title: Functional and placental expression analysis of the human NRF3 transcription factor.
abstract: Members of the Maf protooncogene and cap'n' collar families of basic-leucine zipper transcription factors play important roles in development, differentiation, oncogenesis, and stress signaling. In this study, we performed an in vivo protein-protein interaction screen to search for novel partners of the small Maf proteins. Using full-length human MAFG protein as bait, we identified the human basic-leucine zipper protein NRF3 [NF-E2 (nuclear factor erythroid 2)-related factor 3] as an interaction partner. Transfection studies confirmed that NRF3 is able to dimerize with MAFG. The resulting NRF3/MAFG heterodimer recognizes nuclear factor-erythroid 2/Maf recognition element-type DNA-binding motifs. Functional analysis revealed the presence of a strong transcriptional activation domain in the center region of the NRF3 protein. We found that NRF3 transcripts are present in placental chorionic villi from at least week 12 of gestation on through term. In particular, NRF3 is highly expressed in primary placental cytotrophoblasts, but not in placental fibroblasts. The human choriocarcinoma cell lines BeWo and JAR, derived from trophoblastic tumors of the placenta, also strongly express NRF3 transcripts. We generated a NRF3-specific antiserum and identified NRF3 protein in placental choriocarcinoma cells. Furthermore, we showed that NRF3 transcript and protein levels are induced by TNF-alpha in JAR cells. Our functional studies suggest that human NRF3 is a potent transcriptional activator. Finally, our expression and induction analyses hint at a possible role of Nrf3 in placental gene expression and development.
authors.affiliation: Lady Davis Institute for Medical Research, University of Montréal, 3755 Côte-Sainte-Catherine Road, Montréal, Québec, Canada H3T 1E2.
authors.forename: Benoît
authors.initials: B
authors.lastname: Chénais
authors.forename: Anna
authors.initials: A
authors.lastname: Derjuga
authors.forename: Wael
authors.initials: W
authors.lastname: Massrieh
authors.forename: Kristy
authors.initials: K
authors.lastname: Red-Horse
authors.forename: Valerie
authors.initials: V
authors.lastname: Bellingard
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Fisher
authors.forename: Volker
authors.initials: V
authors.lastname: Blank
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D050976:Basic-Leucine Zipper Transcription Factors; D002478:Cells, Cultured; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism; D019281:Dimerization; D020869:Gene Expression Profiling; D006801:Humans; D051259:MafG Transcription Factor; D008969:Molecular Sequence Data; D009928:Organ Specificity; D010920:Placenta / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins / Q000378:metabolism; D020218:Response Elements / Q000235:genetics; D016415:Sequence Alignment; D014157:Transcription Factors / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D014327:Trophoblasts / Q000737:chemistry / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D050976:Basic-Leucine Zipper Transcription Factors; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; C103944:MAFG protein, human; D051259:MafG Transcription Factor; C117963:NFE2L3 protein, human; D012097:Repressor Proteins; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha