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. Author manuscript; available in PMC: 2012 Aug 30.
Published in final edited form as: Stem Cells. 2011 Sep;29(9):1349–1361. doi: 10.1002/stem.684

Figure 1.

Figure 1

Establishment of mouse induced pluripotent stem cells (iPSCs) with M3O-Sox2, Klf4, and c-Myc (SKM). (A): Schematic drawing of MyoD-Oct4 chimeric constructs. Numbers indicate amino acid positions delimiting MyoD fragments. The basic helix-loop-helix domain of MyoD corresponds to amino acids 108–167, which was not used in these chimeric constructs. EO indicates a polypeptide consisting of one methionine and a chain of 20 glutamic acids fused to Oct4 (E for glutamic acid). Right column shows percentage of green fluorescence protein (GFP)-positive colonies derived from mouse embryonic fibroblasts (MEFs) transduced with each MyoD-Oct4 chimeric construct along with SKM and cultured on feeder cells (Fig. 1B, protocol A). Data represent the mean + SEM from three independent experiments. (B): Schematic drawings of two protocols for iPSC creation. Although transduced MEFs were transferred onto feeder cells on day 4 in protocol A, MEFs were maintained feeder-free until the end of experiments in protocol B. (C): Emergence of GFP-positive colonies obtained with M3O-SKM with protocol B. Scale bar = 200 μm. (D): Summary of the efficiency of making GFP-positive colonies with various combinations of the M3O, Sox2, Klf4, and c-Myc genes with protocol B. Number of GFP-positive colonies peaked by day 14. (E): Drawings of various combinations of the M3 domain and Oct4. The efficiency of making GFP-positive colonies with protocol B in the presence of SKM is shown on the right. (F): Drawings of transactivation domain (TAD) replacement constructs in which TADs of Oct4 were replaced with the M3 domain. Constructs were transduced with SKM. (G): Drawings of fusion constructs between the M3 domain and Sox2 or Klf4. Sox2 mutants were transduced with OKM or M3O-KM. The Klf4 mutant was transduced with OSM or M3O-SM. (H): Drawings of fusion constructs between Oct4 and TADs taken from other transactivators. Constructs were transduced with SKM. Abbreviations: GFP, green fluorescence protein; OSKM, Oct4, Sox2, Klf4, and c-Myc; SKM, Sox2, Klf4, and c-Myc.