NFE2L3 [Nuclear factor (erythroid-derived 2)-like 3] or NRF3, a member of the Cap'n'Collar (CNC) family, is a basic-region leucine zipper (bZIP) transcription factor that was first identified over 10 years ago. Contrary to its extensively studied homolog NFE2L2 (NRF2), the regulation and function of the NFE2L3 protein have not yet attracted as much attention. Nevertheless, several recent reports have now shed light on the possible roles of NFE2L3. Structural and biochemical studies revealed a series of domains and modifications that are critical for its cellular regulation. The control of the subcellular localization of NFE2L3 appears to be essential for understanding its role in various cellular processes. Importantly, newer studies provide fascinating insights linking NFE2L3 to differentiation, inflammation, and carcinogenesis. Here, we present an overview of the current level of knowledge of NFE2L3 transcription factor biology in humans and mice. From being the Cinderella of the CNC transcription factors for many years, NFE2L3 may now rapidly come into its own.

We analyzed the response of uterine smooth muscle cells to interleukin-1b (IL-1b). We first showed that PHM1-31 myometrial cells, our cellular model, are contractile. To determine the molecular mechanisms of uterine smooth muscle cell activation by proinflammatory cytokines, we performed genechip expression array profiling studies of PHM1-31 cells in the absence and the presence of IL-1b. In total, we identified 198 known genes whose mRNA levels are significantly modulated (O2.0-fold change) following IL-1b exposure. We confirmed the expression changes for selected genes by independent mRNA and protein analysis. The group of genes induced by IL-1b includes transcription factors and inflammatory response genes such as nuclear factor of k light polypeptide gene enhancer in B-cells (NFkB), pentraxin-related gene (PTX3), and tumor necrosis factor a-induced protein 3/A20 (TNFAIP3/A20). We also found up-regulation of chemokines like C-X-C motif ligand 3 (CXCL3) and extracellular matrix remodeling signaling molecules like tenascin C (TNC). Our data suggest that IL-1b elicits the rapid activation of a cellular network of genes particularly implicated in inflammatory response that may create a cellular environment favorable for myometrial cell contraction. Our results provide novel insights into the mechanisms of uterine smooth muscle cell regulation and possibly infection-induced preterm labor.

We have analysed the molecular and cellular regulation of the basic-leucine zipper (bZIP) transcription factor Nrf3 (NFE2-Related Factor 3). Cycloheximide studies revealed a rapid turnover of Nrf3. We showed that the proteasome inhibitor MG-132 increases Nrf3 protein levels. Furthermore, we demonstrated that Nrf3 is an N-glycosylated protein associated with the endoplasmic reticulum. Thus, our studies provide the first evidence of a post-translational modification of Nrf3.

Anaplastic large cell lymphomas (ALCLs) are frequently associated with the t(2;5)(p23;q35) translocation, leading to the expression of NPM-ALK, a fusion protein linking nucleophosmin and anaplastic lymphoma kinase, a receptor tyrosine kinase. In ALCLs, dimerization of NPM-ALK leads to constitutive autophosphorylation and activation of the kinase, necessary for NPM-ALK oncogenicity. To investigate whether NPM-ALK, like other oncogenic tyrosine kinases, can inhibit druginduced apoptosis, we permanently transfected NPM-ALK into Jurkat T-cells. As in ALCLs, NPM-ALK was expressed as a constitutively kinase-active 80 kDa protein, and could be detected by immunocytochemistry in nucleoli, nuclei and cytoplasm. Doxorubicin-induced apoptosis (assessed by cell morphology and annexin V-FITC binding) was signi®cantly inhibited in two independent NPM-ALK-expressing clones (5.2+1.8 and 7.5+0.8% apoptosis), compared to control vectortransduced cells (36+6.7%). Similar results were observed with etoposide. In contrast, Fas-induced apoptosis was not inhibited. Cytochrome c release into the cytosol was delayed in doxorubicin-, but not antiFas-treated transfectant cells, indicating that apoptosis inhibition occurred upstream of mitochondrial events. Using NPM-ALK mutants, we demonstrated that inhibition of drug-induced apoptosis: (1) requires functional kinase activity, (2) does not involve phospholipase C-g, essential for NPM-ALK-mediated mitogenicity and (3) appears to be phosphoinositide 3-kinase independent, despite a strong Akt/PKB activation observed in wild type NPM-ALK-expressing cells. These results suggest that the NPM-ALK antiapoptotic and mitogenic pathways are distinct. Oncogene (2001) 20, 7386 ± 7397.

We have previously generated mice deficient for Nfe213 (NF-E2 p45 related factor 3 or Nrf3), a member of the cap 'n' collar family of basic-leucine zipper transcription factors. To examine whether Nrf3 is involved in chemical-induced carcinogenesis, we exposed the mice to benzo- IntroductionThe polycyclic hydrocarbon benzo[a]pyrene (B[a]P) is an environmental pollutant, a major component of cigarette smoke, and a well-characterized rodent and human carcinogen. 1 For instance, B[a]P can induce lymphoma in different genetically modified mouse models. 2,3 Biotransformation of B[a]P is a requisite for its detoxification and excretion. The first step is catalyzed by cytochrome P450-dependent mono-oxygenases (phase I), and their products are subsequently coupled to endogenous metabolites (phase II). 4 However, certain reactive intermediates interact covalently with DNA to form adducts that ultimately result in mutagenicity and/or carcinogenicity. It has been reported that absence of the cap 'n' collar (CNC) factor Nrf2 renders mice more susceptible to tumorigenesis caused by B[a]P 5,6 probably because of an incapacity to detoxify the carcinogen. These data provided a link between CNC factormediated induction of phase II and antioxidant enzymes and the susceptibility to carcinogens.The CNC family includes p45 NFE2, NRF1, NRF2, NRF3, BACH1, and BACH2 proteins and can form heterodimers with small MAF proteins. We and others previously identified NRF3 as an endoplasmic reticulum-associated protein that is Asn-glycosylated. 7,8 We showed that Nrf3 gene expression is induced by butylated hydroxytoluene in the lung of mice. 9 Recently, Pepe et al showed a role for Nrf3 in smooth muscle cell differentiation. 10 We have generated mice lacking a functional Nrf3 and found that these mice do not show any obvious abnormalities under nonchallenging conditions. 11 Thus, to investigate whether the mice deficient for Nrf3 are tumor-prone, we challenged the mice with the carcinogen B[a]P. Our studies revealed a novel role for Nrf3 in the protection of mice against carcinogen-induced lymphomagenesis.