Deterministic Restriction on Pluripotent State Dissolution by Cell-Cycle Pathways

Abstract

During differentiation, human embryonic stem cells (hESCs) shut down the regulatory network conferring pluripotency in a process we designated pluripotent state dissolution (PSD). In a high-throughput RNAi screen using an inclusive set of differentiation conditions, we identify centrally important and context-dependent processes regulating PSD in hESCs, including histone acetylation, chromatin remodeling, RNA splicing, and signaling pathways. Strikingly, we detected a strong and specific enrichment of cell-cycle genes involved in DNA replication and G2 phase progression. Genetic and chemical perturbation studies demonstrate that the S and G2 phases attenuate PSD because they possess an intrinsic propensity toward the pluripotent state that is independent of G1 phase. Our data therefore functionally establish that pluripotency control is hardwired to the cell-cycle machinery, where S and G2 phase-specific pathways deterministically restrict PSD, whereas the absence of such pathways in G1 phase potentially permits the initiation of differentiation.

Cycling through developmental decisions: how cell cycle dynamics control pluripotency, differentiation and reprogramming

“…A recent study has revealed another interesting connection between exit from pluripotency and early cell fate decisions, this time involving S phase and G2 phase. In this study, a high-throughput RNA interference (RNAi) screen performed in human embryonic stem cells (hESCs) identified cell cycle genes involved in DNA replication and G2-phase progression that restrict exit from pluripotency or 'pluripotent state dissolution' (Gonzales et al, 2015). This is another line of evidence that supports the idea that the cell cycle state of PSCs is related to maintenance of pluripotency.…”

Accelerated Senescence of Cancer Stem Cells: A Failure to Thrive or a Route to Survival?

“…In accordance with our indings in PA1 cells after ETO treatment, a recent high-throughput RNAi screen revealed the intrinsic roles of S and G2, functionally establishing that pluripotency control is hardwired to the cell-cycle machinery and that the ATM/ATR-CHEK2-p53 axis enhances the TGF-b pathway to prevent premature cell death [36]. As well, [3] showed that cellular senescence accompanying DNA damage or DNA damage as such favors cell reprogramming in vivo models.…”

“…Therefore, damaged ESC cells typically accumulate in the G2 DNA damage checkpoint instead, whose relative weakness allows mitotic slippage [35,36]. Moreover, stressed ESC and likely also CSC possess a peculiar intermediate post-slippage phase (not 4 N-G1) [37,38] containing non-degraded cyclin B1, which is normally destroyed after mitosis.…”

Bam and Otu can regulate stem cell fate by stabilizing cyclin A

“…In Drosophila female GSCs, the G1 phase is also short and most of the cell cycle is spent in G2 (18). In addition, recent work in human embryonic stem cells shows that the maintenance of their pluripotency is actively controlled in S and G2 phases, through the ATM and Cyclin B1 pathways (20). Because Drosophila GSCs exhibit an extended G2 phase, their self-renewal ability could similarly be maintained during this phase.…”