Imprinting regulation of the murine Meg1/Grb10 and human GRB10 genes; roles of brain-specific promoters and mouse-specific CTCF-binding sites.
The imprinted mouse gene Meg1/Grb10 is expres sed from maternal alleles in almost all tissues and organs, except in the brain, where it is expressed biallelically, and the paternal allele is expressed preferentially in adulthood. In contrast, the human GRB10 gene shows equal biallelic expression in almost all tissues and organs, while it is almost always expressed paternally in the fetal brain. To elucidate the molecular mechanisms of the complex imprinting patterns among the different tissues and organs of humans and mice, we analyzed in detail both the genomic structures and tissue-specific expression profiles of these species. Experiments using 5'-RACE and RT-PCR demonstrated the existence in both humans and mice of novel brain- specific promoters, in which only the paternal allele was active. The promoters were located in the primary differentially methylated regions. Interest ingly, CTCF-binding sites were found only in the mouse promoter region where CTCF showed DNA methylation-sensitive binding activity. Thus, the insulator function of CTCF might cause reciprocal maternal expression of the Meg1/Grb10 gene from another upstream promoter in the mouse, whereas the human upstream promoter is active in both parental alleles due to the lack of the corresponding insulator sequence in this region.
Hikichi
Takafusa
T
Gene Research Center, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan.
Kohda
Takashi
T
Kaneko-Ishino
Tomoko
T
Ishino
Fumitoshi
F
D000483:Alleles; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D001921:Brain / Q000378:metabolism; D000076246:CCCTC-Binding Factor; D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D051383:GRB10 Adaptor Protein; D005786:Gene Expression Regulation; D018392:Genomic Imprinting; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D008954:Models, Biological; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D011506:Proteins / Q000235:genetics* / Q000378:metabolism; D012097:Repressor Proteins; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic
D000076246:CCCTC-Binding Factor; C000619697:CTCF protein, human; C000619698:Ctcf protein, mouse; D004268:DNA-Binding Proteins; C495959:Grb10 protein, mouse; D011506:Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D051383:GRB10 Adaptor Protein