Disease relevance of Nfe2

• Dependence of globin gene expression in mouse erythroleukemia cells on the NF-E2 heterodimer [1].
• Results of DNase I hypersensitivity mapping and in vivo footprinting assays showed no detectable chromatin alterations in beta-LCR HS-2 due to loss of NF-E2 [1].
• While p45 gene knockout mice exhibit thrombocytopenia due to abnormal terminal differentiation of megakaryocytes, and the mutant mice die of massive bleeding within a week after birth, anemia is not apparent in these animals [2].
• Unexpectedly, NF-E2-/- mice lack circulating platelets and die of hemorrhage; their megakaryocytes show no cytoplasmic platelet formation [3].
• Although neonates exhibited severe anemia and dysmorphic red-cell changes, probably compounded by concomitant bleeding, surviving adults exhibited only mild changes consistent with a small decrease in the hemoglobin content per cell. p45 NF-E2-null mice responded to anemia with compensatory reticulocytosis and splenomegaly [4].

High impact information on Nfe2

• Thus, as an essential factor for megakaryocyte maturation and platelet production, NF-E2 must regulate critical target genes independent of the action of thrombopoietin [3].
• Whereas homodimers of the small Maf proteins act as negative regulators, heterodimers composed of Maf and p45 support active transcription in vivo [5].
• Regulation of transcription by dimerization of erythroid factor NF-E2 p45 with small Maf proteins [5].
• The mk allele carries a missense mutation that causes substitution of valine by alanine at amino acid 173 of the p45 NF-E2 protein [6].
• Expression of p45 NF-E2 messenger RNA was detected in erythroid tissues of normal mice and in the duodenum of normal and severely anaemic beta-thalassaemic (Hbbd-th3/Hbbd-th3) mice [6].

Chemical compound and disease context of Nfe2

• We show here that dimethyl sulfoxide treatment of wild-type murine erythroleukemia cells, but not a mutant clone of dimethyl sulfoxide-resistant cells, increases NF-E2 activity significantly, which involves both up-regulation of DNA binding and transactivation activities [7].
• These findings indicate that induction of NF-E2 activity is essential for erythroid differentiation of murine erythroleukemia cells, and serine/threonine phosphorylation may be involved in this process [7].
• NF-E2p18/mafK is required in DMSO-induced differentiation of Friend erythroleukemia cells by enhancing NF-E2 activity [8].

Biological context of Nfe2

• These findings suggest that the beta-globin gene locus exists in a constitutively open chromatin conformation before terminal differentiation, and we speculate that recruitment of NF-E2 complex to the LCR and active promoters may be a rate-limiting step in the activation of beta-globin gene expression [9].
• This differentiation-coupled recruitment of NF-E2 complex correlates with a greater than 100-fold increase in beta-major globin transcription, but is not associated with a significant change in locus-wide histone H3 acetylation [9].
• NF-E2 binding sites, located in distant regulatory sequences, may be important for high level alpha- and beta-globin gene expression [10].
• In addition, no evidence was found for reciprocal upregulation of NF-E2 or Nrf-2 protein in fetal liver cells deficient for either factor [10].
• Cotransfection assays using HDC-luciferase reporter and p45 and/or mafK expression constructs showed that NF-E2 affects the transactivation of HDC gene [11].

Anatomical context of Nfe2

• This subunit of NF-E2 is specifically expressed in haematopoietic progenitor cells and differentiated cells of the erythroid, megakaryocyte and mast cell lineages [6].
• Reduced levels of both alpha- and beta-globin were associated with the lower levels of NF-E2 activity in this cell line [1].
• Fetal liver cells deficient for both NF-E2 and Nrf-2 expressed normal levels of alpha- and beta-globin [10].
• Northern blotting has shown that mouse small intestine contains relatively large amounts of the nuclear factor-E2 p45-related factor (Nrf) 2 transcription factor but relatively little Nrf1 [12].
• These results suggest that NF-E2 is also an important transcription factor in mast cell differentiation [11].

Associations of Nfe2 with chemical compounds

• The Cap'n'Collar basic leucine zipper transcription factor Nrf2 (NF-E2 p45-related factor 2) controls both constitutive and inducible expression of intestinal detoxification and glutathione biosynthetic enzymes [12].
• Domain analysis revealed an activation domain in the NH2-terminal region of p45 and a suppression domain in the basic region-leucine zipper of MafK [7].
• Next, we removed the neo gene by Cre-mediated recombination, leaving a single LoxP site in place of the AP1/NFE2 sites [13].
• Transcription of the p45 target genes was down-regulated and we indeed found that BACH1 binds to the thromboxane synthase gene, one of the target genes for p45 in megakaryocytes [14].
• Other proline-rich sequences were dispensable, indicating that proline content per se does not determine NF-E2 activity [15].

Regulatory relationships of Nfe2

• Caspase-12 is the most down-regulated gene we identified in NF-E2(-/-) megakaryocytes [16].
• Our findings demonstrate marked induction of NF-E2 mRNA in control megakaryocytes in response to Mpl ligand, but no NF-E2 increase in transgenic cells, potentially explaining the lack of platelet increase in these transgenic mice [17].
• In contrast to MEL cells, CB3 cells are null for p45 and thus express only extremely low levels of adult globin transcripts upon induction by agents promoting erythroid differentiation [18].

Other interactions of Nfe2

• cDNA cloning of murine Nrf 2 gene, coding for a p45 NF-E2 related transcription factor [19].
• A role for Rab27b in NF-E2-dependent pathways of platelet formation [20].
• The NO-releasing agents and cGMP analogues largely prevented HMBA-induced increases in DNA binding of NF-E2, whereas DNA binding of GATA-1 and SP-1 was not affected [21].
• Contiguous arrangement of p45 NFE2, HnRNP A1, and HP1 alpha on mouse chromosome 15 and human chromosome 12: evidence for suppression of these genes due to retroviral integration within the Fli-2 locus [22].
• Transgenic megakaryocytes treated with Mpl ligand display a limited increase in NF-E2 [17].
• Transactivation studies and chromatin immunoprecipitation implicate Lims1 as a direct target of NF-E2 regulation [23].

Analytical, diagnostic and therapeutic context of Nfe2

• Chromatin immunoprecipitation demonstrates recruitment of NF-E2 to the putative Rab27B promoter [20].
• Using immunofluorescence microscopy, we show that the two NF-E2 subunits occupy distinct nuclear compartments in uninduced MEL cells; the smaller subunit NF-E2p18 is found primarily in the centromeric heterochromatin compartment, whereas the larger subunit NF-E2p45 occupies the euchromatin compartment [24].
• Despite impressive splenomegaly at baseline, mice lacking p45 NF-E2 survived splenectomy, which resulted in increased reticulocyte numbers [25].
• Using transfection of promoter/reporter plasmids in human tissue culture cell lines, in vitro DNase I footprinting analyses, and gel mobility shift assays, an alpha-spectrin gene erythroid promoter with binding sites for GATA-1- and NF-E2-related proteins was identified [26].
• We also studied the effects of TPO on expression of GpIIb and NF-E2 transcripts by RT-PCR and on proplatelet formation [27].

References