Initiation of stem cell differentiation involves cell cycle-dependent regulation of developmental genes by Cyclin D

Abstract

Coordination of differentiation and cell cycle progression represents an essential process for embryonic development and adult tissue homeostasis. These mechanisms ultimately determine the quantities of specific cell types that are generated. Despite their importance, the precise molecular interplays between cell cycle machinery and master regulators of cell fate choice remain to be fully uncovered. Here, we demonstrate that cell cycle regulators Cyclin D1-3 control cell fate decisions in human pluripotent stem cells by recruiting transcriptional corepressors and coactivator complexes onto neuroectoderm, mesoderm, and endoderm genes. This activity results in blocking the core transcriptional network necessary for endoderm specification while promoting neuroectoderm factors. The genomic location of Cyclin Ds is determined by their interactions with the transcription factors SP1 and E2Fs, which result in the assembly of cell cycle-controlled transcriptional complexes. These results reveal how the cell cycle orchestrates transcriptional networks and epigenetic modifiers to instruct cell fate decisions.

Optimized inducible shRNA and CRISPR/Cas9 platforms for in vitro studies of human development using hPSCs

“…3G), whereas triple knockdown resulted in definitive endoderm differentiation (Fig. 3G,H), as previously reported (Pauklin and Vallier, 2013; Pauklin et al, 2016). Collectively, these results demonstrate that sOPTiKD can be used to simultaneously decrease the expression of several genes with redundant functions.…”

Full biological characterization of human pluripotent stem cells will open the door to translational research

“…Interestingly, induction of endoderm differentiation in early G1 is regulated by transcriptional activity of the activin/nodal-Smad2/3 signaling cascade, when cyclin D expression is limited, whereas high expression of cyclin D in late G1-phase can inhibit activin/ nodal signaling for directing differentiation toward the neuroectodermal lineage. This is achieved by interaction and recruitment of cyclin D with transcriptional corepressors to endoderm loci and with coactivators to genes for neuroectodermal differentiation (Pauklin et al 2016). Similar results were obtained upon treatment of hESC with the Wnt ligand Wnt3a.…”

A role for mitotic bookmarking of SOX2 in pluripotency and differentiation

“…The most striking impact on cell fate decisions that we observed was the abrogation of the neuroectodermal differentiation-promoting activity of SOX2 when absent at the M-G1 transition. In ES cells, the decisions to commit to the mesendodermal versus neuroectodermal lineages take place in early and late G1, respectively (Pauklin and Vallier 2013), and are regulated notably by the cell cycle machinery (Pauklin et al 2016). In our experiments with dox-inducible SOX2-MD, expression levels increase rapidly after cell division, and thus the absence of neuroectodermal fate enhancement is unlikely to result from insufficient expression at the end of the G1 phase but rather suggests that SOX2 acts during the M-G1 transition to enhance neuroectodermal commitment.…”