Molecular Cloning and Functional Characterization of a New Cap’n’ Collar Family Transcription Factor Nrf3

doi:10.1074/jbc.274.10.6443

Molecular Cloning and Functional Characterization of a New Cap’n’ Collar Family Transcription Factor Nrf3*

From the ^‡Department of Biochemistry, Tohoku University School of Medicine, 2-1 Seiryomachi, Aoba-ku, Sendai 980-8575, ^¶Department of Pediatrics and ^‖Clinical Laboratory, Hirosaki University School of Medicine, Zaifu-cho, Hirosaki 036, and ^**Center for Tsukuba Advanced Research Alliance and Institute of Basic Medical Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba 305-8577, Japan

Abstract

The NF-E2-binding sites or Mafrecognition elements (MARE) are essentialcis-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 β-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, andnrf2 have been mapped close to those ofhoxC, 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.

Footnotes

↵* This work was supported by Grants-in-Aid from the Ministry of Education, Science, Sports, and Culture, Core Research for Evolutional Science and Technology, and the Japanese Society for the Promotion of Sciences.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EMBL Data Bank with accession number(s) AB010812 (human) and AB013852 (mouse).
↵§ To whom correspondence should be addressed: Dept. of Biochemistry, Tohoku University School of Medicine, 2-1 Seiryomachi, Aoba-ku, Sendai 980-8575, Japan. Tel.: 81-22-717-8088; Fax: 81-22-717-8090; E-mail:akira-k{at}mail.cc.tohoku.ac.jp.
↵2 A. Kobayashi, unpublished observations.
↵3 K. Igarashi and M. Yamamoto, unpublished observations.
Abbreviations:

bZip

basic region-leucine zipper

CNC

Cap’n’ collar

EMSA

electrophoretic gel mobility shift analysis

EST

expressed sequence tag

FISH

fluorescence in situ hybridization

MARE

Maf recognition element

MBP

maltose-binding protein

Nrf3

NF-E2-related factor 3

LCR

locus control region

UTR

untranslated region

bp

base pair(s)

kbp

kilobase pair(s)

PCR

polymerase chain reaction

GAD

GAL4 activation domain

GBD

GAL4 DNA-binding domain
- Received June 29, 1998.
- Revision received November 12, 1998.
The American Society for Biochemistry and Molecular Biology, Inc.