In 2006 Yamanaka and colleagues succeeded to convert somatic cells into induced pluripotent stem cells. To do so, they introduced four defined transcription factors, Oct-3/4, Sox2, Klf4 and c-Myc, by retroviral infection.
This methodology opens a new field in stem cell research, not only in terms of future medical applications but also for new approaches in gene targeting in animals where no stable ES cells are yet available like the rat.
The three goals of this work were: Firstly, the determination of differences in reprogramming efficiency in dependence of the genetic background of the rat cells used. Secondly, the generation efficiency of rat iPS (riPS) cells from wild type rat embryonic fibroblasts (REFs) before and after gene targeting. The third goal was to clarify the role of Pramel7, a protein that was recently shown to stabilize the pluripotent state of embryonic stem cells, in terms of reprogramming efficiency. For all reprogramming rounds three factors (Oct-3/4, Klf4, Sox2) were used.
By reprogramming REFs of the different genetic backgrounds no difference in the reprogramming efficiency could be obtained. The generation efficiency of riPS before and after gene targeting was similar, indicating that gene targeting does not affect the reprogramming potential. In this work we also could show that Pramel7 overexpression is sufficient to drive reprogramming in a LIF independent manner.