Odd-skipped controls neurite morphology and affect cell survival in Drosophila Melanogaster CNS

The transcription factor Odd-skipped has been implicated in many developmental processes in Drosophila melanogaster. Odd-skipped is expressed in a small cluster of neurons (Slater, Levy et al.) in the developing and adult CNS but its role in neurogenesis has so far not been addressed. Here we show that Odd-skipped plays a pivotal role in neurite growth and arborization during development. Loss-of-Odd-skipped function prevents neurite outgrowth whereas over and miss-expression causes neurite growth and arborization defects. In addition, miss-expression of Odd-skipped can induce cell death in some neural sub types. The neurite growth and arborization defects associated with Odd-skipped over expression correlates with a reduction in the pre-synaptically targeted protein Bruchpilot in axonal arbours suggesting an overall decrease in Odd neural synapse formation. This is supported by behavioural data showing that larvae in which Odd-skipped is overexpressed behave similarly to larvae in which Odd neurons are silenced showing that increasing Odd-skipped protein levels affect neural function. Finally, we demonstrate that using RNAi against Odd-skipped does not knock down Odd-skipped protein but instead cause an increase in protein levels compared to control larvae. This data demonstrates that RNAi can cause up-regulation of protein levels highlighting the importance of verifying protein levels when using RNAi approaches for knock-down.