Transduction of a murine dominant negative activation transcription factor 1 increases cell surface expression of the class I MHC on a human epidermoid tumor cell line.
The transcription of the MHC class I genes is regulated by interaction of cis-elements, located in the 5' genomic flanking regions, with sequence-specific trans-factors. We have identified a cis-regulatory element, 5'-TGACGCG-3', of the H-2D(d) gene. This cyclic adenosine-3',5'-monophosphate regulatory element (CRE)-like sequence, named H-2 binding factor 1 (H-2 BF1) binding motif, is highly conserved among species. In addition, we found that homo- and heterodimers of activation transcription factor 1 (ATF-1) and CRE binding protein (CREB) associate with the H-2 BF1 binding motif and activate transcription of the H-2D(d) gene. Here we demonstrate that a homologue of ATF-1, originally isolated and designated ATF-1DN, acts as a dominant repressor, blocking the ability of wild-type ATF-1 and CREB to bind to the H-2 BF1 probe in electrophoretic mobility shift assays (EMSA). We have utilized this molecule to analyze the participation of the H-2 BF1 complexes, consisting of the H-2 BF1 binding motif and ATF-1/CREB trans-factors, in the physiological regulation of MHC class I expression in tissue culture cells. A human epidermoid carcinoma cell line, A431, was transfected with ATF-1DN and clones expressing the gene transcripts were selected. When analyzed in the EMSA, nuclear proteins prepared from these clones exhibited a decreased shift of the H-2 BF1 probe corresponding to the levels of the ATF-1DN gene expression. Additionally, MHC class I expression of cells with reduced H-2 BF1 activity was significantly higher than in control cells lacking ATF-1DN. These findings indicate that in these carcinoma cells, the H-2 BF1 complexes negatively regulate the constitutive expression of MHC class I.
Ishizu
A
A
Department of Pathology and Kaplan Cancer Center, New York University Medical Center, 550 First Avenue, New York, NY 10016, USA.
Sawai
K
K
Ikeda
H
H
Hirano
T
T
Ishiguro
N
N
Meruelo
D
D
D051697:Activating Transcription Factor 1; D000818:Animals; D002462:Cell Membrane / Q000276:immunology*; D003001:Cloning, Molecular; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D005805:Genes, MHC Class I; D006183:H-2 Antigens / Q000378:metabolism*; D064532:Histocompatibility Antigen H-2D; D006801:Humans; D051379:Mice; D009355:Neomycin / Q000494:pharmacology; D012097:Repressor Proteins / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured
D051697:Activating Transcription Factor 1; C497100:Atf1 protein, mouse; D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; D006183:H-2 Antigens; D064532:Histocompatibility Antigen H-2D; D012097:Repressor Proteins; D014157:Transcription Factors; D009355:Neomycin