Nuclear transcriptome profiling of induced pluripotent stem cells and embryonic stem cells identify non-coding loci resistant to reprogramming

ABSTRACTIdentification of functionally relevant differences between induced pluripotent stem cells (iPSC) and reference embryonic stem cells (ESC) remains a central question for therapeutic applications. Differences in gene expression between iPSC and ESC have been examined by microarray and more recently with RNA-SEQ technologies. We here report an in depth analyses of nuclear and cytoplasmic transcriptomes, using the CAGE (cap analysis of gene expression) technology, for five iPSC clones derived from mouse lymphocytes B and three ESC lines. This approach reveals nuclear transcriptomes significantly more complex in ESC than in iPSC. Hundreds of yet not annotated putative non-coding RNAs and enhancer-associated transcripts specifically transcribed in ESC have been detected and supported with epigenetic and chromatin-chromatin interactions data. We identified super-enhancers transcriptionally active specifically in ESC and associated with genes implicated in the maintenance of pluripotency. Similarly, we detected non-coding transcripts of yet unknown function being regulated by ESC specific super-enhancers. Taken together, these results demonstrate that current protocols of iPSC reprogramming do not trigger activation of numerous <i>cis</i>-regulatory regions. It thus reinforces the need for already suggested deeper monitoring of the non-coding transcriptome when characterizing iPSC clones. Such differences in regulatory transcript expression may indeed impact their potential for clinical applications.