Expresion and methylation analysis of adult somatic cell lines, five days after OSK, AOX15 and AO9 overxpression and derived iPSC using the different combinations

Methods of reprogramming somatic cells to an induced pluripotent state (iPSC) have enabled the direct modeling of human disease and ultimately promise to revolutionize regenerative medicine. iPSCs offer an invaluable source of patient-specific pluripotent stem cells for disease modeling, drug screening, toxicology tests and importantly for regenerative medicine, and already have been employed to unmask novel insights into human diseases. While iPSCs can be consistently generated through overexpression of the four Yamanaka Factors OCT4, SOX2, KLF4 and c-MYC (OSKM), reprogrammed cells present worrisome differences with embryonic stem cells in transcriptional and epigenetic profiles, as well as developmental potential and difficulties in cell culturing. A thorough mechanistic understanding of the reprogramming process is critical to overcoming these barriers to the clinical use of iPSC. We have recently published a novel factor combination based on molecules specifically enriched in the metaphase II human oocyte. We have shown that just the overexpression of histone-remodeling chaperone ASF1A and OCT4 in hADFs previously exposed to the oocyte-specific paracrine growth factor GDF9 can reprogram hADFs into pluripotent cells (AO9-iPSCs). Our study contributes to the understanding of the molecular pathways governing somatic cell reprogramming. Here we want to go deeper in the reprogramming mechanisms by understanding the importance of somatic cell origin, and analyzing (and establishing comparison with) the transcriptional and epigenetic characteristics of AO9-iPSCs. As the intrinsic histone chaperone activity of ASF1A and our data indicate, these cells could be closer to the embryonic pluripotent state, with less epigenetic memory, better culture properties and differentiation potential.

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Lopez-Caraballo L, Martorell-Marugan J, Carmona-Saez P, Gonzalez-Muñoz E