Skip to main page content
U.S. flag

An official website of the United States government

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2020 Oct 8;23(11):101646.
doi: 10.1016/j.isci.2020.101646. eCollection 2020 Nov 20.

Cell Signaling Coordinates Global PRC2 Recruitment and Developmental Gene Expression in Murine Embryonic Stem Cells

Mohammad B Aljazi  1 , Yuen Gao  1 , Yan Wu  1 , George I Mias  1   2 , Jin He  1
Affiliations

Cell Signaling Coordinates Global PRC2 Recruitment and Developmental Gene Expression in Murine Embryonic Stem Cells

Mohammad B Aljazi et al. iScience. .

Abstract

The recruitment of Polycomb repressive complex 2 (PRC2) to gene promoters is critical for its function in repressing gene expression in murine embryonic stem cells (mESCs). However, previous studies have demonstrated that although the expression of early lineage-specific genes is largely repressed, the genome-wide PRC2 occupancy is unexpectedly reduced in naive mESCs. In this study, we provide evidence that fibroblast growth factor/extracellular signal-regulated kinase signaling determines the global PRC2 occupancy through regulating the expression of PRC2-recruiting factor JARID2 in naive mESCs. At the transcriptional level, the de-repression of bivalent genes is predominantly determined by the presence of cell signaling-associated transcription factors but not the status of PRC2 occupancy at gene promoters. Hence, this study not only reveals a key molecular mechanism by which cell signaling regulates the PRC2 occupancy in mESCs but also elucidates the functional roles of transcription factors and Polycomb-mediated epigenetic mechanisms in transcriptional regulation.

Keywords: Cell Biology; Developmental Biology; Molecular Biology; Stem Cells Research.

PubMed Disclaimer

Conflict of interest statement

Authors declare no competing interests.

