Quick, Coordinated and Authentic Reprogramming of Ribosome Biogenesis during iPSC Reprogramming.

Induction of pluripotent stem cells (iPSC) by OCT4 (octamer-binding transcription factor 4), SOX2 (SR box 2), KLF4 (Krüppel-Like Factor 4), and MYC (cellular Myelocytomatosis, c-MYC or MYC) (collectively OSKM) is revolutionary, but very inefficient, slow, and stochastic. It is unknown as to what underlies the potency aspect of the multi-step, multi-pathway, and inefficient iPSC reprogramming. Mesenchymal-to-epithelial (MET) transition is known as the earliest pathway reprogrammed. Using the recently established concepts of reprogramome and reprogramming legitimacy, the author first demonstrated that ribosome biogenesis (RB) is globally enriched in terms of human embryonic stem cells in comparison with fibroblasts, the popular starting cells of pluripotency reprogramming. It is then shown that the RB network was reprogrammed quickly in a coordinated fashion. Human iPSCs also demonstrated a more robust ribosome biogenesis. The quick and global reprogramming of ribosome biogenesis was also observed in an independent fibroblast line from a different donor. This study additionally demonstrated that MET did not initiate substantially at the time of proper RB reprogramming. This quick, coordinated and authentic RB reprogramming to the more robust pluripotent state by the OSKM reprogramming factors dramatically contrasts the overall low efficiency and long latency of iPSC reprogramming, and aligns well with the potency aspect of the inefficient OSKM reprogramming.