The Drosophila histone variant H2Av facilitates Notch signaling activity in a two-tier regulatory fashion
Background H2Av is evolutionarily conserved H2A variant protein involved in the regulation of transcription. The Tip60 complex is recruited by different transcription factors to facilitate the incorporation and acetylation of H2Av, thereby influencing target gene expression by modifying the stability of the nucleosome that occludes the transcription start site. The Tip60-H2Av module is involved in various developmental processes, though its precise roles are not yet fully understood. Methods RNA interference and gene knock-out technology were used screen essential genes in regulating Notch signaling pathway. We use immunostaining method to detect the protein level of H2Av, Tip60 complex as well as Notch signaling pathway components. Chromatin immunoprecipitation assay was performed to detect the specific bind of H2Av in E(spl)-Complex and Su(H) genes. Result Here we report that H2Av is required for Notch signaling activation during Drosophila wing development. H2Av depletion disrupts the expression of Notch target genes, resulting in wing marginal defects. Unexpectedly, we find that H2Av regulates the expression of Su(H) gene which encodes the transcription factor of the Notch signaling cascade. We further demonstrate that the Tip60 complex modulates the transcription of both Notch targets and Su(H) likely through H2Av. Based on these observations, we propose a model that the Tip60-H2Av module facilitates Notch pathway activation by simultaneously promoting the expression of both the target genes and the transcription factor. Conclusion This study offers insights into the diverse roles of the Tip60-H2Av module in Notch pathway activation by identifying a novel two-tier regulatory mechanism which may also be utilized by other chromatin remodeling factors. Key words H2Av, Notch, Su(H), Drosophila, Tip60 Overall design: Collect ChIP-seq sequencing experiments on the disc tissues of H2Av-EGFP strains with endogenous GFP knock in from winged adults.