Maternal-specific methylation of the human IGF2R gene is not accompanied by allele-specific transcription

• Published in: Genomics (San Diego, Calif.) Vol. 31; no. 2; pp. 158 - 166
• Main Authors: RIESEWIJK, A. M, SCHEPENS, M. T, WELCH, T. R, VAN DEN BERG-LOONEN, E. M, MARIMAN, E. M, ROPERS, H.-H, KALSCHEUER, V. M
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier 15-01-1996
• Subjects: Alleles; Base Sequence; Biological and medical sciences; Chromosomes, Artificial, Yeast - genetics; Cloning, Molecular; CpG Islands - genetics; Fundamental and applied biological sciences. Psychology; Gene expression; Genome, Human; Humans; Methylation; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; Receptor, IGF Type 2 - genetics; Transcription, Genetic; Human; Allele; Maternal origin; Gene; DNA; Gene expression; Methylation; Insulin like growth factor 2; Conformation; Genomic imprinting; Biological receptor
• ISSN: 0888-7543; 1089-8646
• DOI: 10.1006/geno.1996.0027

The human insulin-like growth factor type 2 receptor gene (IGF2R) is biallelically expressed in a variety of fetal and adult tissues. In contrast, the imprinted mouse Igf2r gene is expressed exclusively from the maternally inherited chromosome. The mouse gene contains two CpG islands that are methylated in a parent-specific manner. Methylation of the CpG island in the promoter region occurs on the repressed paternal gene copy. Methylation of the CpG island in intron 2 is specific for the active maternal allele and may represent the primary imprint. Here, we have analyzed the human IGF2R gene to investigate whether these motifs and their parent-of-origin-specific epigenetic modification have been conserved. As in the mouse, the human IGF2R gene was found to contain two CpG islands, one encompassing the transcription start site (CpG 1) and the other in the second intron (CpG 2). CpG 2 is hypermethylated on the maternal IGF2R allele. In contrast to the situation in the mouse, however, the human CpG 1 is completely unmethylated on both parental chromosomes. The human and mouse intronic CpG islands lack significant sequence homology, which suggests that DNA conformation plays a role in allele-specific methylation.