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Preferential X-chromosome inactivation, DNA methylation and imprinting
Development (Cambridge, England). Supplement
|January 1, 1990
Summary
Parental imprinting establishes non-random X-chromosome inactivation in mammals. DNA methylation patterns are crucial for this process, with specific sites methylated early in development, but not the primary imprint for paternal X inactivation.
Area of Science:
- Genetics
- Epigenetics
- Developmental Biology
Background:
- Non-random X-chromosome inactivation is an early example of gamete-origin-dependent gene expression.
- Paternally inherited X chromosomes are preferentially inactivated in marsupials and rodent extra-embryonic tissues.
- Parental imprinting during gametogenesis is hypothesized to provide a signal for non-random X-inactivation, but its nature remains unknown.
Purpose of the Study:
- To investigate the timing of methylation differences that influence X-chromosome activity and imprinting during early development.
- To examine the establishment of methylation patterns related to X-chromosome inactivation and imprinting.
Main Methods:
- Studied methylation of a specific CpG site linked to the X-linked PGK-1 gene.
- Examined methylation and demethylation processes during early development.
- Investigated changes in DNA methylase activity.
Main Results:
- The specific CpG site associated with the X-linked PGK-1 gene is methylated on the inactive X chromosome by 6.5 days of gestation.
- This methylation occurs near the time of X-chromosome inactivation.
- Differential methylation at this site is not the primary imprint for preferential paternal X inactivation in extra-embryonic membranes.
Conclusions:
- Methylation and demethylation processes, along with DNA methylase activity, are dynamic during early development.
- While specific CpG methylation occurs early, it does not appear to be the initial imprinting mark for paternal X inactivation in extra-embryonic tissues.