Kinome-Wide RNAi Screen Uncovers Role of Ballchen in Maintenance of Gene Activation by Trithorax Group in Drosophila

Polycomb group (PcG) and trithorax (trxG) proteins are evolutionary conserved factors that contribute to cell fate determination maintenance of cellular identities during development multicellular organisms. The PcG maintains heritable patterns gene silencing while trxG acts as anti-silencing by conserving activation type specific genes. Genetic molecular analysis has revealed extensive details about how different complexes antagonize each other maintain fates, however, the signaling components preservation expression PcG/trxG remain elusive. Here, we report an ex vivo kinome-wide RNAi screen in Drosophila aimed at identifying genes facilitate counteracting mediated repression. From list candidates, Ballchen (BALL), a histone kinase known phosphorylate H2A threonine 119 (H2AT119p), was characterized regulator. ball mutant exhibits strong genetic interactions with ( Pc ) trx mutants loss BALL affects target co-localizes Trithorax on chromatin depletion results increased H2AK118 ubiquitination, mark central silencing. Moreover, found substantially associate TRX binding sites across genome. Genome wide distribution also overlaps H3K4me3 H3K27ac actively transcribed We propose positively contributes repressive effect PcG.