A fertilized egg can become every type of cell in the body, but how does it do it? We're still learning
Epigenetics is one of the reasons you have an organised body, full of different types of cells doing different jobs. Epigenetics is all about controlling gene activity, switching on or off various genes to change a cell's identity and behaviour. In the fertilization process, cells undergo a reprogramming process to give the new cells a clean slate (mostly), and this flexibility is a central part of what makes stem cells so wonderful. Regardless of how much we've accomplished so far however, we're still learning and recent studies suggest we've missed some crucial points on exactly how this reprogramming works.
All important methylation
One of the major ways genes are regulated is through a process called methylation. This means attaching methyl groups to elements of DNA to regulate their activity - a bit like a genetic padlock that alters the gene's activity.
Many of these methyl groups are wiped clean at fertilization, and added on anew to create a growing infant. We previously thought we knew how this was accomplished in the fertilized egg, but new research suggests we were missing a considerable chunk of the story.
"What we've shown is that the Tet explanation is partly true, but it's not the complete story. We tried to dig a little deeper"
Until now many scientists believed methyl groups were removed by an enzyme called Tet, but a new study has revealed that when this was absent cells were still able to remove these chemical tags. This was also the case when they blocked Tet's activity, indicating there's something else doing the job too that we don't know about yet. The researchers used cutting edge mass spectroscopy to analyse the DNA strands to ascertain the level of methylation.
"We found that the reprogramming process is much more complicated than previously thought. There is a constant race between the mechanisms removing the chemical modifications, and the mechanisms trying to put them back into place. When we want to reprogramme a cell, we have to think about both -- how to remove the modifications and, equally importantly, how to protect the newly unmodified DNA from becoming modified again"
We are able to make stem cells in the lab from adult cells, but they only undergo partial reprogramming in comparison to their embryonic varieties. While they're proving effective in some studies, finding out how to mirror exactly what happens after fertilization will likely unveil ways of enhancing stem cell science and safety even more.
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