Regulation of Spermatogenesis by the BTB Transcription Factor Ribbon

The transcription factor Ribbon (Rib) plays an essential role in Drosophila testis development and function. Increased expression of rib throughout development results in significant morphology defects in the adult testis. If overexpression is limited to germ cells and somatic cells in the adult, more mild defects are observed. To better understand how Rib regulates spermatogenesis, we are interested in identifying its transcriptional targets in this context. Through bulk RNA sequencing, differential expression analysis, and subsequent filtering of results, we identified 301 genes with significant changes in expression when rib was overexpressed. Given the previously described role of Rib in the regulation of cell morphogenesis and cell-cell interactions during development, we were particularly interested in genes involved in cell adhesion and regulation of the cytoskeleton. Therefore, of these 301 potential Rib targets, approximately 10 genes of interest were selected for additional analysis due to their implications in cell adhesion or the cytoskeleton. At this time, we have confirmed that shortstop (shot), which encodes a cytoskeletal linker protein, and rhea, which is critical to cell-cell adhesion, are regulated by Rib, revealing that Rib may regulate spermatogenesis through control of the cytoskeleton and adhesion. Current evidence strongly suggests that Rib regulates spermatogenesis by controlling the expression levels of genes involved in the regulation of cell morphology.