Abstract
p300 is a well known histone acetyltransferase and coactivator that plays pivotal roles in many physiological processes. Despite extensive research for the functions of p300 in embryogenesis and transcription regulation, its roles in regulating embryonic stem (ES) cell pluripotency are poorly understood. To address this issue, we investigated the self-renewal ability and early differentiation process in both wild-type mouse ES cells and ES cells derived from p300 knock-out (p300(-/-)) mice. We found that p300 ablation did not affect self-renewal capacity overtly when ES cells were maintained under undifferentiated conditions. However, the absence of p300 caused a significantly abnormal expression pattern of germ layer markers when differentiation was induced by embryoid body (EB) formation. Interestingly, the expression level of pluripotency marker Nanog but not Oct4 was markedly lower in EBs from p300(-/-) ES cells compared with that in EBs from wild-type ES cells. Exogenous expression of Nanog rescued abnormal expression of extra-embryonic endoderm marker partially but not mesoderm and ectoderm markers. Furthermore, we demonstrate that p300 was directly involved in modulating Nanog expression. Importantly, epigenetic modification of histone acetylation at the distal regulatory region of Nanog was found to be dependent on the presence of p300, which could contribute to the mechanism of regulating Nanog expression by p300. Collectively, our results show that p300 plays an important role in the differentiation process of ES cells and provide the first evidence for the involvement of p300 in regulating Nanog expression during differentiation, probably through epigenetic modification of histone on Nanog.
Highlights
Mouse embryonic stem (ES)2 cells are self-renewing and pluripotent cell lines derived from the inner cell mass of the blastocyst of preimplantation embryos
The results demonstrate that p300 is required for ES cells to undergo early differentiation appropriately, partially through its positively regulatory effect on Nanog expression
We found that embryoid body (EB) formed from p300Ϫ/Ϫ ES cells were smaller during the first 2 or 3 days, as had been reported by other researchers [16, 22]
Summary
Mouse embryonic stem (ES)2 cells are self-renewing and pluripotent cell lines derived from the inner cell mass of the blastocyst of preimplantation embryos. With transcription factor Sox2, Oct4 activates expression of genes promoting self-renewal and pluripotency of ES cells but suppresses genes associated with differentiation [2, 3].
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