| Summary: | <p>Abstract</p> <p>Background</p> <p>The antenno-maxilary complex (AMC) forms the chemosensory system of the <it>Drosophila </it>larva and is involved in gustatory and olfactory perception. We have previously shown that a mutant allele of the homeodomain transcription factor Prospero (<it>prosVoila1</it>, <it>V1</it>), presents several developmental defects including abnormal growth and altered taste responses. In addition, many neural tracts connecting the AMC to the central nervous system (CNS) were affected. Our earlier reports on larval AMC did not argue in favour of a role of <it>pros </it>in cell fate decision, but strongly suggested that <it>pros </it>could be involved in the control of other aspect of neuronal development. In order to identify these functions, we used microarray analysis of larval AMC and CNS tissue isolated from the wild type, and three other previously characterised <it>prospero </it>alleles, including the <it>V1 </it>mutant, considered as a null allele for the AMC.</p> <p>Results</p> <p>A total of 17 samples were first analysed with hierarchical clustering. To determine those genes affected by loss of <it>pros </it>function, we calculated a discriminating score reflecting the differential expression between <it>V1 </it>mutant and other <it>pros </it>alleles. We identified a total of 64 genes in the AMC. Additional manual annotation using all the computed information on the attributed role of these genes in the <it>Drosophila </it>larvae nervous system, enabled us to identify one functional category of potential Prospero target genes known to be involved in neurite outgrowth, synaptic transmission and more specifically in neuronal connectivity remodelling. The second category of genes found to be differentially expressed between the null mutant AMC and the other alleles concerned the development of the sensory organs and more particularly the larval olfactory system. Surprisingly, a third category emerged from our analyses and suggests an association of <it>pros </it>with the genes that regulate autophagy, growth and insulin pathways. Interestingly, EGFR and Notch pathways were represented in all of these three functional categories. We now propose that Pros could perform all of these different functions through the modulation of these two antagonistic and synergic pathways.</p> <p>Conclusions</p> <p>The current data contribute to the clarification of the <it>prospero </it>function in the larval AMC and show that <it>pros </it>regulates different function in larvae as compared to those controlled by this gene in embryos. In the future, the possible mechanism by which Pros could achieve its function in the AMC will be explored in detail.</p>
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