ChIP Seq of Oct4, Nanog, H3K27me3 in Oct4+/+ and Oct4 +/- mES cells
Embryonic stem cell (ESC) pluripotency is governed by a gene regulatory network centred on the transcription factors Oct4 and Nanog. ESCs fluctuate between states of high and low Nanog expression that direct efficient or inefficient self-renewal. To date, robust self-renewing ESC states have only been attained by chemical inhibition of signalling pathways or enforced transgene expression. Here we show that ESCs expressing a reduced range of Oct4 concentrations, typified by Oct4 heterozygous ESCs exhibit stable robust pluripotency. Despite this reduced Oct4 concentration range, this state is characterised by increased genome-wide binding of Oct4, particularly at pluripotency-associated enhancers, homogeneous expression of pluripotency transcription factors, enhanced self-renewal efficiency and delayed differentiation kinetics. In this state, ESCs exhibit increased wnt expression, enhanced LIF-sensitivity, non-responsiveness to FGF signalling and can clonally maintain pluripotency without BMP but remain dependent upon LIF. Robust pluripotency is destabilised either by alteration of the Oct4 level or by removal of LIF. Our findings suggest that robust pluripotency originates from cells with a reduced Oct4 protein concentration and that the wild-type Oct4 range enables effective differentiation.