The process of differentiation – in which a stem cell becomes a specialized mature blood cell – is controlled by a cascade of events in which specific genes are turned “on” and “off” in a highly regulated and accurate order.
The instructions for this process are contained within the DNA itself in short regulatory sequences. These regulatory regions are normally in a “closed” state masked by special proteins called histones to ensure against unwarranted activation. Therefore, to access and “activate” the instructions, this DNA mask needs to be “opened” by epigenetic modifications of the histones so it can be read by the necessary machinery.
In a paper published in Science, Dr. Ido Amit and David Lara-Astiaso of the Weizmann Institute’s Immunology Department, together with Prof. Nir Friedman and Assaf Weiner of the Hebrew University of Jerusalem, charted for the first time histone dynamics during blood development. Thanks to the new technique for epigenetic profiling they developed, in which just a handful of cells – as few as 500 – can be sampled and analyzed accurately, they have identified the exact DNA sequences, as well as the various regulatory proteins, that are involved in regulating the process of blood stem cell fate.
Their research has also yielded unexpected results: As many as 50 percent of these regulatory sequences are established and opened during intermediate stages of cell development. This means that epigenetics is active at stages in which it had been thought that cell destiny was already set.
“This changes our whole understanding of the process of blood stem cell fate decisions,” says Lara-Astiaso, “suggesting that the process is more dynamic and flexible than previously thought.”
Read the full, original story: Not only in DNA’s hands: Epigenetics has a large say in blood formation
