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Abstract

CO2 sensation represents an interesting example of nervous system and
behavioral evolutionary divergence. The underlying molecular
mechanisms, however, are not understood. Loss of microRNA-279 in
Drosophila melanogaster leads to the formation of a CO2 sensory system
partly similar to the one of mosquitoes. Here, we show that a novel
allele of the pleiotropic transcription factor Prospero resembles the
miR-279 phenotype. We use a combination of genetics and in vitro and in
vivo analysis to demonstrate that Pros participates in the regulation
of miR-279 expression, and that reexpression of miR-279 rescues the
pros CO2 neuron phenotype. We identify common target molecules of
miR-279 and Pros in bioinformatics analysis, and show that
overexpression of the transcription factors Nerfin-1 and Escargot (Esg)
is sufficient to induce formation of CO2 neurons on maxillary palps.
Our results suggest that Prospero restricts CO2 neuron formation
indirectly via miR-279 and directly by repressing the shared target
molecules, Nerfin-1 and Esg, during olfactory system development. Given
the important role of Pros in differentiation of the nervous system, we
anticipate that miR-mediated signal tuning represents a powerful method
for olfactory sensory system diversification during evolution.