Gain‐of‐function screen identifies a role of the Src64 oncogene in Drosophila mushroom body development

Abstract

Mushroom bodies (MB) are substructures in the Drosophila brain that are essential for memory. At present, MB anatomy is rather well described when compared to other brain areas, and elucidation of the genetic control of the development and projection patterns of MB neurons will be important to the understanding of their functions. We have performed a gain-of-function screen in order to identify genes that are involved in MB development. We drove expression of genes in MB neurons by crossing 2407 GAL4-driven UY element lines to lines containing an MB GAL4 source and UAS-GFP elements, and looked for defects in the MB structure. We have molecularly identified the genomic regions adjacent to the 26 positive UY insertions and found 18 potential genes that exhibit adult MB gain-of-function phenotypes. The proteins encoded by these candidate genes include, as well as genes with yet unknown function, transcription factors (e.g., tramtrack), nanos RNA-binding protein, microtubule-severing protein, vesicle trafficking proteins, axon guidance receptor, and the Src64 cytoplasmic protein tyrosine kinase. These genes are involved in key features of neuron cell biology. In three cases, tramtrack, nanos, and Src64, we show that the open reading frame located directly downstream of the UY P element is indeed the expressed target gene. Loss-of-function mutations of both ttk and Src64 lead to MB phenotypes proving that these genes are involved in the genetic control of MB development. Moreover, Src64 is shown here to act in a cell-autonomous fashion and is likely to interact with the previously-identified linotte/derailed receptor tyrosine kinase in MB development.

Genetic Annotation of Gain-Of-Function Screens Using RNA Interference and in Situ Hybridization of Candidate Genes in the Drosophila Wing

“…The use of overexpression to identify candidate genes affecting a particular process was busted when the UAS sequences were incorporated into the P-element, allowing the screen of large collections of P-UAS elements (Rorth et al 1998). These screens have been applied to a variety of processes, such as imaginal development (Rorth 1996;Tseng and Hariharan 2002;Cruz et al 2009), vein patterning (Molnar et al 2006b), sensory organ formation (AbdelilahSeyfried et al 2001), motor axon guidance (Kraut et al 2001), and many others (Huang and Rubin 2000;Pena-Rangel et al 2002;McGovern et al 2003;Nicolai et al 2003;Hall et al 2004;Schulz et al 2004). In all these cases the screens were successful in identifying candidate genes affecting the process of interest when overexpressed, with a fraction of positive insertions of between 1 and 10% depending on the P-UAS element used and the particular experimental system.…”

Roles of Type I Myosins in Drosophila Handedness

“…spastin and katanin-60 encode ATPases that negatively regulate microtubule stability. 20,21 Overexpression of spastin or katanin-60 in the hindgut epithelium did not affect the laterality of this organ (Table 1). These results suggest that the embryonic hindgut develops its LR asymmetric morphology in an actin-dependent but microtubule-independent manner.…”

ftz-f1 and Hr39 opposing roles on EcR expression during Drosophila mushroom body neuron remodeling

“…Larval, pupal and adult brains were dissected and treated as previously described 38 . For the clonal analysis study (MARCM) the clones were induced in first instar by applying a 1 h heat-shock at 37 °C as previously described 12,24 .…”