Identification of Bach2 as a B-cell-specific partner for small maf proteins that negatively regulate the immunoglobulin heavy chain gene 3' enhancer.
Maf family transcription factors are important regulators in various differentiation systems. Putative Maf recognition elements (MAREs) are found in the 3' enhancer region of the immunoglobulin heavy chain (IgH) gene. These elements are bound in B-cell extracts by a heterodimeric protein complex containing both Bach2 and a small Maf protein. Analysis of normal hematopoietic cells revealed that Bach2 is specifically expressed in B cells. Bach2 is abundantly expressed in the early stages of B-cell differentiation and turned off in terminally differentiated cells. Bach2 acts together with MafK as a negative effector of the IgH 3' enhancer and binds to the co-repressor SMRT (silencing mediator of retinoid and thyroid receptor). Hence the Bach2-small-Maf heterodimer may represent the first example of a B-cell lineage, and of a developmental stage-restricted negative effector of the MARE in the IgH 3' enhancer region.
Department of Biochemistry, Tohoku University School of Medicine, Seiryo-machi, Aoba-ku, Sendai 980-8575, USA.
A
A
Muto
H
H
Hoshino
L
L
Madisen
N
N
Yanai
M
M
Obinata
H
H
Karasuyama
N
N
Hayashi
H
H
Nakauchi
M
M
Yamamoto
M
M
Groudine
K
K
Igarashi
D001402:B-Lymphocytes / Q000378:metabolism*; D050976:Basic-Leucine Zipper Transcription Factors; D002454:Cell Differentiation; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D005786:Gene Expression Regulation; D005803:Genes, Immunoglobulin; D006412:Hematopoietic Stem Cells / Q000378:metabolism; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D016350:Leucine Zippers; D050985:MafK Transcription Factor; D009687:Nuclear Proteins / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051257:Proto-Oncogene Proteins c-maf; D020218:Response Elements; D014157:Transcription Factors / Q000378:metabolism*
C102109:Bach2 protein, mouse; D050976:Basic-Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; D007143:Immunoglobulin Heavy Chains; D050985:MafK Transcription Factor; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D051257:Proto-Oncogene Proteins c-maf; D014157:Transcription Factors