Mature cells develop through a number of immature stages. During this process, they must remember the specialization they are committed to. For immune system B cells, Rudolf Grosschedl of the Max Planck Institute of Immunobiology and Epigenetics and his team have discovered that the transcription factor EBF1 is crucial for B cells to remember who they are. When the researchers switched off the transcription factor, the cells lost their previous identity and developed into T cells. Unlike most other cell types, B cells have a characteristic footprint in their genetic makeup and this allowed the researchers to identify the origin of each individual cell.
During the transition from stem cells to becoming a functional part of the immune system, cells must undergo a number of specialization stages where they have the opportunity to decide between pathways leading to the various cell types found in the blood. It is also important that once they have chosen a specialization, they remain committed to it.
Immune system B and T cells come from the same stem cell. Rudolf Grosschedl and his colleagues were able to prove as early as 1995 that the transcription factor EBF1 is active only in some of these cells and this induces their development into B cells. Until now, however, it was unclear whether EBF1 also played a part in constantly reminding the B cells of their identity.
B cells usually die when EBF1 is switched off. In collaboration with researchers from the University of Freiburg, the Max Planck researchers collected mouse B cells at a late stage of their development and transferred them to mice lacking an immune system. They then switched off the EBF1 gene in the transplanted B cells. After three months, they checked whether immune cells were still present in the mice. "We thought that the chance of this transfer enabling the cells to remain alive was slim, so we were very pleased that it worked," says Robert Nechanitzky, a doctoral stu
|Contact: Dr. Rudolf Grosschedl|