Jarid2 Methylation via the PRC2 Complex Regulates H3K27me3 Deposition during Cell Differentiation.
Bottom Line: This modification is recognized by the Eed core component of PRC2 and triggers an allosteric activation of PRC2's enzymatic activity.We show that Jarid2 methylation is important to promote PRC2 activity at a locus devoid of H3K27me3 and for the correct deposition of this mark during cell differentiation.Our results uncover a regulation loop where Jarid2 methylation fine-tunes PRC2 activity depending on the chromatin context.
Affiliation: Institut Curie, 26 Rue d'Ulm, 75005 Paris, France; INSERM U934, 26 Rue d'Ulm, 75005 Paris, France; CNRS UMR3215, 26 Rue d'Ulm, 75005 Paris, France.Show MeSH
Related in: MedlinePlus
Mentions: The results presented so far demonstrate that Jarid2 methylation is important for PRC2 activity in vitro and when artificially tethered to chromatin in a cellular context. To confirm the biological relevance of this regulation, we evaluated the function of Jarid2 methylation in ESC. We used ESC KO for Jarid2 (Shen et al., 2009) and generated cell lines rescued with either WT or K116A mutant forms of Jarid2. Since Jarid2 is dynamically regulated during cell differentiation, the rescues were performed using bacterial artificial chromosomes (BACs) in order to recapitulate the endogenous expression of the Jarid2 gene. Rescued ESC lines expressed Jarid2 homogeneously, with appropriate nuclear distributions as illustrated by IF (Figure 6A) and at similar levels as shown by western blot (Figure 6B). Moreover, all three lines exhibited similar global levels of H3K27me3 and Oct4 protein (Figure 6B). Interestingly, Jarid2 WT rescued ESC presented slight morphological differences, displaying more typical ESC colonies, when compared to Jarid2 KO or K116A mutant cells that tend to show a more flattened morphology (Figure 6C, left). They also formed fewer colonies when plated at low density as compared to the K116A rescued line (Figure 6C, right). Nonetheless, all the three ESC lines showed similar levels of alkaline phosphatase activity, comparable proliferation rates, and no major differences in gene expression (Figure 6D and day 0 in Figure 6F), thus confirming that Jarid2 is not necessary for ESC pluripotency and self-renewal (Landeira et al., 2010; Shen et al., 2009).
Affiliation: Institut Curie, 26 Rue d'Ulm, 75005 Paris, France; INSERM U934, 26 Rue d'Ulm, 75005 Paris, France; CNRS UMR3215, 26 Rue d'Ulm, 75005 Paris, France.