Chapter 281 - Drosophila Nuclear Receptors

Abstract

The completion of the Drosophila genome sequence in early 2000 revealed 21 nuclear receptor (NR) genes, about half of the 49 NR genes identified to date in the human genome. In striking contrast, ∼270 NR genes have been described in Caenorhabditis elegans. It seems likely that the ∼255 nematode-specific NRs reflect an adaptation unique to the nematode group. The 21 Drosophila NRs represent all major subfamilies described previously, and 16 receptors appear to have orthologs in either vertebrates or nematodes, or both. The other two receptors, DHR39 and DHR83, are closely related to FTZ-Fl and dFAX-1, respectively, and probably represent—in evolutionary terms—relatively recent splits within the arthropod lineage. In general, it appears that most Drosophila NRs are more similar to their human counterparts than to the corresponding C. elegans homolog. The fruit fly, Drosophila melanogaster, provides an ideal system to analyze NR function in the context of a developing organism, with a wide range of genetic tools that allow the dissection of regulatory pathways and in-depth characterization of gene function.