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DNA microarray analysis of Jmjd1a and/or Jmjd1b knockout embryonic stem cells

ABSTRACT: Histone H3 lysine 9 (H3K9) methylation is an epigenetic mark of transcriptionally repressed chromatin. During mammalian development, H3K9 methylation levels seem to be spatiotemporally regulated by the opposing activities of methyltransferases and demethylases to govern correct gene expression. However, the combination(s) of H3K9 methyltransferase(s) and demethylase(s) that contribute to this regulation and the genes regulated by them remain unclear. Herein, we demonstrate the essential roles of H3K9 demethylases Jmjd1a and Jmjd1b in the embryogenesis and viability control of embryonic stem (ES) cells. Mouse embryos lacking Jmjd1a/Jmjd1b died after implantation. Depletion of Jmjd1a/Jmjd1b in mouse ES cells induced rapid cell death accompanied with a massive increase in H3K9 methylation. Jmjd1a/Jmjd1b depletion induced an increase in H3K9 methylation in the gene-rich regions of the chromosomes, indicating that Jmjd1a/Jmjd1b removes H3K9 methylation marks in the euchromatin. Importantly, the additional disruption of the H3K9 methyltransferase G9a in a Jmjd1a/Jmjd1b-deficient background rescued not only the H3K9 hypermethylation phenotype but also the cell death phenotype. We also found that Jmjd1a/Jmjd1b removes H3K9 methylation marks deposited by G9a in the Oct4 and Ccnd1 loci to activate transcription. In conclusion, Jmjd1a/Jmjd1b ensures ES cell viability by antagonizing G9a-mediated H3K9 hypermethylation in the gene-rich euchromatin.

ORGANISM(S): Mus musculus

PROVIDER: GSE98761 | GEO | 2018/03/14

REPOSITORIES: GEO

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Project description:Hypoxia is one of the major driving forces mediating tumor angiogenesis, aggressiveness, as well as resistance to chemo- and radiotherapy. It has also been suggested to play important roles in stem cell maintenance for both normal and cancer tissues. However, the mechanisms by which hypoxia-driven epigenetic changes modulate tumorigenesis remain poorly understood. As the histone H3 lysine 9 (H3K9) demethylase Jmjd1a and methyltransferase G9a are upregulated downstream targets of hypoxia, we focused on these two catalytically opposing epigenetic modifiers to address this question. Through the use of homozygous Jmjd1a and G9a knockout mouse embryonic stem (ES) cells, we found that Jmjd1a was not required for stem cell self-renewal and that anti-angiogenesis related genes were epigenetically dysregulated in both Jmjd1a- and G9a deficient ES cells under hypoxic conditions, accompanied by corresponding changes in H3K9 dimethylation and H3K4 trimethylation levels in the proximal promoter regions of these target genes. Most importantly, these genetic alterations led to opposing tumor phenotypes: loss of Jmjd1a results in increased tumor growth, whereas loss of G9a produces smaller tumors. These findings provide new insights on the importance of hypoxia signalling in regulating the epigenetic status and expression of angiogenesis genes that promote tumor progression. 63 microarray samples consisting of 7 mouse ES cell lines of which 2 are wild type (control), 2 Jmjd1a knockout, 2 G9a knockout and 1 G9a knockout that was reconstituted for G9a (G9a control). Each cell line and condition was seeded at 3 different densities (2X10^5, 4X10^5 and 6X10^5) in 6 cm dishes to control for the effects of cell confluency on gene expression. 18 hours after plating, the cells were subjected to normoxia (21% O2) for 24 hours (control), normoxia 20 hours followed by hypoxia (1% O2) for 4 hours (acute hypoxia) and 24 hours hypoxia (chronic treatment). Total RNA was harvested from all samples for microarrays after the 24 hour treatments.

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DNA microarray analysis of Jmjd1a and/or Jmjd1b knockout embryonic stem cells

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