A role for NANOG in G1 to S transition in human embryonic stem cells through direct binding of CDK6 and CDC25A

Zhang, Xin; Neganova, Irina; Przyborski, Stefan; Yang, Chunbo; Cooke, Michael J.; Atkinson, Stuart P.; Anyfantis, George; Fenyk, Stefan; Keith, W. Nicol; Hoare, Stacey F.; Hughes, Owen; Strachan, Tom; Stojković, Miodrag; Hinds, Philip W.; Armstrong, Lyle; Lako, Majlinda

doi:10.1083/jcb.200801009

Cited by 173 publications

(168 citation statements)

References 30 publications

(53 reference statements)

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“…Recent observations suggested that low levels of NANOG do not necessarily compromise pluripotency but rather increase the propensity of the cells to differentiate [29][30][31][32]. Additionally, NANOG was shown to promote phosphorylation of pRB, and thus the progression from the G1 to the S-phase in hESCs [33]. The small reduction in the levels of NANOG (but not OCT4) protein in the '40' fraction and the considerable decrease in the phosphorylation of pRB in this fraction is consistent with these previous reports.…”

Section: Discussionmentioning

confidence: 99%

Human Embryonic Stem Cells Exhibit Increased Propensity to Differentiate During the G1 Phase Prior to Phosphorylation of Retinoblastoma Protein

et al. 2012

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While experimentally induced arrest of human embryonic stem cells (hESCs) in G1 has been shown to stimulate differentiation, it remains unclear whether the unperturbed G1 phase in hESCs is causally related to differentiation. Here, we use centrifugal elutriation to isolate and investigate differentiation propensities of hESCs in different phases of their cell cycle. We found that isolated G1 cells exhibit higher differentiation propensity compared with S and G2 cells, and they differentiate at low cell densities even under self-renewing conditions. This differentiation of G1 cells was partially prevented in dense cultures of these cells and completely abrogated in coculture with S and G2 cells. However, coculturing without cell-to-cell contact did not rescue the differentiation of G1 cells. Finally, we show that the subset of G1 hESCs with reduced phosphorylation of retinoblastoma has the highest propensity to differentiate and that the differentiation is preceded by cell cycle arrest. These results provide direct evidence for increased propensity of hESCs to differentiate in G1 and suggest a role for neighboring cells in preventing differentiation of hESCs as they pass through a differentiation sensitive, G1 phase.

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Section: Discussionmentioning

confidence: 99%

Human Embryonic Stem Cells Exhibit Increased Propensity to Differentiate During the G1 Phase Prior to Phosphorylation of Retinoblastoma Protein

et al. 2012

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“…In contrast, several lines of evidence published by four independent laboratories and unpublished data from our laboratory indicate that hESCs can modify CDK activity to promote and/or inhibit cell cycle progression. These include the following: (a) cyclin quantities and CDK activities fluctuate during the cell cycle of hESCs [25,26, our unpublished data]; (b) CDK2 activity is controlled by Cdc25A [14]; (c) both hypo-and hyperphosphorylated forms of RB protein are detectable in hESCs [27, our unpublished data]; (d) miR92b regulates passage through the G1/S checkpoint by targeting the CDK inhibitor p57 [28]; and (e) regulation of the Sphase-associated CDK target, transcriptional coactivator The level of p21 protein in hESCs UVC-irradiated in G1 phase. The level of p21 was determined by western blot analysis 6 hours after irradiation (see Fig.…”

Section: Discussionmentioning

confidence: 99%

“…4B). 1145 www.StemCells.com Downregulation of Cdc25A in hESCs can be effectively achieved by siRNA [14]. Here, we used this approach to evaluate a nature and extent of the change that develops in our setting to the cell cycle progression of hESCs upon reduction of the level of Cdc25A.…”

Section: Cdc25a Not P21 Is Involved In Cdk2 Inactivation Upon Dna Dmentioning

confidence: 99%

Human Embryonic Stem Cells Are Capable of Executing G1/S Checkpoint Activation

et al. 2010

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Embryonic stem cells progress very rapidly through the cell cycle, allowing limited time for cell cycle regulatory circuits that typically function in somatic cells. Mechanisms that inhibit cell cycle progression upon DNA damage are of particular importance, as their malfunction may contribute to the genetic instability observed in human embryonic stem cells (hESCs). In this study, we exposed undifferentiated hESCs to DNA-damaging ultraviolet radiation-C range (UVC) light and examined their progression through the G1/S transition. We show that hESCs irradiated in G1 phase undergo cell cycle arrest before DNA synthesis and exhibit decreased cyclin-dependent kinase two (CDK2) activity. We also show that the phosphatase Cdc25A, which directly activates CDK2, is downregulated in irradiated hESCs through the action of the checkpoint kinases Chk1 and/or Chk2. Importantly, the classical effector of the p53-mediated pathway, protein p21, is not a regulator of G1/S progression in hESCs. Taken together, our data demonstrate that cultured undifferentiated hESCs are capable of preventing entry into Sphase by activating the G1/S checkpoint upon damage to their genetic complement.

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“…Interestingly, the CDK2 partner Cyclin A has a different role in the cell cycle of mouse somatic cells and stem cells, including ESCs 22 . Other cell cycle players, CDK6 and CDC25A, functionally interact with selfrenewal factors such as Nanog, suggesting that there is a link between the cell cycle and hESC self-renewal 23 .…”

mentioning

confidence: 99%

The RB family is required for the self-renewal and survival of human embryonic stem cells

2012

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The mechanisms ensuring the long-term self-renewal of human embryonic stem cells are still only partly understood, limiting their use in cellular therapies. Here we found that increased activity of the RB cell cycle inhibitor in human embryonic stem cells induces cell cycle arrest, differentiation and cell death. Conversely, inactivation of the entire RB family (RB, p107 and p130) in human embryonic stem cells triggers G2/M arrest and cell death through functional activation of the p53 pathway and the cell cycle inhibitor p21. Differences in E2F target gene activation upon loss of RB family function between human embryonic stem cells, mouse embryonic stem cells and human fibroblasts underscore key differences in the cell cycle regulatory networks of human embryonic stem cells. Finally, loss of RB family function promotes genomic instability in both human and mouse embryonic stem cells, uncoupling cell cycle defects from chromosomal instability. These experiments indicate that a homeostatic level of RB activity is essential for the self-renewal and the survival of human embryonic stem cells.

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A role for NANOG in G1 to S transition in human embryonic stem cells through direct binding of CDK6 and CDC25A

Cited by 173 publications

References 30 publications

Human Embryonic Stem Cells Exhibit Increased Propensity to Differentiate During the G1 Phase Prior to Phosphorylation of Retinoblastoma Protein

Human Embryonic Stem Cells Exhibit Increased Propensity to Differentiate During the G1 Phase Prior to Phosphorylation of Retinoblastoma Protein

Human Embryonic Stem Cells Are Capable of Executing G1/S Checkpoint Activation

The RB family is required for the self-renewal and survival of human embryonic stem cells

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