Project description:Human pluripotent cells were reset to ground state pluripotency by transient overexpression of NANOG and KLF2 and subsequent inhibition of ERK and protein kinase C. Transcriptional profiling of reset cells and conventional pluripotent stem cell cultures was carried out by RNA-seq, in tandem with mouse embryonic stem cells propagated under similar conditions to assess the combinatorial effects of MEK inhibitor PD0325901, GSK3 inhibitor CHIR99021 and PKC inhibitor Go6983.
Project description:Differentiation of mammalian pluripotent cells involves large-scale changes in transcription and, among the molecules that orchestrate these changes, chromatin remodellers are essential to initiate, establish and maintain a new gene regulatory network. The NuRD complex is a highly conserved chromatin remodeller which fine-tunes gene expression in embryonic stem cells. While the function of NuRD in mouse pluripotent cells has been well defined, no study yet has defined NuRD function in human pluripotent cells. We investigated the structure and function of NuRD in human induced pluripotent stem cells (hiPSCs). Using immunoprecipitation followed by mass-spectrometry in hiPSCs and in naive or primed mouse pluripotent stem cells, we find that NuRD structure and biochemical interactors are generally conserved. Using RNA sequencing, we find that, whereas in mouse primed stem cells and in mouse naive ES cells, NuRD is required for an appropriate level of transcriptional response to differentiation signals, hiPSCs require NuRD to initiate these responses. This difference indicates that mouse and human cells interpret and respond to induction of differentiation differently.
Project description:Current human pluripotent stem cells lack the transcription factor circuitry that governs the ground state of mouse embryonic stem cells (ESC). Here we report that short-term expression of two components, NANOG and KLF2, is sufficient to ignite other elements of the network and reset the human pluripotent state. Inhibition of ERK and protein kinase C signalling sustains a transgene-independent rewired state. Reset cells self-renew continuously without ERK signalling, are phenotypically stable and karyotypically intact. They differentiate in vitro and form teratomas in vivo. Metabolism is reprogrammed in reset cells with activation of mitochondrial respiration as in ESC. DNA methylation is dramatically reduced and transcriptome state is globally realigned across multiple cell lines. Depletion of ground state transcription factors, TFCP2L1 or KLF4 has marginal impact on conventional human pluripotent stem cells, but collapses the reset state. These findings demonstrate feasibility of installing and propagating functional control circuitry for ground state pluripotency in human cells. DNA methylation analysis in Conventional and Reset human embryonic stem cells by whole genome bisulfite sequencing, in triplicate, using the Illumina platform
Project description:Mouse embryonic stem (ES) cells are isolated from the inner cell mass of blastocysts, and can be preserved in vitro in a naive inner-cell-mass-like configuration by providing exogenous stimulation with leukaemia inhibitory factor (LIF) and small molecule inhibition of ERK1/ERK2 and GSK3b signalling (termed 2i/LIF conditions). Hallmarks of naive pluripotency include driving Oct4 (also known as Pou5f1) transcription by its distal enhancer, retaining a pre-inactivation X chromosome state, global reduction in DNA methylation and in H3K27me3 repressive chromatin mark deposition on developmental regulatory gene promoters.Upon withdrawal of 2i/LIF, naM-CM-/ve mouse ES cells can drift towards a primed pluripotent state resembling that of the post-implantation epiblast. Although human ES cells share several molecular features with naive mouse ES cells, they also share a variety of epigenetic properties with primed murine epiblast stem cells (EpiSCs). These include use of the proximal enhancer element to maintain OCT4 expression, pronounced tendency for X chromosome inactivation in most female human ES cells, increase in DNA methylation and prominent deposition of H3K27me3 and bivalency acquisition on lineage regulatory genes. The feasibility for establishing human ground state naive pluripotency in vitro with equivalent molecular and functional features to those characterized in rodent ES cells remains to be defined. Here we establish defined conditions that facilitate the derivation of genetically unmodified human naive pluripotent stem cells from already established primed human ES cells, from somatic cells through induced pluripotent stem (iPS) cell reprogramming or directly from blastocysts. The novel naive pluripotent cells validated herein retain molecular characteristics and functional properties that are highly similar to mouse naive ES cells, and distinct from conventional primed human pluripotent cells. This includes competence in the generation of cross-species chimaeric embryos that underwent organogenesis following microinjection of human naive iPS cells into mouse morulas. Collectively, our findings establish new avenues for regenerative medicine, patient-specific iPS cell disease modelling and the study of early human development in vitro and in vivo. Four chromatin marks H3K4me1, H3K4me3, H3K27ac and H3K27me3 were measured from 3 cell lines: C1 and WIBR3 (naM-CM-/ve and conventional/primed stem cells), and BGO1 (only naM-CM-/ve stem cells).