Study : Diurnal regulation of SDG2 and JMJ14 by circadian clock oscillators orchestrates histone modification rhythms in Arabidopsis
Diurnal regulation of SDG2 and JMJ14 by circadian clock oscillators orchestrates histone modification rhythms in Arabidopsis
Circadian rhythms modulate physiological and developmental processes in all organisms through interlocking transcriptional-translational feedback loops. The transcriptional loop involves chromatin modifications of the central circadian oscillators in mammals and plants. However, the molecular basis for rhythmic epigenetic modifications and circadian regulation remains poorly understood. Here we report an interplay between histone modifications and circadian regulation in Arabidopsis. Diurnal rhythms of H3K9ac and H3K4me3 are associated with diurnal regulation of 20-30% of the expressed genes, respectively. While the majority (86%) of all H3K9ac and H3K4me3 target genes overlapped, only 13% of morning-phased and 22% of evening-phased genes had both H3K4me3 and H3K9ac peaks, suggesting a specificity of histone modifications for circadian gene expression. Significantly, the H3K4me3 methyltransferase SDG2 and demethylase JMJ14 genes were subjected to the circadian clock regulation; likewise the expression of the circadian clock genes was reciprocally regulated by the H3K4me3 writer (SDG2) and eraser (JMJ14). The results provide novel insights into a feedback module between chromatin modifiers and circadian clock regulators to orchestrate circadian-mediated gene expression and development.