The ROSA26-iPSC mouse: a conditional, inducible, and exchangeable resource for studying cellular (De)differentiation

Control of cellular (de)differentiation in a temporal, cell-specific, and exchangeable manner is of paramount importance in the field of reprogramming. Here, we have generated and characterized a mouse strain that allows iPSC generation through the Cre/loxP conditional and doxycycline/rtTA-controlled inducible expression of the OSKM reprogramming factors entirely from within the ROSA26 locus. After reprogramming, these factors can be replaced by genes of interest-for example, to enhance lineage-directed differentiation-with the use of a trap-coupled RMCE reaction. We show that, similar to ESCs, Dox-controlled expression of the cardiac transcriptional regulator Mesp1 together with Wnt inhibition enhances the generation of functional cardiomyocytes upon in vitro differentiation of such RMCE-retargeted iPSCs. This ROSA26-iPSC mouse model is therefore an excellent tool for studying both cellular reprogramming and lineage-directed differentiation factors from the same locus and will greatly facilitate the identification and ease of functional characterization of the genetic/epigenetic determinants involved in these complex processes. There has been much interest in altering cell fate by the ectopic expression of potent transcription factors. Therefore, Haigh and colleagues have now developed a reprogrammable mouse model for creating induced pluripotent stem cells (iPSCs) through overexpression of the so-called Yamanaka reprogramming factors in a tissue-/cell-specific and temporally controlled manner. Moreover, in iPSCs resulting from this ROSA26-iPSC model, researchers can efficiently exchange the Yamanaka factors with other genes of interest to enhance their lineage-directed differentiation potential. ? 2013 The Authors.