Transdifferentiation and cell reprogramming - do they obey the same rules?

Our lab is interested in understanding principles of mammalian cell fate specification, using transcription factor (TF)-induced cell conversions. Many somatic cell types are plastic, having the capacity to be converted either into other specialized cells (transdifferentiation) or to be reprogrammed into induced pluripotent stem cells (iPSCs) following forced TF expression. However, typically only a small fraction of cells respond, making it difficult to study these processes mechanistically. To overcome this hurdle, we have developed two efficient cell conversion systems that we use as models. Sustained expression of the myeloid cell-associated TF C/EBPa induces pre-B cells to transdifferentiate into macrophages while transient expression of the factor followed by the Yamanaka factors reprograms them into iPSCs at nearly 100% efficiencies. I will give an overview about our recent work with these systems and discuss evidence that transdifferentiation and cell reprogramming exhibit some fundamental differences.