Transcriptional Profiling of Class IV da Neurons

Elucidating the molecular mechanisms controlling dendrite development is key to understanding the pivotal role these structures play in influencing synaptic integration and neural function. Despite significant advances in this field, genetic pleiotropy remains a significant impediment to investigating such complex developmental processes. To circumvent this problem, we have applied class specific neuron transcriptional expression profiling coupled to an in vivo RNAi functional validation screen in order to dissect the molecular bases of Drosophila class IV dendritic arborization (da) neuron dendritogenesis. Microarray analyses reveal transcriptional regulation as one highly enriched biological and functional category with 420 transcription factors significantly expressed in class IV neurons. Among these, we identify roles for 268 genes in mediating a broad spectrum of functions including dendritic field coverage, branching, routing, and tiling. Collectively, our analyses provide a more comprehensive framework of the role complex transcriptional networks play in directing distinct aspects of class specific dendrite morphogenesis. Gene expression profiling of class IV da neurons performed at the third instar larval stage of development from two independent cell isolations from 40-50 age-matched third instar larvae expressing mCD8::GFP under the control of the GAL4ppk.1.9 driver