| First Author | Zhang Y | Year | 2014 |
| Journal | PLoS One | Volume | 9 |
| Issue | 10 | Pages | e109159 |
| PubMed ID | 25290918 | Mgi Jnum | J:223104 |
| Mgi Id | MGI:5647964 | Doi | 10.1371/journal.pone.0109159 |
| Citation | Zhang Y, et al. (2014) The C-terminal domain of Nrf1 negatively regulates the full-length CNC-bZIP factor and its shorter isoform LCR-F1/Nrf1beta; both are also inhibited by the small dominant-negative Nrf1gamma/delta isoforms that down-regulate ARE-battery gene expression. PLoS One 9(10):e109159 |
| abstractText | The C-terminal domain (CTD, aa 686-741) of nuclear factor-erythroid 2 p45-related factor 1 (Nrf1) shares 53% amino acid sequence identity with the equivalent Neh3 domain of Nrf2, a homologous transcription factor. The Neh3 positively regulates Nrf2, but whether the Neh3-like (Neh3L) CTD of Nrf1 has a similar role in regulating Nrf1-target gene expression is unknown. Herein, we report that CTD negatively regulates the full-length Nrf1 (i.e. 120-kDa glycoprotein and 95-kDa deglycoprotein) and its shorter isoform LCR-F1/Nrf1beta (55-kDa). Attachment of its CTD-adjoining 112-aa to the C-terminus of Nrf2 yields the chimaeric Nrf2-C112Nrf1 factor with a markedly decreased activity. Live-cell imaging of GFP-CTD reveals that the extra-nuclear portion of the fusion protein is allowed to associate with the endoplasmic reticulum (ER) membrane through the amphipathic Neh3L region of Nrf1 and its basic c-tail. Thus removal of either the entire CTD or the essential Neh3L portion within CTD from Nrf1, LCR-F1/Nrf1beta and Nrf2-C112Nrf1, results in an increase in their transcriptional ability to regulate antioxidant response element (ARE)-driven reporter genes. Further examinations unravel that two smaller isoforms, 36-kDa Nrf1gamma and 25-kDa Nrf1delta, act as dominant-negative inhibitors to compete against Nrf1, LCR-F1/Nrf1beta and Nrf2. Relative to Nrf1, LCR-F1/Nrf1beta is a weak activator, that is positively regulated by its Asn/Ser/Thr-rich (NST) domain and acidic domain 2 (AD2). Like AD1 of Nrf1, both AD2 and NST domain of LCR-F1/Nrf1beta fused within two different chimaeric contexts to yield Gal4D:Nrf1beta607 and Nrf1beta:C270Nrf2, positively regulate their transactivation activity of cognate Gal4- and Nrf2-target reporter genes. More importantly, differential expression of endogenous ARE-battery genes is attributable to up-regulation by Nrf1 and LCR-F1/Nrf1beta and down-regulation by Nrf1gamma and Nrf1delta. |
