The POU transcription factor Oct-4 is essential for the pluripotent character of the mouse inner cell mass (ICM) and derivative embryonic stem (ES) cells. We analyzed the expression of Oct-4 during culture and establishment of cell lines from mouse and rat preimplantation embryos. Oct-4 was rapidly lost in primary outgrowths of the majority of cultured embryos prior to any evidence of morphological differentiation. Oct-4 persisted in only a minority of strain 129 cultures, which can go on to give ES cells. We used transgenic rats in which the dual reporter/selection marker β-geo is under control of Oct-4 regulatory elements to investigate the effect of direct selection for Oct-4 expressing cells. Ablation of all cells occurred, consistent with complete downregulation of Oct-4. Without selection, in contrast, continuous cultures of morphologically undifferentiated cells could be derived readily from rat blastocysts and ICMs. However, these cells did not express significant Oct-4 and, although capable of differentiating into extraembryonic cell types, appeared incapable of producing fetal germ layer derivatives. Downregulation of Oct-4 appears to be a limiting factor in attempts to derive pluripotent cell lines from preimplantation embryos.
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1 January 2003
Rapid Loss of Oct-4 and Pluripotency in Cultured Rodent Blastocysts and Derivative Cell Lines
M. Buehr,
J. Nichols,
F. Stenhouse,
P. Mountford,
C. J. Greenhalgh,
S. Kantachuvesiri,
G. Brooker,
J. Mullins,
A. G. Smith
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developmental biology
early development
embryo
gene regulation