Sequential expression of pluripotency markers during direct reprogramming of mouse somatic cells.
Pluripotency can be induced in differentiated murine and human cells by retroviral transduction of Oct4, Sox2, Klf4, and c-Myc. We have devised a reprogramming strategy in which these four transcription factors are expressed from doxycycline (dox)-inducible lentiviral vectors. Using these inducible constructs, we derived induced pluripotent stem (iPS) cells from mouse embryonic fibroblasts (MEFs) and found that transgene silencing is a prerequisite for normal cell differentiation. We have analyzed the timing of known pluripotency marker activation during mouse iPS cell derivation and observed that alkaline phosphatase (AP) was activated first, followed by stage-specific embryonic antigen 1 (SSEA1). Expression of Nanog and the endogenous Oct4 gene, marking fully reprogrammed cells, was only observed late in the process. Importantly, the virally transduced cDNAs needed to be expressed for at least 12 days in order to generate iPS cells. Our results are a step toward understanding some of the molecular events governing epigenetic reprogramming.
Brambrink
Tobias
T
Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, 9 Cambridge Center, Cambridge, MA 02142, USA.
Foreman
Ruth
R
Welstead
G Grant
GG
Lengner
Christopher J
CJ
Wernig
Marius
M
Suh
Heikyung
H
Jaenisch
Rudolf
R
D000818:Animals; D015415:Biomarkers / Q000378:metabolism*; D002454:Cell Differentiation; D002460:Cell Line; D065150:Cellular Reprogramming / Q000502:physiology*; D044127:Epigenesis, Genetic; D005347:Fibroblasts / Q000166:cytology* / Q000378:metabolism; D015967:Gene Expression Regulation, Viral; D005822:Genetic Vectors; D006801:Humans; D000090062:Kruppel-Like Factor 4; D016086:Lentivirus / Q000235:genetics*; D051379:Mice; D039904:Pluripotent Stem Cells / Q000166:cytology* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D015415:Biomarkers; C000715467:KLF4 protein, human; C000715468:Klf4 protein, mouse; D000090062:Kruppel-Like Factor 4; D014157:Transcription Factors