Molecular cloning and functional characterization of a new Cap'n' collar family transcription factor Nrf3.
The NF-E2-binding sites or Maf recognition elements (MARE) are essential cis-acting elements in the regulatory regions of erythroid-specific genes recognized by the erythroid transcription factor NF-E2, composed of p45 and MafK. Recently, two p45-related factors Nrf1 and Nrf2 were isolated, and they are now collectively grouped as the Cap'n' collar (CNC) family. CNC factors bind to MARE through heterodimer formation with small Maf proteins. We report here the identification and characterization of a novel CNC factor, Nrf3, encoding a predicted 73-kDa protein with a basic region-leucine zipper domain highly homologous to those of other CNC proteins. In vitro and in vivo analyses showed that Nrf3 can heterodimerize with MafK and that this complex binds to the MARE in the chicken beta-globin enhancer and can activate transcription. Nrf3 mRNA is highly expressed in human placenta and B cell and monocyte lineage. Chromosomal localization of human Nrf3 is 7p14-15, which lies near the hoxA gene locus. As the genetic loci of p45, nrf1, and nrf2 have been mapped close to those of hoxC, hoxB, and hoxD, respectively, the present study strongly argues for the idea that a single ancestral gene for the CNC family members may have been localized near the ancestral Hox cluster and have diverged to give rise to four closely related CNC factors through chromosome duplication.
Kobayashi
A
A
Department of Biochemistry, Tohoku University School of Medicine, 2-1 Seiryomachi, Aoba-ku, Sendai 980-8575, Japan. akira-k@mail.cc.tohoku.ac.jp
Ito
E
E
Toki
T
T
Kogame
K
K
Takahashi
S
S
Igarashi
K
K
Hayashi
N
N
Yamamoto
M
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D050976:Basic-Leucine Zipper Transcription Factors; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics; D050981:Erythroid-Specific DNA-Binding Factors; D006367:HeLa Cells; D006801:Humans; D050985:MafK Transcription Factor; D051379:Mice; D008969:Molecular Sequence Data; D050983:NF-E2 Transcription Factor; D050984:NF-E2 Transcription Factor, p45 Subunit; D009687:Nuclear Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D016415:Sequence Alignment; D014157:Transcription Factors / Q000235:genetics*
D050976:Basic-Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; C494695:MAFK protein, human; D050985:MafK Transcription Factor; C494696:Mafk protein, mouse; D050983:NF-E2 Transcription Factor; D050984:NF-E2 Transcription Factor, p45 Subunit; C494692:NFE2 protein, human; C117963:NFE2L3 protein, human; C494693:Nfe2 protein, mouse; D009687:Nuclear Proteins; D012333:RNA, Messenger; D014157:Transcription Factors