Notch-dependent Abl signaling regulates cell motility during ommatidial rotation in Drosophila

Abstract

A collective cell motility event that occurs during Drosophila eye development, ommatidial rotation (OR), serves as a paradigm for signaling pathway-regulated directed movement of cell clusters. OR is instructed by several signaling events, including the EGFR and Notch pathways, and planar cell polarity (PCP) signaling, all of which are associated with photoreceptor R3 and R4 specification and differentiation. Here, we show that Abl kinase negatively regulates ommatidial rotation through its activity in the R3/R4 pair. Interestingly in wild-type, Abl is localized to apical junctional regions in R4 but not in R3 during OR, and this apical enrichment requires Notch signaling. We further demonstrate that Abl and Notch genetically interact during OR, and Abl co-immunoprecipitates in complexes with Notch in the developing eye disc. Perturbations of Abl interfere with adherens junction dynamics of the ommatidial preclusters, which are critical for the OR process. Taken together, our data suggest a model in which Abl kinase acts directly downstream of the Notch receptor in R4 to fine-tune OR via its input into adherens junction complexes.