Expression profiling by high throughput sequencing Genome binding/occupancy profiling by high throughput sequencing
Summary
We use ChIP-Seq and RNA-Seq technology to profile the H3K9me2 modification and transcription under different conditions of GLP activity. GLP and G9a are major H3K9 dimethylases, and are essential for mouse early embryonic development. Here we report that GLP and G9a possess intrinsic histone methylation propagating activities. The histone methyltransferase activities of GLP and G9a are stimulated by neighboring nucleosomes pre-methylated at H3K9. These stimulation events function in cis and are dependent on H3K9 methylation binding activities of ankyrin repeats domains in GLP and G9a. In mouse embryonic stem cells (ESCs) harboring a mutant GLP lacking H3K9 methylation propagating activity, pluripotent genes display a delayed kinetics in establishing H3K9 methylation and gene silencing during differentiation. Disruption of the H3K9 methylation propagating activity of GLP in mice causes growth retardation of the embryos, ossification defects of calvaria and early postnatal lethality. We propose that GLP¡¯s ability to rapidly propagate H3K9 methylation is required for efficient gene silencing during programmed cell fate transition.
Overall design
H3K9me2 and H3K9me1 are ChIPped and sequenced in WT mESC and GLP-mutant mESCs, and RNA-Seq was done for those cells as well. ChIP-seq for H3K9me2 was also performed in wildtype and mutant newborn mouse liver.