Post-transcription initiation function of the ubiquitous SAGA complex in tissue-specific gene activation (gene expression)

SAGA is a highly conserved transcriptional co-activator complex involved in multiple steps of transcription with activities that function both pre and post initiation. Loss of individual subunits results in developmental defects, suggesting a role in development. In particular, SAGA contains a ubiquitin protease activity involved in the transition from transcription initiation to elongation. Loss of the Sgf11 SAGA subunit causes loss of deubiquitination activity, and leads to defects in axon targeting and embryonic lethality. To better understand the roles of SAGA functions in developmental gene expression we examined its composition, binding profile, and the effects of subunit loss on gene expression in two distinct cell types in late stage Drosophila embryos: muscle and neurons. To confirm cell types, RNA from GFP labeled neuronal (elav+) or muscle (mef2+) cells isolated by FACS from late stage embryos was compared to RNA isolated from whole embryos in quadruplicate, with dye swaps as indicated. To examine the effect of subunit loss, RNA from embryonic wt and sgf11 mutant muscle cells isolated by FACS was compared in quadruplicate, with dye swaps as indicated.