Alternative promoter identified between a hypermethylated upstream region of repetitive elements and a CpG island in human ABO histo-blood group genes.
We have studied the expression of human histo-blood group ABO genes during erythroid differentiation, using an ex vivo culture of AC133(-)CD34(+) cells obtained from peripheral blood. 5'-Rapid amplification of cDNA ends analysis of RNA from those cells revealed a novel transcription start site, which appeared to mark an alternative starting exon (1a) comprising 27 bp at the 5'-end of a CpG island in ABO genes. Results from reverse transcription-PCR specific to exon 1a indicated that the cells of both erythroid and epithelial lineages utilize this exon as the transcription starting exon. Transient transfection experiments showed that the region just upstream from the transcription start site possesses promoter activity in a cell type-specific manner when placed 5' adjacent to the reporter luciferase gene. Results from bisulfite genomic sequencing and reverse transcription-PCR analysis indicated that hypermethylation of the distal promoter region correlated with the absence of transcripts containing exon 1a, whereas hypermethylation in the interspersed repeats 5' adjacent to the distal promoter was commonly observed in all of the cell lines examined. These results suggest that a functional alternative promoter is located between the hypermethylated region of repetitive elements and the CpG island in the ABO genes.
Kominato
Yoshihiko
Y
First Department of Internal Medicine, Toyama Medical and Pharmaceutical University, Faculty of Medicine, Toyama 930-0194, Japan. ykomilm@ms.toyama-mpu.ac.jp
Hata
Yukiko
Y
Takizawa
Hisao
H
Matsumoto
Kayoko
K
Yasui
Kazuta
K
Tsukada
Jun-Ichi
J
Yamamoto
Fumi-Ichiro
F
D020121:5' Untranslated Regions / Q000235:genetics*; D000017:ABO Blood-Group System / Q000235:genetics*; D001483:Base Sequence; D002478:Cells, Cultured; D019175:DNA Methylation; D017931:DNA Primers; D018076:DNA, Complementary / Q000235:genetics; D015226:Dinucleoside Phosphates / Q000378:metabolism*; D005091:Exons; D017930:Genes, Reporter; D006801:Humans; D019169:Jurkat Cells; D020014:K562 Cells; D008156:Luciferases / Q000235:genetics; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012091:Repetitive Sequences, Nucleic Acid; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013274:Stomach Neoplasms; D014407:Tumor Cells, Cultured
D020121:5' Untranslated Regions; D000017:ABO Blood-Group System; D017931:DNA Primers; D018076:DNA, Complementary; D015226:Dinucleoside Phosphates; D008156:Luciferases; C015772:CpG dinucleotide