Mysteries of Epigenetics: There's More to Genes Than DNA - SciTechDaily

Biologists at the Universities of Bath and Vienna have discovered 71 new ‘imprinted’ genes in the mouse genome, a finding that takes them a step closer to unraveling some of the mysteries of epigenetics – an area of science that describes how genes are switched on (and off) in different cells at different stages in development and adulthood.

To understand the importance of imprinted genes to inheritance, we need to step back and ask how inheritance works in general.

Until now, researchers were aware of around 130 well-documented imprinted genes in the mouse genome – the new additions take this number to over 200.

Close examination of the newly identified genes has allowed Professor Perry and his colleagues to make a second important discovery: the switching on and off of imprinted genes is not always related to DNA methylation, where methyl groups are added to genomic DNA (a process that is known to repress gene activity, switching them off).

Although scientists have known for some time that histones act as ‘dimmer’ switches for genes, fading them off (or back on), until now it was thought that DNA methylation provided the major switch for imprinted gene activity.

The findings from the new study cast doubt on this assumption: many of the newly identified genes were found to be associated with changes to the histone 3 lysine 27 (H3K27me3), and only a minority with DNA methylation.

Scientists have yet to work out how one parental version of a given gene can be switched (or faded) on or off and maintained that way while the other is in the opposite state.

This new study points to the intriguing possibility that some imprinted genes may not be marked in gametes, but become active later in development, or even in adulthood.

If it goes wrong, and the imprinted gene copy from one parent is switched on when it should be off (or vice versa), disease or death occur.

Faulty imprinted genes are associated with many diseases, including neurological and metabolic disorders, and cancer.

“We may underestimate how important the relationship between imprinting and disease is, as well as the relationship of imprinting to the inheritance of parentally-acquired disease, such as obesity,” said Professor Perry.

Reference: “Genomic imprinting in mouse blastocysts is predominantly associated with H3K27me3” by Laura Santini, Florian Halbritter, Fabian Titz-Teixeira, Toru Suzuki, Maki Asami, Xiaoyan Ma, Julia Ramesmayer, Andreas Lackner, Nick Warr, Florian Pauler, Simon Hippenmeyer, Ernest Laue, Matthias Farlik, Christoph Bock, Andreas Beyer, Anthony C.

June 20, 2021

June 20, 2021