Imaging Cytonemes in Drosophila Embryos
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.
Key wordsCytonemes Cell–cell signaling Morphogen Drosophila Embryo Filopodia Trachea Engrailed Breathless
We thank Dr. T.B. Kornberg and the Bloomington Stock Center for reagents, colleagues and lab members, especially Alex Sohr for reading the manuscript and valuable suggestions, UMD Imaging core facility, and Dr. A.E. Beaven for assistance in the imaging core. Funding from NIH: R00HL114867 and R35GM124878 to S.R.
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