Figures

None
Graphical abstract
Figure 1
Figure 1
Jarid2 Expression Is Significantly Reduced in naive mESC (A) Heatmap showing the expression of PRC2 core and PRC2.1-/PRC2.2-specific genes analyzed by RNA-seq. (B) qRT-PCR analysis showing the expression levels of PRC2 core, PRC2.1-/PRC2.2-specific genes, and ncPRC1.1 genes in mESC-S and mESC-2i. The results were normalized against levels of Gapdh, and the expression level in mESC-S was arbitrarily set to 1. The error bars represent the standard deviation (n = 3). (C) Western blot analysis showing the protein levels of PRC2 core and PRC2.1-/PRC2.2-specific components. (D) Heatmap showing the expression of ncPRC1.1 genes analyzed by RNA-seq. (E) Western blot analysis showing the protein levels of ncPRC1.1 components.
Figure 2
Figure 2
FGF/ERK Signaling Positively Regulates Jarid2 Expression in mESCs (A) Schematic chart showing the experimental design for the analysis of gene expression in response to the re-activation of FGF/ERK signaling. (B) Western blot analysis showing phosphorylated p42/44 ERKs were increased in response to the re-activation of FGF/ERK signaling. (C) Heatmap showing the expression of PRC2 core and PRC2.1-/PRC2.2-specific genes in response to the re-activation of FGF/ERK signaling. (D) Western blot analysis showing the protein levels of PRC2 core and PRC2.1-/PRC2.2-specific components in mESCs in response to the re-activation of FGF/ERK signaling.
Figure 3
Figure 3
Knockout of Erk1/Erk2 Reduces Jarid2 Expression in mESCs (A) Western blot analysis showing p42/44 ERKs, ectopically expressed wild-type ERK2-HA, and JARID2 proteins in wild-type, Erk1/Erk2-dKO, and Erk1/Erk2-dKO rescued with wild-type ERK2-HA (Erk1/Erk2-dKO + Erk2-HA) mESCs. (B) Heatmap showing the expression of Polycomb core genes in wild-type, Erk1/Erk2-dKO, and Erk1/Erk2-dKO + Erk2-HA mESCs. (C) IGV genome browser view of Jarid2 expression in wild-type, Erk1/Erk2-dKO, and Erk1/Erk2-dKO rescued with wild-type ERK2-HA mESCs. (D) qRT-PCR analysis showing the Jarid2 expression in wild-type, Erk1/Erk2-dKO, and Erk1/Erk2-dKO rescued with wild-type ERK2-HA mESCs. The results were normalized against levels of Gapdh, and the expression level in wild-type mESCs was arbitrarily set to 1. The error bars represent standard deviation (n = 3).
Figure 4
Figure 4
The Global PRC2 Occupancy at CGIs Is Largely Reduced in naive mESCs (A–D) Plot (upper) and heatmap (bottom) showing EZH2 occupancy, histone H3K27me3 modification, JARID2 occupancy, and KDM2B occupancy at CGIs and 10-kb CGI-flanking regions in mESC-S and mESC-2i. (E) IGV genome browser view of EZH2, JARID2, KDM2B occupancy, and histone H3K27me3 modification at the representative Hoxa gene cluster (left panel), Gata6 (middle panel), and Sox17 (right panel) in mESC-S and mESC-2i.
Figure 5
Figure 5
Ectopic Expression of Jarid2 Restores the Global PRC2 Occupancy in naive mESCs (A–C) Plot (upper) and heatmap (bottom) showing JARID2 occupancy, EZH2 occupancy, and histone H3K27me3 modification at CGIs and 10-kb CGI-flanking regions in mESC-S (serum), mESC-2i (2i), and mESC-2i with ectopically expressed Jarid2 (2i + Jarid2). (D) IGV genome browser view of EZH2 and histone H3K27me3 modification at the representative Hoxa gene cluster (left panel), Gata6 (middle panel), and Sox17 (right panel) in mESC-S (serum), mESC-2i (2i), and mESC-2i with ectopically expressed Jarid2 (2i + Jarid2).
Figure 6
Figure 6
Ectopic Expression of Erk2 or Jarid2 Restores the Global PRC2 Occupancy in Erk1/Erk2-dKO mESCs (A–C) Plot (upper) and heatmap (bottom) showing JARID2 occupancy, EZH2 occupancy, and histone H3K27me3 modification at CGIs and 10-kb CGI-flanking regions in wild-type, Erk1/Erk2-dKO, and Erk1/Erk2-dKO rescued with wild-type Erk2 (Erk1/Erk2-dKO + Erk2) mESCs. (D–F) Plot (upper) and heatmap (bottom) showing JARID2 occupancy, EZH2 occupancy, and histone H3K27me3 modification at CGIs and 10-kb CGI-flanking regions in wild-type, Erk1/Erk2-dKO, and Erk1/Erk2-dKO with ectopically expressed Jarid2 (Erk1/Erk2-dKO + Jarid2) mESCs.
Figure 7
Figure 7
Activation of Bivalent Genes Is Determined by the Presence of Signaling-Associated Transcription Factors but Not the Status of PRC2 Occupancy in naive mESCs (A) Plot showing 253 upregulated and 589 downregulated bivalent genes in mESC-2i compared to mESC-S. (B) Heatmap showing the expression of representative primitive endoderm-specific genes in mESC-S and mESC-2i. (C) Heatmap showing 136 bivalent genes de-repressed in mESC-2i and re-silenced after inactivation of Wnt/β-catenin signaling (mESC-PD). (D) Heatmap showing the representative Wnt/β-catenin direct target genes de-repressed in mESC-2i and re-silenced after inactivation of Wnt/β-catenin signaling (mESC-PD). (E) Plot showing EZH2 occupancy, JARID2 occupancy, histone H3K27me3 modification, and β-CATENIN occupancy at 136 Wnt/β-catenin signaling target genes in mESC-S, mESC-2i, and mESC-PD. TSS: transcription starting sites; TES: transcription ending sites. (F) IGV genome browser view of EZH2 occupancy, histone H3K27me3 modification, β-CATENIN occupancy, and gene expression of representative Wnt/β-catenin signaling direct target genes Axin2, T, and Cdx2 in mESC-S, mESC-2i, and mESC-PD.
Figure 8
Figure 8
Proposed Model: Cell Signaling Coordinates PRC2 Recruitment and Developmental Gene Expression in mESCs In serum-containing medium, FGF/ERK signaling increases both Jarid2 expression and JARID2-mediated PRC2 recruitment to bivalent promoters, which increases the thresholds for transcriptional activation and prevents stochastic expression of FGF signaling target genes (upper panel). In 2i medium, the deficient FGF/ERK signaling decreases the Jarid2 expression and JARID2-mediated PRC2 recruitment to bivalent promoters, which reduces the thresholds for transcriptional activation. In the absence of FGF/ERK signaling-associated transcriptional factors, the FGF/ERK signaling target genes remain silenced. In contrast, the activated Wnt/β-catenin signaling and its transcription factor β-CATENIN (β-CAT) activate the Wnt signaling target genes (lower panel).
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Al-Raawi D., Jones R., Wijesinghe S., Halsall J., Petric M., Roberts S., Hotchin N.A., Kanhere A. A novel form of JARID2 is required for differentiation in lineage-committed cells. EMBO J. 2019;38:e98449. - PMC - PubMed
    1. Aloia L., Di Stefano B., Di Croce L. Polycomb complexes in stem cells and embryonic development. Development. 2013;140:2525–2534. - PubMed
    1. Blackledge N.P., Fursova N.A., Kelley J.R., Huseyin M.K., Feldmann A., Klose R.J. PRC1 catalytic activity is central to polycomb system function. Mol. Cell. 2019;77:857–874.e9. - PMC - PubMed
    1. Blackledge N.P., Zhou J.C., Tolstorukov M.Y., Farcas A.M., Park P.J., Klose R.J. CpG islands recruit a histone H3 lysine 36 demethylase. Mol. Cell. 2010;38:179–190. - PMC - PubMed
    1. Boyer L.A., Plath K., Zeitlinger J., Brambrink T., Medeiros L.A., Lee T.I., Levine S.S., Wernig M., Tajonar A., Ray M.K. Polycomb complexes repress developmental regulators in murine embryonic stem cells. Nature. 2006;441:349–353. - PubMed