A Targeted Gain-of-Function Screen Identifies Genes Affecting Salivary Gland Morphogenesis/Tubulogenesis in Drosophila

Abstract

During development individual cells in tissues undergo complex cell-shape changes to drive the morphogenetic movements required to form tissues. Cell shape is determined by the cytoskeleton and cell-shape changes critically depend on a tight spatial and temporal control of cytoskeletal behavior. We have used the formation of the salivary glands in the Drosophila embryo, a process of tubulogenesis, as an assay for identifying factors that impinge on cell shape and the cytoskeleton. To this end we have performed a gain-of-function screen in the salivary glands, using a collection of fly lines carrying EP-element insertions that allow the overexpression of downstream-located genes using the UAS-Gal4 system. We used a salivarygland-specific fork head-Gal4 line to restrict expression to the salivary glands, in combination with reporters of cell shape and the cytoskeleton. We identified a number of genes known to affect salivary gland formation, confirming the effectiveness of the screen. In addition, we found many genes not implicated previously in this process, some having known functions in other tissues. We report the initial characterization of a subset of genes, including chickadee, rhomboid1, egalitarian, bitesize, and capricious, through comparison of gain-and loss-of-function phenotypes.

The Garz Sec7 domain guanine nucleotide exchange factor for Arf regulates salivary gland development in Drosophila

“…Our findings in Garz-depleted animals are consistent with results from a targeted gain-of-function screen in which overexpression of Garz at early stages of gland development resulted in the formation of abnormal hooked salivary glands. 65 The observed disorganization of the Garz-depleted salivary glands correlates with disruption in the localization of Dlg and subcortical GFP-actin, suggesting disturbance in the establishment or maintenance of cell polarity. The Garz-depletion phenotype is similar to that caused by mutations in Nak, a kinase that regulates phosphorylation of AP complexes.…”

Rho GTPase controls Drosophila salivary gland lumen size through regulation of the actin cytoskeleton and Moesin

“…Loss of chic disrupts actindependent processes during Drosophila oogenesis and embryogenesis (Cooley et al, 1992;Verheyen and Cooley, 1994), and overexpression of chic in the salivary gland perturbs gland invagination and morphology (Maybeck and Roper, 2009). In chic 221 mutant embryos, gland lumens were widened and shortened, and gland cells failed to elongate their apical domains and rearrange, as was also observed in Rho1 1B mutant embryos (supplementary material Fig.…”

Genetic Regulation of Salivary Gland Development in <i>Drosophila melanogaster</i>

“…Further analysis of smaller deficiencies that delete genomic intervals contained within one of the 34 genomic intervals led to the identification of a novel role for β2t in salivary gland migration as described above. A recently reported gain-of-function screen for genes affecting salivary gland development utilized a salivary gland-specific GAL4 driver, fkh-GAL4, to drive expression of transposable element (EP element) lines [42]. In such an approach, binding of GAL4 to UAS sites within the EP element, in most cases, leads to overexpression of the downstream gene.…”