Generations: how cells inherit information

Epigenetics doesn’t just mean passing acquired changes from one generation of organism to its offspring. It also refers to the information passed from one generation of cells to the next within a single organism.

Each cell in our bodies contains the same genetic information, yet they are able to differentiate into hundreds of different types of specialised cell. The question is: how do they know what kind of cell to turn in to, and which portions of their DNA should they access to determine how they should function?

Now a study by a team of researchers at the Australian National University sheds light on this process by showing how epigenetic information is transmitted from one generation of cells to the next.

“We know cells are regenerating all the time and that epigenetic information must therefore be continually restored, the question is how this actually happens,” said lead researcher, Dr David Tremethick, from The John Curtin School of Medical Research.

“Our study focused on this important unanswered question by investigating how epigenetic information is restored following the cellular division of stem cells, which is essential for their renewal.

“Using mouse stem cells as a model system we found that the inheritance of epigenetic information, how information is passed along, was much more dynamic and unstable than we expected."

The mechanism itself concerns the key histone H2A.Z, which is central to transcriptional regulation and the silencing of specific genes within a cell. Tremethick and his team found that histone H2A.Z behaved in some unstable and unpredictable ways during cell division.

“From a health perspective, this has both positive and negative consequences. On the one hand, this instability opens up the possibility of information being corrupted as it is passed from cell to cell, causing disease. On the other, it points to the potential of one day being able to intervene in the process to correct corrupted information or stop it being passed on to another generation.

“The next step is to understand how this epigenomic information is naturally altered to allow the proper transition from a stem cell to a lineage-committed cell that occurs during human embryo development. This, in turn, will allow a better understanding of how this inheritance process goes wrong in diseases such as cancer."

The study was published this week in Nature Structural & Molecular Biology.