GSE64600
SUVH1, a histone methyltransferase, is required for the expression of genes targeted by DNA methylation
Transposons and repeats are found throughout the genomes of all organisms. To prevent the harmful effects of these elements, repressive marks such as DNA methylation and H3K9me2 have evolved to control transposon activity and ultimately maintain genome integrity. However, how silencing mechanisms are themselves regulated to avoid stochastic silencing of genes remains unclear. Here, negative regulators of silencing were identified using a forward-genetic screen on a reporter line that harbors a LUCIFERASE (LUC) gene driven by a double 35S promoter. SUVH1, a SU(VAR)3-9 homolog, was isolated as a factor promoting the expression of the LUC gene. Treatment with a cytosine methylation inhibitor compromised the effect of the identified suvh1 mutation, indicating that SUVH1 is dispensable for LUC expression in the absence of DNA methylation. However, the suvh1 mutation did not alter DNA methylation levels at the LUC region or on a genome-wide scale; thus, SUVH1 may function downstream of DNA methylation. Histone methylation analysis revealed that suvh1 led to decreased H3K4me3 levels; in contrast, H3K9me2 levels remained unchanged. Moreover, the characterization of endogenous genes indicated that SUVH1 functions at genes with repressive marks in the promoter region. Taken together, these findings shed light on the regulatory network acting at genes with various epigenetic marks. Overall design: The BS-seq and mRNA-seq were performed on the reporter line YJ and the mutant YJ suvh1 to assess the effect on DNA methylation and transcriptome caused by suvh1 mutation