Influence of c-Myc on Induction Efficiency and Pluripotency of Induced Pluripotent Stem Cells

Abstract: This work aimed to investigate the influence of transcription factor c-Myc on induction efficiency and pluripotency of induced pluripotent stem cells (iPS cells). We generated mouse iPS cells from OG2 mouse embryo fibroblasts (MEF) using retroviral virus delivered 4 factors (Oct-4， Sox-2， Klf-4 and c-Myc， OSKM) or 3 factors (Oct-4， Sox-2 and Klf-4， OSK). The number of iPS clones was counted under the microscope. The percentage of green fluorescent protein (GFP)-positive iPS cells was analyzed using flow cytometry. The induction efficiency of iPS was compared between OSKM and OSK. Reprogrammed colonies were picked and expanded into cell lines， which were further subjected to the stemness characterization: pluripotent marker expression， teratoma formation，chimera formation and tetraploid compensation. In our current induction system， compared to OSKM， our results showed that OSK induced iPS clones more efficiently and led to higher proportion of GFP-positive cells. Randomly picked iPS clones generated by OSKM or OSK possessed similar ES-like morphology， alkaline phosphatase (AP) positive staining， expression of pluripotent genes and ability to differentiate into three germ layers. However， the proportion of chimera generated by OSK clones was higher than OSKM clones and only OSK clones were able to produce chimeric mice with germline transmission and were capable of generating viable， live-born progeny by tetraploid complementation. Thus the present study demonstrated that in our current induction system， omitting c-Myc from the OSKM combination enhanced the reprogramming efficiency and improved pluripotency of generated iPS cells.

CSTR: 32200.14.cjcb.2014.04.0005