Dynamic association of MLL1, H3K4 trimethylation with chromatin and Hox gene expression during the cell cycle

摘要: Mixed lineage leukemias (MLLs) are histone H3 at lysine 4 (H3K4)-specific methylases that play a critical role in regulating gene expression humans. As chromatin condensation, relaxation and differential keys to correct cell cycle progression, we analyzed the dynamic association of MLL H3K4 trimethylation different stages cycle. Interestingly, MLL1, which is normally associated with transcriptionally active chromatins (G1 phase), dissociates from condensed mitotic returns end telophase when nucleus starts relax. In contrast, mark, also euchromatins (in G1), remains associated, even chromatin, throughout The global levels MLL1 not affected during cycle, H3Ser28 phosphorylation only observed mitosis. target homeobox-containing (Hox) genes (HoxA5, HoxA7 HoxA10) differentially expressed recruitment modulated promoter these Hox as function their expression. addition, down-regulation results arrest G2/M phase. fluctuation marks specific promoters, but level, indicates present G1 phase may be same other phases cycle; rather, old removed new introduced. conclusion, our studies demonstrate methylation have distinct dynamics roles regulation.