Related Experiment Videos
CpG methylation regulates the Igf2/H19 insulator.
C Holmgren1, C Kanduri, G Dell
1Department of Development and Genetics, Uppsala University, Norbyvägen 18A, S-752 36, Uppsala, Sweden.
Current Biology : CB
|August 18, 2001
Summary
CpG methylation regulates the H19 insulator function, controlling communication between enhancers and promoters. This methylation mark dictates parent-specific chromatin conformations and represses maternal Igf2 expression.
Area of Science:
- Genetics
- Epigenetics
- Genomic Imprinting
Background:
- The H19 gene's 5' flank, differentially methylated, regulates enhancer-promoter communication and represses maternal Igf2 expression.
- Paternally inherited Igf2 allele activation is linked to methylation-mediated inactivation of the H19 insulator during male germline development.
Purpose of the Study:
- To investigate the role of CpG methylation in regulating the H19 insulator function.
- To determine if methylation of the H19 imprinting control region (ICR) affects insulator activity and chromatin conformation.
Main Methods:
- Insertion of a methylated H19 ICR fragment into a nonmethylated episomal H19 minigene.
- Transfection into Hep3B cells and analysis of individual clones for genotype, methylation status, chromatin conformation, and insulator function.
Main Results:
- Methylated status of the H19 ICR was maintained without spreading to the episomal vector.
- Nuclease hypersensitive sites, typical of the maternal H19 ICR allele, were absent in the methylated ICR.
- Insulator function was significantly attenuated in stably maintained episomes.
Conclusions:
- CpG methylation of the H19 ICR is propagated independently of the episomal vector.
- Methylation dictates parent of origin-specific chromatin conformations, involving CTCF.
- Experimental evidence supports that CpG methylation regulates H19 insulator function.