Affiliation: Graduate School of Science, Chiba University, Japan
Keywords: g. wing disc; g. wing disc
Conserved and ancient genes often play essential roles in various biological processes, whereas young genes, which exist in only one or a few species, had been considered to perform relatively minor functions. Recent studies in Drosophila have demonstrated that young genes play important roles in morphogenesis and behavioral decision. However, little is known about the involvement of young genes in the development of the Drosophila wing. Here we show two young genes four-jointed localization factor (flf) 1 and flf2 function redundantly to regulate Wingless (Wg) signaling in the Drosophila wing development.
In a previous study, we identified flf1 as a modulator of the cellular localization of the Golgi kinase Four-jointed. Moreover, we identified flf2, a paralogous gene of flf1, by using nucleotide BLAST against the Drosophila reference genome. flf1 and flf2 are tandemly arrayed genes, and the amino acid sequences of their translation products are highly similar. For further analysis of functions of flf1 and flf2, we produced mutations of these two genes by using CRISPR/Cas9 system. Single mutant flies that lack flf1 or flf2 developed and reproduced without an obvious phenotype. By contrast, the number of chemosensory bristles was decreased in the adult wings of flf1flf2 double mutant. An abnormal number of chemosensory bristles in the adult wings is found in wg mutants. Therefore, we decided to investigate relationship between flf(s) and Wg signaling. Wg puncta diffusing away from the dorso-ventral boundary cells was decreased in the wing imaginal discs of flf1flf2 double mutant. This result indicates that flf1 and flf2 are required for normal expression pattern of Wg in the wing imaginal discs. To test whether Flf(s) affect Wg diffusion in a dose dependence manner, we overexpressed flf1 or flf2 in the wing imaginal discs. Overexpression of Flf1 or Flf2 enhanced Wg diffusion in the wing imaginal discs. Our results suggest requirement of flf1 and flf2 for proper expression pattern and function of Wg in the Drosophila wing development.