What is it about?
In female mammals, one of their two X chromosomes is silenced (most genes are turned off) in a process called X chromosome inactivation. In humans, the choice of which X chromosome is silenced is random. Therefore, the X inherited from either the mother or the father has an equal probability of being silenced. In marsupials, females alway silence the X chromosome inherited from their father. For decades there has been no understanding of the signal that results in the fathers X being switch off. We show that the X chromosome inherited from the father arrives at the egg with chemical modifications that reflects the silent X in adult females. We propose that the X inherited from the father is primmed for silencing pre-fertilisation, and that this is the long sought after signal responsible for it always being turned of.
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Why is it important?
Our findings represent the first candidate mechanism that results in the fathers X always being silenced in female offspring. This provides fundamental understanding of gene regulation.
Perspectives
Discovering the patterns we observed in our data was a surprise. We never expected that the signal to silence the fathers X would be chromosome wide. It highlights how biology can be surprising.
A/Prof Paul Waters
University of New South Wales
Read the Original
This page is a summary of: Imprinted X chromosome inactivation in marsupials: The paternal X arrives at the egg with a silent DNA methylation profile, Proceedings of the National Academy of Sciences, August 2024, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2412185121.
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