Tissue-specific transcriptional regulation of human leukosialin (CD43) gene is achieved by DNA methylation.
The expression of human leukosialin (CD43), a major sialoglycoprotein on the surface of hematopoietic cells, is regulated in cell lineage-specific as well as differentiation stage-specific manners. We have shown previously that transcription from the TATA-less promoter is mediated by the transcription factor Sp1, which binds to repeats of a GGGTGG motif in the 5'-flanking sequence. This regulatory region is ubiquitously functional in mammalian cells, providing a high transcriptional potential. No cis-acting element responsible for the specificity of this gene expression was revealed by extensive studies using transient as well as stable expression systems. Here, we demonstrate that DNA methylation plays a key role in leukosialin gene expression. Southern blot analysis of genomic DNAs from various human cell lines with methylation-sensitive and -insensitive restriction enzymes showed a tight correlation between gene activity and demethylation state of the 5'-region of the leukosialin gene. Consistent results were obtained from the same analysis of genomic DNAs from various human tissues. In addition, in vitro DNA methylation of the 5'-region drastically reduced transcriptional activity in a transient expression system. These results indicate that DNA methylation around the 5'-region of the leukosialin gene is required to shut off a high level of transcription. Thus, the tissue-specific expression of the leukosialin gene is constitutively achieved by alteration of DNA methylation.
Kudo
S
S
La Jolla Cancer Research Foundation, Cancer Research Center, California 92037, USA.
Fukuda
M
M
D015703:Antigens, CD / Q000235:genetics*; D002460:Cell Line; D004247:DNA / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D051917:Leukosialin; D008745:Methylation; D012045:Regulatory Sequences, Nucleic Acid; D012795:Sialoglycoproteins / Q000235:genetics*; D014158:Transcription, Genetic
D015703:Antigens, CD; D051917:Leukosialin; C465014:SPN protein, human; D012795:Sialoglycoproteins; D004247:DNA