Imaging Cytonemes in Drosophila Embryos

Abstract

Conserved morphogenetic signaling proteins disperse across tissues to generate signal and signaling gradients, which in turn are considered to assign positional coordinates to the recipient cells. Recent imaging studies in Drosophila model have provided evidence for a “direct-delivery” mechanism of signal dispersion that is mediated by specialized actin-rich signaling filopodia, named cytonemes. Cytonemes establish contact between the signal-producing and target cells to directly exchange and transport the morphogenetic proteins. Although an increasing amount of evidence supports the critical role of these specialized signaling structures, imaging these highly dynamic 200 nm-thin structures in the complex three-dimensional contour of living tissues is challenging. Here, we describe the imaging methods that we optimized for studying cytonemes in Drosophila embryos.

Cytonemes, Their Formation, Regulation, and Roles in Signaling and Communication in Tumorigenesis

“…Cytoneme-mediated delivery of signaling ligands has been shown for Dpp in the Drosophila wing disc, Wnt in zebrafish [40,65], Hh in Drosophila , and Shh in chick limb bud [23,25,49,55,59]. Conversely, cytonemes emanating from signal-receiving cells have been shown to participate in the distribution of the Drosophila FGF receptor homolog Breathless (Btl) in the developing ASP [66].…”