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D015534:Trans-Activators; D018808:Transcription Factor AP-1; D000099169:Fos-Related Antigen 1; C495632:Nfe2l1 protein, rat; C495636:Nfe2l2 protein, mouse; C495637:Nfe2l2 protein, rat; C495634:Nrf1 protein, mouse; C018855:2-tert-butylhydroquinone