Crucial Role of C-Myc in the Generation of Induced Pluripotent Stem Cells

Abstract

c-Myc transduction has been considered previously to be nonessential for induced pluripotent stem cell (iPSC) generation. In this study, we investigated the effects of c-Myc transduction on the generation of iPSCs from an inbred mouse strain using a genome integration-free vector to exclude the effects of the genetic background and the genomic integration of exogenous genes. Our findings reveal a clear difference between iPSCs generated using the four defined factors including c-Myc (4F-iPSCs) and those produced without cMyc (3F-iPSCs). Molecular and cellular analyses did not reveal any differences between 3F-iPSCs and 4F-iPSCs, as reported previously. However, a chimeric mice formation test indicated clear differences, whereby few highly chimeric mice and no germline transmission was observed using 3F-iPSCs. Similar differences were also observed in the mouse line that has been widely used in iPSC studies. Furthermore, the defect in 3F-iPSCs was considerably improved by trichostatin A, a histone deacetyl transferase inhibitor, indicating that c-Myc plays a crucial role in iPSC generation through the control of histone acetylation. Indeed, low levels of histone acetylation were observed in 3F-iPSCs. Our results shed new light on iPSC generation mechanisms and strongly recommend c-Myc transduction for preparing highquality iPSCs.

Roles for MYC in the Establishment and Maintenance of Pluripotency

“…This discovery complemented previous work that showed the concept of reprogramming by nuclear transfer technologies (Gurdon et al 1958;Gurdon and Uehlinger 1966) but in addition, created new opportunities for human disease modeling, drug screening, and regenerative medicine. Many variations to Yamanaka's original approach have now been described (Buganim et al 2012), including the substitution of MYC with other factors including the histone deacetylase (HDAC) inhibitors valproic acid (Huangfu et al 2008) and trichostatin A (Araki et al 2011). Presumably, these factors mimic the effects of MYC in the reprogramming process by promoting the formation of euchromatin.…”

“…As mentioned above, MYC can be omitted from reprogramming cocktails but questions have been raised as to the quality of reprogrammed cells generated under different conditions. One recent report provides evidence that MYC is essential to generate fully reprogrammed cells and that this is dependent on its ability to recruit HAT complexes to target genes (Araki et al 2011). The use of wild-type MYC in clinical settings to generate PSCs is currently not favored because of its potential to deregulate cell proliferation (Okita et al 2007) but one group recently showed that the ability of MYC to reprogram may be independent of its role in transformation (Nakagawa et al 2010).…”

MYC/MAX control ERK signaling and pluripotency by regulation of dual-specificity phosphatases 2 and 7

“…Roles for MYC and MYCN in maintenance of pluripotency and cell reprogramming (Takahashi and Yamanaka 2006;Nakagawa et al 2010;Araki et al 2011) have been firmly established, although mechanisms of MYC function remain unclear. Deletion of MYC and MYCN in murine pluripotent stem cells (mPSCs) results in loss of pluripotency and differentiation toward primitive endoderm Varlakhanova et al 2010).…”

Transplantation of Adipose-Derived Stem Cells in Stroke

“…On the other hand, although the discovery of iPSC seems to offer a solution to the problem of the limited availability of stem cells through reprogramming of autologous somatic cells (Takahashi and Yamanaka, 2006), the requirement for the activation of potentially tumorigenic genes (e.g. c-myc) for its induction (Araki et al 2011) has raised much clinical concerns. ADSC, therefore, appear to be an applicable clinical tool for routine clinical practice.…”