Context-dependent enhancement of induced pluripotent stem cell reprogramming by silencing Puma.
Reprogramming of the somatic state to pluripotency can be induced by a defined set of transcription factors including Oct3/4, Sox2, Klf4, and c-Myc [Cell 2006;126:663-676]. These induced pluripotent stem cells (iPSCs) hold great promise in human therapy and disease modeling. However, tumor suppressive activities of p53, which are necessary to prevent persistence of DNA damage in mammalian cells, have proven a serious impediment to formation of iPSCs [Nat Methods 2011;8:409-412]. We examined the requirement for downstream p53 activities in suppressing efficiency of reprogramming as well as preventing persistence of DNA damage into the early iPSCs. We discovered that the majority of the p53 activation occurred through early reprogramming-induced DNA damage with the activated expression of the apoptotic inducer Puma and the cell cycle inhibitor p21. While Puma deficiency increases reprogramming efficiency only in the absence of c-Myc, double deficiency of Puma and p21 has achieved a level of efficiency that exceeded that of p53 deficiency alone. We further demonstrated that, in both the presence and absence of p21, Puma deficiency was able to prevent any increase in persistent DNA damage in early iPSCs. This may be due to a compensatory cellular senescent response to reprogramming-induced DNA damage in pre-iPSCs. Therefore, our findings provide a potentially safe approach to enhance iPSC derivation by transiently silencing Puma and p21 without compromising genomic integrity.
Division of Biological Sciences, University of California, 9500 Gilman Drive, La Jolla, California, USA.
Blue B
BB
Lake
Jürgen
J
Fink
Liv
L
Klemetsaune
Xuemei
X
Fu
John R
JR
Jeffers
Gerard P
GP
Zambetti
Yang
Y
Xu
D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism*; D054337:Cell Dedifferentiation; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000235:genetics; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000235:genetics / Q000378:metabolism; D004249:DNA Damage; D020868:Gene Silencing; D006801:Humans; D000090062:Kruppel-Like Factor 4; D051379:Mice; D039904:Pluripotent Stem Cells / Q000166:cytology / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*
D051017:Apoptosis Regulatory Proteins; C493961:Cdkn1b protein, mouse; C000715467:KLF4 protein, human; C000715468:Klf4 protein, mouse; D000090062:Kruppel-Like Factor 4; C488588:PUMA protein, mouse; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27