KLF17 promotes human naive pluripotency through repressing MAPK3 and ZIC2

The pluripotent state of embryonic stem cells(ESCs)is regulated by a sophisticated network of transcription factors.High expression of KLF17 has recently been identified as a hallmark of naive state of human ESCs(h ESCs).However,the functional role of KLF17 in naive state is not clear.Here,by employing various gain and loss-of-function approaches,we demonstrate that KLF17 is essential for the maintenance of naive state and promotes the primed to naive state transition in h ESCs.Mechanistically,we identify MAPK3 and ZIC2 as two direct targets repressed by KLF17.Overexpression of MAPK3 or ZIC2 partially blocks KLF17 from promoting the naive pluripotency.Furthermore,we find that human and mouse homologs of KLF17 retain conserved functions in promoting naive pluripotency of both species.Finally,we show that Klf17 may be essential for early embryo development in mouse.These findings demonstrate the important and conserved function of KLF17 in promoting naive pluripotency and reveal two essential transcriptional targets of KLF17 that underlie its function.

Search for naive human pluripotent stem cells

Normal mouse pluripotent stem cells were originally derived from the inner cell mass(ICM) of blastocysts and shown to be the in vitro equivalent of those pre-implantation embryonic cells, and thus were called embryonic stem cells(ESCs). More than a decade later, pluripotent cells were isolated from the ICM of human blastocysts. Despite being called human ESCs, these cells differ significantly from mouse ESCs, including different morphology and mechanisms of control of pluripotency, suggesting distinct embryonic origins of ESCs from the two species. Subsequently, mouse pluripotent stem cells were established from the ICMderived epiblast of post-implantation embryos. These mouse epiblast stem cells(Epi SCs) are morphological and epigenetically more similar to human ESCs. This raised the question of whether cells from the human ICM are in a more advanced differentiation stage than their murine counterpart, or whether the available culture conditions were not adequate to maintain those human cells in their in vivo state, leading to a transition into Epi SC-like cells in vitro. More recently, novel culture conditions allowed the conversion of human ESCs into mouse ESC-like cells called nave(or ground state) human ESCs, and the derivation of nave human ESCs from blastocysts. Here we will review the characteristics of each type of pluripotent stem cells, how(and whether) these relate to different stages of embryonic development, and discuss the potential implications of nave human ESCs in research and therapy.

Discordance between chromatin accessibility and transcriptional activity during the human primed-to-naïve pluripotency transition process

Naive pluripotent state can be obtained by several strategies from various types of cells,in which the cell fate roadmap as well as key biological events involved in the journey have been described in detail.Here,we carefully explored the chromatin accessibility dynamics during the primed-to-naïve transition by adopting a dual fluorescent reporter system and the assay for transposase-accessible chromatin(ATAC)-seq.Our results revealed critical chromatin remodeling events and highlight the discordance between chromatin accessibility and transcriptional activity.We further demonstrate that the differential epigenetic modifications and transcription factor(TF)activities may play a critical role in regulating gene expression,and account for the observed variations in gene expression despite similar chromatin landscapes.

Multiplexed single-cell transcriptome analysis reveals molecular characteristics of monkey pluripotent stem cell lines

Efforts have been made to establish various human pluripotent stem cell lines.However,such methods have not yet been duplicated in non-human primate cells.Here,we introduce a multiplexed single-cell sequencing technique to profile the molecular features of monkey pluripotent stem cells in published culture conditions.The results demonstrate suboptimized maintenance of pluripotency and show that the selected signaling pathways for resetting human stem cells can also be interpreted for establishing monkey cell lines.Overall,this work legitimates the translation of novel human cell line culture conditions to monkey cells and provides guidance for exploring chemical cocktails for monkey stem cell line derivation.