Mapping binding sites of SIN3 isoforms across the Drosophila genome.

SIN3 associates with RPD3 and other accessory proteins to form the SIN3 histone modifying complex. A single Sin3A gene encodes multiple SIN3 isoforms, of which SIN3 187 and SIN3 220 are predominant. Previous studies from our laboratory and others have indicated that SIN3 isoforms play non-redundant roles during fly development, however, the genes regulated by SIN3 isoforms are not known. We mapped the genome-wide binding sites of SIN3 isoforms in Drosophila. We established stable S2 cell lines that express either HA-tagged SIN3 187 or SIN3 220. The binding profiles revealed that the majority of the binding sites of SIN3 isoforms are overlapping. Our data revealed that SIN3 isoforms localize to euchromatic regions of the genome and enrichment of SIN3 isoforms are generally concentrated around the transcription start sites of genes. In addition, the extent of SIN3 binding confirmed previous findings indicating that SIN3 is a global transcriptional regulator. Overall design: Genome-wide binding analysis of SIN3 187 and SIN3 220 in Drosophila. Using chromatin prepared from cell lines expressing either of the isoforms, we performed chromatin immunoprecipitation on chromatin prepared from cells that expresses either of the isoforms using an antibody against HA (ChIP). We coupled our ChIP with high resolution deep sequencing (ChIP-seq) to identify genomic targets of SIN3 isoforms.