Transcription of human ABO histo-blood group genes is dependent upon binding of transcription factor CBF/NF-Y to minisatellite sequence.

Yoshihiko Kominato,Fumi-Ichiro Yamamoto,Terumasa Tsuchiya,Hisao Takizawa,Nobuhide Hata

doi:10.1074/jbc.272.41.25890

Abstract

We have studied the transcriptional regulatory mechanism of the human histo-blood group ABO genes, and identified DNA cis-elements and trans-activating protein that control the expression of these genes which are important in blood transfusion and organ transplantation. We introduced the 5'-upstream sequence of ABO genes into the promoterless reporter vector and characterized the promoter activity of deletion constructs using transient transfection assays with gastric cancer cell line KATO III cells. The sequence just upstream of the transcription start site (cap site), and an enhancer element, which is located further upstream (between -3899 and -3618 base pairs (bp) from the transcription initiation site) and contains 4 tandem copies of a 43-bp repeat unit, were shown in gastric cancer cells to be responsible for the transcriptional activity of the ABO genes. DNA binding studies have demonstrated that a transcription factor, CBF/NF-Y, bound to the 43-bp repeat unit in the minisatellite. Functional importance of these CBF/NF-Y-binding sites in enhancer activity was confirmed by transfection experiments using reporter plasmids with mutated binding sites. Thus, transcriptional regulation of the human ABO genes is dependent upon binding of CBF/NF-Y to the minisatellite.

Highlights

We have studied the transcriptional regulatory mechanism of the human histo-blood group ABO genes, and identified DNA cis-elements and trans-activating protein that control the expression of these genes which are important in blood transfusion and organ transplantation
We have identified sequences essential for the transcriptional control of the human ABO blood group genes
Transient transfection of KATO III cells with luciferase reporter constructs demonstrated the importance of the promoter sequence immediately upstream of the transcription start site in regulating the ABO gene expression

Summary

Introduction

We have studied the transcriptional regulatory mechanism of the human histo-blood group ABO genes, and identified DNA cis-elements and trans-activating protein that control the expression of these genes which are important in blood transfusion and organ transplantation. Histo-blood group ABH(O) antigens, the major alloantigens in humans [1], have been characterized as defined trisaccharide determinants GalNAc␣133(Fuc␣132)Gal␤13 R, Gal␣133(Fuc␣132)Gal␤13 R, and disaccharide determinant Fuc␣132Gal␤13 R for A, B, and H, respectively [2, 3] These structures represent the secondary gene products which are synthesized from the precursor H substrate by ␣133GalNAc (A transferase) and ␣133Gal transferase (B transferase), the primary gene products coded by the functional alleles at the ABO locus [4, 5]. Reduction or complete deletion of A/B antigen expression in primary lung, bladder, and colorectal carcinomas have been reported This phenotypic change was well correlated with the invasive and metastatic potentials of the tumors, and with 5- or 10-year mortality rates of the patients [10, 11]. Delineation of transcriptional regulation of the ABO genes, may provide clues as to the underlying mechanisms resulting in A/B antigen disappearance in cancer cells with invasive and metastatic potentials

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Results

Conclusion