2000 Fiscal Year Final Research Report Summary
Expression of human histo-blood group ABO genes is dependent upon DNA methylation of the promoter region
| Project/Area Number |
11670410
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Legal medicine
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| Research Institution | TOYAMA MEDICAL AND PHARMACEUTICAL UNIVERSITY |
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Principal Investigator |
KOMINATO Yoshihiko TOYAMA MEDICAL AND PHARMACEUTICAL UNIVERSITY Faculty of Medicine Lecturer, 医学部, 講師 (30205512)
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| Co-Investigator(Kenkyū-buntansha) |
HATA Yukiko TOYAMA MEDICAL AND PHARMACEUTICAL UNIVERSITY Faculty of Medicine Research assistant, 医学部, 教務職員 (30311674)
TAKIZAWA Hisao TOYAMA MEDICAL AND PHARMACEUTICAL UNIVERSITY Faculty of Medicine Professor, 医学部, 教授 (90171579)
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| Project Period (FY) |
1999 – 2000
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| Keywords | the human ABO blood group genes / transcription / promoter assay / CpG island / DNA methylation |
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| Research Abstract |
We have studied the transcriptional regulatory mechanism of the human histo-blood group ABO genes. The promoter assay using transient transfection showed that the sequence just upstream of the transcription start site (cap site) and an enhancer element which is located further upstream (between -3899 and -3618 bp from the transcription initiation site) are responsible for the transcriptional activity of the ABO genes in gastric cancer cells. Electrophoretic mobility shift assays showed that a transcriptional factor, CBF/NF-Y binds the minisatellite, which is essential for the enhancer activity, on between -3899 and -3618 bp from the transcription initiation site. However, the promoter assay demonstrated that the proximal promoter is active in the cells not expressing the ABO genes. Next, mechanism of repression of the ABO genes in tumors was investigated. The promoter region of the ABO genes fulfills the criteria for CpG island, having a G+C content of greater than 60% and having a CpG
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/GpC ratio of at least 0.6. Methylated CpG islands are associated with long-range changes in chromatin, which mediate a closed, nucleosomal conformation, and transcriptional repression. Therefore, we have investigated the role of DNA methylation in the regulation of the expression of the human ABO blood group genes. Studies on the methylation of the ABO blood group gene promoter in cultured cells demonstrated that the promoter is methylated in vivo in the cells not expressing the ABO genes, and that hypomethylation of the promoter is correlated with constitutive gene expression. Demethylation of the promoter in vivo by treatment of the cells with 5-aza-2'-deoxycytidine led to the expression of A-antigens on gastric cancer cells and hypermethylation of the promoter in vitro suppressed the promoter activity. These results indicated that DNA methylation of the ABO gene promoter regulates gene expression, suggesting that alternations in DNA methylation may be one of the mechanisms regulating the loss of ABO antigens in the tumors. Less
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Research Products
(12 results)
